3,909,788
`111]
`[I91 BEST AVMLABLE 001%?
`United States Patent
`Kaelin et al.1451*Sept. 30, 1975
`
`
`[54] DRIVING CIRCUITS FOR LIGHT
`EMITTING DIODES
`
`[58]
`
`Field of Search ................... 340/166 R, 166 EL
`
`1561
`
`3.740.570
`
`References Cited
`UNITED STATES PATENTS
`6/1973.
`Kaelin et al ................... 340/166 E1-
`
`Primary Liraminer—Donald J. Yusko
`
`ABSTRACT
`[57]
`LEDs are arranged in a matrix and driven by a pair of
`registers. A column register sequentially enables the
`columns of LEDs and a row register selectively oper-
`ates the LEDs of each column in accordance with a
`
`predetermined binary code. A color control and a
`brightness control circuit may be included in connec-
`tion with the row register to selectively control driving
`currents to the LEDs to control color hue. and to se-
`lectively control the duration of “on" time to control
`apparent brightness.
`
`10 Claims. 5 Drawing Figures
`
`[75]
`
`Inventors: George R. Kaelin, Woodland Hills;
`James A. Pellegrino. Thousand
`0““ [“01“ 0" Cum
`[731 Assignee: Litton Systems, Ine., Beverly Hills.
`Calif.
`The portion of the term of this
`patent subsequent to June 19, 1990.
`has been disclaimed.
`‘
`‘
`.
`Sept. 20’ 1973
`[22] Fllul'
`[21] Appl. No.: 399,232
`
`[ * I Notice:
`
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`US A
`‘1‘
`dta
`ppllcation
`" '
`R.“ dttd
`COHUIWUUU" 0f 5”- N0~ 367335“ JUNO 38- 1971
`abandoned. which is a continuation-in-part of Ser.
`No. 184.076. Sept. 37. 1971. Pat. No. 3.740.570.
`
`US. Cl ........ 340/166 R; 178/73 D: 340/324 R
`Int. CL“. H04Q 9/00: H04N 5/38: (108B 23/01)
`
`/7
`
`”Warm 74
`
`5703.465
`
`I
`
`I /77x I7
`
`
`
`HTC, Exhibit 1006
`
`HTC, Exhibit 1006
`
`

`

`US. Patent, ' Sept. 30,1975
`
`Sheet 1 of2
`
`3,909,788
`
`
`
`CLOCK
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`HTC, Exhibit 1006
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`HTC, Exhibit 1006
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`

`

`US. Patent
`
`Sept. 30,1975
`
`Sheet 2 of 2
`
`3,909,788
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`
`
`Bfi/GH T/VES 5
`C0NTROL
`
`FROM
`2 m
`REG/5 TEE
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`HTC, Exhibit 1006
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`HTC, Exhibit 1006
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`

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`l
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`3,909,788
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`2
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`DRIVING' CIRCUITS FOR LIGHT EMITTING
`DIODES
`
`This is a Continuation, of application Ser. No.
`267,238, filed June 28,
`l972 now abandoned; and
`which application isa continuation-in-part of our co-
`pending application Ser. No. '184,076 filed Sept. 27,
`1971, now U.S. Pat. No. 3,740,570 for “Driving Cir-
`cuits For Light Emitting Diodes” and assigned to the
`same assignee as the present invention.
`This invention relates to driving circuits for light
`emitting diodes, and particularly to circuits for driving
`light emitting diodes to achieve color display.
`Light emitting diodes (LEDs) are useful for alphanu-
`meric display purposes. LED arrays, when properly
`driven, can provide alpha-numeric read out of informa-
`tion from a computer. However, in prior LED arrays,
`the individual diodes were separately operated, so that
`driving circuits required for operating prior LED dis-
`plays required numerous connectionsto the display.
`The number of connections to prior LED display arrays
`rendered such arrays cumbersome in use and often ex—
`pensive to manufacture.
`It is an object of the present invention to provide
`driving circuits for LED display arrays whereby the
`LEDs may be selectively operated.
