Patent Application
20110074228
This application claims the benefit of Korean Patent Application No. 10-2009-0092427, filed with the Korean Intellectual Property Office on Sep. 29, 2009, the disclosure of which is incorporated herein by reference in its entirety.
1. Technical Field
The present invention is related to a vibration motor.
2. Description of the Related Art
A vibration motor is a part that converts electrical energy into mechanical vibrations by using the principle of generating electromagnetic forces, and is commonly installed in a mobile phone to generate a soundless vibrating alert. With the rapid expansion of mobile phone markets and increased functionalities added to the mobile phone, mobile phone parts are increasingly required to be smaller and better. As a result, there has been an increased demand for the development of a new structure of vibration motor that can overcome the shortcomings of conventional vibration motors and effectively improve the quality.
As mobile phones having a bigger LCD screen have become popular for the past few years, there have been an increasing number of mobile phones adopting a touch-screen method, by which vibration is generated when the screen is touched. Touch-screens particularly require that the vibration motor has a greater durability due to a greater frequency of generating vibration in response to the touch compared to the vibration bell for incoming calls and that the vibration has a faster response to the touch made on the touch screen, in order to provide a user a greater satisfaction from sensing the vibration when touching the touch screen.
Commonly used to overcome the drawbacks of shorter life time and slower responsiveness in the vibrating functionality of touchscreen phones is a linear vibration motor, which does not use the principle of rotating of a motor but uses an electromagnetic force having a predetermined resonant frequency to generate vibrations by use of a spring installed in the vibration motor and a mass coupled to the spring. Here, the electromagnetic force is generated through an interactive reaction between a magnet, which is placed on the moving mass, and a direct or alternating current having a particular frequency flowing through a coil, which is placed on a stationary part.
In the conventional vibration motor, however, it is difficult to generate resonance because a frequency band in which the resonance occurs is very narrow. In other words, the linear vibration motor has a weaker vibration force if there is a difference between the resonant frequency (fn) and an input frequency.
The present invention provides a vibration motor that can increase the amplitude of vibrations in a wider frequency band.
An aspect of the present invention provides a linear vibrator that includes a cylinder-shaped coil unit, a vibrator, which is inserted into the coil unit and includes a magnet that forms an asymmetric magnetic field in a vibration direction, and an elastic body, which elastically supports the vibrator.
The magnet can include a core and a pair of magnetic members, in which the pair of magnetic members are coupled to either end of the core and have different magnetic forces from each other.
The magnet can include a core and a pair of magnetic members, in which the pair of magnetic members are coupled to either end of the core and have different diameters from each other.
The magnet can include a core and a pair of magnetic members, in which the pair of magnetic members are coupled to either end of the core and have different lengths from each other.
The core of the magnet can be disposed eccentrically in the coil unit.
The vibrator can further include a weight, which is coupled to the magnet.
The vibration motor can further include a base having a bobbin formed thereon, and the coil unit can be coupled to the bobbin.
The vibration motor can further include a base having a pair of supporting parts formed thereon, in which the pair of supporting parts face each other. Here, a pair of the elastic bodies can be respectively interposed between the vibrator and the pair of supporting parts.
Another aspect of the present invention provides a vibration motor that includes a cylinder-shaped coil unit, a vibrator, which includes a magnet inserted into the coil unit, and a pair of elastic bodies, in which each elastic body elastically supports either end of the vibrator and has a different elastic characteristic.
The pair of elastic bodies can have different moduli of elasticity from each other.
The pair of elastic bodies can have different shapes from each other.
The pair of elastic bodies can have different displacements of vibration from each other.
The vibration motor can further include a base accommodating the vibrator. Here, the elastic body can be a leaf spring including a frame and a plurality of elastic members, in which the frame is coupled to the base or the vibrator and the plurality of elastic members are extended from an inner side of the frame.
The vibrator can further include a weight, which is coupled to the magnet.
The vibration motor can further include a base having a pair of supporting parts formed thereon, in which the pair of supporting parts face each other. Here, the pair of elastic bodies can be respectively interposed between the vibrator and the pair of supporting parts.
The vibration motor can further include a base having a bobbin formed thereon, and the coil unit can be coupled to the bobbin.
Additional aspects and advantages of the present invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
The features and advantages of this invention will become apparent through the below drawings and description.
