how to increase brightness of lcd display supplier

How does the song go?My future’s so bright I need to wear shadesI"ve got a job waiting for my graduationFifty thou a year, buys a lot of . . . coffee??????

This article is limited to monochrome since they perform better in direct sunlight and can still be read when the back light is off. Also, the tooling cost, if necessary, is much lower.

Swap out the transflective polarizer with a transmissive polarizer. This increases the brightness without increasing the amount of power necessary or decreasing the half-life of the LEDs. The one downside is the display will be a bit more difficult to read when the back light is off, but it is still readable.

Every monochrome display with a LED back light contains a current limiting resistor. The lower the resistor value, the higher the current draw. Hence the brighter the back light. The down side is the back light draws more power (not always good for battery powered products) and it reduces the half-life of the LED back light.

Once the design is done and your customers see the light, the good people at Masterelectronics.comcan hold your inventory so you have more time to ship shades to your customers.

There are a few techniques that can be employed to make the LED backlight brighter, but if your goal is to compete with (or against) the direct sun light, there are better methods than to increase the brightness of the backlight.

“We need the brightest LED backlight possible for our new LCD design and we need to make sure that the LCD is sunlight readable.” This is a common request and the battle begins when engineers employ such techniques as PWM (pulse width modulation), reduction or elimination of current limiting resistors and overdriving the rated power limits with the final goal to make the backlight brighter.

Emissive & non-Emissive LCD modulesEmissive displays do not require a backlight since they produce their own light; an example of this is an OLED (Organic Light-Emitting Diode). OLED’s are readable in both dark and daylight environments.Non-Emissive displays require a backlight to illuminate the LCD when used in low or no ambient lighting conditions. Character, Graphic and Segment displays fall into this category and are the subject of this article.

What is a NIT? The brightness of a backlight is measured in "nits". As a general rule, one nit = the light produced by one candle. (It"s a bit more technical than that, but the idea works out the same.)

The majority of LCD display backlights are LED (Light Emitting Diode) and in most cases require the same power that is applied to the LCD logic (the power that drives the LCD only).

LED backlights require a current limiting resistor to reduce the driving current reaching the backlight. The lower the resistor value, the brighter the backlight.

Reducing the resistor value shortens the half-life of the LED backlight. The normal half-life of a LED backlight can range from 50K hours to 70K hours, but when overdriven the half-life can drop to 20K hours or less. This may not be an issue if the product has a short lifespan or if the backlight is rarely on, such as a cell phone.

The customer needs to decide on the tradeoff between making the LED backlight brighter and a dealing with a shorter half-life.Note: Half-life of the LED is the amount of time (in hours) for the LED to become half as bright as when it was first turned on. Half-Life is not when the backlight will burn out, but when it dims to half the brightness of when it was first turned on. MTBF (Mean Time Between Failures) is the amount of time before the backlight fails.

A second option to increasing the LED brightness is to replace the Transflective polarizer with a Transmissive polarizer.Note: Each LCD contains two polarizers, the front polarizer (facing the user) is always Transmissive; the rear polarizer is selected by the user.

One disadvantage of the Transmissive polarizer is that the display is difficult to read when the backlight is off. Transmissive is not recommended for battery powered product since the backlight must always be on.

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.

Auto-dim if lights dimmed for a projector. This might be triggered by a command from a room sensor or automatically by an ambient light sensor (Autobrite+).

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.

According to the working principle of LCD, the LCD module is a device that controls the light projection intensity when they are emitted from the backlight and passing through the polarizers and LCD panel for imaging.

In another word, the brightness of the LCD is determined by the amount of light that passing through the LCD panel (the transmittance rate of the LCD), the color filter (the transmittance rate of the CF), and the brightness of the backlight.

As the below figure and table show, when the light source (CCFL/LED) on side, assuming that the CCFL is 100%, it will lose 40% when passing through the light guide plate, lose 36% through the bottom polarizer, 18% through the LCD panel, and 1% on the surface reflection. Eventually, the utilization rate of CCFL is less than 5%.

From here we can know, how to improve the utilization rate of light is significant to enhance the brightness and color performance of LCD modules, even to the industry.

Backlight unit consists of the light source and layers of optical sheets which are used to guide the light direction as well as to enhance their utilization.

1. From the light source, we can increase the brightness, quantity, and power of the lamp, but the solution needs to consume more power and increase the size of BL.

2. From the light guide plate, it has high requirements for the material and design of the light guide plate. The solution is expensive but the increment of brightness is small.

Except for the light source, the above method third and fourth is more effective and common to adjust the brightness. Therefore, we will discuss them in the following article.

In addition to the high-reflective film at the lamp tube, the reflective film under the light guide plate is also essential. It requires a special particle structure to match the printed points of the light guide plate, which can reflect light,  and make the reflected light more uniform.

With these particular reflective films, the brightness of the axis center of the LCD can be improved by nearly 30% without changing the design and mold.

As we know, LCD has a certain visual angle. When viewing the computer from the vertical direction, the brightness is relatively high; when viewing from a direction beyond the normal line, the brightness becomes low.

This meets the personal habit of laptop users. The function of prism film is to make the originally dispersed light concentrate to a certain angle around central observation so that the brightness at the axis center can be greatly increased.

