Note: Descriptions are shown in the official language in which they were submitted.
CA 02594028 2010-07-19
PIANO-STYLE KEYPAD EMPLOYING A LIGHT GUIDE
BACKGROUND
Field
The disclosed and claimed concept relates generally to keypads for handheld
electronic devices and, more particularly, to a lighted piano-style keypad.
Background Information
Numerous types of handheld electronic devices are known. Examples of such
handheld electronic devices include, for instance, personal data assistants
(PDAs),
handheld computers, two-way pagers, cellular telephones, and the like. Many
handheld
electronic devices also feature a wireless communication capability, although
many such
handheld electronic devices are stand-alone devices that are functional
without
communication with other devices.
Such handheld electronic devices are generally intended to be portable, and
thus
are of a relatively compact configuration. Piano-style keypads typically
provide keys that
have very little space therebetween and derive their name from the keys of a
piano,
which typically are disposed very closely adjacent one another with an
extremely small
space therebetween. Piano-style keypads provide relatively greater numbers of
usable
keys in relatively smaller spaces compared with conventionally-spaced keypads
due to
the very close spacing of the keys of a piano-style keypad. While such piano-
style
keypads have been generally effective for their intended purposes, such piano-
style
keypads have not been without limitation.
Piano-style keypads typically comprise a number of key bodies disposed on a
resilient web, and further comprise key caps adhered to the key bodies. The
web is
deflectable to allow a key body to be translated slightly toward a handheld
electronic
device when a key is being actuated. While the key bodies are typically spaced
apart
from one another on the web, the key caps that are adhered to the key bodies
typically are
disposed very close to one another with minimal space therebetween, thus
providing the
"piano-style" aspect to the keypad.
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A number of competing factors typically bear upon the ultimate design of a
piano-
style keypad. For instance, in order to provide long term reliability of the
key caps
adhered to the key bodies, each key body typically must have an exterior
surface with at
least about fifteen square millimeters of adherable area for adhering of the
key caps to the
key bodies. Additionally, the portion of the resilient web that is peripheral
to a key body
and that is deflectable when a key body is being translated toward the
handheld
electronic device desirably has a radial length, i.e., a length in a direction
pointed away
from the key body in the plane of the web, of at least 0.6 millimeters. Such a
length has
been determined to provide long term reliability while allowing the key bodies
to be
easily actuated and to provide a desirable tactile response during such
actuation.
Some previous keypads have provided a light guide and key bodies formed as a
single component that is molded in a multi-step process. The light guide would
be
formed from a light-transmitting material, such as a clear plastic. The light
guide would
then be positioned in a mold, and uncured resilient material would be poured
into the
mold in contact with the light guide. The resilient material would cure, thus
providing
resilient structures and key bodies molded to the light guide. However, the
size of the
resilient structures was limited by the size of the light guide. That is, for
a given space,
the larger the light guide was, the relatively smaller would be the resilient
structures and
key bodies molded to the light guide.
As the number of piano-style keys within a given area increases, the adherable
surface area of the key bodies and/or the radial length of the web peripheral
to the key
bodies must decrease, but can only be decreased to a certain extent and cannot
be smaller
than the aforementioned dimensions. As such, piano-style keypads of a
particular size
could have only a limited number of keys. It thus would be desirable to
provide an
improved piano-style keypad that overcomes or at least partially alleviates
such
limitations.
BRIEF DESCRIPTION OF THE DRAWINGS
A further understanding of the disclosed and claimed concepts can be gained
from
the following Description when read in conjunction with the accompanying
drawings in
which:
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Fig. 1 is an exploded perspective view of an improved keypad in accordance
with the disclosed and claimed concept;
Fig. IA is a schematic view of an exemplary handheld electronic device
incorporating the improved keypad of Fig. 1;
Fig. 2 is another exploded perspective view of the keypad of Fig. 1;
Fig. 3 is a perspective view of the keypad;
Fig. 4 is another perspective view of the keypad;
Fig. 5 is a perspective view a portion of the keypad;
Fig. 6 is a sectional view as taken along line 6-6 of Fig. 4;
Fig. 7 is a sectional view as taken along line 7-7 of Fig. 4;
Fig. 8 is an enlarged view of the encircled portion of Fig. 7;
Fig. 9 is a view similar to Fig. 8, except showing a key of the keypad in an
actuated position.
