Background Statement for SEMI Draft Document 5379B Revision to D36-0306, TERMINOLOGY FOR LCD BACKLIGHT UNIT Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document. Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, patented technology is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided. Background As the technologies of backlight unit have been developed consistently, new terms and definitions for those have been also created. However there are no updated standards ever since SEMI D36-0306, Terminology for LCD Backlight Unit. So it is necessary to revise and update the document to keep up with the latest technology. This standard will be useful to understand terms and definitions for the new technologies of BLU. 5379 and 5379A were issued Revision Control Date Version Name Edits 03-Jan-2012 1.0 SangKyoo Jeon First version of this ballot placed into the template. 06-Apr-2012 2.0 SangKyoo Jeon Update 5 Terminology mainly. 08-Aug-2012 3.0 SangKyoo Jeon Update 5 Terminology mainly. This revision control records activity within the task force as well as formal submit and resubmit dates and results per SEMI. Entries have been made by the task force. Review and Adjudication Information Task Force Adjudication Committee Adjudication Group: Korea Backlight Measurement TF Korea FPD Metrology Technical Committee Date: Friday February 1, 2013 Friday February 1, 2013 Time & Time Zone: 10:00 14:00 14:00 17:00 Location: SEMI Korea office SEMI Korea office City, State/Country: Seoul, Korea Seoul, Korea Leader(s): SangKyoo Jeon (KILT), skjeon@kilt.re.kr Jong Seo Lee (Samsung Electronics) Il-Ho Kim (LMS) Document Originator(s) SangKyoo Jeon (KILT), skjeon@kilt.re.kr SangKyoo Jeon (KILT), skjeon@kilt.re.kr Standards Staff: Natalie Shim (SEMI Korea) 82.2.531.7808 eshim@semi.org Natalie Shim (SEMI Korea) 82.2.531.7808 eshim@semi.org
Note in the proposals, the added text is typically highlighted in blue and underlined. Removed text is typically denoted in blue with double strikeout marks. These markings are for highlight in the ballot only. They are not proposed to be included in the updated standard. Where the proposals show text extracted from the existing standard, any references in the text are aligned with current section numbering. However, recognize that various proposals may add or remove sections, requiring adjustment of references. This ballot assumes that SEMI will adjust these references prior to publication.
SEMI Draft Document 5379B REVISION TO D36-0306, TERMINOLOGY FOR LCD BACKLIGHT UNIT 1 Purpose 1.1 These terms and definitions describe various components and characteristics of backlight units used for light sources of liquid crystal displays. This standard will be helpful to unify terminologies used for backlight units, which will improve manufacturing efficiency by saving manufacturing cost and time. 2 Scope 2.1 This standard is applicable to backlight units. The standard includes the terminologies of components used in backlight units, inspection and measurement used in backlight unit industry as well as panel and instrument industry. The other areas are handled in other SEMI standard documents. NOTICE: SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their use. It is the responsibility of the users of the Documents to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use. 3 Limitations 3.1 In this standard, our target is limited to backlight units and to define their general terminology. Hence any special term used for critical purpose is not mentioned. For example, we do not define special terms depending on personal emotion and any detail or specific components depending on special or general purpose. 3.2 The definition of lamp components which is out of this standard s scope follows the terminologies used in lighting industry or other standards. See 4.2 4 Referenced Standards and Documents 4.1 CIE Standards1 CIE 1931 color space, CIE 1976 UCS 4.2 IEC 60050-845 International Electro Technical Vocabulary, Lighting Vocabulary 4.1 IEC Standards 2 IEC 60050-845 International Electrotechnical Vocabulary Part 845: Lighting IEC 62031 LED modules for general lighting Safety specifications NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions. 5 Terminology 5.1 General Terminology 5.1.1 Definition of Backlight Unit 5.1.1.1 A backlight unit (BLU) is the kind of light source positioned at the backside of a liquid crystal panel. Since LCDs are non-emissive display devices, it needs light source essentially. 