CA1187546A - Time responsive variable voltage power supply - Google Patents
Time responsive variable voltage power supplyInfo
- Publication number
- CA1187546A CA1187546A CA000380105A CA380105A CA1187546A CA 1187546 A CA1187546 A CA 1187546A CA 000380105 A CA000380105 A CA 000380105A CA 380105 A CA380105 A CA 380105A CA 1187546 A CA1187546 A CA 1187546A
- Authority
- CA
- Canada
- Prior art keywords
- output
- input
- voltage
- power supply
- counter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
Landscapes
- Control Of Electrical Variables (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A variable voltage power supply includes a switching device through which line AC current is passed in response to the time during which a level setting voltage is applied to a control circuit for the switching device. During the duration of the level setting signal, periodic electrical signals are applied to a counter which is cyclicly incremented and decremented between predetermined lower and upper count limits until the level setting signal is terminated. The count is used as a measure of time into each half cycle of the line AC voltage at which the switch device is closed, the switch device being opened in response to the zero voltage crossing at the end of each half cycle of the AC voltage.
A variable voltage power supply includes a switching device through which line AC current is passed in response to the time during which a level setting voltage is applied to a control circuit for the switching device. During the duration of the level setting signal, periodic electrical signals are applied to a counter which is cyclicly incremented and decremented between predetermined lower and upper count limits until the level setting signal is terminated. The count is used as a measure of time into each half cycle of the line AC voltage at which the switch device is closed, the switch device being opened in response to the zero voltage crossing at the end of each half cycle of the AC voltage.
Description
B~CKGi~O~ O~ lE INVE~TION
___ __ ______ _ The instant invention pertains to the art of variable voltage ~C power supply having an input at which an AC voltage is applied and an output at which a voltage of variable magnitude can be used to power an applian oe. The type of variable voltage p~wer supply with which the invention deals applies particularly to devices used for dimming incandescent lights in a plant or residence.
Various types of devices for dimming lights are kncwn to the art including variable transfoxmers, rheostats and those employing high-speed switchiny devices such as silicon-controlled rectifiers and triacs.
In prior art devices employing high-speed switching devices to disconnect the line voltage from the appliance during portions of the alternating voltage cycle, a control must normally be turned or otherwise moved to a position consistent with the turn-on point of the switching device in the AC cycle. Although useful for some applicatio~s, these devices have shortcom m gs which render them difficult to-use in others.
For example, if the level of light is to be controlled from a remote location, radio controlled servo-motors must be used to position the control.
Prior art devices also do not lend themselves -to use with touch-actuated controls which can provide a constant voltage signal during the duration of a pressure, temperature or body capacitance applied to the surface of the controls. Such controls, in addition to their utility, are aesthetically pleasing particularly when used in mcdern decors.
SU~ RY OF T~E ~ rIO~
~5 m e instant invention teaches in accordance with one aspect thereof the construction and use of a variable voltage power supply having an input adapted to be connected to an alternating voltage and an output, a latching switch means having one terminal connected to the input and another termunal connected to the output and a control terminal to which a control voltage is applied for latching the switch in a closed condition tjJ~S~
at a preset time ~l a sub-cycle of the line-alternating voltage. The switch means chanyes to an open state from a closed state to interrupt current flow to the output of the power supply during the zero crossing which tenmnates the alternating voltage sub,cycle. The control circuit includes a source of periodic signals and a counter to which signals are applied for incrementing and then decrementing the count in the counter between lower and upper counting limits in response to application of a level-setting constant voltage signal applied to an input of the control circuit for a period of time until the desired output voltage of the power supply is reached. A second counter receives periodic signals from a second source and cyclicly counts a number of pulses equal to the count range between the upper and lower limits in the first counter within the time of a single s~cycle of alternating voltage applied to th0 input of the power supply. Each time a match is made between the count in the two counters a control signal is applied to the control input of the switch means to render the switch conductive until the end of the alternating voltage sub-cycle.
Circuitry provides for incrementing the first counter up to the upper limit and then decrementing it down to the lower limit and repeating the cycle as long as the level-setting voltage is applied to the input of the control circuit. Means are also provided for reversing the direction in which the first counter counts each time the level-settiny voltage is interrupted and then reapplied. Further means prevents the switching device from collducting each time the level-setting voltage is applied while the power supply is turned on to permit the same control motions by the user to alternately turn the p~wer supply on and off. Each time the pawer supply is turned on the output voltage is at its last level in the previous on-cycle by virtu~ of the count stored in ~le first counter.
The invention further teach~s in accordance with another 1387 P/7 ~A - 2 -~1~'75~6 aspec-t the.reof a system for controlling illumination of a lamp, or the like, which camprises a touch pad for contacting by a finger of the user, means for enabling switching the lamp to an illuminating ~cde upon finger oontact of the touch pad for a first relatively short time period, means for thereafter enabling switching the lamp from the illuminating mode to a non-illuminating mcde by finger contact of the touch pad for a second relatively short time period, and m~ans for enabling selected dimming of the illumination of the lamp after being s~itched to the illuminating mode by finger contact of the touch pad for a third relatively longer time period/ the first and second time periods being substantially and approximately equal to one another.
The invention still further teaches in accordance with another broad aspect thereof a method of controlling the illumination of a lamp, or the like, which camprises contacting a system touch pad for a first relatively short time period to switch a lamp fram a nan-illuminating mcde to an illuminating mcde, again contacting the system touch pad for a second,relatively lon~er time period cantrollable by the user to dim the lamp illumination, the level of illumination bei.ng a function of the duration of said second time period.
It is, therefore, an object of the invention to provide a variable voltage AC power supply having an output voltage variable in increasing and decreasing directions in response to the time during which a constant voltage level-setting signal is applied.
Another object of the invention is to provide a variable voltage AC power supply which, when initially actuated, produces an output voltage equal to the last produced output voltage.
Still another object of the invention is to provide a variable voltage AC power supply which can alternately be turned on and off by the same control motion.
A further object of the invention is to provide a variable voltage AC power supply wherein the direction of variation of voltage 75~6 reverses with respeet to the last direction of variation of voltage eaeh time the power supply is turned on.
Other and further objeets of the invention wil7 be apparent from the foll~ing drawings and deseription of a preferred embcdiment in whieh like referenee numerals are used to designate like parts in the various views.
DESCRIPTION OF THE DRAWINGS
-Fig. 1 ~ is a sehematie diagram of the eireuitry of the preferred embcdiment of the invention.
DESCRIPTICN OF THE PREFERRED EMECDIMENT
Referring now to the drawing, there is shown a standard AC voltage source 1 whieh ean be, for example, the line voltage supplied to a residence or ecmmereial building whieh is connected to an input terminal 3 of the variable voltage AC power supply of the invention.
m e input terminal 3 is eonneeted through a triae 5 to a load 7 whieh ean be of ineandeseent llght. m e triae 5, as will be known to those skilled in the art, has a control input 9 adapted to receive a voltage signal for rendering the triae eonductiv~. me triae, as will be further kncwn, is a latehing switeh deviee whieh remains conductive while a eurrent is flowing through it until current flcw ceases as, for example, during the zero erossing or ehange of polarity of an AC current passing through it. m e triac then beeomes non-conductive until once again latched into conduetion by applieation of a suitable pole at the control input 9.
A zero erossing detector eireuit 11 has an input whieh is also conneeted to the alternating voltage souree 3 and an output which is eonneeted to the reset input of a counter 13. m e zero crossing detector cireuit provides an output signal whenever the voltage of the source 3 changes polarity between positive and negative thereby assuming a momentary zero value. Zero crossing deteetors of this type are eonventional and known to those skilled in the art.
~'75 ~
Connected ~o the counting input of the counter 13 is the output of an oscillator 15 which has a ~requency equal to the product of twice the frequency of the AC voltage source 3 and the number of discrete output voltage levels which are to be supplied at the output of the variable voltage AC power supply.
The reason this frequency is chosen for the oscillator 15 will be apparent later in the disclosure when the functioning of the remaining circuitry is explained.
The counter 13 counts the output signals from the oscillator 15 which are supplied at the previously-defined frequency which in the case of a 60-cycle per second line connected to a variable voltage power supply according to the invention which has 64 output voltage levels is 7,680 cycles per second. The counter 13 counts the signals from the oscillator 15 ascendingly from zero to 64 and then automatically resets to æero and counts again to S4, the cycle being repeated as long as output signals are supplied by the oscillator 15. In this manner, the counter counts from zero to 64 once during each hal cycle of the 60-cycle ~C voltage of the source 3. The count is repeated during each sub-cycle which in the case of the sinosoidal AC voltage is selected to be a half cycle of the AC voltage. The sutput of the zero crossin~ detector 11 resets the counter 13 to zero for a new count to 64 at the commencement of each sub-cycle 25 of the ~C voltage.