By the principle of refraction and total reflection, the prism film makes the emitted light with more than 70 º reflect back and be reused, which can increase the brightness by 110% at the center of the axis.

As known, when the light passes through the bottom polarizer, there are 50% of the light is absorbed and wasted. If we use a series of BEF, we can reuse 50% of the polarized light that is originally absorbed.

As shown in the figure, the BEF allows P1 polarized light to pass through, and reflects P2 polarized light back for reuse to become P1 and P2, in the recycles, the brightness can be increased by 60%.

All in all, with the high-efficiency reflective film, prism film, and BEF together, the overall brightness can be increased by 230%. This method will need no change in design and tooling, but the cost increment of the backlight.

In different scenarios, terminals need particular brightness in order to provide a clear display to the end users. Hence, brightness is one of the common custom requirements in LCD projects.

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).

The brightness of an LCD backlight depends on a number of different variables. In order to get the best result, and optimize the lighting and display for the intended application , it’s important to understand more about each factor and how they make an impact. Let’s take a look at four of the most important keys to controlling backlight brightness with LCD lighting.

Perhaps the most obvious element is the actual amount of power supplied. This is the most straightforward and easiest way to either increase or decrease the brightness of an LCD backlight. Increasing the power to the LEDs, within the manufacturer’s allowable forward current range, increases the brightness of the lights, while decreasing power decreases brightness in the same fashion.

Even if a power source remains at a consistent strength, the efficiency of the LEDs and the system as a whole impact how bright the LCD lighting will be. By using superior components and technology, with superior efficiency, more brightness can be squeezed out of the same power source. Factors that may impact LED efficiency include the quality of the die, the chemical makeup of the LEDs, and even the color temperature of the LEDs.

Different types of LCDs offer different degrees of transmissivity, which refers to the degree that a medium allows something such as electromagnetic radiation, or in this case specifically visible light, to pass through it. LCDs may allow less than 1 percent of light to be transmitted from the backlight to the user, whereas others can result in almost no loss. Therefore, it’s essential to consider whether or not a backlight is required when selecting an LCD, and then to select an LCD with good transmissivity.

Not to be overlooked is the lightguide. The quality and efficiency of the lightguide will have a dramatic impact on the final brightness of the LCD backlight. The reason is simple enough, as it is the lightguide that directs the light from the LED to the LCD, and much can be lost along the way. Lightguides with high efficiency levels, including those with optical lens based light extraction patterns, can increase efficiency by 20 to 30 percent.

By considering these four key factors, any DIY LCD lighting project can become more successful. For more information on a full range of LED and LCD lighting products and technologies, contact us here. In addition to offering LCD backlight products, Global Lighting Technologies is a worldwide leader for developing a full range of efficient, innovative, and customized lighting solutions.

When we use LED displays, there is sometimes a problem – differentLED screen brightnesson the same LED screen, which will affect the visual experience, and weaken our promotional effect. Today, we will discuss the reasons for this phenomenon, and methods to tackle it in a quick and effective manner!

As the picture shows below, we have two obvious brightness problems here – one picture shows that the brightness of the left part is obviously different from the right part, and the other picture reveals that some LED cabinets on the screen show different brightness.

Here we list six potential reasons below, which is necessary for you to know them if you want to have the ability to deal with this problem by yourselves quickly and efficiently!

Here is the brightness adjustment interface of NovaLCT. As you can see, if you want to adjust brightness, there are two points: brightness level, and brightness information including grayscale level and contrast level.

Actually, the software arthrogram decides these two elements will have different impacts on the final brightness, meaning if you choose one of them as a priority, the final effect will also have differences.

Here is a matter that need attention: if you have already adjusted the right brightness information, please remember to click the button “save to HW”, this means the information will be sent to receiving card and stored, so you do not have to adjust the parameters again after you restart the LED display screen.

Sometimes we can solve the different LED display brightness byreading back the rcfgx filefrom the cabinet which we want to keep the same, and then send the file to the LED cabinet that we want to change.

Of course, you can send the file to all screens, which will uniform their brightness, too. However, if you lost the file, just ask your LED display supplier to offer you a new one, or you can ask Novastar engineer for help. But normally, the prior way will be more effective.

Now, maybe you have a question: why will rcfgx file influence brightness efficiency? First of all, we have to know the value of brightness efficiency is decided by our driving IC.

If we adjust one of the values of refresh rate, grayscale, or others, the values will affect the values of other elements including brightness efficiency as the ability of a driving IC islimited.

In a word, different values will have interaction with other values, that is why different values in rcfgx files will cause different brightness efficiency even the physical factors are the same such as LED module type and pixel pitch.

If there are some LED display cabinets with different firmware, we may get different LED screen brightness because different firmware will cause different output methods of receiving cards.

How does power supply influence LED display brightness? Sometimes the output is not enough, which will cause a weaker driver current for part of the LED display screen. Thus, this part may show different brightness from others.

Therefore, what are the measurements to solve it? You can go tocheck the power supply output to see whether it is correct based on the values your suppliers providing to you.

As you know, different LED module batches may be produced by different raw materials, thus, the brightness of masks, the matt effect all may have discrepancies.

a. Different brightness mode.We have two parts in this sector that will influence the final brightness effect, one is brightness level, and the other is brightness information – contrast and grayscale.

b. Different RCGFX file.As the capability of driver IC is limited, when you adjust the values of one of the elements such as grayscale and refresh rate, the final brightness brightness efficiency will be different.

