Outdoor advertising displays/charging piles/industrial control computers outdoor high-brightness LCD screen heat dissipation solution

Whether it’s the 2000cd/m² ultra-high brightness screen of outdoor advertising displays, the 15.6-inch touchscreen of charging piles, or the embedded display module of industrial control all-in-one PCs, under conditions of high temperature, direct sunlight, humidity, dust, and long-term 24/7 operation, the heat dissipation capacity of the display module directly determines the product’s lifespan, availability, and failure rate. In the fields of outdoor equipment and industrial control, the heat dissipation design of LCD screens has always been one of the key factors affecting the overall reliability of the machine.

Many problems exposed in the later stages of engineering projects—including LCD blackening, backlight decay, driver board crashes, bonding layer bubbles, capacitive touch drift, and frequent motherboard restarts—are almost all related to heat dissipation design. Heat dissipation is not simply a matter of adding a heatsink or a fan to the module; it is a systematic engineering project encompassing structural design, thermal aisle planning, material selection, power control, drive strategy, and environmental adaptability.

Outdoor Advertising Displays: The Scenarios with the Most Stringent Heat Dissipation Requirements

The heat dissipation difficulty of outdoor advertising displays is the highest among all equipment types. On the one hand, it typically uses a large-size, high-brightness screen of 43–86 inches, with a brightness of 1500–3000 cd/m², resulting in extremely high backlight power consumption. On the other hand, its glass panel is constantly exposed to direct sunlight, and under intense summer heat, the screen surface temperature can easily reach 70–85℃. Ordinary LCD panels will blacken at around 65℃, therefore outdoor advertising displays must use anti-blackening LCDs and have a comprehensive cooling system.

1. Structural Challenges Caused by High Heat Flux Density of the Backlight The backlight system of the high-brightness screen is the largest heat source of the entire machine. Taking a 55-inch high-brightness screen as an example:
2. Standard brightness backlight power consumption: 20–30W
3. High brightness backlight power consumption: 45–60W
4. Ultra-high brightness can even reach: 80W and above. Backlight temperature is typically 25–45℃ higher than ambient temperature. If the heat dissipation design is insufficient, backlight temperature will accumulate rapidly, causing:
5. LED color temperature drift
6. Backlight driver board entering protection mode
7. Screen brightness decrease, screen flicker
8. Localized blackening of liquid crystal molecules due to heat.

Therefore, outdoor advertising machines must adopt large-area aluminum backplates, heat spreaders, heat pipes, and other heat-conducting structures from the initial design stage to quickly conduct the heat generated by the backlight to the metal casing.

2. The Necessity of a Dual-Airflow Heat Dissipation System Outdoor advertising machines often contain multiple heat sources: large-screen backlight, Android motherboard, power module, player motherboard, etc. If all heat sources share a single sealed cavity, heat will accumulate further. The most common and effective engineering approach is to use a “dual-channel structure”:
3. Front air duct: Dedicated to cooling the LCD screen.
4. Rear air duct: Used for electronic modules such as the motherboard and power supply.

The advantages of a dual-channel system include:

1. Preventing heat from the motherboard from being transferred to the LCD display area.
2. Allowing cool air to enter the back of the LCD, reducing backlight temperature.
3. Ensuring independent and stable heat dissipation for electronic modules.

Industrial-grade fans must be used within the air ducts, ensuring positive pressure exhaust to prevent dust from being drawn into the equipment.

3. Hot and Cold Air Separation Design
   After air enters the equipment, cool air should enter from the bottom and rise to the top. When the cool air’s temperature rises after passing the backlight and motherboard, it should be immediately exhausted from the top to avoid mixing with other cool air. Commonly used in engineering are:
4. Air guide ducts
5. Metal partitions
6. Extended air ducts
7. Layered structure

This avoids the problem of “hot air remaining inside the cavity” due to internal circulation.

4. Glass Thermal Management: Reducing Solar Radiation Ingress
   The front glass of outdoor advertising displays typically uses:
5. AR glass (anti-reflective)
6. AG glass (anti-glare)
7. Insulating glass structure
8. Infrared blocking film (IRCut)
   These structures not only improve readability under sunlight, but more importantly, they:
9. Reduce direct heat transfer to the LCD
10. Alleviate heat buildup in the backlight area
11. Prevent a rapid temperature rise under direct sunlight. A 3–5°C reduction in glass temperature can lower the LCD backlight temperature by more than 10°C, a crucial heat dissipation point often overlooked in outdoor advertising displays.

Charging Stations: Heat Dissipation Strategies for Small and Medium-Sized Equipment

The LCD screens in charging stations are typically 10.1–15.6 inches, with brightness between 800–1500 cd/m². Compared to digital signage machines, power consumption and heat generation are significantly reduced, but heat dissipation challenges include:

1. A more enclosed cavity
2. Compact equipment installation
3. Rain shelters often cover the screen, worsening heat dissipation conditions
4. The internal power module itself generates significant heat
5. The equipment typically faces south and is exposed to direct sunlight.
6. Screen and power supply must be installed in separate cavities. DC power modules can reach temperatures of 70–90℃ during prolonged operation. If the screen and power supply are placed in the same cavity, the screen backplate may consistently reach temperatures above 60℃, leading to LCD aging and blackening.

