What are the classifications of resistive touch screens?

• By IDT

What are the classifications of resistive touch screens?

Resistive touch screens are mainly classified based on their internal structure, conductor materials, and working principles. The following is a detailed classification:

What are the classifications of resistive touch screens?

Resistive touch screens are mainly classified based on their internal structure, conductor materials, and working principles. The following is a detailed classification:

1.Classified by number of lines and structure (the most common classification)

This is the most core classification method, directly related to the durability, accuracy, and cost of the screen.

Four wire resistive screen 

Structure: Two layers of ITO (indium tin oxide) conductive film on top and bottom. There are four wires in total, with one lead on each side of the lower layer (glass substrate) in the X-axis direction and one lead on each side of the upper layer (flexible plastic film) in the Y-axis direction.

Working principle: Detecting coordinates through the principle of voltage division. First, apply voltage to the lower X-direction electrode, and the upper layer acts as a probe to detect the X-voltage and obtain the X-coordinate; Then switch and apply voltage to the upper Y-direction electrode, while the lower layer detects the Y-coordinate.

Features: 

Advantages: Simple structure and lowest cost. 

Disadvantages: The upper ITO film may experience linear wear due to frequent bending during use, resulting in a shorter lifespan (approximately 1 million touches). The anti-interference ability is relatively weak.

Applications: Early PDAs, low-cost industrial control devices, teaching equipment, etc.

Five wire resistive screen 

Structure: All leads are designed on the bottom glass substrate (4 electrode lines), while the upper flexible film only serves as a pure voltage probe (fifth line) without any electrode leads attached.

Working principle: Alternating voltage is applied to the four corners or edges of the bottom glass to form a uniform voltage field. When touched, the upper film conducts the voltage of the touch point to the controller and calculates the coordinates.

Features: 

Advantages: Extremely long lifespan (up to 35 million cycles or more), as the easily worn-out upper layer film no longer etches the ITO circuit and is only responsible for conduction. High positioning accuracy and good stability. 

Disadvantages: The cost is higher than that of the four wire type, and the structure is relatively complex. 

Application: In situations where high reliability and lifespan are required, such as ATM machines, industrial control systems, medical equipment, and high-end POS machines.

Six wire/seven wire/eight wire resistive screen 

Essence: It is an improved version of the five wire system, which compensates for voltage field unevenness caused by temperature, humidity changes, or long-term use by adding additional detection lines (induction lines) on the basis of the five wire system. 

Features: It further improves stability and accuracy, especially performing better in larger screen sizes or harsh environments. The highest cost. 

Application: Professional fields that require extremely high precision and stability, such as certain military, aviation, or special industrial equipment.

2.Classification by Sensor Material

Mainly guiding the material selection of the electrical layer, affecting transparency, durability, and cost.

ITO film on ITO glass 

The most common combination is a glass layer coated with ITO on the lower layer, and a flexible plastic film (such as PET) coated with ITO on the upper layer. High cost-effectiveness.

ITO film on ITO film 

Both upper and lower layers use flexible ITO film. The overall screen is thinner and more impact resistant (not fragile), but its surface hardness is lower and it is prone to scratches. Commonly used for mobile devices that require drop resistance. 

Metal coating/nanowires (such as silver nanowires)

A new material developed to solve the problems of high brittleness, high resistance, and increasing cost of ITO. Flexibility is better and more suitable for manufacturing bendable touch screens, which is a direction for the future development of resistive screens (and flexible electronics).

3.Classified by substrate type

The material of the outermost layer of the touch screen directly affects the user experience. 

Hard screen 

The outer layer is made of smooth hard plastic (such as acrylic) or glass. Good hand feel, wear-resistant, but may crack under strong impact.

Flexible screen (thin film screen) 

The outer layer is a soft plastic film. Resistant to impact and not easily broken, but the surface is prone to scratches and the hand feel is slightly poor.

4. Classified by surface treatment

Smooth screen: Smooth surface, strong reflection, high clarity.

Foggy screen (anti glare): The surface has been treated to exhibit diffuse reflection, which can effectively reduce ambient light reflection and is suitable for outdoor or strong light use, but the clarity is slightly reduced.

Summary comparison table

Core points:

The five wire type has become the mainstream and preferred technology for resistive touch screens due to its excellent lifespan and stability.

The four wire design still has applications in the price sensitive low-end market due to its low cost.

Multi line (six or more lines) is an enhanced five line screen designed for special needs.

Although the consumer electronics market (such as smartphones and tablets) is almost monopolized by capacitive touch screens, resistive screens still occupy an irreplaceable position in industrial control, medical equipment, outdoor equipment, self-service terminals and other fields due to their unique advantages such as being able to be operated with any object (gloves, stylus), resisting liquid interference (can also be used with water/oil on the surface), and controllable cost.

Four wire resistive touch screen:https://www.auo-lcd.com/products/touch/amt/