HK1097392A - Lighting control device having improved long fade off - Google Patents

Description

Cross reference to related applications for lighting control devices with improved long fade off

The present application claims priority from U.S. patent application No.10/753,035 entitled "Lighting control device Having Improved Long Fade Off", filed on 7/1/2004, the contents of which are incorporated herein by reference.

Technical Field

The present invention relates generally to lighting control devices. More particularly, the present invention relates to a lighting control device that uses a series of fade rates to fade the light intensity level of one or more lamps.

Background

Dimmer switches, i.e., wall-mounted light switches including dimmers, have become increasingly popular, particularly for applications in which it is desirable to accurately control light intensity levels in a particular room. Some known dimmer switches use a variable resistor operated manually to control the switching of a triac (triac), which in turn varies the voltage input to the lamp being dimmed. Such manually operated variable resistor dimmer switches have a number of known limitations. There are some touch activated controllers to address at least some of these limitations.

One such touch actuation controller repeatedly cycles through a range of intensities from dark to light in response to continued touch input. A memory function is provided so that when the touch input is removed, the cycle will stop and the light intensity level at that point in the cycle will be stored in memory. A subsequent short touch input will turn off the light and a further short touch input will turn on the light at the intensity level stored in the memory. While this type of switch is an improvement over manually operated variable resistor dimmer switches, it requires the user to go through a cycle of intensity levels in order to achieve the desired intensity level. In addition, it still lacks the ability to return to the desired intensity level after having been adjusted to full light output. The user must go through the cycle again until he or she finds the desired light intensity level. Also, this type of switch typically does not have the ability to exhibit certain aesthetic effects, such as a gradual fade from one light intensity level to another.

Us patent No.5,248,919 ("the 919 patent") discloses a lighting controller that may include user-actuatable intensity selection means for selecting a desired intensity level between a minimum intensity level and a maximum intensity level, and control switch means for generating control signals indicative of preselected states and intensity levels in response to input from a user. The disclosure of the 919 patent is incorporated herein in its entirety.

The 919 patent also discloses control means for causing at least one lamp to fade: a) fading from an off state to a desired intensity level at a first fade rate when an input from a user causes the switch to close; b) fade from any intensity level to a maximum intensity level at a second fade rate when an input from the user causes both switches to close in rapid succession for a short duration (transition duration); c) fade from the desired intensity level to an off state at a third fade rate when an input from the user causes the single switch to close for a short duration; and d) fade from the desired intensity level to an off state at a fourth fade rate when an input from the user causes the single switch to close for more than a short duration. The control means may cause the lamp to fade from the first intensity level to the second intensity level at a fifth fade rate when the intensity selection means is activated for a time exceeding the short duration.

Fig. 1 depicts a prior art wall station 10 as described in the 919 patent. As shown, the wall station 10 includes a cover 12, an intensity selection actuator 14 for selecting a desired light intensity level for one or more lamps controlled by the station, and a control switch actuator 16. Actuation of the upper portion 14a of actuator 14 increases or raises the light intensity level, while actuation of the lower portion 14b of actuator 14 decreases or lowers the light intensity level. The wall station 10 may also include an intensity level indicator, for example, in the form of a plurality of light sources 18, which light sources 18 may be, for example, Light Emitting Diodes (LEDs). By illuminating a selected one of the light sources 18, the illuminated light source location within the array may provide a visual indication of the light intensity level of the lamp or lamps being controlled.

Here, the example fade rates and fade rate profiles (profiles) shown in the 919 patent are reproduced as in FIGS. 2A-2D. Fig. 2B shows a first fade rate at which the lamp is dimmed from an off state to a desired intensity level. The first gradual change speed from "off" to the desired intensity level is labeled as reference numeral 40. Fig. 2B shows the ramp rate in seconds from a plot of normalized (normalized) light intensity level from "off" to 100% versus time. As shown, fade rate 40 may fade from "off" to 100% in approximately 3.5 seconds, i.e., at a rate of approximately + 30% per second. This fade rate is used when the lighting control device 10 of the present invention receives a single tap control switch actuator 16 input by the user and the controlled light was previously off. The fade rate may also (but is not required to) be used when the user selects a desired intensity level by actuating the intensity selection actuator 14. Thus, when the upper portion 14a of the actuator 14 is actuated by the user, the lamp 20 will brighten from one intensity level to another at the fade rate 40.