That is why even physical factors of LED cabinets are the same, sometimes the brightness will have disparity. Try to replace the wrong rcgfx file with the right one to unify the whole screen brightness!

c. Different firmware.Different firmware will have different output method of receiving card. Please be notified if your screen applies customized one, it is recommended that you can turn to suppliers for the right version, and never update by yourselves directly.

e. Multiple LED module batches. Different raw materials will have different effect on LED display modules. For example, some modules will brighter than other batches even not powered on.

f. Out of sync calibration coefficient. The reasons may be that receiving cards lost its calibration coefficients, or the receiving card has been replaced, or the receiving cards don’t turn on calibration.

In this sector, I want to bring you to review some knowledge points we have learned in the previous posts. They are all important for you to become an LED display expert and will be helpful if you need to operate LED displays by yourself.

Before we finish the article today, let us review what we have learned in the last articleLED black screen. There are two situations here: whole LED screen blackout and part of the screen blackout.For each situation, we have corresponding methods to deal with.

For the full black LED display, please check the red indicator light of receiving card at first to make sure that it is powering on. If yes, go to check other points according to conditions of green indicator lights such as Ethernet cable and receiving card files.

For the part of LED screen black, there are three levels including LED module level, LED cabinet level, and output port level.The problem may come from HUB board, flat cable, power supply, Ethernet cable, and so on. Just check them under guidance.

In this article NovaLCT Screen Configuration, we talked about how to configure NovaLCT from four aspects: graphics card settings, sending card settings, receiving card settings, and screen connection.

(1) For the graphics card configuration, there are displaying modes and display settings for you to choose from. Please make sure the steps that can enable your LED display boards displayed pixel-by-pixel.

(3) For the receiving card configuration, you can load in the parameters from the rcfg file. But if you do not have such file, try to read back the parameters.

(4) For the LED display connection, please fill in the right information such as the quantity of screen, columns, and rows of receiving cards, and so on. Please notify there are two very useful functions – “Enable Mapping” and “Detect Communication Status.”

It is simple if you can follow this sequence to complete the configuration. However, there are still many details for you to notice. So, just read this article again if your memory has some blur.

In this essay, we discussed LED display color distortion – why does LED display board go cyan. The main reason are overheat, but why will the screen go cyan, but not other colors?

To explain this, we talked about output efficiency of brightness of different colors under a given temperature, and discovered one truth – the losses of the brightness of the three primaries are different, and the red light will lose the most.

Today, we talked about a common problem – different LED screen brightness, and the reasons for it, and how to solve it. We listed six potential reasons and the corresponding methods to deal with. If you can check and do it under the guidance, we believe you can deal with the brightness problem quickly and precisely! For any more useful information about LED display and LED display control systems, please turn to our LED FAQ page!

There are more and more TFT displays used in outdoor applications, such as automobile display, digital signage and kiosks. High ambient light in outdoor environment often causes wash-out image and renders the screen not readable. Readability & sustainability of TFT  display under direct sunlight is becoming vital. Topway Display has been developing sunlight readable LCD display solution for years. The company understands the ins and outs of sunlight readable TFT LCD.

For an LCD to be readable in outdoor environment with very bright ambient light, the LCD screen’s brightness needs to exceed the intensity of light that is reflected from the display surface. To be comfortably viewed by human eyes, the LCD’s brightness needs to exceed its reflected light by a factor of 2.5 at minimum. Naturally, to make an LCD sunlight readable, we can work on two areas, increasing brightness or reducing reflectance.

On a clear day in direct sunlight, the ambient brightness is about 6000 cd/m2. And a typical TFT LCD with touch screen reflects about 14% of ambient light, which is around 840 cd/m2. These days, most LCD displays use LED backlight as light source. It is not too difficult to increase an LCD’s brightness to 800 ~ 1000 Nits, to overpower the bright reflected sunlight. Thus, you have a sunlight readable TFT LCD.

However, this method requires more backlight LEDs and/or higher driving current. The drawbacks are high power consumption, more heat dissipation, increased product size and shorter LED backlight lifespan. Apparently, increasing backlight to make TFT LCD sunlight-readable is not a very good solution.

Transflective TFT LCD is a TFT LCD with both transmissive and reflective characteristics. A partially reflective mirror layer is added between LCD and backlight. This change turns part of the reflected ambient light into LCD’s light source, increasing the TFT display’s brightness. However, transflective TFT LCD is more expensive than transmissive one. At the same time, the partially reflective mirror layer will block some of the backlight, making it not ideal in indoor or low ambient light environment.

What causes light reflection? When light traveling in one transparent medium encounters a boundary with another transparent medium, a portion of the light bounces off the border. Through the simplest version of Fresnel’s equation, we can calculate the amount of reflected light.

The total reflectance on a TFT LCD with touch panel is the sum of reflected light on any interface where two materials meet. As an example, between polarizer and display glass, the difference in index of refractions for the two materials is very small, around 0.1. So the reflected light on this interface is only 0.1%. As Fresnel’s equation points out, we should focus reflection reduction on air interfaces. For air, its index of refraction is 1; for glass, it is 1.5. And that results in a reflectance of 4.5%. Therefore, the three air interfaces contribute majority of TFT LCD’s reflectance, at about 13%.

