Electronic rule for precise distance measurement and distance setting
Contents
1. 10 15 no display for RTS SUBROUTINE NAME SCAN FUNCTION To display both DISPLAY and SCALE once then check if any key is depressed The routine will set A to 0 if and only if it finds that no key is depressed Load X register with 0977 pointing to left most digit of Load A with appro priate digit of rightmost digit of DISPLAY JSR CONV SUBROUTINE NAME ONEROW FUNCTION This routine checks one row of the KEYBOARD to see if any key is depressed When no key is found depressed it will set A to be 0 If a key is found depressed 4 158 229 33 continued lt RP Turn off DISPLAY Set PAO PA6 of 6530 X back to input lines XX register 1 Y register 3 Y register Y register 1 Y register 0 continued will be set equal to 1 Note that when performing I O 65 3 depressed key is read as a 0 and nondepressed key is read as a 1 Therefore a compliment operation is needed The variable i which is in X register stores the row number to be checked plus 1 The routine will the bit position corresponding to the key in that row always increment i 35 continued Set pin i of com ponent I8 74145 low to check i 1 row of KEYBOARD bit pattern 0 46 Is every bit of Pa0 6 high a key is depressed lt A FFg exclusive for comp2. The foregoing objects features and advantages of the present invention will be made clear along with other advantages features and objects thereof by reading the specification along with the drawings wherein like numbers designate like objects throughout FIG 1 shows an apparatus embodying the present invention FIG 2 illustrates the internal components of the pres ently preferred embodiment and the electrical intercon nections therebetween FIG 3 shows the electrical connections for the board and display of the invention FIG 4 shows the electrical connections to the scale of the invention FIG 5 shows a circuit diagram of supporting logic used within the invention FIG 6 is a flow chart illustrating the interaction between the operator and the inventive apparatus DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG 1 illustrates a preferred embodiment of the elec tronic rule Three major elements of the device are shown an optically active LED scale 10 a digital nu meric display 20 and a keyboard 30 The keyboard comprises a plurality of keys 32 including keys for numerical entry and function keys The electronic rule disclosed herein can be used to perform length measurement or distance setting In performing a measurement of distance or length a lin ear distance between the left and right endpoints of an object is determined In distance setting the user speci fies a measurement unit and a num
3. The input lines 62 to decoder 60 are connected to the peripheral bus for connection to pins PB1 PB4 of unit 42 Additional output lines 64 from decoder 60 are con nected to the three rows of the keyboard in the pres ently preferred embodiment Pins 0 6 of unit 42 are connected to the columns of the keyboard and also through open collector inverters 66 to display units 51 56 Under control of the operating program display 20 is activated by scanning the several display elements The scan is achieved by the proper coding of pins PB1 PB4 resulting in sequential selection of transistors Q1 Q6 by the action of decoder 60 For each selected transistor 4 158 229 5 and correspondingly selected display element the num ber to be displayed is obtained from a table in unit 42 and converted to a code suitable for seven segment display which is placed in a register Pins 0 caused by the program to act as output pins convey the proper seven segment code to the display element The operating program also selects the proper scale ele ments to display RP and X After performing its display function the operating program causes keyboard 30 to be scanned Keyboard scanning is achieved by providing sequen tially the codes for activating output lines 00 02 of decoder 60 The codes are applied sequentially by pins PB1 PB4 of unit 42 For each code one of lines 00 02 is chosen and one of rows 0 2 of keyboard 30 is acti va
4. 4 158 229 15 c ntinued 3 E 8 8 8 2 E 2 2 2 2 4 158 229 17 18 continued Yes No CP Key Set CPMODE to 1 RP Key RP XCUR Set sign byte of D to 10 for 4 158 229 19 continued ignore Key ignore Key INUSELAG 1 Set sign byte of D to be 13 to display F key Yes No UNITSIGN 0 UNITSIGN 1 JSR ELIPSIGN C Key 4 XCUR RP Set sign byte of D to 10 for 20 4 158 229 21 22 continued CM key INCM lt 12 to display CM inch byte of D to 10 Set sig Set sign byte of D to be 13 in Key 4 4 158 229 23 24 continued X register is a hardware Key X register lt XCUR register in the microprocessor 40 It is used as a temporary Storage X register X register 1 X register gt TOTAL JSR ERROR Key Mss X register XCUR X register X register 1 XCUR X register Sign byte of D 13 for minus SIKI X lt RP DA RP XCUR oad dividend X gt RP Sign byte of D 10 for positive DA XCUR RP oad dividend Divide DB UNIT oad divisor JSR DIVD 4 158 229 25 26 continued JSR BCD JSR FLIPSIGN FLIPSIGN FLIPSIGN X RP Sign byte of D lt 10 for positive 0 9 Key A
5. 7 segment code for 2 entry 3 7 segment code for 3 entry 4 7 code for 4 entry 5 7 segment code for 5 entry 6 7 segment code for 6 entry 7 7 segment code for 7 entry 8 7 segment code for 8 entry 9 7 segment code for 9 entry 10 7 segment code for No display null entry 11 7 segment code for i entry 12 7 segment code for entry 13 7 segment code for ABOUT SIGN CONVENTION 1 By default if RP then the distance is displayed as positive If X lt RP then it is negative X is the cursor position 2 The user can reverse this convention by hitting the F key This will cause no change in the positions of RP and X per se But this will cause the reversal of the signs Hitting the F key again will return to the default convention X is the cursor position 3 The minus key by itself does not reverse the sign convention It merely causes the minus sign to be displayed 4 During the distance setting operation one can depress the minus key followed by a series of nu meric keys to cause the distance to be displayed The following possibilities may occur in a distance setting operation X is the cursor position Minus key Sign convention depressed Relative positions of RP X default UNITSIGN 0 YES X to the left of RP default UNITSIGN 0 NO X to the right of RP reverse UNITSIGN 1 YES X to the right of RP reverse UNITSIGN 1 NO X
