Table of Contents
LED sheets are popular in the LED lighting market due to their easy installation. This blog is about the classification of LED sheets and how to cut and connect LED sheets.
1. Introduction of LED Sheets
LED sheets, also known as LED light sheets, flexible LED panels, or “Light Paper”, are ultra-thin and flexible LED panel light sources that are widely used in back lighting and decorative lighting. These innovative panels consist of high-density LED chips mounted on a flexible substrate in a grid pattern. The LED sheets can be lit on and off with the help of onboard connectors. The LED sheets can be cut into individual LEDs, and can also be connected into different sizes. In total, LED sheets are cuttable and bendable. They also have uniform brightness and permit modular splicing. All of these features make them an ideal choice in applications such as back lighting of light boxes, display cabinet lighting, restaurant/mall decoration, and back lighting for high-end stone and transparent materials.
2. Features of LED Sheets
Ultra-Thin and Flexible
With a typical thickness of around 1 mm for the panel, LED sheets are flexible enough to conform to curved surfaces and fit into narrow space.
Uniform Brightness
With the design of high-density LED arrays and lens or without lens, LED sheets could eliminate dead angles and reach uniform lighting, ensuring consistent brightness across the whole panel.
Cuttable and Splicable
Pre-marked cutting points on each LED allow users to trim sheets according to their needs. Panels of the same model can be spliced in X and Y directions and cover large areas.
Convenient Installation
With built-in connectors, there is no need to solder the LED sheets. With the help of standardized drivers and controllers, the installation and adjustment of the LED sheets turns easier.
3. Classification of LED Sheets
Classify LED sheets according to color
- Static White LED Sheet: Fixed color temperature options such as 2700K, 3000K, 4000K, 6000K, etc. This type of LED sheet is widely used in general lighting or uniform back lighting.
If you want to know more about color temperature, please check the blog A Complete Guide to LED Colors and Color Temperatures or 3000k vs 3500k vs 4000k for Living Room.
- Tunable White/CCT Adjustable LED Sheet: Using dual-color (2-in-1) or dual-drive technology, these LED sheets offer adjustable color temperatures at a range from 2700K to 6500K, which can meet the needs of daylight and warm light transfer. Therefore, this type of LED sheet is suitable for occasions that need dynamic light changes, such as exhibition lighting and indoor ambiance
- RGB (Red-Green-Blue) LED Sheet: Three-color LED enables endless color combinations via dimming controllers. This LED sheet is perfect for dynamic decorations and mood lighting.
- RGBW (RGB + White) LED Sheet: A pure white chip is added to the RGB LED, which provides high CRI white light apart from the colorful effects. This LED sheet is suitable for mall window displays and exhibition areas that require both decorative and luminous functions.
- RGBWW (5-in-1: RGB + Warm White + Cold White) LED Sheet: 5-in-1 LED allows simultaneous adjustment of warm white light and cold white light via 5-channel controllers. This type of LED sheet offers more versatile color combinations, which makes it suitable for high-end light boxes and artistic installations.
Classify LED sheets according to Control Method
- Constant Current/Voltage Driven LED sheet: External controllers adjust overall brightness or color. This is a cost-effective solution for simple applications.
- Addressable LED sheet: Built-in driver IC (e.g., WS2812, UCS2904) is put in each LED or each pixel group, which enables individual pixel control and dynamic effects such as flowing water, chasing lights and waves. Special controllers are needed to control this LED sheet. These are widely used in stage lighting, advertising screens and interactive installations.
Classify LED sheets according to Optical Design
- LED sheet without lens: Exposed LED chips with a wide 120° beam angle is suitable for back lighting that requires broad illumination.
- LED sheet with lens: Micro-lenses or reflective structures are used to optimize light distribution, reduce light spots and enhance uniformity. This kind of LED sheet is suitable for high-precision back lighting such as in ultra-thin light box.
4. How to Cut LED Sheets
Preparation
Sharp scissors or a knife is important for clean cuts, which help to avoid damaging the internal circuits. Please avoid using blunt or serrated knives, which will damage the inner wire.
