Edge Lit And Direct Lit Backlight Configurations

All LEDs are simply LCDs with LED backlights. These backlights provide illumination so images can be created on the LCD.

Previously, cold-cathode florescent lamps (CCFL) backlights were used, but most manufacturers have completely switched to LEDs now. The latter are more energy efficient and almost as affordable as CCFL LCDs.

Multiple arrangements are possible using LED backlights, and these arrangements may have a dramatic effect on the quality of image created. Most of the LCD models available in the market today are either edge lit or direct lit LEDs.

Edge lit LCDs

In this arrangement, LEDs are used as a row of light emitters along one or more edges, with reflective films and coatings funneling their light across the back of the LCD panel. This way, a uniform pattern is achieved.

LEDs typically used are white ones. Each manufacturer has their own preferred method of edge lit backlighting; however, different models from the same manufacturer may use different methods.

Typically, fewer LEDs will result in a less costly screen. It will also make them more energy efficient. Since, LED LCDs are already highly efficient, using fewer LEDs makes little difference.

Advantages

· It creates an overall thin display. LCD panels that are very thin most likely have LED backlighting.

· It costs considerably less since fewer LEDs are used to cover a larger display area.

Direct lit LCDs

Direct lit configurations have LEDs placed behind the LCD display instead of the edges. There are many ways in which this can be done. Most common implementation is to use arrays of LEDs in zones. Each zone can be independently controlled based on the content.

Advantages

· Much better brightness uniformity achieved through ‘zones’ of LEDs.

· Local dimming can be applied to achieve higher contrast while reducing power consumption. Backlights are turned down in a zone where the content is dark and turned up where it’s bright. Depending on the content, the LCD display can be lower power or higher depending on the brightness of the content.

· There are no size limitations; it can be used easily for very large displays.

The best LCDs in the market are ones that use the right configuration for the display size and intended application. You can find both LED and CCFL LCDs with REVO Interactive, well-known supplier of industrial LCD panels.

Their LCD panels and kits are available in various sizes and resolutions, including sunlight readable and panoramic LCD panels. Contact them today for orders and further information.

Are Resistive Touch Panels Better For Certain Applications?

Take a look around you; virtually every device now has touchscreen displays¾from consumer electronics like mobile phones and tablets to large panoramic displays used for commercial applications.

This ubiquitous adoption of touch-enabled screens has resulted in pricing and designing challenges. Several OEMs are looking for options to help drive down the costs, so as to maintain competitive pricing for the end-user.

During this process, the advantages of PCAP touch-screens were discovered. PCAP panels have enabled us to improve durability, reliability and performance of the touchscreen.

However, there are some situations where PCPA may not be the ideal technology. In these cases, our old tried and trusted resistive touch panels are preferred.

• Cost is one of the major problems. Screen size, ruggedness, unit volume and other factors impact the overall cost of a display. It’s difficult to compare the overall cost for PCAP and resistive touch solutions.
• Simply put, a PCAP sensor and controller combined costs a lot more than a resistive sensor and controller. Resistive touch is a better option if cost is a major consideration, unless PCAP features are absolutely necessary.
• Volume can impact the overall cost per unit. ITO sensors are custom designed and unique algorithm is required for tuning of PCAP controllers.
• For consumer electronics, the cost is driven down because of high production volumes. In contrast, lower volumes of industrial applications may make the costs prohibitive.
• Again, simplicity of resistive designs can be an advantage.  
•  Gloved operation isn’t feasible with PCPA panels. Some medical and industrial applications require use of rubber or leather gloves which can affect the capacitance of the touch. Most often touch function won’t work on PCAP screens. Yet, gloves have no influence whatsoever on resistive screen.
• Impact resistance requires use of a 1–2mm glass overlay, in order to protect the LCD panel and the ITO controller. For industrial and commercial applications, much higher resistance is required. They use thick 4–5 mm glass that can impact a sensor’s capacitance. Resistive panels are less sensitive, and in some cases, preferable for heavy-duty applications.
• Liquids can alter the capacitance experienced by the sensor. Industrial applications require both water rejection (rejecting false touches if liquid is present on screen) and wet finger tracking (accurately tracking the touch in presence of liquid) are necessary. This can add extra cost.

While resistive touch may be a better option in technical terms for the above-listed applications, we can’t ignore the fact that PCAP panels are more efficient. Ultimately, your decision depends on factors such as cost and quality of display.

In most cases, the end-application will help you decide between resistive and PCAP LCD touchscreen display panels. Irrespective of the technology, you can find a number of industrial LCD panels at REVO Interactive.

Browse their products today and contact them for pricing here.