5.1.2 Structure of BLUs 5.1.2.1 As an initial light source, cold cathode fluorescence lamp (CCFL) is used at the bottom or the lateral side of BLUs. The light emitted from CCFLs is entered into a light guide plate (LGP). Here light is spread out to be twodimensional light source at the back surface of a LGP or inside of a LGP. Two-dimensional light is sometimes defused by diffusion sheets or converted by prism sheets respectively. And final light comes into human eyes. 1 CIE International Commission on Illumination, Kegelgasse 27, A-1030 Vienna, Austria 2 International Electrotechnical Commission, 3, rue de Varembe, P.O. Box 131, CH-1211 Geneva 20, Switzerland Page 1
a g f e d c b Figure 1 General structures of side (lateral) type (left) and direct type (right) BLU; from a to g, each components indicates a CCFL, a reflection sheet, a light guide plate, a diffusion sheet, two prism sheets, a protection sheet and panel respectively. 5.2 Components The following measurement items are recommended for BLU but these items depend on user requirements if they are specified. 5.2.1 cold cathode fluorescence lamp the fluorescence lamp with cold cathode, in which the glow discharge is generated by the secondary emission of electrons from the cathode. With the fluorescence material coated on the inner surface of the lamp excited by the ultraviolet ray from the positive column, the lamp emits visible ray. 5.2.2 reflection sheet the sheet that reflects the light to prevent the loss of the light toward the back side of the BLU. 5.2.3 light guide plate an optical component used to guide and diffuse light from a light source. 5.2.4 diffusion sheet the sheet which diffuses incident light toward panel. 5.2.5 prism sheet the film which improves condensation efficiency and brightness by optimizing the prism shape, in general. 5.2.6 protection sheet the sheet placed on the top of BLU for protecting other components from damage of outside. 5.2.7 frame the frame to make the components of the BLU stably combined. 5.2.8 electrode the conductor, the part to supply the power into the lamp. It releases the electron by the electric current. 5.2.9 hot (electrode) the electrode connected with the high-voltage side (hot side) of the inverter. 5.2.10 ground (electrode) the opposite electrode of the hot electrode in the lamp, which is connected with the low-voltage side (ground side) of the inverter. 5.2.11 inverter the circuit device to convert the low voltage DC into the high voltage RF in order to light on the CCFL. 5.2.12 lamp the light source of the BLU. A CCFL is mainly used. 5.2.13 lamp assembly the lamp and the parts directly mounted on the lamp. 5.2.14 lamp cover the part protecting lamp. It makes the light emitted from the luminance factor be incident into the light guide plate. 5.2.15 lamp holder the part which protects the lamp from external impact (collision and contact) and protects it so that no high voltage is directly impressed around the lamp input parts (electrode terminals). 5.2.16 lamp ring the part that protects lamp from the fragility. a g f d b Page 2
5.2.17 mercury a discharge gas and an emission source of ultraviolet. The symbol of the element in the periodic table is Hg. 5.2.18 mixing gas the gas mixed Neon and Argon gas etc is needed to open and maintain the discharge. 5.2.19 phosphor the substance with commonly red, blue and green color phosphor that transfers the ultraviolet came from the mercury to the visible ray. 5.2.20 shrinkage tube the part consisting of insulation material, which contacts and insulates a part by shrinking. 5.2.21 adhesive tape the tape to be used for adhering to the components of the BLU each other. 5.2.22 back cover the device that complements fragile part of the lamp, etc. by means of utensil. 5.2.23 clip the part fixing the sheet on the frame to prevent flux and looseness of sheet. 5.3 Characteristics The following measurement items are recommended for BLUs but these items depend on user requirement if they are specified. 5.3.1 luminance the luminous flux from the surface per unit solid angle per unit area in a given direction. Unit: cd/m2 5.3.2 average luminance average value of measured luminance. 5.3.3 maximum luminance maximum value among the measured luminance. 5.3.4 minimum luminance minimum value among the measured luminance. 