Similarly, fig. 2C shows a fade rate 42 at which the lamp 20 will fade from one intensity level to another when the controlled lamp has been turned on to tap the actuator 16, or when the lower portion 14b of the actuator 14 is actuated by the user. Fade rate 42 is shown to be the same as fade rate 40, but in opposite sign, and takes about 3.5 seconds from 100% to "off," i.e., a fade rate of about 30% per second. It should be understood, however, that the exact fade rates are not critical, and that fade rates 40 and 42 may be different.

Fig. 2A shows a second fade rate 44 at which the lamp 20 is dimmed to 100% when the lighting control device 10 receives two consecutive taps of the control switch actuator 16 from the user input. As described above, two taps on actuator 16 cause lamp 20 to fade from its then-current light intensity level toward 100%, or full on. Fade rate 44 may be substantially faster than first fade rate 40, but not so fast as to be substantially instantaneous. One example of fade rate 44 is approximately + 66% per second. If desired, the fade rate 44 can begin after a short time delay (such as 0.3 seconds), or a slower fade rate 46 can be added during this interval.

The "hold" input at actuator 16 causes lamp 20 to fade from its then-current intensity level to off at a third fade rate 48, as shown in fig. 2D. Fade rate 48 may be much slower than any of the previously shown fade rates. Fade rate 48 may also not be constant, but may vary depending on the then-current intensity level of lamp 20. However, the fade rate may be such that the lamp 20 will fade from its then-current intensity level to off for all initial intensity levels in approximately the same amount of time. For example, if it is desired that the lamp 20 fade to off in about ten seconds (to give the user time to, for example, pass through a room before the lights are extinguished), a fade rate of about 10% per second may be used if the then-current intensity level of the lamp 20 is 100%.

On the other hand, if the then-current intensity level of lamp 20 is only 35%, the fade rate may be only 3.5% per second, so that lamp 20 will not reach full shut-down until the desired ten seconds. Additionally, if desired, a slightly faster fade rate 50 may be used within the first approximately half second of the fade in order to give the user immediate feedback to determine that the fade has begun. A suitable fade rate 50 may be about 33% per second. A similarly faster fade rate 52 may also be used near the end of the fade so that the lamp 20 extinguishes quickly after fading to the low intensity level. Thus, after about ten seconds of fading down at a relatively slow rate, the lamp 20 will fade to off in the remaining manner in about one second. If fast initial and final fade rates are used, the intermediate fade rate must be slowed down to achieve the same fade time.

However, as shown in fig. 2D, at lower initial intensity levels, the intermediate fade rate may be zero (constant light output), and at even lower initial intensity levels, the lamp may fade off during the initial fast fade. Thus, at low light intensities (e.g., below about 20%), the control device tends to turn the lamp off before a long fade off is initiated (i.e., before a single switch closure is detected for more than a short duration). It would be desirable if such a light controller could initiate a long fade off from any light intensity.

Disclosure of Invention

The present invention relates to a lighting control apparatus that, upon determining that a switch controller has been activated, causes a light intensity level of at least one lamp to fade at a first fade rate based on its initial intensity. In an exemplary embodiment, a lighting control device may include a microcontroller and a user-actuatable switch controller operatively connected to the microcontroller.

When the switch controller is initially activated, the microcontroller causes the light intensity level of the at least one lamp to fade at a first fade rate. The microcontroller causes the light intensity level of the at least one lamp to fade at a second fade rate for a predetermined long fade time if the microcontroller determines that the switch controller has been actuated for at least the predetermined actuation time.

The first fade rate is based on a predetermined fade off time, which represents the time allotted for fading the light intensity level of the at least one lamp from its initial intensity level to zero. To prevent the light intensity level from fading to off before the start-up time elapses, the fade-off time may be defined to be longer than the start-up time. The second fade rate may be slower than the first fade rate and may have an exponential fade profile.

After the long fade time has elapsed, the microcontroller causes the light intensity level of the at least one lamp to fade to off at a third fade rate. The third fade rate may be a predetermined rate at which the microcontroller causes the light intensity level to fade from 100% to zero.

Drawings

In the drawings, like numbers indicate like elements:

fig. 1 depicts a prior art wall station;

2A-2D depict exemplary fade rates and fade rate profiles in a prior art lighting control system;

fig. 3 depicts a wall station 100 embodying a lighting control apparatus in accordance with the present invention;

FIG. 4 is a simplified block diagram of an example circuit for a lighting control apparatus according to the present invention;

5A-5D depict a scheme for comparing the fade profile of a lighting control device according to the present invention with that of a typical prior art lighting control device; and

fig. 6 is a flowchart showing the operation of the control apparatus according to the present invention.

