The touchscreen technology of all in one computers mainly relies on touch screens, and the working principle of touch screens is based on different types of sensing technology. Here are several common touchscreen technologies and how they work:

1. Resistive Touchscreen:

- Resistive touchscreens are made of multiple layers, with a soft, transparent conductive layer (usually polyester) on the top and a glass or plastic substrate coated with a hard conductive layer underneath. There is a tiny gap between the two layers.

- When the screen is touched, the top layer presses down to contact the lower layer, forming a circuit closure, and the touch position is determined by detecting the position change of this contact point.

2. Capacitive Touchscreen:

- Capacitive touchscreens use the human body as a conductor of the capacitor. The surface of the screen is covered with a layer of conductive material, such as indium tin oxide (ITO), which can store charge.

- When a finger touches the screen, it absorbs part of the charge, causing the electric field to change. The built-in controller can detect this change and calculate the exact location of the touch.

- This type of screen supports multi-touch, allowing users to operate with multiple fingers at the same time.

3. Surface Acoustic Wave (SAW) Touchscreens:

- SAW touchscreens use ultrasonic waves to propagate across the surface of the screen. When a finger or other object touches the screen, some of the energy is absorbed, affecting the signal.

- The controller determines the touch location by measuring changes in these signals. This type of screen generally provides high clarity and accuracy, but is sensitive to any physical contact.

4. Infrared (IR) Touchscreens:

- IR touchscreens have LED transmitters and photodiode receivers installed around the display's bezel, which form an invisible grid of infrared light.

- When a finger or other opaque object blocks the light, the receiver cannot receive the corresponding infrared signal, and the system uses this to determine the touch location.

5. Optical Imaging Touchscreens:

- Optical imaging technology uses cameras to capture images of touch points on the screen. Cameras are installed around the screen to detect the presence and movement of fingers or styluses.

- This method can achieve very large touchscreen sizes with good durability and accuracy.

6. Acoustic Pulse Recognition (APR) touch screen:

- APR touch screens rely on sound waves to work. When the screen is touched, the sound generated will propagate in a specific way on the screen.

- Built-in sensors can receive these sound waves and calculate the touch position based on the arrival time difference.

Most modern all in one computers use capacitive touch screens because they provide a better user experience, including higher sensitivity, clearer pictures, and support for gesture control. As technology develops, the response speed, accuracy and durability of touch screens are also constantly improving, providing users with a smoother and more natural operation experience.