The counter 13 is a conventional six-bit counter which can count 64 steps. The -counter 13 has a six-bit output which is connected to one input of a comparator 16. Another input of the comparator 16 is connected to the output o~ an 30 up-down counter 17 which has respective incrementing and decrementing inputs and a six-bit output which is applied to ~ 7 ~ ~ 6 the corresponding input of the six-bit comparatorl6. The compar~tor 16 has an output connected to one input o an AN~gatè l9. Whenever the six-bit output of the counter 13 " is identical to the six-bit output of the up-down counter 17, the comparator output is at one voltage equivalent to a logical "one". When the six-bit outputs of the counters 13 and 17 respec~ively differ, the output signal genera~ed by the comparator 16 is a different voltage which is equivalent ~o a logical "2ero".
Each time a signal is applied to the incrementing input of the up-down counter 17 on line 21, the co~mt in the up-down counter 17 is incremented by one. Each time a signal is applied on line 23 to the decrementing input the count in the up-down counter 17 is decremented by one.
Incrementing and decrementing signals are applied to the up-down counter 17 on lines 21 and 23 respectively by respective and gates25 and 27 each of which has four inputs.
In order for an ;ncrementing signal to appear on line 21 or lor a decrementing signal to appear on line 23, each of the 20 inputs to the respective AND gates 25and 27 must be equivalent to a log;cal "one" . The signals applied to the incrementing input o the up-down counter 17 on line 21 are employed to increase the output voltage of the variable voltage AC power supply of the invention and the signals on line 23 applied to 25 the decrementing input are used to decrease the power supply output voltage as will subse~uently be explained.
~ ~'759~6 The first of tlle input 29 of the AND gate 25 is connected to the Q output of a bi-stable multi-vibrator or flip-flop 31. The first of the inputs 33 to the AND
gate 27 is connected to the ~ output of the flip-flop 31 5 which is always equal to ~he inverse of the Q output.
With this arrangement, it will be appreciated that the output of AND gates 25 and 27 can never both be equivalent to logical "one" at the same time and hence the up down counter 17 will never receive incrementing and decrementing 10 signals simultaneously.
A second input 35 to AND gate 25 and a second input 37 to ~ND gate 27 are both connected to the output of an OR gate 38. Hence the respective signals on the second inputs 35 and 37 to AND gates 25 and 27 respectively are always the 15 same. A third input 3g to AND gate 25 and a third input 41 to AND gate 27 are each connected to the K output of a bi-stable n~llti-vibrator or flip-flop 43. Hence the signals applied to the respective inputs 39 and 41 of AND gates 25 and 27 are alsoalways the same. l'he fourth input 45 ~o AND gate 25 and 20 the fourth input 47 to AND gate 27 are each connected to the OlltpUt of a constant frequency o~cillator 49. Hence the signals at the inputs 45 and 47 to the respective AND gates 25 and 27 are again always the same.
The frequency of the oscillator 49 is equal to the 25 nu~ber of output voltage levels which are desired to be availablè at the output of the variable voltage AC power supply, which in the case of the preferred embodiment is ~7 S ~ 6 64, divided by the time in which it .is desired to have the output of the variable ~oltage power supply cycle between its lowest level and its h~ghest level. Tor a cycle ti~e from lowest voltage output to highest voltage output of 2-1/2 seconds, as has been determined to be convenient. the frequency of the oscillator 49 is selected to be 64, divided by 2.5 seconds or 25.6 cycles per second.
A step function signal generator 51 having an output which is normally equivalent-to the logical "zero" and changeable to a signal equivalent to a lo~ical "one" when actuated to turn the variable voltage AC power supply on or of or to vary its level of voltage can be a simple switch connected to a DC voltage source but can take many forms as will be known to those skilled in the art. Preferabl~, the step function generator 51 includes a pressure or temperature sens;tive switch which will actuate upon application of a light pressure or body tem ~ ature or ~ y capaci-tance when touched by a person. The signal gen~^ator 51 provides the stepped output signal equivalent to a logical "one" as long as the generator is continuously actuated as, for example, by continuously touching a temperature~sensitive or pressure sensitive surface of a switching device included therein.
The output of the stepped function signal 51 is connected directly to a first input 53 of an AND gate 55 and to a first input 57 of an ~D gate 59. The output of the stepped function generator 51 is also connected to the input of a first delay circuit 61 and to the input of a second delay circuit 63. The output of the first delay circuit 61 ~ 5 ~ 6 is connected ~o a second input 65 of the AND gate 55. The output of the second delay circuit 63 is connected to a second input 67 of the AND gate 59. The first delay cir~uit 61 provides a 65 mi.llisecond delay before producing at its output a stepp~d function signal similar to the one applied to its input from the output of the stepped function signal generator 51. A 65 millisecond delay is chosen for us in the case o~ a pressure-sensitive touch switch stepped function signal generator to prevent the output voltage of the variable voltage AC power supply from turning on and off during "f,inger bounce" wherein the pressure-sensitive switch surface may bounce several times ~len inger pressure is first applied before coming to rest in a stepped function generating position. That is, instead of a stepped function appearing at the output of the generator 51 when finger pressure is applied, a series of pulses may appear corresponding to the number of times the finger bounces on the surface, ~ 65 millisecond delay of the delay circuit 61 prevents suc~ pulses ~yhich normally d~ not occur 65 milliseconds after the switch surface is first touched causing an input to be applied to the second input 65 of the AND gate 55.
The second delay circuit 63 imparts a delay of 370 milliseconds be~ore reproducing the stepped voltage signal at its output for application to the second input 67 of AND
gate 59. 370 milliseconds is selected for the delay time imparted by the delay ci~cuits 63 as a dividing point between 1387 R/7 C~ - 9 -t~5~6 a momenta~y touch of the switching surface of the stepped function signal generator 51 and a continuous touching of the switching surface. A momentary touching of the switching surface of more than 65 milliseconds or less than 370 milli-seconds ~e~ult$ in the variable voltage ~C power supply beingturned on if it were previously off or off it it were previously on, as will subsequently be explained, while a continuous Louching after the voltage supply was turned of, not only turns it on but effects a continuous change in the output 10 voltage as long as pressure is applied to the pressure-sensitive surface of the stepped function signal generator 51.
Thus, to vary the voltage O~ltpUt of the power supply, the switch of the signal generator 51 must be actuated for a period of greater than 370 milliseconds. Although 65 milliseconds and 15 370 milliseconds have been determined to be convenient times *or respectively eliminating finger bounce problems and distinguishing betweèn momentary and continuous touching of the s~itching surface, other times may be selected within the teachings of the inven~ion, The construction of the delay 20 circuits 61 and 63 to achieve the desired time delays will be known to those skilled in the art as these are conventional devices commonly used with digital circuitry.
From the foregoing, it will be seen that in order to obtain a signal at the output of the AND gate 55 equivalent to 25 a logical "one" the step function signal generator 51 must be actuated for a period of time greater than 65 milliseconds so that signals equivalent to logical "one" appear at both inputs 53 and 65 to the AND gate 55.
~ 6 The output of the AND gate 55 is connected to the input of an inverting amplifier having a unity gain and known to those skilled in the art as an inverter 69. The output of the inverter 69 is always equal to the inverse of the input to the inverter 69 so that when a signal equivalent to a logical one appears at the output of the inverter 69 the output ofthe inverter 69 is equivalent to a logical zero.
Similarly, when the signal or lack o~ it at the input to the inverter 69 is equivalent to a logical zero,the out put of the inverter 6g generates a signal equivalent to a logical one. The output of the AND gate 55 is also connected to the input o a monostable ~lti-vibrator or one shot circui~ 71 which generates a pulse at its output of 305 milliseconds duration in response to a signal equivalent to a logical "one"
appearing at the input of the mono-stable multi-vibrator 71.
The output of the inverter 69 is applied to a first input 73 of an AND gate 75 and the output of the monostable multi-vibrator 71 is connected to a second input 77 of the AND gate 75. A net effect of this arrangement is to provide a signal at the output of AND gate 75 equivalent to a logical "one"
when the step function signal generator 61 is deactivated more than 65 milliseconds or less than 370 milliseconds after it is initially actuated. Only if the step function signal generator 51 is actuated for a period of time greater than 65 milliseconds 25 can a logical one signal appear at the output of AND gate 55.
