| 摘要 |
Apparatus and method for monitoring print quality produced by a digital printing mechanism in real-time. Print quality is measured by: generating a background reflectance signal representative of the reflectance of said substrate; scanning the image to generate a post-print reflectance signal; comparing said reflectance signal with said post-print reflectance signal; and, if said postprint reflectance signal is greater than a predetermined fraction of said reflectance signal, generating an output signal indicative of poor quality. In one embodiment of the invention, the output signal is also generated if the post-print reflectance signal is less than a predetermined minimum value. In another embodiment of the invention, the print mechanism is comprised in a postage metering system and the output signal inhibits further printing. In another embodiment of the invention, the background reflectance signal is compared with the post-print reflectance signal to classify the post-print reflectance signal as being satisfactory, unsatisfactory, or doubtful; and if the post-print reflectance signal is doubtful, printing a test pattern and waiting for an operator response; and then if the operator response indicates said test pattern is acceptable, accepting the indicia; and if the operator response indicates the test pattern is unacceptable, rejecting the indicia; and if the operator response indicates the test pattern is acceptable, adjusting the comparison to classify a greater portion of postprint reflectance signals as satisfactory; and if the operator response indicates the test pattern is unacceptable, adjusting the comparison to classify a greater portion of post-print reflectance signals as unsatisfactory.
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