6. a refer ence point and a cursor having positions which are determined by keyboard entries and are displayed nu merically 28 Claims 6 Drawing Figures U S Patent Jun 12 1979 Sheet 1 of 5 4 158 229 Move cursor O 956 U x RP o U S Patent Jun 12 1979 Sheet 2 ofS 4 158 229 2 z 40 em 66 MPS 6502 d e SUPFORT SYNC L 06 SV ND Jb XTAL EI 02 ag 00 S S d lo ENS WIN RO 9 d 0000 N ABIO S a 4810 2 Voc IN fL 48 ABI 2 2 CONTKOL 47 BUS DATA BUS 6530 X 080 087 24 083 7 27 ADDRESS BUS 460 ABI 17192534 257 44 0 40 28 Ar 7 24 244137 3 A 26 SCALE 4 54 22 PANSE 2 13 25 27 71921 22 732425 lul U S Patent Jun 12 1979 Sheet 3 of 5 4 158 229 62 60 5 PBI A z Peal lp peal Dm lt 5 ss S MCS 6230 PERIPHERAL BUS AU 44 KOW MCS 6550 PERIPHER Aly 0W 2 BUS OO PAS 2 PAO s ee U S Patent Jun 12 1979 Sheet 4 of 5 4 158 229 Re E A B re 4 70 6 DECODER dr 74 54 62 OT 2 2 4566 T8 248 CDE AM 2 diiiiinins ala a a a aa a aa old lal Lddddddddddddad PEPPE PPE 0 lt Bes 4 Y 5 SMS NEM Ee ES Gy S 5 A
7. distance to be displayed represented in BCD form with each segment of 4 bits 35 for a decimal digit The leftmost byte of D called sign byte of D stores the sign or no display for of the distance All segments are index pointers to TABLE INCM An index pointer to TABLE 11 for i 40 inch 12 for c cm or 10 for null UNITSIGN Sign of UNIT either 1 for negative or 0 for positive UNIT Unit factor indicating the number of lights for each basic measurement unit selected by the user CPMODE A flag indicating whether the user is defining his own measurement unit either 1 for CP mode or 0 for distance setting DIGIT The most recent digit entered by the 45 user 50 MINUSFLAG A flag indicating whether the user has depressed the key either 1 for depressed or 0 otherwise DIGIT Number of digits entered by the user FLAG A flag indicating whether the user 55 has depressed the key decimal point either 1 for depressed or 0 otherwise SUM Integer portion of the number entered by the user FSUM Fractional portion of the number 60 entered by the user DA DB Q Dividend divisor and quotient respectively MA MB P Multiplicand multiplier and product respectively 65 Constants located in ROM INFACTOR Number of lights for one inch CMFACTOR Number of lights for one cm integer or fractional portion TABLE 0 7 segment code for 0 entry 1 7 segment code for 1 entry 2
8. embodiment contemplates the use of 121 ele ments in scale 10 it is clear that with no modification of hardware design the eight output lines from LSI unit 44 in conjunction with decoders 68 and 70 may equally address 256 components of a scale Similarly with slight modification such as increasing the storage avail able to unit 44 and with the use of different decoders 68 and 70 virtually any number of elements may be incor porated within the scale In the presently preferred embodiment two elements are activated to display two points Conceivably scale displays of more than two elements or of variable numbers of elements or of a fixed number of variable elements may be desired For any of these possibilities the elements to be activated may be selected either by scanning and multiplexing elements along a row or by simultaneous activation of all selected elements The preferred embodiment pro vides multiplexed activation of the LED s selected to represent RP and X Turning now to FIG 5 the supporting logic shown in FIG 2 is illustrated as comprising a timer 72 con nected to CPU 40 as well as to LSI units 42 and 44 Additionally a crystal circuit is utilized in the timing connections thereby providing a separate phase for the logic circuitry In operation the use of an optically active scale per mits inter alia provision of a standout optical contrast for the endpoint optical elements in comparison with the interval being me
9. means for a plurality of said control means functions of activating elements of said scale means displaying numeric representations of distances on said display means and responding to said input means 7 The apparatus as recited in claim 5 wherein said control means activates at least two elements to provide indices for distance measurement 8 The apparatus as recited in claim 7 wherein said indices provided optically active identification of end points of a distance to be measured 9 The apparatus as recited in claim 7 wherein said control means activates a plurality of adjacent elements to provide identification of a distance along said acti vated elements 10 The apparatus as recited in claim 1 wherein said control means comprises digital computer means 4 158 229 39 11 The apparatus as recited claim 1 wherein said input means comprises means for selecting a scale factor for displaying a numerical representation of the mea sured distance 12 The apparatus as recited in claim 1 further com prising means for distance setting whereby an operator enters a selected distance via said input means and said control means activates at least one element of said scale means thereby displaying said selected distance on said scale means and b causes said display means to display a numerical representation of said selected distance 13 Distance setting apparatus for delineating a se lected distance comp
10. to a precision of tenths of centimeters the meter stick is used Although this is the classical and time honored method of measurement it is not entirely satisfactory The user must overcome errors associated with parallax and interpolation between scale divisions Furthermore the scale markings are fixed and conver sion to other systems of units must be done as a separate operation introducing additional errors Previous de vices competing with the meter stick have used me chanical switching of electrical current in an electrical resistor to perform measurements of length Gallacher et al U S Pat No 3 973 326 is illustrative of such a prior art device having a cursor on a movable wand and a resistor extending along the length of the wand An electrical contact on the cursor contacts the resistor thereby forming a potentiometer with an out put which is variable with cursor position A digital voltmeter provides an indication of the distance mea sured Such devices are cumbersome to use and the mechanical switching mechanisms cause reliability problems Moreover prior devices for performing ordi nary measurements of length have not been directly coupled to electronic calculating devices so as to pro vide convenience and the greater power of electronic arithmetic The use of light sensing elements particularly fiber optics to determine distances in conjunction with counters and stored program computers is disclosed in Rempert U
