CA1314069C - Light source with gradually changing intensity - Google Patents
Light source with gradually changing intensityInfo
- Publication number
- CA1314069C CA1314069C CA000606263A CA606263A CA1314069C CA 1314069 C CA1314069 C CA 1314069C CA 000606263 A CA000606263 A CA 000606263A CA 606263 A CA606263 A CA 606263A CA 1314069 C CA1314069 C CA 1314069C
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- Prior art keywords
- zero
- light
- time
- circuit
- crossing
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- 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
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
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- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
ABSTRACT
A device and method of awaking a sleeper includes an alarm clock coupled to a control circuit for controlling the power provided to a lamp. After the alarm clock wake-up signal is provided, the light intensity emitted by the lamp slowly, smoothly and gradually increases. The time interval over which the light intensity increases is selectable by the user but will usually be in the range of thirty minutes to an hour. The circuit for increasing the light intensity is designed to ensure that the intensity increase is smooth, especially at the beginning of the wake-up cycle. A photo resistor adjacent an LED is part of a parallel resistive network which lowers the firing angle of a triac to increase the intensity of the light. The LED is biased in the on state to minimize transients as the current through the LED
varies. The use of a parallel resistive network causes the firing angle to change more slowly when the light is very dim then when the light intensity is bright because the human eye is more sensitive to light intensity variations when the background light level is low than when it is high.
A device and method of awaking a sleeper includes an alarm clock coupled to a control circuit for controlling the power provided to a lamp. After the alarm clock wake-up signal is provided, the light intensity emitted by the lamp slowly, smoothly and gradually increases. The time interval over which the light intensity increases is selectable by the user but will usually be in the range of thirty minutes to an hour. The circuit for increasing the light intensity is designed to ensure that the intensity increase is smooth, especially at the beginning of the wake-up cycle. A photo resistor adjacent an LED is part of a parallel resistive network which lowers the firing angle of a triac to increase the intensity of the light. The LED is biased in the on state to minimize transients as the current through the LED
varies. The use of a parallel resistive network causes the firing angle to change more slowly when the light is very dim then when the light intensity is bright because the human eye is more sensitive to light intensity variations when the background light level is low than when it is high.
Description
1 3 1 406~
LIGHT SOURCE WITH ~RADUALLY CX~NGING INTENSITY
This invention relates to circuits for controlling the voltage applied to a light source, and more particularly, to a circuit for gradually varying lo the power applied to a light source to aid in awakening a sleeper.
Numerous devices and methods for awakening a person from sleep are presently in use~ Among these devices are included clock radios, alarm clocks, and other devices which emit a loud sound at a preselected time to awaken the sleeper. Another method, frPquently used by a third person who desires to awaken a sleeper, is to immediately turn on the main lights in the room.
The rapid change from dark to light shining above the sleeping person's face awakens the sleeper, even though his eyes are clo~ed.
The methods of awakening a sleeper mentioned above do so with a sudden jolt to the sleeper. The sudden loud ring of a bell, buzz of an electric clock, or ~lash of light shock the brain and body of the sleeper from whatever state of sleep he is in into sudden wakefulness. The sudden shock to the sleeping body, while designed to awaken the sleeper, has detrimental side effects. Many people, immediately upon being so awakened, are very irritable and angry. There have been reported instances of an otherwise mild-mannered and gentle pexson, upon being suddenly awakened, reacting violently, such as by breaking the alarm clock, throwing an object, refusing to talk for the next twenty minutes, or the like. If a bright light ::
LIGHT SOURCE WITH ~RADUALLY CX~NGING INTENSITY
This invention relates to circuits for controlling the voltage applied to a light source, and more particularly, to a circuit for gradually varying lo the power applied to a light source to aid in awakening a sleeper.
Numerous devices and methods for awakening a person from sleep are presently in use~ Among these devices are included clock radios, alarm clocks, and other devices which emit a loud sound at a preselected time to awaken the sleeper. Another method, frPquently used by a third person who desires to awaken a sleeper, is to immediately turn on the main lights in the room.
The rapid change from dark to light shining above the sleeping person's face awakens the sleeper, even though his eyes are clo~ed.
The methods of awakening a sleeper mentioned above do so with a sudden jolt to the sleeper. The sudden loud ring of a bell, buzz of an electric clock, or ~lash of light shock the brain and body of the sleeper from whatever state of sleep he is in into sudden wakefulness. The sudden shock to the sleeping body, while designed to awaken the sleeper, has detrimental side effects. Many people, immediately upon being so awakened, are very irritable and angry. There have been reported instances of an otherwise mild-mannered and gentle pexson, upon being suddenly awakened, reacting violently, such as by breaking the alarm clock, throwing an object, refusing to talk for the next twenty minutes, or the like. If a bright light ::
2 131~06q is used in place of an audio alarm to awaken the sleeper, the sudden change from dark to light not only shocks the sleeper's body but also causes the additional effeGt of temporary blindness and significant discomfort for the sleeper until his eyes have adjusted.
Recent electronic alarm clocks provide a snooze button that the sleeper may press after the first sudden jolt to give him ten to twenty minutes to fall back asleep or rest before receiving a second jolt or being forced to rise. Some alarms permit the user to select a radio station which plays pleasing music, the music being turned on at the time of the alarm to awaken the sleeper. The proposed solutions are somewhat less painful than a loud buzz or bright light but ~till do not solve the problem of shocking the brain and body by suddenly changing the sleeping environment to awaken the sleeper at a preselected time.
The detrimental effects of suddenly awaksning a sleeper from any given state of sleep are not fully under stood. Some effects, such as irritability, are immediately apparent, but the effect on the p~rformance of the body and brain throughout the day is not clear.
In some stages of sleep, the sleeper~ 9 respiratory rate, heart rate, and other body functions are very slow. In other stages of slaep, such as REM sleep ~where dreaming occurs) or in light sleep, the body functions are at different rates than in deep sleep~ A sudden jolt from one of the different stages of sleep produces different effects on the body. A person awakened from a deep sleep state may be much more irritable than one awakened from a light sleep state. Work performance throughout the morning and after noon hours may remain significantly affected by the sudden jolt from one type or another of sleep.
Recent studies have indicated that the human body contains its own internal biological clock. The biological clocks adjust to changes in the environment.
Recent electronic alarm clocks provide a snooze button that the sleeper may press after the first sudden jolt to give him ten to twenty minutes to fall back asleep or rest before receiving a second jolt or being forced to rise. Some alarms permit the user to select a radio station which plays pleasing music, the music being turned on at the time of the alarm to awaken the sleeper. The proposed solutions are somewhat less painful than a loud buzz or bright light but ~till do not solve the problem of shocking the brain and body by suddenly changing the sleeping environment to awaken the sleeper at a preselected time.
The detrimental effects of suddenly awaksning a sleeper from any given state of sleep are not fully under stood. Some effects, such as irritability, are immediately apparent, but the effect on the p~rformance of the body and brain throughout the day is not clear.
In some stages of sleep, the sleeper~ 9 respiratory rate, heart rate, and other body functions are very slow. In other stages of slaep, such as REM sleep ~where dreaming occurs) or in light sleep, the body functions are at different rates than in deep sleep~ A sudden jolt from one of the different stages of sleep produces different effects on the body. A person awakened from a deep sleep state may be much more irritable than one awakened from a light sleep state. Work performance throughout the morning and after noon hours may remain significantly affected by the sudden jolt from one type or another of sleep.
Recent studies have indicated that the human body contains its own internal biological clock. The biological clocks adjust to changes in the environment.
3 ~314069 When dayc are long in the summer and short in the winter, the biological clocks automatically readjust.
The body's clock runs on what i5 known as a "circadian rhythm," in synchronism with apparent movement of the sun.
Our bodies, like most living things, adjust to changes in light. At the base of the brain, a cluster o~ nerve cells, the suprachiasmatic nuclei (SCN), monitor light reaching the body. The SCN not only distinguish intensity changes, as from night to day, but also distinguish and respond to changes in the length of day and changes in light intensity at different times of the day, even though the changeæ in light intensity may be so small as not to be percep~ible to the conscious mind. This bundle of nexve cells, the SCN, sends out signals to the major control centers in the body that control, among other things, sleeping, body chemistry throughout the day, growth and sexuality. While not prior art to the present invention, an article in the December 1987 National Geographic titled "What is this thing called sleep?" by Michael E. Long, recognizes the body's sleep states and the ability to alter the body's clock using light. According to the article, one Harvard researcher, Dr. Charles Czeisler, has demonstrated that by using bright light, a person's circadian rhythms and internal biological clock can be shifted dramatically. The article, on page 803, states that Dr. Czeisler has positioned persons in front of lights mimicking sunrise or sunset to reset the bioloyical circadian clock of a person.
Nature provides a gradual and smooth increase of ambient light at the beginning of each day with the rising o~ the sun. The ambient liyht outside begins to very gradually increase from the darkness of night to the light of sunrise over a one to one-half hour period just prior to sunrise. The amount of time between when the sky begins to lighten and when the sun actually
The body's clock runs on what i5 known as a "circadian rhythm," in synchronism with apparent movement of the sun.
Our bodies, like most living things, adjust to changes in light. At the base of the brain, a cluster o~ nerve cells, the suprachiasmatic nuclei (SCN), monitor light reaching the body. The SCN not only distinguish intensity changes, as from night to day, but also distinguish and respond to changes in the length of day and changes in light intensity at different times of the day, even though the changeæ in light intensity may be so small as not to be percep~ible to the conscious mind. This bundle of nexve cells, the SCN, sends out signals to the major control centers in the body that control, among other things, sleeping, body chemistry throughout the day, growth and sexuality. While not prior art to the present invention, an article in the December 1987 National Geographic titled "What is this thing called sleep?" by Michael E. Long, recognizes the body's sleep states and the ability to alter the body's clock using light. According to the article, one Harvard researcher, Dr. Charles Czeisler, has demonstrated that by using bright light, a person's circadian rhythms and internal biological clock can be shifted dramatically. The article, on page 803, states that Dr. Czeisler has positioned persons in front of lights mimicking sunrise or sunset to reset the bioloyical circadian clock of a person.
Nature provides a gradual and smooth increase of ambient light at the beginning of each day with the rising o~ the sun. The ambient liyht outside begins to very gradually increase from the darkness of night to the light of sunrise over a one to one-half hour period just prior to sunrise. The amount of time between when the sky begins to lighten and when the sun actually
4 1 31 4069 rises depends upon the distance from the equator: the greater the distance from the equator, the longer the time between when the sky begins to lighten and the actual sunrise time. Similarly, after the sun has set, the sky remains light or a period of time and gradually darkens to the night condition.
The biological clock of a person operates, when possible, in synchronism with the sunrise and sunset at his position on the earth. When the biological clock is not in synchronism with their working day and the local sunrise and sun~et, mental ability and body performance are significantly lowered.
Recent studies of people suffering jet lag and of people working swing shift have demonstrated that mental and physical performance is impaired because their internal biological clock is not synchronized with their work day.
Unfortunately, many people in today's world are not able to take advantage of the natural light change at the start and end of each day. Many people must awaken and fall asleep on a schedule different from the rising and the setting of the ~un. For example, many people must be awakened before the sun rises in order to prepare for work and arrive at work on time.
Other people, such as those working a swing shift or living in a northern latitude in the summer, desire to sleep well past the sunrise time and be awakened later to prepare for and start their work day. Similarly, many people desire to remain awake after the sun has set and go to sleep on their own schedule, for example, after wat~hing a particular television program or the like. The schedule at which each person awakens and goes to sleep each day may be significantly differsnt from the sunxise and sunset times of each day.
1 31 ~06q It is therefore an object of this invention to provide a novel apparatus for varying the brightness of a light that causes a gradual and smooth change in theperceived light intensity.
According to the present invention there is provided an apparatus for varying the brightness of a light wh;ch is adapted to be powered by an AC power supply having æro-crossings, in a nonlinear power level as a function of time, comprising:
a circuit for providing power to said light from the AC power supply;
a zero-crossing sensor means for sensing each zero-crossing of said AC power supply and outputting a zero-crossing signal at each of said æro-crossings;
a precision timer coupled to the output of said zero-crossing sensor and receiving said zero-crossing signals, said precision timer outputting an oscillating frequency signal h~ving a plurality of zero-crossing points in between each zero-crossing of said ~C power supply and at least one of said oscillator zero-crossings occurring simultaneously with said AC power supply zero-crossings;
an electric circuit that generates a trigger pulse at a selected time after said AC
signal zero-crossing, said selected time being variable from a first time after said zero-crossing to a second time after said zero-crossing, said second time occurring more closely after said AC zero-crossing than said first time occurs after said AC zero-crossing, said selected time gradually varying from said first time to said second time after an input si~gnal goes high to cause the AC power supply to increase in a nonlinear power level as a function of time; and a switching circuit coupled to said electric circuit for causing a switch to turn on and provide power to said light ~rom said trigger pulse output going high until said AC power supply passes through a subsequent zero-crossing to thus control the intensity of said light based on said selected time of said trigger output line going high.
