The Light Transmittance Testing of Tempered Glass Films-G-Tel

The Light Transmittance Testing of Tempered Glass Films

With the widespread use of devices like smartphones, tablets, and automobiles, tempered glass films have become essential accessories for protecting screens and enhancing display quality. Light transmittance, as a crucial performance indicator of tempered glass films, directly impacts the screen's display quality and visual experience. Therefore, light transmittance testing has become an essential part of the production and quality control process for tempered glass films.

This article will introduce the significance of light transmittance testing for tempered glass films, common testing methods, and its importance in practical applications.

1. Definition and Importance of Light Transmittance

Light transmittance, usually expressed as a percentage, refers to the ratio of light that passes through a material compared to the incident light. In simpler terms, the higher the transmittance, the clearer the glass film, allowing more light to pass through, which improves display quality.

The impact of light transmittance on tempered glass films is reflected in the following aspects:

• Display Quality: For electronic devices, the color accuracy, contrast, and clarity of the screen are directly related to light transmittance. A low transmittance protective film makes the screen darker, negatively affecting display quality and user experience.
• Visual Comfort: A high light transmittance film helps reduce screen reflections and glare, improving viewing comfort.
• Protection and Display Balance: While the primary function of a glass film is to protect the screen from scratches and impacts, high transmittance ensures that the film does not negatively affect the screen's natural colors and clarity, providing both protection and optimal display quality.

2. Common Methods for Testing Light Transmittance

Testing the light transmittance of tempered glass films typically requires the use of specialized instruments to ensure accurate results. The most common methods for testing light transmittance include:

(1) Spectrophotometer Testing

A spectrophotometer is a precision instrument commonly used for measuring the light transmittance of materials. It can precisely measure the transmittance across different light wavelengths, providing a comprehensive transmittance spectrum.

Working Principle: The spectrophotometer decomposes white light into different wavelengths and measures the amount of light that passes through the glass film for each wavelength. The results are typically displayed as a transmittance curve covering various light bands, from ultraviolet to visible light.

Steps:

1. Clean the sample thoroughly to remove dust and dirt.
2. Place the sample on the testing platform of the spectrophotometer.
3. Set the desired wavelength range (typically 300-800 nm) and start the test.
4. The instrument automatically records the transmitted light intensity and compares it with the incident light intensity, calculating the transmittance.

(2) Transmittance Meter

A transmittance meter is a convenient tool for quickly measuring the transmittance of tempered glass films. This device compares the intensity of the incident light and the transmitted light to calculate the transmittance.

Working Principle: A transmittance meter typically consists of a light source, a receiver, and a sample holder. When light is directed onto the glass film, the device measures the difference in light intensity before and after passing through the material, providing a transmittance reading.

Steps:

1. Secure the tempered glass film in place on the testing device.
2. Adjust the light source to ensure the light is incident perpendicular to the film.
3. Activate the instrument to record and display the transmittance value.

(3) Spectral Transmittance Measurement

This method is useful for analyzing how transmittance varies across different wavelengths and assessing its impact on display quality. By measuring the transmittance at specific wavelengths, this method provides a detailed analysis of the material’s optical properties.

Steps:

1. Use a high-precision spectrometer to measure the material’s transmittance.
2. Measure the transmittance at different wavelengths to create a complete transmittance profile.

3. Standards and Testing Specifications for Light Transmittance

The standards for light transmittance of tempered glass films usually depend on their specific applications. Different products may have different transmittance requirements. Here are some common standards:

• Smartphone and Tablet Screen Protectors:

  • For devices like smartphones and tablets, the light transmittance is typically required to be between 80% and 95%. A transmittance lower than this would result in a dimmer display, negatively affecting the user experience.
  • High-end products or professional display protectors may require the transmittance to be above 90% to ensure the screen’s color vibrancy and brightness are not compromised.

• Automotive Glass Films:

  • Automotive glass has stricter transmittance requirements. For example, in the United States, the ANSI Z26.1 standard mandates that the light transmittance of front windshields must be no less than 70%, ensuring a clear driving view, especially in low-light conditions like nighttime or rainy weather.

• Solar Glass Films:

  • In solar energy applications, the light transmittance requirement is very high, typically needing to be above 90% to maximize solar energy absorption and increase efficiency.

• Anti-Blue Light Films:

  • Anti-blue light films usually have a transmittance requirement of at least 85% to ensure eye protection while not significantly affecting the screen’s display quality.

International Standards:

• ISO 9050: This standard applies to measuring light transmittance in building glass, particularly for exterior glazing.
• ASTM E308: This standard from the American Society for Testing and Materials (ASTM) outlines methods for measuring light transmittance in optical materials.

4. The Importance of Light Transmittance for User Experience

Light transmittance is a critical factor that determines the user experience with tempered glass films, particularly in the following areas:

• Display Quality: High light transmittance ensures screen clarity, color accuracy, and contrast, without diminishing the brightness or clarity of the original display. Low transmittance leads to a darker, distorted screen that negatively affects viewing quality.
• Visual Comfort: A film with high light transmittance helps reduce glare and reflections, improving the viewing experience, especially in bright environments (like direct sunlight or outdoor use).
• Balance Between Protection and Functionality: In addition to providing screen protection, a tempered glass film should maintain the screen’s original display quality. High transmittance films provide the best balance between protection and display performance.

5. Conclusion

Light transmittance is one of the most important performance indicators for tempered glass films, directly impacting display quality, user experience, and the effectiveness of screen protection. By using professional testing instruments such as spectrophotometers and transmittance meters, accurate light transmittance measurements can be obtained to ensure that the product meets industry standards and user needs. For different applications (such as smartphones, automotive glass, solar panels, etc.), the required transmittance standards may vary, and manufacturers need to adjust and optimize their products accordingly.

Key Factors for Improving Light Transmittance:

• Using high-quality materials to ensure the film’s transparency and optical performance.
• Optimizing production processes to reduce surface inconsistencies and improve overall transmittance.
• Meeting industry standards to ensure the product meets the specific transmittance requirements for each application.

Testing the light transmittance of tempered glass films is a crucial step in ensuring product quality and customer satisfaction. Whether it's for consumer electronics, automotive applications, or renewable energy systems, maintaining high transmittance ensures both protective performance and optimal display clarity.