Recorders – Markers and/or driving means therefor – With ink supply to marker
Patent
1990-12-28
1993-01-26
Fuller, Benjamin R.
Recorders
Markers and/or driving means therefor
With ink supply to marker
B41J 205
Patent
active
051825783
DESCRIPTION:
BRIEF SUMMARY
The invention is directed to a heating mechanism for warming the ink in the write head of an ink printer means wherein the wire head comprises a plurality of ink channels ending in discharge openings and comprising individually drivable, electrothermal transducer elements allocated to every ink channel under whose influence the ink in the region of a transducer element in the ink channel is suddenly heated until an ink vapor bubble is formed, and, in particular, whereby the write head is arranged in a write head carrier that is large in area in comparison to the write head.
A known principle for portraying characters on a recording medium is based upon ejecting individual ink droplets from the nozzles of a write head that is a component part of an ink printer means the ink drops, being ejected therefrom under the influence of a control means. Characters and/or graphic patterns are constructed grid-like on the recording medium by coordinating the ejection of individual droplets and the relative motion between the recording medium and the write head. The operational reliability and the quality of the recording are highly dependent on the uniformity of the droplet ejection, i.e. the individual droplets ejected by a drive pulse must have a defined size and must leave the nozzle of the write head with the respectively same speed. The influence of the viscosity of the ink is extremely critical for a uniform droplet ejection. This is highly dependent on the temperature. It is therefore already known to hold the temperature of the ink in an ink printer head a constant value. It is known (in German Published Application 26 59 398 for example) to provide a heating element in the nozzle plate for a write head wherein individual ink channels are provided that end at discharge nozzles of a nozzle plate. It is also known for such write heads to provide an induction coil in the region of the nozzle plate and heat to the nozzle plate by eddy currents and hysteresis losses (in German Published Application 35 00 820) for example.
It has recently been disclosed to achieve the ejection of individual ink droplets in that an ink vapor bubble is produced in the region of an electrothermal energy transducer arranged in the ink channel, this ink vapor bubble ejecting a defined ink volume from the ink channel as a droplet. Such write heads can be constructed using what is referred to as thin-film technology. The temperature dependency cf the viscosity of the ink is also a very critical factor for write heads of this type. It is therefore also known for write heads of this type to improve the ejection conditions by warming the ink fluid. This can occur by additional heating elements acting on the ink from the outside (for example, see German Published Application 29 43 164 and German Published Application 35 45 689). PTC resistors are employed as heating elements for this purpose. The temperature of the ink in the write head can thus be brought to a defined value and held at said defined value in combination with a regulating circuit and with a temperature sensor element for which, for example, a high-temperature conductor or a PTC resistor can be utilized. Particularly in write heads having electrothermal transducers, however, relatively long heating times derive since the heating elements are superficially arranged on a write head carrier that is designed relatively bulky or, respectively, large in area. The reason for this is that measures for cooling must be provided under certain circumstances for write heads with electrothermal transducers because of the warming of the ink occurring during an ongoing printing operation. The write head is usually arranged on an aluminum plate for this purpose that serves as a cooling member. When the ink must be warmed upon turn-on, given operation with few nozzles or after longer-lasting printing mode of the ink printer means, the cooling member must then also always be heated as well.
Although it is already known (in German Published Application 29 43 164), for example, to arrange a heating c
REFERENCES:
patent: 4275402 (1981-06-01), Kern
Goepel Ernst
Schierjott Rudolf
Bobb Alrick
Fuller Benjamin R.
Mannesmann AG
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