The quick and easiest thing we can do to reduce air-glass interface reflectance is to use an Anti-Reflection and Anti-Glare film or apply AR coating. An external film with AR properties not only reduces reflected light, but also brings other benefits.

For food industry application, shattered glass is a serious problem. An LCD screen with external film solves this issue nicely. As for automotive applications, in an accident, broken LCD with top AR film won’t produce sharp edge glass that could harms auto occupant. Nevertheless, a top film always reduces TFT LCD’s surface hardness. And it is susceptible to scratches. On the other hand, AR coating retains LCD’s hardness and touch performance. But it comes with a bigger price tag.

Another quick and easy way to tackle reflectance is to affix a linear polarizer on the top of TFT screen. When ambient light gets to the top polarizer, only half of the light passes through. Which results in reflection light cutting to half. This is a very low cost way to increase TFT LCD’s contrast, such that making it more sunlight readable.

Laminating a circular polarizer in TFT LCD will get rid of a lot of reflectance. That is because when ambient light passes through circular polarizer it gets circularly polarized. And when it is reflected, the polarization direction flips by 180 degrees. So when reflected light comes back to the circular polarizer, nothing goes through to viewer’s eyes.

This method is very effective for an LCD display with resistive touch panel. We know resistive touch LCD has two air gaps: air gap between two ITO layers and air gap between touch panel and LCD display. Reflectance caused by the two air gaps is very high. Applying circular polarizer blocks off most of the reflected light, and makes the LCD display sunlight readable.

The disadvantage of such solution is its cost. Since we need not only a circular polarizer, but also a retarder film on the top of LCD display, making sure light originates from within LCD is not blocked by external circular polarizer.

Add AR films on both interfaces of internal air gap. The add-ons can reduce this area’s reflection from 8.5% to 2%. And since the AR films are not outside facing, they are much cheaper than the one used outside. Keeping the air gap also retains the ease of service, in case either touch panel or LCD display needs to be repaired.

The most effective way is to eliminate air gap totally, by using optical bonding. In plain language, we fill air gap with special optical adhesive, to smooth out the area’s refraction index differences. Such that reflectance caused by internal air gap drops from 8.5% to 0.5%. Optical bonding is expensive but effective way to improve TFT LCD sunlight readability. It enhances durability and resistance to impact. Moreover, no air gap means no moisture condensation and fogging.

There are many ways to make TFT LCDsunlight readable. They all have their own pros and cons. With 20+ years" LCD design and manufacturing experience, Topway knows how to create the best sunlight readable TFT LCD for challenging environments. Leave us a message and let"s start the conversation of creating suitable sunlight readable TFT LCD for your project.

While we generally avoid going into deep detail when it comes to our display testing, in light of statements that seemingly contradict our testing it becomes important to contextualize our display tests. Many people are often confused by contradicting statements regarding the peak brightness of an AMOLED display, as we will state that the Samsung Galaxy Note 4’s display reaches a maximum of 462 cd/m^2, while other sites often state that the Note 4’s display reaches a maximum of 750 cd/m^2. Another commonly cited discrepancy is that we rate the Nexus 6’s display to reach a peak brightness of 258 nits, while others have rated the Nexus 6’s display to be as bright as 400 nits.

One might immediately assume that one measurement is right, and the other is false. In truth, both measurements are achievable, as we’ll soon see. Before we get into any discussion of testing methodology though, we must first understand how AMOLED and LCD displays work. Fundamentally, LCD and OLED displays are almost completely different from one another, but face similar issues and limitations. LCD is the older of the two technologies, and is fundamentally quite simple, although not quite as simple as OLED. In short, we can view an LCD display as made of a backlight, and a color filtering array which has liquid crystals that control the passage of light, along with polarizers to make sure that the filtering system works correctly.

To break this system down further, we can look at the backlight. In the case of mobile devices, the only acceptable backlight system for thickness and power efficiency reasons is the edge-lit LED, which places a line of LEDs along an edge of the display, which is then diffused through a sheet of transparent material with strategically-placed bumps in the material to create points of light via total internal reflection. For the most part, LEDs in use today are blue LEDs with yellow phosphors in order to increase efficiency, although this means that the natural white point of such a backlight is higher than 6504k and requires filtering in order to reach a calibrated white point.

While the backlight is relatively simple, the actual color filtering is a bit more complicated, although we will avoid extensive depth in this case. In the case of IPS, the structure is generally quite simple in nature, with two electrodes in plane with each other, which is used to generate an electric field that rotates the orientation of the liquid crystals in plane with the display to dynamically alter the polarization of the light that can pass through the liquid crystal array. With a set of fixed polarizers before and after the liquid crystal array, by using the controlling TFTs to alter the voltage applied on the electrodes one can adjust individual color output on a per-pixel basis.

AMOLED is a fundamentally different approach to the problem, which uses organic emitters deposited upon a substrate. These emitters are designed to emit red, green, or blue when voltage is applied across two electrodes. Similarly, TFTs are needed to control each pixel. As one can see, AMOLED is a simpler solution, but in practice the issues with such an implementation can be quite complex.