A vibration motor in accordance with an embodiment of the present invention includes a coil unit 130, a vibrator, which has a magnet 200, and an elastic body 400. The vibration motor can also include a base 100, and the vibrator can also include a weight 500.
The base 100, in which the components of the vibration motor are housed, has a space that supports the components of the vibration motor. In this embodiment, a bobbin 110 is disposed at the center of the base 100, and a pair of supporting parts 102 facing each other are formed on either end of the base 100.
Specifically, the bobbin 110 is a part that can support the coil unit 130 and can have a cylindrical shape having a hollow part 112 formed therein. Also, the pair of supporting parts 102 can be formed in the shape of a pair of partition walls facing each other and formed on either end of the base 100. Meanwhile, a case 600 covers the base 100 and forms the exterior of the vibration motor.
The coil unit 130 generates an electromagnetic force that is needed to generate vibrations and has a cylindrical shape having a hollow part formed therein with a coil being wound on the cylindrical shape. By inserting the bobbin 110 into the hollow part of the coil unit 130, the coil unit 130 can be installed on the base 102.
A substrate 120 is a part that provides electrical connection to the coil unit 130. A circuit pattern can be formed on one surface of the substrate 120. The substrate 120 is installed on the base 102, and the bobbin 110 can be exposed toward the upper side of the substrate 120 through an opening formed at the center of the substrate 120.
The vibrator is a part that reciprocates in the base 100 and can be vibrated by the electromagnetic force of the coil unit 130. The vibrator of this embodiment includes a magnet 200 and a weight 500.
The magnet 200 is a part that receives force from the electromagnetic force of the coil unit 130, and the magnet 200 of the present embodiment forms an asymmetric magnetic field in the direction of vibration.
The magnet 200 of this embodiment has a cylindrical shape extended lengthwise. By being inserted into the hollow part of the bobbin 110, the magnet 200 can move horizontally in the hollow part of the bobbin 110.
Particularly, the magnet 200 of the present embodiment forms an asymmetric magnetic field in the direction of vibration. That is, magnetic fields having different shapes or different sizes are formed on either lengthwise side of the magnet 200.
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The weight 500 is a rectangular cuboid generally surrounding the yoke 300. The weight 500 is installed outside the magnet 200 and the yoke 300 and can generate strong vibrations through repetitive horizontal movement with the magnet 200.
The elastic body 400 is a part that elastically supports the vibrator in such a way that the vibrator can resonate. For this, the elastic body 400 is interposed between the base 100 and the vibrator.
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Hereinafter, a vibration motor in accordance with another embodiment of the present invention will be described.
Compared to the previously described embodiment of the present invention, a vibration motor in accordance with the present embodiment of the present invention is different in that the pair of elastic members 410 and 420, each of which is interposed between the base 100 and either end of the vibrator, have different elastic characteristics from each other. Here, the magnet 200 can be formed asymmetrically, like the previously described embodiment of the present invention, or formed symmetrically, like the magnet in accordance with the related art. Thus, identical description of the previously described embodiment or the related art will be omitted, and the pair of elastic members 410 and 420 will be mainly described herein.
The elastic bodies 410 and 420 are parts that elastically support the vibrator in such a way that the vibrator can resonate. For this, the elastic bodies 410 and 420 are respectively interposed between the base 100 and either side of the vibrator. Particularly, the vibration motor of the present embodiment includes the pair of elastic members 410 and 420, which have different elastic characteristics from each other.
For this, the pair of elastic members 410 and 420 can have different elastic moduli from each other. Specifically, each elastic member can be made of a material having a different modulus of elasticity.
Also, the pair of elastic members 410 and 420 can have different shapes from each other. As a result, the pair of elastic members 410 and 420 can have different elastic forces from each other while they are deformed by a same displacement.
Furthermore, the pair of elastic members 410 and 420 can have different displacements of vibration from each other. By setting the initial displacement differently or setting the maximum displacement differently, the elastic members 410 and 420 can have different elastic characteristics from each other even though they are made of a same elastic material.
Therefore, an asymmetric elastic force is formed on both sides of the vibrator so that an elastic force received by the vibrator from the elastic members 410 and 420 can vary according to the moving direction of the vibrator. As a result, the elastic force can have a nonlinear characteristic, and thus a frequency bandwidth in which a resonance occurs can be expanded.
While the spirit of the present invention has been described in detail with reference to particular embodiments, the embodiments are for illustrative purposes only and shall not limit the present invention. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2009-0092427 | Sep 2009 | KR | national |