11. 63rd the operator would follow the procedure outlined above and after turning on the device move the cursor to the right until it is adjacent to one of the object endpoints for example the left endpoint at LED 10 Depressing the RP button will select that position as the reference point Since the distance is desired in centimeters the user may depress the button which moves the cursor one centimeter to the right and displays a 1 in the digital display Further depressing the button to move the cursor to the right to the 63rd LED in this example the user then observes the distance in centime ters on the numerical display Were the user to desire a measurement in some arbi trary scale as would be the case in reading a map for example and assuming the distance is still between the 10th and 63rd LED the following procedure will be followed After selecting the reference point the cursor is moved to the right from the reference point a particu lar distance In the case of map reading the cursor is moved to the right by a distance corresponding to the particular map scale factor Thus where inch equals one mile and a map scale is provided the cursor may be moved to the right by 4 inch At this point the button is depressed and the numerical value being mea sured is entered In this example the number 1 would be entered if the desired distance is in miles Depressing of the button indicates the calibration distance as bein
12. S Pat No 3 598 978 However relative movement is required between the object and the light sensing element and the device does not operate as a replacement for a ruler or meter stick having a scale thereon Scales are utilized in Zipin U S Pat No 3 748 043 but only for viewing by photosensors to de termine a more accurate measurement by interpolation A display is provided for the determined distance which is however not under operator control with respect to either scale factor or other functions Other devices are known for distance measurement by optical means as illustrated by Renner et al U S Pat No 3 965 340 and Kimura U S Pat No 3 784 833 Such devices require the use of gratings to effect light measurement Renner et al for example detects a change in light transmission due to a relative displace ment between a fixed interference grating on a fixed caliper and a movable grating on a movable caliper The changed light transmission is detected to provide 15 20 25 30 40 2 an indication thereof on an associated calculator Kimura requires a diffraction grating to effect light measurement utilizing LED s and photodetectors by affixing the detectors directly to the rear of an index grating Such devices rely on complicated optical in strumentation and do not provide for ordinary scale measurements of distances of either commonplace or arbitrary scale factors Lewis U S Pat No 3 515 888 uses a reti
13. Thus once a reference point is determined the inch or centimeter button may be depressed or an arbitrary unit may be entered by moving the cursor to a calibration distance and entering the numerical value of that distance The third phase of distance setting however requires entry of a number and depressing the button Thus in the map exam ple previously used once the scale had been entered as 4 158 229 4 inch per ten miles for example by displacing the cursor 4 inch from the reference point and by depress ing the button followed by entry of the number 10 from the keyboard and by depressing of the button the user may choose to display a distance repre sentative of 42 5 miles To do this the number 42 5 would be entered by the keyboard the depressed and the cursor would be moved by the operating pro gram to 42 5 miles st a scale of 4 per ten miles from the reference point The user would then have the reference point and cursor separated by the distance equivalent to 42 5 miles at that scale factor The software used to support the functions of the electronic rule is the operating program The program is stored in the two 1 K byte ROM of the MCS 6530 chipes Basically the program follows the flow of con trol as shown in FIG 6 The primary concept used in monitoring the key board and in driving the LED s in scale display is to alternate between reading the keyboard and writing to the display and scale at s
14. United States Patent ri Woo Jr et al 54 76 21 22 51 52 58 56 3 594 783 3 765 764 3 ELECTRONIC RULE FOR PRECISE DISTANCE MEASUREMENT AND DISTANCE SETTING Inventors John Woo Jr 112 Teakwood Dr Huntsville Ala 35801 Yeong Chung E Lien 3036 Yellowstone Dr Lawrence Kans 66044 Appl No 809 772 Filed Jun 24 1977 Int 1 2 G01C 3 00 G01B 11 02 U S Ch 364 562 33 125 A 33 1 L 356 396 Field of Search 364 561 562 33 125 A 33 1 L DIG 3 250 202 356 156 170 References Cited U S PATENT DOCUMENTS 7 1971 Bullock 364 561 X Niss 356 156 11 4 158 229 45 Jun 12 1979 3 872 288 3 1975 Sampey eee 364 561 3 955 073 5 1976 Carew et al 364 561 3 965 340 6 1976 Renner et al 235 151 32 Primary Examiner Edward J Wise Attorney Agent or Firm Schwartz Jeffery Schwaab Mack Blumenthal amp Koch 57 ABSTRACT An instrument for precise measurement and setting of distances has an electronically controlled scale compris ing optically active elements an electronically con trolled digital display and a keyboard The display and keyboard are mechanically rotatable and connected by electronic circuitry including a microprocessor The light scale provides optical indicia including
15. asured That is while the two LED s at the endpoints of a line interval being mea sured are activated remaining diodes are not and the endpoints only are made conspicuous thereby decreas ing the chance for measurement error The system may similarly operate by activating the optical elements along the entire interval or by activating all elements except those along the interval being measured rather than only the endpoint elements Either of these alterna tives also provides enhanced contrast and reduction in measurement error In performing a measurement three phases of operator machine interaction are contem plated The following discussion may best be under stood with reference to FIG 6 where circles corre spond to operations by the user and rectangles to values of registers internal to the apparatus In a first phase a reference point is selected As dis cussed above only two scale positions are activated The two positions may coincide One position is called the reference point hereinafter RP and the other is called the cursor or X When the power is turned on RP is automatically set to the left margin of the LED scale and the cursor position will be the same as RP When the buttons and are depressed the cursor position will be changed The new cursor posi tion depends on the previous cursor position the button depressed and the length of time a button remains de pressed The cursor position will propagate to the ri