5.3.5 luminance uniformity the value that indicates the uniformity of luminance for the measured point. And the value is obtained by selecting one or multiple among below equations. a) (maximum/minimum) 100 b) (minimum/maximum) 100 c) [(maximum-minimum)/maximum] 100 d) [(maximum-minimum)/average] 100 where average = Σ(i n)/n 5.3.6 center point the position corresponding to the center of active area of BLU. 5.3.7 chromaticity the indication of the suitable color for the mark of same color, namely the spectrodistribution-chart (λ) of the measured light source. The light source color is indicated by the 3 measured stimulus values X, Y, Z (the quality of stimulus evoking the primary color sense) at the sensitivity of eye (2º). Tri-stimulus values: X, Y, Z x = X/(X + Y + Z), y = Y/(X + Y + Z), z = Z/(X + Y + Z), x + y + z = 1 (Referred by CIE 1931 color space) 5.3.8 life time the shorter of following (1) or (2). (1) a period of the time when the intensity of light falls to the specified regulated value (for example 50%) (2) a period of the time when the lamp starts to get an abnormal discharge 5.3.9 correlated color temperature (CCT) a term used to describe the color of a light source whose chromaticity lies close to the Planckian (black body) locus on a CIE chromaticity diagram, specially, it is the temperature of a black body radiator which produces the chromaticity most similar to that of the light source evaluated. It is usually expressed in degree Kelvin. 5.3.10 surface temperature the surface temperature of the lamp and BLU. Page 3
Unit: C 5.3.11 turn-on test the test for checking turn-on and off of the BLU. 5.3.12 appearance test the test for appearance inspection of the BLU. 5.3.13 reliability test the test for checking the changes of the BLU quality and the size of parts etc, after BLU lighting in various environment and lighting conditions. (ex: temperature 60 C, humidity 75%, aging time 96hr, 250hr, 500hr) 5.3.14 efficiency the ratio of total light fluxes generated by the lamp and consumed electric power of the lamp. Unit: lm / W (lumen/watt) 5.4 Equipment 5.4.1 photometer the equipment that measures the luminance. 5.4.2 colorimeter the equipment that measures the luminance and/or chromaticity. 5.4.3 spectroradiometer the equipment that measures the spectral energy radiated by a source. The spectral data can be used to calculate photometric and colorimetric parameters. 6 Proposals 5.1 Abbreviations and Acronyms 5.1.1 BLU backlight unit 5.1.2 CCFL cold cathode fluorescent lamp 5.1.3 EEFL external electrode fluorescent lamp 5.1.4 LED light emitting diode 5.1.5 LGP light guide plate 5.2 Definitions of Backlight Unit 5.2.1 adhesive tape the tape to be used for adhering to the components of the BLU each other. 5.2.2 backlight unit the kind of light source positioned at the backside of a liquid crystal panel. Since LCDs are non-emissive display devices, it needs light source essentially. 5.2.2.1 direct type BLU the type of light source that is positioned behind a liquid crystal panel, and the light is emitted to the front (see Fig. 1). 5.2.2.2 edge type BLU the type of light source that is positioned at the side of light guide plate, and right after light is reflected from LGP, it is changed to surface illuminant (see Fig. 2). 5.2.3 back cover the device that complements fragile part of the lamp, etc. by means of utensil. 5.2.4 clip the part fixing the sheet on the frame to prevent flux and looseness of sheet. 5.2.5 cold cathode fluorescent lamp the fluorescent lamp with cold cathode, in which the glow discharge is generated by the secondary emission of electrons from the cathode. With the fluorescence material coated on the inner surface of the lamp excited by the ultraviolet ray from the positive column, the lamp emits visible ray. 5.2.6 dc-dc converter the electronic circuit which converts a source of direct current from one voltage level to another. 5.2.7 diffuser sheet the sheet which diffuses incident light toward panel. 5.2.8 efficiency the ratio of total light fluxes generated by the lamp and consumed electric power of the lamp. Unit: lm / W (lumen/watt) 5.2.9 electrode the conductor, the part to supply the power into the lamp. It releases the electron by the electric current. Page 4
