Electric Lamp and Time Dependent Illumination Control

Technical Field

This invention relates to electric lamps and particularly to a novel and improved electric lamp and illumination control which alters the lamp illumination automatically over a selected period of time. Background Art

Lamps or lights are either on or off. Small children are scared by the light being turned off at bedtime, yet parents cannot leave the light on all night.

Night lights provide a partial solution, but are often not bright enough to assuage the fear of a small child, They must remain at a constant illumination for the entire night and provide ineffectual illumination for the child's needs.

Dimmers provide another partial solution. However, a dimmer is manually operable to dim the light illumination in a short transition interval determined by the manual motion of the operator, This is inconvenient, for example, for an elderly person who wants full illumination when they go to bed, but a lower illumination later.

The use of a simple timer is unsatisfactory as it merely turns the light on or off and does not provide dimming action. In addition, a timer must be preset to a certain time which may vary from day to day, as in bedtime in the foregoing example.

SUBSTITUTE SHEET

Both of these groups (small children and the elderly) are literally left in the dark when it is time to go to bed. The population does not have a means of automatically decreasing illumination.

The foregoing discussion also applies to applications where it is desired to brighten the lamp illumination. For example, closing time in dimly lit places such as restaurants is often signalled by manually flashing the lights at a brighter intensity. It would be desirable to have the illumination brighten gradually over a period of time in such cases.

Disclosure of Invention

The present invention is embodied in an improvement for an electric lamp having a light bulb adapted to be illuminated by an electric current. The improvement is characterized by an illumination control which is connectable in circuit with the bulb and operable to change the current progressively during a selected illumination change time interval in a manner to gradually change the illumination intensity of the bulb from a first to a second level of intensity. The illumination control includes a timer which is selectable to set an illumination change time interval and a current changer which coacts with the timer to progressively change the current.

The timer is a first means which stores energy and then releases the stored energy over the time interval. The current changer is a second means that responds to the release of

SUBSTITUTE SHEET

energy to progressively change the illumination by slowly changing the current over the time interval.

Where the first intensity level is higher than the second level, the illumination control acts to dim the illumination. On the other hand, where the first intensity level is lower than the second level, the illumination control acts to brighten the illumination.

The first means is an element having a manually rotatable shaft which acts to store the energy of the rotation in a spring and a further shaft which coacts with the spring to slowly rotate during the release of the stored energy. The second means includes a rheostat driven by the rotation of the further shaft to progressively change the rheostat impedance such that the electric current is progressively changed and the illumination intensity is progressively changed over the time interval.

There are several advantages of the present invention. The ability to automatically decrease lamp illumination over a selected period of time allows children to fall asleep more readily. This takes advantage of a child's ability adapt to gradual darkness. By slowly decreasing the illumination, children will not perceive the evolving darkness as abruptly as with a traditional on/off device. Children's eyes are able to adjust to darkness quicker than adult's eyes. Children's eyes ar much more efficient with available light than adults' eyes as well. A practical proof of this is going into a darkened movie theater with a child who can instantly

SUBSTITUTE SHEET

spot empty seats, while an adult is still trying to see something in the darkness.

Another advantage of the invention is to provide users the ability to have a light on if they need illumination to fall asleep. Rather than falling asleep and having to get up and turn off the bright light , the light will already have decreased to the illumination of a night light, and contribute to an uninterrupted rest. People who are more comfortable falling asleep this way include those whose spouses are absent from the house during the regular sleep time. The light may provide reassurance to the mates who are accustomed to their spouses being relatively close. The invention provides sufficient illumination during the beginning of the sleep cycle, and decreases output automatically, again allowing the user to remain undisturbed in bed.

Yet another advantage is to allow elderly people the time and light to prepare for retiring to bed and actually having the light on full illumination as they find their way to their rooms. The light then decreases gradually until the illumination is that of a night light.

Still another advantage is to reduce electrical energy costs by reducing the power input requirements of the lamp. The user of this device will not leave a light on all night and all day at full power, as the lamp automatically dims during the first forty-five minutes of operation. Rather than leaving a light on all night at full power, this invention reduces the energy used to a fraction of full power requirements.

SUBSTITUTE SHEET

Further objects and advantages of the present invention will become apparent from a consideration of the drawings and ensuing description. Brief Description of Drawings

Figure 1 is a block diagram of an improved electric lamp and illumination control embodying the invention;

Figure 2 is a plan view of an exemplary timer dial surface for the timer of the Figure 1 embodiment; and

Figure 3 is a circuit diagram in part and a block diagram in part of an exemplary current control circuit useful in the Figure 1 embodiment. Best Mode for Carrying out the Invention

The present invention is capable of use in either illumination dimming or brightening applications. However, by way of example and completeness of description, the invention will be described as an embodiment for a dimming application.

