U.S. patent number 3,887,791 [Application Number 05/414,004] was granted by the patent office on 1975-06-03 for prismatic display window for a calculator.
This patent grant is currently assigned to Texas Instruments Incorporated. Invention is credited to Lee Glen Kitchens.
United States Patent |
3,887,791 |
Kitchens |
June 3, 1975 |
Prismatic display window for a calculator
Abstract
Disclosed is a calculator casing having a prism display window
for shifting the angle of light transmission therethrough to
provide a more desirable viewing angle. A low profile calculator
having a liquid crystal, light emitting diode, or gas discharge
tube display has interposed between the viewer and the display
elements a prism window for shifting the viewing angle and
filtering undesirable ambient light.
Inventors: |
Kitchens; Lee Glen (Richardson,
TX) |
Assignee: |
Texas Instruments Incorporated
(Dallas, TX)
|
Family
ID: |
23639553 |
Appl.
No.: |
05/414,004 |
Filed: |
November 8, 1973 |
Current U.S.
Class: |
235/1D; D18/7;
177/177; 359/438; 359/609; 345/50; 349/57 |
Current CPC
Class: |
G06C
11/02 (20130101) |
Current International
Class: |
G06C
11/00 (20060101); G06C 11/02 (20060101); G06c
005/02 (); G06m 001/22 () |
Field of
Search: |
;235/1D,1A
;177/177-178,182 ;58/5R ;116/DIG.36 ;340/365R,337,380 ;D52/2,3
;D26/5C |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tomsky; Stephen J.
Attorney, Agent or Firm: Levine; Harold Grossman; Rene E.
Devine; Thomas G.
Claims
I claim:
1. In a calculator system having a keyboard and having a visible
output display contained in a casing for displaying visual data
representations, the improvement comprising:
a. a display source, disposed substantially in the same plane as
the keyboard; and
b. a prism attached to the casing for altering the angle of
transmission of the visual data representations the transmission
angle being acute with respect to the vertical plane.
2. The calculator system according to claim 1 wherein said prism is
shaped as a trapezoid.
3. The calculator system according to claim 2 further comprising a
magnifying lens overlying the display source.
4. The calculator system according to claim 3 wherein the
transmission angle with respect to the vertical plane is less than
20.degree..
5. The calculator system according to claim 4 wherein said prism is
comprised of plastic.
6. The calculator system according to claim 1 wherein said prism
further provides an optical filter.
Description
This invention relates to calculator casing in general and more
specifically to calculator casing having a prism lens overlying the
display source for shifting the viewing angle thereof.
BACKGROUND OF THE INVENTION
With the arrival of the calculator age, there have been provided
calculators suitable for nearly any and all tasks. The more complex
the task, the more complex the calculator which is required, and
such complex calculators have been implemented as bulky
non-portable desk-top models. Less sophisticated machines are
presently provided in smaller desk-top models which are easily
transported. Still less sophisticated machines are provided in
portable hand-held casings which may even be of the pocket size
variety yet which are still convenient to operate. Two such
hand-held calculators are described in detail in copending patent
application "Variable Function Programmed Calculator," Ser. No.
163,565, now abandoned and replaced by Ser. No. 420,999, filed Dec.
3, 1973 and "Multi-Chip Calculator System," Ser. No. 397,060, filed
Sept. 13, 1973, both of which are assigned to the assignee of this
application. A casing preferably utilized with the calculator
system described in Ser. No. 420,999 is disclosed in U.S. Design
Pat. No. 226,922 entitled "Calculator Casing," filed in June 9,
1972. In such a calculator casing having a relatively high profile,
it is observed that the display surfade of surface source lies at a
relatively elevated angle to the plane of the keyboard for
providing a pleasant viewing angle to the plane of the keyboard for
providing a pleasant viewing angle for the user. Such elevation,
however, requires increased height dimensions of the calculator
casing and as such is not suitable for a low profile design.
A calculator display panel for use on a hand-held calculator of the
low profile type is set forth in U.S. Design Pat. No. 227,261. It
is there observed that the display window and the keyboard lie
substantially in the same plane. Such a relationship between the
plane of the display and the plane of the keyboard requires a near
perpendicular viewing angle by the user which is inconvenient and
generally undesirable. other calculator systems are available for
magnifying smaller display sources, but fail to alter the angle of
light transmission.
It is therefore an object of the present invention to provide a
calculator casing having a prism for shifting the angle of
transmission of the display. it is another object of the present
invention to provide a calculator system of the type having a
visible display output contained in a casing which features a prism
overlying the display figures to alter the angle of light
transmission of the figures and thereby provide an improved viewing
angle. It is still another object of the present invention to
provide such a prism in a calculator system overlying visual
representations formed by light emitting diodes, liquid crystals,
or gas discharge tubes. It is still another object of the present
invention to provide a calculator with light sources of a display
lying substantially in the plane of the keyboard having an
overlying prismatic window which has only surface thereof lying
flush with the calculator casing for altering the transmission
through the window of the display images.
Briefly and in accordance with the present invention, the display
of a calculator system includes a prism overlying the display
output source for altering the angle of transmission of the display
representations and thereby providing an improved viewing angle for
the user. In the preferred embodiment, the prism is trapezoidal in
shape and overlies a display source comprised of liquid crystals,
light emitting diodes, or gas discharge tubes lying substantially
in the plane of the keyboard. The prism further provides an optical
filter having a visual band pass centered about the characteristic
frequency of the display source. To provide an attractive low
profile version, the back end of the top surface of the prism is
flush with the keyboard casing, with the front end elevated to form
a small angle within the keyboard and display source which lie in a
common plane. The angle of transmission of the output data
characters, however, is at an increased angle bent towards the
viewer.
