CA1110346A - Means for adjustment of speed of prime mover - Google Patents

Abstract

Abstract of the Disclosure A microprocessor is programmed to generate reference envelopes of a specified time duration and synchronized with clock pulses, and circuit means is associated with such microprocessor for indicating desired speed of a prime mover through comparison of prime mover actual speed with said reference envelope, and means is provided for adjusting prime mover speed to correspond with such reference envelope.

Description

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B k~ound of the Inveneion In high speed operation of rotating parts, lt is necessary to maintain such parts at a rate of rotation which pr~vides for reliable and efflcient results in accordan~e with predetermined levels. In the field of printing, or example, when the printing is acc~mpllshed by means of i~pact mechani~m striking a character bearing member of the rotating type~ such member must be rapidly moved into posl~ion for each and every character thereon to be struck by the lmpact mechanism. The character bearing member may9 for example, be in ~he form of a drum or typewheel which is driven by a mo~or, the speed of such motor being maintained to make certain that the drum or type-wheel i8 in ~he proper posltion at ehe instant that the impace mech~nism is dr'.ven agalnst the selected character thereon for printing of such character. It is, therefore~ necessary that ~, the speed oi the motor driver for the character bearing member be ad~usted so that such member cAn be positioned suficiently fast to avoid printing a character too late in the cycle, while . at the ~ame time ~eeing that the motor 18 not driven faster than its rated speèd. Of cour~e~ the mo~or speed control system should include provision for ad~u~t~ng the spe d of the motor so as to obtain a ~peclfied number of bearing member character positions in a predetermined time to meet the require~
ments of the operation.
A number of ways and means for controlllng motor speeds have lncluded both simple and complex system~. Repre~

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sentative of control systems in the prior ar~ is Uni~ed States Patent No. 2,706,270, issued on April 129 1955 ~o F, G. S~eele9 which dlscloses a digital control system including a palr of -~
pul3e carrying channels for controlling ~he setting of a pair o reversing switches connected to rotate the armature of a motor~ on the occurrence of each clock pulse, in the direction dictated by the informstion. Vnited Stat~s Patent No. 3,237,17 issued on February 22, 1966 to A.G. Valentine, discloses control appar~tus for a closed loop system having a phase detector, a reversible counter, flip-flop means or computer means, and a digital to analog converter or voltage switch means. Indicating means in the form of a voltmeter is connected to receive an analog output signal from the voltage switch means. Unlted States Patent No. 39586,953, issued on June 22, 1971 to C. O.
Markkanen et al., shows a stepper motor control system includ-ing an encoder which develops a coded signal representative of a plurality of sh~aft positions on either side o~ a reference position. Coded s ign~ls representative of ~he desired position of~the motor and shaft poSitiDn signals are applied to a com-parator and logic circuit which develops output pulses to bringthe coded signals and the position signals into coincidence.
~` Another United States Paten~ No. 3,648,141, issued on March 7, 1972 to D. W, Scheer, shows a tape drive error-canceling system having a speed control circuit using comparator means for c~m- -paring a capstan speed responsive varlable frequency signal with a reference frequency proportional to a desired capstan .. .

