Recorders – Performance of multiple functions of steam and gas engines – Pressure responsive element
Patent
1989-08-21
1992-07-07
Fuller, Benjamin R.
Recorders
Performance of multiple functions of steam and gas engines
Pressure responsive element
346 75, 346140R, G01D 1800
Patent
active
051286912
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of checking the printing of an ink jet printer.
2. Description of the Prior Art
The applications of this type of printer, in the industrial marking field in particular, increase regularly. Purely by way of illustration, there may in particular be mentioned the printing of "use by" dates on agro-alimentary products or batch numbers. Such marking is carried out more and more using ink jet printers of the "continuous deflected ink jet" type. The correct operation of such printers is governed by a number of relatively complex parameters which must be perfectly controlled if it is desired to obtain irreproachable printing quality. Despite the numerous improvements introduced these latter years in such printers, they are not proof against drifting of one or other of the parameters governing their operation, which may result in degradation of the quality of the writing. It is further known that, in most cases, such degradation of the writing quality has a typology in relation with the defective parameter. For example, the absence of an impact of droplets on the support to be printed may mean that the printing head needs cleaning. Similarly, to a fault in the positioning of the droplets there may correspond an abnormal ejection speed of the droplets or an incorrect speed of the movement of the head. Another problem may arise in so far as the size of the droplets is concerned. Furthermore, manufacturing or packing lines are more and more automated and permanency of the quality appears as of prime importance. Finally, since the marking function comes at the end of the production line, any defective marking results in unacceptable losses.
SUMMARY OF THE INVENTION
The object of the present invention is to overcome these problems by describing a method and device for anticipating the imminence of a break-down of quality; after its appearance; is too late.
The invention relates more precisely to a method of checking the printing quality of a jet printing head characterized in that it consists: marking;
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood from the following explanations and the three accompanying figures which schematically illustrate three variants of construction of a device for implementing the method of the invention, wherein:
FIG. 1 is a control frame of a matrix comprising a column of three dots;
FIG. 2 is a control frame formed of a matrix of five dots; and
FIG. 3 is a control frame of fifteen dots.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
One of the features of the method of the invention resides in the fact that it consists on the one hand in creating a specific control frame, at given times and/or positions and in reading same so as to compare it with a control frame of the same type serving as reference.
The control frame may be independent, i.e. independent of the text to be printed or connected to the printer or other control members of the line. The pattern to be checked is defined and specified to the control system in real time.
According to another feature of the invention, the control frame is formed of a series of dots which can be printed either systematically, or regularly at a fixed frequency, or regularly at a frequency resulting from an apprenticeship procedure related to the specific conditions of use. This control frame is therefore printed in addition to the useful message, in general before the latter but not limitatively.
According to another feature of the invention, the control frame is defined as a frame formed of a succession of remarkable dots. These dots are positioned so that checking thereof makes it possible to guarantee that the printing is correct with sufficient probability. For a given frame and under normal operating conditions, the position of the different impacts is perfectly well known and unique within a given tolerance. If the operating conditions of the head worsen (particularly at the printing, ink, droplets charge voltage, defl
REFERENCES:
patent: 3992713 (1976-11-01), Carmichael et al.
patent: 4675696 (1987-06-01), Suzuki
patent: 4800396 (1989-01-01), Hertz
Millet Jean-Claude
Regnault Luc
Fuller Benjamin R.
Imaje (SA)
Preston Gerald E.
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