5.2.10 external electrode fluorescent lamp the sealed glass lamp with metal cap or conductive paint on the end of tube. With the fluorescence material coated on the inner surface of the lamp excited by the ultraviolet ray from the positive column, the lamp emits visible ray. 5.2.11 frame the frame to make the components of the BLU stably combined. 5.2.12 ground (electrode) the opposite electrode of the hot electrode in the lamp, which is connected with the low-voltage side (ground side) of the inverter. 5.2.13 hot (electrode) the electrode connected with the high-voltage side (hot side) of the inverter. 5.2.14 inverter the circuit device to convert the low voltage DC into the high voltage RF in order to light on the CCFL or EEFL 5.2.15 lamp the light source of the BLU. CCFL, EEFL or LED module can be used as a light source. 5.2.16 lamp cover the part protecting lamp. Light source generally emits light in all directions. To reflect the light emitted from light source into the light guide plate with the minimum light loss, it is made by the materials having the superior reflectivity. 5.2.17 lamp holder the part which protects the lamp from external impact (collision and contact) and protects it so that no high voltage is directly impressed around the lamp input parts (electrode terminals). 5.2.18 lamp ring the part that protects lamp from the fragility. 5.2.19 life time the shorter of following (1) or (2). (3) a period of the time when the intensity of light falls to the specified regulated value (for example 50%) (4) a period of the time when the lamp starts to get an abnormal discharge 5.2.20 light emitting diode solid state device embodying a p-n junction, emitting optical radiation when exicted by an electric current. 5.2.21 light emitting diode module unit supplied as a light source. In addition to one or more LEDs, it may contain further components, e.g. optical, mechanical, electrical and electronic. 5.2.22 light guide plate an optical component used to guide and diffuse light from a light source. 5.2.23 mixing gas the gas mixed Neon, Argon gas and Mercury etc is needed to open and maintain the discharge. 5.2.24 prism sheet the film which improves condensation efficiency and brightness by optimizing the prism shape, in general. 5.2.25 protection sheet the sheet of protecting the optical sheet of BLU from the external shocks or contaminations. 5.2.26 phosphor the substance with commonly red, blue and green color phosphor that transfers the ultraviolet came from the mercury to the visible ray. 5.2.27 reflection sheet the sheet that reflects the light to prevent the loss of the light toward the back side of the BLU. 5.2.28 shrinkage tube the part consisting of insulation material, which contacts and insulates a part by shrinking. 5.2.29 Structure of BLUs as an initial light source, cold cathode fluorescence lamp (CCFL), external electrode fluorescent lamp (EEFL) or light emitting diode (LED) module are used at the bottom or the lateral side of BLUs. The light emitted from those are entered into a light guide plate (LGP). Here light is spread out to be twodimensional light source at the back surface of a LGP or inside of a LGP. Two-dimensional light is sometimes defused by diffusion sheets or converted by prism sheets respectively. And final light comes into LCD cell. 5.2.30 turn-on test the test for checking turn-on and off of the BLU. Page 5
Figure 1 General structure of direct type BLU Figure 2 General structure of edge type BLU NOTICE: Semiconductor Equipment and Materials International (SEMI) makes no warranties or representations as to the suitability of the Standards and Safety Guidelines set forth herein for any particular application. The determination of the suitability of the Standard or Safety Guideline is solely the responsibility of the user. Users are cautioned to refer to manufacturer s instructions, product labels, product data sheets, and other relevant literature, respecting any materials or equipment mentioned herein. Standards and Safety Guidelines are subject to change without notice. By publication of this Standard or Safety Guideline, SEMI takes no position respecting the validity of any patent rights or copyrights asserted in connection with any items mentioned in this Standard or Safety Guideline. Users of this Standard or Safety Guideline are expressly advised that determination of any such patent rights or copyrights, and the risk of infringement of such rights are entirely their own responsibility. Page 6