Detailed Description

Fig. 3 depicts a wall station 100 embodying a lighting control apparatus in accordance with the present invention. The wall station 100 includes a front cover 102, an intensity selection actuator 104 for selecting a desired light intensity level of the lamp to be controlled by the station, and a control switch actuator 106. The front cover 102 need not be limited to any particular form, and is preferably of a type suitable for mounting to a conventional wall box typically used for mounting lighting control devices. Actuators 104 and 106 are likewise not limited to any particular form, and may be any suitable structure that allows manual actuation by a user.

Actuator 104 may control, for example, a rocker switch, but may also control, for example, two separate push-button switches without departing from the invention. The switches controlled by the actuators 104 may be wired directly to the control circuitry described below, or may be connected to the control circuitry by extended electrical wiring, infrared wiring, radio frequency wiring, power line carrier wiring, or otherwise. Likewise, the switches controlled by actuator 106 may also be wired directly to the control circuitry, or connected to the control circuitry by extended electrical wiring, infrared wiring, radio frequency wiring, power line carrier wiring, or otherwise. Actuators 104 and 106 may be connected to the respective switches in any convenient manner.

Actuator 106 may control, for example, a button-type switch, such as a toggle button, but may also be touch-controlled or any other suitable type. Actuation of upper portion 104a of actuator 104 increases or raises the light intensity level, while actuation of lower portion 104b of actuator 104 decreases or lowers the light intensity level.

The wall station 100 may include an intensity level indicator in the form of a plurality of light sources 108. The light source 108 may, but need not, be a Light Emitting Diode (LED) or the like. Light sources 108 may sometimes be referred to herein as LEDs, but it should be understood that such reference is for ease of description of the invention and is not intended to limit the invention to any particular type of light source. The light sources 108 may be arranged in an array representing a range of light intensity levels of the lamp or lamps being controlled, from a minimum intensity level, preferably the lowest visible intensity (but which may be zero, or "fully off"), to a maximum intensity level (which is typically 100%, or "fully on")

When the lamp or lamps being controlled are turned on, by illuminating a selected one of the light sources 108 according to the light intensity level, the position of the illuminated light source within the array will provide a visual indication of the light intensity associated with that range. For example, seven LEDs are shown in a linear array in fig. 3. Illuminating the uppermost LED in the array will give an indication that the light intensity level is at or near the maximum. Illuminating the center LED will give an indication that the light intensity level is at about the midpoint of the range. Any convenient number of light sources 108 may be used, and it will be appreciated that a greater number of light sources in the array will produce a better gradation between intensity levels within the range that matches this.

When the lamp or lamps being controlled are turned off, all light sources 108 may be constantly illuminated at a low illumination level, while the LEDs representing the current intensity level in the on state are illuminated at a higher illumination level. This enables the array of light sources to be more readily perceived by the human eye in dark environments, for example, which helps the user find the position of the switch in a dark room in order to activate the switch to control the lights in the room, but still provides sufficient contrast between the level indicating LED and the remaining LEDs so that the user can perceive the relative intensity level at a glance.

The wall station 100 may include a standard back box (back box)110, a plurality of high voltage wires 112, which high voltage wires 112 may be hot, neutral, and dimmed hot (dimmed hot) as described below, and a plurality of low voltage wires 114 that may be used to provide low voltage communication to the wall station 100.

Fig. 4 is a simplified block diagram of an example circuit for a lighting control apparatus according to the present invention. The circuitry schematically shown in fig. 4, or any portion thereof, may be contained within a standard back box, such as back box 110.

The lamp set 120, which may include one or more lamps, is connected between the hot and neutral terminals of a standard AC (alternating current) power supply at 120V, 60 Hz. Lamp set 120 may include one or more incandescent lamps each rated at, for example, between 40W and several hundred watts. It should be understood that the lamp set may include other loads such as an Electrical Low Voltage (ELV) or a Magnetic Low Voltage (MLV), for example, in addition to or in place of an incandescent lamp.

The banks 120 of lamps may be connected by a solid state switching device 122, which solid state switching device 122 may include one or more triacs, which may be thyristors or similar control devices. Conventional dimming circuits typically use triacs to control the conduction of line current through the load, allowing a predetermined conduction time, and to control the average electrical power of the lamp. One technique for controlling the average electric power is forward phase control. In forward phase control, a switching device, which may comprise a triac for example, is turned on at some point within each AC line voltage half-cycle and remains on until the next current zero crossing. Forward phase control is often used to control the power applied to a resistive or inductive load, which may be, for example, a magnetic lighting transformer.