This signal at the output of the AND gate 55 is necessary to actuaLe the monostable multi-vibrator 71 into producing at its output a 305 millisecond signal which is needed to provide a ~1 ~ 7~
logical "one" signal at ~he output of AND gate 75, However, while the step ~unction signal is appearing at the output of the step function signal ~enerator 51 after passage of the 65 millisecond initial delay period, the signal at the input 73 to thP AND gate 75 is equivalent to a logical "zero" due to the action of the inverter 69. Only when the step function signal generator 51 is deactuated during the occurrence of the 305 millisecond pulse at the output of the monostable multi-vibrator 71 to the signals at the inputs73 and 77 of the ~D gate 75 both 10 become equivalent to logical "one" thereby enabling a logical "one" signal to appear at the output of .AND gatc 75. After 370 milliseconds has elapsed fromthe time the step function signal generator 51 is first actuated, the 305 millisecond pulse from the monostable multi-vibrator 71 terminates thereby preventing 15 a logical "one" signal from appearing at the output o~ AND gate 75.
The signal ~t the output of AND gate 75 controls the on-off function of the variable voltage AC power supply o the invention as ollows.
~le OUtpllt of AND gate 75 is connected to the input 79 of an OR gate ~l. The OUtpllt o the OR gate 81 is connected to the input 20 of a pulse generating circuit 83 which can be a monostable multi-vibratcr or one-shot circuit. ~lenever a signal equivalent to a logical one appears at the output of the AND gate 75, a similar si~nal appears at the output of the OR gate 81 thereby actuat;ng the pulse generating circuit 83 to produce at its output a pulse 25 which is applied to the clock input C of the bistable multi-vibrator 43. The bistable multi-vibrator 43 is wired with its J input connected to the Q output and the K input o the bistable multi-vibrator 43 is connected to the K output. In this mode, ~ 5 ~ .
every time a puLse transition occurs at the clock input C o the bistable multi~vibrator 43, the outputs at Q and Q invert.
Thus, at the output ~ was originally a logical one and the output at Q was, by necessity, a logical "zero" upon application of a pulse fromthe pulse generator 83 to the clock input C of the bistable multi-vibrator 43, the output signal at the Q terminal of the multi-vobrator 43 would change from logical one to logical zero and the output at Q would change from logical zero to logical one. As previously indicated, the Q output of the bistable multi-vibrator 43 is connected to one input of the AND gate 19, the other input of which is connected to the output of the comparator 16~ The output of the AND gate 19 is connected to the control input 9 of the triac 5. Whenever,a signal equivalent to a logical one appears 15 at the output of the AND gate 19, the triac 5 is rendered conducting and the.variable voltage power aupply is turned on for the remaining duration of the instant subcycle o~ the alternating AC voltage applied to the triac 5; Xence, in order for the triac to be rendered eonducting, a match must be made 20 be~ween the count in the counter 13 and the count inthe up-down counter 17. As the count stored in the up-down counter 17 increases t~e triac S is rendered conducting at a later time in each alternating voltage subcycle and the root mean square voltage produced at the output of the variable voltage 25 AC power supply is diminished. If a pulse app~ars at the clock input C of the bistable multi-vibrator 43 while the Q output of the 'bistable multi-vibrator 43 has a logical "one"
signal permittin~ triac to be rendered conducting by a ~atch between the counters 13 and 17, the output signal at the Q
terminal is inverted to a logical "zero" thereby preventing the triac from being rendered conducting upon the next occurrence of a match between the counts in the respective counters 13 and 17.
If the step function signal generator Sl is actuated for a period of time greater than 370 milliseconds, as previously indicated, the output of the AND gate 75 will remain at logical zero. However, a signal equivalent to a logical "one" will appear at the out put of the AND gate 59 and will be applied to a first input 85 of an ANDgate 87. The second input 89 of the AND gate 87 is connected to an input 91 of the OR gate 81.
Hence, whenever a logical "onel' signal appears at the output of the AND gate 87, a similar signal appears at the output of the OR gate 81 which is applied to the input ~ the pulse generating circuit 83 to cause the bistable multi-vibrator 43 to toggle, that is, to invert its output signals. The Q output of the bistable multi-vibrator 43 is connected to the second input 89 of the AND gate 87 so that a logical "one"
signal can appear at the output oE the AND gate 87 to actuate the pulse generator 83 only when the Q output si~nal of ~he bistable multi-vibrator 43 is a logical "one", that is, only when the triac 5 is prevented from bein.g rendered conducting by matched counts in the counters 13 and 17,respectively, in which condition the variable voltage AC power supply is off.
Hence, if the power supply is on and it is desired to vary the voltage of the output and not to turn off the power supply, ~he step function signal generator 51 can be actuated for a period ~ 1 ~'75~6 of time more than 370 ~illiseconds during and after which the respective signals appearing at the outputs of ~ND gates 75 and 87 will both have a value of logical "zero" thereby preventing the pulse generator 38 from toggling the bistable 5 multi-vibrator 43 thereby permitting the triac to continue ~
being conductive in each succeeding subcycle of the alternating voltage from the time a ma~ch occ~rs between the counts in the counters 13 and 17.
The output of AND gate 59 is connected to a first lQ input 93 of an OR gate 38 and an end-of-count output of the up-down counter 17 is connected to a second input 97 of the ORgate 38. The output of the OR gate 38 is connected to the input of a pulse generator circuit 99 which can be a mono-stable multi-vibrator. The output of the pulse generator circuit 99 is connected to the clock input of the bistable multi-vibrator or fli~-flop 31. The bistable multi-vibrator 31 has its J input wired to the ~ output and the K input wired to the Q output in a manner similar to the bistable multi-vibra~or or flip-flop 43 and functions similarly to the flipflop 43 in that each time a pulse is applied to th~ clock input C of the multi-vibrator 31 the mutually opposite output signals at the Q and ~ outputs are inverted.
As previusly explained in connection with the discussion of AND Gates 25 and 27, depending upon the signals at the Q and outputs of the flip-flop 31, one and only one of the AND gates 25 and 27 is capable of passing pulses supplied at its input. The pulses which are used for incrementing and decre~enting the up-down counter 17 are provided by the constant frequency oscillator 49.
'75~6 The flip~flop 31 controls whether the up-down counter 17 is incre~ented or decremented by the pulses emanating from the oscillator 49. When the Q output has a logical value of "one"
and the Q output has a logical value of "zero",only incrementing 5 pulses c~n be applied t~ the up-down counter 17. 5imilarly, when the Q output has a logical ~alue of !'zero" and the Q output of the fli-10p 31 has a lo~ical value of "one", only decrementing pulses can be applied to the up-down counters 17.
The alternating voltage provided at the output of the 10 variable voltage AC power supply can be varied between zero volts and the maximum line voltage in any number of discrete steps.
In the example of the preferred embodiment, sixty-four steps were chosen, the voltage levels associated with adjacent steps being so close together as to, for most practical purposes, give 15 the equivalent of a continuous voltage variation particularly-when used for dimming incandescent lamps. With the power supply off, the ~lip-flop 43 is in its one bistable state wherein the output signal at Q is a logical "one" and the o-ltput at the Q
terminal is a logical "zero". As previusly explained, this 20 prevents the triac 5 from being rendered conductive. To turn the power supply on as, for example, to light a lamp, the step function signal generator is actuated as by touching it momentarily for a period of time greater than 65 milliseconds but less than 370 milliseconds. This causes a pulse to be generated by the 25 pulse generator 83 in reponse to a logical "one" signal appearing at the output of AND gate 75thereby toggling thè flip-flop 43 and providing a logical "one" signal to one input of the AND
gate 19~ At this time, the count in the up-down counter 17 is r'J~
constant having a stored value equal to ~he last value obtained and the counter 13 is continuously counting between zero and sixty-four, the counter 13 be;ng reset each time a zero crossing of the AC voltage is detected by the zero crossing detector 11.
The time to count from zero to sixty~four is equal to the time of one-half cycle of the alternating voltage or the time between zero crossing, Each time the counter 13 reaches the count equal to the count stored in the up-down counter 17 a pulse is generated at the output of the comparator 16 and applied to the other input 10 of the AND gate 19 thereby rendering the tr.iac 5 conductive.
The powersupply is turned on and has at its output an average voltage dependent upon the counts stored in the up-down counter 17.
~le higher the count in the up-down counter 17 the less is.the output voltage of the power supply. To change the output voltage 15 the step unction signal generator is actuated for a period of time greater than 370 milliseconds at which time a pulse is generated by the pulse generator g9 to~gling the flîp-flop 31.