Soldering iron and solder (if welding is needed)are necessary. Besides, matching connectors, heat shrink tubing or silicone for sealing in humid environments also need to be prepared.
Step-by-Step Cutting Process
1. Measure and Mark: Measure and mark the size of the LED sheet according to your needs. Please pay attention to the cutting guides such as the “scissors” symbols or dashed lines on the flexible panel.
2. Cut Under Power Off: Turn off the main power supply and ensure there is no electricity going through the panel. Cut (horizontally, vertically or diagonally) along the marked lines. Cutting outside these lines will break the circuit and lead to the malfunction of the lights.
3. Sealing and Installation: Insulate the exposed copper pads after the cutting. Use heat shrink tube or silicone to keep the lights from water and dust ingress in outdoor/humid environments. Fix the panel by using 3M adhesive on the back of the LED sheet or by fixing screws at the marked “screw” positions. Please avoid sharp screws that could pierce the panel.
Below is a video through which you could find more details.
Precautions During Cutting
- Follow the Cutting Marks Strictly: Cut only at pre-labeled points (e.g., black marks or scissors icons). Cutting elsewhere will interrupt the circuit.
- Polarity and Direction: Ensure “+” and “-” terminals are matched correctly during wire connection. Some panels’ polarity is marked with symbols or arrows. Positive polar must be connected to positive polar. Negative polar is the same. Misalignment will cause failure.
- Minimum Cutting Size: Different models have different cutting units. For example, for the same 24 led×12 led panel, the onochrome panel may allow 4 led×2 led segments (36 segments, 288 LED in total), while RGB panels may only have 3 led×2 led segments (48 segments and 288 LED in total). Normally, the quantity of each cutting unit is fixed. Cutting the lights in units smaller than that will damage the circuit.
- Bending and Wiring Limitation: Flexible LED boards can be bent moderately, but they should not be folded in the opposite direction or bent too sharply. Avoid bending in the LED chip area and follow the minimum bending radius requirements given by the manufacturer. In addition, avoid connecting multiple boards in series for too long to prevent significant voltage drops. It is commonly suggested not to connect too many boards in series in a 24V system (e.g., no more than 8 boards in a single string). Also, please leave a power margin ,which means use less than 80% of the rated power.
Interface Handling After Cutting
- Connection: Many flexible LED boards have board-end slots or matching plugs. After cutting, if the segments need to be jointed, we directly plug the butt connectors provided by the manufacturer of the segments into each other. This plug-and-play method eliminates the need of soldering and is suitable for quick installation.
- Soldering: If there is no slot on board, or if a specific length of the wire is required, the copper pads should be reserved to weld the wire. Pay attention to matching polarity when welding and use the appropriate wire gauge (such as 20AWG wire is used for ≤4A load). Each cut section has a pad for users to directly weld the wire and connect segments. After the welding, insulate the exposed solder joints to improve durability. If you are interested in different wire gauge, please check this blog: 18AWG VS 20AWG VS 22AWG VS 24AWG Cable for LED Strip.
- Power re–connection: The trimmed LED sheets need to be reconnected to the power supply. Reconnect each segment to the 24V DC power supply according to the direction of the arrow or mark. The common way is to connect those segments in parallel. The “+” of all panels is connected to the positive pole of the power supply, and the “-” is connected to the negative pole of the power supply to ensure that each segment receives an equal voltage. After the connection, it is recommended to test the LED sheets with power on. The segments can be fixed and installed only when each of them can work normally.
Difference in Cutting Different Types of LED Sheets
- Static White Panels: This LED sheet has simple two-wire (positive/negative) design with larger cutting units. Follow mark lines when cutting them and take care with polarity.
- RGB Panels: In addition to the positive and negative poles, there are extra red, green and blue lines. This LED sheet usually has a common positive pole (common anode) or common cathode. When connecting segments after cutting, the three RGB lines and the common line must be connected at the same time. Incorrect connection will result in incorrect colors or no light. Due to different structures, the minimum cutting unit of the RGB board may be different from that of the single-color board (see the cutting size in the previous section). But the principle is the same, we must cut alongside the mark and match the wire correctly.
