Ledrise Led Professional

LED backlighting is a popular and versatile lighting solution that can be used in various applications, from linear lighting fixtures to luminous ceilings and illuminated signs. Achieving the perfect balance of total luminous flux and individual LED visibility is crucial for successful implementation. This article delves into the essential aspects of selecting and positioning LEDs for backlighting applications, ensuring optimal performance while meeting project requirements.

Understanding the Basics of LED Backlighting

LED backlighting involves placing light-emitting diodes (LEDs) behind a diffuse cover to create uniform and visually appealing illumination. Common applications include:

1. Linear lighting fixtures: LED strips or tubes used for accent, task, or general lighting in residential or commercial spaces.
2. Luminous ceilings: Large, uniformly lit surfaces that create a sense of spaciousness and enhance the aesthetics of interiors.
3. Illuminated signs: LED backlighting is used to create vibrant and eye-catching signs for branding, advertising, or wayfinding.

LED strips and modules used for lighting fixture use, in general, multiple LEDs.

As operating a single LED generates heat, more is generated when multiple LEDs are mounted on a PCB, due to the mutual effect. As such, in the case of LED strips or modules, the junction temperature (TJ) of each LED gets higher, compared to a single light source. This leads to the decrease in the LEDs lifetime and luminous flux.

For LED strips and modules, a better thermal management is required to minimize TJ and allow a longer lifetime of the installed products. For this purpose, the LED pitch, the PCB base material and the use of aluminum profile must be taken in consideration.

Linear LED light fixtures and LED tubes also feature a cover that protects the LEDs and diffuses the light. This cover is usually made of polycarbonate (a resin) and sometimes of glass. 

The cover has a certain light transmission rate that impacts the light's luminous flux and glare. If a cover has a high transmission rate, it will minimize the depreciation rate of the lamp’s luminous flux by reducing the light diffusion. However, the light of individual LED’s can be visible, increasing the glare effect.

Below, we present an evaluation of four covers to showcase light transmission and glare.

According to the standard EN 12464 Light and lighting - Lighting of workplaces -Indoor work places, the light level recommended for office work is the range 500 - 1000 lux - depending on activity. For precision and detailed works the light level may even approach 1500 - 2000 lux. For ambient lighting the minimum illuminance is 50 ulx for walls and 30 lux for ceilings.

Recommended light levels for different types of work spaces are indicated below:

Read more about recommended lighting levels for the home in our blog article.

This article is intended as a guide for those who are considering purchasing UVC disinfection equipment in 2021. These tips should only be considered as suggestions.

Attention buyers! - There are few recognized standards for equipment designed for UVC disinfection of air and/or surfaces. As a result, there are many advertisements and promotions claiming amazing performance with little or no scientific support.

• Ask the seller for copies of scientific papers that prove that his device actually works as he claims. The scientific work(s) should show the actual reduction of a test micro-organism in the environment in which the device is intended to work. 

• Does the product have suitable built-in UV safety sensors for automatic shutdown or does safe operation depend entirely on the operator?
• Does the device comply with NIOSH, UL, IEEE and related safety standards in the country of sale?
• Does the unit emit/generate ozone? If so, does it meet NIOSH requirements. How is the ozone attenuated? (We recommend avoiding ozone equipment, as it poses a safety risk to operators, unless ozone is specifically part of the treatment process and is used in a controlled and safe manner)?
• Is the device used to disinfect medical devices? If so, is it compliant with the requirements of the regulatory body in the EU, USA or country of sale?

• If the device is a UV rod that is used to disinfect a surface (e.g. a worktop or an envelope)

The technical specifications should state the UVC irradiance at a fixed distance from the UV front of the device (e.g. 10 mW/cm² at 2 cm).

The UV dose (irradiance multiplied by exposure time in seconds) should be at least 20-40 mJ/cm² to inactivate viruses on perfectly flat and ideal surfaces (details in this article). Thus, if the irradiance at the target surface is 10 mW/cm², the exposure time should be 2-4 seconds. However, the presence of microscopic gaps on flat surfaces can inhibit disinfection, and disinfection on other materials, such as cloths, may require completely different doses. For example, disinfection of viruses on medical masks may require doses as high as 1000 mJ/cm^2. This is a subject that is currently being researched and our current understanding changes almost daily.

With any UV device, you must NOT look at the UV light or expose your hands from the UV side. UV light is a source of skin burns/cancer and can quickly damage the eyes.

Remember that UV disinfection is based on a "line of sight" between the UV lamp and the target surface. If the UV rays are shaded by texture elements on the surface, the shaded areas may receive much less UV light or no light at all. Disinfection effectiveness is therefore determined by the UV dose to which these areas are exposed.

Like any disinfection system, UVC equipment must be used properly to be safe.

They all generate different amounts of UVC light in wavelengths from 200 - 280 nm. UVC light is much more energetic than normal sunlight and can cause a severe, sunburn-like reaction on your skin and could also damage the retina of your eye when exposed.
Some devices also produce ozone as part of their cycle, others produce light and heat like an arc welder, and still others move during their cycles. In general, all disinfection devices must therefore take into account the safety of both man and machine.

These considerations should be taken into account in the operating manual, in user training and in compliance with appropriate safety regulations.