U.S. patent number 3,786,499 [Application Number 05/307,280] was granted by the patent office on 1974-01-15 for alpha-numeric display package.
This patent grant is currently assigned to Fairchild Camera and Instrument Corporation. Invention is credited to Ernest J. Funk, Alfred S. Jankowski, John L. Moll.
United States Patent |
3,786,499 |
Jankowski , et al. |
January 15, 1974 |
ALPHA-NUMERIC DISPLAY PACKAGE
Abstract
A package for displaying alpha-numeric characters using a
plurality of discrete, light-emitting diodes, each diode providing
a point source of light corresponding to one of the segments of the
characters when electrically activated, including a substrate
having the light-emitting diodes mounted upon it; a block of
material adjacent the substrate containing a plurality of light
pipes in the shape of the segments; and a composite fly's eye lens
on top of the light pipes for displaying the selected character by
the selective activation of the light-emitting diodes.
Inventors: |
Jankowski; Alfred S. (San Jose,
CA), Moll; John L. (Stanford, CA), Funk; Ernest J.
(Cupertino, CA) |
Assignee: |
Fairchild Camera and Instrument
Corporation (Mountain View, CA)
|
Family
ID: |
23189034 |
Appl.
No.: |
05/307,280 |
Filed: |
November 16, 1972 |
Current U.S.
Class: |
340/815.42;
313/500; 313/512; 345/46; 340/815.54; 340/815.45 |
Current CPC
Class: |
H05B
33/12 (20130101); H01L 33/00 (20130101); H05B
33/02 (20130101) |
Current International
Class: |
H05B
33/12 (20060101); H01L 33/00 (20060101); H05B
33/02 (20060101); G08b 005/36 () |
Field of
Search: |
;340/380,381,366R,378R
;313/109.5,92LF |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Trafton; David L.
Attorney, Agent or Firm: Borovoy; Roger S. MacPherson; Alan
H.
Claims
We claim:
1. A package for selectively displaying one of a plurality of
alpha-numeric characters using a plurality of discrete,
light-emitting diodes, each diode providing a point source of light
corresponding to a segment of said characters when electrically
activated, comprising:
a substrate having arranged laterally thereupon a plurality of
light-emitting diodes in the general shape of the necessary
segments of all the alpha-numeric characters to be displayed;
a single block of material adjacent said substrate having two
opposed parallel faces, the first face lying adjacent to said
substrate;
a plurality of light pipes in the shape of said character segments
extending completely through said block from said first face to the
opposite one, a different one of said pipes being aligned with a
corresponding one of said diodes, the walls of each light pipe
being reflective, whereby the light emitted from each electrically
activated diode is passed through its corresponding light pipe;
and
a composite lens covering the second opposite face of said block,
said lens comprising a plurality of fly's eye lenses in close
proximity with each other, said composite lens at least covering
the ends of all of said light pipes where they extend to said
second opposite face, whereby the light from each electrically
activated light-emitting diode is passed through its corresponding
light pipe and then through said composite lens, thereby optically
displaying on said lens all the segments of the alpha-numeric
character selected by the electrical activation of one or a
plurality of said light-emitting diodes.
2. The package of claim 1 further characterized by said block being
plastic.
3. The package of claim 2 further characterized by the walls of
said light pipes being covered with a reflective metal.
4. The package of claim 1 further characterized by the surface of
said substrate adjacent said block having a non-reflective,
insulating layer surrounding said light emitting diodes.
5. The package of claim 3 further characterized by said
non-reflective coating being an insulating material.
6. The package of claim 1 further characterized by the segments of
said characters being arranged in the shape of a composite
digit.
7. The package of claim 6 further characterized by said composite
digit including a decimal point.
8. The package of claim 1 further characterized by said second
opposite face of said block having a non-reflective coating.
Description
FIELD OF THE INVENTION
This invention is in the field of packages for solid state
displays. More specifically, the packages of this invention are the
form of hybrid circuits having a plurality of light-emitting diodes
mounted on a base, along with a self-contained packaging system to
display the emitted light in the form of an alpha-numeric
character.
