Display device with variable color background for evaluating displayed value

Abstract

A light emitting diode display device includes a variable color display area, for exhibiting a selective display unit, substantially surrounded by a variable color background area. The light emitting diodes in the display area are commonly coupled to a plurality of display buses, in accordance with their display colors. Similarly, the light emitting diodes in the background area are commonly coupled to a plurality of background buses, in accordance with their background colors. A display color control is provided for selectively activating the display buses, for illuminating a desired display unit in a selective color. A background color control is further provided for activating the background buses, for illuminating the background area in a uniform color different from the color of the display area.

Description

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] This invention relates to a variable color display device having display area and background area.

[0005] 2. Description of the Prior Art

[0006] A driving circuit for light emitting diodes, described in U.S. Pat. No. 3,740,570, issued on Jun. 19, 1973 to George R. Kaelin et al., utilizes special light emitting diodes that emit light of different colors in response to different currents.

[0007] An electronic display having segments wherein each segment is capable of selectively illuminating two colors is disclosed in U.S. Pat. No. 4,488,149 issued on Dec. 11, 1984 to William A. Givens, Jr. Two AND gates are provided for biasing, in each display segment, either a first light emitting diode, for emitting a first color, or a second light emitting diode, for emitting a second color. It is not contemplated to illuminate both light emitting diodes in each segment simultaneously for blending the colors.

[0008] A multi-colour LED display for seven segment figures is disclosed in German Patent No. 3,009,416 issued on Sep. 17, 1981 to Klaus Gillessen. The LED circuit consists of seven group of diodes, each group made up of two diodes, one red and one green. The cathodes of all red diodes are terminated in a common connection, and the green ones likewise, the anodes of each pair of diodes being common for that pair. Two transistors connected in cascade are utilized for activating either all green LEDs, or all red LEDs, but not both simultaneously. When a low level signal is applied to the base of the first transistor, the first transistor is blocked, and the second transistor is turned ON to illuminate the second set of the diodes. When a high level signal is applied to the input of the first transistor, the first transistor is turned ON, while the second transistor is blocked, whereby the first set of the diodes is illuminated. Since the first transistor cannot be simultaneously turned ON and OFF, it would be impossible to illuminate the two sets of the diodes simultaneously. In another embodiment is shown a multi-colour LED display utilizing three sets of LEDs: red, green, and blue, which are respectively commonly connected and may be activated by manual switches. It is not contemplated that the three sets of LEDs be activated in selective combinations to blend the colors.

[0009] A digital electrooptical display with anti-parallel light emitting diodes is disclosed in East German Patent No. 220,844 issued on Apr. 10, 1985 to Thomas Hoffman et al. Two light emitting diodes for emitting light of different colors are connected in each segment back-to-back. Since the light emitting diodes are connected to conduct currents in opposite directions, it would be impossible to illuminate them simultaneously, because the opposite currents would cancel.

[0010] A method and apparatus for independent color control of alphanumeric display and background therefor are disclosed in U.S. Pat. No. 3,911,418, issued on Oct. 7, 1975 to Minoru Takeda. In order to exhibit a character in a desired color, the code of the character and its color code are entered from a keyboard. A color code for the background area is then entered from the keyboard, independently of the color code for the displayed character. All entered codes are then encoded into a composite train of pulses, which are then separated, decoded, and used for exhibiting on a cathode ray tube device the desired character in the desired color, and for controlling color of its background.

[0011] The prior art does not contemplate a variable color light emitting diode display device having display area and background area, in which the display light emitting diodes are coupled to, and controlled by, display buses, and the background light emitting diodes are coupled to, and controlled by, background buses.

SUMMARY OF THE INVENTION

[0012] Accordingly, It is the principal object of this invention to provide an improved display device having a variable color display area and a variable color background area.

[0013] It is another object of the invention to provide a variable color display device including three colored light emitting diodes.

[0014] It is still another object of the invention to provide a variable color display device, in which the light emitting diodes for emitting light of different colors are respectively coupled to common electric paths called buses.

[0015] It is still another object of the invention to provide a variable color display device, in which the light emitting diodes are coupled to the buses in accordance with their physical location.

[0016] It is still another object of the invention to provide a variable color display device, in which the display buses are selectively controlled by display color control signals.

[0017] It is still another object of the invention to provide a variable color display device, in which the background buses are selectively controlled by background color control signals.

[0018] Other objects of the invention will be obvious from the appended drawings and their description.

[0019] In summary, a variable color display device of the invention, having a display area substantially surrounded by a background area, includes a plurality of display and background light emitting diodes for emitting, when forwardly biased, light signals of respective colors. All display light emitting diodes are coupled to a display bus system. Similarly, all background light emitting diodes are coupled to a background bus system. A display color control is provided for selectively applying display color control signals to the display bus system, for illuminating a selected display unit on the display area in a first selective color. A background color control is provided for selectively applying background color control signals to the background bus system, for illuminating the background area in a second selective colors. The invention resides in simultaneously providing the color controls for the display color and the background color of the display device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the drawings in which are shown the preferred embodiments of the invention,

[0021] FIG. 1 is a block diagram of a digital voltmeter with a variable color display.