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speed. A memory stores a separ~te speed correction signal for each of the capstan angular positlons. The memory information is read concurrently with a sensing of each position and applied -~with the outpu~ signal from the comparator means to motor energizing means to control the capstan speed. United States Patent No. 3,659,524, issued on May ~9 1972 to J. Beery et al., shows a printer control system including first drive means operated at one speed and second drive means operated at a slower speed~ with means for detecting the presence of a docu ment. The control means also synchronize~ the operation of the prin~ hammer, the print wheel and document movement responsive to speed of the document. And, Unit:ed States Patent No.
3,838,258, issued on September 24, 1974 to D. J~ Logan, dis-closes a control system for a step motor which includes a computer to control the energization of the motor in response to information supplied thereto. Motor increments are produced by~the computer program without the aid of an external clock or feedback signals from the motor. The computer program includes one wait loop following each change in the output word to pro- ~;
vide a predetermined delay preceding the nex~ word change ~nd to control the motor velocity.
Summary of the Inventlon ~, The present invention xelates to method and apparstus for ad~usting the speed o~ a prime mover in the nature of a stepping motor and more particularly to the providing of a control system which utilizes a microprocessor : .. .. " . , having clock pulse and processor memory capability for gener-ating timing signals designated as reference and speed en velopes. In accordance with the present invention, there is ~ ;
provided a method of controlling the speed of a prime mover comprising the steps of generating a programmed re-ference signal of predetermined time duration, generating a speed signal indicative of the actual speed of the prime mover in successive relationship with said reference signal, repeating `~
said reference signal in duplicating manner for a desired number of times, repeating said speed signal in alternate -relationship with said reference signal for said number of times, utilizing programmed memory for tracking the number of repeated speed signals and reference signals, synchronizing said reference signals and said speed signals by clocking predetermined time periods therewith, setting the programmed memory to indic~te mode index of the prime mover, observing diferences in time periods between said reference signals and said speed signals, and adjusting the width of said speed signals to equal the width of said reference signals.
Additionally, the present invention provides a control system for adjusting the speed of a prime mover to conform with predetermined parameters, including means for generating ~.
reference signals of fixed time duration, memory means asso-ciated with said reference signal generating means for reading the number of cycles of fixed time duration of said reference :;
signals, means for generating signals indicative of the speed of said prime mover in alternate relationship with said reference signals, means indicating differences in time duration between said reference signals and said speed sig-nals, and means for adjusting the width of said speed signals to correspond with the width of said reference signals. Upon ., .,. .. - .; . .

~ /;39!~6 starting rotation by the first phase switching of the prime mover, a one-shot multivibrator, hereinafter referred to as speed one-shot and associated with the prime mover, is trigger-ed so as to generate two pulses for each character step of rotation of the character bearing member, with subsequent phase :~
switchings of the prime mover occurring on the falling edge of each of the speed one~shot pulses, with the resultant obser-vation that the width of such speed one-shot pulses affects the times of phase switching and the speed of rotation of the motor~ Tbe leading edge of a particular speed one-shot pulse triggers a further one-shot multivibrator, hereinafter referred to as delay one-shot and associated with the micro-processor, and the final phase switc.hing of such prime mover occurs on the falling edge of this further one-shot pulse.
A first signal or speed envelope in the nature of a voltage pulse is produced at a test point wit:h such signal beginning ~:
at the first phase switching of the prime mover and ending at the triggering of the delay one-shot~
For a seven character sequence of stepping motion, the width of the first signal or speed envelope is a predeter-mined duration of time, and means for adjusting the speed one~
shot is desirable for achieving the correct relationship of pulsewidth-time duration. At regular intervals of repeated seven character sequence cycles, an indicating means in the -5a- :-~,"