In order to determine what picture content to use for a measurement of maximum brightness, we must turn to a measurement known as Average Picture Level (APL). This is best explained as the percentage of the display that is lit up compared to a full white display, so a display that is completely red, green, or blue would be 33% APL.

As one might already be able to guess, with AMOLED power consumption is highly dependent upon the content displayed. With a pure white image, every pixel must be lit, while with a pure black image every pixel is off. As the display typically has a maximum power use set for a mobile device, this opens up the capability for AMOLED displays to allocate more power per pixel (i.e. higher maximum luminance) when not displaying a full-white image. This is in contrast with the edge-lit LCDs used in mobile displays, which have relatively limited local-dimming capabilities. As a result, the maximum brightness of an LCD is relatively fixed, regardless of the displayed content.

In the case of the Nexus 6, we can clearly see dimishing returns after 40% APL as there is efficiency droop on AMOLED displays that are similar in nature to LED backlights. While now it’s easy to understand why it is that AMOLED can vary in maximum brightness, the question is which brightness is “correct”. While an AMOLED display can technically have a maximum brightness of 750 nits, it’s unlikely that people will look at images effectively equivalent to 1% of the display lit up with white.

In practice, it turns out that with Lollipop and almost all web pages, the average picture level is quite high. It’s increasingly rare to see cases where displayed content is below 50% APL. According to Motorola, 80% APL represents an average APL for light UIs and in light of this, it seems appropriate to test at similarly real-world APLs. Taking a look at some commonly used applications in Lollipop, we see that the APL is regularly at or above even Motorola"s 80% figure. I opened some of the applications on my Nexus 6"s homescreen to take screenshots of whatever they had open when they came up, and I"ve tabulated the results below.

As you can see, many of the screens in Android"s interface as well as web pages and third party apps have a high APL. There are exceptions, like the Calculator application and any application with a dark theme, but the overall trend is clear. Google"s new interface style also means that applications are more likely to adopt interfaces with large amounts of white than in the past.

As a result of this, we test at 100% APL in order to get an idea of perceived brightness. While there may be some need for lower APL testing, it’s important to also consider cases such as OLED aging which will lower peak brightness over time. It"s also important to consider that the delta between 80% APL and 100% APL in this case is around 44 nits. This makes for about an 18% delta in brightness, which ends up being around the noticeable difference in most cases. While our testing is subject to change, in the case of brightness we currently do not see much need to dramatically alter our methodology.

If you are having difficulty reading the information displayed on the LCD, try changing the contrast setting. Adjusting the contrast will give the information a sharper and more vivid appearance.

On iPhone, you can make your screen dimmer or brighter (dimming the screen extends battery life). You can also adjust the screen brightness and color manually or automatically with Dark Mode, True Tone, and Night Shift.

Dark Mode gives the entire iPhone experience a dark color scheme that’s perfect for low-light environments. With Dark Mode on, you can use your iPhone while, for example, reading in bed, without disturbing the person next to you.

Schedule Night Shift to shift the colors in your display to the warmer end of the spectrum at night and make viewing the screen easier on your eyes.Go to Settings

The 12.9-inch Liquid Retina XDR display has an IPS LCD panel supporting a resolution of 2732 by 2048 pixels for a total of 5.6 million pixels with 264 pixels per inch. To achieve Extreme Dynamic Range required an entirely new display architecture on iPad Pro. The all new 2D mini-LED backlighting system with individually controlled local dimming zones was the best choice for delivering the extremely high full-screen brightness and contrast ratio, and off-axis color accuracy, that creative professionals depend on for their workflows.

The Liquid Retina XDR display can support up to 1000 nits of full-screen brightness. It can also support up to 1600 nits for highlights in up to 40 percent of the screen area when the rest of that image is black or at brightness up to 600 nits.

Unlike the previous design that takes light emitting from one edge of the display and evenly distributes it across the entire back, the Liquid Retina XDR display uses over 10,000 custom-designed mini-LEDs spread uniformly across the entire back of the display, delivering higher LED density than any other display of its kind. These mini-LEDs are grouped into an array of over 2,500 individually controlled local dimming zones. This delivers incredibly deep blacks right next to bright image areas, achieving a 1,000,000:1 contrast ratio.

The Liquid Retina XDR display improves upon the trade-offs of typical local dimming systems, where the extreme brightness of LEDs might cause a slight blooming effect because the LED zones are larger than the LCD pixel size. This display is designed to deliver crisp front-of-screen performance with its incredibly small custom mini-LED design, industry leading mini-LED density, large number of individually controlled local dimming zones, and custom optical films that shape the light while maintaining image fidelity and extreme brightness and contrast.

Additionally, custom algorithms run on the advanced display engine of the M1 chip, working at the pixel level to control the mini-LED and LCD layers of the display separately, treating them as two distinct displays. These proprietary algorithms coordinate the mini-LED and LCD layers across transitions to deliver the optimal visual experience. Transitional characteristics of local dimming zones, such as a slight blur or color change while scrolling against black backgrounds, are normal behavior.

The Liquid Retina XDR display delivers P3 wide color. The color gamut afforded by the P3 primaries is larger than sRGB, offering richer and more saturated colors, especially with certain reds, yellows, and greens. The result is rich and vibrant color that’s also used in the digital cinema industry. Every Liquid Retina XDR display is also calibrated at the factory for color, brightness, gamma, and white point for a consistent visual experience.