16. cle assembly to determine position change with respect to a fixed reference by using optical gratings for chopping a light beam Niss U S Pat No 3 765 764 uses light deflecting means for coordinate measurements source projects light onto a movable deflecting means thence to a fur ther measuring point Grendelmeier U S Pat No 3 599 004 determines scale placement utilizing equi spaced photocells A differential amplifier is used to permit measurement of displacements less than the cell size Such devices while utilizing light sensing means do not provide a portable means under operator con trol for obtaining distance measurement comparable to ordinary meter stick manual measurement nor do the devices provide for variation of a scale factor under operator control Moreover the prior art devices do not contemplate the use of an optically active scale for distance setting and measurement SUMMARY OF THE INVENTION The present invention overcomes the disadvantages of the prior art and provides distance measurement and setting utilizing an optically active scale In accordance with the invention a high resolution distance measure ment device is provided for measurement in the British system the Metric system or in any other user defined system of measurement apparatus disclosed herein provides a digital numeric display of the measurement to the user as well as displaying a length when the numeric distance and basic measu
17. d repeatedly When a depressed key is detected its function is then executed by EXEC If an error is detected ERROR routine will flash the display which can only be cleared by pushing the key Each time the key is depressed the electronic rule is initialized and the operating program re started The various subroutines outlined above are shown in flow chart format in Appendix A and B APPENDIX A OPERATING PROGRAM DESCRIPTION Background 1 When the power is turned on and the key is depressed an RST Reset interrupt is generated which will start the operating program Each 6530 chip includes a 1024 byte Read only Memory ROM The operating program is to be stored permanently in the 2048 bytes of ROM in the two 6530 chips 6530 X and 6530 Y Each 6530 chip includes a 64 byte Random Access Memory RAM The total 128 bytes of RAM is to be used for 2 the storage area of the stack to be used by the microprocessor 6502 to save return addresses in subroutine calls and b the data areas storing data variables related to the user opera tions The data variables related to the item b are listed under Data Constants and Variables 4 In the flow chart description of the operating pro gram JSR XXX is used to mean Jump to sub routine whose name is This has the affect of saving the return address RA in the stack which is mentioned in 3 a above The symbol RTS is used to mean return from subrouti
18. disclosure will be apparent to those of ordinary skill in the art Such variations do not depart from the spirit of the invention and are included within the scope of the appended claims What is claimed is 1 Apparatus for distance measurement comprising a optically active scale means having a plurality of optically active elements for measuring a distance b numerical display means for displaying a numeri cal representation of the distance measured c means for providing operator input and d control means responsive to said input means and connected to scale means and display means for activating at least one element of said scale means and for causing said display means to display a numerical representation of the distance measured along said scale means by said at least one activated element 2 The apparatus recited in claim 1 wherein said scale means comprises a plurality of light emitting diodes 3 The apparatus recited in claim 1 wherein said scale means comprises a plurality of liquid crystal elements 4 The apparatus recited in claim 1 wherein said nu merical display comprises a plurality of seven segment display elements 5 The apparatus as recited in claim 1 wherein said input means comprises a keyboard having a plurality of keys representative of plural numerical values and of plural functions for execution by said control means 6 The apparatus as recited in claim 5 further compris ing multiplexing
19. en RP and the cursor position in the units specified by the user is j In both the length measuring and the distance setting processes RP is defaulted to the leftmost end of the rule if the user chooses not to set his own RP position The measurement unit is defaulted to the distance between two neighboring LED lights if the user does not specify his own In FIG 6 the control sequences described above are summarized as a flow chart At each circle the specific user operation represented by the circle will cause the actions described in the associated rectangle Each circled operation represents pressing of the simi larly labeled button by the user on the keyboard The registers represented by the rectangles include RP position of the reference point X position of cursor D number displayed U the unit conversion factor in terms of number of LED s IN CM constant unit conversion factor for inch or centimeter Any sequence of operations not included in the flow chart will be considered illegal The display will blink all the seven segment lights when an illegal operation is detected The user can press to clear the display In 5 45 60 65 8 this case RP and the measurement unit will not be changed As an illustrative example where it is desired to de termine the length in centimeters of an object the scale is placed against the object If the object extends for example from the 10th LED through the
20. erical value d The electronic rule will then select two points so that the distance between them is d These operations are de fined and further described in conjunction with FIG 6 infra Turning now to FIG 2 the various components utilized in the preferred embodiment and the intercon nection thereof are shown as including a microproces sor chip 40 such as is available from MOS Technology Inc of Norristown Pa under the nomenclature MPS 6502 and two peripheral interface memory units of large scale integraton LSI chips available from MOS Technology as chips MCS 6530 shown at 42 and 44 Each LSI unit includes two input output registers two peripheral data buffers an interval timer two data con trol registers an address decoder a data bus buffer a chip select unit and two memory units a mask program mable 10248 ROM and a 64X8 static RAM These units as well as the microprocessor unit are described in Appendices G and H in MOS Technology 1 User Manual Support logic unit 46 shown more fully in FIG 5 is connected to the microprocessor and LSI units Unit 42 interfaces with both keyboard 30 and a seven segment display 20 shown combined in block 45 Unit 44 is used to interface with scale 10 A bus structure is utilized for communicating be tween the various units as follows An address bus 47 having lines 0 11 therein communicates between microprocessor 40 and units 42 and 44 Additionally li