Engineering recommendations:

1. Add a heat insulation plate between the display area and high heat sources.
2. Independent heat dissipation for the two cavities.
3. Use a fully enclosed metal structure for the screen cavity to improve thermal conductivity.
4. Utilize a metal casing for natural heat dissipation. Charging pile casings are generally made of painted metal, which has good thermal conductivity. Engineering methods include:
5. Placing the LCD module backplate in contact with the metal casing.
6. Adding thermal pads to improve thermal conductivity.
7. Adding an aluminum plate to the inside to improve heat dissipation. Natural heat dissipation is particularly effective for medium-brightness screens. 3. Anti-blackening LCD is mandatory.

Due to concentrated sunlight, the front panel temperature of charging piles is typically 20–35°C higher than the ambient air temperature. Non-anti-blackening LCDs will fail around 65°C, while anti-blackening LCDs can withstand 95–105°C. Therefore, charging piles must use anti-blackening LCDs.

4. Heating film for ultra-low temperature areas.

Below -20°C, the LCD may freeze, causing slow response or even residual dark areas. Heating films are typically installed on the back of the LCD:

1. Temperature < -10°C: Automatic heating
2. Temperature > 0°C: Automatic shutdown

Ensuring normal operation even in winter.

Industrial PCs: Compact Structure but Varied Environmental Cooling Requirements

Industrial PCs are typically used inside equipment such as control cabinets, machinery, and industrial instruments. Their heat dissipation is relatively mild, but the high node density and small cavity still present challenges.

1. Separate cooling for the display and motherboard.
   Industrial motherboards (especially x86) have high temperatures, potentially reaching 65–85°C during long-term operation. If the backlight and LCD are housed in the same cavity, the backlight temperature will increase accordingly.

Best Practices:

• Install the display screen in the front cavity.
• Place the motherboard in the rear cavity.
• Use thermally conductive silicone strips to conduct heat to the metal casing.

1. Use a metal profile backplate to construct the heat dissipation structure.

• Many industrial PCs use aluminum profile casings because:
• Larger heat dissipation surface area
• Can be used as a structural component
• Strong thermal conductivity
• High reliability
• This is the most common and stable heat dissipation method in the industrial control industry.

1. Semi-enclosed structures require fan assistance.

• Industrial PCs without fans are prone to internal temperature concentration and require:
• Industrial-grade long-life fans
• Includes dust filters
• Reasonable airflow arrangement
• To passively or actively expel hot air.

Common Misconceptions and Failure Modes in Heat Dissipation Systems

• Many projects have encountered pitfalls in heat dissipation. This chapter lists common industry misconceptions.

Misconception 1: Adding fans without designing airflow.

• The function of a fan is to move air, not to create a cooling effect.
• Without airflow, air circulation is chaotic, and hot air cannot be effectively expelled.

Myth 2: Screen Too Close to Glass Creates Greenhouse Effect

An excessively thick air gap between the screen surface and the front glass creates a greenhouse effect, causing a rapid increase in surface temperature.

Recommendation: Use full lamination

Or reduce the air gap to 0.5–1.5mm

Myth 3: Screen and Power Supply in the Same Chamber

This is the most common cause of screen blackening.

Myth 4: Using Ordinary LCD Screens in Outdoor Devices

Non-anti-blackening LCDs cannot withstand prolonged exposure to sunlight.

Myth 5: Using Plastic Casings

Plastic has extremely poor thermal conductivity, causing all heat to accumulate inside the device.

Myth 6: Including a High-Brightness Screen in a Small Size

High-brightness screens consume a lot of power for backlighting and must be paired with:

A heat-dissipating metal backplate

A metal chamber

Airflow channels

Otherwise, the temperature will rise rapidly.

Recommended Final Strategies for Heat Dissipation Design

To ensure the long-term stable operation of outdoor advertising displays, charging piles, and industrial control computer LCD modules, a proper heat dissipation system must possess the following characteristics:

1. Higher brightness → greater backlight heat → more important heat dissipation
2. Outdoor sunlight exposure can push glass temperatures to 70–85℃, necessitating the use of anti-blackening LCDs.
3. Structural heat dissipation capacity takes precedence over electronic heat dissipation capacity.
4. Airflow is more important than fans; without airflow, fans are ineffective.
5. Full lamination significantly reduces the greenhouse effect and reflections.
6. Screen, power supply, and motherboard must implement zoned heat dissipation.
7. Heating films are needed in Northeast and Northwest China to cope with freezing temperatures.
8. Metal casings offer several times the heat dissipation capacity of plastic casings.
9. Backlight drivers must have a temperature compensation closed-loop mechanism.
10. Engineering design must always be based on worst-case environments, not laboratory conditions.

Heat dissipation is not just about temperature; it’s the core capability that determines whether the equipment can operate stably outdoors for 3–5 years.

The heat dissipation system for outdoor equipment is a system engineering project that must be designed holistically, considering structure, materials, heat dissipation channels, power supply, and display modules.

Hangzhou LEEHON Technology Co., Ltd., as a provider of LCD display driver solutions for the industrial field, has established in-depth cooperative relationships with many leading global LCD panel manufacturers such as BOE, TIANMA, IVO, AUO, Innolux, and Kyocera, and professionally supplies multi-brand, full-series industrial-grade LCD displays and customized solutions.