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nature of a moving needle meter is connected for indlcating a voltage reading which is proportional to the width of the speed envelope, ~uring alternate time int~rvals of approximate- ~ :
ly one second, the stepping motor is mo~ed through the seven character sequence twenty times, with each ~even character stepping sequence being ~ynchronized with ~ transport clock havlng a nominal period of time sufficlently long to allow the meter to settle to an average voltage indication. During the opposing one second alternate time in~ervals, a second signal or reference envelope is generated by the microprocessor through programmed delays at the speed envelope test point of a determined time duration in width and is also synchr~nized with the transport clock at the rate of twenty times ln approximately one second. These alternate time interval happenin~s are continued as long AS necessary for adJusting ehe speed one-shot and observing a steady position of the meter -- which steady position indlcates that the width of the speed enyelope is equal to the width of the reference ~:
:: en~elope as any percentage difference in the width of the two ~velopes is directly proportional to the difference ln voltage readings.
In view of the above d1scussion, the princ~pal ob~ect ;~ of the present invention is to provide a slmplifled method ~or ad~usting the speed of a prime mover.
Another ob~ect of the present invention i~ to provide a method utilizing present circuitry in apparatus whlch requires : ~ -~ Q~346 speed ad~ustment of a prime mover .
An additional object of the present ~nvention is to provide means for indicating the relative speed of a prime mover.
A further ob~ect of the present i~ventlon is to provide reference and speed envelopes at a test point for observing indication of need for adjustment in speed of a prime mover.
Additional advantages and features of the presant lnvention will become apparent and fully understood from a !~
reading of the following description taken together wlth the annexed drawlng, ln whlch:
Flg. 1 is a side elevational view of encoding mechan-ism employing a stepping motor and with which the presen~
invention i~ assoeiated;
Fig. 2 is a diagrammatlc view of the ma~or components of the stepping motor speed ad~usting system; .~:
Fig. 3 is a timing chart of the pulsing signals of the system;
Fig. 4 ~s a dlagram showlng the sequence and time dur~tion of speed and reference signals of the control system;
Flg. 5 is a flow diagram of the implementation of the speed ad~ustment of the steppin~ motor;
Fig. 6 is a block diagram of the speed ~d~ustment syRtem for a modlfied form of the invention~ -Fig. 7 is a tim~ng chart of the pulsing signals o~

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the modification shown in Fig. 6;
Fig. 8 is a flow diagram of the implementation of the speed ad~ustment of the lnvention modiflcation shGwn in Fig. 6;
Fig. 9, on the sheet with Figs. 6 and 7, ls a block diagram of the speed ad~ustment system of a further modified orm of the inventlon; and Fig. 10, on the sheet with Fig. 8, is a timing chart showing the relationship of th~ speed and ~he reference envelopes to ~he clock pul~e.
The encGding mechanism of the preferred embodiment of the instant invent~on basically includes a typewheel, a stepping : motor for driving and controlling the! rotation and position of the typewheel, and an electromagnetically operated h~mmer, the impact of which can be controlled by potentiometers to regulate hammer force to suit specific characters on the typewheel. Fig.
: 1 show3, in a side elevational viewt the important parts o~ such ~n encoding mechanism as supported from a m~unting plate 10 which may be one side frame member of a business machine. A typewheel 12 with type characters 14 on the periphery thereof is driven and controlled in incre~ental manner by a stepping motor 16~
and an aligner mechanism 18 is positioned adjacent the motor 1~.
The aligner mechanism 18 is provided with well-known al~gning bar, etc. engageable with the typewheel 12 for holding the type-wheel in precise position during the printing operation. A
ribbon 30 i5 caused to be driven in a path above the typewheel and a check or like document 3~ may be placed or positloned above 3~

the ribbon 30 to be contacted by the impact face 34 of a hamm~r 36 carried on a pivot 38 of a hæmmer frame 40. A hammer core 42 and a hammer coil 44 are carried on the frame 40 to operate the hammer 36 against the return force of a spring 46. A timing disc 48 having a plurality of slots or aper~ures 50 along the circumference thereof is rotatably supported ad~acent the hammer 36 and the ~ypewheel 12, and is operably connected with the motor 16. While the showing and the description of the encoding mechanism are limited in scope, the various parts and the opera~
tion of these parts are generally well-kn~n in the encodlng of documents.
~ In F~g. 2 is shown a block diagram of the ma~or camponents of the speed ad~usting system for the stepplng motor 16, wherein a controller board 60 includes a microprocessor 62, one type o which may be the MCS-4" as manufactured by Intel Corporation~ associated with a memory 64 having instructions ~.
stored ~herein in any well-known manner for implementing the invention, a clock 66 for providing pulses of a predetermined rate to the microprocessor 62, and an input/output device 68 ; 20 associated with the microprocessor 62 and the control circults distal ~rom the board ~0. The memory 64 includes read only and ~;
random access (ROM and R~M) capability, and the microprocessor has a counter for tracking the number of envelopes or repeats o namlnal one second t~me periods. A delay one shot 69, of thP
monostable multivibrator type, ls triggered by the microprocessor at programmed intervals and the microprocessor also receiveæ