Similar numerals refer to similar parts throughout the specification.
DESCRIPTION
In an embodiment, the present disclosure provides a keypad for a handheld
electronic device that comprises a light source. The keypad includes a key
sheet and a
light guide. The key sheet comprises a base and a number of key bodies, at
least some of
the key bodies each being disposed on the base and being movable between an
unactuated
position and an actuated position, the key body in the actuated position being
structured to
complete a circuit of the handheld electronic device, at least a portion of
the key sheet
being translucent. The light guide comprises a frame and a number of supports,
at least a
portion of the frame being disposed adjacent at least a portion of the base,
the supports
extending away from the frame in a common direction, at least some of the
supports
engaging the base to resist movement of the base in a direction transverse to
the common
direction, at least a portion of the light guide being translucent and being
structured to
transmit light between the light source and the key sheet.
The key sheet can comprise a number of receptacles, at least some of the
supports
each being received in a receptacle. The receptacles can be holes formed in
the base, and
the supports can be pegs that protrude from the frame and that are received in
the holes. At
least some of the pegs can each have an interference fit with a hole.
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The base can comprise a web and a leg network, the leg network protruding from
the web and being structured to engage a substrate of the handheld electronic
device, a
portion of the web peripheral to a particular key body being movable between
an
undeflected position and a deflected position, the portion of the web being in
the
undeflected position when the particular key body is in the unactuated
position, the portion
of the web being in the deflected position when the particular key body is in
the actuated
position.
The leg network can comprise a plurality of braces structured to engage the
substrate, the braces being structured to resist movement of a portion of the
web peripheral
to one key body toward its deflected position when a portion of the web
peripheral to an
adjacent key body moves toward its deflected position.
At least some of the braces can each have a hole formed therein, and the
supports
can be pegs that protrude from the frame and that are received in the holes,
at least some
of the key bodies being movable along a direction between the unactuated and
actuated
positions, and wherein the pegs protrude along the direction from the frame,
the pegs
resisting movement of the braces transverse to the direction.
The key sheet can further comprise a number of key caps, at least some of the
key
caps each being adhered to a key body. The light guide frame can have a number
of
openings formed therein, at least some of the key bodies each being disposed
within an
opening. At least a portion of the frame can be disposed between the base and
the key
caps.
At least a portion of the light guide can overlie at least a portion of the
base. At
least a portion of the web can be disposed between the leg network and at
least a portion
of the light guide. The portion of the web peripheral to the particular key
body can extend
between the particular key body and at least a portion of the leg network.
The portion of the web that is movable between the undeflected and deflected
positions can have at least about 0.6 millimeters between the particular key
body and the
at least portion of the leg network. The key bodies can each have a mounting
surface, at
least some of the key caps each being adhered to the mounting surface of a key
body, each
mounting surface having an area of at least about fifteen square millimeters.
The mounting
surfaces can be substantially planar.
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The keypad can further comprise a substrate, and the light guide can comprise
a
number of retention members, at least some of the retention members each being
engaged
with the substrate. At least a portion of the key sheet can be disposed
between at least a
portion of the light guide and at least a portion of the substrate.
At least some of the retention members can each comprise a latch that is
engaged
with the substrate. The retention members can extend away from the frame in
the common
direction. The base can have a number of holes formed therein, and wherein the
supports
are pins received in the holes, the pins resisting movement of the base in a
direction
transverse to the common direction.
An improved keypad 4 is depicted generally, in whole or in part, in Figs. 1
and 2-9.
The improved keypad 4 is a piano-style keypad that can be employed in a
handheld
electronic device 6, such as is depicted schematically in Fig. IA. The
exemplary
handheld electronic device 6 comprises an input apparatus 8, a processor
apparatus 10,
and an output apparatus 12. The keypad 4 is a component of the input apparatus
8. The
processor apparatus 10 is structured to receive input from the input apparatus
8 and to
provide output to the output apparatus 12.