5a 1 3 1 4069 Preferably, an electrical pulse, such as from an alarm clock, begins the operation of the circuit at a preselected time. The intensity control circuit gradually and smoothly increases the RMS voltage applied to the lamp ~rom a low voltage level towards the line voltage level.
The intensity control circuit includ~s a capacitor in an RC circuit which is charging towards a final voltage. The voltage ~upply applied to the RC
circuit is a eonstant value with isolation to minimize th~ noise to ensure that the ~oltage level of the charging capacitor increases ~moothly. The output voltage of the charging capacitor is coupled to an operational amplifier. The output of the operational amplifier, having the charging capacitor as its input, is coupled to an operational amplifi~r having a negative gain. The output o~ the negative gain operational ,~5 1 31 406q amplifier is coupled to an "optocoupler" having an LED
adjacent a photoresistor. The negative gain amplifier is biased in the ~'on" itate, drawing current through the LED at all times. By having the LED in the "on"
position, the change in intensity in the lamp is very gradual, from a very low-intensity level to the high intensity level.
The photoresistor is part of a parallel resistive network, the network being in series with a triac. The value of the resistance network is selected to ensure that the RMS voltage remains below the level at which the lamp emits light until after the capacitor is past 6 percent of the time of the RC time constant.
The firing angle of the triac v~ries gradually and ~moothly to vary the RMS voltage applied to the light source from a 2ero-voltage level to the ~aximum available voltage levPl, such as line voltage.
Embodiments of the present inventio~ will now be described more fully with reference to the accompanying drawings in which:
Figure 1 is a block diagram of the electrical components of the invention.
Figures 2A and 2 are a circuit diagram of the components of Fi~ure 1.
Figure 3 is a wind~w diagram plotting numerou~
parameters Df the circuit of Figures 2 and 2A on the same graph.
Figure 4 is a ~chematic of an ~lterna~iv~
embodiment fQr drivin~ the variable voltage on the load.
Figure 5 is a ~chematic of a microprocessor controller for the alarm.
Figures 6-8 are schematics of ircuits coupled to the microprocessor of Figure 5.
Figure 9 is a schematic of the LCD display coupled to the microprocessor.
Ji ; ~.~,i .
7 1 31 406q The sensitivity of the eyes to light and variations in light intensity depends upon the state of the eyes, the background light, the wavelength, and ~ther factors. When the eyes have become adjusted to the dark, after a~out 30 minutes, the eye is at least 10,000 times more sensitive to light than during the day, when the eyes are not dark-adapted. When ths eye is dark-adapted, not only does the dilation of the eye change, the chemistry of the eye changes to make it much more sensitive to light and to changes in light intensity. A chemical called "rhodopsinl' is present in significant quantities in dark-adapted eyes but is absent in light-adapted eyesv The dark-adapted eyes can sanse even minute changes in light intensity, even below the level of consciousness of the person, when the background light levels are very low.
When the eye lids are closed and the person is asleep, a very faint light can be sensed by the dark adapted eyes. Signals are trans~erred to the brain and nerve cluster at the base of the brain, the suprachiasmatic nuclei, to began to slowly and gently change the body chemistry to prepare the body to wake up. As the light level increases, very small changes in intensity are sensed by the eye, because it is still dark-adapted, and the rate of change in the body's chemistry and internal wake-up clock can adjust to the gradually increasing intensity of the light.
Because of the sensitivity of dark-adapted eyes to variations in light intensity, a very smooth change in light level is preferred. If the increase in light intensity has step functions, jagged edges, or other irregularities, even very small irregularities, the eyes, being very sensitive, will recognize that the increase is not gradual nor constant and the waking process will be less pl~asant then it could otherwise be. The eye is most sensitive to changes in light 8 1 31 406q intensity at the ~ery start o~ the waking process, when the eye is completely dark-adapted and the background light levels are low. Therefore, it is most important that the increa~e in light intensity be very smooth~ and preferably slow, at the very beginning of the wake-up cycle. The circuit having the amplifier and LED biased into the "on" condition prior to receiving the wake up signal ensures that the increase will be very smooth and gradual, even ~rom the very beginning.
The circuit for directly controlling the light intensity of a lamp smoothly, gradually and automatically, similar to the rising or setting of the sun, is illustrated in block diagram form in Figure 1.
The circuit includes an input into a ~uf~er circuit 12 from an alarm clock 10. The alarm clock provides a wake-up signal at a preselected time, as determined by the user. Any standard alarm clock circuit may be used to provide the signal, as is well known in the industry.
The bu~Per circuit 12, a~ter appropriate ~0 amplification and filtering, provides a signal to charging circuit 14 to begin varying the voltage applied to a lamp 26. The charging circuit is coupled through an amplifier 16 to the LED of an optocoupler 18.
Varying the intensity of the LED in optocoupler 18 causes the power provided to lamp 26 to be varied. The power is varied by changing the ~iring of the angle of a triac in power supply circuit 20 coupled to line voltage source 24. The particular voltages and power required for the respective circuits are pxovided by DC power supply 22, which receives input power from line voltage power supply 24. The power provided to the lamp 26 may be directly controlled, either decreased or increased or preset to a selected level, by the manual circuit 28 : coupled to charging circuit 14.
A detailed circuit diagram of the clock circuit of Figure 1 is illustrated in Figures 2A and 2.
An alarm clock circuit 10 is coupled to an alarm node !3 1 3 1 4 0 1~ 9 input 30 of the buffer circuit 12. The buffer circuit 12 inclu~es, in one embodiment, an amplifier 32 coupled through a capacitor 34 to alarm circuit input 30~ The gain of the amplifier 32 is determined by the value of resistors R24 and R25, as is well known in the art. The output of the amplifier ~2 is coupled, through a capacitor 36, to the input 38 of the charging circuit ~4~ In an alternative embodiment, Option 5, th~ huffer circuit 12 includes a light-emitting diode 35 adjacent a light-sensitive transistor 37 coupled to the input 38 for providing the signal ~rom the alarm input 30 to the charging circuit 14.
The input 38 to the charging circuit 14 is coupled to the set input of RS flip-flop 40. The filter capacitor, C10, at the triggering input 38 filters transients tv prevent false triggering which may be caused by power line surges, glitches, or other transients. Resistors R22 and R23 bias the set input to flip-flop 40 at half of the power supply voltage, Va, for noise rejection. The output, node f~gj, of the flip-flop 40 is pulled up to a given voltage level, usually the level of the positive power supply, Va, on the negative-going pul~e at the input 38 of node f(f~.
The output, Q, of RS flip-flop 40 is coupled through 25 resistor network R17 and R16 to zener diode 42. The : voltage of the output of the flip~lop 40 i5 reduced in node f~h) by the resistive network R17 and R16 to a value within the range of the most stable operational range of the amplifier 48 Por the time period of particular concern. In a preferred embodiment, this value is approximately 4 volts, though any other suitable value may be used. A zener diode 42 is selected having a very high reverse impedance to minimize the leakage through it from capacitor 44.
The time constant of the RC circuit formed by potentiometer 46 and capacitor 44 is given by the equation:
lo 1 3 1 406q T.C. = RC (1) where T.C. is the time constant of the RC circuit.
Potentiometer 46, Yr2, is salected to be relatively large to provide a long-time constant and a slow charging rate o~ the timing capacitor 44. The resistance of potentiometer 46 is manually adjustable by the user at control 43 to set the time constant at any de~ired value, generally from as low as two minutes to greater than ten hours.
The voltage of the timing capacitor 44 is coupled to the input of amplifier 48. The amplifier 48 is selected to have an extremely high input impedance, for example, over a billion ohms or greater, to minimiz discharge through it of the timing capacitor 44. An FET
input opamp is suitable for amplifier 48. The ampli~ier 48 operates as an isolating buffer, similar to an emitter follower with a gain of one. The output at node ftj) of amplifier 48 sxactly follows the input from the timing capacitor and is equal to it.
The output f(j) from the amplifier 48 provides the output from the charging circuit 14 and the input into the amplifier circuit 16. The amplifier circuit 16 includes, in the preferred embodiment, an inverting ampli~ier 50 having a negative gain. The output of amplifier 50 to node f(l) is biased to a negative startinq point by a constant negative-bia~ed voltage at node f(k). The input from node f(j3 to amplifier 50 is to the inverting input and therefore inverts the signal from the output of operational amplifier 48. The gain of operational amplifier 50 is determined by the ~ equation:
: R10 Gain = - (2) ~11 The gain is selected to be a value less than one by makinq Rll greater than R10.
~1 1 3 1 ~069 The gain o~ amplifier 50 i5 made negative to ensure that the operation i~ stable. By making the gain negative, many advantages are achie~ed in providing a more stable output. For example, the amplifier operates in the middle o~ it~ rated rang~ at all times and does not operate at either end of its rated range, where the output is less stable. Further, variations in the input, including any noise, are reducad rather than amplified~ This makes the output more smooth and stable. The circuit providing power to the LED need not include a negative gain amplifier so long as the circuit provides a sufficiently smooth and stable output. It has been found that use of a capacitor followed by a negative gain operational amplifier is one way to achieve a su~ficiently smooth, ~table output.
A constant~ negative-biased voltage is provided at node f(k), as determined by the equation:
f(k) = R13 + R12 x Vc (3) The constant, negative-biased voltage f(k) provides a negative voltage base level at the output node f(l~ of operational amplifier 50, while the input from node ~(j) determines the additional negativ~ swing at ~he output, giving a total output f(l), which is equal to the amplified combination of the voltage on the timing capacitor f~i) and the negative-bias~d voltage f(k).
The voltage on the node f(l) is given by the equation:
R13 x Vc x (R10 ~ Rll) R10 ~13 + R12 f(l) = f(i) x ~ Rll (4) (Part A) (Part B) 1~ 1 31 4069 When the capacitor is not charging, the voltage of node f(i) is zero volts and Part A of the equation goes to æero, resulting in the voltage at node f(l) on the output of operational amplifier 50 being determined solely by the constant negative-biased voltag~, as given by the Part^B of the equation. In the preferred embodiment, the constant negative-biased voltage at node f(l) is 1.5 volts, based on a selection of an amplifier havin~ very stable operation in that range and to avoid transient responses.
The output of amplifier 50 is coupled to the LED 52 of the optocoupler circuit 18. The LED 52 is held in the "on" state at all times by the output from amplifier 50. The constant, negative-biased voltage of the amplifier 50 is selected to provide an output to the LED 52 which holds it in the "on" state in a range of stable operation. Generally, this range o~ operation will be just slightly above the voltage at which the LED
begins to conduct and is fully "on.'^ It is selected to be above the voltage at which the LED switches "on" to ensure that discontinuities, glitches or transients often occurring with an LED switching from "off" to "on~
are avoided.
The change in current through the LED 52 is directly controlled by the charging capacitor 44. Ths voltage on the charging capacitor 44 at node f(i) is given by the equation:
f(i) = tf~h) x (1 e(t/T C )~]
Where t is the elapsed time in minutes since the alarm signal set RS flip~flop 40 to start the charging of the capacitor and T.C. is the time constant of the RC
circuit in minutes.
The optocoupler cell photoresistor 54 is part of a parallel with a resistor network 56 of lamp pow~r circuit 20, as shown in Figure 2. R~sistor R2 and 13 13~4069 photoresistor 54 form parallel resistance network 56.
The parallel resistive network 5~ is coupled in series with resistors R1 and R3 to the gate o~ the triac 58.
The total resistance of the parallel resistive network 56, RNt, is given by the equation:
1 ~ x R2 . = . (6) 1 1 ~ + R2 _ ~ _ ~2 The optocell 54 is selected to have a very high resistance, ~, relative to resistor R2 when the LED is biased in the just slightly "on" conditio~ by the output of amplifier 50. With the LED just slightly "on," the resistance, value RNt~ of the parallel resistive network 56 will be approximately egual to the resistance of R2, as can be seen from Equation 6, because ~ is so much higher than R2. The series resistance of Rl, R2 and R3 is selected to ensure the firing angle of the triac 58 is so high that the lamp does not emit light.