3~L6 return signalx from the one-shot when the delay is completed.
The dri~er hardware 70 for the motor 16 is connected to the I/0 device 68 for recelving pulses therefrom for driving the motor 16. A speed one-shot 72y of the monostable multivibrator type, receives trigger pulsing signals from the motor 16 via timing d~sc 48 operated thereby and sends signals to the I/0 device 68, the one-shot 72 having an ad~ustable device 74, in the form of a potentiometer, for adjusting the width of the pulse or signal ~:
t~ the I/O device 6~. The motor driver hardware 70 ~nd the 10 speed one-shot 72 comprise a portion of driver board adjacent the controller board. An exterlor connection from the I/O
module 68 also lncludes a signal path to a test point 76 to whlch is connected a moving needle voltmeter 78, such voltmeter being connected to a point 80 at ground potential.
A timing'ohart is shawn in Fig. 3 wherein the timing relationship or "n" number of char~cter steps o the stepping motor 16 i9 indicated only for a number of phase switching t~mes. The fir~t phase switching shown as 90 causes the motor 16 to begin rotating frum a rest condition with speed one-shot 20 72 pulses 92 (two for each character step) being triggered by the rotation of the motor and sensed by the microprocessor 62.
For a seven character step of the motor 16, a total of fourteen such pulses 92 are triggered and are read by the microprocessor 62. Subsequent phase switchings (except for the final switch-ing) occur on the falling edge of the speed one-shot pulses. It is thus seen that the width of the speed one-shot pulses affect .. ..

the times of phase switching and the speed of rot~tion of the motor 16. As the pulsewldth 92 of the one-s~ots decreases, the phase switchings 90 are compressed in time and the motor stepping speed is increased~ whereas an increase in the width of the one-shot pulses extends the time of phase switchings and the motor stepping speed i8 decreased. In accordanee with derived para-meters, there are 2 n phase switchings and 2 n speed one-sho~
pulses for n character steps. As illustrated in Fig. 3 9 the leading edge of the 2 n-l speed one shot pulse 94 triggers a :~
delay one-sho~: pulse 96, and the final phase switching occurs on the falling edge of this pulse.
: A speed signal or speed e~velope 98 of certain dura-tion ls produced at the test point 76, such signal beglnning at the time of first phase switching and ending at the triggering of the delay one-shot pulse 96 (Fig. 3). The triggering of the delay one-shot pulse 96 determines the time period or width of the speed envelope 98. For a given .qequence covering seven character~9 the wldth of the speed envelope pulse 98 is 23.5 ~` milliseconds, such pulse width being achieved and maintained by ad~usting ~he potentiometer 74 o the speed one-shot 72. If this pulse width or speed enve~ope g8 is repeated at regular intervals, the meter 78 (with a sufficiently long time constant), connected between the test point 76 and ground 80; will indicate a voltage whlch is proportional to the width of the speed envelope 98. The voltage pulses of 0-5 volts produced at the . test point 76 are read by the meter 78 as an average of the ~ 6 amplltudes of such voltages.
Durlng alternate time interv~ls of approximately one ~econd, i.e., period equal to 20 times nominal 50 milliseconds clock pulse, the stepping motor 16 is caused to be moved 20 times through the seven character s~eps (speed envelope), with the start of each seven character stepping sequence being synchronized wi~h the transport clock 66 whlch has, as des~gnat-ed above~ the nominal pulse period of 50 milliseconds and which pulse period is of suffieient length to allow the meter 78 to settle to an average voltage indication. Durlng the opposing one second alternate timP intervals, the microprocessor 62 ~:~
generates, through programmed delay~ i.e., those delays which are inherent within the instruction cycle times, a fixed reference signal or envelope of 23.5 mllliseconds in width at the speed envelope test point 7Sy such reference envelope being also synchronized with the transport clock 66.and generated 20 ~imes during such one second period. The test point 76 ser~es as a common access port for both the sp2ed and reference signal~, AS seen in Fig. 4, whlch shows the sequence of speed and reference signals or envelopes appeArlng at the test point 76, the sequence is continued as long as required for completing speed ad~ustment in accordance with the instant invention. The sequence in Fig. 4 shows a series o such one second time per~ods of alternate speed and reference en~elopes in relation to the 20 time cy~les of the transport clock 66. With the generation of such speed and reference signals at point 76, tha 39L~