21. g 1 unit Finally with the scale against the distance being measured the cursor is displaced to the 63rd LED and the position between the reference point and cursor is displayed numerically in miles As a further example of the effectiveness of the present invention in a map scale having inch equivalent to ten miles the calibration step described above would be modified by entry of the number 10 rather than 1 from the keyboard after depressing the button The display would then provide the distance in miles Clearly the scale need not provide a linear measure ment Thus it is contemplated that scales having opti cally active components which are themselves non lin early distributed along the scales may be used The elements may be logarithmically spaced for example Similarly the elements may be linearly spaced but the measurement phases under the control of the operating program may provide displays corresponding to non linear distances Thus for example the exact distance along a logarithmic chart might be measured using the present electronic rule under a logarithmic subroutine in the operating program Additionally it is recognized that the scale need not be linear but may be curved and may for example be provided along a French curve As an example of the distance setting procedure a user may follow Phases 1 and 2 as previously outlined and may provide a distance either in centimeters inches or some arbitrary unit
22. ght or left as long as or gt is depressed When the user positions the cursor adjacent to one endpoint A of the object to be measured may be depressed to indicate that this position has been selected as the new RP The light for the old RP will be turned off and until the next time RP is changed any later measure ment will be relative to this point That is a distance to the left of RP will be displayed as a negative number on the digital numerical display and a distance to the right as positive The convention can be reversed by depress ing flip sign key When is depressed twice the default convention will be used It is noted that the 4 158 229 7 user can also choose to physically translate the whole rule so that any lighted LED can serve as the RP Having determined a new RP the cursor is moved to a second endpoint of the object to be measured and the distance between RP and cursor displayed It is possi ble however that different measurement units might be desired by the user Accordingly a second phase is provided wherein the specific unit to be used is deter mined When entering the second phase the cursor position coincides with RP If the user selects a conven tional distance unit such as inches or centimeters he can depress IN or which will move the cursor position to the right by one inch or one centime ter The display will have a value 1 If the units are arbitrary then the calibration poi
23. has the key number DIGIT A DIGIT gt BOUND JSR ERROR integer portion fractional portion 4 158 229 27 28 continued FSUM P DIGIT FSUM 0 JSR_BCD BCD Key distance setting ositive ui negative default sign re conven versed de reversed 4 1 sign vention sign convention Right JSR ERROR XCUR A XCUR A 4 158 229 29 30 continued INCM 10 set unit display to be null XCUR RP negative positive UNITSIGN 1 UNITSIGN 1 UNITSIGN 0 DB SUM FSUM Cleanup JSR APPENDIX B continued APPENDIX B 50 _______ SUBROUTINE FUNCTION to initialize data variables and input output pins of 6530 chips is a different entry point 55 to be input lines Set PAO PA7 of 6530 Y to be output lines Set PBI PB4 6530 X 65 to be output lines as Output 06g to PB of 6530 so that pins 1 2 3 5 6 7 9 10 11 of 18 are all high ready for keyboard input 4 158 229 31 32 APPENDIX B continued APPENDIX B continued 0 INCM 10 XCUR 0 UNITSIGN 0 5 D0 CPMODE 0 10 MINUSFLAG 0 UNIT 1 DIGIT 0 FLAG 0 Sign byte of D
24. interrupt to the MPS 6502 When the RST interrupt occurs when the user of the electronic rule pushes the RS key the microprocessor fetches from a fixed location in the operating program an address which points to the be ginning of the operating program The address is loaded into the program counter and execution of the operating program begins As previously mentioned each of the two MCS 6530 chips contains 64 bytes of RAM 1K bytes of ROM and 64 locations for input output ports and timers The RAM portion is used to store variable data such as user defined measuring units digits to be displayed locations of the reference point RP and cursor X etc The RAM is also used by the microprocessor as the system stack Each I O port in a MCS 6530 chip is associated with an I O data register and an I O direction register Both registers can be accessed by providing a unique address which is part of the entire memory address space That is the I O ports are treated like memory storage loca tions Referring now to FIG 3 the keyboard 30 and display 20 are shown in greater detail Specifically seven seg ment display units 51 56 are shown each being driven by lines 57 A specific display element is chosen for activation by one of transistors Q1 Q6 activated and deactivated by signals output by decoder 60 Decoder 60 comprises a BCD to decimal decoder such as com monly available under the designation SN 74145 from Texas Instruments
25. liment opera tion SUBROUTINE NAME FUNCTION CONV convert a decimal digit to a 7 segment code using a conversion table TABLE also display one digit onto DISPLAY The accumulator A has the actual digit to be displayed The X register has the digit number of DISPLAY Use A to select the appropriate entry of the conversion table TABLE to sele Put the selected 7 segment code in A Output X register to PB1 4 of 6530 X to select one digit of DISPLAY 10 15 20 25 30 35 40 45 50 55 65 4 158 229 36 continued Output A 0 6 of 6530 X to select segments Increment X register by 2 to point to the next digit of RTS SUBROUTINE NAME FUNCTION LED To turn on one light in the SCALE the accumulator stores the address of the light Output contents of A to PA pins of 6530 Y Wait for at least 2 msec SUBROUTINE NAME KEY FUNCTION To find out the number I corresponding to the key depressed KEY KEY NUMBER 009 00g to O97 IN OAH CM OBy OCH OFy lt 7 gt lly 12g RP 13g CP 14g KEY TO NUMBER CONVERSION TABLE 4 158 229 37 continued Next 10 15 Use row number 1 2 and bit pattern in to compute key number see the CONVERSION 20 lt Key Number 25 no key is found 30 SUBROUTINE NAME FLIPSIGN FUNCTION To change the dis
