One of the most essential components in any printing job is the printhead – which type of printhead is used greatly affects the overall outcome of the project. Here’s what you need to know about different printheads and how to select the most appropriate one for your specific printing project.
Printheads are a component in all types of digital printers that are used to transfer the desired image onto your chosen print media. The printhead will spray, write, or drop the ink onto your paper in the pattern needed to produce the finished image.
The mechanism is made with a number of electrical components and multiple nozzles that will hold the different ink colors. Most often, printheads will include inks including cyan, yellow, magenta, and black with additional colors sometimes including light magenta, and light cyan.
The electrical circuits will send messages to the print nozzles signaling each one when and how much ink it needs to output. You will usually find printheads in inkjet printers, where the print head component will most often be found on the inside of the ink or printer cartridge.
When an image is sent to the printer, the printhead will receive the image information as instructions after which it will evaluate the necessary intensity, amount, and location where the ink will be required. Once the calculations are complete, the head will move horizontally going line by line until it has finished the image.
There are two primary types of printheads that will be used in the digital printing process, piezoelectric and thermal. These print heads differ in the types of images they are used to create as well as how the image is formed.
While both printheads use drop technology to place ink onto your chosen medium, each of the different printheads will function in different ways. In the piezoelectric print head, there are microscopic piezoelectric elements that are built in behind each of the print nozzles. To drop the ink, an electrical charge will be applied to the element which will move the nozzle backward. When this movement occurs, an exact amount of ink will be deposited onto the substrate.
Since this type of printhead is controlled by an electrical charge, there is a great degree of control over the amount of ink that is being dropped as it can function in the same ways as an on-off switch would. These printheads are known for being able to create perfectly formed dots in a variety of sizes. Piezoelectric printheads are best for UV cured, aqueous, and solvent-based ink.
The alternative to piezoelectric printheads is thermal inkjet technology. In thermal technology, the printhead is operated by heat instead of electricity. The concept of thermal printing is similar to the way in which water boils. The thermal technology will electrify the microscopic resistors that lay behind the print nozzle creating an intense heat. As this heat occurs, it will vaporize the ink, creating bubbles that will expand rapidly and in effect explode onto the paper or substrate.
Once the ink has been expelled from the nozzles, it will cool quickly and then refill, repeating the process. Thermal printheads are most suitable for water-based inks such as latex inks used for outdoor signage as well as a number of textile applications.
Choosing the proper printhead is necessary when using specific inks but also to achieve the desired results from your printed piece. During printing, the individual drops of ink that are put onto the substrate will affect the overall quality of the image. Smaller drops will produce better definition and higher resolution. This is primarily better when creating easy to read text, especially text that may have fine lines.
The use of larger drops is better when you need to print quickly by covering a large area. Large drops are better for printing larger flat pieces such as large format signage. If your piece requires high resolution, has small or fine details, using a piezoelectric printhead that has better control of the size of the droplets will provide you with the best quality image. For pieces that might be larger but less detailed, thermal technology can make producing them less costly and often provide you with a piece that is suitable for your needs.
The ink you use and the quality and detail that your final piece requires will be the two vital components that determine which type of printhead will work best for your printing project.