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BACKGROUND OF THE INVENTION
The present invention relates generally to an optical mask adapted to shine
a sustained bright light into the wearer's eyes at selected times to
modify circadian rhythms.
It has long been known that biological processes in most, if not all
organisms vary rhythmically over time, and that the timing of these
rhythms can be affected by exposure to light. Recent research suggests
that the light must be very bright if it is to effectively modify
biological rhythms in humans. Using carefully timed exposure to bright
light, scientists have been able to change people's cycles of sleep and
wakefulness, body temperature and hormonal secretion. Additionally, bright
lights have been found useful in treating certain psychiatric disorders
such as seasonal affective disorder and depression. It has also been
suggested that light treatment may be useful to fight various sleep/wake
problems such as jet lag and tiredness associated with shift work, and to
improve nighttime vigilance and performance.
Bright lighting systems for modifying biological rhythms have traditionally
consisted of large, bulky banks of fluorescent tubes or specialized bulbs.
Such systems have several inherent drawbacks, including high energy
consumption, high heat production and limited transportability. These
restrict their usefulness outside of the laboratory environment,
especially for mobile applications such as the treatment of jet lag.
Furthermore, some research has suggested that the critical time for bright
light exposure for many therapeutic purposes is either late at night or
early in the morning, when subjects are ordinarily asleep. Another
advantage of bright light treatment during sleep time is that it does not
take time away from preferred wakeful activities. With traditional
lighting systems, subjects must be awake to receive treatment, for if they
fall asleep they may shield their eyes or look away from the light source
and thus receive insufficient exposure.
Therefore there is a need for a bright light source that is lightweight and
transportable; develops sufficient light intensity to produce the desired
biological effects; and reliably directs light into the user's eyes
regardless of body position during sleep. Additionally, there is a need
for a bright light source which may be turned on and off at preselected
times during the day or night and is capable of turning on gradually so as
not to disturb a wearer.
SUMMARY OF THE INVENTION
Accordingly, it is the primary objective of the present invention to
provide a light weight and portable bright light source capable of
generating a light intensity bright enough to modify human biological
rhythms.
Another objective of the present invention is to provide a bright light
source that includes a timer for turning on and off the light source at
preselected times.
Another objective of the present invention is to provide a light source
capable of varying the intensity of the light emitted.
Another objective of the present invention is to provide a light source
that shines reliably into the eyes regardless of body position and without
conscious effort on the part of the user.
Another object of the invention is to provide high intensity light to a
subject's eyes without requiring high energy consumption.
To achieve the foregoing and other objects, and in accordance with the
purpose of the present invention, a bright light mask system is provided
for shining a high intensity light into a subject's eyes to modify
circadian rhythms. The bright light mask includes a mask to be worn by the
subject and adapted for covering a subject's eyes regardless of body
position. The mask includes at least one light admitting aperture that is
substantially transparent to light energy. A light means that is coupled
to the light admitting aperture generates and delivers light through the
light admitting aperture onto the subject's eyes. The light means includes
a light source that light having a wavelength in the range of 500 to 600
nanometers, and delivers light having an intensity of at least 2000 LUX to
the subject's eyes. A control means regulates the delivery of light to the
subject's eyes.
Preferably the control means includes a timer means for selectively turning
on and off the light source for at least 15 minute "on" cycles.
Additionally, a dimming means controls the intensity of light delivered to
the subject's eyes. Specifically, the dimming means is adapted to
gradually increase the intensity of the bright light when the device is
first turned on.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel are
set forth with particularly in the appended claims. The invention,
together with further objects and advantages thereof, may best be
understood by reference to the following description of the presently
preferred embodiment, taken in conjunction with the accompanying drawings
in which:
FIG. 1 is a front view of a bright light mask system 1 in accordance with
the present invention.
FIG. 2 is a schematic view of an embodiment of the light means appropriate
for use in the bright light mask system shown in FIG. 1.
FIG. 3 is a side view detailing the fiber optic to mask connection of the
bright light mask system shown in FIG. 1.
