Heating control of thermal print head _ printing equipment

About 2 inches of the print head, transverse has 384 plus hot; For 3 'there are 576 plus hot spots. To add hot control be abstracted a cache writes in pairs. Print head inside a cache, the cache with a bit indicates a hot whether heating. So before heating, we need to put the points in the data that will be printed immediately written to the printer by serial buffer. How to write data will not go into here, we assume that the data is written to the cache. At present, to be clear, the data must be written as soon as possible at the start of motor rotates, usually in the start of the first phase, electric will write data at the same time. After the data is written to the cache, not simply by giving a plus hotline and can realize heating power. Tested, about 3 inches of the print head, 576 points at the same time heating will make the current peak reached 11. A, most of the lithium battery can withstand current only about 6 a, a heating power lost is likely to cause the battery to be protected. All the print head will add hot into several groups control respectively. Therefore, at a certain moment, we can only to certain groups of heating. Grouping heating principle is to reduce the instantaneous current ( Reduce some time at the same time heating points) At the same time, also can ensure each basic uniform heating. Due to the limitation of portable printer problems, such as volume, cost, generally there is no constant current power supply device for the print head, so uneven group will lead to the same line in handwriting two-tone. This requires a lot of testing to determine.