speed one-sho~ 72 may~ if required~ be then adjusted through the pulse width adjusting device 74 until the meter 78 needle remains steady which indicates that the wid~h of thP speed envelope ls equal to the wld~h of the reference envelope.
In analy~ing the relationship of the length of pulse widths of ~he speed envelope and the reference envelope 9 it iq seen that as the motor 16 is ro~ated the average voltage of the - speed envelope 98 at the test point 76 i8 given by VS ~ T~ X Vref : 10 where Ts ~ width of speed envelope Tx ~ period of transport clock Vref - "ON" voltage! of speed envelope Similarly, the average voltage of the reference envelope at test po~nt 76 is given t)y Vr ~ T x Vref wher~
Tr ~ w~dth of reference envelope The ratio of thes~ two voltage~ is glven by ratio Vr Tr wherein it iS seen that the voltage ratio is independent of both Vref (the "ON" vol~age of the speed envelope) and the speed of the transport clock assuming that any perturbations in the period of the transport clock average out to zero.
The swlng of the needle on the meter 78 can ~180 be used to indicate the relative width of the ~peed and reference envelopes and whether the motor is running fast or slow. In ~-this regard Let T~ ~ Tr + ~ x Tr where ~ ~ Ts - T~

~ that is, percent error ~ ~ x 100%
; the voltage ratio is given by , ~rratio ~ TS ~ lr ~ ~ X Tr It is thus seen that the percPntage difference in the respective widths of the speed and reference envelopes is directly proportional to the difference in the voltage readings~
Stepp~ng motor flnd speed ad~ustments in an encoding mechanism generally have required in the past that a precise time base generator be used to initla~e the seven character steps repetitively at fixed intervals. The output of the speed envelope is applied to a test point, however this voltage is referenced to another test point having a voltage equal ~o the average voltage ofithe sp ed envelope. A meter connected be-tween these test points will then indicate zero volts at the correct speed a~ustment.
~` Contrariwlse, the apparatus and method of the pres~nt invention has eliminated the heretofore known drawbacks~ viz.
the meter must be ~ccurately calibrated to indicate zero volts correctly, that the voltage at the reference test point must be precise, and that a precise time base was needed. Additionally~
procedures have been simplified in that the test probe need not be moved from one test point to another since the reference and speed envelopes of the present invention are applied at the same ., . ~

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test point as used in the symmetry test for the motor, which symme~ry test requires adjustment only for a steady needle on the indicatlng device or meter.
In Fig. 5 is shown a fl~w diagram of the implementa^
tion of the speed ad~ustment on the encoding mechanism applica-tion of the present invention wherein the program sets forth and completes a series of steps by the microprocessor 62 for controlling the speed of the stepping motor 16 in positioning the typewheel 12. The first steps cover the ~etting of or initiating the control count for twenty repeats of the seven character sequence along with setting of a mode index of the microprocessor to 7ero and synchronizing of negative and posi-tive voltages of the transport clock 66. The mode index is used to ascertain whether to output the speed envelope or reference envelope to the test point 76. A twelve millisecond delay is genera~ed to reflect the timing of motor positioning in nonmal operation after whlch it is determined whether or not the twenty repeats have been completed. If such twenty repeats are completed and the mode of the motor output is zero9 the mode ~-index is complemented to change the mode from the motor output to the reference output. The counter or regis~er associated with the microprocessor 62 counts up by one on generation of the speed envelope 98, and likewise counts up by one on generation of the reference envelope, the generation of such speed and reference envelopes being under control of the micropxocessor.
If the speed test mode index equals zero, the test output is ;~

