adjusting backlight on lcd panel manufacturer

For the video display developer LCD panels are available in many sizes and resolutions, they are also available with many choices of maximum brightness. The following considers the topic of LCD panel brightness, the choices, the methods for adjusting brightness and some brightness adjustment scenarios.

LCD panels are generally rated as to their maximum brightness level which is expressed in Nits, it is equal to Candela/sqm (cd/m2), and this will be at a particular color temperature as noted in the specification, usually 10,000 K. In terms of a practical understanding, the following is a rough guide:

Outdoor displays range from a low end of 700 nits to typically 1,000 or 1,500nits and up with 2,000~2,500nits and even up to 5,000nits seen with some models. This may include standard LCD panels, custom LCD panels as well as custom cut LCD panels.

Virtually all LCD panels have a LED backlight these days, these are powered by an LED driver board. Brightness control via the driver board will be by one of two methods:

PWM (Pulse Width Modulation): This varies the duty cycle of the backlight “on time” – it is predominant in modern LCD panel LED backlight designs to enable support for digital brightness controls.

Analog: Uses a simple variable voltage to adjust brightness, for example this might be a dial or slider type potentiometer / variable resistor. To see how to enable analog backlight adjustment visit: https://www.digitalview.com/blog/brightness-adjustment/

One of the advantages of LED for the backlight is the range of adjustment that is possible, however it is important to note that the range varies significantly from model to model. Some industrial panels can be turned to very low light levels making them suitable for use in special environments such as at night. Lower cost panels limit the range of brightness to what might be required for typical usage, whereas panels with full range dimming from full off to full on require more complex backlight drivers.

Backlight lifetime: Many LCD panels have a backlight lifetime rating of 50,000 hours (typically measured to half brightness), this can be extended by running the LED backlight at a lower brightness level. Some panels may only offer 30,000 hours as a lower cost solution while other panels may offer up to 100,000 hours for high end applications.

An LCD panel backlight may be constructed so the LED’s are mounted directly behind a light guide diffuser, or they may be mounted along one or more edges of the light guide.

Active backlight: This is a function of some LCD panel backlights to automatically adjust the backlight brightness in response to the image. For more advanced systems there is an LED array making up the LED backlight, this adjusts the brightness in areas localized to the image being shown. This can greatly enhance the brightness across the display and is being used primarily with video, for example on consumer TV sets. It is not useful to all image types, for example a spreadsheet or content like maps or data is not likely to benefit.

Local dimming: Some LCD panels with direct LED may support local dimming so the LED’s are dimmed in response to the image close to them. This will not be at the same resolution as the LCD panel itself but will help greater contrast over the display by enhancing the brightness in bright areas of the image and darkening the image in dark parts of the image.

Both of the above techniques are likely to be more beneficial to certain types of content than others. For example a movie is likely to benefit more than a spreadsheet.

For the LCD monitor manufacturer it is important to consider that any covering over the LCD panel will reduce the brightness. For example the protective glass over a digital signage display, or a touch screen, or a semi-silvered mirror. So if a specific brightness is required the measurement should be taken with these in place.

There are various relatively low cost brightness meters available, typically in the couple of hundred dollars range. It is difficult to comment on the accuracy of these but we have found them to be within 5% of each other, though more importantly they do appear to be quite consistent in measurement so good for measurement comparisons. For more accurate measurement there are light meters from companies such as Minolta that can be calibrated, the cost may run into several thousand dollars.

Examples of light meters costing a few hundred dollars include SpyderX by Datacolor (needs a PC), a handheld meter is the SM208 by Sanpometer (search SM208 meter). Note: Many light meters, including smartphone apps, will be meters used for photography and not give readings in nits (or candelas). LCD panel specifications are typically measured using nits.

PWM and Analog: Most Digital View LCD controllers support PWM and Analog as a method for adjusting the backlight brightness level (this is noted in the column headed “Other” on the controller board summary table: https://www.digitalview.com/controllers/lcd-controllers-home.html. Also see https://www.digitalview.com/blog/brightness-adjustment/ for a guide to using a dial or slider type variable resistor to adjust the backlight.

DPMS (Display Power Management System): The backlight will be automatically turned off after a period if there is no valid video signal being received.

Ambient light sensor: The backlight is adjusted for brightness or powered off depending on ambient light conditions. This uses a light sensor attached to the LCD controller board, see https://www.digitalview.com/blog/light-sensor-app-note/ for more details.

The specifics of the backlight control are documented separately for each LCD controller model (product summary here) in the product manual available for download on the product page.

Note: There are two ways to adjust the perceived brightness of a LCD panel or LCD monitor, the backlight and the black-level. Very often, particularly in the past, the monitor brightness setting adjusted the black-level, this adjusts the LCD but not the backlight.

Color, color temperature etc: In addition to adjusting the brightness other settings may be adjusted as well. For example the color temperature or for example a switch to green monochrome for night vision.

Night-safe lighting (update) : Dual-rail backlights can also be supported. These special backlight enable normal brightness and extreme low level brightness with custom night-safe lighting. Contact us for details.

Note: We have a blog on methods for implementing an ambient light sensor with Digital View LCD controller boards to automatically adjust the backlight or system power, see: Ambient Light Sensor

Update March 2019: Most of the above remains unchanged except for the increased availability of high bright LCD panels of around the 1,000 nit to 2,500 nit range. AUO for example has a number of large size LCD panels with 1,500 nit brightness for the digital signage market. Tianma has panels under 20″ with 1,000 nit to 1,500 nit brightness for various outdoor applications.

The other change is that high bright panels are now increasing edge-lit, this makes the panels thinner and these panels tend to use less power than the previous models. One of the benefits for monitor designers is easier heat management and reduced overall display system costs.

The contrast ratio (CR) is a property of a display system, defined as the ratio of the luminance of the brightest color (white) to that of the darkest color (black) that the system is capable of producing.

If the LCD contrast is too low, it is hard to read. Different applications have different contrast requirement. For normal reading, the contrast needs to be >2; for medical, the contrast needs to be >10, for welding helmet, contrast should be >1,000.