[0022] FIG. 2 is a block diagram of a variable color digital voltmeter with an analog comparator.

[0023] FIG. 3 is a block diagram of a variable color digital voltmeter with a digital comparator.

[0024] FIG. 4 is a simplified schematic diagram of a digital voltmeter of the invention.

[0025] FIG. 5 is an exemplary detail of the display on which measured result is displayed in yellow color on green background.

[0026] FIG. 6 is a similar detail of the display on which measured result is displayed in yellow color on blue background.

[0027] FIG. 7 is a similar detail of the display on which measured result is displayed in yellow color on red background.

[0028] FIG. 8 is a simplified schematic diagram of one element of a variable color display device.

[0029] FIG. 9 is a cross-sectional view, taken along the line A-A in FIG. 6, revealing internal structure of a portion of a variable color display device.

[0030] FIG. 10 is a schematic diagram of an analog comparator for developing color control signals.

[0031] FIG. 11 is a schematic diagram of a digital comparator for developing color control signals.

[0032] FIG. 12 is a detail of 13-bit digital comparator in FIG. 11.

[0033] Throughout the drawings, like character indicate like parts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Referring now, more particularly, to the drawings, in FIG. 1 is shown a block diagram of a digital voltmeter utilizing a variable color display surrounded by a variable color background area. The digital voltmeter includes an A/D (analog to digital) converter 51, for converting an analog signal Vin applied to its input to digital data, and a display decoder 23 for causing the digital data to be displayed in a character format on a variable color display 11, in a manner well known to those skilled in the art. As will be more specifically pointed out subsequently, the display 11 includes variable color display areas arranged in a pattern and integral variable color background area. The invention resides in the addition of a segment color control 21 for illuminating the display areas in a suitable color and a background color control 22 for illuminating the background area in a color related to the measured value. The digital voltmeter of this invention can thus simultaneously indicate the measured value, in a character format, and its significance, in a color of the display background. By way of an example, measured value that is considered to be normal may be indicated on green background, measured value that is slightly abnormal may be indicated on blue background, and measured value that is critical may be indicated on red background.

[0035] In FIG. 2 is shown a block diagram of a like digital voltmeter characterized by an analog comparator 81. The input of analog comparator 81 is coupled to the input of A/D converter 51 for comparing the input signal with predetermined limits and for developing comparison signals accordingly. The background color control 22 illuminates the background area of the display in accordance with the comparison signals.

[0036] In FIG. 3 is shown a block diagram of a like digital voltmeter characterized by a digital comparator 84. The input of digital comparator 84 is coupled to the output of A/D converter 51 for comparing the output digital data with predetermined limits and for developing comparison signals accordingly. The background color control 22 illuminates the background area of the display in accordance with the comparison signals.

[0037] In FIG. 4 is shown a schematic diagram of a digital voltmeter of this invention which includes a DVM (digital voltmeter) chip 53 for measuring input signal Vin applied, via a resistor 90a and decoupling capacitor 93a, to its HI (high) and LO (low) inputs, and for developing segment drive signals a, b, c, d, e, f, g, and DP (decimal point) for a 3 ½ digit variable color display 41 on which measured values of the input signal may be indicated in a character format. Resistor 90b and capacitor 93b, coupled to input OSCILLATORS, are provided for selecting a suitable frequency of internal oscillators. An auto zero capacitor 93c tends to decrease noise. Integrating capacitor 93d and buffer resistor 90c provide desired voltage swing and linearity.

[0038] The first display element of the display 41 consists of a figure ‘1’ and a minus sign. The second, third, and fourth display elements consist of seven segments arranged in a well known 7-segment font on which selected characters may be exhibited in variable color. In the second element, the segments are designated as 31a, 31b, 31c, 31d, 31e, 31f, and 31g. Each display element has three color control inputs R (red), G (green), and B (blue) designated DISPL. Each display element is surrounded by a variable color background area, as will be more clearly pointed out subsequently. The background area of each display element also has three color control inputs R, G, and B designated as BACK. It is obvious from the illustration that the color control inputs of the display elements and background areas are respectively interconnected to form DISPLAY BUSES R, G, and B, for controlling color of all display elements uniformly, and BACKGROUND BUSES R, G, and B, for controlling color of the entire background 32 area uniformly.

[0039] FIGS. 5 to 7 are examples of displayed measured values which consider exemplary low limit −1.5 and high limit 1.5 (in Volts or in any other suitable units). The invention resides in controlling the color of background area 32 to indicate whether the measured value lies within the bounds of the low and high limits, below the low limit, or above the high limit. FIG. 5 shows a display on which a measured value 1.234 is displayed on green background, to indicate that it lies within the bounds of the low and high limits. FIG. 6 shows a display on which a measured value −1.789 is displayed on blue background, to indicate that it lies below the low limit. FIG. 7 shows a display on which a measured value 1.956 is displayed on red background, to indicate that it lies above the high limit. To render the illustration less complex, all measured values are displayed in yellow color. It will be appreciated that the color of the display may be also varied, to enhance the presentation, as described in more detail in the above identified copending application.