ProMotion technology automatically adjusts the display refresh rate up to 120 Hz (twice the rate of typical LCD displays) to the optimal rate for the content. The result is ultra-smooth scrolling and incredible responsiveness on the display, whether you’re using your finger or Apple Pencil. True Tone technology subtly adjusts the white balance onscreen to match the color temperature of the light around you, so images on the display look as natural as on a printed page. The cover glass on the Liquid Retina XDR display has an on-axis reflection of 1.8 percent due to a custom antireflective coating. As a result, iPad Pro delivers industry-leading reflectivity for a more comfortable viewing experience indoors and out.

To resize a LCD is literally to cut the glass, polarizers, circuits and circuit boards to a new size. Years ago, it was thought impossible to preserve the original performance of a previously manufactured LCD once the glass circuits are cut. However, Litemax has done the impossible, over and over again, becoming the world"s leading pioneer and leader in LCD resizing solutions.

Squarepixel series is designed for high brightness with power efficiency LED backlight. It provides LCD panel with specific aspect ratios and sunlight readable for digital signage, public transportation, exhibition hall, department store, and the vending machines.

The spirit of Durapixel indeed lies with its name: durability. Why Durapixel? Commercial-grade LCD displays, due to the competitive pricing structure, are unable to offer more than MTBF of 30,000 hours, which will not be sufficient for any applications that require around-the-clock operations. System designers, integrators and users serious about rugged, industrial displays for demanding environments need to look no further – the unfailingly robust and high-quality Durapixel is the key to each of your success.

UbiPixel, industrial LCDs are used in many professional applications. High bright sunlight readable and low power consumption display technologies offer the highest quality LCDs for specific industrial applications. Our embedded LCD can be manufactured in an open frame, VESA mount, or fully enclosed housing for HMI display, KIOSK, Vending machine, home automation, point-of-sale terminals, digital signage and more. UbiPixel, industrial LCDs are used in many professional applications. High bright sunlight readable and low power consumption display technologies offer the highest quality LCD screen for specific industrial applications. Our embedded LCD can be manufactured in an open frame, VESA mount or fully enclosed housing for HMI display, KIOSK, Vending machine, home automation, point-of-sale terminals, digital signage and more.

Marine displays from Litemax are internationally recognized and certified with a proven track record of satisfying all types of scenarios, applications and environments for maritime professionals and organizations. Whether the project involves system building, maintenance, repair or equipment upgrade of a yacht, a submarine or any relevant maritime structure, Litemax"s marine displays guarantee high quality and performance from the dock to the engine room.

Litemax"s 2.5” Pico-ITX boards feature fanless operation, low power, compact designed for space-limited embedded applications. With built-in AMIO expansion interface to develop high flexibility and scalable capabilities.

Litemax"s 3.5" SBCs feature rich I/O ports, wide-temperature support, and wide input voltage range and low-power to robust high -performance computing modules designed for outdoor applications or harsh environmental requirements.

Litemax"s Mini-ITX embedded board provides the performance, expansibility, and durability to meet needs across a wide variety of applications, such as industrial control, industrial IOT, gaming, smart healthcare, and digital signage.

This high performance series supports Intel, AMD, Nvidia processor with multi I/O expansions, mini PCIe/M.2 expansion cards, and wide temperature range, being ideal for automation system, machine automation, factory automation, and IoT platforms.

Featuring a modular designed, this series can be fitted with a number of modules to expand its base capabilities. On-site maintenance and future upgradability are easier than ever by deploying our panel PCs and monitors.

Litemax rugged panel PCs go beyond that of the standard industrial panel computes with elegant, full IP68/65-rated construction, powerful performance and flexible mounting options making it ideal for harsh environments and demanding applications, such as machine controller, command centers, and fast, efficient computing.

The Litemax ITRP series is fanless Passenger Information System, It features stretched LCD display, with high brightness to ensure easy readability even in light-insufficient environments. It serves as a reliable platform to provide passenger information on wide versatility of vehicles, such as bus and trams.

Litemax develops an embedded artificial intelligence application platform for AI edge computing to meet client vertical market applications and various needs and solve the changing challenges of the operating environment. In response to the increasing demand for AI computing, computer vision, deep learning, edge computing, etc., Litemax offers a series of fanless BOX PC with Intel Edge Computing and NVIDIA® Jetson Nano™ to effectively improve the cooling performance of fanless systems. Field applications can smoothly provide powerful computing performance, support high-level AI computing chips, and provide a solution platform for a variety of application scenarios to integrate software and hardware to create more flexible and better vertical functions. Simplify the manpower required for the client to invest in AI system integration.

Intel® offers the Intel® Smart Display Module (Intel® SDM) specification and reference design that can be integrated into the sleekest all-in-one designs. Intel® SDM delivers the same level of intelligence and interoperability as the Open Pluggable Specification, but in our smallest form factor yet eliminates the housing and advances the thinnest integrated displays.

