Why Piezoelectric Elements Are Ideal for Haptic Feedback in Electronics

What is Haptic Feedback?

The term “haptic” is derived from a Greek word that means to grasp or perceive. In modern use, haptics specifically pertain to the sense of touch. In various electronic applications it is also used to name the force and tactile feedback built into a device to enhance user interaction with that product or system.

Employing vibration, movement, and force produced by several different mechanical actuator technologies, haptic feedback can realistically simulate the physical features of an object, like pressure, weight, and texture. Haptic feedback adds the third sense of touch (beyond sight and hearing) to user and machine interaction. This serves to improve physical interaction with a digital interface through enhanced device inputs and the confirmation of user actions. It can even simulate the manipulation of objects in the virtual world.

Facilitating the user experience with haptic technology has led to rapid acceptance and growth in its use across consumer, industrial, commercial, and military markets, including products and systems in gaming, automotive, and healthcare settings.

What are Haptic Actuators?

Physical sensations in products are produced by haptic actuators, which are electromechanical devices that generate vibration, movement, or pressure. Several different technologies are used in haptic actuators to produce movement, these include:

• Piezoelectric actuation uses a piezoelectric element that deforms and vibrates when an electric field is applied. View Same Sky’s piezo elements product offering.
• Vibration motor actuation (or eccentric rotating mass) uses an unbalanced weight attached to a motor shaft to produce low-frequency vibration.
• Electro-active polymer actuation employs the deformation of polymer material in an electric field to produce vibration.
• Linear resonant actuation uses a magnet oscillating at a specific frequency due to an applied electromagnetic force to produce vibration.
• Voice coil actuation uses the movement of a coil in a magnetic field when a current is applied to produce various frequencies and vibrations.

Each of these technologies offers designers different characteristics in their vibration frequency, power consumption, or level of precision, making them suitable for many different product applications dependent on the desired level of haptic feedback.

What is the Piezoelectric Effect?

The piezoelectric effect is the ability of certain materials to produce an electrical charge when a mechanical stress is applied to them. This process is also reversible, meaning that the application of an electrical field to piezo materials will result in mechanical strain or deformation in those materials that results in vibration or movement.

How are Piezo Elements Used in Haptic Feedback Designs?

The reverse piezoelectric effect is employed in piezo elements that are used in haptic designs. Thanks to the piezoelectric effect, piezo elements can also be used as force sensors in a product or system, if necessary.

Some piezoelectric elements are constructed of two layers that are bonded together with opposite polarization. When a voltage is applied, one layer expands while the other contracts, causing the actuator to bend. This leads to the common name of “piezo benders” for piezo elements. This bending motion, as opposed to a linear one, is useful in applications that require precise and small-scale displacement.

Multilayer piezoelectric elements are constructed with multiple layers of piezo material, producing higher force and displacement at lower voltages compared to single-layer elements. This is valuable for applications that require larger movements at lower power, and that also have space for the larger device.

This deflection, or bending, of piezo elements is directly proportional to the control signal and can be held at a fixed position as well as made to vibrate. This independent control of position and amplitude can allow for detailed signals that can convey more information than with other actuator technologies.

What are the Benefits of Piezo Elements in Haptic Feedback Designs?

Piezoelectric elements used in haptic feedback applications leverage the piezo effect to deliver fast, strong, and sharp haptic feedback. The typical response time of piezo elements used in haptic applications is one millisecond or less, making them ideal for applications requiring high precision and quick feedback. They also operate at lower power levels than alternative technologies because they do not require movement of a large mass within the actuator. This lower power operation also means they can be used in battery-powered systems for remote operation or portability.

The compact, thin profile of piezoelectric elements can also allow a designer to use multiple piezo elements in a design to provide a stronger haptic response and more localized feedback to the user.

Piezo elements are widely configurable in frequency, amplitude, and waveform. Availability in various sizes, shapes, thicknesses, voltages, forces, capacitance ratings, and mounting techniques makes them useful in a broad range of applications. They can also be customized to fit specialized needs.

Piezo Element Design Considerations for Haptic Feedback Systems

Several factors need to be taken into consideration when designing a haptic feedback system using piezoelectric elements. これには、以下が含まれます。

• Determination of the mass that needs to be moved (vibrated) in order to match the force required in the actuator
• Deciding whether a single-layer or multilayer piezo element is required
• Understanding the size or volume of the space available in your design for the haptic system
• Determining the axis of movement you require from the piezo element
• Verifying the available power source in your product and the capacitive load of the element to determine the appropriate piezo driver
• Determining the frequency range or target you require
• Determining the operating temperature range for your product or system to match it with the appropriate piezo element

Common Haptic Feedback Applications for Piezo Elements

Piezo elements generate precise and rapid haptic feedback that is appropriate for many existing and emerging products and markets, including:

• Touch screens in computers, cars, medical and test equipment
• Vehicle system feedback in cars and other transportation equipment
• Smartphones
• 産業用制御
• Gaming controllers
• Smart home appliances
• Wearable electronics
• Virtual reality systems for training, education, or amusement
• Surgical simulation and remote medical procedures
• Physical rehabilitation feedback devices

概要

Designing and building useful and user-acceptable haptic feedback into a product or system requires careful consideration of actuator factors, like vibration strength, sensitivity, precision, form factor, and power consumption. Piezoelectric elements offer precise and efficient operation across a broad range of operating requirements, making them an ideal way to implement this rapidly growing technology. Same Sky’s piezo elements offer a wide range of sizes to match the requirements of many vibration detection or touch feedback needs.

主な取り組み

• Haptic feedback enhances user interaction in electronic devices by simulating touch sensations like vibration, pressure, and texture.
• Haptic actuators are electromechanical components that create physical sensations using technologies like piezoelectric, voice coil, and linear resonant actuation.
• Piezoelectric elements use the reverse piezoelectric effect to deliver precise, responsive, and low-power haptic signals in real time.
• Piezo elements and multilayer piezo elements offer different motion profiles, force outputs, and voltage requirements for varied design needs.
• Design flexibility is a key advantage of piezoelectric elements, with options in shape, size, force rating, frequency response, and mounting styles.
• Low power consumption and high responsiveness make piezo elements ideal for battery-powered and portable haptic feedback applications.
• Designers must consider mass displacement, axis of movement, available power, frequency range, and temperature conditions for optimal performance when utilizing piezo elements.
• Common haptic feedback applications include smartphones, automotive controls, medical devices, industrial systems, gaming, and virtual reality platforms.