Light source with gradually changing intensity

• US 5,008,865 A
• Filed: 05/17/1990
• Issued: 04/16/1991
• Est. Priority Date: 07/20/1988
• Status: Expired due to Term

• Current Assignee: Blaine P. Shaffer
• Original Assignee: Blaine P. Shaffer
• Inventors: Shaffer, Blaine P., Haab, William G.
• Primary Examiner(s): Miska, Vit W.
• Application Number:
  US07/525,877
• Time in Patent Office: 334 Days
• Field of Search: 368/10, 368/12, 368/72-74, 368/79, 368/250, 368/256, 315/360
• US Class Current: 368/10
• CPC Class Codes: G04G 11/00 Producing optical signals at preselected times
• CPC Class Codes: H05B 39/083 by the variation-rate of light intensity
• CPC Class Codes: H05B 47/16 by timing means
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

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 increased. 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. The circuit may be either analog or digital. In each embodiment, an optocoupler is controlled to lower the firing angle of a triac to gradually increase the intensity of the light. The circuit 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.

Claims

1. An apparatus for varying the brightness of a light in a smooth and gradual manner, comprising:

an A.C. power supply source means for providing power to said light at a frequency and power generally available on a power distribution system, said A.C. power supply having zero crossings;

a zero crossing sensor means for sensing each zero crossing of said A.C. power supply and outputting a zero crossing signal at each of said zero crossings;

an oscillator circuit coupled to the output of said zero crossing sensor and receiving said zero crossing signals, said oscillator circuit outputting an oscillating frequency signal having a plurality of zero crossing points in between each zero of said A.C. power supply and at least one of said oscillator zero crossings occurring simultaneously with said A.C. power supply zero crossings;

a micro computer circuit having an internal timing clock controlled by said oscillator'"'"'s zero crossings to ensure that said timing clock generates pulses whose occurrence is exactly positioned relative to said zero cross of said A.C. signal, said micro computer circuit including a trigger, a pulse output line, and an input signal line, said trigger pulse output line going high at a selected time after said A.C. signal zero crossing as measured by said internal timing clock, 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 A.C. zero crossing than said first time occurs after said A.C. zero crossing, said selected time gradually varying from said first time to said second time after said input signal goes high;

a gate circuit coupled to said trigger pulse output line, said gate circuit going high when said trigger pulse line goes high; and

a triac circuit having its gate coupled to said gate circuit for causing said triac circuit to turn on and provide power to said light from said trigger pulse output going high until said A.C. 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.