The new Intel® Smart Kiosk Module (Intel® SKM) is a revolutionary solution that makes it easier to scale and maintain interactive kiosks, which are increasingly being used by businesses and governments worldwide to offer customers around-the-clock access to information and services.As the market for interactive kiosks increases, so does the demand for smarter multi-function kiosks with advanced capabilities such as workload consolidation, artificial intelligence, smartphone and social media integration, 5G connectivity, telepresence, remote manageability, and data analytics.

LITEMAX AD Board is with high speed Analog/ Digital conversion and minimal programming. A wide variety of computer interfaces are available in your choice.

LITEMAX power board provides maximum output from 60W to 100W, it is an intelligent vehicle power converter with wide input voltage range from 9V to 16V DC.

Through intelligent thermal management technologies, Litemax is enabling smarter platforms for various vertical markets deploying display systems. Through the intelligent thermal control board, Litemax helps system integrators and engineers around the world improve efficiency and reliability.

Screen brightness might be tricky to control. On some machines physical hardware switches are missing and software solutions may not work well. However, it is generally possible to find a functional method for a given hardware. This article aims to summarize all possible ways to adjust the backlight.

There are many ways to control brightness of a monitor, laptop or integrated panel (such as the iMac). According to these discussions and this wiki page the control method can be divided into these categories:

brightness is controlled by either the ACPI, graphic or platform driver. In this case, backlight control is exposed to the user through /sys/class/backlight which can be used by user-space backlight utilities.

Note: Since OLED screens have no backlight, brightness cannot be controlled by changing backlight power on laptops equipped with an OLED screen. In this case, perceived screen brightness can be adjusted with a PWM control (not implemented in the Linux kernel) or via software color correction.

The brightness of the screen backlight is adjusted by setting the power level of the backlight LEDs or cathodes. The power level can often be controlled using the ACPI kernel module for video. An interface to this module is provided via a /sys/class/backlight/.

In this case, the backlight is managed by an ATI graphics card. In the case of an Intel card, the directory is called intel_backlight. In the following examples, acpi_video0 is used. If you use an Intel card, simply replace acpi_video0 with intel_backlight in the examples.

By default, only root can change the brightness by this method. To allow users in the video group to change the brightness, a udev rule such as the following can be used:

Reason: Explain why it is not possible to alter file permissions with GROUP="video", MODE="0664". (Discuss in Talk:Backlight#Udev rules for permissions of brightness doesn"t work)

Sometimes ACPI does not work well due to different motherboard implementations and ACPI quirks. This results in, for instance, inaccurate brightness notifications. This includes some laptops with dual graphics (e.g., Nvidia/Radeon dedicated GPU with Intel/AMD integrated GPU). Additionally, ACPI sometimes needs to register its own acpi_video0 backlight even if one already exists (such as intel_backlight), which can be done by adding one of the following kernel parameters:

Note: The systemd-backlight service restores the previous backlight brightness level at boot. To prevent conflicts for the above rules, see #Save and restore functionality.

Tip: To set the backlight depending on power state, see Power management#Using a script and an udev rule and use your favourite backlight utility in the script.

In some cases (e.g. Intel Mobile 945GME [1]), it is possible to set the register of the graphic card to adjust the backlight. It means you adjust the backlight by manipulating the hardware directly, which can be risky and generally is not a good idea. Not all of the graphic cards support this method.

DDC/CI (Display Data Channel Command Interface) can be used to communicate with external monitors implementing MCCS (Monitor Control Command Set) over I2C. DDC can control brightness, contrast, inputs, etc on supported monitors. Settings available via the OSD (On-Screen Display) panel can usually also be managed via DDC. The kernel module i2c-dev may need to be loaded if the /dev/i2c-* devices do not exist.

Users of NVIDIA"s proprietary drivers may need to add Option "RegistryDwords" "RMUseSwI2c=0x01; RMI2cSpeed=100" to the Device section in /etc/X11/xorg.conf.d/20-nvidia.conf (generated by nvidia-xconfig) or options nvidia NVreg_RegistryDwords=RMUseSwI2c=0x01;RMI2cSpeed=100 to /etc/modprobe/conf.d/nvidia.conf. Confirm that the settings are correctly applied with grep RegistryDwords /proc/driver/nvidia/params and check that the values are not empty. See [2] and [3]

ddcutil will fail to set some VCP features if there is a feature enabled on the monitor which already automatically adjusts them (e.g. Dynamic Contrast Ratio or BenQ"s Eye Care technology).

To facilitate binding screen brightness control to a keyboard shortcut, it may be convenient to enable non-superuser access to the relevant I2C devices. This can be achieved by adding a group i2c and configuring udev to set this group as the owner of the I2C devices. See [4].

If /usr/share/ddcutil/data/90-nvidia-i2c.conf file, which can be copied to /etc/X11/xorg.conf.d/ instead of manually editing Xorg configuration files. It also provides /usr/share/ddcutil/data/45-ddcutil-i2c.rules and /usr/share/ddcutil/data/45-ddcutil-usb.rules for udev rules.