The higher the efficiency, the better of the LCD contrast . It is especially important for negative display. Change from 98% to 99.9% polarizer, the contrast can increase from 45 to over 1000 for negative LCD, but for positive LCD, the contrast increases from 7 to 10 for positive LCD.

Positive LCD to Negative LCD (When the LCD is used indoor or dark environment, The contrast will increase a lot, but it will not display well with ambient light only, it is also more expensive)

For negative display, black mask can block the light bleeding, the contrast can be improved. Black mask can be done either outside cell (low cost) and inside cell (high cost).

Important technical improvements of LCD, such as LED backlighting and wide viewing Angle, are directly related to LCD. And account for an LCD display 80% of the cost of the LCD panel, enough to show that the LCD panel is the core part of the entire display, the quality of the LCD panel, can be said to directly determine the quality of an LCD display.

The production of civil LCD displays is just an assembly process. The LCD panel, the main control circuit, shell, and other parts of the main assembly, basically will not have too complex technical problems.

Does this mean that LCDS are low-tech products? In fact, it is not. The production and manufacturing process of the LCD panels is very complicated, requiring at least 300 process processes. The whole process needs to be carried out in a dust-free environment and with precise technology.

The general structure of the LCD panel is not very complex, now the structure of the LCD panel is divided into two parts: the LCD panel and the backlight system.

Due to the LCD does not shine, so you need to use another light source to illuminate, the function of the backlight system is to this, but currently used CCFL lamp or LED backlight, don’t have the characteristics of the surface light source, so you need to guide plate, spreadsheet components, such as linear or point sources of light evenly across the surface, in order to make the entire LCD panel on the differences of luminous intensity is the same, but it is very difficult, to achieve the ideal state can be to try to reduce brightness non-uniformity, the backlight system has a lot to the test of design and workmanship.

In addition, there is a driving IC and printed circuit board beside the LCD panel, which is mainly used to control the rotation of LCD molecules in the LCD panel and the transmission of display signals. The LCD plate is thin and translucent without electricity. It is roughly shaped like a sandwich, with an LCD sandwiched between a layer of TFT glass and a layer of colored filters.

LCD with light refraction properties of solid crystals, with fluid flow characteristics at the same time, under the drive of the electrode, can be arranged in a way that, in accordance with the master want to control the strength of the light through, and then on the color filter, through the red, green, blue three colors of each pixel toning, eventually get the full-screen image.

According to the functional division, the LCD panel can be divided into the LCD panel and the backlight system. However, to produce an LCD panel, it needs to go through three complicated processes, namely, the manufacturing process of the front segment Array,the manufacturing process of the middle segment Cell, and the assembly of the rear segment module. Today we will be here, for you in detail to introduce the production of the LCD panel manufacturing process.

The manufacturing process of the LCD panel Array is mainly composed of four parts: film, yellow light, etch and peel film. If we just look at it in this way, many netizens do not understand the specific meaning of these four steps and why they do so.

First of all, the motion and arrangement of LCD molecules need electrons to drive them. Therefore, on the TFT glass, the carrier of LCD, there must be conductive parts to control the motion of LCD. In this case, we use ITO (Indium Tin Oxide) to do this.ITO is transparent and also acts as a thin-film conductive crystal so that it doesn’t block the backlight.

The different arrangement of LCD molecules and the rapid motion change can ensure that each pixel displays the corresponding color accurately and the image changes accurately and quickly, which requires the precision of LCD molecule control.ITO film needs special treatment, just like printing the circuit on the PCB board, drawing the conductive circuit on the whole LCD board.

First, the ITO film layer needs to be deposited on the TFT glass, so that there is a smooth and uniform ITO film on the whole TFT glass. Then, using ionized water, the ITO glass is cleaned and ready for the next step.

Next, a photoresist is applied to the glass on which ITO film is deposited, and a uniform photoresist layer is formed on the ITO glass. After baking for a period of time, the solvent of the photoresist was partially volatilized to increase the adhesion of the photoresist material to the ITO glass.

Ultraviolet light (UV) is used to illuminate the surface of the photoresist through a pre-made electrode pattern mask, which causes the photoresist layer to react. The photoresist is selectively exposed under ultraviolet light by covering the photoresist on the glass coated with the photoresist.

The exposed part of the photoresist is then washed away with the developer, leaving only the unexposed part, and the dissolved photoresist is then washed away with deionized water.

Then etch off the ITO film without photoresist covering with appropriate acid etching solution, and only retain the ITO film under the photoresist. ITO glass is conductive glass (In2O3 and SnO2). The ITO film not covered by photoresist is easy to react with acid, while the ITO film covered by photoresist can be retained to obtain the corresponding wire electrode.

Stripping: High concentration of alkali solution (NaOH solution) is used as a stripping solution to peel off the remaining photoresist on the glass so that ITO glass can form ITO graphics exactly consistent with the photolithography mask.

Rinse the basic label of glass with an organic solution and remove the photolithographic tape after reaction to keep the glass clean. This completes the first thin-film conductive crystal process, which generally requires at least five identical processes to form a complex and sophisticated pattern of electrodes on the glass.

This completes the previous Array process. It is not difficult to see from the whole process that ITO film is deposited, photoresist coated, exposed, developed, and etched on TFT glass, and finally, ITO electrode pattern designed in the early stage is formed on TFT glass to control the movement of LCD molecules on the glass. The general steps of the whole production process are not complicated, but the technical details and precautions are very complicated, so we will not introduce them here. Interested friends can consult relevant materials by themselves.

The glass that the LCD board uses makes a craft also very exquisite. (The manufacturing process flow of the LCD display screen)At present, the world’s largest LCD panel glass, mainly by the United States Corning, Japan Asahi glass manufacturers, located in the upstream of the production of LCD panel, these manufacturers have mastered the glass production technology patents. A few months ago, the earthquake caused a corning glass furnace shutdown incident, which has caused a certain impact on the LCD panel industry, you can see its position in the industry.

As mentioned earlier, the LCD panel is structured like a sandwich, with an LCD sandwiched between the lower TFT glass and the upper color filter. The terminal Cell process in LCD panel manufacturing involves the TFT glass being glued to the top and bottom of a colored filter, but this is not a simple bonding process that requires a lot of technical detail.

