BI-CURVATURE LENS FOR LIGHT EMITTING DIODES AND PHOTO DETECTORS
A bi-curvature lens for diodes in an infrared wireless communication transceiver is disclosed. Devices having such a bi-curvature lens, such as a light emitting device, a light detecting device, and a transceiver are also disclosed. A method for designing such a lens, and a method for fabricating a device having such a lens are also disclosed. The bi-curvature lens disclosed has a bottom hemispherical portion and a top aspherical portion. Light emitting diodes and photo detectors used in conjunction with bi-curvature lenses display symmetrical radiation intensity profiles, in accordance with Infrared Data Association standards and protocols.
This is a divisional continuation application of copending application Ser. No. 11/074,883 of Kuldeep Kumar Saxena et al., filed Mar. 7, 2005, for BI-CURVATURE LENS FOR LIGHT EMITTING DIODES AND PHOTO DETECTORS, the entire disclosure of which is hereby incorporated by reference herein.
FIELD OF THE INVENTIONEmbodiments of the present invention pertain generally to wireless communication devices. More specifically, embodiments of the present invention pertain to lenses used with light emitting diodes (LED) or LEDs chip/die and photo detectors (PD) or PDs chip/die in wireless communication devices.
BACKGROUND OF THE INVENTIONLight emitting diodes (LEDs) and photo detectors are widely used with or without lenses to facilitate wireless infrared communication in devices such as laptop computers, personal digital assistants, printers, mobile phones, modems, digital pagers, electronic cameras, and hand-held computers. The growing popularity of wireless communication has placed a tremendous demand for small form factor for components such as transceivers within wireless communication devices.
In a typical wireless communication device, an infrared transmitter (e.g. an LED chip/die with lens) is arranged adjacent to an infrared receiver (e.g. a photo detector chip/die) in an arrangement called a transceiver. An embedded LED chip/die with lens is called an emitter. An embedded PD die/chip with lens is called a transmitter. The transmitter and the receiver are connected with an integrated circuit for signal processing. On the surface of the transceiver, there are two lenses. A light emitting diode chip/die is located in or near the center of one of the lenses, and a photo detector chip/die is located in or near the center of the other lens. Conventionally, spherical lenses 110 described by a radius r (115), as depicted in
One method of evaluating LED lenses is the generation of a radiant intensity profile. The radiant intensity profile indicates flux of radiation per steradian of the surface of a lens. The term flux, in this context, refers to the energy per steradian of the emission of the LED. A steradian 210 is a three dimensional unit of spherical geometry, depicted in
A radiant intensity profile for a spherical lens is presented in
One approach to meeting the current demand for smaller components within wireless devices is to manufacture smaller spherical lenses for use with LEDs and photo detectors in infrared transceivers. However, as the diameter is decreased for spherical lenses used with LEDs, the brightness of the LEDs decreases, therefore signal output is compromised. As the diameter is decreased on spherical lenses used with photo detectors, less light is received at the photo detector, therefore signal processing is compromised.
SUMMARY OF THE INVENTIONEmbodiments of the present invention, a light emitting device having a light emitting diode chip/die and a bi-curvature dome lens are disclosed. The bi-curvature dome lens according to embodiments of the present invention has a hemispherical bottom portion defined by a first radius and an aspherical upper portion defined by a second radius and a conic constant.
BRIEF DESCRIPTION OF THE DRAWINGSThe accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention:
Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with various embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and the scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, structures and devices have not been described in detail so as to avoid unnecessarily obscuring aspects of the present invention.
One embodiment of the present invention is a bi-curvature dome shaped lens 400, depicted in
Referring now to
The diameter of a lens in accordance with the present invention can be smaller than the diameter of a conventional spherical lens. Thus, a transceiver having bi-curvature lenses can be smaller and more compact than a transceiver having spherical lenses. A wireless communication device having transceivers with bi-curvature lenses can be smaller and more compact than a wireless communication device having transceivers with conventional spherical lenses.
One embodiment of the present invention is the design method employed to obtain a bi-curvature dome capable of emitting light of symmetrical radiant intensity, in both the horizontal and the vertical directions. One design method is recited in flowchart 900 of
In one embodiment, a wireless communication transceiver is fabricated by a transfer mold method as recited in flowchart 1000 of
It can be appreciated that the bi-curvature dome lens of the present invention can be formed from any material rendering efficient light transmission. A bi-curvature dome lens in accordance with embodiments of the present invention is not limited to infrared wireless communication applications. Embodiments of the present invention permit optics designers to achieve desired radiant intensity profiles using very small lenses, e.g. lenses having very small diameters. The cost of fabrication of bi-curvature lenses is comparable to the cost of fabrication of conventional spherical lenses.
The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments of were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.
Claims
1. A light detecting device comprising:
- a photo detector; and
- a bi-curvature dome lens comprising: a hemispherical portion comprising a first radius; and an aspherical portion comprising a second radius and a conic constant not equal to zero.
2. The light detecting device of claim 1 wherein said photo detector is a photo detector chip, wherein said photo detector chip is embedded in said bi-curvature dome lens.
3. The light detecting device of claim 1 wherein said photo detector is a photo detector die, wherein said photo detector chip is embedded in said bi-curvature dome lens.
4. A method of detecting light comprising:
- transmitting light through a bi-curvature lens, said lens comprising a first hemispherical portion and a second aspherical portion; and
- receiving light at a photo detector.
Type: Application
Filed: Aug 7, 2007
Publication Date: Feb 7, 2008
Inventors: Kuldeep Saxena (Singapore), Wee Tan (Singapore), Peng Ng (Singapore), Sin Lim (Singapore)
Application Number: 11/835,065
International Classification: G02B 3/10 (20060101);