PRIOR ART
Packages used for displaying alpha-numeric characters from a
plurality of light-emitting diodes mounted on a substrate are known
in the art. These packages generally employ a plurality of
translucent, plastic plugs in the shape desired for each segment of
the alpha-numeric character. The light from an activated diode is
passed through the plastic segment, lighting up the translucent
material of the plastic and creating the luminescent display of
that digit segment. Because of the translucent character of the
plastic, no lensing system is required. The combination of all the
lighted segments makes up the desired character. The primary
difficulty with these prior art packages is the inefficiency of the
transmission of the tiny amount of light from each light-emitting
diode through the translucent plastic. Accordingly, a more
efficient system had to be developed.
BRIEF DESCRIPTION OF THE INVENTION
This invention is a package for selectively displaying one of a
plurality of alpha-numeric characters using a plurality of
discrete, light-emitting diodes, each diode providing a point
source of light corresponding to a segment of the characters when
electrically activated. The invention includes a substrate having
arranged laterally thereupon a plurality of light-emitting diodes
in the general shape of the necessary segments of all the
alpha-numeric characters to be displayed; a single block of
material adjacent to the substrate having two opposed parallel
faces, the first face lying adjacent to the substrate; a plurality
of light pipes in the shape of the character segments extending
completely through the block from the first face to the opposite
one, a different one of the light pipes being aligned with a
corresponding one of the diodes, the walls of each light pipe being
reflective, whereby the light emitted from each electrically
activated diode is passed through its corresponding light pipe; and
a composite lens covering the second opposite face of the block,
the lens comprising a plurality of fly's eye lenses in close
proximity with each other, the composite lens at least covering the
ends of all the light pipes where they extend to the second
opposite face, whereby the light from each electrically activated
light-emitting diode is passed through its corresponding light pipe
and then through the composite lens, thereby optically displaying
on the lens all the segments of the alpha-numeric characters
selected by the electrical activation of one or a plurality of the
light-emitting diodes.
While light pipes have been used in the past for light transmission
of bright incandescent lamps, a system has not been found for using
light pipes with sufficient light transmission efficiency for the
tiny amount of emitted light from a light-emitting diode. In this
invention, it was unexpectedly found that the combination of a
light pipe having reflective walls and which is covered at the
display end of the pipe with a fly's eye lens provides a very
efficient means of displaying light from these tiny, light-emitting
diodes. This unique combination of the invention provides a vast
improvement over the prior art light-emitting diode packages using
translucent plastic. Moreover, it is inexpensive and simple to mass
produce.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of the substrate of the invention;
FIG. 2 is a top view of the block which contains the light pipes of
the invention;
FIG. 3 is an end, interior view (with the end of the package
removed) of the package of the invention; and
FIG. 4 is a cross-sectional view through the lines 4--4 of FIG.
2.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, and in particular to FIG. 1, each of the
light-emitting diodes 11, 12, 13, 14, 15, 16 and 17 are mounted
with their light-emitting side up on a conductive metal plate 18.
These diodes are arranged laterally upon the substrate in the
general shape of the necessary segments of all the alpha-numeric
characters to be displayed. In the selected embodiment of the
invention, diodes 11, 12, 14, 15, 16 and 17 are arranged to
correspond with the segments of a figure eight (as shown in FIG.
2). As is well known in the art, a seven-segment figure eight, by
the selective activation of two or more diodes, is sufficient to
display all of the digits zero through nine. Diode 13 is used to
display the decimal point. This segment arrangement is conventional
in the art, and needs no further explanation here.
