Information
-
Patent Grant
-
6700251
-
Patent Number
6,700,251
-
Date Filed
Tuesday, October 29, 200221 years ago
-
Date Issued
Tuesday, March 2, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Dennison, Schultz, Dougherty & MacDonald
-
CPC
-
US Classifications
Field of Search
US
- 310 81
- 310 31
- 310 12
- 310 13
- 310 15
- 310 17
- 310 20
- 310 23
- 310 27
-
International Classifications
-
Abstract
A cup-shaped yoke is axially movably provided in a cylindrical frame, and a cylindrical permanent magnet is securely provided in the yoke. A coil bobbin is cantilevered in the frame and inserted in a space between the yoke and the permanent magnet, and a driving coil is mounted on the coil bobbin. The yoke is held by a pair of coil springs for resiliently holding the yoke in the frame.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a vibrating device having an axially driven movable member, and more particularly to a vibrating device mounted in a portable telephone for signaling a user by vibration of the movable member.
In recent years, there is popularized various portable instruments such as portable telephone, PDA (Personal Digital Assistant), wearable computing instruments and so forth. In these instruments, vibrating devices are mounted for informing signals, by vibration without producing sounds.
FIG. 6
is a perspective view showing a conventional vibration device disclosed in Japanese Patent Laid Open 7-107699. A direct current motor
131
has a rotating shaft
136
supported by a bearing
133
. There is formed an annular groove
135
on which an eccentric weight
134
is secured by a fixer
140
.
In such a motor, since a commutator and a brush assembly are provided, or manufacturing cost increases. It takes a time before the rotating speed approaches 7000˜8000 rpm. Therefore, the device is improper to a device which vibrates in accordance with a music signal. Furthermore, arcs generated between the commutator and brushes cause the quality and the life of the motor to reduce.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a vibrating device which may be manufactured at a low cost and has a high performance.
According to the present invention, there is provided a vibrating device comprising an axially elongated frame, a hollow yoke having an axially elongated shape and an opening at an end thereof, and axially movably provided in the frame, a cylindrical permanent magnet securely provided in the yoke, a coil bobbin cantilevered in the frame and having an end portion inserted in the yoke from the opening and in a space between the yoke and the permanent magnet, a driving coil mounted on the coil bobbin, at least one coil spring provided for resiliently holding the yoke in the frame.
The yoke has a hollow cylindrical form, and the yoke has a cup shape.
At least one weight is secured to a bottom of the yoke.
A plurality of guide projections are provided on an inside wall of the frame for movably supporting the yoke.
A pole piece made of magnetic material is secured to an end of the permanent magnet.
The device further comprises a plurality of axial grooves in each of which the guide projection is axially movably engaged.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1
is a sectional side view showing a first embodiment of the present invention;
FIG. 2
is a sectional view taken along a line II—II of
FIG. 1
;
FIG. 3
is a sectional view of a second embodiment of the present invention;
FIG. 4
is a sectional side view showing a third embodiment of the present invention;
FIG. 5
is driving circuit for driving the device;
FIG. 6
is a sectional side view showing a fourth embodiment of the present invention;
FIG. 7
is a sectional side view showing a fifth embodiment of the present invention; and
FIG. 8
is a perspective view showing a conventional vibration device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1
is a sectional side view showing a first embodiment of the present invention,
FIG. 2
is a sectional view taken along a line II—II of FIG.
1
.
The vibrating device
10
of the present invention comprises a cylindrical frame
11
made of a resin, a vibrating assembly
20
axially movably mounted in the frame
11
, and a magnetic driving device
19
mounted in the frame
11
at an end thereof.
The vibrating assembly
20
comprises a cup-shaped yoke
21
having an opening
21
a
at an end and a bottom
21
b
at the other end, a cylindrical permanent magnet
22
secured to the yoke
21
at the axis thereof, and a pair of weights
23
a
and
23
b
secured to the outside and inside of the bottom
21
b
of the yoke
21
. The yoke
21
is slidably supported by two rows and three projections
14
and
15
formed on the inside wall of the frame
11
, so that the vibrating assembly
20
can be smoothly vibrated.
The vibrating assembly
20
is resiliently held at a neutral position by a pair of coil springs
24
and
25
provided between both axial ends and the frame
11
.
