Camera Control Button: iPhone 16's Revolutionary Interaction, or the Next 3D Touch?

Camera Control Button: iPhone 16's Revolutionary Interaction, or the Next 3D Touch?The implementation of the CameraControl button was explained in detail by iPhone's product manager during the launch event, taking a full 23 seconds. It's fair to say the complexity is quite impressive

Camera Control Button: iPhone 16's Revolutionary Interaction, or the Next 3D Touch?

The annual iPhone update is here again. While hot AI features are still out of reach for now and the design remains similar, it seems like smartphone form factors are reaching their limits. However, smartphone interaction still has room to evolve. Take the CameraControl button on the iPhone 16, for example. One button can control the shutter, zoom, mode switching, and more with a press, long press, or touch, potentially becoming the next generation of interaction in electronic devices.

The implementation of the CameraControl button was explained in detail by iPhone's product manager during the launch event, taking a full 23 seconds. It's fair to say the complexity is quite impressive. The button still uses a traditional press-and-release mechanism, unlike the rumors of a completely solid-state design. It also features a set of high-precision force sensors and haptic motors to simulate different pressing forces and touch feedback. The button surface is sapphire-coated with a capacitive touch sensor to recognize sliding gestures. It's worth mentioning that the official case has a sapphire glass panel with a conductive layer to transfer finger movements to the CameraControl button.

While the features are roughly in line with prior leaks, the implementation is somewhat disappointing. For a company that always strives for simplicity, Apple's solution is overly complex, and there should be a better way. Why mess with a perfectly good button? Traditional mechanical buttons, due to their intricate structure, are susceptible to damage or failure from environmental factors like dust and moisture. For example, the iconic silent switch on iPhones is easily clogged with dust, and many users have sought service due to this issue. Solid-state buttons, on the other hand, are immune to these problems. From a design perspective, solid-state buttons have fewer moving mechanical components, which not only increases production efficiency but also reduces the failure rate. Solid-state buttons rely on capacitive sensing or pressure sensing technology for operation, with no mechanical structure, making them more durable and waterproof. Additionally, solid-state buttons can help create a seamless body, improving the device's seal and achieving the ideal "black box" minimalist design.

Last year, there were rumors that iPhone 15 Pro would adopt solid-state buttons, but it ultimately didn't happen. Later, foreign media reported that Apple's plan, named "Bongo," was an electromagnetically driven haptic feedback device that could deliver more nuanced and realistic haptic feedback. This technology would allow users to experience physical button-like haptic feedback when pressing virtual buttons, enhancing the intuitiveness and satisfaction of interaction. However, due to technological and production challenges, iPhone 15 Pro missed out on this feature, and the iPhone 16's button is merely a compromise that fulfills the functionality of solid-state buttons.

From a functional perspective, solid-state buttons bring more operational dimensions to off-screen interactions. Users can interact with their devices via different actions such as tapping, pressing, long pressing, and sliding. This diverse range of operations not only improves efficiency but also enriches the user experience. In a 2023 public patent, Apple demonstrated the ability to achieve multiple operations on a single button with different pressing forces and slides. For instance, a light touch could activate a preview function, while a harder press might execute a confirmation action. A press and slide could even perform multiple consecutive operations. However, patents are just patents, and real-world applications are another story.

Solid-state button attempts by mobile phone manufacturers If we define solid-state buttons as "not movable," many phones have experimented with this concept. Google introduced the ActiveEdge feature on its Pixel series, allowing users to trigger specific functions like launching Google Assistant by squeezing the body. Although this design only supports one operation, it offers a new interaction method, reducing the reliance on traditional buttons.

Apple first introduced the solid-state Home button in iPhone 7, replacing the traditional mechanical button. This solid-state Home button utilizes the Taptic Engine to provide haptic feedback, simulating the click feel of a physical button. Among Android phones, the Meizu 15 adopted a similar design, offering a more durable and waterproof Home button experience. Huawei introduced the on-screen virtual buttons in the Mate 30 series, placing UI buttons on the curved screen edges to achieve diverse operations. This design not only enhances the screen's integrity but also provides more interaction methods, such as volume control and camera shutter. Some gaming phones, such as the ASUS ROG Phone series, embed ultrasonic touch shoulder buttons into the frame. These solid-state buttons can recognize pressing force, sliding, and other operations, providing gamers with a richer control experience. This design not only enhances the accuracy of gaming operations but also reduces wear and tear on mechanical buttons.

