Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1998-07-09
2001-08-28
Negash, Kinfe-Michael (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200
Reexamination Certificate
active
06281999
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to infrared communications systems and, more specifically, to an Improved Optics System for Infrared Signal Transceivers.
2. Description of Related Art
As technology becomes continually more accessible to the “common man,” the ability to use, store, transfer and otherwise manipulate information has become the focus of most businesses as well as for the individual consumer. Access to the information resources is commonly by some sort of network system, including World Wide Web, “Intranets”, local area networks, wide area networks, as well as corporate databases.
While the conventional method for connecting to one of these information networks has been via cable and wire, as the reliance upon connectivity to information has deepened, the desire to gain such access from mobile or portable devices has strengthened. These portable devices, such as Personal Digital Assistants, handheld computers, and even cellular telephones are now being connected to each other and to networks via Infrared Data Communications. In fact, it is virtually impossible to purchase a notebook computer today that does not include an Infrared Data Communications assembly resident within it.
FIG. 1
depicts the typical infrared data communications hardware that is installed in electronic devices; it is a perspective view of a prior infrared transceiver assembly
10
. As discussed above, these assemblies
10
are found in virtually every notebook computer sold today. The components of the assembly
10
are virtually identical across all manufacturers' product lines, with few exceptions. The typical assembly
10
comprises a housing
12
within which the infrared emitter and detector (see
FIG. 2
) are mounted. The “transceiver” is actually data processing circuitry for managing the emitter and detector; it's location is therefore not optically-dependent (and, in fact, it operates better in “IR darkness”). The housing
12
usually is molded from plastic, with a primary lens unit
14
formed in one of the sides of the housing
12
. As can be seen, the conventional primary lens unit
14
comprises two lenses; one each for the emitter and detector (both lenses with similar optical properties, and both requiring precision and reproducibility). Adjacent to the housing
12
, is a protective lens
16
. The protective lens
16
is generally constructed from a colored plastic that is transparent to infrared signals. In most cases, the protective lens
16
is attached to the external case of the electronic device, its purpose being to protect the inner workings of the device, while also permitting infrared signals to pass in and out.
FIG. 2
gives further detail regarding the workings of the prior assembly
10
.
FIG. 2
is a cutaway side view of the prior infrared transceiver assembly
10
of FIG.
1
. As can be seen, the housing
12
is generally attached to the “motherboard”
18
or other printed circuit board within the electronic device. Within the housing
12
is located an emitter/detector pair
20
. It should be understood that it is also common to place more than a single emitter and/or detector inside of one housing
12
(e.g. two emitters and one detector, etc.); an emitter/detector pair
20
is used here simply in the interest of brevity.
The emitter/detector pair
20
transmit and receive infrared signals. The emitter/detector pair
20
is typically mounted to a stand
22
, and thereby positioned in the signal path of the lens
14
in order to send and receive infrared signals therethrough. As discussed earlier, the appliance case
24
has an aperture
25
formed therein, and into which a protective lens
16
is installed. The protective lens
16
simply protects the inner workings of the appliance from contamination.
This prior assembly
10
has several deficiencies. First, the protrusion of the primary lens unit
14
can make the housing
12
difficult to grasp by humans and/or machines assembling the electronic devices. The difficulty in grasping can result in manufacturing defects, production delays, and generally higher costs of production. What is needed is a primary lens unit design that does not present a grasping difficulty to assemblers.
Second, the primary lens unit
14
mandates higher manufacturing and design standards than the average plastic housing for an electronic device to insure that the light-refractive traits of the lens
14
are predictable and repeatable. Because the primary lens unit
14
is integral to the housing
12
, the entire housing
12
becomes subject to the elevated quality standards. It would be much more cost-effective if the design of the integral primary lens unit
14
did not mandate elevated quality standards for the entire housing
12
.
Other defects with the prior assembly
10
are illuminated by FIG.
3
.
FIG. 3
is a cutaway side view of the transceiver assembly
10
of
FIGS. 1 and 2
, depicting the typical transmit dispersion angle &thgr;
T
of the assembly
10
. By current IrDA (Infrared Data Association) standards, the transmit dispersion angle &thgr;
T
must be at least 15 (fifteen) degrees from the focal axis
26
(in two dimensions, of course). The transmit dispersion angle &thgr;
T
is the sum-total of the primary lens refraction angle &thgr;
1
and the protective lens refraction angle &thgr;
2
. All prior assemblies
10
include a protective lens
16
that has no refractive power; the protective lens refraction angle &thgr;
2
is, therefore, typically 0 degrees. Consequently, the conventional primary lens unit refraction angle &thgr;
1
is 15 (fifteen) degrees.
There are several design implications resulting from having the entire transmit dispersion angle &thgr;
T
provided by the primary lens unit
14
. The emitter/detector pair
20
must be located at the focal point
30
of the primary lens unit
14
in order to insure that no signal data is lost. As such, the height
28
(as well as horizontal placement) of the emitter/detector pair
20
is very specifically defined. Moreover, the stand (see
FIG. 2
) must be included in order to raise the emitter/detector pair
20
above the printed circuit board
18
. It would be a better arrangement if the emitter/detector pair
20
could be mounted directly to the printed circuit board
18
. Furthermore, the separation
32
between the primary lens unit
14
and the protective lens
16
is very critical. Unless the primary lens unit
14
is very close to the protective lens
16
, the protective lens
16
must be relatively large or else the mandated angular dispersion will not be met. A large protective lens
16
can be a serious design constraint for the smaller electronic devices, where component real estate is very tight. What would be better is a design that permits the protective lens
16
to be very small, allows the lens separation distance
32
to be flexible, and still meets the IrDA angular dispersion requirements.
SUMMARY OF THE INVENTION
In light of the aforementioned problems associated with the prior devices, it is an object of the present invention to provide an Improved Optics System for Infrared Signal Transceivers. It is a further object that the improved system include a IR transceiver assembly that is easily grasped by assemblers. It is also an object that the primary and secondary lenses associated with the transceiver system be easier to manufacture than current lens designs. It is a still further object that the heretofore critical lens separation between the emitter/detector devices and the primary lens become a flexible dimension, dependent only upon the particular appliance in which the system is installed. It is another object that the stand for emitter/detector devices be eliminated as a result of exchanging a non-imaging transceiver system with the current imaging transceiver system. Finally, it is an object that emitter/detector devices be assembled or otherwise combined into a single emitter/detector device stack.
REFERENCES:
patent: 4279465 (1981-07-01), Vojvodich
patent: 4989934 (1
Hamilton T. Allan
Watson Michael R.
Negash Kinfe-Michael
Steins & Associates
Zilog Inc.
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