Since the triac device can only be selectively switched on, a Field Effect Transistor (FET), such as a MOSFET (metal oxide semiconductor FET), for example, may be used for each half cycle of the AC line input when the off phase is selectable. In reverse phase control, the switch is turned on when the voltage of the AC line voltage crosses zero and turned off at some point within each half-cycle of the AC line current. Reverse phase control is often used to control the power applied to a capacitive load, such as an electronic transformer connected to a low voltage lamp.

The switching device 122 has a control input, or gate input 124, connected to a gate drive circuit 126. Those skilled in the art will appreciate that a control input on gate input 124 will cause switching device 122 to conduct or insulate, which in turn controls the power provided to lamp set 120. The driver circuit 126 provides a control input to the switching device 122 in response to a command signal from the microcontroller 128. FET protection circuitry 136 may also be provided. Such circuits are well known and need not be described herein.

The microcontroller 128 may be, for example, any Programmable Logic Device (PLD), such as a microprocessor or an Application Specific Integrated Circuit (ASIC). The microcontroller 128 generates command signals to the LED control circuit 129, which LED control circuit 129 controls the array of light sources 108. Inputs to microcontroller 128 are received from AC line zero crossing detector 130 and signal detector 132. Power to the microcontroller 128 is provided by a power supply 134. A memory 135, such as an EEPROM, for example, may also be provided.

Zero-crossing detector 130 determines the zero-crossing points of the incoming 60Hz AC waveform from the AC power source. The zero crossing information is provided as an input to the microcontroller 128. The microcontroller 128 establishes gate control signals to operate the switching device 122 to provide voltage from the AC power source to the lamp set 120 at predetermined times relative to the zero-crossing points of the AC waveform. The zero-crossing detector 130 may be a conventional zero-crossing detector and need not be described in further detail herein. In addition, the timing of the transition start pulse relative to the zero crossing of the AC waveform is also well known and need not be described further.

Signal detector 132 receives as input a switch close signal from a toggle switch controlled by switch actuator 106, and a raise switch and a lower switch controlled by upper portion 104a and lower portion 104b, respectively, of intensity selection actuator 104.

The signal detector 132 detects when the switch is closed and outputs a signal representative of the state of the switch as an input to the microcontroller 128. The signal detector 132 may be any form of conventional circuitry for detecting the switch closure and converting it to a suitable form as an input to the microcontroller. Those skilled in the art will understand how to construct the signal detector 132 without further explanation here. The microcontroller 128 determines the duration of the closure in response to input from the signal detector 132.

A preprogrammed "raise light level" routine in the microcontroller 128 is initiated, such as by a user depressing actuator 104a to close a raise switch, and causes the microcontroller 128 to reduce the off (i.e., non-conducting) time of the switching device 122 via the gate drive circuit 126. The reduction in off-time increases the amount of time the switching device 122 is in conduction, which means that a greater proportion of the AC voltage from the AC input is diverted to the lamp 120. Thus, the light intensity level of the lamp 120 may be increased. The off-time is reduced as long as the raise switch remains closed. As soon as the raise switch is opened, for example by the user releasing actuator 104a, the routine in the microcontroller stops and the off time remains constant.

In a similar manner, a lower switch is closed, such as by a user depressing actuator 104b, to initiate a preprogrammed "lower light level" routine in microcontroller 128 and cause microcontroller 128 to increase the off time of switching device 122 via gate drive circuit 126. The increase in off-time reduces the amount of time the switching device 122 is in conduction, which means that a smaller proportion of the AC voltage from the AC input is diverted to the lamp 120. Thus, the light intensity level of the lamp 120 may be reduced. The off-time is increased as long as the lowering switch remains closed. As soon as the lower switch is opened, for example by the user releasing actuator 104b, the routine in microcontroller 128 stops and the off-time remains constant.

The actuation switch is closed in response to actuation of actuator 106 and remains closed for as long as actuator 106 is depressed. The signal detector 132 provides a signal to the microcontroller 128 indicating that the activation switch has been closed. The microcontroller 128 determines the length of time the activation switch is closed. The microcontroller 128 is able to distinguish between a closure of the activation switch for only a short duration (i.e., shorter than the actuator hold time described below) and a closure of the activation switch for more than a short duration (i.e., longer than or equal to the actuator hold time described below). Thus, the microcontroller 128 is able to distinguish between a "tap" of the actuator 106 (i.e., a short duration closure) and a "hold" of the actuator 106 (i.e., a closure that exceeds the short duration).

The microcontroller 128 is also capable of determining when the start switch is closed multiple times in a short time sequence. That is, the microcontroller 128 is able to determine the occurrence of two or more rapid consecutive taps.

