Lens unit and light pipe assembly

A light transmission device, comprising in combination a longitudinally axially extending light pipe; and a lens unit having a light transmitting end wall and structure extending away from the end wall generally axially and sidewardly of the light pipe, the light pipe and the lens unit retained in assembled relation, whereby light is transmitted from the light pipe to the end wall.

BACKGROUND OF THE INVENTION 
Such applications and patents are incorporated herein, by reference. 
This invention relates generally to optical coupling of light sources and 
fiber optics cables, or light pipes; and more particularly concerns 
optical coupling of lens units and light fibers in such a way as to 
position the light pipe to receive light transmission from a light source 
spaced endwise from the light source, such as an LED. 
There is need for improved apparatus and method to overcome difficulties in 
optical coupling as between light sources, light pipes and lenses. 
SUMMARY OF THE INVENTION 
It is a major object of the invention to provide improvements in such 
optical coupling as will meet the referenced need. Basically a light 
transmission device in accordance with the invention comprises: 
a) a longitudinally axially extending light pipe, and 
b) a lens unit having a light transmitting end wall and structure extending 
away from the end wall generally axially and sidewardly of the light pipe, 
c) the light pipe and the lens unit retained in assembled relation, whereby 
light is transmitted from the light pipe to the end wall. 
It is another important object to provide an interlocking relationship as 
between the lens unit structure and the light pipe; and for this purpose 
the light pipe may have an exterior flange to which the lens unit 
structure couples. Such structure may incorporate multiple spring fingers 
coupling to the flange on the light pipe, the light pipe received into the 
lens structure. 
A further object is to locate the referenced end wall of the lens unit in 
axial alignment with the light pipe, that end wall having light 
transmitting facets. 
A further object is to provide the spring fingers to be spaced about the 
light pipe axis, and to define longitudinally extending gaps therebetween, 
and there being a protrusion on the light pipe extending into one of said 
gaps to engage at least one of the spring fingers and block rotation of 
the pipe relative to the lens unit, about said axis. 
An additional object is to provide the spring fingers with cam surfaces, to 
be spread apart in response to axial movement of the light pipe relative 
to the spring fingers. 
A further object is to provide a light source spaced axially from the light 
pipe and directed axially toward the light pipe. That source may comprise 
an LED; and two panels may be provided, one to support the lens unit and 
the other to support the LED, in fixed spaced relation, whereby the LED 
may be replaced without disturbing the light pipe or lens unit. 
And, yet another object is to provide a method of positioning a lens unit, 
light pipe and light source in coaxial light transmitting relation, that 
includes: 
a) providing a panel, 
b) assembling the lens unit to the panel to project through an opening in 
the panel, 
c) assembling the light pipe and lens unit to position the light pipe 
relative to the lens unit and to also hold the lens unit assembled to the 
panel, 
d) and relatively locating the light source and light pipe to transmit 
light endwise into the light pipe, for transmission through the lens unit. 
These and other objects and advantages of the invention, as well as the 
details of an illustrative embodiment, will be more fully understood from 
the following specification and drawings, in which:

DETAILED DESCRIPTION 
In FIG. 1, a light pipe 10 or fiber optics cable, of relatively short 
length between its opposite ends 11 and 12, is endwise received leftwardly 
into a lens unit 13 to be fixedly positioned coaxially relative to that 
unit. The lens has a light transmitting end wall 14, or lens, and a skirt 
15 integral with that end wall and extending axially rightwardly. The end 
11 of the pipe 10 directly faces 14, which has facets 14a on the end wall 
interior face to receive and diffuse light transmitted axially by the 
short pipe. Note gap at 50, and the leftwardly convex outer surface 14b of 
the lens wall 14, to transmit light as in directions indicated by arrows 
16. 
The lens unit has structure extending away from end wall 14 generally 
axially rightwardly, and sidewardly of the light pipe side wall 10b. That 
structure may be considered as retention structure in the form of like 
spring fingers 20 spaced about the axis 21. Four such fingers may be 
provided, as indicated in FIG. 2. Those fingers have leftward ends 20a 
integral with and projecting rightwardly from skirt 15, as shown, and 
rightward ends to be yieldably resiliently spread apart as the light pipe 
is assembled leftwardly into the lens unit, facilitating ready 
intercoupling of the light pipe and lens unit in intercoupled relation, as 
for example in tongue and groove relation precisely coaxially positioning 
these elements. 
As shown the light pipe has an exterior flange 23 extending about axis 24, 
and the fingers have grooves 26 into which the flange is received upon 
assembly. The groove lengths match the flange length, so that the pipe is 
held in coaxial relation to the lens unit. 
Longitudinally extending gaps 27 are formed between successive spring 
fingers, and a protrusion 28 on the light pipe flange extends radially 
outwardly into one of the gaps. Its sideward engagement with one of the 
fingers blocks relative rotation of the pipe and lens unit, about axis 24. 
The fingers have cam surfaces thereon to be spread apart upon relative 
axial movement of the pipe relative to the fingers. As shown there are 
certain cam surfaces 30 that are divergent in a direction away from the 
lens unit end wall; and there are other cam surfaces 31 that are 
convergent in a direction away from the lens unit end wall. Surfaces 30 
are spread apart as the light pipe is pushed endwise into the lens unit, 
and surfaces 31 are spread apart when the light pipe is displaced endwise 
away from the lens unit. 
FIG. 5 shows a light source such as LED 34 spaced axially from the end 12b 
of the light pipe, and directed toward that end. Accordingly, when LED 34 
is "ON", light is transmitted to and through the light pipe, and through 
the end wall or lens 14. A panel 35 carries the LED at terminals 35a 
connectible to circuitry, and a panel 36 carries the lens unit. Note skirt 
15 close reception in an opening 37 formed in the panel 36, as upon 
initial rightward flexing reception of the lens unit spring fingers 
through that opening. Subsequently, the light pipe 10 is assembled into 
the panel mounted lens unit 13, and into the position shown. Such assembly 
also holds the lens unit spring fingers against the panel bore forming the 
opening 37, whereby a rigid coaxial positioning of the lens unit and light 
pipe relative to the panel 36 is obtained. See also positioning shoulder 
39 formed by the lens unit, and engaging wall 36a of the panel. Mounting 
structure 40 holds the panels 35 and 36 in the positions shown. 
Lens unit 13 may consist of synthetic resinous (plastic) material, which is 
light transparent. 
Lens unit 13 may have rectangular (such as square) cross section, in planes 
normal to axis 24, rather than cylindrical as shown.