Switching off the backlight (for example when one locks a notebook) can be useful to conserve battery energy. Ideally the following command should work for any Xorg graphical session:

If the previous commands do not work, there is a chance that vbetool may work. Note, however, that in this case the backlight must be manually activated again. The command is as follows:

The systemd package includes the service systemd-backlight@.service, which is enabled by default and "static". It saves the backlight brightness level at shutdown and restores it at boot. The service uses the ACPI method described in #ACPI, generating services for each folder found in /sys/class/backlight/. For example, if there is a folder named acpi_video0, it generates a service called systemd-backlight@backlight:acpi_video0.service. When using other methods of setting the backlight at boot, it is recommended to stop systemd-backlight from restoring the backlight by setting the kernel parameters parameter systemd.restore_state=0. See

Note: Some laptops have multiple video cards (e.g. Optimus) and the backlight restoration fails. Try masking an instance of the service (e.g. systemd-backlight@backlight:acpi_video1 for acpi_video1).

Note: The utilities in the following table can be used to control screen brightness. All of them are compatible with Wayland and do not require X. Some (like video (or input) group to modify brightness.

Manages screen temperature (Xorg only) and smoothly dims brightness after a timeout. Supports ambient light sensors [5]. Can turn webcam into an ambient light sensor.

Automatic brightness adjustment based on screen contents and ambient light. Can use webcam or time to simulate ambient light sensor. Supports keyboards and external monitors. Uses wlroots.

Tip: Commands involving these utilities can be bound to the XF86MonBrightnessUp and XF86MonBrightnessDown keyboard keys as described in Keyboard shortcuts#Xorg.

If you get the "No outputs have backlight property" error, it is because xrandr/xbacklight does not choose the right directory in /sys/class/backlight. You can specify the directory by setting the Backlight option of the device section in /etc/X11/xorg.conf.d/20-video.conf. For instance, if the name of the directory is intel_backlight and using the Intel driver, the device section may be configured as follows:

Note: Using this with an iGPU+dGPU setup can cause unpredictable screen update lag and/or flickering in user interface items inside apps that are offloaded to the dGPU. Only use this if all else fails.

If you have enabled Intel Fastboot you might also get the No outputs have backlight property error. In this case, trying the above method may cause Xorg to crash on start up. You should disable it to fix the issue. It is known to cause issues with brightness control.

$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.freedesktop.DBus.Properties.Set org.gnome.SettingsDaemon.Power.Screen Brightness ""

Color correction does not change the backlight power, it just modifies the video lookup table: this means that your battery life will be unaffected by the change. Nevertheless, it could be useful when no backlight control is available (desktop PCs or laptops with OLED screens).

Clight — User daemon utility that aims to fully manage your display. It can manage the screen temperature depending on the current time of the day, just like redshift does. It tries to use

Redshift does not support Wayland (without a patch or fork like AUR). But it is possible to apply the desired temperature in tty before starting a compositor. For example:

This should roughly double luma in the image. It will sacrifice color quality for brightness, nevertheless it is particularly suited for situations where the ambient light is very bright (e.g. sunlight).

This can also be used to reduce perceived brightness in a dark room by specifying some value less than 1 (e.g. 0.5), this is useful when no backlight control is available (e.g. desktop PC).

Users of NVIDIA"s proprietary drivers can change display brightness via the nvidia-settings utility under "X Server Color Correction." However, note that this has absolutely nothing to do with backlight (intensity), it merely adjusts the color output. (Reducing brightness this way is a power-inefficient last resort when all other options fail; increasing brightness spoils your color output completely, in a way similar to overexposed photos.)

Reason: Modern LED display using IPS panel usually utilize DC dimming instead of PWM dimming. This can be indicated by the two upper bytes of 0xC8254 register 0x0001, which means the frequency is almost infinity. (Discuss in Talk:Backlight)

Laptops with LED backlight are known to have screen flicker sometimes. This is because the most efficient way of controlling LED backlight brightness is by turning the LED"s on and off very quickly varying the amount of time they are on.

However, the frequency of the switching, so-called PWM (pulse-width modulation) frequency, may not be high enough for the eye to perceive it as a single brightness and instead see flickering. This causes some people to have symptoms such as headaches and eyestrain.

Period of PWM (inverse to frequency) is stored in 2 higher bytes of 0xC8254 register (if you are using the Intel GM45 chipset use address 0x61254 instead). To manipulate registers values install

Embedded Display Port (eDP) v1.2 introduced a new display panel control protocol for backlight and other controls that works through the AUX channel [7]

Note: This behavior and their workarounds have been confirmed on the Dell M6700 with Nvidia K5000m (BIOS version prior to A10) and Clevo P750ZM (Eurocom P5 Pro Extreme) with Nvidia 980m.

On some systems, the brightness hotkeys on your keyboard correctly modify the values of the acpi interface in /sys/class/backlight/acpi_video0/actual_brightness but the brightness of the screen is not changed. Brightness applets from desktop environments may also show changes to no effect.

A workaround is to use the inotify kernel api to trigger xbacklight each time the value of /sys/class/backlight/acpi_video0/actual_brightness changes.

Due to a bug introduced recently in the amdgpu driver, the backlight"s actual_brightness value is reported as a 16-bit integer, which is outside the 8-bit range specified in max_brightness. This causes the systemd-backlight service to attempt to restore, at boot time, a value that is too large and ends being truncated to maximum brightness (255).

While the bug is not addressed, one possible workaround is to modify the stored brightness to within the correct range before it is restored. This can be accomplished with a script and a service unit:

On certain systems, the backlight level reported by the driver is in the correct range [0, 255], but systemd still fails to restore the correct va