[0040] It is readily apparent that the method of displaying measured values shown in FIGS. 5 to 7 is extremely advantageous. Being completely surrounded by the background area 32, all display elements of the display 41 are distinctly associated therewith. It is perfectly clear that the color of the background area relates only to the values exhibited on the display elements within its boundaries, and not to values exhibited on display elements which may be located outside the boundaries.

[0041] Proceeding now to the detailed description, in FIG. 8 is shown a simplified schematic diagram of a one-character 7-segment variable color display element with variable color background. Each display segment of the display element includes a triad of closely adjacent LEDs: a red LED 1, green LED 2, and blue LED 3 which are adapted for producing a composite light signal of a variable color. To facilitate the illustration, the LEDs are designated by segment letters, e. g., red LED in the segment b is shown at 1b, green LED in the segment d is shown at 2d, and blue LED in the segment f is shown at 3f. The background area is comprised of background regions adjacent the display segments. Each background region includes a triad of closely adjacent LEDs: a red LED 4, green LED 5, and blue LED 6 which are adapted for producing a composite light signal of a variable color. As much as possible, the LEDs in the background regions are designated by letters of adjacent display segments.

[0042] The cathodes of all red, green, and blue display LED triads are interconnected in each display segment and electrically connected to respective inputs a, b, c, d, e, f, g, and DP (decimal point) which may be coupled to the outputs of DVM chip 53 viewed in FIG. 4. The anodes of all display red LEDs 1a, 1b, 1c, 1d, 1e, 1f, 1g, and 1i are commonly coupled to an electric path referred to as a display red bus 12. The anodes of all display green LEDs 2a, 2b, 2c, 2d, 2e, 2f, 2g, and 2i are commonly coupled to a like electric path referred to as a display green bus 13. The anodes of all display blue LEDs 3a, 3b, 3c, 3d, 3e, 3f, 3g, and 3i are commonly coupled to a like electric path referred to as a display blue bus 14.

[0043] In a similar fashion, the anodes of all background red LEDs 4a, 4b, 4c, 4d, 4e, 4f, 4g, and 4h are commonly coupled to an electric path referred to as a background red bus 16. The anodes of all background green LEDs 5a, 5b, 5c, 5d, 5e, 5f, 5g and 5h are commonly coupled to a like electric path referred to as a background green bus 17. The anodes of all background blue LEDs 6a, 6b, 6c, 6d, 6e, 6f, 6g, and 6h are commonly coupled to a like electric path referred to as a background blue bus 18. The cathodes of all red, green, and blue LED triads in each background region are grounded.

[0044] The display red bus 12 is connected to the output of a non-inverting buffer 25a capable of sourcing sufficient current to illuminate all display red LEDs. The display green bus 13 is connected to the output of a like buffer 25b. The display blue bus 14 is connected to the output of a like buffer 25c. The background red bus 16 is connected to the output of a like buffer 25d. The background green bus 17 is connected to the output of a like buffer 25e. The background blue bus 18 is connected to the output of a like buffer 25f. It would be obvious to those skilled in the art that current limiting resistors may be connected in series with all LEDs in the circuit to constrain current flow.

[0045] The operation of the display element shown in FIG. 4 will be now explained on example of illuminating digit ‘1’ in yellow color. To exhibit decimal number ‘1’, low voltage levels are applied to the inputs b and c, to illuminate equally designated segments, and high voltage levels are applied to all remaining inputs, to extinguish all remaining segments.

[0046] To illuminate the display element in yellow color, the color control inputs R and G of the display buses are raised to a high logic level, while color control input B is maintained at a low logic level. As a result, the outputs of buffers 25a and 25b rise to a high logic level. The current flows from the output of buffer 25a, via display red bus 12 and red LED 1b, to the input b, and, via red LED 1c, to the input c. The current also flows from the output of buffer 25b, via display green bus 13 and green LED 2b, to the input b, and, via green LED 2c, to the input c. As a result of blending light signals of red and green colors in the segments b and c, the segments illuminate in substantially yellow color, creating a visual impression of a character ‘1’.

[0047] To illuminate the background area in green color, the color control input G of the background buses is raised to a high logic level, while the remaining color control inputs R and B are low. As a result, the output of buffer 25e rises to a high logic level. The current flows therefrom, via background green bus 17 and green LEDs 5a, 5b, 5c, 5d, 5e, 5f, 5g, and 5h in all background regions, to ground. The entire background area illuminates in green color.

[0048] To illuminate the background area in blue color, the color control input B of the background buses is raised to a high logic level, while the remaining color control inputs R and G are low. As a result, the output of buffer 25f rises to a high logic level. The current flows therefrom, via background blue bus 18 and blue LEDs 6a, 6b, 6c, 6d, 6e, 6f, 6g, and 6h in all background regions, to ground. The entire background area illuminates in blue color.

[0049] To illuminate the background area in red color, the color control input R of the background buses is raised to a high logic level, while the remaining color control inputs G and B are low. As a result, the output of buffer 25d rises to a high logic level. The current flows therefrom, via background red bus 16 and red LEDs 4a, 4b, 4c, 4d, 4e, 4f, 4g, and 4h in all background regions, to ground. The entire background area illuminates in red color.

