Patent Application
20060039731
Electrophotographic printer or copiers, for example laser printing systems, generate (in a known manner) potential images of images to be printed on an intermediate image carrier, for example a photoconductor drum or a photoconductor belt, and ink these with toner. The toner images are then transfer printed onto a print substrate, for example a paper web. In order to permanently bind the toner images with the print substrate, this is guided through a fixing station in which a fixing unit melts the toner images via heat so that they bond with the printing substrate.
Thermal printing fixing (for example from EP 0 593 813 A1) or radiant heat fixing (for example from DE 198 27 210 C1) can be used for fixing. In thermal printing fixing, the print substrate according to EP 0 593 813 A1 is directed over a pre-heating saddle and subsequently between a fixing roller and a pressure roller as a fixing unit. The print substrate (and with it the toner images) is pre-heated by the pre-heating saddle; the actual fixing occurs via the fixing roller and the pressure roller. In the radiant fixing, for example according to DE 198 27 210 C1, the toner images on the print substrate are exposed to the radiant heat, for example of an infrared radiator as a fixing unit.
The requirement for heat capacity to fix the toner images depends on the properties of the print substrate, for example on its weight, its dampness, its absorption property, its heat conductivity, etc. The print substrate weight is taken into account in the thermal printing fixing according to EP 0 593 813 A1. The print substrate weight is input by the operator or is scanned and a signal characterizing the requirement for heat capacity is supplied to a regulation circuit that correspondingly adjusts the temperature of the pre-heating saddle and with it the temperature of the print substrate.
In DE 25 03 953, a radiant heat source is used for fixing the toner images. A radiation detector responding to infrared radiation is fastened at a mounting to receive radiation which is substantially blocked when the medium passes between the radiation detector and the radiant heat source. The output from the radiation detector is used to control energy to the radiant heat source.
An object to be solved is to specify an arrangement with which all properties of the print substrate and additionally the environment conditions of the printing device (such as room temperature, environmental humidity) are considered in the setting of the heat capacity requirement of the print substrate, in particular at the beginning of the printing.
In a system or method for determining a heat capacity requirement of a print substrate to be applied by a fixing unit of a fixing station in an electrophotographic printer or copier, a measurement arrangement is provided comprising a reference radiation source and a temperature sensor. The reference radiation source exposes the print substrate to a radiant heat. The temperature sensor measures the heat emitted by the print substrate. An evaluation circuit determines the heat capacity requirement of the print substrate from a result of the measurement.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and/or method, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur now or in the future to one skilled in the art to which the invention relates.
The preferred embodiments have the advantage that the heat capacity requirement of the print substrate necessary in order to achieve an acceptable fixing of toner images on the print substrate is known.
It is particularly advantageous that the heat capacity requirement can already be known at the beginning of the printing. At this point in time, in unit could be adjusted so that they supply the heat capacity requirement of the print substrate; rather, a lead temperature is pre-set. Only when the printing event has begun and the fixing station is functioning can the actual fixing temperature be measured in the known printing devices and the desired fixing temperature be readjusted corrected from the measurement result.
In a first exemplary embodiment, the reference radiation source and the temperature sensor can be arranged relative to one another such that a region on the print substrate is exposed to a radiant heat and this region is simultaneously measured by the temperature sensor, such that no movement of the print substrate relative to the measurement device is required. For example, a reference radiation source and a temperature sensor can be inclined relative to one another so that the radiant heat impinges on the print substrate at an angle and the temperature sensor measures the reflected radiant heat.
In a second exemplary embodiment, a reference radiation source and a temperature sensor can be arranged relative to one another such that the surface on the print substrate is initially irradiated and is sampled by the temperature sensor after further movement of the print substrate. The reference radiation source and the temperature sensor can then be aligned perpendicular to the print substrate and, in the measurement event, the print substrate can be moved relative to the reference radiation source and the temperature sensor. In a printing device it is practical to utilize the movement of the print substrate that is already provided.
The heating of the print substrate by the reference radiation source is chosen so that no variation of the properties of the print substrate occurs. In this way the later fixing event is not negatively influenced.
Furthermore, it is advantageous when the temperature sensor is aligned so that it samples as a measurement area the middle region of the area of the print substrate irradiated by the reference radiation source. The measurement surface can thereby be selected significantly smaller than the irradiated surface, and with this measurement errors due to non-uniform radiation distribution can be prevented.
The arrangement can be designed so that the reference radiation source is initially activated for the measurement event and is subsequently deactivated again. This can occur via mechanical or electrical switches. The switching should thereby be shorter than the cooling time of the print substrate. The temperature sensor can then measure at least the cool-down curve. Naturally the temperature sensor can then measure both the warm-up curve and the cool-down curve. From the measurement results, for example from the amplitude and/or the slopes of the curves, the evaluation circuit can determine the heat capacity requirement of the print substrate that the fixing unit must apply in the printing event.
The preferred embodiments can be advantageously used when the fixing unit is a radiant heat source. The reference radiation source can then exhibit an emission curve corresponding to that of the radiant heat source. In this case the radiant heat source can also be used as a reference radiation source.
In a printing device, reference radiation source and temperature sensor can be selectably arranged at different locations. For example, they can be arranged before the transfer printing point at which toner images are transferred onto the print substrate. The measurement is then not influenced by the heating of the printing device. It is also possible to arrange the reference radiation source and the temperature sensor adjacent to and before the fixing station. Here, however, the toner allocation on the print substrate and the heat effect of the fixing station are to be taken into account. Naturally, the measurement arrangement can also be arranged such that it can move on the transport path of the print substrate in order to be able to implement the measurement at various points of the transport path. In order to prevent an additional hardware expenditure, a radiator of the radiant heat source can be used as a reference radiator and a sensor present at the output of the fixing station for measurement of the outlet temperature can be used as a temperature sensor.
A measurement arrangement made up of a reference radiation source 10 and a temperature sensor 14 that can be used in the preferred embodiment results from
When a fixing station according to DE 198 27 210 C1 (this is referenced in the disclosure) is used, the fixing unit is comprised of a radiant heat source (of course other types of heat sources may be used.). The measurement arrangement then provides particularly precise measurement results since it can be simulated in terms of its emission curve of the radiant heat source. The print substrate 11 is locally heated via a combination made up of radiation density and irradiation time. The reference radiation source 10 is deactivated by means of a mechanism (for example a diaphragm) or electrical switch 17 (
In the exemplary embodiments of
In a principle image,
The measurement signals 20 are evaluated by the temperature sensor 14 with the circuit according to
While preferred embodiments have been illustrated and described in detail in the drawings and foregoing description, the same are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention both now or in the future are desired to be protected.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 040 777.0 | Aug 2004 | DE | national |