Concurrently, a logical "one" pulse appears at the output of the OR gate 95 thercby enabling whichever of the AND gates 25 and 27 20 is connected to the output of the flip-flop 31 having a logical "one" value to transmit pulses from the oscillator 49 ~o either the incrementing or decrementing input of the up-down counter.
if the voltage output of the power supply was last changed in an increasing direction, the toggling of the flip-flop will cause
___ __ ______ _ The instant invention pertains to the art of variable voltage ~C power supply having an input at which an AC voltage is applied and an output at which a voltage of variable magnitude can be used to power an applian oe. The type of variable voltage p~wer supply with which the invention deals applies particularly to devices used for dimming incandescent lights in a plant or residence.
Various types of devices for dimming lights are kncwn to the art including variable transfoxmers, rheostats and those employing high-speed switchiny devices such as silicon-controlled rectifiers and triacs.
In prior art devices employing high-speed switching devices to disconnect the line voltage from the appliance during portions of the alternating voltage cycle, a control must normally be turned or otherwise moved to a position consistent with the turn-on point of the switching device in the AC cycle. Although useful for some applicatio~s, these devices have shortcom m gs which render them difficult to-use in others.
For example, if the level of light is to be controlled from a remote location, radio controlled servo-motors must be used to position the control.
Prior art devices also do not lend themselves -to use with touch-actuated controls which can provide a constant voltage signal during the duration of a pressure, temperature or body capacitance applied to the surface of the controls. Such controls, in addition to their utility, are aesthetically pleasing particularly when used in mcdern decors.
SU~ RY OF T~E ~ rIO~
~5 m e instant invention teaches in accordance with one aspect thereof the construction and use of a variable voltage power supply having an input adapted to be connected to an alternating voltage and an output, a latching switch means having one terminal connected to the input and another termunal connected to the output and a control terminal to which a control voltage is applied for latching the switch in a closed condition tjJ~S~
at a preset time ~l a sub-cycle of the line-alternating voltage. The switch means chanyes to an open state from a closed state to interrupt current flow to the output of the power supply during the zero crossing which tenmnates the alternating voltage sub,cycle. The control circuit includes a source of periodic signals and a counter to which signals are applied for incrementing and then decrementing the count in the counter between lower and upper counting limits in response to application of a level-setting constant voltage signal applied to an input of the control circuit for a period of time until the desired output voltage of the power supply is reached. A second counter receives periodic signals from a second source and cyclicly counts a number of pulses equal to the count range between the upper and lower limits in the first counter within the time of a single s~cycle of alternating voltage applied to th0 input of the power supply. Each time a match is made between the count in the two counters a control signal is applied to the control input of the switch means to render the switch conductive until the end of the alternating voltage sub-cycle.
Circuitry provides for incrementing the first counter up to the upper limit and then decrementing it down to the lower limit and repeating the cycle as long as the level-setting voltage is applied to the input of the control circuit. Means are also provided for reversing the direction in which the first counter counts each time the level-settiny voltage is interrupted and then reapplied. Further means prevents the switching device from collducting each time the level-setting voltage is applied while the power supply is turned on to permit the same control motions by the user to alternately turn the p~wer supply on and off. Each time the pawer supply is turned on the output voltage is at its last level in the previous on-cycle by virtu~ of the count stored in ~le first counter.
The invention further teach~s in accordance with another 1387 P/7 ~A - 2 -~1~'75~6 aspec-t the.reof a system for controlling illumination of a lamp, or the like, which camprises a touch pad for contacting by a finger of the user, means for enabling switching the lamp to an illuminating ~cde upon finger oontact of the touch pad for a first relatively short time period, means for thereafter enabling switching the lamp from the illuminating mode to a non-illuminating mcde by finger contact of the touch pad for a second relatively short time period, and m~ans for enabling selected dimming of the illumination of the lamp after being s~itched to the illuminating mode by finger contact of the touch pad for a third relatively longer time period/ the first and second time periods being substantially and approximately equal to one another.
The invention still further teaches in accordance with another broad aspect thereof a method of controlling the illumination of a lamp, or the like, which camprises contacting a system touch pad for a first relatively short time period to switch a lamp fram a nan-illuminating mcde to an illuminating mcde, again contacting the system touch pad for a second,relatively lon~er time period cantrollable by the user to dim the lamp illumination, the level of illumination bei.ng a function of the duration of said second time period.
It is, therefore, an object of the invention to provide a variable voltage AC power supply having an output voltage variable in increasing and decreasing directions in response to the time during which a constant voltage level-setting signal is applied.
Another object of the invention is to provide a variable voltage AC power supply which, when initially actuated, produces an output voltage equal to the last produced output voltage.
Still another object of the invention is to provide a variable voltage AC power supply which can alternately be turned on and off by the same control motion.
A further object of the invention is to provide a variable voltage AC power supply wherein the direction of variation of voltage 75~6 reverses with respeet to the last direction of variation of voltage eaeh time the power supply is turned on.
Other and further objeets of the invention wil7 be apparent from the foll~ing drawings and deseription of a preferred embcdiment in whieh like referenee numerals are used to designate like parts in the various views.
DESCRIPTION OF THE DRAWINGS
-Fig. 1 ~ is a sehematie diagram of the eireuitry of the preferred embcdiment of the invention.
DESCRIPTICN OF THE PREFERRED EMECDIMENT
Referring now to the drawing, there is shown a standard AC voltage source 1 whieh ean be, for example, the line voltage supplied to a residence or ecmmereial building whieh is connected to an input terminal 3 of the variable voltage AC power supply of the invention.
m e input terminal 3 is eonneeted through a triae 5 to a load 7 whieh ean be of ineandeseent llght. m e triae 5, as will be known to those skilled in the art, has a control input 9 adapted to receive a voltage signal for rendering the triae eonductiv~. me triae, as will be further kncwn, is a latehing switeh deviee whieh remains conductive while a eurrent is flowing through it until current flcw ceases as, for example, during the zero erossing or ehange of polarity of an AC current passing through it. m e triac then beeomes non-conductive until once again latched into conduetion by applieation of a suitable pole at the control input 9.
A zero erossing detector eireuit 11 has an input whieh is also conneeted to the alternating voltage souree 3 and an output which is eonneeted to the reset input of a counter 13. m e zero crossing detector cireuit provides an output signal whenever the voltage of the source 3 changes polarity between positive and negative thereby assuming a momentary zero value. Zero crossing deteetors of this type are eonventional and known to those skilled in the art.
~'75 ~
Connected ~o the counting input of the counter 13 is the output of an oscillator 15 which has a ~requency equal to the product of twice the frequency of the AC voltage source 3 and the number of discrete output voltage levels which are to be supplied at the output of the variable voltage AC power supply.
The reason this frequency is chosen for the oscillator 15 will be apparent later in the disclosure when the functioning of the remaining circuitry is explained.
The counter 13 counts the output signals from the oscillator 15 which are supplied at the previously-defined frequency which in the case of a 60-cycle per second line connected to a variable voltage power supply according to the invention which has 64 output voltage levels is 7,680 cycles per second. The counter 13 counts the signals from the oscillator 15 ascendingly from zero to 64 and then automatically resets to æero and counts again to S4, the cycle being repeated as long as output signals are supplied by the oscillator 15. In this manner, the counter counts from zero to 64 once during each hal cycle of the 60-cycle ~C voltage of the source 3. The count is repeated during each sub-cycle which in the case of the sinosoidal AC voltage is selected to be a half cycle of the AC voltage. The sutput of the zero crossin~ detector 11 resets the counter 13 to zero for a new count to 64 at the commencement of each sub-cycle 25 of the ~C voltage.
The counter 13 is a conventional six-bit counter which can count 64 steps. The -counter 13 has a six-bit output which is connected to one input of a comparator 16. Another input of the comparator 16 is connected to the output o~ an 30 up-down counter 17 which has respective incrementing and decrementing inputs and a six-bit output which is applied to ~ 7 ~ ~ 6 the corresponding input of the six-bit comparatorl6. The compar~tor 16 has an output connected to one input o an AN~gatè l9. Whenever the six-bit output of the counter 13 " is identical to the six-bit output of the up-down counter 17, the comparator output is at one voltage equivalent to a logical "one". When the six-bit outputs of the counters 13 and 17 respec~ively differ, the output signal genera~ed by the comparator 16 is a different voltage which is equivalent ~o a logical "2ero".
Each time a signal is applied to the incrementing input of the up-down counter 17 on line 21, the co~mt in the up-down counter 17 is incremented by one. Each time a signal is applied on line 23 to the decrementing input the count in the up-down counter 17 is decremented by one.
Incrementing and decrementing signals are applied to the up-down counter 17 on lines 21 and 23 respectively by respective and gates25 and 27 each of which has four inputs.