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)3~6 turned on ~ust ~efore the first phase switching of the motor ; 16, the motor is moved clockwise ~hrough the seven character steps, and then the test output is turned off just prior to ~; the "next-to-last" phase swltching. If the mode index does not equal zero after complementing from motor to reference output, the test output signal is turned on and a 24 millisecond delay is generated to the reference output. In elther case~ a repeat operation counter (Fig. 5) is incremented and another cycle is then begun. Implementation of the speed ad~us~ment of the motor 16 may include an alternate step to that of incrementing the counter near the end of the program~ such alternate s~ep giving an indication whether the diagnostics switch is on or off. If this switch is still on, another cycle is set and com-pleted. If this switch is off, the test is completed.
A modified form of the present inventive concept is shown in Figs. 63 7, and 8 for ad~ustment of the idllng speed of an automobile engine 120 (Fig, 6~ wherein a voltmeter 122 s connected between the test point P of a test set 124, which test set is connected by a spark plug lead 130 to the engine 120. The voltmeter 122 is connected to ground 126 and an idle ad~usting device 128 (spark control~ fuel-air mixture control, etc.) is used to set the idle engine speed. Fig. 7 shows a timing diagram of slgnals or pulses ln the idle ad~u~tment of :
the engine 120, with the engine being exemplified as running fast or above the correct idle speed Basically, the speed of the engine 120 ls a function of the rate of firing of the spark . " ~ :

plugs employed, the ~iming diagram of Fig. 7 showing only the successive firings of one plug. For each pulse 132 of a flxed number of firings N of the spark plug, a microprocessor in the test set 124 detects the firing and outputs a pulse 134 of known width Tl, which pulse is output to test point P. The time between the ccmpletion of one pulse and the start of the next pulse (shown as T2V) is variable and is a funol~n of the engine speed. After completion of the above N firings, the microprocessor for N repeat cycles outputs to ~est point P a ~ 10 pulse 136 of width T~ followed by no pulse for a fixed time T2r which time T2r is chosen to be equal to the width T2V when the engine is adjusted to the desired idle speed. At the com- -~
pletion of N cycles of generated reference pulses 136 at the test point P, the firing cycle is repeated until the engine speed ad~ustment is completed. The moving needle voltmeter 122 connected between test point P and ground 126 will indicate a -~ steady needle position when the engine idle speed is correctly :: .
ad~usted to the desired value. The number of cycles N of gen-erated reference pulses at test point P must be suff~len~ to ~'~
allow the meter 122 to reach a steady state condition.
In F~g. 8 is shown a f low chart of the implementation of the engine speed ad~ustment. Starting at I ~counter set) - equal to zero, the output pulse 134 of width Tl is caused to appear at test point P when the spark plug fires. This indica-tion results in 1 3 I ~ l. The next step detenmines whether or not I ~ N. If not, the above sequence is repeated until I - N.

