Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
2000-02-18
2002-01-29
Kim, Robert H. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S23700G, C362S298000
Reexamination Certificate
active
06342695
ABSTRACT:
FIELD OF THE INVENTION
The present inventions relate to transducer systems for emitting or detecting radiant energy, for example optical energy. The inventive concepts involve transducer systems utilizing principles of constructive occlusion as well as specific techniques for tailoring the performance characteristics of such systems.
BACKGROUND
Radiant energy transducers find a wide range of applications in modem technology. Electrically driven transducers, for example, emit radiation to illuminate a desired area or footprint. The transducer system may illuminate the area for a number of reasons. For example, if the emitting transducer emits visible light, the illumination may facilitate use of the area by human personnel. If the illumination of the area provides infrared radiant energy, the illumination may facilitate some associated detection operation or human monitoring of the area through special night vision equipment.
Other radiant energy transducers detect radiant energy from within a desired field of view and provide signals for further electrical processing. For example, a light detecting transducer may provide signals that a processor can analyze to determine the direction and/or intensity of incoming light. The processed information may represent a position of a reflective object or light source within the field of view. These are just a few examples of the applications of radiant energy transducer systems.
Different applications of radiant energy transducers require different transducer performance characteristics. For example, an illumination application might require that the transducer uniformly illuminate a flat surface of a specified area (the footprint) at a known distance and angle from the transducer with a specified radiation intensity. Typically, the specification for such an illuminating transducer would not specify the amount of radiation transmitted to areas outside the specified footprint. Simple radiation sources, such as light bulbs or lights with reflectors and/or lenses typically distribute a substantial amount of radiation outside the desired footprint. This reduces efficiency. Stated another way, to achieve the desired illumination intensity within the footprint, the power applied to the transducer must be relatively large in order to allow for the energy lost to areas outside the desired footprint. Also, such a system often over radiates a portion of the desired footprint.
Similar problems arise in radiant energy detecting transducers. To insure adequate sensitivity to energy from within the field of view, the transducer typically will receive additional radiant energy from outside the desired field of view. Also, it often is difficult to maintain uniform sensitivity over the entire field of view.
Prior attempts to address these problems have involved complex arrangements of lenses and reflectors. Such arrangements make transducer manufacture expensive. Such arrangements also are subject to problems of misalignment and raise concerns about the durability and ruggedness, in applications outside of laboratory conditions.
A need therefore exists for radiant energy transducer systems, e.g. emitters and detectors, having high efficiency and desired operational characteristics for specific applications. The transducer systems should be relatively easy to manufacture and therefore relatively inexpensive. Also, there is a need for transducers of this type that are relatively rugged and durable, when used in real applications.
CONSTRUCTIVE OCCLUSION
Applicants have developed a number of radiant energy transducer systems, which reduce some of the above noted problems, based on a theory of beneficial masking referred to as ‘Constructive Occlusion’. Constructive Occlusion type transducer systems utilize an electrical/optical transducer optically coupled to an active area of the system. The systems utilize diffusely reflective surfaces, such that the active area exhibits a substantially Lambertian characteristic. For example, the active area may comprise a diffusely reflective cavity formed in a base. A mask occludes a portion of the active area of the system, in the example, the aperture of the cavity, in such a manner as to achieve a desired response characteristic for the system.
For example, in a series of prior related cases, applicants disclosed cavity and mask based transducer systems that provide uniform response characteristics (e.g. emission energy for light distributors or sensitivity for detectors) over a wide range of angles relative to the transducer system. The prior Constructive Occlusion cases include U.S. Pat. Nos. 5,705,804, 5,773,819, 5,733,028 and 5,914,487, the disclosures of which are incorporated entirely herein by reference.
Applicants' prior Constructive Occlusion type transducer systems have allowed considerable tailoring of the optical/electrical performance characteristics of radiant energy transducing systems. However, some desired applications require still further enhancements to achieve the desired system characteristics, and a need still exists to further increase the efficiency of the transducer systems. For example, a need still exists for a transducer system of even higher efficiency exhibiting uniform performance over a designated planar surface.
SUMMARY OF THE INVENTION
The objective of the invention is to produce a radiant energy transducer system having a tailored intensity characteristic over a desired footprint or field of view.
Another objective is to maintain a relatively high efficiency of the transducer characteristic over the footprint or field of view.
One more specific objective is to provide a transducer having a planar uniformity of response or illumination over a desired footprint.
The inventive concepts involve a series of ‘tailoring’ techniques, which enable the system designer to adapt a transducer system to a specific illumination or detection application requiring a particular performance. One of these techniques utilizes the principles of constructive occlusion, with selection of the optical parameters of the constructive occlusion system, to satisfy the performance demands of the particular application. Constructive occlusion utilizes a mask sized and positioned to occlude a substantial portion of an active optical area, such as an aperture of a diffusely reflective cavity, in such a manner as to provide the desired performance characteristic.
Constructive occlusion of this type may be used alone or in combination with several other techniques. One additional mechanism used to further tailor performance involves a non-diffuse reflective shoulder (specular or retro-reflective) around a peripheral section of the mask and cavity type transducer system. Another technique involves using a retro-reflector along a portion of the periphery of the system, to limit the angular field of view and to redirect certain light back into the system for further optical processing.
Another technique, used with a mask and cavity type constructive occlusion system, involves use of one or more reflective walls along one side of the system. The reflective walls limit the field of view to angles on the opposite side of the axis or plane of the walls.
These techniques enable a system designer to adapt the transducer system to a wide range of applications. A lighting system, for example, may uniformly illuminate a distant planar surface, such as a desktop or a section of a floor or ceiling. The resulting transducer systems are relatively simple in structure, making them easy to manufacture and rugged.
The present invention uses materials having a variety of different types of types of reflectivity. Recall for example that a material providing a diffuse reflectivity reflects light, impacting at an incident angle to the surface, over a range of angles of reflection, i.e. in many different directions. A material providing a specular reflectivity reflects light impacting at an incident angle to the surface in a new direction, but the angle of reflection relative to the surface equals the angle of incidence. A material or
Bagwell Richard S.
Rains, Jr. Jack C.
Ramer David P.
Advanced Optical Technologies, LLC
Kim Robert H.
McDermott & Will & Emery
Thomas Courtney
LandOfFree
Enhancements in radiant energy transducer systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Enhancements in radiant energy transducer systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Enhancements in radiant energy transducer systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2824711