1. Technical Field
The present invention relates to a linear vibration device.
2. Description of the Related Art
A general linear vibration device is a part that converts electrical energy into mechanical vibration using a principle of generating electromagnetic force. The general linear vibration device is mounted in a mobile communication terminal, a portable terminal, or the like, so as to be used for notifying mute termination.
In addition, with the sudden expansion of radio communication and mobile phone markets, a demand for a multi-functional mobile communication terminal has been increased. The performance and technology of the linear vibration device has been also developed day by day so as to surprisingly improve disadvantages and quality of the existing products under the conditions that miniaturization and high quality of parts of the mobile communication terminal are demanded.
Further, a release of a mobile phone having a large LCD screen has been suddenly increased in recent years. To this end, a touch screen type that generates vibrations at the time of touch is adopted. Today, a demand of the touch screen type has been increased.
Meanwhile, performance specifically required in vibrations according to the touch of the touch screen is as follows. First, with the increase in use frequency as compared with the vibration generation at the time of receiving a call, operation lifespan needs to be increased. Second, a user can feel vibrations at the time of touch by increasing a response speed of vibrations according to a speed touching the screen.
A linear vibration device, which is a linear vibration device satisfying the above-mentioned characteristics, generates vibrations by being vibrated by electromagnetic force, while having a resonance frequency determined by a spring and a vibrator to be connected to the spring. Further, the electromagnetic force is generated by interaction with current having a predetermined frequency, which is applied to a magnet of the vibrator and a coil of a stator.
The linear vibration device configured as described above generates touch noise by colliding the vibrator with a case or a bracket while the vibrator moves vertically. To prevent the touch noise, in the linear vibration device, a ring-shaped band is made by applying MF or a damping material (rubber, poron, or the like) has been used.
However, in the case of using the MF, since the MF is made of liquid, the MF is sprayed to the periphery at the time of excessive impact and is out of an original position to weaken the damping function, thereby causing the noise at the time of the vibration operation. The damping material such as rubber, poron, or the like, occupies a predetermined volume and thus, is difficult to be disposed within a restricted space and has a degraded freedom in design.