26. ne which is the last instruction in execution in a subroutine and has the effect of directing the control to the address RA saved on the top of the stack as well as pop ping RA off the stack The entire operating program is described as a collection of routines with each routine repre sented as a flow chart An italic name followed by a colon is used as a label for the nearest statement DISPLAY KEYBOARD and SCALE refer to the three corresponding components of the Elec tronic Rule All numbers are in decimal unless specified other wise Hexadecimal numbers are indicated with a subscript H N w b Ba Beginning of routine name of the routine is enclosed 7 4 158 229 11 12 continued continued action a program statement TOTAL Total number of lights in SCALE BOUND Maximum number of digits user can enter 5 A decision box lt gt 10 Branching of control the d subroutine calls and returns 15 to statement the destination is indicated inside the circle 20 10 A is the accumulator of the 6502 microprocessor 18 is BCD decimal decoder 60 shown in FIG 3 DATA CONSTANTS AND VARIABLES Note The size number of bytes of the variables or 25 constants is not specified Variables located in RAM Reference point position 30 XCUR same as X in the previous Cursor position discussion D Numerical value of the
27. nes AB10 and AB11 therein communicate with sup port logic 46 A data bus 48 containing lines DB0 DB7 therein further provides communication between the microprocessor and the two LSI units Peripheral pins 10 20 25 30 35 40 45 50 55 65 4 PAO PA6 and PB1 PB4 of unit 42 communicate with and drive the keyboard and seven segment display of the invention and peripheral pins 0 7 of unit 44 control the various elements of the optically active scale 10 Each peripheral pin may be used either as an input or an output pin the specific use being determined by the content of a corresponding bit in an I O direction regis ter contained within the unit the register contents being under the control of an operating program which 2150 controls microprocessor 40 the system s central pro cessing unit Central Processing Unit 40 is capable of performing simple arithmetic logic operations such as add sub tract logical AND OR EXCLUSIVE OR NOT and shifting Control instructions such as jump jump to subroutine return from subroutine and conditional jumps are also available The microprocessor uses a Stack to store return addresses for subroutine calls The stack is located in the RAM of MCS 6530 chips 42 and 44 The previously mentioned operating program is used to support functions of the Electronic Rule and is stored in the ROM portion of the two MCS 6530 s The pro gram can be activated by an RST reset
28. ng said sensing activat ing and displaying steps
29. nt CP must be defined The user then depresses or to move the cur sor position similar to the steps in the first phase until it is adjacent to the calibration distance He further depresses and enters the numerical value C of the calibration distance by depressing the digits in se quence It is noted that C may be negative The value of C will be displayed The user then depresses to indicate that the calibration distance is to be taken as C units At this time the calibration phase is complete and the display shows the distance C between the RP and the cursor position The third phase is the measurement phase When the user positions the cursor adjacent to the other endpoint B of the object the distance between A and B will be converted to proper units and displayed The orienta tion of the vector from A to B will also be displayed with a negative number to mean left going and a posi tive number to means right going unless a reverse orien tation has been selected by depressing F The distance setting process can also be described as 3 procedure with the first two phases identical to those of the length measuring process During the third phase the user enters a number j which may be negative by pressing the digits of j in sequence folled by The number j will be displayed and the electronic rule will move the cursor in the direction depending on the sign of j to a position such that the distance be twe
30. nt is activated by selecting the specific row and column output lines at whose intersec tion the element sits The presently preferred embodi ment contemplates the use of light emitting diodes as the scale elements but it is recognized that any elements which affect the absorbance reflectivity or emission of visible light may be used Thus while it is known to use optically passive scales for conventional measurement including scales which are inscribed for absorbing or reflecting light with greater intensity than the medium in which the scale is embedded the present invention utilized optically active scales It is contemplated that any scale comprising electronic components which can emit visible light or absorb visible light from another light source under the control of the user may be used More particularly the optically active scales contem plated herein include any scale having components wherein one or more of the following properties of light are controlled whether by electrical electromagnetic thermal or magnetic fields emission absorption reflec tion and transmission for example Such elements in clude light emitting diodes as presently selected for use in the scale liquid crystal elements etc The specific elements of the scale are selected by LSI unit 44 providing output signals on peripheral lines PAO PA7 to decoders 68 and 70 While the presently 10 5 20 40 45 50 60 65 6 preferred
