What is the difference between side-emitting and direct-emitting LED panel lights? Detailed comparative evaluation of two panel lights

The LED panel light has a beautiful and simple design, luxurious atmosphere and good illumination uniformity, uniform and soft light, and comfortable lighting effect, which can effectively relieve eye fatigue. It is widely used in offices, schools, hospitals, shopping malls, homes and other places. The best product of the era to replace traditional grille light panels.

There are two types of LED panel lights: side lighting and direct lighting (direct lighting), both of which need to be used with a driving power supply.

The installation methods include embedded, surface mounted, hoisting, and integrated ceiling installation.

One is the regular size, there are 300*300mm, 300*600mm, 600*600mm, 300*1200mm, 600*1200mm, the size of some countries and regions will be slightly different. For example, the size of a 60*60 panel light is generally 595*595mm in China, 595*595mm in most of Europe, 600*600mm in Ecuador, 603*603mm in North America, and 620*620mm in Germany and Brazil.

Product structure

LED side-emitting panel light mechanism and light-emitting principle:

The structure of side-emitting LED panel light mainly includes frame, diffuser plate, light guide plate, light bar, reflective film, back plate and other components.

The light of the LED lamp bead enters the interior of the light guide plate from the light-emitting surface, and the light hits the reflective point of the light guide plate and then exits downward, and is irradiated from the light-emitting surface of the lamp. The light that does not reach the reflective point will be reflected back through the reflective film, so that the LED Most of the light from the lamp bead is converted into light used for lighting. The quality of the light guide plate is an important criterion to measure the quality of the side-emitting panel light.

Schematic diagram of side-emitting panel light

LED direct-type panel light structure and light-emitting principle:

The structure of the direct type (direct light) panel light mainly includes the frame, the diffuser plate, the light bar (including the aluminum substrate, the lamp beads, the lens) back cover

The light of the LED lamp bead is diffused by the lens and reflected from the back cover and emitted from the light-emitting surface of the lamp

Schematic diagram of direct down panel light

Analysis of various components of conventional panel lights

1. Frame: The strength of the frame affects the durability and the overall texture of the lamp

The frame is an important part of the panel light, and the high-strength frame makes the panel light more durable. The side frame of the LED panel light is made of different materials, and its heat dissipation performance is also different. At present, the frame materials of panel lights mainly include aluminum alloy, steel, PC, A6063, aluminum-plastic, steel and other materials. The most commonly used is the aluminum frame (small panel light, with a plastic shell), and it is divided into splicing and welding frames. The welding frame will be stronger and the price will be more expensive than the splicing frame. The general frame has flat frame and step frame according to the style, and the price will be different. In addition, the weight of the frame (the amount of materials used) will also affect the price.

2. Lamp beads

The type, brand and quantity of lamp beads will affect the effect of light, and the luminous flux will also affect the price. The commonly used lamp beads are SMD2835 and SMD4014, the brands are HONGLI, SANAN, SUMSANG, Lumileds (formerly Philips), and the price of the brand lamp beads will be more expensive. The direct-lit panel light generally needs far fewer lamp beads than the side-emitting panel light because the light-emitting of the lamp beads is scattered by the optical lens.

3. Diffuser plate: different materials have different light transmittance

The function of the diffuser plate is to evenly disperse the light of the light guide plate, and it can also play the role of blurring the dots. The materials used are mainly PC, acrylic, PS, PP, etc. The price is from high to low, and PS and PP are used more.

The light transmittance of acrylic is 92%, that of PC is 88%, and that of PS is about 80%. The light transmittance of acrylic material is higher than that of PC, and the cost is lower, and its anti-aging performance is weak; while PC material is expensive, but anti-aging Strong performance. In addition, the thickness of the diffuser plates used by different manufacturers is different, and the more conventional ones with a thickness of 0.8mm-1.2mm are more expensive. The direct light emitting panel light has higher requirements on the intensity of the diffuser than the side light emitting panel light, and is generally thicker.

4. Light guide plate: The plate is a factor that has a great influence on the light efficiency in addition to the lamp beads

The light guide plate is a component of the side-emitting panel light. The function of the light guide plate is to refract the light parallel to the direction of the light-transmitting plate into the direction perpendicular to the light-transmitting plate, and the light guide plate is refracted to the back of the panel light by the reflective paper. reflected. In this process, it is also necessary to reduce the light decay as much as possible. Generally speaking, the light efficiency of the light guide plate depends largely on the design of the dots, followed by the choice of the plate (light transmittance). Commonly used sheets are PMMA (acrylic), MAS, PS. Prices from high to low. PS and MAS will turn yellow after being used for a long time. PS will probably last for two years, and MAS will last for three years. It also depends on the climate of the area. Generally speaking, it is hotter in places. The resulting yellowing will take less time. If you want a 5-year warranty or higher light efficiency, PMMA light guide plates are basically used. The size of the light guide plate used by various factories is generally in the range of 1.6-3.0mm, and the thicker the price, the higher the price.

Comparison of yellowing conditions under test environment (accelerated aging)

5. Back cover

The most commonly used is the iron back cover, the thickness and weight are different, and the strength is different. Compared with the side-emitting panel light, the direct-lit panel light has a different style, the back cover is thicker, and the direct-type back cover will be spray-coated, in addition to coloring for better reflection.

6. Drive power

According to the brand, voltage, isolation (isolation is safer), non-isolation, whether there is stroboscopic (it will affect whether the light of the lamp is stroboscopic when taking pictures under the mobile phone), functional requirements (such as: dimming and color matching) and certification requirements price There will be differences.

7. PET prism sheet

Anti-glare is required (UGR<19 is not dazzling), and a prism plate or anti-glare film needs to be added before the diffuser plate.

8. Mounting accessories

The spring clip hoisting parts and the exposed frame are generally selected according to the needs of different customers.

Advantages and disadvantages of direct lighting and side lighting

The side-emitting panel light has the advantages of beautiful and concise, luxurious atmosphere, uniform and soft light emission, ultra-thin thickness, convenient installation and transportation; In addition, the light guide panel panel light using PS and MAS has been used for a long time, and it may turn yellow.

The advantage of the direct-emitting panel light is that the technology and process are relatively simple, and the semi-automatic production line makes the labor cost lower. The brightness is sufficient and it is easy to achieve high luminous efficiency. At present, it can achieve 135lm/w, and the lamps will basically not turn yellow. The price has an advantage compared to the side lighting; Volume and shipping costs will increase. Because of its hollow structure, compared with side-emitting panel lights, the transportation requirements are higher, and some direct-type panel lights will have some dark areas on the edge of the frame, mainly the style of the beveled back cover. At present, there are straight-down panel lights with right-angle edge styles, which have no dark areas and better light uniformity.

Conclusion: LED side-emitting panel lights and direct-lit panel lights have their own advantages and disadvantages. They have good illuminance uniformity, uniform and soft light, and comfortable lighting effects, which can effectively relieve eye fatigue. They are used in offices, schools, hospitals, shopping malls, homes and other places, and are widely used lamps. If you are interested in our products here, please contact us (email) sales@yenhua.cn .