[0050] An important consideration has been given to physical arrangement of the LEDs in the display areas and background regions, as illustrated in FIG. 9. Display red LED 1f, green LED 2f, and blue LED 3f are disposed on a support 10 in a display light blending cavity 8f and completely surrounded by transparent light scattering material 34. When forwardly biased, the LEDs 1f, 2f, and 3f emit light signals of red, green, and blue colors, respectively, which are blended by passing through light scattering material 34, acting to disperse the light signals, to form a composite light signal that emerges at the upper surface 35f. The color of the composite light signal may be controlled by varying the portions of red, green, and blue light signals. Display red LED 1b, green LED 2b, and blue LED 3b are similarly disposed in a display light blending cavity 8b and may be similarly activated.

[0051] In a similar fashion, background red LED 4g, green LED 5g, and blue LED 6g are disposed on the support 10 in a background light blending cavity 9g and surrounded by transparent light scattering material 34. When forwardly biased, the LEDs 4g, 5g, and 6g emit light signals of red, green, and blue colors, respectively, which are blended by passing through the light scattering material 34 to form a composite light signal of a composite color that emerges at the upper surface 36g.

[0052] The display light blending cavities are optically separated from adjacent background light blending cavities by opaque walls. The display light blending cavity 8f is defined by walls 7a and 7b. The walls have generally smooth inclined surfaces defining an obtuse angle with the support 10. The walls 7b and 7c similarly define a background light blending cavity 9g therebetween. In a similar fashion, the display light blending cavity 8b is defined by the walls 7c and 7d. The width of the top surfaces of the opaque walls is uniform and distinctly less than the width of the display areas or background regions so as to minimize the boundaries therebetween. The top surfaces of the opaque walls and top surfaces of the display areas and background regions are in the same plane to allow wide angle observation of the display device. Although the walls and light blending cavities are shown to be of certain shapes and dimensions, it is envisioned that they may be modified and rearranged.

[0053] In FIG. 10, the input signal Vin is applied to the interconnected inputs of two analog comparators 82a, 82b in a classic ‘window’ comparator configuration. When the input voltage is lower than the low voltage limit Vlo, set by a potentiometer 92a, the output of comparator 82a drops to a low logic level, thereby forcing the output of an inverter 65a to rise to a high logic level to develop active color control signal B.

[0054] When the input voltage is higher than the high voltage limit Vhi, set by a potentiometer 92b, the output of comparator 82b drops to a low logic level, thereby forcing the output of an inverter 65b to rise to a high logic level to develop active color control signal R.

[0055] When the input voltage is between the low voltage limit Vlo and high voltage limit Vhi, the outputs of comparators 82a, 82b rise to a high logic level (pull-up resistors 91a, 91b ensure correct high and low levels), thereby causing the output of AND gate 66 to rise to a high logic level to develop active color control signal G. The outputs B, G, and R may be respectively coupled to like inputs of the background buses in FIG. 4 to cause the background area 32 to illuminate in one of three colors in accordance with the range in which the measured voltage lies.

[0056] In FIG. 11 is shown a schematic diagram of a digital voltmeter with a comparator for developing color control signals. A DVM chip 54 measures input signal Vin applied via a resistor 90f to its input IN and develops at its outputs A, B, C, D of Units, Tens, Hundreds, and Thousand digital data corresponding to the value of measured input signal. The input INIT CONV (initiate conversion) is tied to a high logic level for causing the DVM chip to measure continuously. The output digital data are simultaneously applied to the inputs A0 to A12 of a 13-bit digital comparator 85a and to the inputs A0 to A12 of a like comparator 85b. Two 8-bit latches 63a, having its outputs Q0 to Q7 respectively coupled to the inputs B0 to B7 of comparator 85a, and 63b, having its outputs Q0 to Q4 respectively coupled to the inputs B8 to B12 of comparator 85a, are provided for storing a digital representation of a low limit. Two like latches 63c, having its outputs Q0 to Q7 respectively coupled to the inputs B0 to B7 of comparator 85b, and 63d, having its outputs Q0 to Q4 respectively coupled to the inputs B8 to B12 of comparator 85b, are provided for storing a digital representation of a high limit. The comparator 85a effects a comparison of the output digital data with the low limit and develops comparison signals accordingly. The comparator 85b effects a comparison of the output digital data with the high limit and develops comparison signals accordingly. It would be obvious that data in the latches may be readily changed by applying new data to the inputs D0 to D7 and clocking same into the latches (not shown).