;The value of ~, with the LED in the slightly "on" state, is in the range of 100 to 10,000 times greater than R2. The exact ratio selected depends on the rate at which the resistance is desired to be lowered in response to the gradually increasing brightness of the LED 52. In a pre~erred embodiment, R2 :is 56 kohms and ~ varies from above 1 Mohms to :~30 approximately 300 ohm Because ~ is so much greater ~:than R2 when the lamp begins to emit light, linear changes in ~ effect very, very small, nonlinear changes in RNt, and thus increase the brightness of lamp 26 only a very small amount. For example, when ~ is much greater than R2, if ~ decreases 1000 percent, the network resiatance, RNtt will decrease less than percent. As ~, starting at a differ~nt value is reduced, ~or example, ano~her 1000 percent, this may decrease RNt by about 10 percent. As Rp becomes almost equal to R2, further changes in ~ produce a greater percentage change in RNt. For example, a 10% change in may produce a 5% change in RNt. As Rp continues to go lower~ so as to be much lower than ~2, the value of Rp becomes controlling and the network resistance RNt will be approximately equal to ~ and will follow it almost exactly. The exact rate of change can be seen by plotting ~ versus RNt based on Equation 6.
The use of a single resistor in a parallel resistive network to control the firing angle of the triac causes the intensity variation of the light to be very, very gradual and slow at the low light levels, but the rate of intensity variations to be greater at higher light levels. A very gradual increase at a low light intensity level is preferred for this invention because the human eye is much more sensitive to variations at low light intensities with low background light than to variations of high light intensities with a high background light level, as is well known in the art.
The dark-adapted eye of the sleeping person is particularly sensitive to changes of intensity at low light levels. The use of a parallel resistive network and selection of R2 and ~ provide that changes in light intensity occur ~ery slowly at low light levels and more rapidly at high light levels for awakening a sleeping person. To the eye of the sleeping person however, the light intensity increase is gradual and steady because the eye becomes less sensitive to changes in intensity as the light increases, as discussed in Patent No.
3,684,919 to Cramer.
~ Additional parallel reslstors or parallel photoresistors ; adjacent the LED may be us d if desired~
As the resistance of the parallel resistive network, RNt, decreases, the total series resistance decreases, thus lowering the firing angle of the triac 58. As the firing angle of the triac 58 is lowered, the RMS voltage provided to lamp 26 increases accordingly.
! i Ji The use of an optocoupler circuit isolates the lamp power supply circuit 20 from the remainder of the circuit~, allowing the power ~upply 22 to be transformerless. The RMS voltage provided by the lamp powar supply circuit 20, including the triac 58, smoothly and gradually increases. ~he net resistance of the series resistors Rl, RNt and R3 determine at what angle the triac 58 begins to ~ire. The combination of capacitors C1 and C2, in parallel with rasistor R3, acts as a ~ilter to prevent false firing of the triac 58, which may be caused by transients, harmonic response or the like. The combination oE inductor Ll and capacitor C3 filter out power line transients and the like caused by the firing of the triac or from the power line. A
fuse 60 is provided to ensure that the circuit is not damaged due to overloading.
The power supply 22 provides the DC voltages for circuit operation. A positive voltage, Va, is provided to the respective circuits, as indicated in Figure 2A. A neqative voltage, Vc, which is the opposite of Va, is provided to the circuitry, as shown in Figure 2A. Zener diodes D2 and D3 and capacitors C4 and C5 are selected to ensure that Va iæ always equal to negative Vc. A common voltage source (com) is provided in the node between capacitor C4 and C5 in the power supply 22, a~ shown in Figure 2. The common (com) supplies the reference ~or all other supply voltages and acts as system ground. The zener diode D4 is a backup diode and prevents possible damage to the circuits if one of the zener diodes, D2 or D3, fails. Diodes D5 and D6 rectify the input line voltage across f(a). Diode D5 is provided as a backup diode in the event diode DS
fails.
The lamp 26 is coupled to the lamp power supply circuit 20 using any one of several known wiring patterns. In Option 1, the lamp 26 is wired as a main light in a room~ the light being in the ceiling and the 16 1 31 ~ 069 switch being located on the wall. The master light in the room, such as the one mounted in the ceiling, is generally positioned sufficient near the sleeper to awaken him. For Option 1, the input power is provided from one wire going to the lamp, the lamp being in series with the various circuits of this invention. The power provided to the circuit will be lowered by the voltage drop across the lamp 26 whan the lamp is coupled using the wiring pattern of Option 1. For Option 1, regulation of the power supply is provided by the series regulator circuit combination of Q1, R5, R6 and D7; all of which dissipate virtually all of the power ~upply's heat. R5 is selected to be large enough to limit the current of Ql to a safe value. D7 limits the peak base voltage of Q1 to a saPe value. C6 filters out transients from the power supply to prevent false triggering of the flip-flop 40 in the charging circuit 14. The alternative circuit having transistor Q1 is required to regulate over a relatively large range, from about 105 volts RMS to approximately 20 volts RMS, because, as the lamp increases in brightness, the voltage f(a) provided to the power circuit is correspondingly decreasing.
The lamp 26 may alternatively b~ connected as shown in Option 2 of Figure 2. In Option 2, a standard house plug is provided for the circuits of this invention to be plugged into any desired wall outlet. A
industry standard-sized wall outlet 26 is provided into which a lamp (not shown) may be plugged. The power provided to outlet 26 for the lamp follows the power curves described herein to permit the power to the lamp to be varied as described.
A power supply for an ~larm clsck may be provided by Vb from the power supply, a~ illustrated by an alternative embodiment of Option 3, if desired. R7 and R8 perform a divider for clock supply voltage, which is filtered by C7.
17 131~,069 The manual switch control 28 provides manual control of the light intensity to a selected value.
Switches are provided to permit the user to manually select a light inten6ity value or to move the light intensity up or down. One switch, SW1, selectively couples the charging capacitor to ground through a bleed resistor R20 to discharge the circuit and turn the lamp "off." The discharging of capacitor 44 through bleed resistor R20 can be stopped at any time by the user to hold the intensity of lamp 26 at any desired level. The leakage of capacitor 44 is sufficiently low and the resistance presented by zener diode 42 and amplifier ~8 are suffici~ntly high that the intensity of the lamp 26 will remain constant ~or several hours, or even days.
Another switch, SW2, may be depressed to gradually manually increase the light intensity to any desired level by manually charginy the timing capacitor by directly coupling the timing capacitor to the voltage supply Va through resistor R18, having a significantly lower value than potentiometer 46.
The operation of the circuit can be understood by viewing the relative voltages at each of the nodes and the relationship between them, as shown in Figure 3.
At a time tl, a start pulse is provided by an alarm clock or other external circuit to begin the operation ~, of the circuit. A negative-going pulse to the input of the RS flip-flop 40 causes the RS flip-flop to come "on"
at a time t2 and remain on until the circuit is reset.
As shown in Figure 3, the charging capacitor 44 begins to charge from a low voltage level at time t2, approaching a maximum voltage as determined by the resistive network R17 and R16. The time taken for the capacitor voltage to reach the final voltage is : determined by the time constant, as previously described. After 6~2/3 percent of the time constant has passed, the voltage at the charging capacitor in node f(i3 reaches a level at which the lamp 26 begins to emit 18 1 31 ~ra69 a faint glow, visible to the dark-adapted eye, as indicated by time t3 in Figure 3. The voltage on the charging capacitor continues to rise in a gradual, smooth and linear fashion from t3 to t4. The time t4 is 20~ of the time constant of the RC circuit. The voltage level on the capacitor, to which node f(i~ is charged, will be significantly slower in charging after 20 percent of the time constant has elapsed, as the voltage increase on the capacitor approaches the final voltage f(h). However, for the time period from t3 to t4, the voltage rise in node f(i) is extremely smooth, gradual and generally linear. The tima period from t3 to t4 represents the time period in which the lamp first begins to glow in a manner perceptible to the most sensitive eye at time t3 until the lamp is sufficiently bright at time t4 that further increases in lamp voltage do not result in intensity changes detectable by the human eye.
The output of operational amplifier 50 is illustrated in Figure 3 as the voltage at node f(l)~
The voltage is biased to a negative value, such as 1.5 volts, by the resistive network R13 and R12, as amplified by the operational amplifier. The operational amplifier 50 is held in the "on" position and in a stable operating range at all times to minimize the occurrence of transients associated with the turning "on" of the amplifier, LED and the like. Further~ the LED is turned "on" at all times, previous to the capacitor 44 being charged, to ensure that transients associated with the switching "on" of the LED do not affect the intensity of the lamp 26.
The beginning of the charging of the capacitor 44 represents a zone of safety below which the lamp voltage f(n) remains so low that the lamp is in the "off" condition. The gain of amplifier 50, value of resistors R3, R2 and Rl, and the operating characteristics of photoresistor 54 and triac 58 are 19 131~V69 salected to ensure that the lamp does not emit light during the initial charging o~ the timing capacitor 44.
This zone is generally selected to be at least 5 percent o~ the time constant of the voltage rise at the node f(i) and, in a preferred embodiment, is 6^2~3 percent o~
the time constant of the rise in voltage at f(i). This safety zone prevents the lamp ~rom lighting during the initial charging state of the capacitor 44. This ensures that transients associated with the beginning of the charging of the capacitor do not affect the changes in light intensity o~ the lamp 26. When the voltage at node f(i) reaches the level of approximately 6~2/3 percent o~ the time constant, the output of the amplifier 48 drives the output of th2 amplifier 50 in node f(l), sufficiently negative to lower the combined resistance of the optocoupler resistor 54 and R2 to a value at which the firing angle of the triac provides suf~icient power to the lamp that the lamp emits a faint glow, a very low-intensity light. The glow is sufficiently faint that in full day light or in a room of high background light, the human eye does not datect the lamp gl~wing. However, after th~ person has been asleep for many hours, the dark-adapted eye is lO,OOO
times more sensitive to light than during the normal waking conditions. The eye of the sleeping person, therefore, detects a faint glow co~ing from lamp 26 and transmits this information to the brain of the sleeper, even though the voltage on the lamp 26 is extremely low, for example, 6 to 8 volts RMS.
The voltage on the lamp f(n~ rises from zero volts RMS towards line voltage, ~or example, 120 volts RMS at time t4. The voltage across the lamp will grad~ally and smoothly increase according to the equations as provided herein towards full li~e voltage for the lamp, which is approximately 120 volts in Option 2 and approximately 105 vo~ts in Option ~ter time t4, t~e li~ht i~te~si~y ~ay contin~e to ,inçr~~
1 31 4 06 q measured by instruments, if desired, but the light is sufficiently bright that further increases in brightness of the lamp are not detectable by the human eye.
Generally, the time from t3 to t4 will be in the range of 30 minutes to 45 minutes. The user may ~1ect the time from t3 to t4 to be significantly greater than an hour or as low as 2 minuteg, depending on a desired time to wake up by varying the value of p~tenti~meter 46, using a manual adjustment knob 43.
one o~ the ~ignificant advantages of this invention is that each of the components operates within stable operational windows when the lamp 26 is emitting light. The capacitor 44 is selected to have very stable and linear operation as it charges from zero to a voltage just above the start of the charging curve to the maximum voltage provided at node f(h). A capacitor having sta~le operation in this voltage range will often have a top operating range signifi~antly higher than this voltage.
Amplifiers 48 nd 50 are selected which have very stable output characteristics over their range of operation. Usually the amplifiers will be operated in the middle of their rated range to ensure that the operation is stable. For example, the output of amplifier 50 varies from a low of 1.5 volts to a high of 1.75 volts corresponding to the lamp 26 being off to the lamp 26 being sufficiently bright that further increa~es in intensity are not d~tectable. While this is a very small voltage swing, amplifier 50 is very stable over this range and is thus suitable for varying the current drawn through LED 52. Similarly, LED 52 is held "on" at all times to ensure that its operation window is within the range of stable operation of the LED. Each of the components and the respective voltages at sach node are selected to ensure that each device is operating in a stable window of operation during the time period from t3 to t4 when the intensity in lamp 26 is varying to provide a very smooth and gradual intensity curve to gently and smoothly awaken the sleeper. It is not required that the amplifier 50 and LED 52 be on at all times to ensure stable operation of the circuit. One method to ensure that tha circuit elements are in stable operation from t3 to t~ is to have them "ON" prior to t3. One way to ensure that the elements are l'0N" prior to t3 is to bias them "ON" at all times; but other techniques may also be used.
Figure 3 illustrates the operational windows by including several parameters, plotted along a common time line but having significantly different values.
