| 摘要 |
Ink printing mechanisms operate with a very low degree of noise and can be used advantageously as output printing mechanisms in data processing systems because of the high printing frequencies which are possible with them. With these printing mechanisms it is disadvantageous that the outlet openings of the outlet nozzles are easily blocked by ink slugs. As a result, uniform formation of ink droplets, which is required in order to obtain print of uniformly high quality, is no longer possible. The object of the invention is to detect the failure of droplet formation at the individual outlet nozzles at an early point. For this purpose, the outlet openings and/or the surfaces surrounding these openings are sensed by a sensor device (53) which is composed of an optical transmitter (61) and an optical receiver (63). By means of a control device (35) which is connected to the optical receiver (63), a control signal is produced when the reflection intensity deviates from a comparison intensity. This control signal either triggers rinsing of the print head (7) or triggers a visual or audible signal. As a result, bad printing quality is quickly detected. <IMAGE>
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