[0057] When the output digital data of DVM chip 54 are less than the low limit, the output ‘<’ of comparator 85a rises to a high logic level to generate an active color control signal B. When the digital data are greater than the high limit, the output ‘>’ of comparator 85b rises to a high logic level to generate an active color control signal R. When the digital data are within the bounds of the low and high limits, one of the outputs ‘=’ and ‘>’ of comparator 85a, which are gated by an OR gate 60a, and one of the outputs ‘<’ and ‘=’ of comparator 85b, which are gated by an OR gate 60b, rise to a high logic level to force both inputs of an AND gate 66b to rise to a high logic level. As a consequence, the output of OR gate 66b rises to a high logic level to generate active color control signal G. The comparison outputs B, G, and R may be respectively coupled to like inputs of the background buses in FIG. 4 for causing the background area 32 of the display 41 to illuminate either in blue color when the measured value is less than the low limit, in red color when the measured value is greater than the high limit, or in green color when the measured value is within the bounds of the low and high limits. It would be obvious that the color sequences could be readily changed by differently interconnecting the comparison outputs with the background color control inputs.

[0058] FIG. 12 is a detail of one of 13-bit digital comparators 85a, 85b in FIG. 11. It will be appreciated that both digital comparators 85a, 85b may be substantially same. The comparison inputs ‘<’, ‘=’, and ‘>’ of four 4-bit digital comparators 86a, 86b, 86c, and 86d are respectively coupled to like preceding outputs, in a manner well understood by those skilled in the art, to extend the comparison range to 13 bits.

[0059] The invention may be now briefly summarized. A display device having a variable color display area and a variable color background area was disclosed. The display area includes a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units. Each display segment includes a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors. The background area, adjacent to the display area, also includes a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors. A bus system is provided, to which the light emitting diodes are coupled in accordance with their location, either in the display segments or in the background area, and in accordance with their colors. A color control is provided for activating the bus system for illuminating a selected display unit, on certain of the display segments, in a first selective color, and for illuminating the background area in a second selective color.

[0060] The term “variable color background area” should be interpreted broadly as any background area integral with, adjacent to, or associated with, the display device and capable of being illuminated in a selective color.

[0061] It would be obvious that persons skilled in the art may resort to modifications in the construction of the preferred embodiments shown herein, without departing from the scope, as defined in the appended claims, and the spirit of the invention. It is contemplated that the principles of the invention may be also applied to numerous diverse types of display devices, such as liquid crystal devices, plasma devices, luminescent devices, cathode ray tube devices, and the like.

CORRELATION TABLE

[0062] This is a correlation table of reference characters used in the drawings herein, their descriptions, and examples of commercially available parts.

#	DESCRIPTION	EXAMPLE
1	display red LED
2	display green LED
3	display blue LED
4	background red LED
5	background green LED
6	background blue LED
7	opaque wall
8	display light blending cavity
9	background light blending cavity
10	support
11	variable color display
12	display red bus
13	display green bus
14	display blue bus
16	background red bus
17	background green bus
18	background blue bus
21	segment color control
22	background color control
23	display decoder
25	non-inverting buffer	74LS244
31	display segment
32	background area
34	light scattering material
35	top surface of display area
36	top surface of background area
41	3 1/2 digit variable color display
51	A/D converter
53	Teledyne DVM chip	TSC7107
54	Teledyne DVM chip	TSC8750
60	2-input OR gate	74HC32
63	8-bit latch	74HC373
65	inverter	74HC04
66	2-input AND gate	74HC08
81	analog comparator
82	analog comparator chip	LM339
84	digital comparator
85	13-bit digital comparator
86	4-bit digital comparator	74HC85
90	resistor
91	resistor
92	potentiometer
93	capacitor

Claims

1. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors; a background area adjacent to said display area, said background area including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors; a bus system to which said light emitting diodes are coupled in accordance with the location of said light emitting diodes either in said display segments or in said background area, and in accordance with their colors, for being forwardly biased upon selective activation of said bus system; and means for selectively activating said bus system for illuminating a selected display unit, on certain of said display segments, in a first selective color, and for illuminating said background area in a second selective color.

2. The display device of claim 1 wherein said background area is illuminated in a uniform color.

3. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors; a background area adjacent to said display area, said background area including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors; a plurality of display buses to which said light emitting diodes in said display segments are commonly coupled in accordance with their colors, for being forwardly biased upon selective activation of said display buses; means for selectively activating said display buses for illuminating a selected display unit, on certain of said display segments, in a first selective color; a plurality of background buses to which said light emitting diodes in said background area are commonly coupled in accordance with their colors, for being forwardly biased upon selective activation of said background buses; and means for selectively activating said background buses for illuminating said background area in a second selective color.

4. The display device of claim 3 wherein the number of said display buses is the same as the number of said background buses.

5. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color; a background area adjacent to said display area, said background area including a plurality of light emitting diodes arranged in triads, each said triad including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color; a first display bus to which all said first light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon activation of said first display bus; a second display bus to which all said second light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon activation of said second display bus; a third display bus to which all said third light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon activation of said third display bus; means for selectively activating said first display bus, said second display bus, and said third display bus, for illuminating a selected display unit, on certain of said display segments, in a first selective color; a first background bus to which all said first light emitting diodes in said background area are commonly coupled, for being forwardly biased upon activation of said first background bus; a second background bus to which all said second light emitting diodes in said background area are commonly coupled, for being forwardly biased upon activation of said second background bus; a third background bus to which all said third light emitting diodes in said background area are commonly coupled, for being forwardly biased upon activation of said third background bus; and means for selectively activating said first background bus, said second background bus, and said third background bus, for illuminating said background area in a second selective color.