The graph of Figure 3 has the common time line of the time constant of the RC circuit formed by potentiometer 46 and capacitor 44. The time line increments are based upon the percentage of the time constant of the RC
circuit, rather than on real time in seconds. The charge on the timing capacitor f(i) is represented by the curve f(i), as indicated, showing a safety margin of 6^2/3 percent of the time constant of the RC circuit, prior to the remaining elements in the circuit permitting the voltage to be sufficient to cause the lamp to begin to glow in a manner perceptible to the dark accustomed eye. The lamp voltage f(n) is shown as a function of the time constant and will reach approximately 90 percent of the line voltage after 20 percent of the time constant of the charging capacitor has passed. The firing angle resistance of the triac 58 varies, as shown in Equation 6, in a smooth pattern, as the voltage on the timing capacitor increases. The output of the amplifier 50, f(l), the driving voltage of the LED 52, is a negative voltage and becomes more negative as the timing capacitor increases. The LED 52 is always operated in the stable range of operation to ensure that all changes in the intensity of the light are gradual and smooth. In the upper range of operation, after 20 percent of the time constant has 22 13140~'~9 pas ed, at relatively high voltages, the lamp voltage may include some transients no occurring during the low voltage operation of the lamp but these do not interfere with the basic operation of ths invention. Such transients are permissible because the lamp is sufficiently bright that the human eye cannot detect changes in the brightness of a light which is already extremely bright.
The user can be gently and comfortably awakened using the lamp 26 of this invention as his alarm clock. The brain of the sleeper receives the signals from the eye that the room is beginning to brighten. As the light continues to very slowly increase in intensity, the rate of increase is also sensed by the brain. The brain sends out the appropriate control signals to start changes in the body chemistry o~ the sleeper. Even though the person is sleeping and may be in a very deep sleep at the time the light first emits a faint glow, the gradual increase of light over a one-half hour to one hour period brings the body functions slowly up to the waking state. By ensuring that the initial light intensity is very low and that all increases are very gradual and very smooth, especially at the beginning of the wake-up cycle, the body of the user is very gently and comfortably awakened. The jolts and sudden changes oP state in the body of the sleeper caused by the prior àrt devices are thus avoided. Upon awakening, u~ually when the light is quite bright, the sleeper's body chemistry has adjusted to be prepared for the waking state. The user feels refreshed and ready to become active, rather than being irritable, grumpy and nonfunctional for a period of time. Some results of experiments indicate that perPormance throughout the day is significantly improved when the person has been awakened using the device and method of this invention.
23 l 31 4069 The rate o~ light increase is fully selectable by the user. The user may lower the resistance of potentiometer 46 ~ufficiently that the light increases from very faint to very bright over a very short period, such as 2 minutes. While this is not the preferred time interval from t3 to t4, the light increase will be smooth and gradual over this short time period to awaken the sleeper at his selected rate and is thus pre~erred to prior art devices. Preferably, the time period fro~
t3 to t4 is at least one-half hour and, ln some environments, is preferred to be approximately one hour, as selectable by the user. One significant advantage o~
this invention is that the user may set the time period from t3 to t4 to be equal to the sunrise time interval, the interval between when the sky begins to lighten in the morning and when the sun actually appears on the horizon, for his latitude and particular location. As is well known, the time that the sky begins to lighten until the sun rises is greater for greater di~tances from the equator. A chart or electronic table (not shown) may be provided to permit the user to set the time period from t3 to t4 to be similar to the sunrise time. Alternatively, an electronic circuit may be provided (not shown) which, by inputting the latitude, will automatically set the potentiometer 46 to the correct value corresponding to lighting of the sky related to the sunrise time for that latitude. A ROM or other electronic chip having a looX-up table tored therein and appropriate outputs to control the potentiometer 46 is a suitable circuit. The circuit may thus simulate the sunris for any given location and time zone on the earth. The simulation will be smooth and natural to set the internal body clock of the user in synchronism with his environment.
The time setting of the alarm clock is selectable by the user, based on whether the time represents the wake up time or the start of the wake-up 24 1 3 1 ~069 cycle. In the embodiment shown, the user sets the time t2 at which the alarm pulse is provided to start the wake-up cycle. Because the wake-up time is generally 30 or more minutes after the alarm pulse is provided, the user will set the alarm for approximately 30 minutes before he wiæhes to be awake.
In an alternative e~bodiment (not shown), the user sets the clock to hi~ desired wake-up time. The time interval from t3 to t4 has been previously selected, either by the user or by the manufacturer based on the setting of potentiometer 46. An internal circuit senses the value of potentiometer 46 and calculates the time from t3 to expected wake-up time based on the time interval from t3 to t4. The circuit timer sets the alarm clock to provide the alarm signal the number of minutes prior to the alarm being set for wake-up time as appropriate to awaken the user at the desired wake-up time. The user need not be concerned with the length of the time interYal from t3 to t4; the user need merely select a desired wake-up time and the circuit will begin to operate several minutes prior to this time to ensure that the sleeper will awaken at approximately the desired time. While a circuit to effect this second embodiment is not shown, a resi~tor bridge circuit, a ROM in combination with a simple logic array or microprocessor could easily be constructed by one of ordinary skill in the art to perform this function, given the description as provided herein.
Figures 4-9 illustrate an alternative embodiment for implementing the invention with a microcontroller and digital controls. A microcontroller chip made by Motorola, the MC68HC705C4, is suitable for implementing the invention in the digital format, as shown in Figure 5. The microcontroller of Figure 5 includes a built-in 8 bit 4K byte ROM, an B bit 176 byte static RAM and an 8 bit 240 byte bootstrap ROM. The operation of the circuit is largely software designed in a manner more fully described hereinafter to accomplish the functions of the invention digitally that are performed by the analog circuit. The circuit of Figures 4~9 may be use.d in place of the circuit of Figures 2 and 2A to drive the lamp 26.
The microcontroller of Figure ~ inclu~es 24 bi-directional I/0 lines and 7 input only lines. An on-chip oscillator is coupled to an RC or crystal/ceramic resonator 100 for onboard timing reference. The on-chip oscillator is periodically corrected based on the line frequency to ensure that the timing on the chip has the proper relationship to the line frequency. The chip also includes a memory mapped I/O, selectable memory configurations, bootstrap capability, power saving stop, wait and data retention modes, fully static operation, clock monitor, computer operating properly (COP) watchdog timer and software-programmable external interrupt sensitivity.
Any microprocessor capable of properly controlling the circuit of Figure 4 and providing the trigger signal 102 is suitable ~or use as the microprocessor in the invention.
Referring to FigurP 9, outputs PA2-PA7, PBO-PB7, PCO-PC7 drive the segments of the LCD display. A
suitable LCD for use in the application is the LTD 211 Rll produced by Amperex Corporation. The LCD provides read outs of real time, alarm time, status of the alarm, auto sleep and other circuit operations.
Pin PA0 supplies the trigger pulse 102 to pulse the optocoupler 104. A suitable optocoupler is the ~or 3010 available on the commercial market. A
pulse on the trigger line 102 causes current to flow through the LED 106 of the optocoupler circuit 104 to 35 turn on the triac 108. The triac 108 may be any triac having the appropriate power and response requir~ments.
A triac 108 which has been found suitable is the Teccor 26 131406q Q~008L4. The ~rigger ~ignal lo~ h~ ~r$ac 108 to ~egln to conduGt at a preoise tim~ in a cycle o~ tne power line drive voltag~, 109 ~1 ~co N. 13y vE!lrying ~he timing o~ the tri~ge~ elgnal 102 relativ~ to the line
The biological clock of a person operates, when possible, in synchronism with the sunrise and sunset at his position on the earth. When the biological clock is not in synchronism with their working day and the local sunrise and sun~et, mental ability and body performance are significantly lowered.
Recent studies of people suffering jet lag and of people working swing shift have demonstrated that mental and physical performance is impaired because their internal biological clock is not synchronized with their work day.
Unfortunately, many people in today's world are not able to take advantage of the natural light change at the start and end of each day. Many people must awaken and fall asleep on a schedule different from the rising and the setting of the ~un. For example, many people must be awakened before the sun rises in order to prepare for work and arrive at work on time.
Other people, such as those working a swing shift or living in a northern latitude in the summer, desire to sleep well past the sunrise time and be awakened later to prepare for and start their work day. Similarly, many people desire to remain awake after the sun has set and go to sleep on their own schedule, for example, after wat~hing a particular television program or the like. The schedule at which each person awakens and goes to sleep each day may be significantly differsnt from the sunxise and sunset times of each day.
1 31 ~06q It is therefore an object of this invention to provide a novel apparatus for varying the brightness of a light that causes a gradual and smooth change in theperceived light intensity.
According to the present invention there is provided an apparatus for varying the brightness of a light wh;ch is adapted to be powered by an AC power supply having æro-crossings, in a nonlinear power level as a function of time, comprising:
a circuit for providing power to said light from the AC power supply;
a zero-crossing sensor means for sensing each zero-crossing of said AC power supply and outputting a zero-crossing signal at each of said æro-crossings;
a precision timer coupled to the output of said zero-crossing sensor and receiving said zero-crossing signals, said precision timer outputting an oscillating frequency signal h~ving a plurality of zero-crossing points in between each zero-crossing of said ~C power supply and at least one of said oscillator zero-crossings occurring simultaneously with said AC power supply zero-crossings;
an electric circuit that generates a trigger pulse at a selected time after said AC
signal zero-crossing, said selected time being variable from a first time after said zero-crossing to a second time after said zero-crossing, said second time occurring more closely after said AC zero-crossing than said first time occurs after said AC zero-crossing, said selected time gradually varying from said first time to said second time after an input si~gnal goes high to cause the AC power supply to increase in a nonlinear power level as a function of time; and a switching circuit coupled to said electric circuit for causing a switch to turn on and provide power to said light ~rom said trigger pulse output going high until said AC power supply passes through a subsequent zero-crossing to thus control the intensity of said light based on said selected time of said trigger output line going high.
5a 1 3 1 4069 Preferably, an electrical pulse, such as from an alarm clock, begins the operation of the circuit at a preselected time. The intensity control circuit gradually and smoothly increases the RMS voltage applied to the lamp ~rom a low voltage level towards the line voltage level.
The intensity control circuit includ~s a capacitor in an RC circuit which is charging towards a final voltage. The voltage ~upply applied to the RC
circuit is a eonstant value with isolation to minimize th~ noise to ensure that the ~oltage level of the charging capacitor increases ~moothly. The output voltage of the charging capacitor is coupled to an operational amplifier. The output of the operational amplifier, having the charging capacitor as its input, is coupled to an operational amplifi~r having a negative gain. The output o~ the negative gain operational ,~5 1 31 406q amplifier is coupled to an "optocoupler" having an LED
adjacent a photoresistor. The negative gain amplifier is biased in the ~'on" itate, drawing current through the LED at all times. By having the LED in the "on"
position, the change in intensity in the lamp is very gradual, from a very low-intensity level to the high intensity level.
The photoresistor is part of a parallel resistive network, the network being in series with a triac. The value of the resistance network is selected to ensure that the RMS voltage remains below the level at which the lamp emits light until after the capacitor is past 6 percent of the time of the RC time constant.
The firing angle of the triac v~ries gradually and ~moothly to vary the RMS voltage applied to the light source from a 2ero-voltage level to the ~aximum available voltage levPl, such as line voltage.
Embodiments of the present inventio~ will now be described more fully with reference to the accompanying drawings in which:
Figure 1 is a block diagram of the electrical components of the invention.
Figures 2A and 2 are a circuit diagram of the components of Fi~ure 1.
Figure 3 is a wind~w diagram plotting numerou~
parameters Df the circuit of Figures 2 and 2A on the same graph.
Figure 4 is a ~chematic of an ~lterna~iv~
embodiment fQr drivin~ the variable voltage on the load.
Figure 5 is a ~chematic of a microprocessor controller for the alarm.
Figures 6-8 are schematics of ircuits coupled to the microprocessor of Figure 5.
Figure 9 is a schematic of the LCD display coupled to the microprocessor.
Ji ; ~.~,i .
7 1 31 406q The sensitivity of the eyes to light and variations in light intensity depends upon the state of the eyes, the background light, the wavelength, and ~ther factors. When the eyes have become adjusted to the dark, after a~out 30 minutes, the eye is at least 10,000 times more sensitive to light than during the day, when the eyes are not dark-adapted. When ths eye is dark-adapted, not only does the dilation of the eye change, the chemistry of the eye changes to make it much more sensitive to light and to changes in light intensity. A chemical called "rhodopsinl' is present in significant quantities in dark-adapted eyes but is absent in light-adapted eyesv The dark-adapted eyes can sanse even minute changes in light intensity, even below the level of consciousness of the person, when the background light levels are very low.
When the eye lids are closed and the person is asleep, a very faint light can be sensed by the dark adapted eyes. Signals are trans~erred to the brain and nerve cluster at the base of the brain, the suprachiasmatic nuclei, to began to slowly and gently change the body chemistry to prepare the body to wake up. As the light level increases, very small changes in intensity are sensed by the eye, because it is still dark-adapted, and the rate of change in the body's chemistry and internal wake-up clock can adjust to the gradually increasing intensity of the light.