When the starting switch is activated, different closures of the starting switch will result in different effects depending on the state of the lamp 20. A single tap of the actuator 106, i.e., a short closure of the actuator switch, will result in a fade to off when the lamp 120 is at an initial, non-zero intensity level. The operation of the controller in these cases is described in detail below. Two taps in rapid succession will begin a routine in the microcontroller 128 that causes the lamp 120 to fade from an initial intensity level to a preset desired intensity level at a preprogrammed fade rate. The operation of the controller in these cases is described in detail in the 919 patent. The "hold" of actuator 106, i.e., the closure of the actuator switch beyond a short duration, begins a routine of microcontroller 128 that gradually ramps from an initial intensity level to off over an extended period in a predetermined ramp rate sequence. The operation of the controller in these cases is described in detail below.

When the lamp 120 is off and the controller 128 detects a single tap or closure for more than a short duration, a preprogrammed routine is started in the microcontroller 128 that causes the light intensity level of the lamp 120 to fade from off to a preset desired intensity level at a preprogrammed fade rate. Two taps in rapid succession will begin the routine in the controller 128 causing the light intensity level of the lamp 120 to fade from off to full on at a predetermined rate. The fade rates may or may not be the same. The operation of the controller under each of these conditions is described in detail in the 919 patent.

In addition, another set of toggle buttons, raise button, and lower button may be provided at remote locations within a separate wall box, as schematically illustrated by the dashed lines in FIG. 4. The remote toggle, raise and lower buttons, and the associated toggle, raise and lower switches, function in correspondence with the actuation button 106, raise button 104a, lower button 104b, and their respective switches. Remote circuitry 133 may be provided to contact a remote wall station.

An example scheme of dimming using the lighting control apparatus according to the present invention will now be described in conjunction with fig. 5A-5D. Fig. 5A-5D depict a scheme for comparing the fade profile (shown in solid lines) of a lighting control device according to the present invention with the fade profile (shown in dashed lines) of a typical prior art lighting control device. Specific terms used in the following description are defined herein as follows.

The "hold time" or "button hold time" or "actuator hold time" is the amount of time that an actuator (e.g., a toggle button) must be actuated (e.g., pressed) so that a "hold" effect is produced (i.e., for the microcontroller to recognize "hold" as described above). In an exemplary embodiment of the invention, the default value for the actuator hold time may be about 0.5 seconds. It is contemplated that the actuator hold time will be between about 0.01 and about 2.56 seconds for maximum application, although it should be understood that the actuator hold time may be chosen to be any value suitable for the particular application.

The "fade off time" is a predetermined amount of time allotted for the controller to cause the lighting to fade from its current light intensity level to off. The fade off time is used to calculate the fade rate to be used from the time the initiator is initially activated until the hold time elapses. According to the present invention, the fade off time is defined to be longer than the hold time so that the controller does not fade the lighting off before the hold time elapses. In an exemplary embodiment of the invention, the default value for the fade off time may be about 2.25 seconds. It is contemplated that the fade off time will be between about 0 and about 64 seconds for maximum application, although it should be understood that the fade off time can be chosen to be any value suitable for a particular application.

The "long fade time" is the amount of time for the controller to fade the lighting according to a second fade profile, preferably a slower, e.g. exponential, fade profile, after the hold time has elapsed. In an exemplary embodiment of the present invention, the default value for the long fade time is 10 seconds. It is contemplated that the long fade time will be between about 0 seconds and about 4 hours for maximum application, although it should be understood that the long fade time can be chosen to be any value suitable for the particular application.

The "fade off speed" is a predetermined speed at which the controller causes the lighting to fade to off. After the long fade time expires, the fade off speed is used. In an exemplary embodiment of the invention, the default value for the fade off speed may be the speed required to cause the illumination to fade from 100% intensity to off in about 2.75 seconds. It is contemplated that the time allotted for fading from fully on to fully off may be between about 0 to about 64 seconds for maximum application, although it should be understood that the fade off rate may be chosen to be any value suitable for a particular application.

The "LED flash speed" is the speed at which intensity level indicator 108 flashes during a long fade time. In an exemplary embodiment of the invention, the default value for the LED flash speed may be 2 Hz. It is contemplated that the flash rate may be between about 0.2 and about 50Hz for maximum application, although it should be understood that the flash rate may be chosen to be any value suitable for a particular application.

An exemplary dimming scheme utilizing a lighting control apparatus according to the present invention may be generally described as follows. The user presses the toggle button 106 when the light intensity level of at least one of the lights is non-zero. The microcontroller detects the switch closure that occurs and causes the light intensity level to fade at a first fade rate based on the fade off time, i.e., the predetermined amount of time for the controller to cause the lighting to fade from its current light intensity level to off.