6. The display device of claim 5 wherein said first color in said display area is the same as said first color in said background area, said second color in said display area is the same as said second color in said background area, and said third color in said display area is the same as said third color in said background area.

7. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors, said background area having a substantially flat top surface aligned with said top surface of said display area; a plurality of display buses to which said light emitting diodes in said display segments are commonly coupled in accordance with their colors, for being forwardly biased upon selective activation of said display buses; a display color control for selectively activating said display buses for illuminating a selected display unit, on certain of said display segments, in a first selective color; a plurality of background buses to which said light emitting diodes in said background area are commonly coupled in accordance with their colors, for being forwardly biased upon selective activation of said background buses; and a background color control for selectively activating said background buses for illuminating said background area in a second selective color.

8. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of light emitting diodes arranged in triads, each said triad including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color, said background area having a substantially flat top surface aligned with said top surface of said display area; a first display bus to which all said first light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon activation of said first display bus; a second display bus to which all said second light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon activation of said second display bus; a third display bus to which all said third light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon activation of said third display bus; a display color control for selectively activating said first display bus, said second display bus, and said third display bus, for illuminating a selected display unit, on certain of said display segments, in a first selective color; a first background bus to which all said first light emitting diodes in said background area are commonly coupled, for being forwardly biased upon activation of said first background bus; a second background bus to which all said second light emitting diodes in said background area are commonly coupled, for being forwardly biased upon activation of said second background bus; a third background bus to which all said third light emitting diodes in said background area are commonly coupled, for being forwardly biased upon activation of said third background bus; and a background color control for selectively activating said first background bus, said second background bus, and said third background bus, for illuminating said background area in a second selective color.

9. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of display light emitting diodes for emitting, when forwardly biased, light signals of respective display colors; a background area adjacent to said display area, said background area including a plurality of background light emitting diodes for emitting, when forwardly biased, light signals of respective background colors; a bus system for distributing display color control signals to said display light emitting diodes, in accordance with said display colors, and for distributing background color control signals to said background light emitting diodes, in accordance with said background colors; and means for selectively activating said bus system for illuminating a selected display unit, on certain of said display segments, in a first selective color, and for illuminating said background area in a second selective color.

10. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of display light emitting diodes for emitting, when forwardly biased, light signals of respective display colors; a background area adjacent to said display area, said background area including a plurality of background light emitting diodes for emitting, when forwardly biased, light signals of respective background colors; a plurality of display buses, equal in number to the number of said display colors, for distributing display color control signals to said display light emitting diodes, in accordance with their colors, for forwardly biasing said display light emitting diodes; means for selectively applying said color control signals to said display buses, for illuminating a selected display unit, on certain of said display segments, in a first selective color; a plurality of background buses, equal in number to the number of said background colors, for distributing background color control signals to said background light emitting diodes, in accordance with their colors, for forwardly biasing said background light emitting diodes; means for selectively applying said background color control signals to said background buses, for illuminating said background area in a second selective color.

11. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color; a background area adjacent to said display area, said background area including a plurality of light emitting diodes arranged in triads, each said triad including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color; a first display bus for distributing a first display color control signal to said first light emitting diodes in said display segments, for forwardly biasing them when said first display color control signal is applied to said first display bus; a second display bus for distributing a second display color control signal to said second light emitting diodes in said display segments, for forwardly biasing them when said second display color control signal is applied to said second display bus; a third display bus for distributing a third display color control signal to said third light emitting diodes in said display segments, for forwardly biasing them when said third display color control signal is applied to said third display bus; means for selectively applying said first display color control signal to said first display bus, said second display color control signal to said second display bus, and said third display color control signal to said third display bus, for illuminating a selected display unit, on certain of said display segments, in a first selective color; a first background bus for distributing a first background color control signal to said first light emitting diodes in said background area, for forwardly biasing them when said first background color control signal is applied to said first background bus; a second background bus for distributing a second background color control signal to said second light emitting diodes in said background area, for forwardly biasing them when said second background color control signal is applied to said second background bus; a third background bus for distributing a third background color control signal to said third light emitting diodes in said background area, for forwardly biasing them when said third background color control signal is applied to said third background bus; means for selectively applying said first background color control signal to said first background bus, said second background color control signal to said second background bus, and said third background color control signal to said third background bus, for illuminating said background area in a second selective color.

12. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of display light emitting diodes for emitting, when forwardly biased, light signals of respective display colors, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of background light emitting diodes for emitting, when forwardly biased, light signals of respective background colors, said background area having a substantially flat top surface aligned with said top surface of said display area; a plurality of display buses, equal in number to the number of said display colors, for distributing display color control signals to said display light emitting diodes, in accordance with their colors, for forwardly biasing said display light emitting diodes; a display color control for selectively applying said display color control signals to said display buses for illuminating a selected display unit, on certain of said display segments, in a first selective color; a plurality of background buses, equal in number to the number of said background colors, for distributing background color control signals to said background light emitting diodes, in accordance with their colors, for forwardly biasing said background light emitting diodes; and a background color control for selectively applying said color control signals to said background buses for illuminating said background area in a second selective color.

13. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of light emitting diodes arranged in triads, each said triad including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color, said background area having a substantially flat top surface aligned with said top surface of said display area; a first display bus for distributing a first display color control signal to said first light emitting diodes in said display segments, for forwardly biasing them when said first display color control signal is applied to said first display bus; a second display bus for distributing a second display color control signal to said second light emitting diodes in said display segments, for forwardly biasing them when said second display color control signal is applied to said second display bus; a third display bus for distributing a third display color control signal to said third light emitting diodes in said display segments, for forwardly biasing them when said third display color control signal is applied to said third display bus; a display color control for selectively applying said first display color control signal to said first display bus, said second display color control signal to said second display bus, and said third display color control signal to said third display bus, for illuminating a selected display unit, on certain of said display segments, in a first selective color; a first background bus for distributing a first background color control signal to said first light emitting diodes in said background area, for forwardly biasing them when said first background color control signal is applied to said first background bus; a second background bus for distributing a second background color control signal to said second light emitting diodes in said background area, for forwardly biasing them when said second background color control signal is applied to said second background bus; a third background bus for distributing a third background color control signal to said second light emitting diodes in said background area, for forwardly biasing them when said third background color control signal is applied to said third background bus; a background color control for selectively applying said first background color control signal to said first background bus, said second background color control signal to said second background bus, and said third background color control signal to said third background bus, for illuminating said background area in a second selective color.

14. The display device of claim 13 wherein: said first display bus, said second display bus, and said third display bus include respective display color control inputs for receiving said first display color control signal, said second display color control signal, and said third display color control signal; said display color control applies said display color control signals to said display color control inputs, respectively; said first background bus, said second background bus, and said third background bus include respective background color control inputs for receiving said first background color control signal, said second background color control signal, and said third background color control signal; and said background color control applies said background color control signals to said background color control inputs, respectively.

15. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors; a background area adjacent to said display area, said background area including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors; a plurality of display buses to which said light emitting diodes in said display segments are commonly coupled in accordance with their colors, for being forwardly biased upon selective application of display color control signals to said display buses; means for selectively applying said display color control signals to said display buses for illuminating a selected display unit, on certain of said display segments, in a first selective color; a plurality of background buses to which said light emitting diodes in said background area are commonly coupled in accordance with their colors, for being forwardly biased upon selective application of background color control signals to said background buses; and means for selectively applying said background color control signals to said background buses for illuminating said background area in a second selective color.

16. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color; a background area adjacent to said display area, said background area including a plurality of light emitting diodes arranged in triads, each said triad including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color; a first display bus to which all said first light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon application of a first display color control signal to said first display bus; a second display bus to which all said second light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon application of a second display color control signal to said second display bus; a third display bus to which all said third light emitting diodes in said display segments are commonly coupled, for being forwardly biased upon application of a third display color control signal to said third display bus; means for selectively applying said first display color control signal to said first display bus, said second display color control signal to said second display bus, and said third display color control signal to said third display bus, for illuminating a selected display unit, on certain of said display segments, in a first selective color; a first background bus to which all said first light emitting diodes in said background area are commonly coupled, for being forwardly biased upon application of a first background color control signal to said first background bus; a second background bus to which all said second light emitting diodes in said background area are commonly coupled, for being forwardly biased upon application of a second background color control signal to said second background bus; a third background bus to which all said third light emitting diodes in said background area are commonly coupled, for being forwardly biased upon application of a third background color control signal to said third background bus; and means for selectively applying said first background color control signal to said first background bus, said second background color control signal to said second background bus, and said third background color control signal to said third background bus, for illuminating said background area in a second selective color.

17. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of light emitting diodes for emitting, when forwardly biased, light signals of respective colors, said background area having a substantially flat top surface aligned with said top surface of said display area; a plurality of display buses to which said light emitting diodes in said display segments are commonly coupled in accordance with their colors, each said display bus having a display color control input, responsive to a display color control signal, for forwardly biasing all said light emitting diodes coupled to said display bus when said display color control signal is active; a display color control for selectively applying active display color control signals to said display color control inputs for illuminating a selected display unit, on certain of said display segments, in a first selective color; a plurality of background buses to which said light emitting diodes in said background area are commonly coupled in accordance with their colors, each said background bus having a background color control input, responsive to a background color control signal, for forwardly biasing all said light emitting diodes coupled to said background bus when said background color control signal is active; a background color control for selectively applying active background color control signals to said background color control inputs for illuminating said background area in a uniform color different from said first selective color.

18. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of light emitting diodes arranged in triads, each said triad including a first light emitting diode for emitting, when forwardly biased, light signals of a first color, a second light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third light emitting diode for emitting, when forwardly biased, light signals of a third color, said background area having a substantially flat top surface aligned with said top surface of said display area; a first display bus to which all said first light emitting diodes in said display segments are commonly coupled, said first display bus having a first display color control input, responsive to a first display color control signal, for forwardly biasing all said first light emitting diodes when said first display color control signal is active; a second display bus to which all said second light emitting diodes in said display segments are commonly coupled, said second display bus having a second display color control input, responsive to a second display color control signal, for forwardly biasing all said second light emitting diodes when said second display color control signal is active; a third display bus to which all said third light emitting diodes in said display segments are commonly coupled, said third display bus having a third display color control input, responsive to a third display color control signal, for forwardly biasing all said third light emitting diodes when said third display color control signal is active; a display color control for applying a first display color control signal to said first display color control input, a second display color control signal to said second display color control input, and a third display color control signal to said third display color control input, one of said display color control signals being active, for illuminating a selected display unit, on certain of said display segments, in a first selective color; a first background bus to which all said first light emitting diodes in said background area are commonly coupled, said first background bus having a first background color control input, responsive to a first background color control signal, for forwardly biasing all said first light emitting diodes when said first background color control signal is active; a second background bus to which all said second light emitting diodes in said background area are commonly coupled, said second background bus having a second background color control input, responsive to a second background color control signal, for forwardly biasing all said second light emitting diodes when said second background color control signal is active; a third background bus to which all said third light emitting diodes in said background area are commonly coupled, said third background bus having a third background color control input, responsive to a third background color control signal, for forwardly biasing all said third light emitting diodes when said third background color control signal is active; a background color control for applying a first background color control signal to said first background color control input, a second background color control signal to said second background color control input, and a third background color control signal to said third background color control input, one of said background color control signals being active, for illuminating said background area in a uniform color different from said first selective color.

19. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a plurality of display light emitting diodes for emitting, when forwardly biased, light signals of respective colors, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of background light emitting diodes for emitting, when forwardly biased, light signals of respective colors, said background area having a substantially flat top surface aligned with said top surface of said display area; said colors of said display light emitting diodes being respectively the same as said colors of said background light emitting diodes; a plurality of display buses to which said light emitting diodes in said display segments are commonly coupled in accordance with their colors, each said display bus having a display color control input, responsive to a display color control signal, for forwardly biasing all said light emitting diodes coupled to said display bus when said display color control signal is active; a plurality of background buses to which said light emitting diodes in said background area are commonly coupled in accordance with their colors, each said background bus having a background color control input, responsive to a background color control signal, for forwardly biasing all said light emitting diodes coupled to said background bus when said background color control signal is active; wherein the number of said display buses is the same as the number of said background buses; a display color control for applying to said display color control inputs a selective combination of display color control signals, one of them being active, for causing the corresponding display light emitting diodes to illuminate; a background color control for applying to said background color control inputs a selective combination of background color control signals, one of them being active, for causing the corresponding background light emitting diodes to illuminate; wherein the active display color control signal is for a different color than the active background color control signal.

20. A display device comprising: a display area including a plurality of display segments arranged in a pattern for selectively exhibiting a plurality of display units, each said display segment including a first display light emitting diode for emitting, when forwardly biased, light signals of a first color, a second display light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third display light emitting diode for emitting, when forwardly biased, light signals of a third color, said display area having a substantially flat top surface; a background area substantially surrounding said display area, said background area including a plurality of light emitting diodes arranged in triads, each said triad including a first background light emitting diode for emitting, when forwardly biased, light signals of a first color, a second background light emitting diode for emitting, when forwardly biased, light signals of a second color, and a third background light emitting diode for emitting, when forwardly biased, light signals of a third color, said background area having a substantially flat top surface aligned with said top surface of said display area; a first display bus to which all said first display light emitting diodes are commonly coupled, said first display bus having a first display color control input, responsive to a first display color control signal, for forwardly biasing all said first display light emitting diodes when said first display color control signal is active; a second display bus to which all said second display light emitting diodes are commonly coupled, said second display bus having a second display color control input, responsive to a second display color control signal, for forwardly biasing all said second display light emitting diodes when said second display color control signal is active; a third display bus to which all said third display light emitting diodes are commonly coupled, said third display bus having a third display color control input, responsive to a third display color control signal, for forwardly biasing all said third display light emitting diodes when said third display color control signal is active; a display color control for applying to said first display color control input, to said second display color control input, and to said third display color control input a selective combination of display color control signals, wherein one of them is active, for causing the corresponding display light emitting diodes to illuminate; a first background bus to which all said first background light emitting diodes are commonly coupled, said first background bus having a first background color control input, responsive to a first background color control signal, for forwardly biasing all said first background light emitting diodes when said first background color control signal is active; a second background bus to which all said second background light emitting diodes are commonly coupled, said second background bus having a second background color control input, responsive to a second background color control signal, for forwardly biasing all said second background light emitting diodes when said second background color control signal is active; a third background bus to which all said third background light emitting diodes are commonly coupled, said third background bus having a third background color control input, responsive to a third background color control signal, for forwardly biasing all said third background light emitting diodes when said third background color control signal is active; a background color control for selectively applying to said first background color control input, to said second background color control input, and to said third background color control input a selective combination of background color control signals, wherein one of them is active, for causing the corresponding background light emitting diodes to illuminate; wherein the active display color control signal is for a different color than the active background color control signal.