The difference and purchase guide of side-emitting and straight-emitting LED panel lights

The design of LED panel light is beautiful and simple, luxurious and luxurious. With its good uniformity of illumination, uniform and soft light, and comfortable lighting effect, it can effectively relieve eye fatigue. It is widely used in offices, schools, hospitals, shopping malls, homes and other places. It is LED The best product of the times to replace traditional fluorescent tubes and grille lamp panels.

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

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

One is a small-size panel light, which has the same function as a downlight. The light-emitting principle is also that the light emitted by the side lamp bead conducts light from the light guide plate. There are also two types, square and round, with sizes ranging from 90mm to 225mm (diameter or side length). You can choose 3W, 6W, 9W, 12W, 15W, 18W, 24W and other different powers according to the application scenarios.

The second type is non-standard size, which is generally customized according to the customer's specific project and special size parameter requirements.

There is also a conventional size, with 300*300mm, 300*600mm, 600*600mm, 300*1200mm, 600*1200mm, and some countries and regions have slight differences in the size. For example, the size of 60*60 panel lights in China is generally 595*595mm, most of the size in Europe is also 595*595mm, Ecuador is 600*600mm, North America is 603*603mm, Germany and Brazil 620*620mm, etc.

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

Straight light panel light product structure

Straight light panel light product structure

The light of the LED lamp bead enters the light guide plate from the light-emitting surface, and then shoots downwards after reaching the reflective point of the light guide plate, and irradiates from the light-emitting surface of the lamp. The light that does not hit the reflective point will be reflected back through the reflective film, so that the LED Most of the light from the lamp beads is converted into the 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

Schematic diagram of side-emitting panel light

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

Straight light panel light product structure

Straight light panel light product structure

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

Schematic diagram of direct lighting panel light

Schematic diagram of direct lighting panel light

The frame is an important part of the panel light, and the high-strength frame makes the panel light more durable. The side frames of LED panel lights use different materials, and their heat dissipation performance is also different. The current frame materials of panel lights mainly include aluminum alloy, steel, PC, A6063, aluminum plastic, steel and other materials.

The most commonly used is aluminum frame (small panel light, useful plastic shell), which is divided into splicing and welding frames. The welding frame will be stronger and the price will be more expensive than the splicing frame. Generally, there are 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.

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), the price of the brand lamp beads will be more expensive. Because of the direct-lit panel light whose lamp beads are scattered by the optical lens, the number of lamp beads generally required is much lower than that of the side-emitting panel lamp.

The function of the diffuser plate is to evenly diffuse the light of the light guide plate, and can also play the role of blurring the dots. The materials used mainly include PC (polycarbonate plastic), acrylic, PS (polystyrene plastic), PP ( Polypropylene plastic) and so on. The price is from high to low, and PS and PP are more used.

Acrylic has a light transmittance of 92%, PC is 88%, and PS is about 80%. Acrylic material has higher light transmittance than PC, and has a lower cost, and its anti-aging performance is weak; while PC material is expensive, but anti-aging Strong performance. In addition, the thickness of the diffuser used by different manufacturers is different, and the more conventional one is 0.8mm-1.2mm thick and the price is higher. Direct-emitting panel lights have higher requirements for the intensity of the diffuser than side-emitting panel lights, and they are generally thicker.

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 transmission plate into the direction perpendicular to the light transmission 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 necessary to reduce the light attenuation as much as possible. Generally speaking, the light efficiency of the light guide plate depends largely on the dot design, followed by the choice of the plate (transmittance). Commonly used plates are PMMA (acrylic), MAS, PS, and the prices are from high to low.

PS and MAS will produce yellowing after using for a long time. PS will look like two years, and MAS will look like three years longer, depending on the climate in the area, generally speaking, it will be produced in hotter places. The yellowing time will be shorter. If you need 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, the thicker the higher the price.

Comparison of yellowing conditions under test environment (accelerated aging)

Comparison of yellowing conditions under test environment (accelerated aging)

The iron back cover is commonly used, with different thicknesses and different strengths. Compared with the side-emitting panel lights, the direct-lit panel light has a different style, the back cover is thicker, and the direct-lit back cover will be sprayed, in addition to coloring, in order to better reflect the light.

According to brand, voltage, isolation (isolation is safer), non-isolation, whether there is stroboscopic (which will affect whether the light of the lamp is taken under the mobile phone, whether there is stroboscopic), functional requirements (such as: dimming and color adjustment) and certification requirements Prices will vary.

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

Spring buckle hoisting parts and exposed frames are generally selected according to the needs of different customers.

The side-emitting panel light has the advantages of beautiful and simple, luxurious atmosphere, uniform and soft light, ultra-thin thickness, convenient installation and transportation; the disadvantage is that it is not easy to achieve high luminous efficiency, and the current cost is about 120lm/w. In addition, the light guide panel panel lights of PS and MAS have been used for a long time, and they 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 lamp will basically not turn yellow. The price has advantages compared with side-emitting; the disadvantage is that the lamp body is relatively thick, and it seems that there is no high-end side-emitting panel lamp. Box volume and freight will increase. Because of the hollow structure, compared with the side-emitting panel lights, the transportation requirements are higher. Some direct-lit panel lights will have some dark areas at the edge of the frame, mainly in the style of the beveled back cover. At present, a straight-down panel light with a right-angle edge style has appeared. There is no dark area and the light uniformity is better.

In order to meet different needs, LED panel lights have been given more functions or combined with other elements to form new products. For example, it is suitable for IP65 waterproof panel lights in environments with waterproof requirements; RGB panel lights that can change the color to adjust the atmosphere; blue sky and white cloud panel lights for hospitals to adjust mood and sterilization panel lights for purifying the environment; the combination of security and panel lights, smoke , Gas alarm panel lights; currently popular educational lighting fixtures are also extended panel lights, which are suitable for schools and help students protect their eyes; and skirting lights that combine the side-emitting principle with skirting.

Conclusion: LED side-emitting panel lights and direct-type panel lights have their own advantages and disadvantages. They have good uniformity of illumination, 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. They are widely used lamps.