CHRONOMETRE ELECTRONIQUE A COMMUTATEUR D'AFFICHAGE ACTIONNE PAR LE COURANT DANS LA PEAU

ELECTRONIC TIMEPIECE WITH DISPLAY SWITCH OPERATED BY CURRENT FLOW THROUGH THE SKIN

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
The present invention provides an electronic time-
piece having a pair of electrodes mounted on the crystal of
a timepiece casing which control a switching circuit to
energize the display when the electrodes are connected by
contact with the skin of a wearer. The display may be
either a light emitting diode (LED) or a liquid display
crystal display (LCD).

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electronic timepiece having a display portion
operation of which is controlled by an electrical switch
comprising two spaced apart electrodes which are insulated
from each other but are adapted to be electrically connected
together on being simultaneously contacted by the body of a
user of the timepiece, both electrodes being mounted on the
exterior of the timepiece, the latter having a glass crystal
provided with at least one said electrode.
2. An electronic timepiece as claimed in claim 1 in
which the electrodes are formed of electrically conductive
material which has been evaporated onto the glass.
3. An electronic timepiece as claimed in claim 1 or 2
in which the electrodes are provided on the top of the
outer surface of the glass.
4. An electronic timepiece as claimed in claim 1 or 2
in which each electrode is mounted in a recess provided in
the glass.

Description

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BACKGROUND OF THE INVENTION
This invention relates to an electronic timepiece or
watch and, more particularly to a means to control the timepiece
display portion.
Conventional electronic tirnepieces are not provided with
an ON~OFF switch particularly and the electronic timepiece is
switched on when the battery is mounted and, where a liquid
crystal display is used, the display portion is constantly
operated.
Light emitting diode (LED) timepieces are provided with
a mechanical control switch to control the operation of the
display portion.
In the conventional construction, however, since a liquid
crystal timepiece is constantly displayed, the display operates
even when the timepiece is not being used, i.e. when the time-
piece is taken off or while sleeping at night.
Therefore electric power for operating the display is
required even at night when a display is not necessary.
Moreover, since the control switch of a LED display time-
piece is a mechanical push button type switch, operation and
mslfunction of the button can cause trouble. For instance, if
a user carries heavy loads with both hands, operating the button
is inconvenient.
OBJECT OF THE INVENTION
This invention aims to provide an improved method to
eliminate the above-mentioned difficulties and insufficiencies.
The object of the present invention is to provide a detecting
portion mounted on the surface of a timepiece crystal to control
a switching circuit which turns on the display of the timepiece.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an
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electronic timepiece wherein the construction and operation of
the display avoids the use of a mechanical switch. Rather, when
a part of the human body touches the timepiece glass surface, the
display is switched on instantly. Therefore it is advantageous
especially for LED display timepieces in which constant lighting
is impossible because of the electric power consumption.
Furthermore, for LCD timepieces, the display circuit can
be switched off at night time when the display is unnecessary,
thereby reducing the electric power consumption.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings,
Figure 1 is a vertical section showing an embodiment of
an electronic timepiece according to the present invention;
Figure 2 is a circuit diagram showing the switching
circuit of Figure l; and
Figure 3 is a vertical section showing another embodiment
of an electronic timepiece.
DETAILED EXPLANATION OF THE INVENTION
This invention relates to an electronic timepiece having
a switch to control the display portion.
Referring to Figure 1, reference numeral 1 is a trans-
parent watch cover or crystal of a watch case 2. On an upper
surface la of the glass crystal 1 are provided first and second
electrode portions 3, 4 which are electrically insulated and
physically separated from one another.
The electrode portions 3 and 4 are electrically conductive
materials such as gold, chrome, or the like and are adhered to
an upper portion la of the crystal 1. The electrode portion
may be ~ormed by vapor deposition for example.
Each of the electrode portions 3 and 4 is connected to
a circuit board 7 provided in the watch case 2 by lead wires 6

589
which pass through the crystal 1.
Figure 2 shows a circuit diagram of a switching circuit
according to the present invention. Reference numeral 8 is a
power source; reference numeral 9 is a detecting portion consist-
ing of the electrode portions 3 and 4 on the timepiece crystal 1.
The electrode portion 3 is connected to the plus side of the
power source 8, and the other electrode portion 4 is connected
to the base of a transistor 10. The emitter of the transistor
10 is connected to the other side of the battery 8.
The collector of the transistor 10 is connected to the
plus side of the power source 3 through a resistance 11 and also
connected to the timepiece display circuit 13 through an inverter
12.
Another embodiment of the electronic timepiece of the
present invention is shown in Figure 3, wherein: reference
numeral 1 is a timepiece crystal mounted on a timepiece case 2,
and on an upper surface la thereof are provided a first and
second electrode portions 3 and 4 as before.
The electrode portions 3 and 4 are provided in recessed
concave portions lb and lc whereby the upper surface of the
electrode portions 3 and 4 are coplanar with the upper surface
of the timepiece crystal 1.
Each of the elctrode portions 3 and 4 is connected with
a circuit board 7 provided in the timepiece case 2 by lead wires
6 which penetrate the timepiece crystal 1.
The operation of the electronic timepiece of the present
invention is as follows. When a finger is placed on each of the
electrodes 3 and 4, an electric current flows between the elec-
trodes and through the base of the transistor 10, the resistor
30 14 repre~onting the resistance of the hand. Then the tr~n8istor
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10 is switched on and the electric potential of the collector
of the transistor 10, which is the input signal of the inverter
12, is changed from a high level to a low level, and the output
signal of the inverter 12 is changed from a low level to a high
S level. The high level output of the inverter 12 turns on the
time display circuit 13, and the time is displayed.
Accordingly, if the display circuit of a liquid crystal
display (LCD) timepiece, for example, is designed to be switched
on when a first high level is continuously fed to the display
circuit and switched off when a second high level signal is fed
to the display circuit, the display of the timepiece can be
operated only when it is necessary.
Furthermore, if the display circuit of the light emitting
diode (LED) timepiece is designed to be switched on for a short
fixed period when a high level is fed as an input signal to the
display circuit, the display can be operated only when it is
necessary.