As you can see from the figure above, the glass is divided into 6 pieces of the same size. In other words, the LCD made from this glass is finally cut into 6 pieces, and the size of each piece is the final size. When the glass is cast, the specifications and sizes of each glass have been designed in advance.

Then, the organic polymer directional material is coated on the surface of the glass, that is, a uniform directional layer is applied to the appropriate position of ITO glass by the method of selective coating. Meanwhile, the directional layer is cured.

Directional friction:Flannelette material is used to rub the surface of the layer in a specific direction so that the LCD molecules can be arranged along the friction direction of the aligned layer in the future to ensure the consistency of the arrangement of LCD molecules. After the alignment friction, there will be some contaminants such as flannelette thread, which need to be washed away through a special cleaning process.

After the TFT glass substrate is cleaned, a sealant coating is applied to allow the TFT glass substrate to be bonded to the color filter and to prevent LCD outflow.

Finally, the conductive adhesive is applied to the frame in the bonding direction of the glass of the color filter to ensure that external electrons can flow into the LCD layer. Then, according to the bonding mark on the TFT glass substrate and the color filter, two pieces of glass are bonded together, and the bonding material is solidified at high temperatures to make the upper and lower glasses fit statically.

Color filters are very important components of LCD panels. Manufacturers of color filters, like glass substrate manufacturers, are upstream of LCD panel manufacturers. Their oversupply or undersupply can directly affect the production schedule of LCD panels and indirectly affect the end market.

As can be seen from the above figure, each LCD panel is left with two edges after cutting. What is it used for? You can find the answer in the later module process

Finally, a polarizer is placed on both sides of each LCD substrate, with the horizontal polarizer facing outwards and the vertical polarizer facing inwards.

A polarizer is an optical plate that allows only light from a certain direction to pass through. It is an optical element that converts natural light into straight polarized light. The mechanism of action is to make the vertical direction light pass through the straight incident light after passing through the vertical polarizer, and the other horizontal direction light is absorbed, or use reflection and scattering and other effects to make its shade.

When making LCD panel, must up and down each use one, and presents the alternating direction, when has the electric field and does not have the electric field, causes the light to produce the phase difference and to present the light and dark state, uses in the display subtitle or the pattern.

The rear Module manufacturing process is mainly the integration of the drive IC pressing of the LCD substrate and the printed circuit board. This part can transmit the display signal received from the main control circuit to the drive IC to drive the LCD molecules to rotate and display the image. In addition, the backlight part will be integrated with the LCD substrate at this stage, and the complete LCD panel is completed.

Firstly, the heteroconductive adhesive is pressed on the two edges, which allows external electrons to enter the LCD substrate layer and acts as a bridge for electronic transmission

Next is the drive IC press. The main function of the drive IC is to output the required voltage to each pixel and control the degree of torsion of the LCD molecules. The drive IC is divided into two types. The source drive IC located in the X-axis is responsible for the input of data. It is characterized by high frequency and has an image function. The gate drive IC located in the Y-axis is responsible for the degree and speed of torsion of LCD molecules, which directly affects the response time of the LCD display. However, there are already many LCD panels that only have driving IC in the X-axis direction, perhaps because the Y-axis drive IC function has been integrated and simplified.

The press of the flexible circuit board can transmit data signals and act as the bridge between the external printed circuit and LCD. It can be bent and thus becomes a flexible or flexible circuit board

The manufacturing process of the LCD substrate still has a lot of details and matters needing attention, for example, rinse with clean, dry, dry, dry, ultrasonic cleaning, exposure, development and so on and so on, all have very strict technical details and requirements, so as to produce qualified eyes panel, interested friends can consult relevant technical information by a search engine.

LCD (LC) is a kind of LCD, which has the properties of light transmission and refraction of solid Crystal, as well as the flow property of Liquid. It is because of this property that it will be applied to the display field.

However, LCD does not emit light autonomously, so the display equipment using LCD as the display medium needs to be equipped with another backlight system.

First, a backplate is needed as the carrier of the light source. The common light source for LCD display equipment is CCFL cold cathode backlight, but it has started to switch to an LED backlight, but either one needs a backplate as the carrier.

CCFL backlight has been with LCD for a long time. Compared with LED backlight, CCFL backlight has many defects. However, it has gradually evolved to save 50% of the lamp and enhance the transmittance of the LCD panel, so as to achieve the purpose of energy-saving.

With the rapid development of LED in the field of lighting, the cost has been greatly reduced.LCD panels have also started to use LED as the backlight on a large scale. Currently, in order to control costs, an LED backlight is placed on the side rather than on the backplate, which can reduce the number of LED grains.

However, no matter CCFL backlight or LED backlight is placed in various ways, the nature of the backlight source cannot be a surface light source, but a linear light source or point light source. Therefore, other components are needed to evenly distribute the light to the whole surface. This task is accomplished by the diffuser plate and diffuser plate.

On the transparent diffuser plate, point-like printing can block part of the light. The LED backlight on the side drives the light from the side of the diffuser plate, and the light reflects and refracts back and forth in the diffuser plate, distributing the light evenly to the whole surface. Point-like printing blocks part of the light, screening the light evenly like a sieve.

At the top of the diffusion plate, there will be 3~4 diffuser pieces, constantly uniform light to the whole surface, improve the uniformity of light, which is directly related to the LCD panel display effect. Professional LCD in order to better control the brightness uniformity of the screen, panel procurement, the later backlight control circuit, will make great efforts to ensure the quality of the panel.

The backlight system also includes a backlight module laminator, located behind the backplane. In the CCFL backlight era, you can often see the long strip laminator like the one above, with each coil responsible for a set of tubes.

However, it is much simpler to use a side white LED as a backlight. The small circuit board on the far left of the figure above is the backlight of the LED.

This is the general structure of the backlight system. Since I have never seen the backlight mode of R.G.B LED, I cannot tell you what the backlight mode is like. I will share it with you when I see it in the future.

Since the LCD substrate and the backlight system are not fixed by bonding, a metal or rubber frame is needed to be added to the outer layer to fix the LCD substrate and the backlight system.

