Patent Application
20200393111
This disclosure relates to an illumination system in which the size of light beams that impinge on a target can be altered without changing beam brightness or intensity.
In several environments of use, such as but not limited to doctor's examining room or an operating theater in a hospital, it would be desirable for an operator to adjust beam size or diameter while maintaining intensity across the beam size adjustment range.
Several alternative embodiments include a system for generating a beam of light that impinges on a target, wherein beam intensity remains substantially constant regardless of beam spot size. In some cases, the system comprises a light source, one or more optical control devices such as dynamic optics or lenses, an optical position feedback encoder and a brightness control circuit.
One way to use such a system involves a method for generating a beam of light that impinges on a target, so that beam intensity remains substantially constant regardless of beam spot size. The method includes these steps:
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The Figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
It will be appreciated that in many conventional environments, a light source does not change its emitted brightness as beam diameter changes following lens re-positioning. This generally causes the spot's intensity at a target location to increase as beam diameter becomes smaller. One consequence may be unwanted heat generation, particularly over time.
Consider a beam of light that impinges on a target. One aim of this disclosure is to provide a system and method for changing the size of a spot of light projected at a target (e.g., by beam angle adjustment or re-positioning a lens) while maintaining beam intensity throughout the entire range of spot size adjustment.
One way to practice the disclosed system and method is depicted in the flowchart of
In several embodiments (e.g.
One way to use the disclosed illumination system (see, e.g.,
In another embodiment (see,
In practice, a user first manually adjusts the location of a dynamic optic or lens. This step may be accomplished by for example, mounting the dynamic optic on a slide feature along which the dynamic optic may selectively be positioned. In
An optical position feedback encoder sends a position signal to the brightness controller circuit. The position signal reports the location of the lens. In one embodiment, the brightness control circuit includes an encoder translator circuit which communicates with a microprocessor on which one or more equations are executed. The microprocessor also receives user inputs (such as desired beam size) that characterize variables associated with the particular application. Outputs from the microprocessor include power signals that are delivered to a power control circuit. In turn, that circuit communicates with the light source so that electrical power delivered to the light source changes in response to the position of the dynamic optic in order to generate a light beam that has a substantially constant intensity, regardless of the size of the beam that is directed at the target location.
Thus, the power control circuit adjusts the electrical power delivered to the light source. This causes the target location to receive a constant intensity of the incident light beam, regardless of beam diameter.
As mentioned, the brightness controller includes a microprocessor that uses one or more equations (to be discussed later) to calculate the required electrical power level, preferably in real time as lens movement occurs for the light source to maintain a constant intensity of the newly sized beam.
In some cases (e.g.,
A beam size signal (Bs) is communicated via user input variables (e.g. desired beam size) to the brightness controller circuit and in turn to the microprocessor. One output is an instruction that is relayed to the power control circuit. In turn, that circuit communicates a signal (PW) which signifies a desired power level that is delivered to the light source.
That signal (PW) informs the light source so that a predetermined power output is delivered by a power pack to the light source. That power level causes a beam to be generated that passes through the dynamic optic to the target. There, beam intensity is substantially constant, regardless of beam size.
One way to practice this embodiment of the disclosed illumination system calls for the operator to provide electromechanical lens adjustment inputs via buttons, for example on a control pad. This step positions the optics through the dynamic optical positioner (
Consider the flowchart of
A desired beam size signal (BS) is provided to the brightness controller (e.g. by user input). Then, the dynamic optic actuator moves the lens into the required position. Next, an optical position feedback encoder informs the brightness controller about the position of the dynamic optic as movement occurs, or after movement ends. Subsequently, the microprocessor of the brightness controller uses an algorithm to calculate the required electrical power. This calculation is made in real time so that the light source maintains a substantially constant intensity over the area of a newly sized beam. In the brightness controller, the power control circuit adjusts the electrical power that is delivered to the light source. This causes the beam at the target location to maintain a constant light intensity over a range of beam sizes.
In one set of experiments, the following exemplary observations were made of lens position, beam size, and electrical power required to produce beams of a substantially constant intensity:
Thus, several embodiments of the disclosed illumination system uniquely allow brightness to be maintained by:
(1) observing the size of the beam spot;
(2) providing feedback of beam size to a control circuit;
(3) computing an amount of light source power intensity adjustment required to maintain actual beam intensity as beam size changes; and optionally
(4) processing an operator input to change beam size.
Consider further the exemplary embodiments of
That signal (Lp) is transmitted wirelessly or by cable to the brightness control circuit (
The distance between the dynamic lens and the light source influences the size of the spot (Bs). The controller then generates a voltage or current (collectively, “power”) signal PW and transmits it to the light source. In one embodiment, the light source includes one or more LED's, halogen bulbs, or the like. That signal adjusts the output of the light source to maintain the desired uniform brightness regardless of spot size (BS).
It will be appreciated that the controller includes an analog or digital encoder. Representative encoders are described for example at encoder.com/blog/company-news/what-is-an-encoder, which is incorporated by reference. The encoder communicates with a microprocessor (see, e.g., www.microchip.com, which is incorporated by reference) that executes software which processes an algorithm or one or more equations. Variables considered by the algorithm include specifications of the optics, LEDs, and LED driver(s) used. Typical lens types include those available from LEDil (www.ledil.com) and Khatod (www.khatod.com). The contents of those websites are incorporated by reference.
A representative equation for computing the power of light source to produce a given beam size is:
where
P=electrical power
r=radius of desired beam size
m=radius of maximum beam size
w=power at maximum beam diameter
o=optical efficiency variable
s=source efficiency variable
t=temperature coefficient variable.
The output signal (PW) from the circuit is delivered to the light source. The signal is a function of amperage, voltage or power. As a consequence, the light source is adjusted to shine brightly, dimly or at an intensity therebetween in order to produce a desired intensity of beam at the target, regardless of beam size.
Optionally a static lens or optic may be provided that serves as a collimator. A reflector may optionally be provided as an adjunct to any of the lenses disclosed.
In use, the lens, controller circuit and light source are often packaged together. Optionally, the controller circuit may be positioned remotely from the light source.
If desired one or more cooling subsystems (e.g., an aluminum heat sink or a liquid-cooled feature) may be deployed in relation to the light source.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
