Electrical generator or motor structure – Dynamoelectric – Reciprocating
Reexamination Certificate
2000-03-22
2001-07-17
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Reciprocating
C310S017000, C310S025000, C318S114000
Reexamination Certificate
active
06262500
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a vibration generator.
Portable devices such as cellular telephones serving as the terminals of a mobile communications system sometimes contain a vibration generator within the portable device itself or within an accessory thereof to inform the user of an incoming call by silent vibration rather than by an audible ringing tone. The vibration produced by the generator is sensed by the human body to alert the user to the call.
Structurally speaking, the conventional vibration generator of this type includes a motor having a rotary shaft and a rotating body mounted on the shaft, wherein the center of gravity of the rotating body is located at a position different from that of the rotary shaft so that vibration is produced when the rotating body is rotated.
In a vibration generator having a structure of this kind, wobbling of the rotary shaft produced when the rotating body is rotated is utilized as the source of vibration. Consequently, the bearings of the rotary shaft of the motor are subjected to excessive force, a situation which detracts from the durability and reliability of the generator.
Taking note of the simple harmonic motion of a movable element that is fixed to the free end (movable end) of a spring, the Applicant has previously proposed a vibration generator (Japanese Patent Application Laid-Open No. 10-180186) which, as shown in
FIG. 8
, includes a generally C-shaped yoke
210
about which a coil
240
is wound, a leaf spring
220
having a lower end fixed to the approximate center of the yoke
210
, and a movable element
230
fixed to the upper, movable end of the leaf spring
220
.
The movable element
230
includes two permanent magnets
235
,
236
attached to respective ones of both sides of the yoke
234
. When a prescribed current is passed through the coil
240
, the movable element
230
undergoes simple harmonic motion so that the leaf spring
220
is deflected from side to side.
The proposed vibration generator, however, has a number of shortcomings.
Specifically, though the leaf spring
220
is used as a resilient member for supporting the movable element
230
, the leaf spring
220
is highly rigid. As a consequence, there is the danger that the leaf spring
220
will break with prolonged operation. Though the leaf spring
220
may be lengthened in order to prevent this, such an expedient makes it difficult to reduce the size of the vibration generator.
Another problem is that since the leaf spring
220
is fixed to the yoke
210
and movable element
230
by screws or rivets, the fixing operation is troublesome.
In addition, since two permanent magnets
235
,
236
are used, this is an obstacle to cost reduction.
Furthermore, the conventional vibration generator does not produce enough vibratory thrust. A vibration generator capable of producing stronger thrust is desired.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a vibration generator which is durable, provides strong thrust and is capable of being reduced in size, cost and weight.
According to the present invention, the foregoing object is attained by providing a vibration generator comprising: a movable element having a permanent magnet attached thereto; a stationary element having end faces which oppose, across prescribed gaps, respective ones of end faces of the movable element, the stationary element being excited by passing a current through an attached coil to form a magnetic path with the movable element; and a resilient support member having one end attached to the movable element and another end attached to the stationary element to thereby support the movable element for vibration in a direction in which the stationary element is magnetized by the coil. One pole face of the permanent magnet is made to oppose the stationary element and the stationary element is excited by the coil to make the end faces of the stationary element desired poles, whereby the movable element is caused to vibrate at a predetermined frequency in the direction in which the stationary element is magnetized by the coil.
Preferably, the one pole face of the permanent magnet is placed so as to oppose an outer peripheral side of the coil attached to the stationary element, thereby forming a magnetic path in which magnetic flux that emerges from the pole face of the permanent magnet passes through the outer peripheral side of the coil, penetrates the interior of the coil and then is guided in the direction in which the stationary element is magnetized by the coil.
Preferably, a high-permeability member is attached to the pole face of the permanent magnet on the side opposing the outer peripheral side of the coil, with the high-permeability member causing magnetic flux to collect at this pole face.
According to another aspect of the present invention, the foregoing object is attained by providing a vibration generator comprising: a movable element having a permanent magnet attached thereto; a stationary element having end faces which oppose, across prescribed gaps, respective ones of the end faces of the movable element, with the stationary element being excited by passing a current through an attached coil to form a magnetic path with the movable element; and a resilient support member having one end attached to the movable element and another end attached to the stationary element to thereby support the movable element for vibration in a direction in which the stationary element is magnetized by the coil. The movable element has arms, which extend toward the stationary element, provided on respective ones of both sides thereof, and the arms have respective inner side surfaces which constitute the end faces that oppose the respective end faces of the stationary element across the prescribed gaps.
Preferably, the resilient support member comprises a coil spring, and the movable element is supported by a pair of the resilient support members so as to vibrate in the direction in which the stationary element is magnetized by the coil.
Preferably, the stationary element comprises a fixed-element yoke to which the coil is attached, and a base made of synthetic resin to which the fixed-element yoke is secured.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
REFERENCES:
patent: 2111643 (1938-03-01), Salvatori
patent: 2997158 (1961-08-01), Moskowitz et al.
patent: 3312841 (1967-04-01), Makino
patent: 4945269 (1990-07-01), Kamm
patent: 5287027 (1994-02-01), Marshall et al.
patent: 5444313 (1995-08-01), Oudet
patent: 5559378 (1996-09-01), Oudet
patent: 5587615 (1996-12-01), Murray et al.
patent: 5909068 (1999-06-01), Wakiwaka et al.
Ezawa Mitsuharu
Fukuda Naoki
Ito Haruo
Wakiwaka Hiroyuki
Mullins Burton S.
Teikoku Tsushin Kogyo Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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