`It is another object of the present invention to pro-
`vide a LED driving and memory circuit which may be
`integrated with a LED matrix to form LED display ap-
`paratus requiring fewer interconnections than hereto-
`fore achieved.
`
`Certain LEDs exhibit different colors when subjected
`to driving currents of various amplitudes. Accordingly,
`it is yet another object of the present invention to pro-
`vide a driving circuit for a LED matrix for selectively
`varying the driving currents to the individual LEDs of
`the matrix to achieve a selectable color display.
`> Another object of the present invention is to provide
`intensity control apparatus in multicolor LED display
`apparatus.
`Another object of the present invention is to provide
`a LED driving circuit for selectively varying the pulse
`widths of driving current pulses to achieve selective in-
`tensity control of the LEDs.
`In accordance with the present invention, a plurality
`of LEDs are disposed in a two-dimensional matrix. The
`LEDs are arranged in rows and columns. A first shift
`register is provided for driving the LEDs along the rows
`and a second shift register is provided for driving the
`LEDs along the columns. Information is stored in the
`shift registers to effectuate selective driving of selected
`ones of the LEDs.
`
`In accordance with one feature of the present inven-
`tion. the driving circuit includes means for selectively
`applying driving currents of various amplitudes to the
`LEDs so that the LEDs display selected colors.
`In accordance with another feature of the present in-
`vention. means is provided for varying the pulse widths
`of the driving current pulses to selectively vary the in-
`tensity of the display.
`The above and other features of this invention will be
`
`more fully understood from the following detailed de-
`scription and the accompanying drawings. in which:
`HG. 1 is a schematic block diagram of a LED display
`' matrix having a driving circuit in accordance with the
`presently preferred embodiment of the present inven-
`tion;
`
`l0
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60.
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`65
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`FIG. 2 is a diagrammatic representation of wave-
`forms associated with the driving circuit illustrated in
`FIG. 1;
`FIG. 3’is a diagram illustrating the color display char-
`acteristics of a light emitting diode;
`FIG. 4 is a‘schematic block diagram of a logic circuit
`for color control of light emitting diodes in accordance
`with one embodiment of the invention; and
`'
`FIG. 5 is a block logic diagram of a color driving cir-
`cuit for controlling the intensity and the color of dis-
`play of light emitting diodes in accordance with an-
`other embodiment Of the invention.
`
`Referring to FIG. 1 there 'is illustrated a matrix 10
`having m number of leads 11, 11a, etc. arranged in
`rows and n number of leads 12, 12a, etc. arranged in
`‘ columns. Leads 11 and 12 are electrically isolated, and
`are interconnected by a matrix of m n number of light
`emitting diodes 13. For example,’the anode of each
`diode 13 may be connected to a respective lead 11
`while the cathode of the diode may be connected to a
`respective lead 12. Leads 11, 11a, etc. are connected
`through resistors 14, 14a, etc. and integrated circuits
`15, 15a, etc. to individual outputs of m register 16. The
`input for register 16 is connected to the output of shift
`register 17. Leads 12, 12a, etc. are connected through
`transistors 18, 18a, etc. to ground, the base of each
`transistor 18 being connected to a separate output of
`n register 19. As will be more fully understood herein-
`after, circuit 15 may consist of suitable amplifiers or
`driving circuits for color and brightness control, such
`as the circuits illustrated in FIGS. 4 and 5.
`'
`
`Register 19 is a shift register capable of sequencing
`enable signals to the various outputs of the register.
`Shift register 19 has a first input 21 for resetting the
`register and to condition operation of the first transis-
`tor 18. A second input is connected to slave clock 23
`to sequence an enable signal to the outputs of register
`19 to sequentially operate transistors 18, 18a, etc. Reg-
`ister 17 has an input 20 for supplying data to register
`17. The input data may be supplied by means (not
`shown) which develops the input signals in accordance
`with data to be displayed. The input data to register 17
`includes at least one bit for each LED device in matrix
`10. As will be more fully understood hereinafter, the
`input may include more than one bit per LED device
`to achieve color and intensity control.
`Master clock 22, which, as will be more fully ex-
`plained hereinafter is a gated clock, is connected to one
`input of storage register 17 and shift register 16, and is
`connected to an input of slaVe clock 23. The output of
`clock 23 is connected to an input of shift register 19.