In order for an ;ncrementing signal to appear on line 21 or lor a decrementing signal to appear on line 23, each of the 20 inputs to the respective AND gates 25and 27 must be equivalent to a log;cal "one" . The signals applied to the incrementing input o the up-down counter 17 on line 21 are employed to increase the output voltage of the variable voltage AC power supply of the invention and the signals on line 23 applied to 25 the decrementing input are used to decrease the power supply output voltage as will subse~uently be explained.
~ ~'759~6 The first of tlle input 29 of the AND gate 25 is connected to the Q output of a bi-stable multi-vibrator or flip-flop 31. The first of the inputs 33 to the AND
gate 27 is connected to the ~ output of the flip-flop 31 5 which is always equal to ~he inverse of the Q output.
With this arrangement, it will be appreciated that the output of AND gates 25 and 27 can never both be equivalent to logical "one" at the same time and hence the up down counter 17 will never receive incrementing and decrementing 10 signals simultaneously.
A second input 35 to AND gate 25 and a second input 37 to ~ND gate 27 are both connected to the output of an OR gate 38. Hence the respective signals on the second inputs 35 and 37 to AND gates 25 and 27 respectively are always the 15 same. A third input 3g to AND gate 25 and a third input 41 to AND gate 27 are each connected to the K output of a bi-stable n~llti-vibrator or flip-flop 43. Hence the signals applied to the respective inputs 39 and 41 of AND gates 25 and 27 are alsoalways the same. l'he fourth input 45 ~o AND gate 25 and 20 the fourth input 47 to AND gate 27 are each connected to the OlltpUt of a constant frequency o~cillator 49. Hence the signals at the inputs 45 and 47 to the respective AND gates 25 and 27 are again always the same.
The frequency of the oscillator 49 is equal to the 25 nu~ber of output voltage levels which are desired to be availablè at the output of the variable voltage AC power supply, which in the case of the preferred embodiment is ~7 S ~ 6 64, divided by the time in which it .is desired to have the output of the variable ~oltage power supply cycle between its lowest level and its h~ghest level. Tor a cycle ti~e from lowest voltage output to highest voltage output of 2-1/2 seconds, as has been determined to be convenient. the frequency of the oscillator 49 is selected to be 64, divided by 2.5 seconds or 25.6 cycles per second.
A step function signal generator 51 having an output which is normally equivalent-to the logical "zero" and changeable to a signal equivalent to a lo~ical "one" when actuated to turn the variable voltage AC power supply on or of or to vary its level of voltage can be a simple switch connected to a DC voltage source but can take many forms as will be known to those skilled in the art. Preferabl~, the step function generator 51 includes a pressure or temperature sens;tive switch which will actuate upon application of a light pressure or body tem ~ ature or ~ y capaci-tance when touched by a person. The signal gen~^ator 51 provides the stepped output signal equivalent to a logical "one" as long as the generator is continuously actuated as, for example, by continuously touching a temperature~sensitive or pressure sensitive surface of a switching device included therein.
The output of the stepped function signal 51 is connected directly to a first input 53 of an AND gate 55 and to a first input 57 of an ~D gate 59. The output of the stepped function generator 51 is also connected to the input of a first delay circuit 61 and to the input of a second delay circuit 63. The output of the first delay circuit 61 ~ 5 ~ 6 is connected ~o a second input 65 of the AND gate 55. The output of the second delay circuit 63 is connected to a second input 67 of the AND gate 59. The first delay cir~uit 61 provides a 65 mi.llisecond delay before producing at its output a stepp~d function signal similar to the one applied to its input from the output of the stepped function signal generator 51. A 65 millisecond delay is chosen for us in the case o~ a pressure-sensitive touch switch stepped function signal generator to prevent the output voltage of the variable voltage AC power supply from turning on and off during "f,inger bounce" wherein the pressure-sensitive switch surface may bounce several times ~len inger pressure is first applied before coming to rest in a stepped function generating position. That is, instead of a stepped function appearing at the output of the generator 51 when finger pressure is applied, a series of pulses may appear corresponding to the number of times the finger bounces on the surface, ~ 65 millisecond delay of the delay circuit 61 prevents suc~ pulses ~yhich normally d~ not occur 65 milliseconds after the switch surface is first touched causing an input to be applied to the second input 65 of the AND gate 55.
The second delay circuit 63 imparts a delay of 370 milliseconds be~ore reproducing the stepped voltage signal at its output for application to the second input 67 of AND
gate 59. 370 milliseconds is selected for the delay time imparted by the delay ci~cuits 63 as a dividing point between 1387 R/7 C~ - 9 -t~5~6 a momenta~y touch of the switching surface of the stepped function signal generator 51 and a continuous touching of the switching surface. A momentary touching of the switching surface of more than 65 milliseconds or less than 370 milli-seconds ~e~ult$ in the variable voltage ~C power supply beingturned on if it were previously off or off it it were previously on, as will subsequently be explained, while a continuous Louching after the voltage supply was turned of, not only turns it on but effects a continuous change in the output 10 voltage as long as pressure is applied to the pressure-sensitive surface of the stepped function signal generator 51.
Thus, to vary the voltage O~ltpUt of the power supply, the switch of the signal generator 51 must be actuated for a period of greater than 370 milliseconds. Although 65 milliseconds and 15 370 milliseconds have been determined to be convenient times *or respectively eliminating finger bounce problems and distinguishing betweèn momentary and continuous touching of the s~itching surface, other times may be selected within the teachings of the inven~ion, The construction of the delay 20 circuits 61 and 63 to achieve the desired time delays will be known to those skilled in the art as these are conventional devices commonly used with digital circuitry.
From the foregoing, it will be seen that in order to obtain a signal at the output of the AND gate 55 equivalent to 25 a logical "one" the step function signal generator 51 must be actuated for a period of time greater than 65 milliseconds so that signals equivalent to logical "one" appear at both inputs 53 and 65 to the AND gate 55.
~ 6 The output of the AND gate 55 is connected to the input of an inverting amplifier having a unity gain and known to those skilled in the art as an inverter 69. The output of the inverter 69 is always equal to the inverse of the input to the inverter 69 so that when a signal equivalent to a logical one appears at the output of the inverter 69 the output ofthe inverter 69 is equivalent to a logical zero.
Similarly, when the signal or lack o~ it at the input to the inverter 69 is equivalent to a logical zero,the out put of the inverter 6g generates a signal equivalent to a logical one. The output of the AND gate 55 is also connected to the input o a monostable ~lti-vibrator or one shot circui~ 71 which generates a pulse at its output of 305 milliseconds duration in response to a signal equivalent to a logical "one"
appearing at the input of the mono-stable multi-vibrator 71.
The output of the inverter 69 is applied to a first input 73 of an AND gate 75 and the output of the monostable multi-vibrator 71 is connected to a second input 77 of the AND gate 75. A net effect of this arrangement is to provide a signal at the output of AND gate 75 equivalent to a logical "one"
when the step function signal generator 61 is deactivated more than 65 milliseconds or less than 370 milliseconds after it is initially actuated. Only if the step function signal generator 51 is actuated for a period of time greater than 65 milliseconds 25 can a logical one signal appear at the output of AND gate 55.
This signal at the output of the AND gate 55 is necessary to actuaLe the monostable multi-vibrator 71 into producing at its output a 305 millisecond signal which is needed to provide a ~1 ~ 7~
logical "one" signal at ~he output of AND gate 75, However, while the step ~unction signal is appearing at the output of the step function signal ~enerator 51 after passage of the 65 millisecond initial delay period, the signal at the input 73 to thP AND gate 75 is equivalent to a logical "zero" due to the action of the inverter 69. Only when the step function signal generator 51 is deactuated during the occurrence of the 305 millisecond pulse at the output of the monostable multi-vibrator 71 to the signals at the inputs73 and 77 of the ~D gate 75 both 10 become equivalent to logical "one" thereby enabling a logical "one" signal to appear at the output of .AND gatc 75. After 370 milliseconds has elapsed fromthe time the step function signal generator 51 is first actuated, the 305 millisecond pulse from the monostable multi-vibrator 71 terminates thereby preventing 15 a logical "one" signal from appearing at the output o~ AND gate 75.
The signal ~t the output of AND gate 75 controls the on-off function of the variable voltage AC power supply o the invention as ollows.
~le OUtpllt of AND gate 75 is connected to the input 79 of an OR gate ~l. The OUtpllt o the OR gate 81 is connected to the input 20 of a pulse generating circuit 83 which can be a monostable multi-vibratcr or one-shot circuit. ~lenever a signal equivalent to a logical one appears at the output of the AND gate 75, a similar si~nal appears at the output of the OR gate 81 thereby actuat;ng the pulse generating circuit 83 to produce at its output a pulse 25 which is applied to the clock input C of the bistable multi-vibrator 43. The bistable multi-vibrator 43 is wired with its J input connected to the Q output and the K input o the bistable multi-vibrator 43 is connected to the K output. In this mode, ~ 5 ~ .
every time a puLse transition occurs at the clock input C o the bistable multi~vibrator 43, the outputs at Q and Q invert.
