Standard No.:	GB/T 25273-2025
English Name:	Films for liquid crystal display（LCD）―Method for measuring haze and light transmittance―Integrating sphere method
Chinese Name:	液晶显示器(LCD)用薄膜雾度和透光率测定方法积分球法
Professional Classification:	GB    National Standard
Source Content Issued by:	SAMR; SAC
Issued on:	2025-02-28
Implemented on:	2025-9-1
Status:	valid
Superseding:	GB/T 25273-2010 Films for liquid crystal display(LCD)—Determination of haze with integrating sphere
Target Language:	English
File Format:	PDF
Word Count:	5000 words
Translation Price(USD):	150.0
Delivery:	via email in 1~3 business day

GB/T 25273-2025 Films for liquid crystal display（LCD）―Method for measuring haze and light transmittance―Integrating sphere method English, Anglais, Englisch, Inglés, えいご This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered. ICS 71.080.99 CCS G 15 National Standard of the People's Republic of China GB/T 25273-2025 Replaces GB/T 25273-2010 Films for liquid crystal display (LCD) - Method for measuring haze and light transmittance - Integrating sphere method 液晶显示器（LCD）用薄膜 雾度和透光率测定方法 积分球法 (English Translation) Issue date: 2025-02-28 Implementation date: 2025-09-01 Issued by the State Administration for Market Regulation the Standardization Administration of the People's Republic of China Contents Foreword 1 Scope 2 Normative references 3 Terms and definitions 4 Theory 5 Instruments 6 Samples 7 Test methods 8 Operational steps 9 Test report Films for liquid crystal display (LCD) - Method for measuring haze and light transmittance - Integrating sphere method 1 Scope This document describes the method for measuring haze and light transmittance of films for liquid crystal displays (LCD) using the integrating sphere method. This document is applicable to the determination of haze and light transmittance of optical transparent films for liquid crystal displays (LCD), such as cellulose triacetate (TAC) film, polyvinyl alcohol (PVA) film, polyethylene terephthalate (PET) film, and polymethyl methacrylate (PMMA) film. 2 Normative references The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB 2918 Plastics - Standard atmospheres for conditioning and testing 3 Terms and definitions The following terms and definitions are applicable to this document. 3.1 haze ratio of scattered luminous flux deviating from incident light direction after passing through specimen to transmitted luminous flux Note 1: Expressed in percentage. Note 2: Usually only scattered luminous flux deviating more than 2.5° from the incident light direction is used for haze calculation. 3.2 light transmittance ratio of luminous flux transmitted through specimen to luminous flux incident on specimen Note 1: Expressed in percentage. [Source: GB/T 33376-2016, 2.4.111, modified] 4 Theory 4.1 Direct measurement using an integrating sphere haze meter. Schematic diagram for measuring haze and light transmittance, see Figure 1. 4.2 Light entering the integrating sphere is reflected, and its intensity is detected by a photoelectric detector. 4.3 Haze calculated by Formula (1): 4.4 Light transmittance calculated by Formula (2): 5 Instruments 5.1 Sampling safety The test instrument is an integrating sphere haze meter, which should meet the following requirements: a) Light source: Standard C illuminant or D65 illuminant; b) Condenser lens: Focuses beam on specimen, producing essentially unidirectional parallel light, with deviation from optical axis not exceeding 3°; c) Integrating sphere: Total port area not exceeding 4% of internal reflective surface area; internal reflective surface with uniform, high reflectance, and non-glossy in visible wavelength range; d) Photoelectric detector: Measurement accuracy ≤ 1%, detectable wavelength range 380 nm to 780 nm; e) Light trap: Capable of completely absorbing light when no specimen is present. 6 Samples Test specimen requirements as follows: a) Specimens shall be flat, uniform, free from visible defects such as bubbles, streaks, impurities; b) Specimen dimensions: (50 ± 5) mm × (50 ± 5) mm; c) Avoid direct hand contact with specimen surfaces during sampling and testing; d) Minimum of three parallel specimens for testing. 7 Test conditions Test conditions shall meet the following requirements: a) Prior to measurement, condition specimens for at least 2 hours under standard atmosphere (23 ± 2)°C and relative humidity (50 ± 5)% as specified in GB/T 2918; b) Dust-free environment; instrument protected from strong direct light; absence of strong magnetic fields, electric fields, strong air currents, and corrosive gases; c) Instrument workbench shall be stable and level; d) Specimen and instrument measurement surfaces free from contamination such as oil, dust. 8 Operational steps Procedure shall meet the following requirements: a) Connect power, switch on, and preheat instrument for over 30 minutes; b) Calibrate instrument; after successful calibration, displayed haze value shall be 0; c) Select test light source; d) Place specimen between clamps, ensure flatness, press test button, record haze and light transmittance values displayed; e) Test minimum of three specimens sequentially; report arithmetic mean as final haze and light transmittance result, rounded to two decimal places.