The first electrical connection to each diode is a common
connection which results from the soldering of each diode to the
common metal plate 18 on substrate 10, as shown in FIG. 1. The
other electrical connection is a separate connection for each diode
(for selective electrical activation) in the form of a wire 19 from
the top surface of each diode to a conductive post 20. Posts 20
extend, as shown in FIG. 3, out from the bottom of the package for
plug-in electrical connection to a conventional printed circuit
board. Preferably, the surface of the metal plate 18 is covered,
surrounding the diodes, with an opaque, insulating layer, such as
black paper, to prevent shorting of wires 19 against the metal. The
opaqueness prevents unwanted light reflections.
The single block of material containing the light pipes of this
invention is shown in FIGS. 2 and 4. Block 21, preferably made of
plastic, has a first lower face 22 which is located adjacent to the
top surface of substrate 10 atop the light-emitting diodes, as
shown in FIG. 3. Block 21 has a second opposed parallel face 23,
shown in FIG. 2, upon which the light passing through light pipes
24 is displayed. Block 21 contains a plurality of light pipes 24 in
the shape of the desired character segments. Referring to FIGS. 2
and 4, these segments extend completely through block 21 from the
first face 22 to the opposite face 23. A different one of the light
pipes 24 is aligned with each of the light-emitting diodes 11-17
shown in FIG. 1. The interior walls of each light pipe 24 are
reflective. This reflectivity is preferably achieved by coating the
interior walls of each light pipe with a reflective material,
preferably a reflective metal such as gold. Although gold is
expensive, it is one of the most highly reflective metals
available. With the construction of block 21 shown in FIGS. 2 and
4, the light emitted from each electrically activated diode is
efficiently passed through its corresponding light pipe 24 and
displayed as a lighted segment on surface 23 of block 21. For
optimum efficiency, it has been found advantageous to coat the
surface 23 with a non-reflective coating surrounding the exposed
segments 24.
However, without the lens cap 25 shown in FIG. 3, the amount of
light displayed at the surface 23 of block 21 does not appear as
individual segments, but as a "hot spot" in the center of each
light pipe. Accordingly, a composite lens cap 25 is employed
covering the second face 23 of block 21. This lens cap comprises a
plurality of fly's eye lenses 26 in close proximity with each
other. The effect of the lens cap is to spread out the displayed
light so that the segments are entirely illuminated. The composite
lens 25 at least covers the ends of light pipes 24 where they
extend to the second face 23 as shown in FIG. 2. In other words,
lens cap 25 must contain a sufficient area of fly's eye lenses 24
to at least cover the entire figure eight and the decimal point 27
shown in FIG. 2. In the embodiment of the invention shown, the
fly's eye lenses 26 are directly molded into cap 25 which is made
of translucent plastic. The plastic material can be white, red,
clear, frosted, or any color desired in the application of the
display. Lens cap 25 fits tightly over the sides of substrate 10 as
shown in FIG. 3, to form a complete enclosure.
The light from each electrically activated light-emitting diode
11-17 shown in FIG. 1, is passed through its corresponding light
pipe 24, shown in FIGS. 2 and 4, and then through the composite
lens 25, shown in FIG. 3, thereby optically displaying on the lens
cap 25 all the segments of the alpha-numeric character selected by
the electrical activation of one or a plurality of light-emitting
diodes. For example, if all of the light-emitting diodes 11-17 are
electrically activated, all of the segments 24 shown in FIG. 2 and
the decimal point 27 will be lighted, displaying the figure "eight"
followed by a decimal point. If all the diodes except diodes 11 and
12, corresponding to the two lower left ones of segments 24 in FIG.
2 (one vertical and one horizontal) are lighted, the character
displayed will be a figure nine followed by a decimal point.
Obviously, if diode 13 (FIG. 1) is not activated, the decimal point
27 (FIG. 2) will not be displayed.
Obviously the invention is applicable to the display of characters
denoting letters of the alphabet, numbers, Chinese or Japanese
characters, or any other lateral configuration of segments 24 (and
corresponding lateral arrangement of the light-emitting diodes on
the substrate 10), using the proper selective activation of the
diodes to activate the designated character for display. These
techniques are well known in the art.
* * * * *