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~ 3~ 6 When I - N, I is then set to zero. An output pulse 136 of wldth Tl is caused to be output to test point P, followed by a delay of tlme T2r durlng which no signal i8 output to test point P. This results in I = I ~ 1. The next step determines whether or no~ I a N. If not, the sequence is repeated until I - N~ When I = N, the sequence associated with the spark plug firing is repeated. The above cycle continues until the meter 122 connected to test point P indicates a steady reading, thereby indicating correct ad~ustment of the engine idling speed.
A further form of the inventive concept is shown in Fig. 9 wherein an inductlon motor lS0 drives a turn~able 152.
A sensor 154 senses the speed of rotation of the turntable and is connected to a test set 156, A speed ad~usting de~ice 158 is connected to the motor 150, which device may, for example, be in the form of a potentiometer to effect speed ad~ustment to the motor, as determined by the needle of a voltmeter 160 connected between a te~t point P of the test set 156 and a ground 162. Again the test set includes a microproce~ssor with associated apparatus and circuitry to program the various steps of implementing the adjustment procedure. It is to be noted that while a microprocessor is well-adapted to provide the processing logic of such various steps, hardwired logic could also be used in the invention~
To further aid in understanding the timing of the respective pulses or signals, Fig. 10 shGws a timing chart of the relationship between the continuous cycle of clock pulses ~ 3 and the speed and reference envelopes, which chart relates one test condition of times of pr~determined and actual operational signals. As mentioned earller, the clock pulse has a nominal period of 50 milliseconds, designated as pulse 170, such pulse period being constant during the entire time of operation of the adjusting procedure. Likewise, the reference envelope has a predetermined time of 23.5 milliseconds for the first portion 172 of its cycle~ such time periods also being constant during the entire time of operation. Regarding the speed envelope (i.e. the moving of the stepping motor 16 through the seven character steps), it is assumed that the speed of such motor requires an ad~ustment thereof to properly posltion the type characters 14 for printing. While an initial time period or pulse may be of shorter or longer duration, for purposes of the present description, a first portion 176 o the speed envelope is shcwn in Fig. 10 as being lS.5 milliseconds with the latter portion then being 34.5 milliseconds. It is of course readily noted that the first portion of the speed envelope may have an initial time per~od longer than 23.5 milliseconds and that the `;~
20 ad3ustment would be needed to correct back to the 23.5 milli- ;
second period Also9 while a plurality of like speed envelopes :~will foll~w initially until the required ad~ustment operation is commenced, for purposes of illustration a first portion 180 of a second speed envelope is shown in Fig. 10 as 16.5 milli-seconds with the second portion 182 of such envelope being 33.5 milliseconds. Further, the first portion 184 of a third speed .. , ~ . . ... . .

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envelope ls 17,5 milliseconds with the latter portion of such envelope being 32,5 milliseconds, After the number of like speed envelopes have been lnitially seen at the test point 76, through ad~ustment of the potentiometer 74 the above representa-tive speed envelope changes occur until the first portion 186 of a succeeding speed envelope has a time of 23.5 milliseconds which is the desired time for the speed envelope as compared to the reference envelope. The above pul~e width adjustment of the speed envelope ls performed during a period of time by observing the position of the needle of the voltmeter 78 while ad~usting the potentiometer 74 to produce a speed envelope of 23.5 milliseconds comparable to the 23.5 millisecond period of the reference envelope.
It is thus se~n that herein shown and described ls apparatus and method for adjustlng thle speed of a prime mover wherein logic is provided by a microprocessor in a manner which utilizes alternate signals in clrcuitry along with means for indicating when the prime mover is or is not running at the desired speed. The desired speed of such prime mover is attained when the width of the speed envelope equals the width of the reierence envelope. The apparatus and method compri6es a con-~rol system whlch enables the accomplishments of the o~jects and advantages mentioned above, and while several embodiments ~ -have been disclosed herein9 variations thereof may occur to those skilled in the art. It is contemplated that all such var-iations not departing from the spirit and scope of the invention hereof are to be construed in accordance with the followingclaims.

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Claims (23)

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:

1. A method of controlling the speed of a prime mover comprising the steps of generating a programmed refer-ence signal of predetermined time duration, generating a speed signal indicative of the actual speed of the prime mover in successive relationship with said reference signal, repeating said reference signal in duplicating manner for a desired number of times, repeating said speed signal in alternate relationship with said reference signal for said number of times, utilizing programmed memory for tracking the number of repeated speed signals and reference signals, synchronizing said reference signals and said speed signals by clocking predetermined time periods therewith, setting the programmed memory to indicate mode index of the prime mover, observing differences in time periods between said reference signals and said speed signals, and adjusting the width of said speed signals to equal the width of said reference signals.