`As illustrated in FIG. 1, storage register 17 includes a
`feed-back path 24 connecting the output of the storage
`register to its input.
`With reference to FIG. 2, the operation of the driving
`circuit illustrated in FIG.
`1 may be explained. Light
`emitting diodes ’13 are connected between each lead 12
`and each lead 11 so that connection is made from the
`
`m register 16 through the light emitting diodes 13 and
`transistors 18 to ground. Input data is supplied to stor—
`age register 1-7. The input data to register 17 comprises
`at least m n number of bits of information, where m is
`equal to the capacity of register 16‘ and n is equal to the
`capacity of register 19.‘A's‘will be more fully under-
`stood hereinafter,
`the input data may include some
`multiple of m n bits for color and intensity control.
`With an m by n matrix 10, the input data to storage reg-
`
`,
`
`HTC, Exhibit 1006
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`HTC, Exhibit 1006
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`

`

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`3,909,788
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`4
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`ister 17 corresponds in length to some multiple of the
`number of diodes in matrix 10.
`Master clock 22 is a gated clock capable of produc-
`ing xm pulses 26 (FIG. 2), where m is the number of
`outputs of m register 16 and x is the number of bits as-
`sociated with color and intensity circuits, if any. Upon
`completion of generation of xm pulses, clock 22 is
`gated off for some predetermined period of time. For
`example, clock 22 may include a counter (not shown)
`adapted to count xm pulses generated by the clock.
`The counter may trigger a timer (not shown) which
`gates off clock 22 for a predetermined period of time.
`At the end of the predetermined period of time, the
`timer and counter may be reset and the clock operated
`to produce another xm pulses.
`Input data is supplied to storage register 17 via input
`20. The input data will consist of xmn bits, where n is
`the number of outputs of register 19. With each xm
`clock pulses from clock 22, xm data bits will be for-
`warded to shift register 16 for storage therein. Since
`clock 22 is a gated clock which stops for a period of
`time after each xm pulses, the xm data bits in register
`16 will be stored therein until clock 22 is restarted.
`Master clock 22 also drives slave clock 23 to produce
`a single pulse 25 (FIG. 2) for each xm pulses produced
`by clock 22. Conveniently, the pulse 25 may have a
`period equal to the period of the xm pulses.
`The binary value of each bit of information stored in
`m register 16 operates through integrated circuit 15 to
`control the current on each of leads 11. The presence
`of the n pulse to the input of n register 19 conditions
`the first transistor 18 to conduct. Hence, current flows
`through integrated circuits 15, through the light emit-
`ting diodes, and transistor 18 in accordance with the
`binary value of the signals stored in register 16. For ex-
`ample, if eight rows 11 are connected to register 16,
`and if no color or intensity circuits are associated with
`integrated circuits 15 (so x = l), the xm code will con-
`sist of 8 bits. Each 1 bit in the code stored in register
`16 will supply sufficient current to condition the diodes
`connected to the respective row leads to conduct,
`whereas’those diodes receiving a 0 bit will not be condi-
`tioned to conduction Energization of a selected. tran-
`sistor 18 for each column will complete the conduction
`path for the LEDs so that those LEDs associated with
`the l‘s from register 16 and associated with the particu—
`lar column 12 will be energized.
`,
`>
`Assuming, for example, that the display is to be in
`single color and single intensity (x— l ), during the first
`n pulse 25, m pulses 26 are stored into register 16,
`'Pulse 25 also conditions register 19 to provide an out-
`put to transistor switch 18 to complete a path for all di-
`odes in the first column. The period of conduction for
`transistor 18 is shown at 27 in FIG. 2 and is long com-
`pared to pulse 25. The LEDs remain on during the re-
`mainder of pulse 27, at which time clock 22 conditions
`a new set of 111 pulses 29 to be stored in register 16. At
`the same time, clock 22 drives clock 23 to condition
`shift register 19 to shift to its second output to operate
`transistor switch 18a. Transistor 18a conducts for the
`period illustrated at 30 in FIG. 2.
