Brushless vibration motor

Details Brushless vibration motor Brushless vibration motor

2003-06-24

2004-12-28

Le, Dang (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

Reexamination Certificate

active

06836039

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application claims to benefit of Korean Patent Application No. 2002-12004, filed Month day, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brushless vibration motor generating a receiving or alarm signal in a mobile telecommunication unit, such as a wireless phone, and more particularly, to a brushless vibration motor being capable of improving durability, vibration characteristics, a load reduction, and rotation characteristics using an improved shaft structure and a rotor assembling structure.
2. Description of the Related Art
According to a rapid development of digital technology, various types of wire or wireless telecommunication machines have been developed and widely used. Developments of wire or wireless telecommunication technologies provides machines facilitates transmission of huge amount of various information data in a very short period of time, thereby enabling the users to transmit and receive desirable information data regardless of a location and time. A wide and rapid transmission flow of the information data forms a global town with a development of transportation.
One of the wireless telecommunication machines is a personal mobile telecommunication terminal, such as a cellular phone or a personal communication system PCS. The cellular phone is one of digital or analog short wave transmission types connecting a mobile telephone to a transmitter/receiver of which service area is called a cell.
Although the PCS is the same wireless service system as the cellular phone, the PCS provides mobility for personal use. The PCS is also called to a digital cellular phone for a mobile user and requires a great number of antennas covering various service areas. A closest antenna is supposed to be used to receive/transmit a signal from/to the PCS and transmit the signal to a wireless network station.
A cellular system operates in a frequency band ranging 824-849 MHz, and the PCS operates in a frequency band ranging 1850-1990 MHz. Since the PCS has a data transmission rate of 8-13 Kbps, a high speed data transmission is almost impossible. According to the development of digital telecommunication technologies, a more high speed transmission of data packet, video, multimedia enables a personal telecommunication to receive various services, such as a voice telephone, telex, wireless calling, electronic mail, etc.
In accordance with the development of the telecommunication technologies and parts, integration and miniaturization of electronic products, and multifunctional system, telecommunication terminals employs various types of equipment, such as a digital camera transmitting a digital image, an audio unit generating a receiving call with a high quality and a multiple channel, a display device displaying an image using a high resolution, a wide viewing angle, and a high response time.
An alarm is realized in a bell sound mode or a vibration mode to generate the calling signal of a received call, a received electronic mail, and a predetermining time. Bell sound of the bell sound mode is stored in the mobile telecommunication terminal in a manufacturing process or downloaded through Internet connected to the telecommunication terminal. The vibration mode is performed using a vibration motor having a rotor. The vibration motor currently used in a mobile telecommunication terminal is one of a brush vibration motor and a brushless vibration motor or one of a bar type vibration motor and a coin type vibration motor.
A conventional brush vibration motor having a coil type used in the mobile telecommunication terminal is shown in
FIG. 1. A
structure and an operation of the conventional brush vibration motor is described hereinafter, and then a conventional brushless vibration motor removing problems occurring in the conventional brush vibration motor will be described later.
FIG. 1
is a cross-sectional view of a brush-type vibration motor,
FIG. 2
is an exploded view of the brush-type vibration motor shown in
FIG. 1
, and
FIGS. 3A and 3B
are a plan view showing an arrangement of a coil and a commutator contacting a brush of the brush-type vibration motor shown in
FIGS. 1 and 2
.
As shown in
FIGS. 1 and 2
, a bracket
1
having a fixed plate (base plate) is formed with a burring element (not indicated with a reference numeral) extended upward from a center portion of the bracket
1
, and a shaft
5
includes a first end inserted into the burring in a vertical direction and fixedly coupled to the bracket
1
using a washer. A flexible printed circuit board (FPCB)
2
is mounted in an upper surface of the bracket
1
, and a predetermined circuit and a terminal unit are formed on the FPCB
2
.
A magnet
3
having a ring—shape is mounted on an upper surface of the FPCB
2
of the bracket
1
around a shaft
5
. The magnet
3
includes a plurality of magnet poles having one of N and S polarities. A brush
4
is connected to the FPCB
2
at one end and contacts one of segments of a commutator of a rotor
10
at the other end which is disposed above an upper surface of the magnet
3
.
The rotor
10
is rotatably disposed around the shaft
5
. The rotor
10
includes a counterweight
13
generating eccentricity for vibration of the motor, coils
12
through which alternative current flows, a bearing reducing friction between the shaft
5
and the rotor
11
, and a resin formed in a single body insertion injected method as an insulation material.
The counterweight
13
is mounted on a portion of the rotor
10
to generate the eccentricity and the coils
12
is disposed on the rotor
10
in a circular direction of the shaft
5
to generate a magnetic field upon receipt of the alternative current from the commutator. The rotor
10
includes the bearing inserted around the shaft
5
and is formed in a monolithic body by filling the space with the resin as the insulation material.
A shape of the rotor
10
varies according to a desirable vibration type in the vibration motor. The number of the coils
12
is also variable as well as an arrangement of the coils
12
according to a motor driving method. If the arrangement of the coils
12
and the magnetic poles of the magnet
3
are changed, a rotation electromagnetic force occurring due to the magnetic field generated between the coils
12
and the magnet
3
is changed, and accordingly, a torque and a rotation speed of the rotor
10
are changed. In a three phase driving methods. The number of the coils is a multiple of 3.
A printed circuit board
14
is mounted on a bottom surface of the rotor
10
, and the commutator having the segments is mounted on the printed circuit board
14
to supply the current to the coils
12
. When the rotor
10
rotates, respective segments of the commutator contact the brush
4
according to a rotation position of the commutator corresponding to the brush.
A cover
20
having a cap shape and an inner portion fixedly supporting a distal end of the shaft
5
is connected to a circumference of the bracket
1
to enclose the rotor
10
and the magnet
3
.
An operation of the brush vibration motor having the above structure is explained hereinafter. The current flows through the brush
4
and the coils through the segments of the commutator contacting the brush
4
. The coils
12
are excited upon receipt of the current, and the magnetic field is generated in the coils
12
through which the current flows according to Fleming's rule. The rotation electromagnetic force is generated when the magnetic force of the coils
12
is offset with another magnetic field generated from the magnet
3
having the magnetic poles.
The rotor
10
starts to rotate in accordance with the rotation electromagnetic force generated between the coils
12
and the magnet
3
. When the brush
4
contacts different segments of the commutator, the coils
12
are turned on an off, and accordingly a change of the rotation electromagnetic force

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