FIG. 4 is an alternative embodiment of the bright light mask system of the
present invention.
FIG. 5 is a circuit diagram of a controller suitable for use with the
present invention.
FIG. 6 is a suitable layout for the circuit diagram shown in FIG. 5.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
As illustrated in the drawings, bright light mask system 1 of the present
invention includes a standard sleep mask 3 having at least one light
admitting aperture 5 therein, and a light means 7. The mask is adapted to
cover the subject's eyes and its light admitting aperture 5 is transparent
to light energy. The light means 7 generates light and directs the light
through the light admitting aperture 5 in mask 3 and onto the subject's
eyes. A controller 9 regulates the timing and intensity of the light
source.
Referring initially to FIGS. 1-3, a presently preferred embodiment of the
bright light mask system 1 will be described. The mask 3 is an ordinary
sleeping mask worn to block out light at night when the user is asleep. A
pair of openings 5 (which form the light emitting aperture) are cut into
the mask directly over each eye. In order to modify circadian rhythms, it
is necessary to deliver light that includes at least 2000 LUX at
wavelengths in the range of 500-600 nm. The bright light generally must
remain on for at least 15 minutes. In this embodiment, the light means 7
includes a single light source 11. A wide variety of conventional light
sources may be used so long as they produce the required light. By way of
example, as shown in FIG. 2, a standard incandescent flashlight bulb 11
complete with a curved reflector 12 for directing the light forward may be
used as the light source. Filters 15 may optionally be used to control the
type of light that enters the eyes. For example, it may be desirable to
block either infra red or ultra violet rays depending upon the light
source used. Additionally, in some applications it may be desirable to
color filter the light. Heat generated by the light source is the major
concern when incandescent bulbs are used. Therefore a heat reflective
filter made of a material such as mylar will minimize heat delivery to the
eyes while exposing them to bright light.
Referring also to FIG. 3, fiber optic cables 21 direct the filtered light
from the light source 11 to the mask openings 5. Referring now to the
junction between the mask and the fiber optic cables, spreader lens 27 is
coupled to the distal end of each of the fiber optic cables 21 in order to
disperse the light inside mask 3. The attachment between lens 27 and cable
21 is facilitated by a sleeve 28. A rigid holder 22 having a reflective
concave inner surface 24 is disposed within the mask openings 5 and
secured to the mask 3 by any conventional fastening means. Controller 9
functions both as a timer that is capable of turning the light source 11
on at various selectable time intervals and controlling the intensity of
the light source. Electrical wires 18 join the light source to the
controller. A more detailed description of the light source is provided
below.
An alternative embodiment of the light means 7 is illustrated in FIG. 4. In
that embodiment, a pair of light sources in the form of miniature
incandescent light bulbs 11 are placed directly in front of the openings 5
in mask 3. Filters 15 are particularly important in this embodiment to
reduce the amount of heat reaching the eyes, since excess heating of the
eyes could be damaging and the buffer inherently provided by fiber optic
cables 21 is nonexistent. Alternatively, banks of high brightness green
light emitting diodes could be used in place of the incandescent light
bulb. The LED banks have the advantage of having lower power consumption
and less heat dissipation. However, LED's of sufficient brightness are not
readily available at economical prices.
In both of the embodiments described, a controller 9 controls the intensity
of the light generated and the timing during which the light is on. It is
frequently desirable to turn on the lights at preselected spaced intervals
and particularly while the subject is asleep. Therefore, the controller 9
includes a timer 31 which may be set to turn on and off at any number of
spaced time intervals. An intensity controller 33 controls the intensity
of the light generated by light source 11. To avoid waking a sleeping
subject, it is desirable to slowly increase the intensity of the light
from OFF to full ON since sudden intense light changes will often awaken a
sleeping subject. By way of example, ramping times in the vicinity of 16
minutes have been found to be appropriate.