After the period of the Module, the process is completed in LCM (LCDModule) factory, the core of this part of the basic does not involve the use of LCD manufacturing technology, mainly is some assembly work, so some machine panel factories such as chi mei, Korea department such as Samsung panel factory, all set with LCM factories in mainland China, Duan Mo group after the LCD panel assembly, so that we can convenient mainland area each big monitor procurement contract with LCD TV manufacturers, can reduce the human in the whole manufacturing and transportation costs.

However, neither Taiwan nor Korea has any intention to set up factories in mainland China for the LCD panel front and middle manufacturing process involving core technologies. Therefore, there is still a long way to go for China to have its own LCD panel industry.

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First, the display screen on a sunlight readable/outdoor readable LCD should be bright enough so that the display is visible under strong sunlight. Second, the display contrast ratio must be maintained at 5 to 1 or higher.

Although a display with less than 500 nits screen brightness and a mere 2 to 1 contrast ratio can be read in outdoor environments, the quality of the display will be extremely poor. At i-Tech, a truly sunlight readable display is typically considered to be an LCD with 1000 nits or greater screen brightness with a contrast ratio greater than 5 to 1. In outdoor environments under the shade, such a display can provide an excellent image quality.

Luminance is the scientific term for hotopic Brightness?which specifies the visual brightness of an object. In layman"s terminology, it is commonly referred to as brightness? Luminance is specified in candelas per square meter (Cd/m2) or nits. In the US, the British unit Foot-lamberts (fL) is also frequently used. To convert from fL to nits, multiply the number in fL by 3.426 (i.e. 1 fL = 3.426 nits).

Luminance is a major determinant of perceived picture quality in an LCD. The importance of luminance is enhanced by the fact that the human mind will react more positively to brightly illuminated scenes and objects. Users are typically more drawn to brighter displays that are more pleasing to the eye and easier to read. In indoor environments, a standard active-matrix LCD with a screen luminance around 250 nits looks good. However, a sunlight readable LCD with a screen luminance of 1,000 will look even more beautiful.

Contrast ratio (CR) is the ratio of luminance between the brightest �white� and the darkest �black� that can be produced on a display. CR is another major determinant of perceived picture quality. If a picture has high CR, you will judge it to be sharper and more crisp than a picture with lower CR. For example, a typical newspaper picture has a CR of about 5 to 7, whereas a high quality magazine picture has a CR that is greater than 15. Therefore, the magazine picture will look better even if the resolution is the same as that of the newspaper picture.

A typical AMLCD exhibits a CR between 300 to 700 when measured in a dark room. However, the CR on the same unit measured under ambient illumination is drastically lowered due to surface reflection (glare). For example, a standard 200 nit LCD measured in a dark room has a 300 CR, but will have less than a 2 CR under strong direct sunlight. This is due to the fact that surface glare increases the luminance by over 200 nits both on the white and the black that are produced on the display screen. The result is that the luminance of the white is slightly over 400 nits, and the luminance of the black is over 200 nits. The CR ratio then becomes less than 2 and the picture quality is drastically reduced.

i-Tech sunlight readable LCDs with 1500 nits screen brightness will have a CR over 8 with the same amount of glare under the same strong sunlight, making the picture quality on these units extremely good. For further reading on contrast ratio, please see Tech Note 0101, Page 2, the Display Contrast Ratio.

The viewing angle is the angle at which the image quality of an LCD degrades and becomes unacceptable for the intended application. As the observer physically moves to the sides of the LCD, the images on an LCD degrade in three ways. First, the luminance drops. Second, the contrast ratio usually drops off at large angles. Third, the colors may shift. The definition of the viewing angle of an LCD is not absolute as it will depend on your application.

Most LCD manufacturers define viewing angle as the angles where the CR (contrast ratio)^3 10. For LCDs designed for less demanding applications, the viewing angle is sometimes defined as the angles where the CR^3 5.

For LCDs used in outdoor applications, defining the viewing angle based on CR alone is not adequate. Under very bright ambient light, the display is hardly visible when the screen luminance drops below 200 nits. Therefore, i-Tech defines the viewing angles based on both the CR and the Luminance.

All LCD backlights powered by cold cathode fluorescent lamps (CCFL) require inverters. An inverter is an electronic circuit that transforms a DC voltage to an AC voltage, which drives the CCFLs. i-Tech Technology manufactures inverters for all its products. Additionally, Applied Concepts and ERG also provide inverters for our products as well.

The dimming range or dimming ratio of an inverter specifies its capability of performing backlight luminance adjustment. For inverters used in notebook computers and LCD monitors, the backlight luminance can be adjusted typically over a dimming range of less than 10:1. That is, the luminance is adjusted from 100% down to about 10%.

For very high brightness backlights used in i-Tech Technology sunlight readable LCD modules, the inverters must be able to provide a much wider dimming range. Otherwise, the LCD screen will be too bright during nighttime conditions. Therefore, our inverters provide a typical dimming ratio of 200:1, meaning that the luminance can be adjusted from 100% down to 0.5%.

Dimming capabilities are beneficial because lowering the backlight luminance will result in a lengthening of the backlight life. It also lowers the power consumption and the related thermal management issues.

Any high brightness backlight system will consume a significant amount of power, thereby increasing the LCD temperature. The brighter the backlight, the greater the thermal issue. Additionally, if the LCD is used under sunlight, additional heat will be generated as a result of sunlight exposure. Temperature issues can be handled through proper thermal management design.

We provide TFT LCD with reflective mode of illumination without compromising its transmissive illumination. With the imposed reflective function, the modified LCD can reflect the ambient light passing the LCD cell and utilize the reflected light beams as its illumination. The stronger the ambient light is, the brighter the LCD will appear. As a result, the modified LCD is viewable under all lighting conditions including direct sunlight regardless the LCD"s original brightness.

The market demands for outdoor LCD applications are expanding, such as mobile navigator/video systems, PDA, personal organizer, Tablet PC, notebook computer, and Kiosk display etc. However, a regular transmissive LCD is very difficult to read under strong ambient light. This limits the outdoor applications of a conventional transmissive LCD.