Referring to Figure 1 , an electric lamp 20 is shown symbolically as having a lamp switch 15 and a light bulb 16. The lamp 20 is adapted to be energized by an a. c. source 10 which supplies an electric current via an optional switch 11 and a dimmer current control circuit 12. The circuit is completed by a common or neutral connection between source 10 and light bulb 16.

A timer 13 is operable to selectively set an illumination change time interval. The interval is not a transition or instantaneous event,

SUBSTITUTE SHEET

but rather is of major duration, say at least five minutes and in many designs will be up to fifty minutes or more.

The dimmer circuit coacts with the timer 13 to gradually alter the current and change the illumination intensity of bulb 16 from a first level to a second level. For a dimming application the intensity will typically change from full brightness to a night light brightness.

Timer 13 may be a conventional mechanical timer having a user operable dial 14 to selectively set an illumination change interval. The user operates the dial by rotating it to a selected time. As shown in Figure 2, an exemplary dial 14 has a surface with various indicia inscribed thereon. There is an OFF position and an untimed ON position. Timing indicia range from 0 to 50 minutes. By rotating the dial clockwise, the user can select an interval of up to 50 minutes. The maximum rotational travel from 0 to 50 minutes is 180 degrees for this design.

For example, to start the process the user selects a time interval by rotating the dial (not shown) clockwise from the OFF position to a selected time, say 50 minutes. The dial then gradually rotates counterclockwise and 50 minutes later arrives at the zero minute position. The location of this position is chosen (by placement of a stop in coaction with the timing cam on the timer shaft) for minimum brightness, for example, night light brightness. During the 50 minute trip the current is gradually changing so as to gradually dim the light brightness from maximum to minimum.

SUBSTITUTE SHEET

The user imparted rotation is translated to the timer by means of timer input shaft 17. The timer contains a spring (not shown) which is wound to store the rotational energy (as potential energy) and to slowly unwind and release the energy (as kinetic energy) during the selected interval. The released energy is translated from the timer to the dimmer circuit via output shaft 18. The rotational ratio of input shaft 17 to output shaft 18 may vary from one design to another and employ suitable gears where required. For the illustrated design the ratio is one to one.

The timer output shaft 18 is coupled to the rotatable arm of a rheostat contained within the dimmer circuit 12. The dimmer circuit may take the form of any commercially available dimmer circuit with slight modification where necessary to match the rotational travel of the timer shaft to the rotational travel of the rheostat to achieve the desired range of illumination intensity change.

A typical current art dimming circuit is shown in Figure 3 to have a rheostat 21 connected in circuit with various resistors and a capacitor 27 to form an RC timer that controls the switching of switch 28. Switch is typically a triac or other semiconductor switch that is controlled by the RC circuit to open and close at points along the sine wave to control the current delivered to the light bulb in a manner well known in the art. In the exemplary design, the rheostat 21 has a variable resistor element 22 and a rotatable arm 23 which is rotatable by coupling to timer output shaft 18.

SUBSTITUTE SHEET

This is illustrated symbolically in Figure 3 by bidirectional arrow 24. Resistors 25 and 26 are provided to obtain the appropriate time constants with capacitor 27 for the desired brightness range.

In one design embodying the invention, the timer range is 0 to 50 minutes with 180 degrees of timer output shaft travel. The light bulb full brightness is 60 watts and night light brightness is 20 watts. Resistors 22, 25 and 26 are 200, 47 and 820 kilohms, respectively and capacitor is 0.1 microfarad.

Other dimmer or current change circuits can be used including those having double time constants. The mechanical timer can be replaced with an electrical timer with suitable modifications made to the dimmer circuit to match the timer output to the semiconductor phase gating device for current control.

It will be apparent to those skilled in the art that the time dependant illumination control of this invention provides a useful and natural method of illumination which is unavailable to consumers today. It will be relatively inexpensive and provide good value for the expenditure.

While the above description provides many specifics these should not be considered as limitations on the scope of the invention, but instead just an example of a single application. Many other variations are possible. For example, sleep labs would be able to simulate decreased natural illumination to induce sleepiness rather than rely on erratic and humanly controlled methods

SUBSTITUTE SHEET

which will cause unwanted variations in the time and intensity aspects of the experiment or field test.

The time dependent illumination intensity changer can be incorporated in to a number of illumination options and used in a wide variety of manners. The market place will readily use this innovative device in lamps for the elderly, the young, the incapacitated and/or brightening as well as dimming applications. For example, with a 60 watt bulb, the time dependent dimmer will save over ten kilowatts per year. This assumes the device is being used over a time span of one hour, and the alternative is 2the former light being left on for the entire hour.

Significant savings will be realized from an energy consideration by offering these devices to the general public.

Accordingly, the scope of the invention should be determined by a consideration of the appended claims, the illustrated embodiment and of the various design possibilities described herein and their equivalents.

SUBSTfTUTE SHEET