Printers and copiers, especially the high end products, benefit from compressing the data by being able to store multiple pages of data in local RAM. The compression chips that AHA provides allow data compression ratios of typically around ten to one or higher for bitonal image data. The StarLite family products are architecturally very flexible and allow predictable one-byte per clock simultaneous compression and decompression at data throughput speeds of 66 MBytes/sec.
Compression Benefit In Copiers And Printers
There are two major reasons for using compression in peripheral devices such as copiers and printers. One is data communication speeds over a network are improved if you first compress the data before sending. The high level page description language in most cases does a decent job of solving this problem, and may also include data compression. The other benefit, and the main reason compression ASICs are used in these devices, is to maximize the amount of rasterized image data that is stored in local RAM in the copier or printer.
A copier first scans a multiple page document, compresses and stores these pages in local RAM, and then uncompresses each page as it is sent to the printer. High speed print engines require the compression-decompression ASIC to be consistently fast enough to keep up with the printing speed. In print engines using laser technology, this is an absolute requirement since the printer cannot slow down or wait once it begins to print a page. Ink jet printers can slow down if necessary to wait for a slowly decompressing page. Obviously this is not a desirable condition in any case.
AHA provides lossless compression-decompression ASICs of several different types. The AHA35xx devices are ALDC half duplex compression-decompression devices. StarLite (AHA34xx) devices are full duplex compression-decompression devices that use a proprietary algorithm optimized for bitonal image compression.