Because of the sensitivity of dark-adapted eyes to variations in light intensity, a very smooth change in light level is preferred. If the increase in light intensity has step functions, jagged edges, or other irregularities, even very small irregularities, the eyes, being very sensitive, will recognize that the increase is not gradual nor constant and the waking process will be less pl~asant then it could otherwise be. The eye is most sensitive to changes in light 8 1 31 406q intensity at the ~ery start o~ the waking process, when the eye is completely dark-adapted and the background light levels are low. Therefore, it is most important that the increa~e in light intensity be very smooth~ and preferably slow, at the very beginning of the wake-up cycle. The circuit having the amplifier and LED biased into the "on" condition prior to receiving the wake up signal ensures that the increase will be very smooth and gradual, even ~rom the very beginning.
The circuit for directly controlling the light intensity of a lamp smoothly, gradually and automatically, similar to the rising or setting of the sun, is illustrated in block diagram form in Figure 1.
The circuit includes an input into a ~uf~er circuit 12 from an alarm clock 10. The alarm clock provides a wake-up signal at a preselected time, as determined by the user. Any standard alarm clock circuit may be used to provide the signal, as is well known in the industry.
The bu~Per circuit 12, a~ter appropriate ~0 amplification and filtering, provides a signal to charging circuit 14 to begin varying the voltage applied to a lamp 26. The charging circuit is coupled through an amplifier 16 to the LED of an optocoupler 18.
Varying the intensity of the LED in optocoupler 18 causes the power provided to lamp 26 to be varied. The power is varied by changing the ~iring of the angle of a triac in power supply circuit 20 coupled to line voltage source 24. The particular voltages and power required for the respective circuits are pxovided by DC power supply 22, which receives input power from line voltage power supply 24. The power provided to the lamp 26 may be directly controlled, either decreased or increased or preset to a selected level, by the manual circuit 28 : coupled to charging circuit 14.
A detailed circuit diagram of the clock circuit of Figure 1 is illustrated in Figures 2A and 2.
An alarm clock circuit 10 is coupled to an alarm node !3 1 3 1 4 0 1~ 9 input 30 of the buffer circuit 12. The buffer circuit 12 inclu~es, in one embodiment, an amplifier 32 coupled through a capacitor 34 to alarm circuit input 30~ The gain of the amplifier 32 is determined by the value of resistors R24 and R25, as is well known in the art. The output of the amplifier ~2 is coupled, through a capacitor 36, to the input 38 of the charging circuit ~4~ In an alternative embodiment, Option 5, th~ huffer circuit 12 includes a light-emitting diode 35 adjacent a light-sensitive transistor 37 coupled to the input 38 for providing the signal ~rom the alarm input 30 to the charging circuit 14.
The input 38 to the charging circuit 14 is coupled to the set input of RS flip-flop 40. The filter capacitor, C10, at the triggering input 38 filters transients tv prevent false triggering which may be caused by power line surges, glitches, or other transients. Resistors R22 and R23 bias the set input to flip-flop 40 at half of the power supply voltage, Va, for noise rejection. The output, node f~gj, of the flip-flop 40 is pulled up to a given voltage level, usually the level of the positive power supply, Va, on the negative-going pul~e at the input 38 of node f(f~.
The output, Q, of RS flip-flop 40 is coupled through 25 resistor network R17 and R16 to zener diode 42. The : voltage of the output of the flip~lop 40 i5 reduced in node f~h) by the resistive network R17 and R16 to a value within the range of the most stable operational range of the amplifier 48 Por the time period of particular concern. In a preferred embodiment, this value is approximately 4 volts, though any other suitable value may be used. A zener diode 42 is selected having a very high reverse impedance to minimize the leakage through it from capacitor 44.
The time constant of the RC circuit formed by potentiometer 46 and capacitor 44 is given by the equation:
lo 1 3 1 406q T.C. = RC (1) where T.C. is the time constant of the RC circuit.
Potentiometer 46, Yr2, is salected to be relatively large to provide a long-time constant and a slow charging rate o~ the timing capacitor 44. The resistance of potentiometer 46 is manually adjustable by the user at control 43 to set the time constant at any de~ired value, generally from as low as two minutes to greater than ten hours.
The voltage of the timing capacitor 44 is coupled to the input of amplifier 48. The amplifier 48 is selected to have an extremely high input impedance, for example, over a billion ohms or greater, to minimiz discharge through it of the timing capacitor 44. An FET
input opamp is suitable for amplifier 48. The ampli~ier 48 operates as an isolating buffer, similar to an emitter follower with a gain of one. The output at node ftj) of amplifier 48 sxactly follows the input from the timing capacitor and is equal to it.
The output f(j) from the amplifier 48 provides the output from the charging circuit 14 and the input into the amplifier circuit 16. The amplifier circuit 16 includes, in the preferred embodiment, an inverting ampli~ier 50 having a negative gain. The output of amplifier 50 to node f(l) is biased to a negative startinq point by a constant negative-bia~ed voltage at node f(k). The input from node f(j3 to amplifier 50 is to the inverting input and therefore inverts the signal from the output of operational amplifier 48. The gain of operational amplifier 50 is determined by the ~ equation:
: R10 Gain = - (2) ~11 The gain is selected to be a value less than one by makinq Rll greater than R10.
~1 1 3 1 ~069 The gain o~ amplifier 50 i5 made negative to ensure that the operation i~ stable. By making the gain negative, many advantages are achie~ed in providing a more stable output. For example, the amplifier operates in the middle o~ it~ rated rang~ at all times and does not operate at either end of its rated range, where the output is less stable. Further, variations in the input, including any noise, are reducad rather than amplified~ This makes the output more smooth and stable. The circuit providing power to the LED need not include a negative gain amplifier so long as the circuit provides a sufficiently smooth and stable output. It has been found that use of a capacitor followed by a negative gain operational amplifier is one way to achieve a su~ficiently smooth, ~table output.
A constant~ negative-biased voltage is provided at node f(k), as determined by the equation:
f(k) = R13 + R12 x Vc (3) The constant, negative-biased voltage f(k) provides a negative voltage base level at the output node f(l~ of operational amplifier 50, while the input from node ~(j) determines the additional negativ~ swing at ~he output, giving a total output f(l), which is equal to the amplified combination of the voltage on the timing capacitor f~i) and the negative-bias~d voltage f(k).
The voltage on the node f(l) is given by the equation:
R13 x Vc x (R10 ~ Rll) R10 ~13 + R12 f(l) = f(i) x ~ Rll (4) (Part A) (Part B) 1~ 1 31 4069 When the capacitor is not charging, the voltage of node f(i) is zero volts and Part A of the equation goes to æero, resulting in the voltage at node f(l) on the output of operational amplifier 50 being determined solely by the constant negative-biased voltag~, as given by the Part^B of the equation. In the preferred embodiment, the constant negative-biased voltage at node f(l) is 1.5 volts, based on a selection of an amplifier havin~ very stable operation in that range and to avoid transient responses.
The output of amplifier 50 is coupled to the LED 52 of the optocoupler circuit 18. The LED 52 is held in the "on" state at all times by the output from amplifier 50. The constant, negative-biased voltage of the amplifier 50 is selected to provide an output to the LED 52 which holds it in the "on" state in a range of stable operation. Generally, this range o~ operation will be just slightly above the voltage at which the LED
begins to conduct and is fully "on.'^ It is selected to be above the voltage at which the LED switches "on" to ensure that discontinuities, glitches or transients often occurring with an LED switching from "off" to "on~
are avoided.
The change in current through the LED 52 is directly controlled by the charging capacitor 44. Ths voltage on the charging capacitor 44 at node f(i) is given by the equation:
f(i) = tf~h) x (1 e(t/T C )~]
Where t is the elapsed time in minutes since the alarm signal set RS flip~flop 40 to start the charging of the capacitor and T.C. is the time constant of the RC
circuit in minutes.
The optocoupler cell photoresistor 54 is part of a parallel with a resistor network 56 of lamp pow~r circuit 20, as shown in Figure 2. R~sistor R2 and 13 13~4069 photoresistor 54 form parallel resistance network 56.
The parallel resistive network 5~ is coupled in series with resistors R1 and R3 to the gate o~ the triac 58.
The total resistance of the parallel resistive network 56, RNt, is given by the equation:
1 ~ x R2 . = . (6) 1 1 ~ + R2 _ ~ _ ~2 The optocell 54 is selected to have a very high resistance, ~, relative to resistor R2 when the LED is biased in the just slightly "on" conditio~ by the output of amplifier 50. With the LED just slightly "on," the resistance, value RNt~ of the parallel resistive network 56 will be approximately egual to the resistance of R2, as can be seen from Equation 6, because ~ is so much higher than R2. The series resistance of Rl, R2 and R3 is selected to ensure the firing angle of the triac 58 is so high that the lamp does not emit light.
;The value of ~, with the LED in the slightly "on" state, is in the range of 100 to 10,000 times greater than R2. The exact ratio selected depends on the rate at which the resistance is desired to be lowered in response to the gradually increasing brightness of the LED 52. In a pre~erred embodiment, R2 :is 56 kohms and ~ varies from above 1 Mohms to :~30 approximately 300 ohm Because ~ is so much greater ~:than R2 when the lamp begins to emit light, linear changes in ~ effect very, very small, nonlinear changes in RNt, and thus increase the brightness of lamp 26 only a very small amount. For example, when ~ is much greater than R2, if ~ decreases 1000 percent, the network resiatance, RNtt will decrease less than percent. As ~, starting at a differ~nt value is reduced, ~or example, ano~her 1000 percent, this may decrease RNt by about 10 percent. As Rp becomes almost equal to R2, further changes in ~ produce a greater percentage change in RNt. For example, a 10% change in may produce a 5% change in RNt. As Rp continues to go lower~ so as to be much lower than ~2, the value of Rp becomes controlling and the network resistance RNt will be approximately equal to ~ and will follow it almost exactly. The exact rate of change can be seen by plotting ~ versus RNt based on Equation 6.
The use of a single resistor in a parallel resistive network to control the firing angle of the triac causes the intensity variation of the light to be very, very gradual and slow at the low light levels, but the rate of intensity variations to be greater at higher light levels. A very gradual increase at a low light intensity level is preferred for this invention because the human eye is much more sensitive to variations at low light intensities with low background light than to variations of high light intensities with a high background light level, as is well known in the art.
The dark-adapted eye of the sleeping person is particularly sensitive to changes of intensity at low light levels. The use of a parallel resistive network and selection of R2 and ~ provide that changes in light intensity occur ~ery slowly at low light levels and more rapidly at high light levels for awakening a sleeping person. To the eye of the sleeping person however, the light intensity increase is gradual and steady because the eye becomes less sensitive to changes in intensity as the light increases, as discussed in Patent No.
3,684,919 to Cramer.
~ Additional parallel reslstors or parallel photoresistors ; adjacent the LED may be us d if desired~
As the resistance of the parallel resistive network, RNt, decreases, the total series resistance decreases, thus lowering the firing angle of the triac 58. As the firing angle of the triac 58 is lowered, the RMS voltage provided to lamp 26 increases accordingly.
! i Ji The use of an optocoupler circuit isolates the lamp power supply circuit 20 from the remainder of the circuit~, allowing the power ~upply 22 to be transformerless. The RMS voltage provided by the lamp powar supply circuit 20, including the triac 58, smoothly and gradually increases. ~he net resistance of the series resistors Rl, RNt and R3 determine at what angle the triac 58 begins to ~ire. The combination of capacitors C1 and C2, in parallel with rasistor R3, acts as a ~ilter to prevent false firing of the triac 58, which may be caused by transients, harmonic response or the like. The combination oE inductor Ll and capacitor C3 filter out power line transients and the like caused by the firing of the triac or from the power line. A
fuse 60 is provided to ensure that the circuit is not damaged due to overloading.
The power supply 22 provides the DC voltages for circuit operation. A positive voltage, Va, is provided to the respective circuits, as indicated in Figure 2A. A neqative voltage, Vc, which is the opposite of Va, is provided to the circuitry, as shown in Figure 2A. Zener diodes D2 and D3 and capacitors C4 and C5 are selected to ensure that Va iæ always equal to negative Vc. A common voltage source (com) is provided in the node between capacitor C4 and C5 in the power supply 22, a~ shown in Figure 2. The common (com) supplies the reference ~or all other supply voltages and acts as system ground. The zener diode D4 is a backup diode and prevents possible damage to the circuits if one of the zener diodes, D2 or D3, fails. Diodes D5 and D6 rectify the input line voltage across f(a). Diode D5 is provided as a backup diode in the event diode DS
fails.