The magnetic driving device
19
comprises a coil bobbin
13
cantilevered in the end of the frame
11
and a driving coil
12
provided on the coil bobbin
13
. The coil bobbin
13
is made of a metal pipe, on the peripheral surface of which is formed an insulation layer. The coil bobbin
13
is inserted in a space
26
between the yoke
21
and the permanent magnet
22
.
The primary resonance frequency of the vibrating assembly
20
is 100˜160 Hz, the vibration at which is properly transmitted to the user's body. An alternating signal having a basic frequency of the primary resonance frequency is applied to the driving coil
12
from terminals
35
and
36
, so that the vibrating assembly
20
is axially vibrated.
FIG. 5
is a driving circuit for driving the vibrating device.
In operation, when a low frequency signal of about 100 -300 Hz is applied to input terminal
48
of the driving circuit
50
, the transistors
51
and
54
are turned on at a high level of the input signal. Consequently, a current passes the driving coil
12
through the transistors
51
and
54
from the Vcc to GND. And the current passes through the transistor
53
, coil
12
and transistor
52
at a low level of the input signal. Thus, an alternating current of the low frequency corresponding to the input low frequency signal flows in the coil
12
. Consequently, the vibrating assembly
20
is axially vibrated.
Although two coil springs
24
and
25
are provided in the above described embodiment, only one coil spring may be used to urge the vibrating assembly
20
in a direction. In such a case, the vibrating assembly
20
is pressed against a cushion. In addition, although each of the frame
11
and the vibrating assembly has an annular sectional shape, other shapes such as a rectangular sectional shape may be used.
FIG. 3
is a sectional view of a second embodiment of the present invention. There is provided three axial guide ribs
41
in the inside wall of a frame
40
, and three axial guide grooves
31
in the peripheral wall of a yoke
31
, with each of which the guide rib
41
is slidably engaged. Thus, a vibrating assembly
30
is smoothly vibrated without pitching, rolling and yawing.
Referring to
FIG. 4
showing a third embodiment of the present invention, a cylindrical pole piece
28
made of magnetic material is secured to the end of the permanent magnet
22
. In the device, distribution of magnetic flux from the pole piece
28
expands in the radial direction of the driving coil
12
. Consequently, the number of magnetic flux crosses in the driving coil
12
largely increases, thereby increasing converting efficiency to vibrating energy.
In the above described embodiments, although the yoke
21
has a cup-shape and the permanent magnet
22
is cylindrical, a cup-shaped permanent magnet and a cylindrical yoke may be used.
Referring to
FIG. 6
showing the fourth embodiment, a center yoke
60
is secured to the bottom of the yoke
21
. A first permanent magnet
61
and a second permanent magnet
63
are secured to each other, interposing a pole piece
62
. Each of the first and second permanent magnets has the same polarity.
In the fifth embodiment shown in
FIG. 7
, an end center yoke
64
is further secured to the second permanent magnet
63
.
In accordance with the present invention, the vibrating device is simple in construction and hence can be manufactured at a low cost, and has high quality.
While the invention has been described in conjunction with preferred specific embodiment thereof, it will be understood that this description is intended to illustrate and not limit the scope of the invention, which is defined by the following claims.
Claims
- 1. A vibrating device comprising:an axially elongated frame; a hollow yoke having an axially elongated shape and an opening at an end thereof, and axially movably provided in the frame; at least one permanent magnet securely provided in the yoke; a coil bobbin cantilevered in the frame and having an end portion inserted in the yoke from the opening and in a space between the yoke and the permanent magnet; a driving coil mounted on the coil bobbin; and at least one spring provided for resiliently holding the yoke in the frame.
- 2. The device according to claim 1 wherein the yoke has a hollow cylindrical form, and the yoke has a cup shape.
- 3. The device according to claim 2 further comprising at least one weight secured to a bottom of the yoke.
- 4. The device according to claim 2 further comprising a plurality of guide projections provided on an inside wall of the frame for movably supporting the yoke.
- 5. The device according to claim 4 further comprising a plurality of axial grooves in each of which the guide projection is axially movably engaged.
- 6. The device according to claim 2 further comprising a pole piece made of magnetic material and secured to an end of the permanent magnet.
- 7. The device according to claim 2 further comprising a center yoke secured to a bottom of the yoke, the permanent magnet is secured to the end of the center yoke.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2001-341285 |
Nov 2001 |
JP |
|
2002-014894 |
Jan 2002 |
JP |
|
US Referenced Citations (6)