Linear Resonant Actuator (LRA) | Baolong Electronic Group
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Linear Resonant Actuator (LRA)

  What Is A Linear Resonant Actuator

Linear Resonant Actuator (Also call it Linear Vibration Actuator) is a very particular vibration motor compare to Eccentric Rotating Mass motor that provides not only faster response time and long lifetime but also stronger vibration. Due to its excellent performance, it has been more and more popular in the field of communication and wearables.

A linear Resonant Actuator is a spring + mass system. The mass moves linearly, up and down in the picture in the right, come into being the required haptic feedback. The linear Resonant Actuator must be driven at a narrow band(+-2 HZ) around the resonant frequency because of the spring constant. And different from a DC vibration motor, LRAs require an AC driving signal that can move the actuator up and down. If driven properly, they could be highly efficient and offer excellent acceleration.

linear resonant actuator diagram - Linear Resonant Actuator (LRA)
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  Linear Resonant Actuator In Baolong

Currently, Baolong focuses on the 0832 type LRA. This type Linear Vibration Actuator is also the most widely used linear motor at present. Imagine that a motor with only a diameter of 8mm and thickness of 3.2mm can bring more than 1G vibration. That’s why this motor is so popular now. If you want to buy linear vibrator, pls contact us.

You can click on the picture below for the details of the motors. We detailed the specifications, pictures, datasheet and so on for each motor. If you have any question or can’t find a suitable motor you can contact our engineer freely. All your emails will be handled in 24 hours.

BLM0832 FP74 1S U - Linear Resonant Actuator (LRA)

Our BLM0832-FP74-1S-U coin linear resonant actuator vibrates in the Z-Axis at 235 Hz. Rather than wire leads, it makes usage of a flexible printed circuit (FPC). PCB mounted pogo pins are suggested to get hold of the contacts pads on the FPC. Its current features make it a fantastic choice for wearable devices with limited electric battery capability. It draws only 19 ma @ 0.6 V while producing a vibration G-force of 0.55.

P2 Linear Resonant Actuators BLM0832 FP78 U - Linear Resonant Actuator (LRA)

Our BLM0832-FP78-U coin linear resonant actuator vibrates in the Z-Axis at 235 Hz. Compare to BLM0832-FP74-1S-U; this motor has the same performance parameters but different FPC. We highly recommend you to use this motor in the phone or wearable devices.

  Linear Resonant Actuator Drivers

In comparison with the typical Eccentric Rotating Mass motors, LRA’s are more expensive and must be drived by an AC signal. Of course, you can drive it by debugging PWM, but in order to achieve the best motor performance, we highly recommend that you use an external IC to drive it.Many companies make IC drivers for Linear Resonant Actuator supplying the right drive signals and include a library of haptic results you can choose. TI is definitely one particular company which makes LRA drivers IC. If you want to know more about TI IC, you can click on the link below.

 

Eight things to consider when choosing haptic feedback – part 1

Eight things to consider when choosing haptic feedback – part 2

drv2605 - Linear Resonant Actuator (LRA)
drv 2605 - Linear Resonant Actuator (LRA)
DRV2605 Use Guidance

  The Working Principle Of Linear Resonant Actuator

The coil is powered by AC and remains stationary inside of the LRA. The Internal magnet has N/S polarity. Under the above conditions, the electrified coil generates the magnetic field to move the magnet to attract the repel so that that spring can drive the mass block up and down to generate force. The working principle appears like an audio speaker generating noise. In a speaker, air is funnelled with a cone as well as displaced at various regularities by turning an AC frequency and amplitude right into a vibrational frequency and also amplitude– inside, a speaker accomplishes this task by moving a magnetic mass with a fast-changing rotating present. Unlike a speaker, which can be driven at arbitrary frequencies, an LRA is useful in haptic applications within a details frequency array.

Linear vibraiton actuator - Linear Resonant Actuator (LRA)
linear actuator core tech 1 - Linear Resonant Actuator (LRA)

  Linear Vibration Actuator Production Process

From the above introduction, I’m sure you should have understood the working principle of the linear vibration actuator. In fact, if we summarize the principle in one sentence, it should be that the energized coil converts the magnetic pole when changing the current. Next, we will introduce you the production process of the linear vibration actuator.

 

We divided the structure of linear resonance actuator into three modules, namely the coil module (including the coil and PCB), the mover module (including the weight and spring), and the chassis module (including the upper case, the lower case, and the magnet). We connected each module by laser welding. Completed the above steps, a linear vibrator was completed. You can learn more details from the product flow chart below.

linear resonant actuator diagram - Linear Resonant Actuator (LRA)
LRA PROCESSING FLOW CHART

  The Application Of Linear Vibration Actuator

The most widely used areas of linear vibrators today are mobile phones as the haptic feedback speed plays a vital role in the smartphones in 21st. The current mobile phone has canceled the physical button. And people are accustomed to using the tactile feedback generated by the motor instead of the physical buttons. Compare to ERM motor, LRA has faster acceleration which can take better haptic feedback to customers. The video in the right shows a teardown of the iPhone 4S, which made use of a linear vibrator to provide haptic feedback. Due to the unparalleled performance of linear vibrators and excellent life, more and more mobile phone brands are now beginning using linear vibration actuators.