If the user continues to press the toggle button 106 until the button hold time elapses, the microcontroller interrupts the ramping at the first ramp rate and causes the light intensity level to ramp at a second ramp rate (e.g., an exponential ramp rate). At this point, the long fade time begins and the intensity level indicator 108 begins to flash.

After the long fade time expires, the microcontroller interrupts the fade of the second fade rate and begins to fade the light intensity level at a third fade rate (i.e., a fade off rate), which is a predetermined rate at which the controller is programmed to fade the light intensity level to zero. The intensity level indicator stops flashing.

Fig. 5A depicts a scenario in which the light intensity level is initially relatively high (e.g., 100%) and the user presses and holds the toggle button for at least the button hold time. From the time the toggle button is initially pressed until the button hold time elapses, the controller causes the light intensity level to fade at a first fade rate based on the fade off time (and, thus, the initial light intensity level of the at least one lamp). In particular, the first fade rate may be the rate required to fade the lighting from the initial intensity level to off during the fade off time.

The steep slope of the fade off time allows the user to visually see the change in light intensity. At high intensities, a more significant change in light intensity may be desirable so that the user's eyes can perceive the change. The user immediately sees the result of the toggle button press.

After the button hold time has elapsed, the controller interrupts the fade at the first fade rate and then causes the light intensity level to fade at the second fade rate during the long fade time. In an exemplary embodiment of the present invention, the second fade rate may be an exponential fade rate that is slower than the first fade rate. Thus, the user can detect the start of a long fade time, since becoming exponentially faded immediately results in a less noticeable change in light intensity level than fading based on the first fade rate.

After the long fade time has elapsed, the controller interrupts the fade of the second fade rate and causes the light intensity level to fade to off at a third fade rate (e.g., a fade off rate).

By contrast, prior art systems cause the light intensity level to fade at the fade off rate from the time the toggle button is initially pressed until the button hold time expires. Since the first fade rate based on the fade off time is greater in this scheme than the fade rate employed in prior art systems, in the system of the present invention the long fade time starts with illumination at a lower light intensity level than in prior art systems.

Fig. 5B depicts a scenario in which the light intensity level is initially relatively low (e.g., 25%) and the user presses and holds the toggle button for at least the button hold time. From the time the toggle button is initially pressed until the button hold time elapses, the controller causes the light intensity level to fade at a first fade rate based on the fade off time. In particular, the first fade rate may be a rate at which the lighting is faded from an initial level to off during the fade off time. The shallow slope of the fade off time prevents the light intensity from decreasing significantly or even turning off before the long fade time is initiated.

After the button hold time has elapsed, the controller interrupts the fade at the first fade rate and then causes the light intensity level to fade at the second fade rate during the long fade time. In an exemplary embodiment of the present invention, the second fade rate may be an exponential fade rate that is slower than the first fade rate. It should be understood that any fade profile may be selected for the second fade rate without departing from the scope of the invention

The scope of the invention.

After the long fade time has elapsed, the controller interrupts the fade of the second fade rate and causes the light intensity level to fade to off at a third fade rate (e.g., a fade off rate). It should be understood that any fade rate may be selected as the third fade rate without departing from the scope of the invention.

By contrast, prior art systems cause the light intensity level to fade at the fade off rate from the time the toggle button is initially pressed until the button hold time expires. Since the first fade rate based on the fade off time in this scheme is slower than the fade rate employed in prior art systems, the long fade time in the system of the present invention starts with illumination at a higher light intensity level than in prior art systems.

Fig. 5C depicts a scenario in which the light intensity level is initially relatively high (e.g., 100%) and the user presses and releases the toggle button before the button hold time elapses. From the time the toggle button is initially pressed until the time the toggle button is released, the controller causes the light intensity level to fade at a first fade rate based on the fade off time. In particular, the first fade rate may be a rate at which the lighting may fade from an initial intensity level to off during the fade off time. After the button is released, the controller interrupts the fade at the first fade rate and causes the light intensity level to fade at a second fade rate (i.e., fade off rate).

By contrast, prior art systems cause the light intensity level to fade at the fade off rate from the time the toggle button was initially pressed.

Fig. 5D depicts a scenario in which the light intensity level is initially relatively low (e.g., 25%) and the user presses and releases the toggle button before the button hold time elapses. From the time the toggle button is initially pressed until the time the button is released, the controller causes the light intensity level to fade at a first fade rate based on the fade off time. In particular, the first fade rate may be a rate at which the lighting is faded from an initial level to off during the fade off time. After the toggle button is released, the controller interrupts the fade of the first fade rate and causes the light intensity level to fade at a second fade rate (i.e., a fade off rate).