`If during the first 11 pulse,
`the m pulse pattern is
`11010110 and the integrated circuits are condition to
`respond to only the 1's of the code, it is evident that the
`first, second, fourth, sixth and seventh LEDs of the first
`column will be energized. If during the second 11 pulse,
`the m pulse pattern is 00111010, it is evident that the
`
`5
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`10
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`25
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`65
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`third, fourth. fifth and seventh LEDs of the second col-
`umn will be energized. The pattern continues through
`the entire cycle ofn register 19. The mn pulses are re-
`cycled through register 17 via loop 24 several times. By
`maintaining each cycle sufficiently short, and by recy-
`cling the pulses a sufficient number of times over a suf-
`ficient period of time. the operated LEDs of the matrix
`will appear, to the human eye, to be conducting at the
`same time.
`
`Summarizing the operation of the apparatus shown in
`FIG. I, register 16 is loaded with m pulses. When regis-
`ter 16 is fully loaded, master clock 22 stops, so that all
`the outputs from register 16 remain unchanged for the
`duration of the time interval between the series of m
`
`pulses 26 and the series of m pulses 29. The LEDs are
`energized and provide a display during this period of
`time. It should be noted that although transistor 18 is
`conducting during the period of register 16, the LEDs
`produce no visual effect due to the shortness of each m
`pulse 26. Alternatively, the gate pulse 25 which oper-
`ates transistor 18 may occur at the end of each series
`ofm pulses, or circuits 15 could be gated off during the
`pulse 25 so that the outputs from m register 16 are not
`delivered to the matrix until the register is fully loaded.
`One feature of the present invention resides in the
`utilization of the color emitting capabilities of certain
`light emitting diodes. For example, gallium phosphide
`light emitting diodes available from Bowmar Canada,
`Ltd., when subjected to a low current emit a predomi-
`nantly red light. However, when subjected to a rela-
`tively high current, such diodes emit a predominantly
`green light. The brightness of the red and green hues is
`illustrated in FIG. 3 as a function of current. At low
`currents, the red hue, illustrated by waveform 32 is pre-
`dominate over the green hue, illustrated by waveform
`31, whereas at high current the green hue predomi-
`nates. At cross-over point 33, the hues are about equal
`and will blend to appear as yellow.
`FIGS. 4 and 5 relate to driving circuits to take advan-
`tage of the color phenomenon for selective color dis-
`play from LED matrices. The circuits illustrated in
`FIGS. 4 and 5 may be used for integrated circuits 15 in
`FIG. 1. In FIG. 4, brightness control circuit 34 has out-
`put‘ileads 35, 36. and 37. As will be fully understood
`hereinafter, brightness control 34 provides pulses of
`different pulse widths on the output leads 35, 36 and
`37. Input leads 38 and 39 are connected to a shift regis-
`ter having a length equal to 2 m, since x = 2 to provide
`for conditions for each LED, three colors and off. For
`example, the shift register to which leads 38 and 39 are
`connected is similar to register 16 illustrated in FIG.
`1
`but so arranged so that two bits of information will op-
`erate on the circuit illustrated in FIG. 4. Lead 38 pro-
`vides an input to bistable multivibrator 40, and lead 39
`provides an input to multivibrator 41. Multivibrators
`40 and 41 each have two outputs, output 42 of multivi-
`brator 40 being connected to an input of AND gates 43
`and 44, output 45 of multivibrator 40 being connected
`to one input of AND gate 46, output 47 of multivibra-
`tor 41 being connected to inputs of AND gates 43 and
`46, and output 48 of multivibrator 41 being connected
`to the second input of AND gate 44. AND gate 49 has
`inputs connected to the output lead 35 from brightness
`control circuit 34 and to the output from AND gate 43,
`AND gate 50 has inputs connected to the output 36 of
`brightness control circuit 34 and to the output of AND
`gate 46, and AND gate 51 has inputs connected to out—
`
`' HTC, Exhibit 1006
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`HTC, Exhibit 1006
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`3,909,788
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`put lead 37 from brightness control circuit 34 and to
`the output from AND gate 44. Each of AND gates 49,
`50 and 51 are connected to the base of respective tran—
`sistors 52, 53 and 54. The emitters of transistors 52, 53
`and 54 are connected to respective sources (not
`shown) of constant voltage through resistors, and‘the
`collectors of transistors 52, 53 and 54 are connected
`together to lead 11 of the particular LED row. The
`driving currents established by the voltage sources and
`series resistors are different for each transistor 52, 53
`and 54. For example, the source connected to the emit—
`ter of transistor 52 may produce a relatively high cur-
`rent for green displays, the source connected to emitter
`of transistor 53 may produce a relatively low current
`for red displays, and the source connected to the emit-
`ter of transistor 54 may produce an intermediate cur-
`rent for yellow displays.
