Electronic apparatus

Details Electronic apparatus Electronic apparatus

1999-09-10

2001-07-24

Fleming, Fritz (Department: 2836)

Electrical transmission or interconnection systems

Plural load circuit systems

Control of current or power

C307S106000

Reexamination Certificate

active

06265789

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an electronic apparatus in which one of two devices charges the other in a non-contact fashion, and to an electronic apparatus in which a one-way or two-way data transmission is possible between two devices, and, more particularly, to an electronic apparatus including one device, operated from a rechargeable secondary battery, such as a motorized tooth brush, a motorized shaver, a cordless telephone, a portable telephone, a PHS (Personal Handy-phone System: a simplified portable telephone system), a mobile personal computer, a compact information device, an electronic watch or the like, and the other device for charging the first device in a non-contact fashion.
BACKGROUND ART
It is becoming an accepted practice that a compact portable electronic apparatus, such as a portable terminal or an electronic watch, is put into a charging device called a station for charging with a signal transmission performed on the portable electronic apparatus at the same time. If the charging and the signal transmission are performed through electrical contacts in such a system, the contacts are exposed and the apparatus is weak in terms of waterproofness. For this reason, the charging and the signal transmission are preferably performed in a non-contact fashion, through the electromagnetic coupling between coils respectively arranged in the station and the portable electronic apparatus.
If a high-frequency signal is applied to the coil on the station in such a system, an external magnetic field takes place, inducing a voltage in the coil on the portable electronic apparatus side. By rectifying the induced voltage through a diode or the like, a secondary battery arranged in the portable electronic apparatus can be charged in a non-contact fashion. Through the electromagnetic coupling between the two coils, a signal can be transmitted in a two-way communication in a non-contact fashion from the station to the portable electronic apparatus or from the portable electronic apparatus to the station.
In the coil on the station side and the coil on the portable electronic apparatus side, not only the electromagnetic coupling is required to be assured but also the efficiencies in the battery charging and signal transmission are required to be enhanced.
In the conventional art, the surfaces of coil winding of the two coils are in parallel with their centers in alignment with each other when the portable electronic apparatus is placed into the station.
Placing the two coils into alignment by simply seating the portable electronic apparatus into the station is difficult because the positions of the coils attached in the station and the portable electronic apparatus are required to be accurate. There is a need for an arrangement which is intrinsically less affected from a modest degree of displacement between the two coils.
An apparatus shown in
FIG. 17
, as another background art, is now discussed. The apparatus includes a rechargeable secondary battery and an electronic device having a charging unit for performing a charging operation in a non-contact fashion, and is disclosed in Japanese Unexamined Utility Model Publication No. 60-8636, for example.
Referring to
FIG. 17
, there are shown a stand
51
, a power plug
52
, a handle
53
of a tooth brush, a power cord
54
, a secondary battery
56
, primary coils L
1
, L
2
, a secondary coil L
3
, diodes D
1
, D
2
, a transistor Tr, capacitors C
1
, C
2
, and C
3
, and a resistor R
1
. The electronic apparatus here is a tooth brush, in which a charging unit is installed in the stand
51
, and a charged unit is installed in the handle
53
. The stand
51
includes a high-frequency oscillator (self-oscillation circuit) composed of the primary coils L
1
and L
2
of a transformer, the transistor Tr, the resistor R
1
, and the capacitors C
2
and C
3
, and emits outwardly an electromagnetic field from the high-frequency oscillator circuit.
The charged unit in the handle
53
of the tooth brush includes the secondary coil L
3
of the transformer which is electromagnetically coupled with the primary coils L
1
and L
2
in the charging unit to induce a voltage therein, and further includes the rectifying diode D
2
and the secondary battery (Ni-Cd battery)
56
.
A user picks up the motorized tooth brush from the stand
51
by gripping the handle
53
of the tooth brush to use it, and when it is not used, the tooth brush is stored in its upright position in the stand
51
.
Since the primary coils L
1
and L
2
in the charging unit are electromagnetically coupled with the secondary coil L
3
in the charged unit in the storage state of the brush, a voltage is induced in the secondary coil L
3
in the charged unit. The induced voltage charges the secondary battery
56
through the diode D
2
.
The electronic apparatus shown in
FIG. 17
suffers from the following problems.
Since the motorized tooth brush is typically exposed to water, the stand
51
and the handle
53
of the tooth brush are waterproof-structured with gaskets so that internal circuits are not wetted with water. To maintain the waterproof structure against the pressure of tap water from a faucet, the members of the tooth brush need to have a sufficient strength not to deform under the water pressure. The outer resin portion of the handle
53
of the tooth brush needs a minimum of thickness, and the resin portion forming the housing of the stand
51
needs a minimum of thickness. For this reason, the gap between the primary and the secondary coils is increased, and the degree of magnetic coupling weakens, substantially reducing the charging current to the secondary battery for charging. The quick charging of the secondary battery cannot be made in a short period of time. If the handle
53
of the tooth brush or the housing of the stand
51
is constructed of a metal having a high rigidity, such as stainless steel, the gap between the primary and secondary coils can be reduced. In this case, however, eddy currents take place in the electrically conductive metal material, weakening the electromagnetic coupling. As a result, the quick charging of the secondary battery cannot be performed in a short period of time.
DISCLOSURE OF THE INVENTION
The present invention has been developed in view of the above problem, and the major objectives of the present invention are as follows. A first object is to enable a quick charge of a secondary battery to be performed by improving the efficiency of a power transmission from a charging unit to a charged unit in a non-contact charge.
A second object of the present invention is to enable a high S/N ratio, highly reliable data transmission to be performed by improving the efficiency of a data transmission from a data transmitting unit to a data receiving unit in a non-contact data transmission device.
To achieve the first and second objects, an electronic apparatus of the present invention includes a first device and a second device, which perform a power transmission or a signal transmission through the electromagnetic coupling of coils which are arranged in mutually facing positions in the respective devices, wherein one of the inner diameter of a first coil arranged in the first device and the inner diameter of a second coil arranged in the second device is larger than the other of the inner diameter of the first coil and the inner diameter of the second coil by at least 1 mm.
In another arrangement of the present invention, an electronic apparatus includes a first device and a second device, which perform a power transmission or a signal transmission through the electromagnetic coupling of coils which are arranged in mutually facing positions in the respective devices, wherein each of the ratios of (the inner diameter)/(the outer diameter) of the first coil and the second coil is equal to or greater than 0.3, and equal to or smaller than 0.7, and wherein one of the inner diameter of the first coil arranged in the first device and the inner diameter of the second coil arranged in the second device is larger than the othe

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