As can be understood from Fig. 1, the keypad 4 comprises a light guide 16 and
a
key sheet 20. In the exemplary depicted embodiment of the keypad 4, the light
guide 16
mounts the key sheet 20 to a substrate 24, such as a printed circuit board of
the handheld
electric device 6. At least a portion of the key sheet 20 is translucent, as
is at least a
portion of the light guide 16. As employed herein, the expression
"translucent" and
variations thereof shall refer broadly to a quality that permits the passage
of light and
may include a transparent quality wherein light is transmitted without
appreciable
scattering so that it does not meaningfully alter light waves traveling
therethrough. The
light guide 16 is configured to transmit light from a light source, such as a
number of
LEDs 28 on the substrate 24, to the key sheet 20 to provide illumination of
the keys 42
(Fig. 4) of the keypad 4. As employed herein, the expression "a number of' and
variations thereof shall refer broadly to any nonzero quantity including a
quantity of one.
As can be further seen from Fig. 1, the key sheet 20 comprises a resilient
base 32
upon which are disposed a number of key bodies 36. The key sheet 20
additionally
includes a number of key caps 40. Each key body 36 has a mounting surface 44
that is
substantially planar, for example, and the key caps 40 are adhered to the
mounting
CA 02594028 2010-07-19
surfaces 44. As employed herein, the expression "adhered" and variations
thereof shall
refer broadly to a situation in which two solids are fastened together such as
by the use of
glue, cement, other adhesive, or through to use of a fusion or other joining
process, and
between which an adhesive bond or other fusion bond has been created. A key
body 36
and a key cap 40 together form a key 42 (Fig. 4) of the keypad 4. The keypad 4
is
advantageously configured such that each mounting surface 44 has an adherable
area of
at least fifteen square millimeters. In the present exemplary embodiment, the
mounting
surfaces 44 generally each have an adherable area of at least about twenty
square
millimeters.
Each key body 36 has an actuator 48 (Figs. 2 and 3) protruding therefrom
opposite
the mounting surface 44. Each key body 36 is movable between an unactuated
position,
such as is depicted generally in Fig. 8, and an actuated position, such as is
depicted
generally in Fig. 9. In the actuated position, the actuator 48 engages a dome
52 that is
disposed on the substrate 24, and as a result completes an electrical circuit
of the
handheld electronic device 6. The closing of such a circuit can provide, for
example, an
input to the processor apparatus 10.
As can be understood from Figs 2 and 3, the base 32 comprises a web 56 and a
leg
network 60. The key bodies 36 can generally be said to be disposed on the web
56. The
leg network 60 protrudes from the web 56 and is engaged with the substrate 24.
As can
be understood from Figs 8 and 9, the portion of the web 56 that is peripheral
to any given
key is movable between an undeflected position, such as is depicted generally
in Fig. 8,
and a deflected position, such as is depicted generally in Fig. 9, when the
given key body
36 is moved between its unactuated and actuated positions. The portion of the
web 56
peripheral to a given key body 36 is in an undeflected position when the key
body 36 is
in an unactuated position, such as depicted generally in Fig. 8, and such
portion of the
web 56 is in a deflected position when the given key body 36 is in an actuated
position,
such as is depicted generally in Fig. 9.
The leg network 60 comprises a plurality of legs 64 and a plurality of islands
68.
The legs 64 extend between the islands and generally each are formed to
include a notch
72 that allows the passage of air from the region between a specific key body
36 and the
substrate 24 when the specific key body 36 is moved toward the actuated
position.
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The islands 68 generally each have a hole 76 formed therein that serves as a
receptacle
for a support structure of the light guide 16. The islands 68 are of a cross
section in a
plane transverse to the plane of the substrate 24 that is relatively larger
than a similarly
oriented cross sectional area of a leg 64. The islands 68 advantageously
resist the
deformation of the portions of the web 56 adjacent a particular key body 36
when the
particular key body 36 is moved between the unactuated and actuated positions.
The light guide 16 includes a frame 78, a number of supports 80, and a number
of
retention members 88. The frame 78 has a number of openings 90 formed therein.
The
key bodies 36 are disposed within the openings 90. The supports 80 are in the
form of
pins that protrude from the frame 78 in a direction indicated by the axis 92
in Fig. 2. The
supports are receivable in the holes 76, as indicated above, to provide
support to the key
sheet 20 and to resist movement of the key sheet 20 in directions transverse
to the
axis 92.
The supports 80 in the exemplary depicted embodiment, as can be seen in Fig.