`The brightness of a particular LED15 determined by
`the current applied to that diode which also affects the
`color hue. However, the “apparent” brightness of such
`diodes, as perceived by the human eye, is determined
`by the length of time that the diode is emitting light, as
`well as actual brightness. Hence, if it is desirable to pro-
`vide an apparent bright display of red colors, brightness
`control circuit 34 provides pulses of longer duration on
`output lead 36 than the pulses on the leads 35 and 37.
`On the other hand, if it is desired that all colors have
`substantially the same apparent brightness, the length
`of pulses applied to each lead 35-37 is inversely propor-
`tioned to the pulse amplitude so that the average cur-
`rent to each lead is substantially the same. However,
`the pulse lengths may be adjusted somewhat to com-
`pensate for the differing efficiency of the human eye
`for different colors.
`
`In operation of the color driving circuit illustrated in
`FIG. 4, input signals representative of 1’s and 0’s are
`applied to input leads 38 and 39. Multivibrators 40 and
`41 provide output signals at one or the other of their
`outputs depending on the binary value of the input sig-
`nals. For example, if the input signal to lead 38 is a 1,
`multivibrator 40 will provide an output at lead 42,
`where as if the input lead 38 is a 0, multivibrator 40 will
`provide an output at lead 45. Likewise, multivibrator
`41 will provide an output at lead 47 if its input is a 1,
`and will provide an output at lead 48 if its input is a 0.
`AND gates 43, 44 and 46 are arranged so that a 1 1 con—
`dition will operate through AND gate 49 to operate
`transistor 52, whereas a 01 code will operate transistor
`53 and a 10 code will operate transistor 54. A 00 code
`will not operate any of the transistors. Selective opera-
`tion of transistors 52, 53 and 54 provides selective cur-
`rent control to the LED row. If a 11 code is applied to
`leads 38 and 39, gate 49 is operated for a period of time
`determined by the pulse length on lead 35 to operate
`transistor 52 to apply a relatively high current from the
`current source to LED row 11. If a 01 code is applied
`to the input, transistor 53 is operated to drive LED row
`11 with a relatively low current for a period of time de-
`termined by the pulse length on lead 36. An intermedi-
`ate current is applied to row 11 upon operation of AND
`gate 51 and transistor 54 for a period of time depen-
`dent on the pulse length on lead 37.
`FIG. 5 illustrates another color driving circuit which
`provides both a color decoding system as well as auto-
`matic control of the brightness of the particular LED
`being operated. In FIG. 5, information from the storage
`register, such as storage register 17 in FIG. 1 is for-
`
`warded via channel 60 to shift register 61. The code. for
`each LED row includes a 5 digit binary code, the first
`three bitsproviding the brightness code, and the last
`two bits providing the color code. The brightness code
`is capable of selecting seven levels of brightness, as well
`as an off condition. Color decoder 62 is cen‘n‘ected‘ to
`shift register 61 to receive the two bits representative
`of the color code. Color decoder 62, which may be sim-
`ilar to that illustrated in FIG. 4, decodes the two 'bit
`color code and provides an output to a selected one of
`AND gates 63, 64 and 65. The output of AND gates 63,
`64 and 65 are connected to lead 11 of the LED row
`being operated.