The timer 31 includes a delay select switch 32 that allows the user to
select a desired delay after which the light will turn on. Once the light
has been turned on, intensity controller 33 incrementally increases the
intensity of the light until the light is fully on. In essence, the
controller functions as a variable voltage/current source which slowly
increases the intensity of the light delivered to the subject's eyes.
Duration select switch 34 controls the amount of time the light is on. By
way of example, in the embodiment of the controller suitable for use with
the present invention described below, the delay select switch 32 has
hourly incremental delays of 0 to 15 hours while the duration select
switch has incremental delays on the half hour between 0 and 7.5 hours.
Also by way of example, the light gradually intensified from off to full
power over a sixteen minute time period.
It should be appreciated that the present invention differs fundamentally
from the prior art in that the intensity of the light source may be
dramatically lower than the prior art while still delivering light bright
enough to affect biological rhythms. This is due to the proximity of the
light source to the subject's eyes, since as a light source is moved
closer to an object being illuminated, the intensity of the light reaching
the object is dramatically increased.
The bright light mask described will shine light of high enough intensity
(at least 2,000 LUX) for a long enough duration (15 minutes to many hours)
to produce a specific biological stimulus capable of rapidly and
significantly shifting circadian rhythms and reducing the level of the
hormone melatonin. Therefore, the mask applies energy to an organism to
directly produce a physiological change. The bright light mask will not
change biological rhythms unless the light is presented at the proper time
of day. The mask described includes circuitry to control the on/off
operation of the light.
A particular problem encountered by bright light sources is that the
intensity of the light would be disturbing and possibly even damaging to
the eyes if the light is turned on all at once. Therefore, the bright
light mask described, is designed to turn on gradually.
Delivering bright light through a mask presents the special problem of
delivering excessive heat to the eyes. In the initial embodiment
described, this problem is overcome using fiberoptics to deliver the
light, thereby removing the bulbs from the proximity of the wearer's eyes.
Additionally, heat-reflective filters made of material such as Mylar
provide another way to minimize heat delivery to the eyes while still
exposing them to the bright light.
One embodiment of the controller 9 suitable for use with the bright light
mask is shown in FIGS. 5 and 6. As shown therein, the circuit is designed
to run from an on-board 5.0 volt regulator, which requires an external
source of power of 7 volts or more. The light device driven by this device
may require any voltage. The external power supply may be as high as 30
volts, though something closer to 12 volts is recommended.
The light device and supply voltage should be arranged so that the supply
voltage is as close as possible to 2-3 volts above the voltage required by
the light device. This is to avoid wasting power--which must be dissipated
by the power transistor (Q2). By way of example, an SK3199 medium power
transistor, or equivalent, rated as 10 watts and 2 amperes, should be
sufficient for most configurations. A higher rated power transistor might
be required if the voltage source greatly exceeds the requirements of the
lamps or devices.
The 5 watt potentiometer (P1) allows adjustment of the circuit for
different light devices. The circuit is capable of driving currents from
1/10 to 1 amp, roughly. The actual current driven may be measured by
connecting a voltmeter between two "tie-points": from TP1a to TP1b. These
tie points are indicated on the circuit layout shown in FIG. 6.
There is an on-board lamp which is switched into the circuit when the light
device is not connected into the 2.5 mm dc jack. This allows easy
demonstration of the circuit functioning independent of external light
devices.
A two-choice jumper connection on the circuit board may be used to allow
normal operation, or "test-operation" at a much faster rate, to allow
circuit demonstration and checkout. (The jumper connections are shown on
the circuit layout.) The timing parameters for normal and test operation
are listed below.
______________________________________
Function Normal Oper. Test Oper.
______________________________________
Delay (0-15 steps)
60 min 28.13 sec
Duration (0-15) 30 min 14 sec
Turn-on ramp step
56.25 sec 0.44 sec
Turn-on ramp total
15 min 7.0 sec
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(As used herein and on the diagrams, signal levels are indicated in
underlined boldface. Signals, such as EN, are considered to be active when
high, unless the complement, such as -LD, is indicated.)