2,
are of two types. Specifically, the supports 80 include a number of first
supports 82 that
are of a generally cylindrical configuration and a number of second supports
84 that are
generally of a frusto-conic, i.e., truncated cone, configuration. The first
supports 82 are
receivable with an interference fit in the holes 76. The second supports 84
are receivable
in the hole 76 with a generally clearance fit. The first supports 82 provide a
relatively
greater degree of support to the key sheet 20 than the second supports 84,
although the
number of first supports 82 is limited in order to limit the force required to
assemble the
keypad 4.
Each retention member 88 comprises a shank 86 protruding from the frame 78 and
a latch 94 disposed at a free end of the shank 86. The shanks 86, and thus the
retention
members 88, protrude from the same face of the frame 78 as the supports 80 and
extend
from the frame 78 along the axis 92.
The light guide 16 additionally has a number of recesses 96 formed therein and
within which the light sources 28 are disposed when the keypad 4 is in an
assembled
condition, such as is depicted generally in Figs. 4 and 6. As can be further
be seen in
Fig. 4, the key caps 40 are closely spaced, meaning that the space between
adjacent key
caps 40 is very small when compared with the dimensions of each key cap 40,
and
typically will be no more than about ten percent of a given dimension of a key
cap 40, for
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example, it being noted that the spacing between the key caps 40 depicted in
Fig. 4 is
greatly exaggerated.
The latches 94 engage an underside of the substrate 24, i.e., a surface of the
substrate 24 opposite that on which the domes 52 are disposed. The engagement
of the
latches 94 of the light guide 16 with the substrate 24 retains the key sheet
20 mounted to
the substrate 24 and disposed generally between the frame 78 and the substrate
24. More
particularly, the base 32 is generally interposed between the frame 78 and the
substrate
24. As indicated above, the supports 80 of the light guide 16 received in the
holes 76
provide support to the key sheet 20 and resist movement of the key sheet 20 in
directions
transverse to the axis 92. The light guide 16 thus retains the key sheet 20 on
the substrate
24 and transmits light from the light sources 28 to the key sheet 20.
As can be understood from Fig. 9, the portions of the web 56 that are
peripheral to
a particular key body 36 have a radial distance between the key body 36 and
the leg
network 60 that is at least 0.6 millimeters, as is indicated by the dimension
98. Such a
dimension 98 allows for easy actuation of the key bodies 36, desirable tactile
feedback to
the user, and long-term reliability.
As can be further understood from Figs 8 and 9, leg network 60 is disposed
generally between the web 56 and the substrate 24. Moreover, it can be seen
that the
frame 78 is disposed generally between the key caps 40 and the web 56.
Many of the key bodies 36 are configured such that the mounting surface 44
thereof, such as are depicted generally in Fig. 5, generally each have gross
dimensions of
roughly 4.0 millimeters by 5.0 millimeters, thereby enabling the mounting
surface 44 to
have an adherable area of about 20.0 millimeters. As can be understood from
Fig. 6, the
supports 80 engage the web 56 and also engage the substrate 24.
The improved keypad 4 is thus configured in a fashion whereby the light guide
generally does not serve as a limiting factor in the design of the keypad,
which permits a
relatively large number of keys 42 to be provided in a relatively small area.
For instance,
the keypad 4 could be a full QWERTY, QWERTZ, AZERTY, etc., keypad on a
handheld
electronic device, such as the handheld electronic device 6, without the
handheld
electronic device being of an undesirably large size. The improved keypad 4
additionally
provides a key sheet 20 that is supported by a light guide 16, which resists
unintended
movement or slumping of the key sheet 20, and which further contributes to the
ability of
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the keypad 4 to provide a large number of keys 42. The islands 68
advantageously resist
unintended closing of circuits of the handheld electronic device 6, and thus
resists
unintended input to the processor apparatus 10, by mechanically isolating a
portion of the
web 56 from moving toward its deflected position when an adjacent key body 36
is
moved to its actuated position.
While specific embodiments of the disclosed and claimed concept have been
described in detail, it will be appreciated by those skilled in the art that
various
modifications and alternatives to those details could be developed in light of
the overall
teachings of the disclosure. Accordingly, the particular arrangements
disclosed are meant
to be illustrative only and not limiting as to the scope of the disclosed and
claimed
concept which is to be given the full breadth of the claims appended and any
and all
equivalents thereof.
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