`Decoder 661s connected to the output of register 67
`which in turn is connected to receive the three bit
`
`brightness code from shift register 61. Register 67 op-
`erates on the brightness, or gray scale code, by stepping
`the code until a 111 code is reached. The stepping 0c-
`curs at a rate dependent upon the rate of clock pulses
`on lead 68. Decoder 66 will provide an output pulse for
`each pulse necessary to step the gray scale code to a
`111 condition. Decoder 66 is connected to AND gate
`69 which, in turn, is connected to monostable multivi~
`brator 70. The output of monostable multivibrator is
`connected to a second input of each of AND gates 63,
`64 and 65.
`
`10
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`15
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`20
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`25
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`30
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`35
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`In operation of the apparatus illustrated in FIG. 5, a
`five bit code is applied to shift register 61 in accor~
`dance with a signal from the data storage over lead 60.
`The input signal is clocked into register 61 via lead 71.
`Two of the bits of the code are decoded by color de-
`coder 62 to selectively enable one of AND gates 63,64
`and 65. AND gates 63,64 and 65 include current driv-
`ing means (not shown in FIG. 5) for deriving separate
`driving currents for each AND gate. For example,
`AND gates 63-65 may include transistor switch means
`and separate current sources as described and illus-
`trated in connection with FIG. 4. In the even that, gate
`63 is operated, a relatively high current is supplied to
`40
`v the LED row so that the LEDs will emit a green color.
`If AND gate 64 is operated, a relatively low current is
`provided to lead 1 1 so that the LEDs will provide a red
`display. If AND gate 65 is operated, an intermediate
`current is provided to lead 11 to provide a yellow dis—
`play. The duration of operation of a. particular AND
`gate 63, 64 and 65 is determined by register 67, de—
`coder 66 and monostable multivibrator 70.
`
`45
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`50
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`55
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`60
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`65
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`Decoder 66 decodes the three bit gray scale code by
`stepping the code to a 111 condition and providing out-
`put pulses for each step. For example, if the three bit
`gray scale code is 110, clock 68 operates on register 67
`only once to step the code to 1 11. Hence, a single pulse
`is passed by decoder 66 to AND gate 69 and thence to
`monostable multivibrator 70. Multivibrator 70 is oper-
`ated once to provide a single pulse, whose duration is
`determined by the time constant of the multivibrator,
`to the operated AND gate 63-65. Hence, the selected
`AND gate 63-65 (selected by the color code) is oper-
`ated during the single pulse to provide a current output
`of selected magnitude and selectively short duration.
`However, if the gray scale code is 000, clock 68 must
`step through seven cycles to shift register 67 to its 1 l 1
`position. The seven pulses are passed through decoder
`66 and AND gate 69 to monostable multivibrator 70 to
`operate the monostable multivibrator 70 seven times to
`provide seven successive pulses to the operated AND
`gate. The LEDs operated on the LED row 11 are oper-
`
`HTC, Exhibit 1006- -
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`HTC, Exhibit 1006
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`ated for seven successive pulses to provide‘th'efappear-
`ance of a relatively long. duration of “on” condition.
`Hence, the display is perceived by a human as being
`brighter utilizing a greater number of successive pulses
`in the decoded gray scale code as opposed to less nu—
`merous pulses. (A 111 input code will not be stepped,
`so multivibrator 70 will not be operated. Hence, a 111
`input code represents an “off” condition for the partic-
`ular LED row.)
`The apparatus illustrated in FIG. 5 is particularly ad—
`vantageous where it is desirable to selectively control
`the apparent brightness of a display. For example, in
`the event that it is desirable to provide a warning indi-
`cation, it may be desirable to display such warning in
`a red color and with a relatively intense brightness.
`With the apparatus illustrated in FIG. 5, it is possible
`to operate the LEDs from a relatively low intensity
`green display to a relatively high intensity red display
`merely by altering the code from the computer storage
`memory.
`The present invention thus provides apparatus for
`driving LEDs for selective brightness as well as selec-
`tive color. The apparatus is effective in operation and
`provides a wide variety of uses.
`This invention is not to be limited by the embodi-
`ments shown in the drawings and described in the de—
`scription, which are given by way of example and not
`of limitation, but only in accordance with the scope of
`the appended claims.