31. play of the sign to the opposite ds SUBROUTINE NAME BCD FUNCTION To convert a real number whose integer portion is in SUM and fractional portion is FSUM 5 into a binary coded decimal equivalent so that it is ready for display The end product is put into D DESCRIPTION There are standard ways to perform BCD conversion SUBROUTINE NAME DIVD FUNCTION To perform binary arithmetic division The dividend and divisor are taken from DA and DB respectively The quotient is put into Q DA DB and s Q are all real numbers DESCRIPTION There are standard ways to perform division 60 38 SUBROUTINE NAME MULT FUNCTION To perform binary arithmetic multiplica tion The multiplicand and multiplier are taken from MA and MB respectively The produce is put into P MB and all real numbers DESCRIPTION There are standard ways to perform multiplication SUBROUTINE NAME ERROR FUNCTION To signal the user that a user error has been made or the capability of the device is exceeded DESCRIPTION This subroutine will not return to its calling program The routine blinks all the lights in DISPLAY The user has to depress key to reset the system and stop the blinking Having thus described the objects features and ad vantages of the present invention and having provided a preferred embodiment thereof which is to be used for illustration and not limitation it is appreciated that many variations of the
32. r com prising multiplexing means for a plurality of said control means functions of activating elements of said scale means displaying numerical representations of dis tances on said display means and responding to said input means 19 The apparatus as recited in claim 17 wherein said control means activates at least two elements to provide indices for distance delineation 15 45 50 55 65 40 20 The apparatus as recited claim 19 wherein said indices provide optically active identification of end points of a distance to be delineated 21 The apparatus as recited in claim 19 wherein said control means activates a plurality of adjacent elements to provide identification of a distance along said acti vated elements 22 The apparatus as recited in claim 13 wherein said control means comprises digital computer means 23 The apparatus as recited in claim 13 further com prising means for selecting a scale factor for displaying a numerical representation of the selected distance 24 The apparatus as recited in claim 13 further com prising means for distance measurement whereby an operator causes said control means to delineate a dis tance on said scale and said control means further pro vides a numerical representation of said distance on said display means 25 method for mesurement of distances utilizing an apparatus having an optically active scale compris ing a plurality of optically active element
33. rement unit are pro vided as inputs to the devices A series of optically active elements is spaced along a line in close proximity to the straightedge of the device to serve as a scale A keyboard permits the user to input gt numbers and to control the operations and functions 45 60 65 performed by the subject device with a digital numeric display conveying the value of a distance setting or the results of a length measurement to the user Accordingly it is a principal object of the invention to provide a distance measuring apparatus utilizing an optically active scale It is another object to provide a distance setting means having an optically active scale for use with arbitrary scale factors Yet another object is to provide computer activated distance measurement devices of a portable nature It is a further object to provide digital display for a distance measurement device activated by computer control It is still a further object to provide stored program control for a distance measurement device utilizing optically active scales Another object is to provide multiplex control signals for a computer controlled measurement device whereby keyboard scanning display and scale illumina tion signals are multiplexed Yet another object is to present a highly reliable length measuring device having high resolution thereby eliminating the need for interpolation 4 158 229 3 BRIEF DESCRIPTION OF THE DRAWINGS
34. rising a operator input menas for selecting the distance b optically active scale means having a plurality of optically active elements for delineating the se lected distance c numerical display means for displaying a numeri cal representation of the selected distance and d control means responsive to said input means for activating at least one element of said scale means and for causing said display means to display a numerical representation of a distance delineated along said scale means using the activated elements thereof whereby an operator selects a distance for display by said apparatus enters the selected distance by said input means and said control means responsive to said input means causes the selected distance to be delineated on said scale and displayed numerically on said display 14 The apparatus as recited in claim 13 wherein said scale means comprises a plurality of light emitting di odes 15 The apparatus as recited in claim 13 wherein said scale means comprises a plurality of liquid crystal ele ments 16 The apparatus as recited in claim 13 wherein said numerical display comprises a plurality of seven seg ment display elements 17 The apparatus as recited in claim 13 wherein said input means comprises a keyboard having a plurality of keys representative of plural numerical values and of plural functions for execution by said control means 18 The apparatus as recited in claim 17 furthe
35. s a numerical display an input means and a control means comprising the steps of a entering instructions to said control means on said input means for generating control signals in re sponse thereto b activating selected elements of said optically ac tive scale in response to said control means c computing a distance corresponding to the acti vated elements of said optically active scale and d displaying the computed distance on said numeri cal display 26 A method as recited in claim 25 further compris ing the steps of sensing the instructions entered on said input means and multiplexing the sensing step with the displaying and the activating steps 27 A method for distance setting on an apparatus comprising an optically active scale means having opti cally active elements therein a display means an input means and a control means comprising the steps of a entering a number representative of a selected distance to be shown on said optically active scale means via said input means b computing the appropriate optically active ele ments required for delineating the selected dis tance e activating said required optically active elements and d displaying a number on said display means corre sponding to the selected distance entered via said input means 28 method as recited in claim 27 further compris ing the steps of sensing the selected distance entered via said input means and multiplexi