By contrast, prior art systems cause the light intensity level to fade at the fade off rate from the time the toggle button was initially pressed. It should be appreciated that in such prior art systems, if the initial intensity level is low enough, the illumination will fade to off before the button hold time has elapsed. In the system according to the invention, the fade-off time (and, therefore, the first fade rate) is optionally such that the light intensity level does not fade to off at least until the button hold time has elapsed.

Fig. 6 is a flow chart illustrating the operation 600 of the control device according to the present invention. Such operations may be implemented, for example, by a software program executing on a microcontroller. Such a program may also exist as a set of computer executable instructions stored on any computer readable medium such as a computer hard disk, a removable magnetic medium, a magnetic tape, a compact disk, a floppy disk, and the like. The operation 600 begins at step 602 where it is determined that the toggle button has been pressed when the light intensity level is non-zero (i.e., when the light is turned off).

At step 604, it is determined whether the fade off time is "within range," i.e., whether the fade off time is longer than the button hold time and shorter than (or equal to) a predetermined maximum fade off time. If it is determined that the fade off time is not within the range, then the controller causes the lighting to fade to off at the fade off rate in step 606, and the program exits at step 608.

If, at step 604, it is determined that the fade off time is within the range, then, at step 610, an initial dimming increment, Δ D, is calculated based on the fade off time_i. Closing time T by predetermined fade-out_FDivided by a preprogrammed intensity update period T_UGiven that the intensity will be at a level D from the initial intensity level_iFade to the number of intensity updates that occur during off. Thus, the dimming increment Δ D_iCan be calculated as Δ D_i＝(T_U*D_i)/T_F. Intensity update period T_UAn example of (c) may be about 10 ms.

At step 612, the current level D is increased by the dimming increment Δ D_iAnd (6) updating. That is, D- > D- Δ D_i. In step 614, the amperage level D is converted to a corresponding switching device transition time t. In step 616, the gate control signal is set to transition at transition time ttransition. At step 618, the microcontroller sends a gate control signal to the gate drive circuit, which in turn enables or disables the switching device from conducting。

Step 620, the program loops until the intensity update period T is determined_UHave been in the past. At step 622, the intensity update period timer is restarted. In step 624, a determination is made as to whether the button hold time has elapsed. If not, the process returns to step 612 to still employ the first fade rate such that the amperage level is updated again.

If, at step 624, it is determined that the button hold time has elapsed, then at step 626, it is determined whether the long fade time has elapsed. If not, at step 628, the dimming delta Δ D for long fade off₁According to Δ D₁A (D-1)/N calculation, where N is a predetermined scalar set to produce a slow fade rate (e.g., N1024). The value "1" may be subtracted to ensure that the illumination remains on even if the amperage level D is 1%.

At step 630, the current level D is increased by the dimming increment Δ D₁And (6) updating. That is, D- > D- Δ D₁. At step 632, the amperage rating D is converted to a corresponding switchgear transition time t. In step 634, the gate control signal is set to transition at transition time ttransition. At step 618, the microcontroller sends a gate control signal to the gate drive circuit. In step 620, the program loops until the intensity update period T is determined_UHave been in the past.

If, at step 626, it is determined that a long fade time has elapsed, then at step 636, the lighting fades to off at a preprogrammed fade off rate. The routine exits at step 638.

Thus, an improved lighting control apparatus has been described that causes the light intensity level of at least one lamp to fade at a fade rate that is based on its initial intensity when the switch controller is activated. It should be understood that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof, and accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.

Claims (23)

1. A lighting control device for controlling a light intensity level of at least one lamp, the at least one lamp having an initial light intensity level, the lighting control device comprising:

a microcontroller; and

a user operatively connected to the microcontroller may actuate a switch controller,

wherein when the switch controller is activated, the microcontroller causes the light intensity level of the at least one lamp to fade at a first fade rate, the first fade rate being based on a predetermined fade off time, the fade off time being represented as a duration allotted for fading the light intensity level of the at least one lamp from an initial intensity level to off, and

wherein upon determining that the switch controller has been actuated for at least a predetermined actuator hold time, the microcontroller causes the light intensity level of the at least one lamp to fade at a second fade rate.

2. The lighting control device of claim 1, wherein the fade off time is defined to be longer than the actuator hold time.

3. The lighting control device of claim 1, wherein the microcontroller causes the light intensity level of the at least one lamp to fade at a second fade rate for a predetermined long fade time.