- Addressable Panels: This type of board has built-in WS281X or similar chips and each chip controls a number of LED. They can only be cut at a specified cutting point, which is usually decided by the number of LED controlled by each IC. For example, if each chip controls 3 LED, the cutting unit is a group of 3 LED and cutting a single LED will not be allowed. It is necessary to ensure that the direction of data line is correct in order to keeping the data link subsequent and uninterrupted, otherwise the LED can’t work normally.
Common Mistakes
- Off-Mark Cutting: Always cut the LED sheet alongside the dashed lines or symbols to avoid circuit damage.
- Power-on Operation: Never cut the LED sheet while they are powered to prevent electric shock or panel burnout.
- Polarity Reversal: Reverse connection of positive and negative poles will burn out the LED. Pay attention to the “+”/”-” or arrow direction marked on the panel and follow the polarity instructions strictly. If the polarity is reverse, switch the power polarity or flip the direction of the board.
- Unsealed Edges: If the cut end is not sealed by heat shrink tubing or silicone caulking in outdoor or humid environments , water may easily enter the LED sheet, cause the short-circuit and shorten the lifespan.
- Dull Tools: Blunt knives can easily flatten the copper foil layer of the LED sheet and bring about internal short circuit. Uneven force will result in rough cuts. Please choose sharp tools and cut gently.
- Skipping Testing: After cutting, turn on the low voltage power supply to test the LED sheet before reconnecting them. Make sure that each section works normally before the final installation. Skipping the test may conceal the potential dangers.
To guarantee the normal operation of the flexible LED sheet after the cut, it is necessary to cut off the power in time, cut along the marked lines and accurately connect the segments. Use appropriate tools and connection methods such as plug connection or soldering. Besides, pay attention to the direction, polarity and size of the board to avoid common problems and achieve safe and reliable installation.
5. How to Connect LED Sheets
Here we take static white LED sheet as an example to introduce precautions and different connection methods including single-wire connection, double line connection and amplifier connection.
Single-Wire Connection
The “single-wire” here actually refers to the series connection between the power supply, dimmer and multiple LED sheets, rather than a single wire in the physical sense.
The constant voltage power supply provides a stable voltage such as 12V or 24V, which is a basic requirement to drive the white light LED sheet. The LED dimmer adjusts the LED brightness by controlling the voltage or PWM (pulse width modulation) signal. Each LED sheet is connected in series through plugs or solder points, which is beneficial to the electrical continuity.
Be sure to follow the “80% power capacity” principle, which means that the total power of the LED sheet should not exceed 80% of the rated power of the power supply. For more detailed explanation, please check this blog: How to Calculate the LED Power Supply for LED Strip.
All LED light panels share the same power supply and dimmer, which is a “single-way power” connection method. This connection is suitable for scenes with large area but simple wiring requirements. Thus, this kind of connection is often used in projects such as ceiling back lights, advertising light boxes and exhibition lighting that require large-area lighting but have very limited wiring space.
Double Line Connection
Two-wire connection is an efficient, stable and flexible way to connect LED light sheets. It is especially suitable for scenes that require large-area lighting and simple installation.
The AC 100V~240V AC input is converted into direct current (DC) through a constant voltage power supply. The output port of the constant voltage power supply is connected to an LED dimmer. The dimmer can adjust the output voltage or current to control the brightness of the LED. The LED dimmer connects multiple white light LED sheets through double-line connection. Each LED light sheet is connected through a standard interface to form a string of circuits.
How to achieve a double-line connection?
A double-line connection transmits power through positive and negative wires (usually DC + and DC-). All LED sheets are connected in parallel on the two main wires so that they share the same voltage. Two wires (positive and negative) are drawn from the output of the LED dimmer. Connect the wires to the input of the first LED sheet. The output of the first LED sheet should then be connected to the input of the next LED sheet, and so on.
Advantages:
- Simplified wiring: This method will connect multiple LED sheets in parallel, lower the complexity and make installation easier.
