Illumination – Illuminated scale or dial – Edge illuminated modifier or light rod/pipe
Reexamination Certificate
2001-09-19
2003-11-11
Sember, Thomas M. (Department: 2875)
Illumination
Illuminated scale or dial
Edge illuminated modifier or light rod/pipe
C362S035000, C200S314000
Reexamination Certificate
active
06644822
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a light diffusion unit used for a portable electronic communication terminal, for instance.
2. Description of the Related Art
A portable electronic communication terminal such as a cellular phone is designed to include a light diffusion unit for introducing a light emitted from a light source such as a light-emitting diode (LED), to lens, a button or liquid crystal. A portable electronic communication terminal is recently required to be thinner and thinner, and lighter and lighter in weight. Accordingly, a light diffusion unit is also required to be as small as possible. To this end, for instance, an attempt has been made to form a light guide thinner for uniformly introducing a light emitted from a light source, to the light guide.
FIG. 1
is a cross-sectional view of a conventional light diffusion unit.
The illustrated light diffusion unit
101
is comprised of a substrate
105
, a case
106
formed with a hole
106
a
and covering the substrate
105
therewith, a light source
104
mounted on the substrate
105
, a light diffuser
103
arranged in the hole
106
a
of the case
106
for externally radiating a light emitted from the light source
104
, and a light guide
102
arranged between the substrate
105
and the light diffuser
103
for introducing a light emitted from the light source
104
, to the light diffuser
103
.
In operation of the light diffusion unit
101
, when the light diffuser
103
is downwardly pushed, the light guide
102
is deformed, resulting in that a projection formed on a lower surface of the light guide
102
pushes a switch
108
formed on the substrate
105
. As a result of the switch
108
being pushed, the light source
104
is turned on, and hence, emits a light. The light source
104
emits a light not only when the switch
108
is pushed, but also when a call is transmitted or received, and a battery is being charged.
A light emitted from the light source
104
is introduced into the light guide
102
, and is diffused in the light guide
102
. Then, the thus diffused light illuminates the light diffuser
103
exposed out of the case
106
.
In order for the substrate
105
not to be seen through the light diffuser
103
, the substrate
105
and the switch
108
are covered with a sheet
107
. The sheet
107
is composed of a material which reflects and/or diffuses a light, and assists a light to be diffused in the light guide
102
.
However, if the light guide
102
does not have a sufficient thickness, a light emitted from the light source
104
is not adequately diffused in the light guide
102
, resulting in that the light diffuser
103
cannot be uniformly illuminated. For instance, only an area of a surface of the light diffuser
103
, closer to the light source
104
, is only made bright, and, in contrast, an area of a surface of the light diffuser
103
, remoter from the light source
104
, is made dark. The light diffuser
103
would have greater uniformity in brightness such as mentioned above, if the light diffuser
103
had a greater surface area.
It would be quite difficult to solve the above-mentioned problem only by adding the sheet
107
. It would be necessary to increase the number of a light source such as LED in order to introduce a greater amount of light to the light diffuser
103
.
However, an increase in the number of a light source newly causes another problem of increased consumption of power.
Furthermore, if the light guide were designed to have a greater thickness, the light diffusion unit would be thicker, which is contradictory to the above-mentioned requirement that a portable electronic communication terminal is required to be thinner and lighter.
Japanese Unexamined Patent Publication No. 7-58815 has suggested an operating unit in a cellular phone, including a cabinet in which a main substrate is arranged and which is formed at an outer surface thereof with a recessed portion, a control substrate on which a plurality of contacts are formed by printing, and on which a light-emitting device is mounted, a sheet composed of light-permeable and elastic material, and having key tops defined by light-impermeably printing the sheet such that figures and letters remain not printed in areas in alignment with the contacts, and a cover formed with openings in alignment with the key tops, and formed with ribs for pushing the sheet.
Japanese Unexamined Patent Publication No. 2000-30561, which is based on French patent application No. 9803142, has suggested a contact detecting device including a first insulating film defining at least one dome having an inner surface on which a contact electrode layer is formed, and an outer surface, and a second insulating film supporting thereon a detecting circuit which detects whether the contact electrode layer is electrically connected thereto. A layer composed of electroluminescence material is formed directly on the first insulating film such that the layer is positioned on a flat surface surrounding the outer surface.
Japanese Unexamined Patent Publication No. 7-273854 has suggested a cellular phone including a key top plate composed of light-permeable synthetic resin. The key top plate is formed with upwardly projecting key tops. The key top plate is arranged at a rear of a case of the cellular phone such that key tops are exposed through holes formed with the case. A light-emitting diode is mounted on a lower surface of the key top plate. A light emitted from the light-emitting diode is introduced through the key top plate to the key tops for illuminating the key tops. A mirror-like reflection layer is formed either on a surface of the key top plate except the key tops, or on a rear surface of the case. As an alternative, the key top is covered at a surface thereof except the key tops with a mirror-like reflection sheet. A light having been introduced into the key top plate and having been reflected at the reflection layer or the reflection sheet is introduced into the key tops.
Japanese Unexamined Patent Publication No. 9-198902 has suggested a key illuminator in a cellular phone, including keys to be pushed by a user, formed at a lower surface thereof with a projection, and at least partially light-permeable between upper and lower surfaces, a case formed with windows in which the keys are arranged, a switch transmitting a control signal when pushed by the projection, and a planar light-emitter including a water-resistant illuminator which emits a light on receipt of power and which is in the form of a film, a transparent electrode adhered to a first surface of the planar light-emitter, and an electrode adhered to a second surface of the planar light-emitter. The water-resistant illuminator is formed with a hole through which the projection makes contact with the switch.
Japanese Unexamined Patent Publication No. 11-297161 has suggested a key structure used for a cellular phone, including a substrate, a base positioned above the substrate, a film formed on the base and having a plurality of pairs of fixed contacts, movable contacts covering the fixed contacts, key tops through which the movable contacts, and a light-emitting device which illuminates the key tops. The light-emitting device is positioned on the substrate, but below the base such that a light emitted from the light-emitting device passes through the base and the film.
The above-mentioned problem remain unsolved even in the above-mentioned Publications.
SUMMARY OF THE INVENTION
In view of the above-mentioned problems in the conventional light diffusion units, it is an object of the present invention to provide a light diffusion unit in which only a thickness of a light guide is increased without an increase in the number of a light source and further without an increase in a thickness of a portable electronic communication terminal including the light diffusion unit.
In one aspect of the present invention, there is provided a light diffusion unit including (a) a substrate formed with a first hole, (b) a case formed with a second hole
NEC Corporation
Sember Thomas M.
Young & Thompson
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