The high bright LCD and the transflective LCD are the solutions generally utilized for outdoor applications. However, both solutions have some shortcomings. Because of the added lamps, high bright LCD creates some undesirable problems, which include high power consumption, excessive heat generation, increased dimensions, electrical circuit alterations, and shortened LCD lifetime. Thus, it is usually troublesome and costly to accommodate a high bright LCD in systems. Though giving good performance under the direct sunlight, the transflective LCD trades of its indoor performances.

Problems noticed in transflective LCD include narrow viewing angle, discoloration, low brightness, and loss of contrast. Moreover, the transflective LCD is currently limited in choice of sizes and resolutions.

On the other hand, a Transflective LCD is readable everywhere including outdoor environments without extra power consumption and excessive heat generation. The indoor viewing qualities are also enhanced. The modified unit fits right back into its original system with no need of any alteration and extra effort. Thus in your choice of size, resolution, and model, a direct sunlight readable LCD is conveniently incorporated into your device.

i-Tech is a premier supplier of optical bonding and performance added passive enhancements for all flat panel . i-Tech Optical Bonding process produces an optical bond between any display cover glass or touch panel, and any size LCD.

In the world of LCD"s, i-Tech takes display enhancement to a new level above all others. Utilizing advanced proprietary optical bonding technology; i-Tech overcomes optical challenges for display product manufacturers at an affordable price. In a wide range of applications, standard liquid crystal appear to "washed out" in high ambient lighting conditions. This wash out is due to excessive reflections and glare caused by bright light.

Commercially available LCDs, especially when protected by a separate cover glass or plastic shield, can not deliver enough brightness to make the display functional in outdoors or in other high ambient light applications. The exclusive Optical Bonding process from i-Tech provides a significant reduction of ambient light reflections at an affordable price, compared to other display enhancement technologies.

Optical Bonding seals either a top cover glass or touch screen directly to the face of the display bezel. Our bonding process eliminates the air-gap between the display and the cover glass, vastly reducing reflective light, which causes visual washout of the display image. Optical Bonding also enhances structural integrity by supporting the LCD assembly with the cover glass. The bond maintains perfect display uniformity while providing shock protection, unlimted humidity protection, and elimination of fogging caused by trapped moisture accumulating in typical air-gap assemblies.

Sunlight viewability of a display depends on the differences between "lumination" and "illumination" of the display. The lumination of the display is its brightness. A display"s brightness, typically referred to as a Nit (Candela per meter/2) is the amount of light energy coming out of the display. Illumination is the amount of ambient light shining onto a display. The readability of a display is dependant on the amount of light that is being reflected off of the display.

Light travels through a variety of transparent materials; such as air, glass, plastic, and even water. These material"s abilty to transmit light is measured by their "indices of refraction". As light transfers from one material to another, such as air to glass, the differences the index of refraction will cause reflection. In the case of an air-to-glass interface, the reflection will be slightly less than 5% of the ambient light. All surfaces that have an index mismatch will reflect and the reflection is cumulative. In the case of a standard glass or plastic window, there are three surfaces with an index mismatch which will create a total relfection of nearly 15% of the ambient light. If the total reflection (in nits) is close to the displays brightness, the contrast of the display will be reduced to the point where the display"s readabilty is reduced to unacceptable levels.

Optical Bonding from i-Tech is a solid, transparent bond which optically couples the front cover glass or touch screen directly to the face of the display. This internal bond eliminates reflection from the two internal layers. The outer surface of the window is treated with anti-reflecting coatings which matches the front surface of the glass with the index of refraction of air. This combination reduces the total reflection of the display and front cover glass to less than 2% of the ambient light. A reduction of reflection of this level, all but eliminates reflective loss in most ambient lighting conditions. With reductions of this level, displays with 300-500 nits of brightness will be viewable in daylight or indirect lighting conditions. At 500-800 nits brightness, most displays will be completely sunlight viewable.

Aside from the optical quality, Optical Bonding elminates the air-gap which prevents heat build-up from the "greenhouse" effect and prevents fogging from moisture or contamination from dirt or particles. It also offers shock protection and other damage to the LCD itself.

iTech IP65 Front and Full IP66 Chassis are designed for those applications require IP ( Ingress Protection ) feature, like chemical industry, food industry and medical industry. However, the IP65 Front and Full IP66 chassis might get moisture condensation issue for the applications under direct sunlight.

We provide two different choices of optical enhancement solutions that include anti-reflective coated and/or anti-glare protection glass. These technologies can be widely used in outdoor and indoor environment by enhancing optical performance of displays.

The anti-reflective coatings on the protection glass have excellent performance in tough ambient light conditions. With the normal glass, the strong reflection of the ambient light diminishes visibility and causes problems for viewer. Our special anti-reflective coated protection glass can increase contrast by enhancing light transmission rate over 95% (light reflectance rate less than 5%) and can effectively diminish the mirror images. The multi-layer vapor deposition coating either on one side or two sides of glass is designed to minimize reflectance and maximize transmittance.

Another solution, with an anti-glare (AG) coated protection glass, a microscopically rough surface laminated onto the topmost of display can diffuse glare. The chemically etched glass that has a slightly textured finish can reduce reflection by scattering light directed on its surface. It can soften the image of direct light sources visible in the reflection of the viewing area.

Clearing Point - The temperature at which the liquid crystal fluid changes from a nematic into an isotropic state. In practice, a positive image LCD will turn totally black at this temperature and will therefore be unreadable. Because the clearing point is different for every fluid type, ask for design assistance from your supplier if high temperature operation is critical in your application.

Also, for most cases, both TN, HTN and STN utilize the phase known as nematic for display purpose. Within this phase, the liquid crystal has a "rod shape" exists within the solution which has fast response and has excellent electro-optic properties. This phase, however, only exists within a limited temperature range. The higher end of this temperature range is known as clearing point, above which, the liquid crystal lost its birefrigerance properties and cannot bend the light path anymore. Thus the polarizer will then be the only factor which affect incoming and out coming light. When the LCD is cooled down to below its clearing point, the display should be working again. The temperature for the clearing point varies greatly from material to material and you should contact our engineers regarding what you have. Normally a safe margin should be used to avoid clearing point when designing the display.

Isotropic Stage The point where the fluid heats or cools to where it is no longer in the twisted nematic state. Since the molecules can no longer twist light, all incoming light is absorbed.