4. The lighting control device of claim 3, wherein after the long fade time has elapsed, the microcontroller causes the light intensity level of the at least one lamp to fade to off at a third fade rate.

5. The lighting control device of claim 1, wherein the second fade rate is slower than the first fade rate.

6. The lighting control device of claim 1, wherein the second fade rate has an exponential fade profile.

7. The lighting control device of claim 4, wherein the third fade rate is a predetermined rate at which the microcontroller is programmed to fade the light intensity level from 100% to zero over a predetermined amount of time.

8. The lighting control device of claim 1, wherein upon determining that the switch controller has been activated for only a short duration, the microcontroller causes the light intensity level of the at least one lamp to fade to off at a third fade rate.

9. A lighting control device for controlling a light intensity level of at least one lamp, the at least one lamp having an initial light intensity level, the lighting control device comprising:

a microcontroller; and

a user operatively connected to the microcontroller may actuate a switch controller,

wherein the microcontroller causes the light intensity level of the at least one lamp to fade at a first fade rate when the switch controller is actuated and causes the light intensity level of the at least one lamp to fade at a second fade rate when it is determined that the switch controller has been actuated for at least a predetermined actuator hold time,

wherein the first fade rate is based on a predetermined fade off time that is longer than a predetermined actuator hold time.

10. A lighting control device for controlling a light intensity level of at least one lamp, the at least one lamp having an initial light intensity level, the lighting control device comprising:

a microcontroller; and

a user operatively connected to the microcontroller may actuate a switch controller,

wherein upon determining that the switch controller has been activated, the microcontroller causes the light intensity level of the at least one lamp to fade at a fade rate that is based on an initial intensity level of the at least one lamp.

11. A method for controlling a light intensity level of at least one lamp, the at least one lamp having an initial light intensity level, the method comprising:

determining that a switch activator has been activated; and

the light intensity level of the at least one lamp is caused to fade at a first fade rate that is based on the initial intensity level of the at least one lamp.

12. The method of claim 11, wherein the first fade rate is based on a predetermined fade off time, the fade off time representing a duration allotted for fading the light intensity level of the at least one lamp from an initial intensity level to off.

13. The method of claim 11, further comprising:

causing the light intensity level of the at least one lamp to fade at a second fade rate upon determining that the switch controller has been actuated for at least a predetermined actuator hold time.

14. The method of claim 13, wherein the first fade rate is based on a predetermined fade off time that is longer than a predetermined actuator hold time.

15. The method of claim 13, further comprising:

the light intensity level of the at least one lamp is faded at a second fade rate for a predetermined long fade time.

16. The method of claim 15, further comprising:

after the long fade time has elapsed, fading the light intensity level of the at least one lamp to off at a third fade rate.

17. The method of claim 13, wherein the second fade rate is slower than the first fade rate.

18. The method of claim 13, wherein the second fade rate has an exponential fade profile.

19. The method of claim 16, wherein the third fade rate is a predetermined rate for fading the light intensity level from 100% to zero over a predetermined amount of time.

20. The method of claim 13, further comprising:

causing the light intensity level of the at least one lamp to fade to off at a third fade rate upon determining that the switch controller has been actuated for only a short duration.

21. The method of claim 20, wherein the third fade rate is faster than the second fade rate.

22. A computer-readable medium having stored thereon computer-executable instructions for performing a method for controlling a light intensity level of at least one lamp, the at least one lamp having an initial intensity level, the method comprising:

determining that a switch activator has been activated; and

the light intensity level of the at least one lamp is caused to fade at a first fade rate that is based on the initial intensity level of the at least one lamp.

23. A lighting control device for controlling a light intensity level of at least one lamp, the at least one lamp having an initial light intensity level, the lighting control device comprising:

a microcontroller; and

a user operatively connected to the microcontroller may actuate a switch controller,

wherein upon determining that the switch controller has been activated, the microcontroller causes the light intensity level of the at least one lamp to fade at a first fade rate that is based on an initial light intensity level of the at least one lamp, and

wherein upon determining that the switch controller has been actuated for only a single short duration, the microcontroller causes the light intensity level of the at least one lamp to fade to off at a second fade rate, an

Wherein upon determining that the switch controller has been actuated for two consecutive short durations, the microcontroller causes the light intensity level of the at least one lamp to fade from the initial intensity level to a preset desired intensity level at a third fade rate, an

Wherein upon determining that the switch controller has been actuated for more than a short duration, the microcontroller causes the light intensity level of the at least one lamp to fade to off in a predetermined sequence of fade rates.