The lamp 26 is coupled to the lamp power supply circuit 20 using any one of several known wiring patterns. In Option 1, the lamp 26 is wired as a main light in a room~ the light being in the ceiling and the 16 1 31 ~ 069 switch being located on the wall. The master light in the room, such as the one mounted in the ceiling, is generally positioned sufficient near the sleeper to awaken him. For Option 1, the input power is provided from one wire going to the lamp, the lamp being in series with the various circuits of this invention. The power provided to the circuit will be lowered by the voltage drop across the lamp 26 whan the lamp is coupled using the wiring pattern of Option 1. For Option 1, regulation of the power supply is provided by the series regulator circuit combination of Q1, R5, R6 and D7; all of which dissipate virtually all of the power ~upply's heat. R5 is selected to be large enough to limit the current of Ql to a safe value. D7 limits the peak base voltage of Q1 to a saPe value. C6 filters out transients from the power supply to prevent false triggering of the flip-flop 40 in the charging circuit 14. The alternative circuit having transistor Q1 is required to regulate over a relatively large range, from about 105 volts RMS to approximately 20 volts RMS, because, as the lamp increases in brightness, the voltage f(a) provided to the power circuit is correspondingly decreasing.
The lamp 26 may alternatively b~ connected as shown in Option 2 of Figure 2. In Option 2, a standard house plug is provided for the circuits of this invention to be plugged into any desired wall outlet. A
industry standard-sized wall outlet 26 is provided into which a lamp (not shown) may be plugged. The power provided to outlet 26 for the lamp follows the power curves described herein to permit the power to the lamp to be varied as described.
A power supply for an ~larm clsck may be provided by Vb from the power supply, a~ illustrated by an alternative embodiment of Option 3, if desired. R7 and R8 perform a divider for clock supply voltage, which is filtered by C7.
17 131~,069 The manual switch control 28 provides manual control of the light intensity to a selected value.
Switches are provided to permit the user to manually select a light inten6ity value or to move the light intensity up or down. One switch, SW1, selectively couples the charging capacitor to ground through a bleed resistor R20 to discharge the circuit and turn the lamp "off." The discharging of capacitor 44 through bleed resistor R20 can be stopped at any time by the user to hold the intensity of lamp 26 at any desired level. The leakage of capacitor 44 is sufficiently low and the resistance presented by zener diode 42 and amplifier ~8 are suffici~ntly high that the intensity of the lamp 26 will remain constant ~or several hours, or even days.
Another switch, SW2, may be depressed to gradually manually increase the light intensity to any desired level by manually charginy the timing capacitor by directly coupling the timing capacitor to the voltage supply Va through resistor R18, having a significantly lower value than potentiometer 46.
The operation of the circuit can be understood by viewing the relative voltages at each of the nodes and the relationship between them, as shown in Figure 3.
At a time tl, a start pulse is provided by an alarm clock or other external circuit to begin the operation ~, of the circuit. A negative-going pulse to the input of the RS flip-flop 40 causes the RS flip-flop to come "on"
at a time t2 and remain on until the circuit is reset.
As shown in Figure 3, the charging capacitor 44 begins to charge from a low voltage level at time t2, approaching a maximum voltage as determined by the resistive network R17 and R16. The time taken for the capacitor voltage to reach the final voltage is : determined by the time constant, as previously described. After 6~2/3 percent of the time constant has passed, the voltage at the charging capacitor in node f(i3 reaches a level at which the lamp 26 begins to emit 18 1 31 ~ra69 a faint glow, visible to the dark-adapted eye, as indicated by time t3 in Figure 3. The voltage on the charging capacitor continues to rise in a gradual, smooth and linear fashion from t3 to t4. The time t4 is 20~ of the time constant of the RC circuit. The voltage level on the capacitor, to which node f(i~ is charged, will be significantly slower in charging after 20 percent of the time constant has elapsed, as the voltage increase on the capacitor approaches the final voltage f(h). However, for the time period from t3 to t4, the voltage rise in node f(i) is extremely smooth, gradual and generally linear. The tima period from t3 to t4 represents the time period in which the lamp first begins to glow in a manner perceptible to the most sensitive eye at time t3 until the lamp is sufficiently bright at time t4 that further increases in lamp voltage do not result in intensity changes detectable by the human eye.
The output of operational amplifier 50 is illustrated in Figure 3 as the voltage at node f(l)~
The voltage is biased to a negative value, such as 1.5 volts, by the resistive network R13 and R12, as amplified by the operational amplifier. The operational amplifier 50 is held in the "on" position and in a stable operating range at all times to minimize the occurrence of transients associated with the turning "on" of the amplifier, LED and the like. Further~ the LED is turned "on" at all times, previous to the capacitor 44 being charged, to ensure that transients associated with the switching "on" of the LED do not affect the intensity of the lamp 26.
The beginning of the charging of the capacitor 44 represents a zone of safety below which the lamp voltage f(n) remains so low that the lamp is in the "off" condition. The gain of amplifier 50, value of resistors R3, R2 and Rl, and the operating characteristics of photoresistor 54 and triac 58 are 19 131~V69 salected to ensure that the lamp does not emit light during the initial charging o~ the timing capacitor 44.
This zone is generally selected to be at least 5 percent o~ the time constant of the voltage rise at the node f(i) and, in a preferred embodiment, is 6^2~3 percent o~
the time constant of the rise in voltage at f(i). This safety zone prevents the lamp ~rom lighting during the initial charging state of the capacitor 44. This ensures that transients associated with the beginning of the charging of the capacitor do not affect the changes in light intensity o~ the lamp 26. When the voltage at node f(i) reaches the level of approximately 6~2/3 percent o~ the time constant, the output of the amplifier 48 drives the output of th2 amplifier 50 in node f(l), sufficiently negative to lower the combined resistance of the optocoupler resistor 54 and R2 to a value at which the firing angle of the triac provides suf~icient power to the lamp that the lamp emits a faint glow, a very low-intensity light. The glow is sufficiently faint that in full day light or in a room of high background light, the human eye does not datect the lamp gl~wing. However, after th~ person has been asleep for many hours, the dark-adapted eye is lO,OOO
times more sensitive to light than during the normal waking conditions. The eye of the sleeping person, therefore, detects a faint glow co~ing from lamp 26 and transmits this information to the brain of the sleeper, even though the voltage on the lamp 26 is extremely low, for example, 6 to 8 volts RMS.
The voltage on the lamp f(n~ rises from zero volts RMS towards line voltage, ~or example, 120 volts RMS at time t4. The voltage across the lamp will grad~ally and smoothly increase according to the equations as provided herein towards full li~e voltage for the lamp, which is approximately 120 volts in Option 2 and approximately 105 vo~ts in Option ~ter time t4, t~e li~ht i~te~si~y ~ay contin~e to ,inçr~~
1 31 4 06 q measured by instruments, if desired, but the light is sufficiently bright that further increases in brightness of the lamp are not detectable by the human eye.
Generally, the time from t3 to t4 will be in the range of 30 minutes to 45 minutes. The user may ~1ect the time from t3 to t4 to be significantly greater than an hour or as low as 2 minuteg, depending on a desired time to wake up by varying the value of p~tenti~meter 46, using a manual adjustment knob 43.
one o~ the ~ignificant advantages of this invention is that each of the components operates within stable operational windows when the lamp 26 is emitting light. The capacitor 44 is selected to have very stable and linear operation as it charges from zero to a voltage just above the start of the charging curve to the maximum voltage provided at node f(h). A capacitor having sta~le operation in this voltage range will often have a top operating range signifi~antly higher than this voltage.
Amplifiers 48 nd 50 are selected which have very stable output characteristics over their range of operation. Usually the amplifiers will be operated in the middle of their rated range to ensure that the operation is stable. For example, the output of amplifier 50 varies from a low of 1.5 volts to a high of 1.75 volts corresponding to the lamp 26 being off to the lamp 26 being sufficiently bright that further increa~es in intensity are not d~tectable. While this is a very small voltage swing, amplifier 50 is very stable over this range and is thus suitable for varying the current drawn through LED 52. Similarly, LED 52 is held "on" at all times to ensure that its operation window is within the range of stable operation of the LED. Each of the components and the respective voltages at sach node are selected to ensure that each device is operating in a stable window of operation during the time period from t3 to t4 when the intensity in lamp 26 is varying to provide a very smooth and gradual intensity curve to gently and smoothly awaken the sleeper. It is not required that the amplifier 50 and LED 52 be on at all times to ensure stable operation of the circuit. One method to ensure that tha circuit elements are in stable operation from t3 to t~ is to have them "ON" prior to t3. One way to ensure that the elements are l'0N" prior to t3 is to bias them "ON" at all times; but other techniques may also be used.
Figure 3 illustrates the operational windows by including several parameters, plotted along a common time line but having significantly different values.
The graph of Figure 3 has the common time line of the time constant of the RC circuit formed by potentiometer 46 and capacitor 44. The time line increments are based upon the percentage of the time constant of the RC
circuit, rather than on real time in seconds. The charge on the timing capacitor f(i) is represented by the curve f(i), as indicated, showing a safety margin of 6^2/3 percent of the time constant of the RC circuit, prior to the remaining elements in the circuit permitting the voltage to be sufficient to cause the lamp to begin to glow in a manner perceptible to the dark accustomed eye. The lamp voltage f(n) is shown as a function of the time constant and will reach approximately 90 percent of the line voltage after 20 percent of the time constant of the charging capacitor has passed. The firing angle resistance of the triac 58 varies, as shown in Equation 6, in a smooth pattern, as the voltage on the timing capacitor increases. The output of the amplifier 50, f(l), the driving voltage of the LED 52, is a negative voltage and becomes more negative as the timing capacitor increases. The LED 52 is always operated in the stable range of operation to ensure that all changes in the intensity of the light are gradual and smooth. In the upper range of operation, after 20 percent of the time constant has 22 13140~'~9 pas ed, at relatively high voltages, the lamp voltage may include some transients no occurring during the low voltage operation of the lamp but these do not interfere with the basic operation of ths invention. Such transients are permissible because the lamp is sufficiently bright that the human eye cannot detect changes in the brightness of a light which is already extremely bright.
The user can be gently and comfortably awakened using the lamp 26 of this invention as his alarm clock. The brain of the sleeper receives the signals from the eye that the room is beginning to brighten. As the light continues to very slowly increase in intensity, the rate of increase is also sensed by the brain. The brain sends out the appropriate control signals to start changes in the body chemistry o~ the sleeper. Even though the person is sleeping and may be in a very deep sleep at the time the light first emits a faint glow, the gradual increase of light over a one-half hour to one hour period brings the body functions slowly up to the waking state. By ensuring that the initial light intensity is very low and that all increases are very gradual and very smooth, especially at the beginning of the wake-up cycle, the body of the user is very gently and comfortably awakened. The jolts and sudden changes oP state in the body of the sleeper caused by the prior àrt devices are thus avoided. Upon awakening, u~ually when the light is quite bright, the sleeper's body chemistry has adjusted to be prepared for the waking state. The user feels refreshed and ready to become active, rather than being irritable, grumpy and nonfunctional for a period of time. Some results of experiments indicate that perPormance throughout the day is significantly improved when the person has been awakened using the device and method of this invention.
23 l 31 4069 The rate o~ light increase is fully selectable by the user. The user may lower the resistance of potentiometer 46 ~ufficiently that the light increases from very faint to very bright over a very short period, such as 2 minutes. While this is not the preferred time interval from t3 to t4, the light increase will be smooth and gradual over this short time period to awaken the sleeper at his selected rate and is thus pre~erred to prior art devices. Preferably, the time period fro~
t3 to t4 is at least one-half hour and, ln some environments, is preferred to be approximately one hour, as selectable by the user. One significant advantage o~
this invention is that the user may set the time period from t3 to t4 to be equal to the sunrise time interval, the interval between when the sky begins to lighten in the morning and when the sun actually appears on the horizon, for his latitude and particular location. As is well known, the time that the sky begins to lighten until the sun rises is greater for greater di~tances from the equator. A chart or electronic table (not shown) may be provided to permit the user to set the time period from t3 to t4 to be similar to the sunrise time. Alternatively, an electronic circuit may be provided (not shown) which, by inputting the latitude, will automatically set the potentiometer 46 to the correct value corresponding to lighting of the sky related to the sunrise time for that latitude. A ROM or other electronic chip having a looX-up table tored therein and appropriate outputs to control the potentiometer 46 is a suitable circuit. The circuit may thus simulate the sunris for any given location and time zone on the earth. The simulation will be smooth and natural to set the internal body clock of the user in synchronism with his environment.
The time setting of the alarm clock is selectable by the user, based on whether the time represents the wake up time or the start of the wake-up 24 1 3 1 ~069 cycle. In the embodiment shown, the user sets the time t2 at which the alarm pulse is provided to start the wake-up cycle. Because the wake-up time is generally 30 or more minutes after the alarm pulse is provided, the user will set the alarm for approximately 30 minutes before he wiæhes to be awake.