The lighter sensor measures the outside brightness according to different environments and sends the information to display. Display will adjust the brightness automatically.

With lighter condition (Outdoor/Sun-light) the brightness will increase; in the opposite condition, the brightness will be decreased to fit darker environment.

Light sensor detect the change of illumination outside, then it send the signal to MCU via I�2C interface. MCU will ask inverter to switch the brightness if the outside illumination was change over the default. MCU will transmit PWM signal to the inverter, amd the inverter will change the brightness of panel.

Each step has its own illuminate range according different environment illumination. This technology makes the use of visual application more friendly and intelligently.

Winmate �light sensor� technology are now available for 8.4�, 10.4�,12.1�, 15�, 17�, and 19� LCD with specific panel option. Please contact with sales for more detail information.

TouchScreen Solutions is a specialist manufacturer of touchscreens, optical filters to enhance the performance of electronic displays, and transparent composites.

By utilising TouchScreen Solutions�s traditional lamination expertise, touchscreens are designed to provide the highest levels of light transmission, excellent readability and unsurpassed protection against a wide range of physical threats. The touchsacreens are accurate, highly dependable and have a rapid response time

The electronic controls effectively divide the screen into pixel sized sensing cells, using microfine wires which are not visible on a powered display. These wires are connected to a controller board, and an oscillation frequency is established for each wire. Touching the glass causes a change in the frequency of the wires at that particular point, the position of which is calculated and identified by the controller. Unlike other capacitive systems where the operator touches the actual conducting surface of the sensing panel, the active component of the sensor can be embedded up to 25mm from the touch surface ensuring long product life and stability.

The touchscreen can be supplied with the options of anti�glare or anti-reflection coatings, thermal toughening or chemical strengthening and privacy or contrast enhancement filters. The front glass of the touchscreen acts as a dielectric and enhances the capacitance of the touchscreen.

The driver software allows the touchscreen to interface with the host computer�s operating system by emulating the behaviour of a computer �mouse� and translates taps on the touchscreen surface into mouse clicks.

Touchscreen is proven to meet today�s demanding requirements for ATM�s, web phones, ticket machines, medical displays, industrial displays, pay-at-the-pump gas machines, and interactive kiosk systems. The touchscreen is durable and dependable, its construction protects against damage caused by moisture, heat and even vandalism.

The touchscreen comprises a laminated glass sensor, which encompasses the sensing medium, and the control card which connects to the communications port of the computer.

Female D9 serial connector on a 3 metre long, 3 wire, lead. Maximum length of lead - 10 metres. Power supply components in connection -2 diodes, 1 resistor and 1 capacitor .

Simple calibration and set-up with Windows 98, NT, 2000, XP and Linux. Mouse emulation with Select on Touch, Select on Dwell, Select on Release and Drag and Drop.

Recently there many end customer was mislead believing high brightness (over 2000nits, even up to 5000nits) is the better solution. But there are few concerns that the so called extreme high brightness (3000nits to 5000nits) panel manufacturer don"t tell you:

1. How much power consumption is the extreme high brightness LCD? It is very important because all of our outdoor LCD is in completely sealed enclosures keeping it cool is a very huge Challenge. Not mentioned the hot temperature around 40-50C area.

2. Also, you need to determine how far is viewer distance. Because high brightness (3000-5000nits LCD) might Damage eyesight if the viewer is too closed. LCD is design with high resolution for people to see it very closely, so extreme high brightness doesn"t make sense for outdoor LCD. If they want to put on extreme high brightness LCD on roof top to attract audience which LCD is not even big enough for seeing from far away. Most case customer will use LED which is more reliable and cost effective if it is larger than 82".

3. High chance rejection from city sign official. Many LED billboard brightness can goes up to 5000-7000nits, but the local government agency will not approve this brightness, because it is traffic distraction for driver or other people. So, it doesn"t make sense to spend a fortune on extreme high brightness but need to dim it down back to 1000-1500nits.

4. Viewable under sunlight is not just brightness only, it involve contrast ratio, reflection of the front glass and content graphics contrast such as (red and white). Sunlight readable is combination of all above, not just brightness only.

4. Viewable under sunlight is not just brightness only, it involve contrast ratio, reflection of the front glass and content graphics contrast such as (red and white). Sunlight readable is combination of all above, not just brightness only.

3. All the major branded LG and Samsung LCD manufacturer the most brightness that they do is only 1000-2000nits because we believe this major LCD maker already done a study on what is the most feasible and comfortable LCD brightness for outdoor. That"s why all the high brightness (3000-5000nits) maker is after market vendor without any study about the what is most suitable brightness for different applications, only advertising high brightness is not the solution. If you ask these vendor for outdoor enclosure which they will not provide or guaranteed it will work because they know it is a huge Challenge to cool down the display. Just like you are buying a 800 horse power car, but you still need to design the car frame and cooler to make this engine run safely on the road, which this extreme high brightness won"t help you to design that.

This article is about backlights in liquid crystal displays. For the rear window of an automobile, see Car glass. For the lighting design practice, see Backlighting (lighting design). For other uses, see Backlight (disambiguation).

A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination (ambient light or a special light source) to produce a visible image. Backlights illuminate the LCD from the side or back of the display panel, unlike frontlights, which are placed in front of the LCD. Backlights are used in small displays to increase readability in low light conditions such as in wristwatches,smart phones, computer displays and LCD televisions to produce light in a manner similar to a CRT display. A review of some early backlighting schemes for LCDs is given in a report Engineering and Technology History by Peter J. Wild.

Simple types of LCDs such as in pocket calculators are built without an internal light source, requiring external light sources to convey the display image to the user. Most LCD screens, however, are built with an internal light source. Such screens consist of several layers. The backlight is usually the first layer from the back. Light valves then vary the amount of light reaching the eye, by blocking its passage in some way. Most use a fixed polarizing filter and a switching one, to block the undesired light.

An ELP gives off uniform light over its entire surface, but other backlights frequently employ a diffuser to provide even lighting from an uneven source.

Backlights come in many colors. Monochrome LCDs typically have yellow, green, blue, or white backlights, while color displays use white backlights that cover most of the color spectrum.

