How To Choose The Connection Method Of The Backlight?
Apr 11, 2022
The backlight of the segment LCD screen can be divided into three types according to the connection method: in-line light, SMD light, and light guide plate without light. Among them, SMD light can be subdivided into SMD red and black lines, SMD soft Metal feet, patch toothpick board. Today, I will share with you the advantages and disadvantages of each method.
First of all, the in-line lamp is a very simple process. To put it bluntly, it is a light-emitting diode fixed to the position of the backlight head film with glue, so the price is relatively cheap. For the backlight with only one lamp or two lamps, you can choose to do it. Plug in lights. Disadvantages: 1. Because the lamp beads of the in-line lamp are larger, the lamp eye is larger, so the head film is generally made more than 7MM, which is a headache for friends who have limited space on the circuit board; 2. The solder joints of the in-line plug More, one lamp bead corresponds to 2 solder joints, if the number of lamp beads is large, the cost of making in-line lamps will be very high.
Secondly, SMD lights, as mentioned above, can be divided into three types: red and black lines, soft metal feet, and toothpick boards. The SMD light is to stick the lamp beads on a small piece of PCB, and then clip it into the light guide plate. Because it is a SMD packaged lamp bead, it is called a SMD light. The biggest advantage of the patch lamp is that no matter how many lamp beads there are, there are only two positive and negative pins.
The connection method of the red and black lines is more flexible. For the limited space of the PCB, the components can be bypassed and the solder joints can be selected, and the outer layers of the two lines are wrapped with insulating materials, so that there will be no short circuit. Disadvantage: During transportation or processing, the red and black leads are easy to fall off.
The connection method of soft metal feet is similar to the connection of red and black wires. The position of the solder joints is not high, and the shape of the pins can be bent according to the needs. Disadvantages: 1. The pins are easy to fall off. Of course, the connection between the red and black wires is relatively firm. 2. The size of small PCB solder joints on the light guide plate is not easy to control, and there may be batches of large solder joints and small solder joints. If the solder joints are too large, it may cause the backlight solder joints on the circuit board to be covered by the backlight head film during production and processing, and the backlight pins cannot be soldered.
The connection method of the toothpick board is relatively less used. The two leads of the positive and negative poles are made together with the small PCB attached to the lamp bead, and they are fixed to death, so there will be no pins falling off in the above two ways. And if the backlight is on both sides, the spacing between the pins on the left and right sides is very accurate. Disadvantages: 1. Because the pin spacing on the left and right sides is very accurate, once the distance between the left and right solder joints on the circuit board is incorrectly designed, the backlight cannot be used; 2. The minimum order quantity of this backlight is required, generally at least 2K minimum order.
Finally, let’s talk about the next special method. This kind of backlight does not need to install lamps. Leave the lamp eye position, V groove and lamp beads on the position of the light guide plate head film. Users can use side-emitting SMD lamp beads to stick them on circuit board. The backlight of this method is very cheap. The disadvantage is that it cannot be directly fixed on the circuit board, and it needs to be fixed with double-sided tape behind the backlight.
