A quarter century years ago, technicians at Casio and Panasonic invented a printing technology they termed LED (light-emitting diode). It was much cheaper to produce LED printers than laser printers, and they were also smaller, quieter and used less power than lasers, writes Erica Marks, product manager in the Xerox division at Bytes Document Solutions.
But after five years, the world had largely forgotten LED and laser predominated. That’s because LED printers were not of sufficient quality. They could only push out 600dpi resolution, while laser printers’ resolutions marched ever upward. The intensity of the print also varied from one LED to another.
Type was furry, image edges were jagged, halftones were fuzzy and colour reproduction mis-registered. Another problem was that, to correct these issues required someone to open the cover of the printer and manually fiddle with its parts. That was done either by someone at the factory or a clued-up end-user.
Also, if one of the LEDs in the array failed, then the entire print head had to be replaced by the manufacturer. LED was, in a word, a headache.
That said, LED and laser printers share many similarities. They employ the same basic method of applying toner to paper – static electricity. An electrical charge is built up on the drum and, as it rotates, a light is shone on the surface to draw an image of electrical charges.
Positively charged toner is then applied and it sticks to the negatively charged portions of the drum. Toner is then transferred from the drum to the paper and, using heat and pressure, toner is melted to the paper through a fuser.
LED may have been a failure, but people at Fuji Xerox and Nippon Electric Glass put their boffins together and bandied about technologies such as self-scanning integrated circuitry, optical technology and an application specific integrated circuit (ASIC) chip driver.
From the think-tank emerged a print head with uniform optical characteristics for high resolution imaging – the HiQ LED Printhead. And it redefines the LED printer.
The new print head has some fancy numbers, such as 14,592 LEDs. It also has a shiny new self-focusing lens array design. Each LED array, and there are four of them, packs in 1,200 diodes per inch. Then there’s the brain of the thing – the ASIC chip.
But what does all that mean to users? A HiQ LED printer will provide 1200x2400dpi resolution, which is directly comparable with the current crop of laser printers.
But now with HiQ LED, users also get all of the traditional benefits of LED – quiet operation, less power consumption, smaller size, and, most importantly, reliability – all without any of the problems that came before.