Functionally, ultrasonic touch buttons can fully achieve all the functions of the button on the iPhone 16. So why has Apple only added it now?

The key challenge of solid-state buttons: "feedback" We've mentioned Apple's persistence in achieving "feedback" for solid-state buttons in the previous two sections. They strive to make solid-state buttons feel like mechanical buttons. Why does solid-state feedback necessarily need to be tangible? The answer is simple: it's a button, and buttons should provide feedback. This is our intuition.

In the Design Psychology book series, the author believes good design should adhere to five principles: affordance, signifier, constraint, mapping, and feedback. Feedback, however, is precisely the pain point for solid-state buttons. Take a vertical elevator, for instance. When you press the floor button, it should light up. If none of the buttons light up, but the elevator still takes you to your desired floor, wouldn't you think it's broken? Another scenario: you press a button, and all the buttons light up, but the elevator still takes you to your desired floor. Would you still think it's broken? These two scenarios illustrate a lack of feedback and unclear feedback, respectively.

Traditional mechanical buttons, due to their inherent mechanical structure, provide natural feedback when pressed and released. The audible click, the vibration felt by your finger - these feedbacks clearly indicate whether the button has been pressed. However, solid-state buttons almost eliminate all mechanical structures, inherently lacking audio or tactile feedback. Therefore, feedback must be added artificially.

Let's take the Home button on the iPhone 7 as an example. While technically not pressable, the Haptic Engine simulates the feel and vibration of pressing, so much so that many users back then were unaware that the Home button was completely fixed. Perhaps many people think the iPhone 16's button is just a relocated version of the old Home button. However, they are fundamentally different.

To ensure the realism of the feedback, it should directly act on the pressing location. The Home button on the iPhone 7 feels so authentic because the massive Haptic Engine vibration motor is located directly beneath the button. For side buttons, if the existing Haptic Engine located at the bottom is used to simulate feedback, the distance and position difference will cause the vibration to be inaccurately transmitted to the corresponding button, distorting the feedback. This is similar to the ultrasonic touch shoulder buttons found on gaming phones today. When triggering the button, the phone provides a vibration feedback, but the feedback comes from the entire palm, not the fingertip.

How to solve this problem? Add another vibration motor to the side button? The electromagnetically driven haptic device mentioned in Apple's Bongo plan is essentially what we commonly call an X-axis linear motor. However, even with a smaller size, it contradicts the initial purpose of solid-state buttons. The essence of using solid-state buttons is to eliminate mechanical structures and achieve a more minimalist design. Adding another vibration motor would be counterproductive. Who would have thought that Apple would create a super-complex button with capacitive touch and vibration, leaving many confused.

Solid-state buttons and the cutting-edge research of "Piezo" Although iPhone 16 didn't implement solid-state buttons, it doesn't stop us from discussing the implementation pathways. In 2021, David Julius and Ardem Patapoutian won the Nobel Prize in Physiology or Medicine for their discovery of temperature and touch receptors. Professor Patapoutian, through his research on pressure-sensitive cells, discovered two mechanosensitive ion channels, Piezo1 and Piezo2, which respond to mechanical stimuli from the skin and internal organs.

The word "Piezo" comes from the Greek word "piezein," meaning "to press" or "to squeeze." In modern science, "piezo-" is often used to represent phenomena related to pressure, such as the piezoelectric effect. The piezoelectric effect refers to the phenomenon where certain crystals generate electric charges on their surface when subjected to external forces, or deform under the influence of an applied electric field. Since its discovery, this effect has been extensively researched and developed over a century, playing an increasingly important role in modern technology.

From a microscopic perspective, piezoelectric materials and Piezo1/Piezo2 ion channels share striking similarities, primarily in their response mechanisms to mechanical forces. Specifically, Piezo1 and Piezo2 channels are embedded in the cell membrane in a manner that allows them to sense changes in membrane tension. When membrane tension increases, the channel structure transitions from a bent state to a flattened state, leading to the opening of the central pore, enabling the passage of ions. This mechanism is similar to the principle of the piezoelectric effect, where mechanical stress induces changes in polarization, both involving structural changes triggered