2. The method of claim 1 including the additional step of generating a delay signal after initiation of the generation of each speed signal for determining the time duration of each of said speed signals.
3. A control system for adjusting the speed of a prime mover to conform with predetermined parameters, in-cluding means for generating reference signals of fixed time duration, memory means associated with said reference signal generating means for reading the number of cycles of fixed time duration of said reference signals r means for gener-

3. (concluded) ating signals indicative of the speed of said prime mover in alternate relationship with said reference signals, means indicating differences in time duration between said refer-ence signals and said speed signals, and means for adjusting the width of said speed signals to correspond with the width of said reference signals.

4. The system of claim 3 including delay means associated with said reference signal generating means for determining the time duration of said speed signals.

5. The system of claim 3 including clock means for synchronizing said reference signals and said speed signals.

6. The system of claim 3 wherein said reference signal generating means comprises a microprocessor programmed to repeat cycles of reference signals to said indicating means.

7. The system of claim 3 wherein said speed signal generating means comprises a one-shot multivibrator associated with said prime mover for generating alternate speed signals.

8. The system of claim 3 wherein said indicating means comprises a voltage responsive device for indicating a voltage differential proportional to the pulse width of said reference signals and to the pulse width of said speed signals.

9. The system of claim 3 wherein said adjusting means comprises a potentiometer device associated with said speed signal generating means.

10. The system of claim 3 wherein said prime mover is a stepping motor.

11. The system of claim 3 wherein said prime mover is an induction motor.

12. The system of claim 3 wherein said prime mover is an internal combustion engine.

13. The system of claim 7 wherein said adjusting means comprises a potentiometer device associated with said one-shot multivibrator permitting adjustment of the width of said speed signals generated thereby.

14. In a printer having a rotatable type character carrying member, drive means for rotating said member, hammer means for impacting against the type characters, and means for adjusting the speed of rotation of said drive means to be com-patible with the impacting of said hammer means comprising processor means for generating reference pulses of fixed time duration, trigger means associated with said drive means for generating pulses indicative of the speed of rotation of said drive means, said speed pulses occurring in alternate rela-tionship with said reference pulses, memory means associated with said processor means for reading a number of cycles of alternate reference pulses and speed pulses, means connected

14. (concluded) with said processor means and with said trigger means for indicating difference in pulse width between said reference pulses and said speed pulses, and means connected with said trigger means for adjusting the width of said speed pulses to correspond with the width of said reference pulses.

15. In the printer of claim 14 including delay means associated with said processor means for determining the time duration of said speed pulses.

16. In the printer of claim 14 including clock means for synchronizing said reference pulses and said speed pulses at the time of initiation of each respective pulse.

17. In the printer of claim 14 including common port means associated with said processor means and with said indicating means for accessing of said reference pulses and of said speed pulses.

18. In the printer of claim 14 wherein said proces-sor means comprises a microprocessor programmed to repeat cycles of reference pulses to said indicating means.

19. In the printer of claim 14 wherein said trigger means comprises a one-shot multivibrator for generating alternate speed pulses.

20. In the printer of claim 14 wherein said indi-cating means comprises a voltage responsive device for indi-cating a voltage differential proportional to the width of said reference pulses in relation to the width of said speed pulses.

21. In the printer of claim 14 wherein said adjusting means comprises a potentiometer device associated with said trigger means.

22. In the printer of claim 14 wherein said drive means comprises a stepping motor for incrementally rotating said type character carrying member.

23. In the printer of claim 19 wherein said adjust-ing means comprises a potentiometer device associated with said one-shot multivibrator permitting adjustment of the width of said speed pulses generated thereby.