Thus, at the output ~ was originally a logical one and the output at Q was, by necessity, a logical "zero" upon application of a pulse fromthe pulse generator 83 to the clock input C of the bistable multi-vibrator 43, the output signal at the Q terminal of the multi-vobrator 43 would change from logical one to logical zero and the output at Q would change from logical zero to logical one. As previously indicated, the Q output of the bistable multi-vibrator 43 is connected to one input of the AND gate 19, the other input of which is connected to the output of the comparator 16~ The output of the AND gate 19 is connected to the control input 9 of the triac 5. Whenever,a signal equivalent to a logical one appears 15 at the output of the AND gate 19, the triac 5 is rendered conducting and the.variable voltage power aupply is turned on for the remaining duration of the instant subcycle o~ the alternating AC voltage applied to the triac 5; Xence, in order for the triac to be rendered eonducting, a match must be made 20 be~ween the count in the counter 13 and the count inthe up-down counter 17. As the count stored in the up-down counter 17 increases t~e triac S is rendered conducting at a later time in each alternating voltage subcycle and the root mean square voltage produced at the output of the variable voltage 25 AC power supply is diminished. If a pulse app~ars at the clock input C of the bistable multi-vibrator 43 while the Q output of the 'bistable multi-vibrator 43 has a logical "one"
signal permittin~ triac to be rendered conducting by a ~atch between the counters 13 and 17, the output signal at the Q
terminal is inverted to a logical "zero" thereby preventing the triac from being rendered conducting upon the next occurrence of a match between the counts in the respective counters 13 and 17.
If the step function signal generator Sl is actuated for a period of time greater than 370 milliseconds, as previously indicated, the output of the AND gate 75 will remain at logical zero. However, a signal equivalent to a logical "one" will appear at the out put of the AND gate 59 and will be applied to a first input 85 of an ANDgate 87. The second input 89 of the AND gate 87 is connected to an input 91 of the OR gate 81.
Hence, whenever a logical "onel' signal appears at the output of the AND gate 87, a similar signal appears at the output of the OR gate 81 which is applied to the input ~ the pulse generating circuit 83 to cause the bistable multi-vibrator 43 to toggle, that is, to invert its output signals. The Q output of the bistable multi-vibrator 43 is connected to the second input 89 of the AND gate 87 so that a logical "one"
signal can appear at the output oE the AND gate 87 to actuate the pulse generator 83 only when the Q output si~nal of ~he bistable multi-vibrator 43 is a logical "one", that is, only when the triac 5 is prevented from bein.g rendered conducting by matched counts in the counters 13 and 17,respectively, in which condition the variable voltage AC power supply is off.
Hence, if the power supply is on and it is desired to vary the voltage of the output and not to turn off the power supply, ~he step function signal generator 51 can be actuated for a period ~ 1 ~'75~6 of time more than 370 ~illiseconds during and after which the respective signals appearing at the outputs of ~ND gates 75 and 87 will both have a value of logical "zero" thereby preventing the pulse generator 38 from toggling the bistable 5 multi-vibrator 43 thereby permitting the triac to continue ~
being conductive in each succeeding subcycle of the alternating voltage from the time a ma~ch occ~rs between the counts in the counters 13 and 17.
The output of AND gate 59 is connected to a first lQ input 93 of an OR gate 38 and an end-of-count output of the up-down counter 17 is connected to a second input 97 of the ORgate 38. The output of the OR gate 38 is connected to the input of a pulse generator circuit 99 which can be a mono-stable multi-vibrator. The output of the pulse generator circuit 99 is connected to the clock input of the bistable multi-vibrator or fli~-flop 31. The bistable multi-vibrator 31 has its J input wired to the ~ output and the K input wired to the Q output in a manner similar to the bistable multi-vibra~or or flip-flop 43 and functions similarly to the flipflop 43 in that each time a pulse is applied to th~ clock input C of the multi-vibrator 31 the mutually opposite output signals at the Q and ~ outputs are inverted.
As previusly explained in connection with the discussion of AND Gates 25 and 27, depending upon the signals at the Q and outputs of the flip-flop 31, one and only one of the AND gates 25 and 27 is capable of passing pulses supplied at its input. The pulses which are used for incrementing and decre~enting the up-down counter 17 are provided by the constant frequency oscillator 49.
'75~6 The flip~flop 31 controls whether the up-down counter 17 is incre~ented or decremented by the pulses emanating from the oscillator 49. When the Q output has a logical value of "one"
and the Q output has a logical value of "zero",only incrementing 5 pulses c~n be applied t~ the up-down counter 17. 5imilarly, when the Q output has a logical ~alue of !'zero" and the Q output of the fli-10p 31 has a lo~ical value of "one", only decrementing pulses can be applied to the up-down counters 17.
The alternating voltage provided at the output of the 10 variable voltage AC power supply can be varied between zero volts and the maximum line voltage in any number of discrete steps.
In the example of the preferred embodiment, sixty-four steps were chosen, the voltage levels associated with adjacent steps being so close together as to, for most practical purposes, give 15 the equivalent of a continuous voltage variation particularly-when used for dimming incandescent lamps. With the power supply off, the ~lip-flop 43 is in its one bistable state wherein the output signal at Q is a logical "one" and the o-ltput at the Q
terminal is a logical "zero". As previusly explained, this 20 prevents the triac 5 from being rendered conductive. To turn the power supply on as, for example, to light a lamp, the step function signal generator is actuated as by touching it momentarily for a period of time greater than 65 milliseconds but less than 370 milliseconds. This causes a pulse to be generated by the 25 pulse generator 83 in reponse to a logical "one" signal appearing at the output of AND gate 75thereby toggling thè flip-flop 43 and providing a logical "one" signal to one input of the AND
gate 19~ At this time, the count in the up-down counter 17 is r'J~
constant having a stored value equal to ~he last value obtained and the counter 13 is continuously counting between zero and sixty-four, the counter 13 be;ng reset each time a zero crossing of the AC voltage is detected by the zero crossing detector 11.
The time to count from zero to sixty~four is equal to the time of one-half cycle of the alternating voltage or the time between zero crossing, Each time the counter 13 reaches the count equal to the count stored in the up-down counter 17 a pulse is generated at the output of the comparator 16 and applied to the other input 10 of the AND gate 19 thereby rendering the tr.iac 5 conductive.
The powersupply is turned on and has at its output an average voltage dependent upon the counts stored in the up-down counter 17.
~le higher the count in the up-down counter 17 the less is.the output voltage of the power supply. To change the output voltage 15 the step unction signal generator is actuated for a period of time greater than 370 milliseconds at which time a pulse is generated by the pulse generator g9 to~gling the flîp-flop 31.
Concurrently, a logical "one" pulse appears at the output of the OR gate 95 thercby enabling whichever of the AND gates 25 and 27 20 is connected to the output of the flip-flop 31 having a logical "one" value to transmit pulses from the oscillator 49 ~o either the incrementing or decrementing input of the up-down counter.
if the voltage output of the power supply was last changed in an increasing direction, the toggling of the flip-flop will cause
2~ the pulses from the oscillator 49 to be applied to the AND gate 27 on line 23 to decrement the up-down counter. Si~ilarly~ i~
during the last voltage change the voltage was changed in a decreasing direction,` toggling of the flip-flop 31 will result __ 13~7 P/7 c~ - 17 -~ 5~ ~
in a logical '`one". value appearing at the Q output thereby enabling AND gate 25 to pass pulses from the oscillator 49 to the incrementing input of the up-down counter. If it is desired to reduce the voltage output and the flip-flp 31 5 is set so that the voltage output is increasing, all that need be done to reverse the direction is ~o interrupt the step voltage from the step function signal generator as, for exa~ple~
by removing the hand from the touch sensitive surface of the pressure sensitive switch, and then.to reactuate the step 10 function signal generator, as by reapplying the hand, for a period.of more than 370 milliseconds. This will toggle the flip-flop 31 again and change the direction of voltage variation by changing the direction in which the up-down counter counts between zero and sixty-four. While the step function signal generator 51 is being actuated after 370 milliseconds, the up-down counter counts and if the count is an ascending one, a match is made with the count in the coun~ of thirteen later into half cy cles of the alternating voltage thereby shortening the time during each half-cycle during which the triac conducts. If the 20 counter is counting in a descending direction, matches are made between the count in : the count of thirteen and the counter 17 successively earlier in succeeding alternating voltage sub-cycles thereby increasing the time in each half cycle in which the triac is rendered conductive and, hence> increasing the output voltage 25Of the variable voltage power supply. Once the desired voltage level at the output is reached, the step f~mction signal generator 51 is deactivated, by removing the hand fromthe switch, thereby ~erminating the step signal at which time there is a cessation of ~ ~ 4 ~
incrementing and decrementing pulses to the up-down counter and the count in the up-down counter remains constant and, therefore, so does the output voltage. To turn the power supply off, the step function signal generator 51 is actuated 5 for a brief period of time between 65 milliseconds and 370 ~illiseconds thereby causing the flip-flop 43 to toggle and the output of the AND gate 19 to go ~o logical "zero" whereby the triac can no longer be rendered conducting upon occurrence of a match in the counts of the counters 13 and 17.