In an alternative e~bodiment (not shown), the user sets the clock to hi~ desired wake-up time. The time interval from t3 to t4 has been previously selected, either by the user or by the manufacturer based on the setting of potentiometer 46. An internal circuit senses the value of potentiometer 46 and calculates the time from t3 to expected wake-up time based on the time interval from t3 to t4. The circuit timer sets the alarm clock to provide the alarm signal the number of minutes prior to the alarm being set for wake-up time as appropriate to awaken the user at the desired wake-up time. The user need not be concerned with the length of the time interYal from t3 to t4; the user need merely select a desired wake-up time and the circuit will begin to operate several minutes prior to this time to ensure that the sleeper will awaken at approximately the desired time. While a circuit to effect this second embodiment is not shown, a resi~tor bridge circuit, a ROM in combination with a simple logic array or microprocessor could easily be constructed by one of ordinary skill in the art to perform this function, given the description as provided herein.
Figures 4-9 illustrate an alternative embodiment for implementing the invention with a microcontroller and digital controls. A microcontroller chip made by Motorola, the MC68HC705C4, is suitable for implementing the invention in the digital format, as shown in Figure 5. The microcontroller of Figure 5 includes a built-in 8 bit 4K byte ROM, an B bit 176 byte static RAM and an 8 bit 240 byte bootstrap ROM. The operation of the circuit is largely software designed in a manner more fully described hereinafter to accomplish the functions of the invention digitally that are performed by the analog circuit. The circuit of Figures 4~9 may be use.d in place of the circuit of Figures 2 and 2A to drive the lamp 26.
The microcontroller of Figure ~ inclu~es 24 bi-directional I/0 lines and 7 input only lines. An on-chip oscillator is coupled to an RC or crystal/ceramic resonator 100 for onboard timing reference. The on-chip oscillator is periodically corrected based on the line frequency to ensure that the timing on the chip has the proper relationship to the line frequency. The chip also includes a memory mapped I/O, selectable memory configurations, bootstrap capability, power saving stop, wait and data retention modes, fully static operation, clock monitor, computer operating properly (COP) watchdog timer and software-programmable external interrupt sensitivity.
Any microprocessor capable of properly controlling the circuit of Figure 4 and providing the trigger signal 102 is suitable ~or use as the microprocessor in the invention.
Referring to FigurP 9, outputs PA2-PA7, PBO-PB7, PCO-PC7 drive the segments of the LCD display. A
suitable LCD for use in the application is the LTD 211 Rll produced by Amperex Corporation. The LCD provides read outs of real time, alarm time, status of the alarm, auto sleep and other circuit operations.
Pin PA0 supplies the trigger pulse 102 to pulse the optocoupler 104. A suitable optocoupler is the ~or 3010 available on the commercial market. A
pulse on the trigger line 102 causes current to flow through the LED 106 of the optocoupler circuit 104 to 35 turn on the triac 108. The triac 108 may be any triac having the appropriate power and response requir~ments.
A triac 108 which has been found suitable is the Teccor 26 131406q Q~008L4. The ~rigger ~ignal lo~ h~ ~r$ac 108 to ~egln to conduGt at a preoise tim~ in a cycle o~ tne power line drive voltag~, 109 ~1 ~co N. 13y vE!lrying ~he timing o~ the tri~ge~ elgnal 102 relativ~ to the line
5 vol~age cycle, th~ RMS volt~ge, an~a tnu~ ps~wer, provided ~c~ the loa~ Z6 i3 v~ried.
A~ lg known, onc~ tr~ggered, ~ triac rem~in~
on until the power ~3ignnl r~ h~ a ~o cr~inçl, which r.,a~e~ 'ch~ t~iac to turn ~ . When th~ loa~ in the 10 ~ c~nditio~, ~nP ~risgo~ 102 ~ p~o~J~dod very late in the power lino ~y~le, for exa~nple at 17~ or 180 ~agreQs.
If the trigg~ 102 1~ ac~l~ra~ed ~t 175 dogr~s in the cycle ~ 'ch~ R~8 powrar reachin~ th~ load is ver~l~ low . As the f lring angl~ is daceasQd rrom 17~ ~e~r~e3 tow~ds~ 5 15 deç~ree~, th~ pow~r applied to the load lncrea~e~.
A zero cro~5ing Bignal llO driv~ ran~ or 112 ~ ~he ~utput o~ ~h~ tran~tor 112, I~Q corre~t~ the mlcrocont~oller chip's timing p~lodlcally to ~n~ur4 that it i~ in ~tep with tha ave~ag4 11ne ~re~uency at 20 the zero c:~0~slnç~ ~oint.
q~h2 Z MRz ~ erens~ 4~11ator 1~0 iY, ~or~ed with tho c:ryf~tal 114, c~pacitC~r~ 116 antl 118 arld r~ ;tor 120 coupled So pin~; 3~ ~nd 39 ~8 shown in ~igUr~ 5 ~ Uao~ depre~ e witch~g 12~ proYide control 25 of the microproce~gor operation~ The u~ar d~pr~ible switcho~ i~clud~ a r8s4t, a mode ~ale~t, manual up and manual down, alarr~ enable, au~o ~im and ~ime ~adjus~ment ~apabilities .
Power iB pro~ided to the tnlaroprl~c~6so~ of 30 Figure 5 by t~e bridge r~tifier oir~ui~ 128 o~ Figllre 4. A diode rQcti~ying brldg~3 128 is ~od t2~rough an ~ola'cion dio~ 130 to ~ ~rolt~o r~ tor 13~.
~hRrgin~ fo~ ~he backuD ~att~ry 134 ia provide~ a~
~oltage ~JA ~r~m tne lnput circui~ Diode6 1~6 a~d 1 3a 33 ACt' ~ a ~urre~t ~t~er$ng circuil: to Gouple th~ batt~ry 134 to the 8ySt:21D if ~he line ~roltag~ go8g down. If th~
line ~rolt~ge y~s down, th~ chip conr.ection~ to YC c ~
1 31 406q to ~ro volt~ hu~ing down the ~ortions o~ th~ clrcll~t whlch u~e a hl~h opera~lng cur~en~, ~uch ns tha ~¢D
reoi~tor network, th~ opt~coupl~r to ths triac circult ~nd th~ likQ. Th~ backup ~at~ery ~olt~ge vl3AT 1 provided by the battory to the mioroaon~ollsr 140, ~aving the baE~ memory. ~he ~a~Rup ~lrcuit al~D
includ~s thel cira~it ~ Fi~uro 7 having a dio~ and a on~ miarof ar~ed capa~itor ~o protect the chip rrom pow~r ~ump~ tl~at could onu~ r~ti~ ope~atior~ 4~ th~a ch~p al~d 10 also to supply ~ r~et pulse RES ~o the Chip when t~e lihe power ~ola~3 down.
Re~errlng to Flgures 4 and 5, th~
mlcrocontroller 14~ ha~ ~een p~rc1~6mo~ 5~pp~y t~CI
powor curv~ to control the tiDIinç~ of th~ tr~ gger pul~e 15 142 to th~ trlac~ math~-tatlaal ~o~rnul~ ~or th~
contr~ r ~ f ol low~
ao V~ 200 ~ ~
load volt~a~e QS~UAl# 'cn i Z ~cu~ed ClVid~d by 20Q3, wh~re tn ls the tim~ ~lnc~ th~ nL eign~l. A~ th~ ti~
~since t~e al~rm (tn) inc~ea~es, up to 26 minutes maxi~u~, tne ~crl~g~ pul~ o th~ tri~cl d~Por~aa~e6- frorn ~pproxin~ately 175 degree3 firing angle ~o apprexima'cely 5 degr~s ~lrlng angle . Tt~e timing o~ the trigger pul E:o ie aloo ~crib~d in rela~ n to ~he pha~e an~le, tha'c is ~he ~iring angle ~ ~he ~rl~c 108 wit~ r~latlon~h~p t~ thOE lin~ volt~ge.
PhaoeAnç~ P~
175.5 ~ .2stn - o.~ tn2 + ~xlo ~4 tn3 ~4) wh~re the phase angle i~ thc ~ngle o~ the 1 i ne vol~age - lOY rrOD I.l to N ~ PLgu~o 4 o.t whi~h ~ tr~ggf2r i~
3ctiv~ted arld tn i3 the time elap~ nce ~he alarm 3S occurre~.
The manual cont~ol ~wi1~che3 122 to the mic:r~con'croller oLe Figur2 ~ ~re defin~d ~ foll~w~:
:~eaet 63top~ ~ha ~uto ~larm or auto dim op-ra~-ion at the llqht le~el ~It th~t moment ~d ~ w~ th~ nuqll contro~9 for ~incr~3~3el' ar~d ~de¢~ea6eH to be u~ed. Mo~ie ~3~3t~3 th~ "ml~de" t~ ith~r (a) alarm ~me abl di~iplayed 6~n th~ l) and a3 ~et by ~he u~r or ~b) real t ~ me ~
di~ ay~d on ~Ae L.CD and ~ounting. Alarm 15n~bie actl~a~3 tho alarm to ~ause th~2 E;iqn~l t9tn~ ~:D b~g~n ene coun~ rrom zero cnw3rd . AUtO Dlm act lv~e~ ~ne au~¢o dim c1p~ratiDn where the lE~el o~ ~e ligh~ at thQ ti~e ~-h~ auto d~m ~u~ton ~ depres~ied begin~ to decrea~e 10 S~llowin~ th~ ~cnt-a fD~ulae until the lighi; 1~
compl~t~ly out~ ~ auto ~ utt~n c;au6s~ the light ~o oporato in th~ oppo~ m~nn~r ~o thL alnr~ nn;7dc ~1D
th~t the light level i~ decr~a~ing base~ on th~ pr~
~o~mulA r~ r th~ln ino~e~l~in~. The Tiw~ ~dju~t E3witCh 15 pe~rmit6 a~iu~tmer~t o~ the ~im~ in the Alana mode~ or re31 t~m~ ~od~ as~ pr~iou~ly ~ us~ed. When th~ tim~3 ad~us~t i~ depre~sed, the ti~e is inarea~e~ in ~inu~es ~nd ln nour~ a~ contrt~llecl by tt~e u~ex ~ when ~ne in~l~at~d tim~ e~u~l~ the de~ired E:et tlme, t~e b ~tton ~ s 20 r~le~od. Proqr~nmin~ o~ man~lal button~ to aocompli~h thic~ aro we~l Xnown in the ~rt.
Flgure 4-g lllu~rat a particular dig~lt~l airaui~ mi~rooont~olle~ ~or r~ irJg th~ inv~:rtlo~
5h~ circuit include~ dig~tal oo~pon~t~ ~uch a~ ~h~
25 mlc~oc~ trolle~r 140 ~In~ ~nnlog co~pon~:nt~ ~uDh n~ tbe lin~ ~oltag~ ~ro~o I.l to N and triac 108. Any o~h~r digital ~;:ircuit cilp~ble o~ perrorming a ~;imi'l ilr ~ ti~n would ~e ~;uitabl~ for u~e in pl~c~ o~ t sht~wn.
The invention may also b~ U od to aid 30 pc3r~:o~, p~icula:~ly an in~ant~ in ~all~ a~l~4p. 5h~
charge on ~apacit~r 44 ~ay b~3 filowly blad o~ through po~n~iometer J,5 by ~oupl~n~ th.l3 othe~ r31de ~f pot~ntlom~t~r 46 to ground through E~ swi~oh. Th~3 u~r m~y ~et: ~he ligh~ to ~e f~lly or part~lly on e~7;d tht~n 3S ~at t~e a~itch to 310wly bleed d~wn capac$tsr 44 through po~ontio~et~r 46. The ir~n'c ~rill G~m~ bly lie i~
bed without havin~ to be afraid o;e the d~rk. Over a 30-29 l 3 1 406q minute to 2-hour period, as determined by the setting of potentiometer 46, the light intensity will slowly decrease using the same circuit and principles as described herein for increasing the light. The infant will fall asleep as the light lowly grows dimmer. The in~ant will be asleep prior to the lamp going out completely and will thus have a gentle and ea~y sleep.
The same light may be used to awaken the infant at a given time the next morning, based on a similar time interval, if desired. The infant is thus allowed to fall asleep without fear. The circuit may also be used by adults, if desired, to ease them into a sleepy state based on changes of light to simulate tha setting of the sun.
While a lamp 26 has been shown as the load, any other load to be smoothly driven may be used. For example, a motor, drill or inductive load or other load may be driven by the circuit of this invention. A
switch to permit the power provided to the load to be rapidly and manually variable as directly controlled by the user may also be provided if desired.