36. ssed the control will set up a nonzero value in the accumulator A Otherwise A will be cleared to Zero The routine calling SCAN can check the contents of A to determine if a key is depressed 4 CONV This routine uses an internal table to convert a number into bit patterns which correctly select the segments of one seven segment display unit causing the number to be displayed in the selected unit 5 LED This routine outputs a value to MCS 6530 unit 44 peripheral pins causing one of the LED s in the scale to turn on 6 KEY ONEROW These routines read the key board to determine which key is depressed ONEROW checks only one row of the keys KEY calls ONEROW repeatedly to check every row 7 DIVD A division routine 8 MULT A multiplication routine 5 e uA 30 40 wa 0 55 6 65 10 9 BCD This routine converts a binary number to its binary coded decimal BCD equivalent which will then be used to drive the seven segment display 10 ERROR This routine blinks all the lights in the seven segment LED s to signal an error The routine is activated only when illegal operations are detected or when an operation exceeds the precision or margins of the electronic rule When the power is initially turned on and the is depressed by the user an RST interrupt takes place which starts the SCAN sequence The SCAN routine will drive the display and the scale and monitor the keyboar
37. ted During each such activation pins 0 6 now caused to act as input pins are sequentially se lected thus scanning each key in the selected row of the keyboard If a key depression is detected the operating program executes the function represented thereby If not the next row is scanned After execution of the function or determining that no key was depressed the program again energizes the display and scale The functioning of the main operating program is more clearly shown in Appendix A which includes a flow chart representation thereof The various subrou tines are shown in Appendix B As is apparent from the preceeding description the inventive device thus in cludes a means for multiplexing the display and key board sensing thereby providing for the use of fewer pins lines connections and other hardware In view of the high operating speeds available in digital computers such multiplexing does not adversely affect the user s perception of the display and scale Specifically objec tionable flicker and other disadvantages do not result from the approach used herein Referring now to FIG 4 scale 10 is shown compris ing a plurality of active optical elements disposed at intersections of addressing lines for the elements ema nating from decoders 68 and 70 The decoders are avail able for example under the label SN 74154 from Texas Instruments and comprise four to sixteen decoders A particular optical eleme
38. to the left of RP 5 When the user is defining his own measurement unit using CP key the sign of the unit depends on the relative positions of RP and X and whether the minus key is depressed or not The following cases are possible X is the cursor position Minus key Relative positions of X RP depressed New sign convention X to the right of RP YES reverse UNITSIGN 1 X to the right of RP NO default X to the left of RP YES default X to the left of RP NO reverse UNITSIGN 1 EXPLANATION OF MAIN There are three JSR SCAN statements in the main program MAIN If the power is just turned and no key is depressed the control stays in the loop of the second JSR SCAN starting with Repeat When a key is depressed the control enters into the third JSR SCAN which double checks if the key is indeed de pressed not noise If so go to EXEC Otherwise the 13 control returns to the second JSR SCAN After EXEC depressed the control returns to the loop of the first 4 158 229 14 JSR SCAN starting with Start and waits until key is which performs the function associated with the key A released PROGRAM NAME MAIN FUNCTION This is the main body of the operating program RS key is depressed Power on Lb MAIN JSR INIT Start JSR SCAN Repeat JSR SCAN FUNCTION To perform the specific operations as defined for the function keys of the KEYBOARD Exec JSR KEY l Yes 16
39. uch a speed that the multiplex ing is not discernible operating program consists of a main program and several subroutines The main program and the major subroutines are described briefly here 1 MAIN This program can be entered as a result of an RST interrupt Upon entering the program data variables will be initialized by calling subroutine INIT SCAN will then be called to execute the scan cycle i e to display the scale LED to activate the numerical display and to read the keyboard in a multiplexed man ner When a key in the keyboard is depressed by the user the program will also branch to a segment of code labeled EXEC in which the function associated with the key is executed If no key is depressed the program will repeat the scan cycle 2 INIT INIT1 This is the initialization routine which sets up the initial values of all variables used in the operating program and moves RP to the left margin of the scale is a different entry point to the subroutine 3 SCAN The routine first selects each of the six seven segment units in sequence to display a number with possibly a sign and a unit then turns on the two LED lights in the scale that correspond to RP and X cursor and checks to see if any key in the keyboard is depressed If no key is depressed the same control se quence is repeated that is displaying a number turning on RP and X and checking the keyboard If a key is found depre
40. x MS hy ee M n 4 70 6 E B gt Fo A MICE 42 1 152222 44154 ES gt D NE NE BRE a zs m CN 8 3 ATAPI 23 27 4 6 s VEC U S Patent Jun 12 1979 Sheet 5 of 5 Vec RI 40 4 158 229 72 4 5 MER I9 0556 R4 4 158 229 1 ELECTRONIC RULE FOR PRECISE DISTANCE MEASUREMENT AND DISTANCE SETTING BACKGROUND OF THE INVENTION 1 Field of the Invention The invention relates to distance measurement and determination devices and more particularly to elec tronically controlled digital display of distances deter mined with the aid of an optically active scale under the control of keyboard instructions 2 Description of the Prior Art As is well known to those versed in the art of per forming measurements of lengths and distances ranging from the order of tenths of millimeters to several feet a great variety of instruments with various degrees of precision is available In the order of increasing preci sion there are the meter stick or foot ruler the vernier caliper the micrometer and acoustical and electromag netic wave devices using the principle of wave reflec tion or used as interferometers For ordinary measure ments of lengths
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