The novel features believed to be characteristic of this invention
are set forth in the appended claims. The invention itself,
however, as well as other objects and advantages thereof, may best
be understood by reference to the following detailed description
when read in conjunction with the accompanied drawings wherein:
FIG. 1 pictorially depicts a calculator system featuring a prism
display window;
FIG. 2 depicts a profile view of the calculator and display shown
in FIG. 1; and
FIGS. 3a and 3b depict a preferred embodiment of the prism of this
invention.
DETAILED DESCRIPTION
Referring now to FIG. 1, there is shown an electronic calculator
featuring a prismatic display window according to this invention.
The calculator 1 is one of low profile and preferably of the
hand-held version. The electronics of the calculator in FIG. 1 is
explained in detail in copending patent application Ser. No.
397,060, filed Sept. 13, 1973 and assigned to the assignee of this
invention. The calculator has a keyboard 2 for entering data and
instructions into the calculator for effecting manipulations
thereof. The results are displayed on the display 3 through the
prismatic window 4 of this invention which is also shown as
removed. The window 4 is attached to the casing of the calculator
via a series of tabs or protrusions which will be described
subsequently. The display 3 may be of the visible light emitting
diode type, or of the gas discharge tube type, or of the liquid
crystal type. The prismatic window 4, depending on the specific
display type, is constructed so as to provide an appropriate filter
having an optical band pass centered around the respective light
source. For example, when conventional VLEDs are utilized, then a
red filter is provided and when gas discharged tubes are utilized,
an orange filter is provided. When the utilizing liquid crystals,
the prismatic window is clear and a filter is not utilized.
Constructing the window 4 of various translucent acrylic plastics
so as to provide the above described filters is generally well
known.
Referring now to FIG. 2, there is shown a silhouette and partial
sectional of view A--A of the calculator in FIG. 1. A printed
circuit board 12 has both the keyboard with keys 13 and the display
source 5 mounted thereon. The plane of the keyboard lies
substantially at an angle .theta. with the bottom of the casing of
the calculator which is the horizontal ground reference. The angle
.theta. may be designed according to preference, but to achieve the
low profile effect, the angle .theta. preferably is less than
10.degree., and preferably is 4.degree.. Overlying the display
source 5 is a magnifying lens 11 for virtually enlarging the output
data images. The upper surface of the prismatic window lies in the
surface of the keyboard housing with the normal thereto forming the
angle .PHI. with the vertical. The angle .PHI. may be designed
having magnitude according to preferance, but to achieve the low
profile effect, only a minimum elevation or minimum .PHI. may be
utilized. In this embodiment .PHI. is approximately 9.degree.. The
angle of the prism is denoted .beta. and is approximately
9.5.degree. in this embodiment. The total angle of transmission of
the output display is (.PHI. + .beta.) or approximately
13.5.degree. from the vertical. Conventional non-prismatic windows
would provide an angle of .PHI. or 4.degree., which is
insufficient. As long as an optical quality lens is utilized and
the angles are small, the angle at which the light passes through
the window is determined principally by the angles and the index of
refraction is not critical.
Shown in FIG. 3a is a detailed magnified view of the back of the
display window. Tabs 6 project downwardly for hooking beneath the
case of the calculator for holding the window securely. From the
end view of the window, it is seen that the window is generally of
a trapezoidal configuration, whereby the lower surface of the
window lies at the angle .beta. with the upper surface as above
described.
Shown in FIG. 3b is the front view of the window shown in FIG. 3a
as viewed from the keyboard. Nodes 7 extend therefrom for insertion
into the calculator casing which in combination with tabs 6 hold
the window 4 securely in place.
The dimensions of the window 4 depend generally upon the dimensions
of the calculator, but in one embodiment the rear of the window as
measured between points 9 is approximately 2.6 inches and sides 8
extend from points 9 at an angle of 4 degrees outward. Side 10 of
the display is substantially 0.445 inches from the back side of the
window 4 defined between points 9. The thickness at the back edge
is approximately 0.05 inches. The angle .beta. is approximately 9.5
degrees which defines the height at the front of the window to be
approximately 0.125 inches.
Preferably the window 4 is comprised of the plastic Lexan, but any
similar translucent acrylic plastic may be utilized. The plastic is
preferably of optical quality, and as long as the angles are small,
the particular index of refraction is not a critical feature. To
implement the filter as above described, the translucent acrylic
plastic is constructed of the appropriate color so as to pass
substantially only the color characteristic of the display source
lying beneath the window. The lens 4 is preferably constructed
utilizing injection molding processes keeping the mold surfaces of
optical quality. These processes are now well known in the art.
It is thus evident that a prismatic display window is provided
which is advantageously utilized in a calculator system. The
prismatic display window allows a low profile calculator without an
extremely elevated keyboard angle by altering the angle of light
transmission from the display source lying beneath the window. By
providing a filter in the display window, background light which
may hinder viewing of the display is substantially eliminated. By
utilizing the prismatic window of this invention, a viewing angle
of approximately 13.5.degree. from the vertical is achieved while
the keyboard and the display source lies at an angle of less than
5.degree. with the horizontal.
While a specific embodimnt of a prismatic window for a calculator
system has been described in detail herein, it will be apparent to
those skilled in the art that various changes of shape,
composition, and dimensions may be made without departing from the
spirit or scope of this invention.
* * * * *