A~ lg known, onc~ tr~ggered, ~ triac rem~in~
on until the power ~3ignnl r~ h~ a ~o cr~inçl, which r.,a~e~ 'ch~ t~iac to turn ~ . When th~ loa~ in the 10 ~ c~nditio~, ~nP ~risgo~ 102 ~ p~o~J~dod very late in the power lino ~y~le, for exa~nple at 17~ or 180 ~agreQs.
If the trigg~ 102 1~ ac~l~ra~ed ~t 175 dogr~s in the cycle ~ 'ch~ R~8 powrar reachin~ th~ load is ver~l~ low . As the f lring angl~ is daceasQd rrom 17~ ~e~r~e3 tow~ds~ 5 15 deç~ree~, th~ pow~r applied to the load lncrea~e~.
A zero cro~5ing Bignal llO driv~ ran~ or 112 ~ ~he ~utput o~ ~h~ tran~tor 112, I~Q corre~t~ the mlcrocont~oller chip's timing p~lodlcally to ~n~ur4 that it i~ in ~tep with tha ave~ag4 11ne ~re~uency at 20 the zero c:~0~slnç~ ~oint.
q~h2 Z MRz ~ erens~ 4~11ator 1~0 iY, ~or~ed with tho c:ryf~tal 114, c~pacitC~r~ 116 antl 118 arld r~ ;tor 120 coupled So pin~; 3~ ~nd 39 ~8 shown in ~igUr~ 5 ~ Uao~ depre~ e witch~g 12~ proYide control 25 of the microproce~gor operation~ The u~ar d~pr~ible switcho~ i~clud~ a r8s4t, a mode ~ale~t, manual up and manual down, alarr~ enable, au~o ~im and ~ime ~adjus~ment ~apabilities .
Power iB pro~ided to the tnlaroprl~c~6so~ of 30 Figure 5 by t~e bridge r~tifier oir~ui~ 128 o~ Figllre 4. A diode rQcti~ying brldg~3 128 is ~od t2~rough an ~ola'cion dio~ 130 to ~ ~rolt~o r~ tor 13~.
~hRrgin~ fo~ ~he backuD ~att~ry 134 ia provide~ a~
~oltage ~JA ~r~m tne lnput circui~ Diode6 1~6 a~d 1 3a 33 ACt' ~ a ~urre~t ~t~er$ng circuil: to Gouple th~ batt~ry 134 to the 8ySt:21D if ~he line ~roltag~ go8g down. If th~
line ~rolt~ge y~s down, th~ chip conr.ection~ to YC c ~
1 31 406q to ~ro volt~ hu~ing down the ~ortions o~ th~ clrcll~t whlch u~e a hl~h opera~lng cur~en~, ~uch ns tha ~¢D
reoi~tor network, th~ opt~coupl~r to ths triac circult ~nd th~ likQ. Th~ backup ~at~ery ~olt~ge vl3AT 1 provided by the battory to the mioroaon~ollsr 140, ~aving the baE~ memory. ~he ~a~Rup ~lrcuit al~D
includ~s thel cira~it ~ Fi~uro 7 having a dio~ and a on~ miarof ar~ed capa~itor ~o protect the chip rrom pow~r ~ump~ tl~at could onu~ r~ti~ ope~atior~ 4~ th~a ch~p al~d 10 also to supply ~ r~et pulse RES ~o the Chip when t~e lihe power ~ola~3 down.
Re~errlng to Flgures 4 and 5, th~
mlcrocontroller 14~ ha~ ~een p~rc1~6mo~ 5~pp~y t~CI
powor curv~ to control the tiDIinç~ of th~ tr~ gger pul~e 15 142 to th~ trlac~ math~-tatlaal ~o~rnul~ ~or th~
contr~ r ~ f ol low~
ao V~ 200 ~ ~
load volt~a~e QS~UAl# 'cn i Z ~cu~ed ClVid~d by 20Q3, wh~re tn ls the tim~ ~lnc~ th~ nL eign~l. A~ th~ ti~
~since t~e al~rm (tn) inc~ea~es, up to 26 minutes maxi~u~, tne ~crl~g~ pul~ o th~ tri~cl d~Por~aa~e6- frorn ~pproxin~ately 175 degree3 firing angle ~o apprexima'cely 5 degr~s ~lrlng angle . Tt~e timing o~ the trigger pul E:o ie aloo ~crib~d in rela~ n to ~he pha~e an~le, tha'c is ~he ~iring angle ~ ~he ~rl~c 108 wit~ r~latlon~h~p t~ thOE lin~ volt~ge.
PhaoeAnç~ P~
175.5 ~ .2stn - o.~ tn2 + ~xlo ~4 tn3 ~4) wh~re the phase angle i~ thc ~ngle o~ the 1 i ne vol~age - lOY rrOD I.l to N ~ PLgu~o 4 o.t whi~h ~ tr~ggf2r i~
3ctiv~ted arld tn i3 the time elap~ nce ~he alarm 3S occurre~.
The manual cont~ol ~wi1~che3 122 to the mic:r~con'croller oLe Figur2 ~ ~re defin~d ~ foll~w~:
:~eaet 63top~ ~ha ~uto ~larm or auto dim op-ra~-ion at the llqht le~el ~It th~t moment ~d ~ w~ th~ nuqll contro~9 for ~incr~3~3el' ar~d ~de¢~ea6eH to be u~ed. Mo~ie ~3~3t~3 th~ "ml~de" t~ ith~r (a) alarm ~me abl di~iplayed 6~n th~ l) and a3 ~et by ~he u~r or ~b) real t ~ me ~
di~ ay~d on ~Ae L.CD and ~ounting. Alarm 15n~bie actl~a~3 tho alarm to ~ause th~2 E;iqn~l t9tn~ ~:D b~g~n ene coun~ rrom zero cnw3rd . AUtO Dlm act lv~e~ ~ne au~¢o dim c1p~ratiDn where the lE~el o~ ~e ligh~ at thQ ti~e ~-h~ auto d~m ~u~ton ~ depres~ied begin~ to decrea~e 10 S~llowin~ th~ ~cnt-a fD~ulae until the lighi; 1~
compl~t~ly out~ ~ auto ~ utt~n c;au6s~ the light ~o oporato in th~ oppo~ m~nn~r ~o thL alnr~ nn;7dc ~1D
th~t the light level i~ decr~a~ing base~ on th~ pr~
~o~mulA r~ r th~ln ino~e~l~in~. The Tiw~ ~dju~t E3witCh 15 pe~rmit6 a~iu~tmer~t o~ the ~im~ in the Alana mode~ or re31 t~m~ ~od~ as~ pr~iou~ly ~ us~ed. When th~ tim~3 ad~us~t i~ depre~sed, the ti~e is inarea~e~ in ~inu~es ~nd ln nour~ a~ contrt~llecl by tt~e u~ex ~ when ~ne in~l~at~d tim~ e~u~l~ the de~ired E:et tlme, t~e b ~tton ~ s 20 r~le~od. Proqr~nmin~ o~ man~lal button~ to aocompli~h thic~ aro we~l Xnown in the ~rt.
Flgure 4-g lllu~rat a particular dig~lt~l airaui~ mi~rooont~olle~ ~or r~ irJg th~ inv~:rtlo~
5h~ circuit include~ dig~tal oo~pon~t~ ~uch a~ ~h~
25 mlc~oc~ trolle~r 140 ~In~ ~nnlog co~pon~:nt~ ~uDh n~ tbe lin~ ~oltag~ ~ro~o I.l to N and triac 108. Any o~h~r digital ~;:ircuit cilp~ble o~ perrorming a ~;imi'l ilr ~ ti~n would ~e ~;uitabl~ for u~e in pl~c~ o~ t sht~wn.
The invention may also b~ U od to aid 30 pc3r~:o~, p~icula:~ly an in~ant~ in ~all~ a~l~4p. 5h~
charge on ~apacit~r 44 ~ay b~3 filowly blad o~ through po~n~iometer J,5 by ~oupl~n~ th.l3 othe~ r31de ~f pot~ntlom~t~r 46 to ground through E~ swi~oh. Th~3 u~r m~y ~et: ~he ligh~ to ~e f~lly or part~lly on e~7;d tht~n 3S ~at t~e a~itch to 310wly bleed d~wn capac$tsr 44 through po~ontio~et~r 46. The ir~n'c ~rill G~m~ bly lie i~
bed without havin~ to be afraid o;e the d~rk. Over a 30-29 l 3 1 406q minute to 2-hour period, as determined by the setting of potentiometer 46, the light intensity will slowly decrease using the same circuit and principles as described herein for increasing the light. The infant will fall asleep as the light lowly grows dimmer. The in~ant will be asleep prior to the lamp going out completely and will thus have a gentle and ea~y sleep.
The same light may be used to awaken the infant at a given time the next morning, based on a similar time interval, if desired. The infant is thus allowed to fall asleep without fear. The circuit may also be used by adults, if desired, to ease them into a sleepy state based on changes of light to simulate tha setting of the sun.
While a lamp 26 has been shown as the load, any other load to be smoothly driven may be used. For example, a motor, drill or inductive load or other load may be driven by the circuit of this invention. A
switch to permit the power provided to the load to be rapidly and manually variable as directly controlled by the user may also be provided if desired.
Claims (4)
1. An apparatus for varying the brightness of a light which is adapted to be powered by an AC power supply having zero-crossings, in a nonlinear power level as a function of time, comprising:
a circuit for providing power to said light from the AC power supply;
a zero-crossing sensor means for sensing each zero-crossing of said AC
power supply and outputting a zero-crossing signal at each of said zero-crossings;
a precision timer coupled to the output of said zero-crossing sensor and receiving said zero-crossing signals, said precision timer outputting an oscillating frequency signal having a plurality of zero-crossing points in between each zero-crossing of said AC power supply and at least one of said oscillator zero-crossings occurring simultaneously with said AC power supply zero-crossings;
an electric circuit that generates a trigger pulse at a selected time after saidAC signal zero-crossing, said selected time being variable from a first time after said zero-crossing to a second time after said zero-crossing, said second time occurring more closely after said AC zero-crossing than said first time occurs after said AC zero-crossing, said selected time gradually varying from said first time to said second time after an input signal goes high to cause the AC power supply toincrease in a nonlinear power level as a function of time; and a switching circuit coupled to said electric circuit for causing a switch to turn on and provide power to said light from said trigger pulse output going high until said AC power supply passes through a subsequent zero-crossing to thus control the intensity of said light based on said selected time of said trigger output line going high.
a circuit for providing power to said light from the AC power supply;
a zero-crossing sensor means for sensing each zero-crossing of said AC
power supply and outputting a zero-crossing signal at each of said zero-crossings;
a precision timer coupled to the output of said zero-crossing sensor and receiving said zero-crossing signals, said precision timer outputting an oscillating frequency signal having a plurality of zero-crossing points in between each zero-crossing of said AC power supply and at least one of said oscillator zero-crossings occurring simultaneously with said AC power supply zero-crossings;
an electric circuit that generates a trigger pulse at a selected time after saidAC signal zero-crossing, said selected time being variable from a first time after said zero-crossing to a second time after said zero-crossing, said second time occurring more closely after said AC zero-crossing than said first time occurs after said AC zero-crossing, said selected time gradually varying from said first time to said second time after an input signal goes high to cause the AC power supply toincrease in a nonlinear power level as a function of time; and a switching circuit coupled to said electric circuit for causing a switch to turn on and provide power to said light from said trigger pulse output going high until said AC power supply passes through a subsequent zero-crossing to thus control the intensity of said light based on said selected time of said trigger output line going high.
2. The apparatus according to claim 1 further including a gate circuit coupling said electric circuit to said switching circuit, said gate circuit providing an output signal that goes high when said trigger pulse is generated.
3. The apparatus according to claim 1 wherein said electric circuit includes a microcomputer, said microcomputer having an internal timing clock controlled by said oscillator's zero-crossings to ensure that said timing clock generates pulses whose occurrence is actually positioned relative to said zero-crossing of said AC signal, said microcomputer circuit including a trigger pulse output line on which said trigger pulse is generated.
4. The apparatus according to claim 1 wherein said switching circuit includes a triac having its gate coupled to said electric circuit for causing said triac circuit to turn on and provide power to said light from said trigger pulse output going high.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US22171688A | 1988-07-20 | 1988-07-20 | |
| US07/221,716 | 1988-07-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1314069C true CA1314069C (en) | 1993-03-02 |
Family
ID=22829033
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000606263A Expired - Fee Related CA1314069C (en) | 1988-07-20 | 1989-07-20 | Light source with gradually changing intensity |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1314069C (en) |
-
1989
- 1989-07-20 CA CA000606263A patent/CA1314069C/en not_active Expired - Fee Related
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