The timing signals originate from a 32.768 kilohertz crystal oscillator
(Z1), which is divided (by Z2) by 4096 [or by 4096/128=32, in test mode],
resulting in an 8 Hz signal [1024 Hz, test mode] output.
In Z3 and Z4 each ripple carry output (-RC, low) is connected to its own
load input (-LD, load when low) so that each overflow of the counter will
cause an automatic reload of the programmed inputs (A through D). The
preset inputs are set at a value of 0, so that 15 counts are required for
overflow. Thus, Z3 and Z4 act as modulo 15 counters.
(The two divisions by 15 are required to convert seconds into hours. The
crystal oscillator is designed to produce exactly one second when divided
by 2, 15 times. The subsequent divisions by 60, to convert to minutes and
hours, require two divisions by 2 and a division by 15, each. The
divisions are not actually done in that order--to save components.
Actually, 12 divisions by 2 are done in Z2, followed by the two divisions
by 15 in Z3 and Z4, followed by the remaining divisions by 2 for each
timing signal in Z5.)
The signal leaving Z4 has a period of -28.125 seconds [0.22 s, test]. It is
fed into Z5 to generate the 1/2-hour signal required for duration and the
1-hour signal required for delay, and the 56.25 seconds [0.44 s, test] fed
into Z8 to generate the "turn-on" ramp.
When the power is first turned on, an R-C circuit provides a one second
reset signal, high (RS) from Z9a, and low (-RS) from Z9b. These signals
are used to reset counters Z5 (time division) and Z5 (delay). The effect
of reset is passed on to counters Z7 and Z8 by Z6.
The reset signal (-RS) is connected to the load input (-LD) of Z6 so that
when power is first turned on the preselected value of delay (Sw1,
complemented value determined by D1a through D1d) is loaded into the
counter; counting commences at the end of the 1 second reset. The output
of Z6 (M/M) is connected to the load (-LD) inputs of Z7 and Z8. While Z6
is counting, its M/M output (which is low until overflow) keeps Z7 and Z8
at their preset load values, not allowing them to count. When Z6's delay
count of is exhausted, its M/M output goes high, and both Z7 and Z8 are
allowed to start counting.
Z8 counts at a fairly fast rate (56 sec steps), and when it overflows, its
output (RC) (inverted by Z9d and connected to its own enable input (ENP))
causes inhibition of its own counting--it is "stuck" in the "on" state.
(It is important that the low signal on ENP disables the clocking
(counting), but not the output--since counting is disabled, the output
will not change, and Z8 stays at its maximum count). The four (binary)
outputs of Z8 are connected to resistors which are "weighted" by powers of
two, so that the combined outputs produce an analog voltage which is
proportional to the binary number reflected in the counter. The 2.7K
resistor (to ground was selected so that the maximum voltage 9Z8 at
maximum count would be 1 volt. The output of this digital-to-analog
converter is connected to the lamp drive circuitry described below.
At the same time that Z8 starts its "turn-on" count, the much slower
duration counter Z7 also begins its count (of half hour intervals). When
its count is completed, its output (M/M, inverted by Z9c and connected to
the clear input, -CL, of Z8) clears Z8 (which was "stuck" in the on-state
at the end of its ramp). Since the M/M output of Z7 is connected to its
own enable input (-EN), it remains in its on-state--keeping Z8 cleared
(lamp off) until power is turned off and then on again.
Although only a few embodiments of the present invention have been
described herein, it should be apparent to those skilled in the art that
the present invention may be embodied in many other specific forms without
departing from the spirit or scope of the present invention. Particularly
a wide variety of light sources, mask arrangements, filters and
controllers could be fabricated to accomplish the goals of the present
invention. Additionally, it should be appreciated that the bright light
mask may be used to modify biological rhythms of a wide variety of
subjects, in addition to humans. Thus, it is contemplated that suitable
subjects would include, for example, laboratory monkeys, race horses, or
animals being transported long distances. Therefore, the present examples
and embodiments are to be considered as illustrative and not restrictive,
and the invention is not to be limited to the details given herein, but
may be modified within the scope of the appended claims.
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