How to solve the problem of low brightness on an LCD screen?

Insufficient brightness on LCD screens is a very common pain point in industrial, medical, and outdoor equipment applications. Low brightness not only affects visibility but can also make the image completely unreadable in bright sunlight, rendering the equipment unusable.

I. Common Causes of Insufficient LCD Brightness
Brightness problems usually stem from the following core factors:

1. Low Backlight Brightness (Traditional Indoor Screens)
The backlight is the "light source" of the LCD.

Standard backlight brightness: 250–400 nits Outdoor or high-brightness scenarios require: 600–2000 nits or more
Insufficient backlight brightness is the most common cause.

2. Low Polarizer Transmittance
LCDs have two polarizers, one on top and one on the bottom. If the transmittance is low, it will directly affect the overall brightness.

3. Inefficient Optical Films (Diffuser/Prism Films)
High-quality optical films can improve light utilization efficiency; inferior films will cause a large amount of light energy to be "wasted."

4. Poor Full Lamination Process

If the screen uses a frame-mounted structure (with an air gap), the change in light refractive index is significant, leading to decreased brightness.

5. Unoptimized Display Driver Parameters

Some screens lack optimization in driver IC parameters and PWM dimming, resulting in lower brightness.

6. Environmental Factors Making Brightness Appear Lower

For example: Direct outdoor light, highly reflective glass, or the display area being obstructed by a cover plate. These are not necessarily due to inherently low screen brightness, but rather the user's subjective perception of difficulty seeing clearly.

II. How to Improve LCD Display Brightness? (6 Commonly Used Methods by Engineers)

The following solutions are commonly used brightness enhancement methods in the industry, each with its own advantages and disadvantages.

Option 1: Increase Backlight LED Brightness (Most Direct)

This is the most common and effective method:
Increase the number of LEDs
Increase LED current
Replace with higher brightness LED chips, such as using dual-core LEDs

✔ Advantages: Significant brightness increase, best effect, used for outdoor/high-brightness screens

✘ Disadvantages: Increased power consumption, higher heat generation, requires redesigning the backlight

Option 2: Replace with a High-Transmittance Polarizing Film
Polarizing films come in many grades, with transmittance ranging from 35% to 44%.

✔ Advantages: No increase in power consumption, clearer display

✘ Disadvantages: Requires re-application of polarizer, slightly higher cost

Solution 3: Use Optical Brightness Enhancement Film (BEF/DBEF) (Key Point)

● BEF (Brightness Enhancement Film)
Concentrates light through a prism structure
Increases brightness by 30%–60%

● DBEF (Dual Brightness Enhancement Film)
Recycles reflected polarized light
Significantly increases brightness (up to 70%–100%)
More suitable for high-brightness screens

✔ Advantages: No increase in power consumption, one of the most "economical" high-brightness solutions, immediate effect

✘ Disadvantages: Higher cost, sensitive to film material supply chain, high assembly requirements (direction/angle cannot be wrong)

Solution 4: Upgrade Optical Structure (Diffuser Film/Reflector)
Replacing with higher quality diffuser film & reflector can reduce light loss and improve light extraction efficiency.

✔ Advantages: Lower cost, better light uniformity

✘ Disadvantages: Limited improvement, requires adjustment of backlight stack-up

Solution 5: Use full lamination process (OCA/OCR)

If you are currently using frame-mount with air gaps, light loss will increase significantly.

Switch to full lamination:

✔ Advantages: Brightness increase of 5-10%, significantly increased contrast, easier to see in sunlight, reduced reflection

✘ Disadvantages: High process requirements, increased cost

Solution 6: Software optimization (drive parameters / Gamma / PWM)

Suitable for situations where brightness is "limited": Increase the brightness parameters of the driver IC, adjust the PWM duty cycle, optimize the Gamma curve

✔ Advantages: No increase in hardware cost, quick results

✘ Disadvantages: Limited improvement, cannot exceed hardware limits

III. What to do if outdoor display brightness is particularly low?

Outdoor environments face two major challenges: direct sunlight + reflection.

Recommended combination: Use a 1200–2000 nits high-brightness backlight, add a DBEF dual brightness enhancement film, use full lamination, and add AR, AG, and AF optical processing.

This will ensure the screen remains clearly visible outdoors.

IV. Summary
Insufficient brightness in LCD displays is not a simple problem, but rather the result of multiple factors including optics, structure, backlight, and film materials.

To truly improve brightness, common solutions are as follows:

✔ Replace with a high-brightness backlight (maximum improvement)

✔ Add a BEF/DBEF brightness enhancement film

✔ Replace with a high-transmittance polarizer

✔ Optimize the optical structure

✔ Full lamination to reduce reflection

✔ Optimize drive parameters