Colored LED backlighting is most commonly used in small, inexpensive LCD panels. White LED backlighting is becoming dominant. ELP backlighting is often used for larger displays or when even backlighting is important; it can also be either colored or white. An ELP must be driven by relatively highAC power, which is provided by an inverter circuit. CCFL backlights are used on larger displays such as computer monitors, and are typically white in color; these also require the use of an inverter and diffuser. Incandescent backlighting was used by early LCD panels to achieve high brightness, but the limited life and excess heat produced by incandescent bulbs were severe limitations. The heat generated by incandescent bulbs typically requires the bulbs to be mounted away from the display to prevent damage.

For several years (until about 2010), the preferred backlight for matrix-addressed large LCD panels such as in monitors and TVs was based on a cold-cathode fluorescent lamp (CCFL) by using two CCFLs at opposite edges of the LCD or by an array of CCFLs behind the LCD (see picture of an array with 18 CCFLs for a 40-inch LCD TV). Due to the disadvantages in comparison with LED illumination (higher voltage and power needed, thicker panel design, no high-speed switching, faster aging), LED backlighting is becoming more popular.

LED backlighting in color screens comes in two varieties: white LED backlights and RGB LED backlights.blue LED with broad spectrum yellow phosphor to result in the emission of white light. However, because the spectral curve peaks at yellow, it is a poor match to the transmission peaks of the red and green color filters of the LCD. This causes the red and green primaries to shift toward yellow, reducing the color gamut of the display.a red, a blue, and a green LED and can be controlled to produce different color temperatures of white. RGB LEDs for backlighting are found in high end color proofing displays such as the HP DreamColor LP2480zx monitor or selected HP EliteBook notebooks, as well as more recent consumer-grade displays such as Dell"s Studio series laptops which have an optional RGB LED display.

RGB LEDs can deliver an enormous color gamut to screens.additive color) the backlight can produce a color spectrum that closely matches the color filters in the LCD pixels themselves. In this way, the filter passband can be narrowed so that each color component lets only a very narrow band of spectrum through the LCD. This improves the efficiency of the display since less light is blocked when white is displayed. Also, the actual red, green, and blue points can be moved farther out so that the display is capable of reproducing more vivid colors.

A newNanosys, claims that the color output of the dots can be tuned precisely by controlling the size of the nanocrystals. Other companies pursuing this method are Nanoco Group PLC (UK), QD Vision, 3M a licensee of Nanosys and Avantama of Switzerland.Sony has adapted Quantum Dot technology from the US company QD Visionedge-lit LED backlight marketed under the term Triluminos in 2013. With a blue LED and optimized nanocrystals for green and red colors in front of it, the resulting combined white light allows for an equivalent or better color gamut than that emitted by a more expensive set of three RGB LEDs. At the Consumer Electronics Show 2015, Samsung Electronics, LG Electronics, the Chinese TCL Corporation and Sony showed QD-enhanced LED-backlighting of LCD TVs.

CCFL backlighting has also improved in this respect. Many LCD models, from cheap TN-displays to color proofing S-IPS or S-PVA panels, have wide gamut CCFLs representing more than 95% of the NTSC color specification.

There are several challenges with LED backlights. Uniformity is hard to achieve, especially as the LEDs age, with each LED aging at a different rate. Also, the use of three separate light sources for red, green, and blue means that the white point of the display can move as the LEDs age at different rates; white LEDs are also affected by this phenomenon, with changes of several hundred kelvins being recorded. White LEDs also suffer from blue shifts at higher temperatures varying from 3141K to 3222K for 10 °C to 80 °C respectively.Benq G2420HDB consumer display has a 49W consumption compared to the 24W of the LED version of the same display (G2420HDBL).

To overcome the aforementioned challenges with RGB and white LED backlights an "advanced remote phosphor" cockpit displays,Air Traffic Control displays and medical displays. This technology uses blue pump LEDs in combination with a sheet on which phosphorous luminescent materials are printed for colour conversion. The principle is similar to Quantum Dots, but the phosphors applied are much more robust than the quantum dot nano-particles for applications that require long lifetime in more demanding operational conditions. Because the phosphor sheet is placed at a distance (remote) of the LED it experiences much less temperature stress than phosphors in white LEDs. As a result, the white point is less dependent on individual LEDs, and degrading of individual LEDs over lifetime, leading to a more homogenous backlight with improved colour consistency and lower lumen depreciation.

The use of LED backlights in notebook computers has been growing. Sony has used LED backlights in some of its higher-end slim VAIO notebooks since 2005, and Fujitsu introduced notebooks with LED backlights in 2006. In 2007, Asus, Dell, and Apple introduced LED backlights into some of their notebook models. As of 2008Lenovo has also announced LED-backlit notebooks. In October 2008, Apple announced that it would be using LED backlights for all of its notebooks and new 24-inch Apple Cinema Display, and one year later it introduced a new LED iMac, meaning all of Apple"s new computer screens are now LED. Almost every laptop with a 16:9 display introduced since September 2009 uses LED-backlit panels. This is also the case for most LCD television sets, which are marketed in some countries under the misleading name LED TV, although the image is still generated by an LCD panel.

Most LED backlights for LCDs are edge-lit, i.e. several LEDs are placed at the edges of a lightguide (Light guide plate, LGP), which distributes the light behind the LC panel. Advantages of this technique are the very thin flat-panel construction and low cost. A more expensive version is called full-array or direct LED and consists of many LEDs placed behind the LC panel (an array of LEDs), such that large panels can be evenly illuminated. This arrangement allows for local dimming to obtain darker black pixels depending on the image displayed.

Using PWM (pulse-width modulation, a technology where the intensity of the LEDs are kept constant, but the brightness adjustment is achieved by varying a time interval of flashing these constant light intensity light sources

If the frequency of the pulse-width modulation is too low or the user is very sensitive to flicker, this may cause discomfort and eye-strain, similar to the flicker of CRT displays.

For a non-ELP backlight to produce even lighting, which is critical for displays, the light is first passed through a lightguide (Light guide plate, LGP) - a specially designed layer of plastic that diffuses the light through a series of unevenly spaced bumps. The density of bumps increases further away from the light source according to a diffusion equation. The diffused light then travels to either side of the diffuser; the front faces the actual LCD panel, the back has a reflector to guide otherwise wasted light back toward the LCD panel. The reflector is sometimes made of aluminum foil or a simple white-pigmented surface.