`What is claimed is:
`
`1. Apparatus for driving selected ones of m times n
`light emitting diodes where m and n are whole num—
`bers, comprising: first register means having at least m
`outputs and second register means having n outputs,
`each output of said first register means being con-
`nected to one side of one diode in each of n mutually
`exclusive groups of diodes and each output of said sec-
`ond register means being connected to the other side
`of one diode in each of m mutually exclusive groups of
`diodes, each diode being in one of said groups of m di-
`odes and in one of said groups of n diodes; storage
`means connected to said first register means for storing
`at-least In times n bits representative of information to
`be displayed, said storage means having a feedback
`path for recycling m times n bits, first clock circuit
`means connected to said storage means and to said first
`register means, said first clock circuit means generating
`at least m clock pulses for controlling transfer from said
`storage means of successive binary codes containing at
`least m bits of data to said first register means for con-
`ditioning selected groups of said m groups of diodes for
`conduction, means for gating said first clock circuit
`means off for a predetermined period of time after gen-
`eration of at least m clock pulses, and second clock cir-
`cuit means driven by and responsive to said first clock
`circuit means and connected to said second register
`means, said second clock circuit means generating a
`single clock pulse substantially equal in duration to the
`total period of m clock pulses generated by said first
`clock circuit means for conditioning a group of said n
`groups of diodes for conduction, diodes existing in both
`the selected groups of m diodes and the selected group
`of n diodes being operated for said predetermined per-
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`iod of time, said first and second clock circuit means
`restarting after said predetermined period of time and
`recycling said storage means m times n bits to repeat
`the pattern of operating said diodes.
`2. Apparatus according to claim 1 wherein said first
`register means includes m current source means con-
`nected to respective outputs of said first register means,
`each of said current source means being conditioned by
`said first register means to provide a predetermined
`current to the diodes of a respective group of n diodes.
`3. Apparatus according to claim 2 wherein said sec-
`ond register means includes n switch means connected
`to respective outputs of said second register means,
`each of said switch means providing a current path be-
`tween the diodes of the respective group of m diodes
`and said current source means.
`
`4. Apparatus according to claim 2 wherein said di-
`odes are characterized by emitting predominantly dif—
`ferent color hues when driven by respectively different
`currents, and wherein each of said current source
`means includes a plurality of current sources each
`adapted to supply a current of mutually different pre-
`determined magnitudes, and means responsive to the
`binary code in said first register means for selectively
`connecting on of said current sources to the respective
`group of n diodes.
`5. Apparatus according to claim 4 wherein the binary
`code transferred to said first register means contains at
`least 2 m bits, and each of said current source means
`includes decoder means for decoding 2 bits of said bi—
`nary code in said first register means to selectively op-
`erate said current sources.
`6. Apparatus according to claim 4 further including
`brightness control means for operating said current
`sources for a predetermined period of time.
`7. Apparatus according to claim 6 wherein said
`brightness control means comprises means responsive
`to a predetermined code in said first register means for
`controlling the duration of time that current from the
`selected current source is applied to the respective
`group of n diodes.
`8. Apparatus according to claim 6 wherein said bi—
`nary code transferred to said first register means con-
`tains at least 5 m bits, said current source means includ-
`ing first decoder means for decoding 2 of said bits to
`selectively operate said current sources and said bright-
`ness control means including second decoder means
`for decoding 3 of said bits for selectively controlling the
`duration of operation of said selected diodes.
`9. Apparatus according to claim 1 wherein said first
`register means produces x m output bits, m number of
`circuit means each responsive to mutually exclusive x
`number of bits for producing driving currents each hav-
`ing a current amplitude dependent upon the bit pattern
`of said respective x number of bits, and means connect-
`ing each of said circuit means to respective ones of said
`groups of n diodes.
`10. Apparatus according to claim 9 wherein each of
`said circuit means is responsive to a respective x num-
`ber of bits to produce a driving pulse having a current
`amplitude and a time duration dependent upon the bit
`pattern of said respective x number of bits.
`*
`a:
`*
`*
`*
`
`HTC, Exhibit 1006
`
`HTC, Exhibit 1006
`
`