Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – In combination with or also constituting light responsive...
Utility Patent
1998-05-29
2001-01-02
Mintel, William (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
In combination with or also constituting light responsive...
C257S082000, C257S084000, C257S085000, C257S098000, C257S099000, C257S100000, C257S432000, C257S433000, C438S025000, C438S026000, C438S027000, C438S028000, C438S029000
Utility Patent
active
06169295
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to infrared (IR) sensors and transmitters, and more particularly to integrated IR transceiver modules.
Infrared transceivers are being used for an increasing number of data communication applications. For example, IR transceiver modules arc used to couple laptop computers and personal information managers (PIMs) to IR ports of printers. Also, an increasing number of portable computer and PIM systems include IR transceiver modules to provide inter-computer and inter-PIM data transfers.
An IR transceiver module typically includes an IR PIN (p-intrinsic-n) diode for a sensor, and an IR light emitting diode (LED) as an emitter. Associated with the sensor is receiver circuitry, and associated with the emitter is transmission circuitry. When the receiver circuitry and transmitter circuitry are integrated together on an integrated circuit (IC), the circuitry is typically referred to as a “transceiver” IC or, simply, a “transceiver.”
While the sensor, emitter, and transceiver of an IR transceiver system can be provided as separate components, it is often desirable to have these components combined into a single package or “module” to save space. Such IR transceiver modules are well known and are commercially available from a number of sources. By combining the various components of the IR transceiver system into a single module, the size or “form factor” of the system can be considerably reduced. In addition, the modules tend to be more durable and often consume less power than equivalent structures formed with the discrete components.
In
FIG. 1
, an IR transceiver module
10
of the prior art includes a unitary, plastic body
12
, defining lenses
14
and
16
and provided with a number of electrical leads or contacts
18
. A typical length “L” for the body
12
is approximately 10 mm, a typical width “W” is 4 mm, and a typical height “H” to the top of the lenses
14
and
16
is approximately 5 mm. It will therefore be appreciated that the IR transceiver module
10
possesses a quite small “form factor”, as compared to providing the same functionality with discrete components.
In
FIG. 2
, a cross-sectional view taken along line
2
—
2
of
FIG. 1
illustrates some of the internal components of the IR transceiver module
10
. The IR transceiver module typically includes a lead frame
20
, an IR sensor
22
, a transceiver IC
24
, and an IR LED
26
. The body
12
encapsulates these components and provides the lens
14
aligned with the sensor
22
and the lens
16
aligned with the LED
26
. Typically, the plastic material of body
12
includes a black dye which blocks visible light, but which allows infrared light to pass through.
The lenses
14
and
16
do not have to be terribly precise, since they are not used for imaging purposes. Rather, lens
14
is used to generally direct IR light
28
towards the active or sensing surface of the sensor
22
. The lens
16
is used to partially focus the IR light
30
produced by the LED
26
in a direction generally perpendicular to the major surfaces of the IR transceiver module
10
. To further aid in the directing of the IR light
30
, the lead frame
20
is bent into a “cup” shape
32
which acts as a reflector for the IR light produced by the LED
26
. This is useful since LEDs tend to generate IR light over a broad emission angle, much of which would be wasted if not reflected by the walls of the cup
32
in the desired direction.
An IR transceiver module similar to the one discussed with reference to
FIGS. 1 and 2
is described in U.S. Pat. No. 5,506,445 of Rosenberg. An alternative but similar design is described in U.S. Pat. No. 5,668,383 of Kriger.
The IR transceiver modules of the prior art are typically designed to conform with the Infrared Data Association (IrDA) standards. For example, IR transceiver modules made by some of the largest manufacturers in the field, including the Hewlett-Packard Company of Palo Alto, Calif., Nippon Electric Company (NEC) of Japan, Sharp Corporation of Japan, and Temic Telefunken Microelectronic, GmbH, of Heilbronn, Germany all produce IR transceiver modules conforming to IrDA standards. These standards include minimum data rates, minimum transmission and reception distances, minimum lumens, etc. for the IR transceiver modules.
While IrDA specifications are useful for standardization purposes, these requirements tend to limit the miniaturization of the IR transceiver modules. For example, the IrDA standards require that the modules be able to transmit light and receive light over a distance of one meter, which requires that an IR sensor
22
be of a certain size, and that the IR LED
26
be of a certain power. In addition, the transceiver
24
must be able to create approximately
150
milliamperes of power to drive the IR LED
26
in order to meet these standards. In addition, the distance and light requirements of the IrDA standards also tends to require the dual lenses
14
and
16
such that the lenses can be optimized for receiving the IR light
28
for the sensor
22
and for transmitting the IR light
30
for the LED
26
. These factors tend to require the separation of the components
22
,
24
, and
26
as illustrated in
FIG. 2
, increasing the form factor of the modules.
It will therefore be appreciated that there exists a need for an IR transceiver module that may not meet IrDA specifications but which has an extremely small form factor. Such an IR transceiver would be useful for applications where the stringent IrDA specifications are not required, but very small size is important.
SUMMARY OF THE INVENTION
In the present invention, an IR transceiver module having a very small form factor is provided with a body having a single lens shared by both the sensor and the emitter. Since the emitter is typically much smaller than the sensor, it can be placed on top of or within a sensing area of the sensor in alignment with the optical axis of the lens. These very small form factor IR transceiver modules can be used in application where small form factors are more important than meeting IrDA standards.
More particularly, an IR transceiver module of the present invention includes a lead frame, a sensor supported near a support surface of the lead frame, an emitter supported near the sensor and within the sensing area of the sensor, and a body encapsulating the sensor and the emitter. The body has an integral lens that is aligned both with the sensing area of the sensor and with the emitter. In several embodiments of the present invention, a transceiver integrated circuit is used to mechanically and electrically couple the sensor to the lead frame. The emitter is then mounted on the sensor within its sensing area.
In certain embodiments of the present invention, a recess is formed in the sensor to receive the emitter. The recess can extend partially through the sensor or can extend completely through the sensor. Preferably, a metal is deposited on the inner wall of the recess to form a “cup” to help direct the IR beam developed by the emitter.
An IR transceiver module as defined by the specification and drawings, and structural equivalence thereof, includes lead frame means, sensor means coupled to the lead frame means and defining an optical axis, emitter means coupled to the sensor means in alignment with the optical axis, and encapsulation means having an integral lens aligned with the optical axis. Preferably, the optical transceiver module further includes transceiver means coupling the sensor means to the lead frame means.
A method for making an IR transceiver module includes the operations of providing a lead frame, coupling a sensor having a sensing area to the lead frame, locating an emitter within the sensing area of the sensor, and encapsulating the sensor and emitter within a plastic body provided with an integral lens aligned with both the sensor and emitter. In one embodiment of the present invention the method further includes the operation of forming a recess within the sensor that is receptive to the emitter, and
Hickman Coleman & Hughes LLP
Maxim Integrated Products Inc.
Mintel William
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