The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman),

The evolution of energy standards and the increasing public expectations regarding power consumption have made it necessary for backlight systems to manage their power. As for other consumer electronics products (e.g., fridges or light bulbs), energy consumption categories are enforced for television sets.

Illuminating Arrangement for a Field-Effect Liquid-Crystal Display as well as Fabrication and Application of the Illuminating Arrangement, filed Oct. 15, 1976.

"First-Hand Histories: Liquid Crystal Display Evolution - Swiss Contributions". Engineering and Technology History Wiki. Archived from the original on July 3, 2017. Retrieved June 30, 2017.

Competing display technologies for the best image performance; A.J.S.M. de Vaan; Journal of the society of information displays, Volume 15, Issue 9 September 2007 Pages 657–666; http://onlinelibrary.wiley.com/doi/10.1889/1.2785199/abstract?

LED TVs: 10 things you need to know; David Carnoy, David Katzmaier; CNET.com/news; 3 June 2010; "LED TVs: 10 things you need to know". Archived from the original on 2017-12-01. Retrieved 2017-11-22.

Method of and device for generating an image having a desired brightness; D.A. Stanton; M.V.C. Stroomer; A.J.S.M. de Vaan; US patent USRE42428E; 7 June 2011; https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=RE42428E

LED local dimming explained; G. Morrison; CNET.com/news; 26 march 2016; "LED local dimming explained". Archived from the original on 2017-11-23. Retrieved 2017-11-20.

Dimming options for LCD brightness; J. Moronski; Electronicproducts.com; 3 Januari 2004; "Dimming options for LCD brightness control". March 2004. Archived from the original on 2017-07-28. Retrieved 2017-11-20.

Brochure 3M Display Materials & Systems Division Solutions for Large Displays: The right look matters; "Archived copy" (PDF). Archived (PDF) from the original on 2017-08-02. Retrieved 2017-11-20.link)

Broadband reflective polarizers based on form birefringence for ultra-thin liquid crystal displays; S.U. Pan; L. Tan and H.S. Kwok; Vol. 25, No. 15; 24 Jul 2017; Optics Express 17499; https://www.osapublishing.org/oe/viewmedia.cfm?uri=oe-25-15-17499&seq=0

Polarisation-sensitive beam splitter; D.J. Broer; A.J.S.M. de Vaan; J. Brambring; European patent EP0428213B1; 27 July 1994; https://worldwide.espacenet.com/publicationDetails/biblio?CC=EP&NR=0428213B1&KC=B1&FT=D#

Energy Efficiency Success Story: TV Energy Consumption Shrinks as Screen Size and Performance Grow, Finds New CTA Study; Consumer Technology Association; press release 12 July 2017;

LCD Television Power Draw Trends from 2003 to 2015; B. Urban and K. Roth; Fraunhofer USA Center for Sustainable Energy Systems; Final Report to the Consumer Technology Association; May 2017; "Archived copy" (PDF). Archived from the original (PDF) on 2017-08-01. Retrieved 2017-11-20.link)

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Controlling Power Consumption for Displays With Backlight Dimming; Claire Mantel et al; Journal of Display Technology; Volume: 9, Issue: 12, Dec. 2013; Mantel, Claire; Burini, Nino; Nadernejad, Ehsan; Korhonen, Jari; Forchhammer, Soren; Pedersen, Jesper Meldgaard (2013). "Controlling Power Consumption for Displays with Backlight Dimming". Journal of Display Technology. 9 (12): 933–941. Bibcode:2013JDisT...9..933M. doi:10.1109/JDT.2013.2260131. S2CID 24082090.

Select the Networkicon on the right side of the taskbar, and then move the Brightnessslider to adjust the brightness. (If the slider isn"t there, see the Notes section below.)

Some PCs can let Windows automatically adjust screen brightness based on the current lighting conditions. To find out if your PC supports this, select  Settings >System>Display. Select Brightness, look for theChange brightness automatically when lighting changes check box, and then select it to use this feature. This automatic setting helps make sure your screen is readable wherever you go. Even if you use it, you can still move theBrightness slider to fine-tune the brightness level for a built-in display.

You might also see another check box displayed: Help improve battery by optimizing the content shown and brightness. Some Windows PCs can automatically adjust the screen brightness and contrast based on content that’s displayed on your built-in screen. For more info, see Adaptive brightness and contrast in Windows.

You might not see the Brightness slider on desktop PCs that have an external monitor. To change the brightness on an external monitor, use the buttons on it.

If you don"t have a desktop PC and the slider doesn"t appear or work, try updating the display driver. Select Search on the taskbar, type Device Manager, and then select Device Manager from the list of results. In Device Manager, select Display adapters, then select the display adapter. Press and hold (or right-click) the display adapter name, then select Update driver and follow the instructions.

The LCD bias voltage that effects the LCD contrast, also effects the bias angle of the display (). So at what angle you view the display will influence the setting of the LCD bias voltage. Adjusting the contrast voltage, V , will effect the bias angle to some extent, but not the viewing angle. A 12:00 display can be optimized for a 6:00 viewing position by adjusting the contrast voltage. A 12:00 display set for 6:00 viewing position will not have as great a contrast as a 6:00 display set for 6:00 viewing

position, and vice versa. Designers often want a display to be optimized for straight-on viewing. Either a 12:00 or a 6:00 module can be used; and the contrast voltage can be adjusted slightly to optimize the display for that viewing position. Once the viewing position has been established for a design, the contrast setting can be determined. This is normally done during product development on the prototype unit. A potentiometer is connected between the appropriate power supply rails (Vdd and Vss for single supply, and Vee and Vdd for higher voltage LCD modules). The wiper of the pot is connected to Vo (LCD bias voltage input, see below). The LCD is then positioned at the nominal viewing position, and the pot is adjusted to obtain the desired LCD appearance. Depending on the optimum contrast requirement, and the ability to use more than one vendors LCD module, you can either leave the potentiometer in the design, or measure the voltage on the Vo pin and select a pair of resistors to produce this voltage in the production unit