- Stable voltage: The parallel circuit enables each LED light sheet to receive a stable voltage with consistent brightness.
- High flexibility: The number of LED sheets can be easily increased or decreased by inserting or removing the LED sheets.
- High reliability: The failure of a single LED sheet will not affect the normal operation of other LED sheets.
- Suitable for large-area lighting: This method supports multiple LED sheets connection. It is also suitable for billboards, exhibition displays and large-area indoor lighting.
Amplifier Connection
LED amplifier is a signal booster that is used to compensate the signal when the controller drives multiple LED sheets or super long distance. With the help of the amplifier, brightness and color of all LED sheets will stay the same. The amplifier needs to be connected to the output of the LED controller and a constant voltage power supply (usually 12–24V DC) to output the amplified signal to the next LED sheet. The rated power of the amplifier should be at least equal to the total power of the LED sheets.
Usually the amplifiers are used when the project is large, the total power is close to or exceeds the controller capacity, or there is a significant brightness decrease at the end. Using an amplifier can drive the LED strips in sections, maintain the PWM signal strength and avoid voltage drop as well as distortion during long-distance transmission.
Amplifier connection is an important method to extend the control range of LED sheets. With additional power supplies and signal amplifiers, more LED sheets can be controlled with consistent brightness and dimming effects. Correct choice of power supply and connection methods are key to ensuring system stability.
For more details, please check the video:
Precautions During Connection
- Voltage matching: Make sure that the output voltage of the power supply could match the rated voltage of the LED sheet. If the voltage is too high, the LED sheets will be burned out. If the voltage is too low, the LED sheet won’t be lit up normally.
- Power matching: Calculate the total power of all parallel LED sheets and select a power supply with a rated power at least 20% higher than that (the 80% usage principle). This can prevent power supply from overload and provide a certain amount of redundancy.
- Voltage drop compensation: Pay attention to voltage drop in long-distance scenes. It is suggested to power the LED sheets at both ends or parallel multiple cables to reduce voltage drop. At the same time, use copper wire with large cross section such as 16~18AWG wire and shorten the length of the connecting wire as much as possible, which can effectively reduce the voltage drop.
- Parallel connection preference: It is recommended to connect multiple LED sheets in parallel to the same power supply. Try to avoid long series connection. With parallel connection, each LED sheet directly draws power from the power supply, which can greatly reduce the voltage drop.
- Heat dissipation: After the LED sheet is installed, measurements for heat dissipation should be taken to avoid overheating and failure in the long term.
- Solid connection: The connection between the wire and the LED sheet should be firm and reliable. It is recommended to use plugs especially used for LED sheets and protect the joints by heat shrink tube or waterproof glue. Do not use ordinary plugs that will cause looseness or poor contact.
Common Mistakes
- Reverse polarity: Connecting the red wire to the negative pole or the black wire to the positive pole will lead to malfunction or damage. LED sheets usually have only two wires: red for positive and black for negative. Check the polarity repeatedly in advance and use the multimeter if necessary.
- Overload drive: Too many LED sheets are connected in series/parallel at the same time will burn the power supply or LED sheet. The quantity of one series of lights should be calculated carefully. Try to use multiple power supplies or power the LED sheets in different circuits to reduce the load.
- Overlook of voltage drop: If only single end of the LED sheet is powered during long distance, the light at the end often turns darker and the color temperature will be warm. This can be avoided by shortening the wires of power supply, thickening the cable or adding power supplies at the other end.
- Improper power supply: LED sheet needs constant voltage DC power supply. Do not use constant current source or unregulated power supply, which will cause damage to the LED lights.
- Loose connection: Isolation or poor contact at the joint will cause flickering, heating and short circuit. Use a plug or welding that matches the LED sheet to ensure the interface is firm and isolated from air.
6. Conclusion
Cutting and connecting LED sheets is not difficult. As long as you master the methods and techniques, it will be easy to make the LED sheets work efficiently and safely. Through the detailed introduction of this article, I believe you have obtained the ability to complete the cutting and connection of LED sheets independently. Hope this article will help you to accomplish your lighting projects more smoothly.