. lO A conventional air gap switch 100 which can be mechani-cally actuated can be-connected in series be~ween the power supply and the voltage source 1. The switch lO0 is normally closed and the power supply is operated by actuating the step ~unction signal generator 51. However, when it is desired - 15 to totally disconnect the power supply from the A.C. source 1, the switch 100 can be opened.
It will be appreciated that variations and ~lterations to the disclosed preferred embodiment of the invention can be made without departin~ fro~ the spirit and scope of the invention.
1387 P/7 CA - l9 -
during the last voltage change the voltage was changed in a decreasing direction,` toggling of the flip-flop 31 will result __ 13~7 P/7 c~ - 17 -~ 5~ ~
in a logical '`one". value appearing at the Q output thereby enabling AND gate 25 to pass pulses from the oscillator 49 to the incrementing input of the up-down counter. If it is desired to reduce the voltage output and the flip-flp 31 5 is set so that the voltage output is increasing, all that need be done to reverse the direction is ~o interrupt the step voltage from the step function signal generator as, for exa~ple~
by removing the hand from the touch sensitive surface of the pressure sensitive switch, and then.to reactuate the step 10 function signal generator, as by reapplying the hand, for a period.of more than 370 milliseconds. This will toggle the flip-flop 31 again and change the direction of voltage variation by changing the direction in which the up-down counter counts between zero and sixty-four. While the step function signal generator 51 is being actuated after 370 milliseconds, the up-down counter counts and if the count is an ascending one, a match is made with the count in the coun~ of thirteen later into half cy cles of the alternating voltage thereby shortening the time during each half-cycle during which the triac conducts. If the 20 counter is counting in a descending direction, matches are made between the count in : the count of thirteen and the counter 17 successively earlier in succeeding alternating voltage sub-cycles thereby increasing the time in each half cycle in which the triac is rendered conductive and, hence> increasing the output voltage 25Of the variable voltage power supply. Once the desired voltage level at the output is reached, the step f~mction signal generator 51 is deactivated, by removing the hand fromthe switch, thereby ~erminating the step signal at which time there is a cessation of ~ ~ 4 ~
incrementing and decrementing pulses to the up-down counter and the count in the up-down counter remains constant and, therefore, so does the output voltage. To turn the power supply off, the step function signal generator 51 is actuated 5 for a brief period of time between 65 milliseconds and 370 ~illiseconds thereby causing the flip-flop 43 to toggle and the output of the AND gate 19 to go ~o logical "zero" whereby the triac can no longer be rendered conducting upon occurrence of a match in the counts of the counters 13 and 17.
. lO A conventional air gap switch 100 which can be mechani-cally actuated can be-connected in series be~ween the power supply and the voltage source 1. The switch lO0 is normally closed and the power supply is operated by actuating the step ~unction signal generator 51. However, when it is desired - 15 to totally disconnect the power supply from the A.C. source 1, the switch 100 can be opened.
It will be appreciated that variations and ~lterations to the disclosed preferred embodiment of the invention can be made without departin~ fro~ the spirit and scope of the invention.
1387 P/7 CA - l9 -
Claims (10)
1. A variable voltage power supply comprising:
an input adapted to be connected to an alternating voltage, an output, a latching switch means having one terminal connected to said input, another terminal connected to said output, and a control terminal adapted to have applied to it a control voltage for latching said switch means in a closed condition to permit current flow between said input and said output during a sub-cycle of said alternating voltage, said switch means switching to an open condition to prevent further current flow therethrough in response to completion of said sub-cycle of said alternating voltage, and a control circuit for actuating said latching switch means into a closed condition during each said sub-cycle including a first source of periodic signals having an output, a first counter for receiving and counting said periodic elect-rical signals from said first source, a second source of periodic electrical signals having an output, a second counter responsive to said second source of periodic signals for receiving and counting said periodic electrical signals from said second source, a comparator for comparing the count in said first counter with the count in said second counter, and means responsive to said comparator for applying a signal to said control terminal to latch said switch means into a conducting condition whenever the count in said first counter equals the count in said second counter.
an input adapted to be connected to an alternating voltage, an output, a latching switch means having one terminal connected to said input, another terminal connected to said output, and a control terminal adapted to have applied to it a control voltage for latching said switch means in a closed condition to permit current flow between said input and said output during a sub-cycle of said alternating voltage, said switch means switching to an open condition to prevent further current flow therethrough in response to completion of said sub-cycle of said alternating voltage, and a control circuit for actuating said latching switch means into a closed condition during each said sub-cycle including a first source of periodic signals having an output, a first counter for receiving and counting said periodic elect-rical signals from said first source, a second source of periodic electrical signals having an output, a second counter responsive to said second source of periodic signals for receiving and counting said periodic electrical signals from said second source, a comparator for comparing the count in said first counter with the count in said second counter, and means responsive to said comparator for applying a signal to said control terminal to latch said switch means into a conducting condition whenever the count in said first counter equals the count in said second counter.
2. Apparatus according to claim 1, wherein said first counter has an incrementing input and a decrementing input and further comprising means for selectively applying pulses to said incrementing input to cause said latch-ing switch means to assume a closed condition later in said sub-cycle of alternating voltage and to said decrementing input counter for causing said latching switch means to assume a closed condition earlier in said sub-cycle of said alternating voltage.
3. Apparatus according to claim 2 further comprising means for enabling pulses to be applied to one of said incrementing and decrementing inputs of said first counter following a cycle in which pulses are applied to the other of said incrementing and decrementing inputs of said first counter.
4. A variable voltage power supply comprising:
(a) an input adapted to be connected to an alternating voltage source;
(b) an output;
(c) latching switch means having a terminal connected to said input, another terminal connected to said output, and a control terminal adapted to have applied to it a switching signal for latching said switch means into a closed condition to permit current flow between said input and said output during a sub-cycle of said alternating voltage, said switch means switching to an open condition to prevent further current flow there-through in response to completion of said sub-cycle of said alternating voltage; and (d) control means for latching said switch means into a closed condition during each said sub-cycle of said alternating voltage, said control means including:
(1) means for generating a voltage level setting signal:
(2) first counting means having an incrementing input and a decrementing input responsive to a first source of periodic electrical signals, said first counting means including means for storing a count representative of the last selected output voltage level during the last on output state of said power supply;
(3) second counting means responsive to a second source of periodic electrical signals, said second counting means having a reset input responsive to the zero crossings of said alternating voltage;
(4) comparing means for comparing the counts in said first and second counting means, respectively, said comparing means providing when the compared counts are equal said switching signal to said control terminal causing said switch means to latch into a closed condition and permitting current flow between said input and said output; and (5) timing means responsive to said voltage level setting signal for:
a. inhibiting a change in output state of said power supply when the duration of said voltage level setting signal is less than a first predetermined period of time;
b. effecting a change in output state of said power supply when the duration of said voltage level setting signal is greater than said first predetermined period of time and less than a second predetermined period of time; and c. effecting a change in output voltage level of said power supply when the duration of said voltage level setting signal is greater than said second predetermined period of time by selectively enabling one of said incrementing and decrementing inputs to said first counting means.
