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Host Dot-Density Control for Thermal Printing in Receipt Printers Disclosure Number: IPCOM000198975D
Publication Date: 2010-Aug-19
Document File: 3 page(s) / 43K

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The Prior Art Database


Receipt printers employ the use of thermal printing technology for its speed and accuracy in printing. Thermal Printing Technology employs the use of accurately burning marks on special receipt paper to make an imprint on the receipt paper. The intensity of the dots are controlled by the print head to prevent undesired out comes from the thermal printing - smudging, burning, etc. This calculation is traditionally performed on the printer itself. Due to its limited computing capacity, this often introduces latency in the processing of the data for printing. This patent utilizes the existing computational power of the host to aid and quicken the process in thermal receipt printing. The host will pre-calculate the intensity required for each dot per line of printing and thus pumping this information down to the printer to do a direct translation of bytes into instruction to control the thermal intensity of the print head per line of image.

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Host Dot-Density Control for Thermal Printing in Receipt Printers

Image printing was never designed for receipt printers due to various restrictions in processing and memory capacity in both the host and the device.

Current thermal printing is able to print lines of dots at a very fast rate (80 lines per second) which out-performs the processing capability of modern receipt printers. The reason for the latency in preparing the image is due to the calculation of the dot-density per line of dots in the image to be printed. With the limited processing capability of the printer, this becomes an expensive procedure.

Due to the latency difference in the image preparation and the actual printing, the printer stepper motor is not able to maintain a constant velocity throughout an entire image. The inertia of the stepper motor causes an iterated pause between each image chunk to be printed and hence causing white lines to appear in an image print


Utilizing the superior memory and processing capacity of the host, the calculation of the dot-density can be off-loaded to the host, reducing the processing load of the printer. This way, the printer is able to take the processed image from the host and send it directly for printing, drastically reducing the image-preparation time.

With the reduced load of the printer, the printer would be able to buffer the image-chunks to be printed more efficiently and quickly. With the thermal head printing buffer being kept filled with ima...