(a) an input adapted to be connected to an alternating voltage source;
(b) an output;
(c) latching switch means having a terminal connected to said input, another terminal connected to said output, and a control terminal adapted to have applied to it a switching signal for latching said switch means into a closed condition to permit current flow between said input and said output during a sub-cycle of said alternating voltage, said switch means switching to an open condition to prevent further current flow there-through in response to completion of said sub-cycle of said alternating voltage; and (d) control means for latching said switch means into a closed condition during each said sub-cycle of said alternating voltage, said control means including:
(1) means for generating a voltage level setting signal:
(2) first counting means having an incrementing input and a decrementing input responsive to a first source of periodic electrical signals, said first counting means including means for storing a count representative of the last selected output voltage level during the last on output state of said power supply;
(3) second counting means responsive to a second source of periodic electrical signals, said second counting means having a reset input responsive to the zero crossings of said alternating voltage;
(4) comparing means for comparing the counts in said first and second counting means, respectively, said comparing means providing when the compared counts are equal said switching signal to said control terminal causing said switch means to latch into a closed condition and permitting current flow between said input and said output; and (5) timing means responsive to said voltage level setting signal for:
a. inhibiting a change in output state of said power supply when the duration of said voltage level setting signal is less than a first predetermined period of time;
b. effecting a change in output state of said power supply when the duration of said voltage level setting signal is greater than said first predetermined period of time and less than a second predetermined period of time; and c. effecting a change in output voltage level of said power supply when the duration of said voltage level setting signal is greater than said second predetermined period of time by selectively enabling one of said incrementing and decrementing inputs to said first counting means.
5. A variable voltage power supply according to claim 4 wherein said control means further comprises means for reversing the direction in which said first counting means counts each time said voltage level setting signal is interrupted and then reapplied.
6. A variable voltage power supply according to claim 4 or 5, wherein said signal generating means is configured to be user-activated and to provide a voltage level setting signal having a duration which is a function of user activation time.
7. A variable voltage power supply comprising:
(a) an input adapted to be connected to an alternating voltage source;
(b) an output;
(c) latching switch means having a terminal connected to said input, another terminal connected to said output, and a control terminal adapted to have applied to it a switching signal for latching said switch means into a closed condition to permit current flow between said input and said output during a sub-cycle of said alternating voltage, said switch means switching to an open condition to prevent further current flow there-through in response to completion of said sub-cycle of said alternating voltage; and (d) control means for latching said switch means into a closed condition during each said sub-cycle of said alternating voltage, said control means including:
(1) a user-activated voltage level setting signal generator having a control surface input adapted to be touched for a period of time and an output at which a voltage level setting signal appears in response to and during the period of time said control surface is touched;
(2) an n-stage up-down counter having an incrementing input and a decrementing input responsive to a first source of periodic electrical signals, said up-down counter including means for storing a count represent-ative of the last selected output voltage level during the last on output state of said power supply:
(3) an n-stage cyclical counter responsive to a second source of periodic electrical signals, said cyclical counter having a reset input responsive to the output of a zero crossing detector, the input to said zero crossing detector being responsive to said alternating voltage;
(4) an n-stage comparator for comparing the counts in said up-down and cyclical counters, respectively, said comparator providing when the stored count in said up-down counter equals the count in said cyclical counter said switching signal to said control terminal causing said switch means to latch into a closed condition and permitting current flow between said input and said output; and (5) timing means responsive to said voltage level setting signal for:
a. inhibiting a change in output state of said power supply when the duration of said voltage level setting signal is less than a first predetermined period of time;
b. effecting a change in output state of said power supply when the duration of said voltage level setting signal is greater than said first predetermined period of time and less than a second predetermined period of time; and c. effecting a change in output voltage level of said power supply when the duration of said voltage setting signal is greater than said second predetermined period of time and the output state of said power supply is on by selectively enabling one of said incrementing and decrementing inputs to said up-down counter, whereby enabling of said incrementing input causes said switch means to latch into a closed condition later in said sub-cycle of alternating voltage and enabling of said decrementing input causes said switch means to latch into a closed condition earlier in said sub-cycle of alternating voltage.
(a) an input adapted to be connected to an alternating voltage source;
(b) an output;
(c) latching switch means having a terminal connected to said input, another terminal connected to said output, and a control terminal adapted to have applied to it a switching signal for latching said switch means into a closed condition to permit current flow between said input and said output during a sub-cycle of said alternating voltage, said switch means switching to an open condition to prevent further current flow there-through in response to completion of said sub-cycle of said alternating voltage; and (d) control means for latching said switch means into a closed condition during each said sub-cycle of said alternating voltage, said control means including:
(1) a user-activated voltage level setting signal generator having a control surface input adapted to be touched for a period of time and an output at which a voltage level setting signal appears in response to and during the period of time said control surface is touched;
(2) an n-stage up-down counter having an incrementing input and a decrementing input responsive to a first source of periodic electrical signals, said up-down counter including means for storing a count represent-ative of the last selected output voltage level during the last on output state of said power supply:
(3) an n-stage cyclical counter responsive to a second source of periodic electrical signals, said cyclical counter having a reset input responsive to the output of a zero crossing detector, the input to said zero crossing detector being responsive to said alternating voltage;
(4) an n-stage comparator for comparing the counts in said up-down and cyclical counters, respectively, said comparator providing when the stored count in said up-down counter equals the count in said cyclical counter said switching signal to said control terminal causing said switch means to latch into a closed condition and permitting current flow between said input and said output; and (5) timing means responsive to said voltage level setting signal for:
a. inhibiting a change in output state of said power supply when the duration of said voltage level setting signal is less than a first predetermined period of time;
b. effecting a change in output state of said power supply when the duration of said voltage level setting signal is greater than said first predetermined period of time and less than a second predetermined period of time; and c. effecting a change in output voltage level of said power supply when the duration of said voltage setting signal is greater than said second predetermined period of time and the output state of said power supply is on by selectively enabling one of said incrementing and decrementing inputs to said up-down counter, whereby enabling of said incrementing input causes said switch means to latch into a closed condition later in said sub-cycle of alternating voltage and enabling of said decrementing input causes said switch means to latch into a closed condition earlier in said sub-cycle of alternating voltage.
8. A variable voltage power supply according to claim 7, wherein said control means further comprises means for reversing the direction in which said up-down counter counts each time said voltage level setting signal is interrupted and then reapplied.
9. A variable voltage power supply according to claim 8, wherein said control means for selectively applying said switching signal to said control terminal.
10. A variable voltage power supply according to claim 7, 8 or 9, configured to provide 2n discrete output voltage levels wherein said first source of periodic electrical signals comprises a first oscillator having a frequency which is determined by dividing the number of power supply output voltage levels, 2n, by the time desired for the power supply output voltage to cycle between its lowest and highest output voltage levels; and said second source of periodic electrical signals comprises a second oscillator having a frequency which is determined by multiplying the number of power supply output voltage levels, 2n, by twice the frequency of the alternating voltage source.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US183,592 | 1980-08-27 | ||
| US06/183,592 US4396869A (en) | 1979-03-05 | 1980-08-27 | Time responsive variable voltage power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1187546A true CA1187546A (en) | 1985-05-21 |
Family
ID=22673473
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000380105A Expired CA1187546A (en) | 1980-08-27 | 1981-06-18 | Time responsive variable voltage power supply |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1187546A (en) |
-
1981
- 1981-06-18 CA CA000380105A patent/CA1187546A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4396869A (en) | Time responsive variable voltage power supply | |
| CA1239662A (en) | Microcomputer-controlled light switch | |
| US4287468A (en) | Dimmer control system | |
| US3459943A (en) | Silicon controlled rectifier gating circuits with a high frequency triggering voltage and photocells | |
| CA2608413C (en) | Dimmer having a power supply monitoring circuit | |
| US5128595A (en) | Fader for miniature lights | |
| US3710229A (en) | Integrator controlled inverter | |
| US3691404A (en) | Variable duty cycle control circuit | |
| CA1076653A (en) | Multiple-load induction heating cooking apparatus with means for eliminating interference between two or more commutation circuits | |
| CA1187546A (en) | Time responsive variable voltage power supply | |
| US5309084A (en) | Electronic switch with on/off fading | |
| CN106961759B (en) | Light emitting diode device, light dimming system and light dimming method thereof | |
| Dahono et al. | A hysteresis current controller for single-phase full-bridge inverters | |
| JPS56150977A (en) | Voltage type inverter | |
| RU8847U1 (en) | AC VOLTAGE STABILIZER | |
| JPH0431759Y2 (en) | ||
| RU2035767C1 (en) | Power control device | |
| CN107041056A (en) | Incandescent lamp intelligent dimming method | |
| JPS6311061A (en) | Ac power controller | |
| SU1229931A1 (en) | Device for controlling self-excited inverter with tracking | |
| SU1334119A1 (en) | A.c.voltage electric power device | |
| SU1381667A1 (en) | Frequency converter with pulse-duration modulation | |
| SU828351A1 (en) | Single-phase regulator control method | |
| SU1127070A1 (en) | Device for adjusting frequency converter with direct coupling | |
| FR2356992A1 (en) | Power regulator system for electric motor - has series triac controlled by triggering pulses of variable conduction angle and connected to AC supply (NL 3.1.78) |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |