DE102007022796A1 - Print head controlling method for printer i.e. thermal transfer printer, involves calculating modified temperature of pressure elements, and determining required heat energy amount from modified temperature of pressure elements - Google Patents

Abstract

The method involves defining a thermal transfer variable characterizing thermal transfer between two model components, by a thermal model (108) for the model components. A modified temperature of pressure elements (102.3) is calculated by the thermal transfer variable and heat energy entry into the pressure elements. A required heat energy amount is determined from the modified temperature of the pressure elements, where the thermal model comprises a cooling body as the model components.

Description

The The present invention relates to a method for driving a according to the thermal transfer principle working printhead with several Printing elements, in which in a determination step for the respective pressure element a required amount of electrical heating energy is determined, which is to be supplied to the pressure element to Color from a color carrier assigned to the print head to a color carrier associated substrate to transfer a pixel of a printed image. In a feeding step, the one determined in the determining step is determined Heat energy supplied to the respective pressure element. The determination of the amount of heating energy takes place in the determination step using a thermal model of printhead assembly and color carrier device. The invention further relates to a Printer, which is suitable for carrying out the invention Method is suitable.

The machine readability of barcodes, in particular of two-dimensional ones Barcodes, depends heavily on the print quality. This is especially true for two-dimensional barcodes very small module sizes. For example for the postage stamps accepted by the Canadian Post demanded a two-dimensional barcode made of 48 × 48 Modules (printed or unprinted rectangular fields) is built on an area of 1 in × 1 in, so that an edge length of the respective module of about 0.5 mm.

One essential criterion for print quality and Thus the machine readability of such a barcode is to a uniform size the modules in both directions and on the other a uniform Coverage across the entire barcode.

In such thermal transfer printers, as z. B. from the DE 40 26 896 A1 are known to obtain a high-quality barcode, the respective printing element of the printhead for each pixel to be printed with a comparatively precisely metered amount of energy must be supplied to melt the color particles reliably in the desired amount or spatial extent of the carrier material of the ink ribbon. Depending on the current temperature of the respective pressure element more or less energy must be supplied to achieve the optimum melting temperature.

From the DE 10 2004 063 756 A1 It is also known in the context of franking imprints to use different sets of printing parameters for different areas of a franking imprint with different types of print images (plain text / graphics, one-dimensional barcode, two-dimensional barcode) in order to meet the different requirements of these types of print images.

The calculation of the energy to be introduced for each pixel to be printed in the relevant pressure element is done in each case as in the DE 40 26 896 A1 known printers using a thermal model of the printhead. In this case, the required amount of heating energy is calculated taking into account the energy input into the pressure element, which results from the heat conduction from all the printing elements with which previously printed, as well as the residual energy, which still comes from a previous printing process with the current pressure element.

Herewith Although a comparatively precise control of the printing elements possible. However, there is the disadvantage that for each pixel to be printed a relatively complex calculation what is the processing speed for a printed image and thus the throughput of the printer reduced. the can in the known printers only by a correspondingly higher Processor performance, so therefore by a more complex and thus expensive processor counteracted.

Of the The present invention is therefore based on the object, a method or a printer of the type mentioned to ask, which or which the above-mentioned disadvantages or not at least to a lesser extent and in particular a simple and economical improvement of the print quality, especially with a barcode enabled.

The The present invention solves this problem on the basis of a method according to the preamble of the claim 1 by the specified in the characterizing part of claim 1 Characteristics. It continues to solve this task starting from a printer according to the preamble of the claim 21 by the specified in the characterizing part of claim 21 Characteristics.

The present invention is based on the technical teaching that a simple and economical improvement of the print image quality, especially in the area of a barcode to be printed, he is possible if a simplified but sufficiently precise thermal model of the print head and color carrier assembly is used to determine the amount of heating energy required. Thus, it has been shown that with reduced computational effort, a sufficiently high print image quality can be achieved even if the setting of the amount of heating energy in place of the known, for each pixel to be printed on the same scheme running global calculation of energy over a pairwise thermal consideration of adjacent components the printhead is done. This simplistic pairwise consideration allows a sufficiently simplified calculation of the amount of heating energy for the respective pressure element, if it is sufficiently approximated to the real thermal conditions.

According to one The first aspect of the present invention therefore relates to a method for driving a printer head operating on the thermal transfer principle with several printing elements, in which in a detection step for the respective pressure element a required electrical Heating energy is determined to supply the pressure element is to color from a color carrier associated with the printhead to a color carrier associated substrate to transfer a pixel of a printed image. In a feeding step, the one determined in the determining step is determined Heat energy then fed to the respective pressure element. The determination of the amount of heating energy takes place in the determination step using a thermal model of printhead assembly and color carrier device. The thermal model includes as model components the printing elements, the ink carrier device and at least one adjacent to the printing elements element of Printhead. The thermal model defines for Couples of neighboring model components undergo heat exchange heat exchange variable characterizing between the two model components. Using the heat exchange quantities and the Heizenergieeintrags in the pressure elements in a previous Feed step is changed for the model components Temperature of the pressure elements calculated. From the changed Temperature of the pressure elements then becomes the required amount of heating energy determined.

The Heat exchange size can be any Size, which is the heat exchange characterized between the two model components concerned. Preferably, the heat exchange quantity to a thermal conductivity, as with such Value a simple, immediate calculation of temperature changes the two currently considered model components possible is.

The thermal model can basically all consider pairs of adjoining components of the printhead. A particularly advantageous simplification of the thermal model without significant impact on its accuracy, however, is achieved if only couples are considered, the one sufficient have large area contact area. therefore Thus, couples can advantageously be neglected which are adjacent, but this is not worth mentioning have flat contact area. Such couples can be excluded from the calculation or with a heat exchange size be considered equal to zero. Preferably, therefore provided that the thermal model for pairs of adjacent Model components that have a flat contact area, a Heat exchange variable not equal to zero defined and additionally or alternatively for pairs of neighbors Model components that do not have a flat contact area have a heat exchange quantity equal Zero defined.

A further simplification of the thermal model, without appreciable Influence on the accuracy of the model is achieved when the heat exchange between the printing elements with each other is neglected. This is due to the low heat capacity the pressure elements, the relatively small contact surface the pressure elements with each other and the other hand, large Contact surface of the printing elements with the color carrier or the rear adjacent components the printhead possible. Preferably, therefore, it is provided that the thermal model for pairs of adjacent printing elements no heat exchange size or heat exchange size defined as zero.

The Modeling the backward, d. H. on the Color carrier side facing away from the printing elements adjacent Components of the printhead take place in any suitable manner. This can be any number of different model components To be defined. It is particularly advantageous if at least the usually glaze wall immediately adjacent to the printing elements is modeled by at least one, preferably a plurality of glaze wall elements becomes. Preferably, therefore, it is provided that the thermal model as model components, a plurality of adjacent to the printing elements Includes glaze wall elements of the printhead.

Furthermore, it is also advantageous to also model the ceramic substrate adjoining the glaze wall as a rule via at least one, preferably a plurality of ceramic substrate elements. Preferably, therefore provided that the thermal model comprises as model components a plurality of ceramic substrate elements adjoining the glaze wall elements.

After all it is an advantage, even the usually different ceramic substrate adjacent heat sink as at least one model component to model. It is preferably sufficient, the heat sink over a single element to model, as for the heat sink usually because of its high heat capacity sufficient accuracy can be assumed that it approximates has constant temperature. It is therefore preferred that the thermal model as a model component at least one heat sink , wherein the thermal model in particular for the Heatsink an infinitely high heat capacity and / or defines a constant temperature.

A further advantageous simplification, which determines the accuracy of the determination not significantly affects the calculation effort but clearly reduced, can be achieved when the thermal model for the ink carrier device an infinitely high heat capacity and / or defines a constant temperature. This justified, the at a pressure on the thermal transfer principle of the color carrier always transported with respect to the printing elements so that each time you print a new color carrier section having substantially unchanged properties.

at preferred variants of the method according to the invention it is provided that in the determination step in a first step for the respective pressure element from the pressure element in the previous feeding step supplied electrical Amount of heating energy and the heat capacity of the pressure element a change in temperature due to the amount of heating energy of the printing element is calculated. in a second step using the thermal model for the couple neighboring model components δt in a given time interval changed from their mutual heat exchange resulting Temperature calculated. In a third step is changed from the Temperature of the pressure elements the required amount of heating energy determined.

The Time interval Δt is suitably chosen to be small those introduced by the simplification of the procedure Inaccuracies to keep sufficiently low. This is special at a sufficiently high printing speed given.

The Calculation of the individual temperatures preferably takes place successively, d. H. the temperatures are supplied for the Heating energy and the pairwise heat exchange just in succession calculated. This makes a particularly simple calculation possible. It goes without saying that both the first step and the second Step as well as the pairwise calculations in the second step can be done in any temporal sequence.

Preferably is in the third step for a printing element, which no pixel in the immediately following feed step of the print image should produce but in another subsequent Feed step again to produce a pixel of the printed image, determines a Vorpulsenergiemenge, the Vorpulsenergiemenge is less than the required amount of heating energy. This is ensures that the pressure element on one sufficient high temperature is maintained, so in the further following Feed step reaches the required temperature in each case becomes.

A particularly high print quality, especially in context with the printing of bar codes, is in a preferred variant obtained by the process according to the invention the thermal model as model components a plurality of glaze wall elements of the print head adjoining the print elements includes. In the third step is changed from the Temperature of the glaze wall elements for the neighboring ones Pressure elements a residual heat value Hy determined. In the third Step will then continue the required amount of heating energy for the respective pressure element using the associated residual heat value Hy and the number P by the printing element immediately following determined in sequence to be generated pixels.

With This residual heat value, it is possible in an advantageous manner, in determining the required amount of heating energy in the Glaze wall to store stored heat. Is the temperature of the glaze wall and thus the stored therein Heat is correspondingly large, that's enough under certain circumstances already transferred from the glaze wall in the adjacent printing elements Heat to melt off the color from the color carrier, so for one or even more next pixels no previous electrical heating energy is required. The residual heat value gives this back and thus allows a corresponding control of Heating energy.

Especially The residual heat value also allows a timely Switching off the heating energy in order to avoid in an advantageous manner that through the transferred from the glaze wall to the printing elements Heat even more pixels are printed, though this does not match the printed image. Preferably, therefore, it is provided that the residual heat value Hy for the image length of the without electrical power supply to the pressure element in the feed direction generated print image is representative and the required Reduced heating energy for the respective pressure element when the image length corresponding to the residual heat value Hy becomes is greater than that measured in the feed direction Image length of the printing element immediately following in sequence to be generated pixels. Preference is given here is that the required amount of heating energy is set to zero becomes when the residual heat value Hy corresponding image length to the nominal image length of a pixel to be generated larger is the image length measured in the feed direction to be generated by the pressure element immediately following in sequence Pixels.

The Determination of the required amount of heating energy depending on From the determined temperature of the heating elements can basically done in any suitable manner. So can be provided that the heating energy for each point of the printed image always takes place according to the same scheme. Especially with printed images with over longer stretches of consistent image sections or Image sections special structure (for example, bar codes, in particular two-dimensional bar codes) is preferably provided that the required amount of heating energy depending on the Location of the pixel is determined in the printed image to be generated. So it has been shown that with reduced computational effort even then a sufficiently high print image quality can be achieved can, if a setting of the amount of heating energy without the known, for each pixel to be printed according to the same scheme ongoing precise determination of the amount of heating energy done. Rather, at least for pixels in certain places within a printed image, such as a barcode, a simplified, position-dependent determination of the required Heating energy amount done. This position-dependent investigation may be of the invention described above Determination be superimposed by means of the thermal model, to achieve higher accuracy.

So For example, assume this at the beginning of printing the barcode be that a higher amount of energy in the printing elements is to be introduced as in the middle or even at the end of the barcode. As well is for example at a bar code to the extending in the printing direction Margins of the barcode usually higher To introduce energy into the pressure elements. Furthermore, in particular Two-dimensional barcodes are usually designed to be specific Setting the barcode (usually module columns or rows in Area of the edges as well as in the middle of the barcode) continuous Areas are printed to detect the barcode, the because of the continuous pressure, a lower, advance sufficiently exactly definable or more easily determinable energy supply need.

After all require in particular for two-dimensional barcodes on the in Printing direction of the rear end of a printed module lying pixels regularly because of the residual heat lower amount of energy than previously printed pixels. Especially in the case of two-dimensional barcodes, therefore, a simple position-dependent one is also involved Adjustment of the energy depending on the position of a pixel within a module of the barcode.

at preferred variants of the method according to the invention becomes the pressure element to be supplied in the feeding step Amount of energy in the determination step depending determined by the position of the pixel in the barcode and then adjusted accordingly. It is understood, however, that the amount of energy in other variants of the invention, even only one Parameters of the energy supply (for example, over the phase length the energy pulse supplied to the printing element) is position-dependent can be adjusted by this parameter depending on is varied by the position of the pixel in the barcode.

Especially Advantageously, this variant can be used when the Barcode a two-dimensional barcode with a plurality of matrix-like arranged printed and non-printed barcode modules, wherein a printed bar code module each having a plurality of pixels and a first pixel forms part of a barcode module forms. The to be supplied to the printing element in the feeding step Amount of heating energy can then be easier in the determining step Depending on the location of the barcode module in determined by the barcode. It is possible, yes based on the position of the barcode module in the barcode at least one Specify initial value for the setting of the amount of heating energy which at least simplifies the calculations in the determination step.

Preferably, the quantity of heating energy to be supplied to the printing element for the first pixel in the feeding step is then determined in the determining step as a function of the printing status of predetermined neighbor barcode modules, the predetermined neighbor barcode modules being the barcode module are adjacent and the print status of the respective neighbor bar code module reflects whether it is a printed or a non-printed bar code module.

Prefers becomes the respective printing element in the respective feeding step amount of heating energy to be supplied for the pixels a bar code module is determined using an energy template, wherein for each print status constellation the predetermined Neighbor barcode modules at least one separate energy template is provided.

at especially in connection with the printing of two-dimensional barcodes advantageous variants of the invention Method is provided that the barcode is a two-dimensional Barcode with a plurality of printed matter arranged like a matrix and non-printed barcode modules and the thermal model as model components, a plurality of adjacent to the printing elements Glaze wall elements of the printhead comprises, wherein the glaze wall elements aligned with the bar code modules. By this orientation the glaze wall elements on the bar code modules results in a particularly simple Investigations of the respective required amount of heating energy.

The Thermal model can basically be arbitrarily complex be designed. Depending on the available computing power a three-dimensional thermal model can be used. Preferably However, the thermal model is a two-dimensional model. So has been shown that with such a two-dimensional model for a wide range of printing applications, in particular in franking imprints, at significantly reduced computational effort a sufficiently precise adjustment of the amount of heating energy is possible.

Of the respective determination step can each immediately immediately before the associated Feed step done. However, it has been shown that it is advantageous Way is possible for a plurality of Feeding steps, especially for all to produce the Print image required feed steps, in advance a corresponding Number of investigation steps. hereby The actual printing process can be accelerated and thus the throughput of the printer.

Prefers In the process, the determination steps become invariant in advance Areas of the printed image performed. In particular, can be provided that for invariant areas of the printed image the investigation steps are carried out in advance for several printed images become.

According to one In another aspect, the present invention relates to a printer with a printing device operating according to the thermal transfer principle, a printhead with multiple printing elements, one with the printhead connected processing unit for driving the print head and comprises a memory connectable to the processing unit, and a color carrier associated with the printhead. The processing unit is configured to be in a determination step for the respective pressure element a required electrical Determine amount of heating energy to supply the pressure element is to color from a color carrier associated with the printhead to a color carrier associated substrate to transfer a pixel of a printed image. The processing unit is configured to be in a feed step the determined in the determination step amount of heating energy to the respective To supply pressure element. The processing unit is still configured to determine the amount of heating energy in the determining step using an at least partially stored in the memory thermal model of the arrangement of printhead and ink carrier device make. The thermal model includes as model components the printing elements, the color carrier device and at least an element of the printhead adjoining the printing elements. The thermal model defines for pairs of neighbors Model components a heat exchange between the heat exchange variable characterizing both model components. The processing unit is further adapted to be used the heat exchange quantities and the heat energy input in the printing elements in a previous feeding step for the model components a changed temperature of the printing elements to calculate. Finally, the processing unit adapted to from the changed temperature of the printing elements to determine the required amount of heating energy.

With leaves this printhead according to the invention the method according to the invention described above perform and there are the advantages described above and variants to the same extent, so in this regard only reference is made to the above statements.

In addition, it should merely be noted at this point that the data used during printing, for example the thermal model, the energy templates described above and / or phase length radio tions in a memory of the printing device of the printer or at least partially stored in a memory of the ink carrier device. The storage of at least part of this data in the ink carrier device brings with it in particular the advantage that a particularly simple adjustment of the printing process to the color carrier used is possible. Accordingly, the present invention also relates to a color carrier device, in particular an ink ribbon cassette, for a printer according to the invention which has a memory in which at least one model parameter characterizing the heat exchange between the color carrier device and adjacent components of the printer is stored. Furthermore, at least one energy template and / or the at least one phase length function may be stored permanently in this memory of the ink carrier device, which characterizes the amount of heating energy to be supplied to the respective pressure element in the respective supply step for the pixels of a barcode module.

The The method described above or the printer described above can can be used for any purpose. Preferably they are used in the field of the production of franking imprints, There are often barcodes with very small module sizes on print media with a strongly scattering surface quality with simultaneously high demands on machine readability be used. Accordingly, the present invention relates Invention further a franking machine with an inventive Printer.

Further preferred embodiments of the invention will become apparent from the dependent claims or the following description of preferred embodiments, which refers to the accompanying drawings. It demonstrate

1 a schematic representation of a preferred embodiment of the printer according to the invention, with which a preferred embodiment of the method according to the invention for driving a print head can be performed;

2 a schematic flow diagram of a preferred embodiment of the method according to the invention for driving a printhead, with the printer from 1 is carried out;

3 a schematic representation of a printed image, with the printer off 1 was generated using the method according to the invention;

4 a two-dimensional barcode on an enlarged scale, as in the printed image 3 Use finds;

5 a representation of a two-dimensional thermal model of the printhead, as in the method according to 2 Use finds;

6 an illustration of an energy template, as in the method of 2 Can be used;

7 an illustration of a phase length function, as in the method of 2 Can be used.

8th an illustration of a table for determining the amount of heating energy, as in a variant of the method 2 Can be used.

1 shows a schematic representation of a franking machine 101 with a preferred embodiment of the printer according to the invention 102 , The printer 102 is operated using a preferred embodiment of the process of the invention for driving a printhead.

The printer 102 represents the printer unit of the franking machine 101 dar. Next to the printer 102 includes the franking machine 101 still other components, such as an input / output unit 101.1 , a security module 101.2 in the form of a so-called PSD or SAD, in short a so-called SD, and a communication unit 101.3 ,

About the input / output unit 101.1 For example, a module with keyboard and display, a user can information in the postage meter 101 enter or information can be output to a user. The security module 101.2 provides backup functionalities to the physical and logical Securing the security-relevant data of the franking machine 101 to disposal. About the communication unit 101.3 can the franking machine 101 For example, be connected via a communication network with remote facilities, such as a remote data center.

The printer 102 includes, among other things, a processing unit 101.4 , a printhead 102.1 and a color carrier in the form of a ribbon cassette 103 , The processing unit 101.4 is a central processing unit of the franking machine 101 , which among other functions, the control of the printhead 102.1 when printing takes over.

The printhead 102.1 includes an electrical heating energy supply device 102.2 holding a number of n printing elements 102.3 supplied with heating energy. It should be noted at this point that the printing elements 102.3 in 1 are shown only schematically and the printhead 102.1 usually has a significantly higher number of printing elements, as in 1 is shown. The heating energy supply device 102.2 is used to supply the printing elements 102.3 with heating energy from the processing unit 101.4 controlled accordingly.

The ribbon cassette 103 is the printhead 102.1 so assigned to her ribbon 103.1 with his color carrier 103.3 the printing elements 102.3 of the printhead 102.1 contacted. For printing, the printing elements 102.3 (driven by the processing unit 101.4 ) from the heating power supply device 102.2 each supplied with a precisely metered amount of heating energy to local color particles of the paint layer 103.2 melt off, which is on the color carrier 103.3 of the ribbon 103.1 located. These color particles are then on a substrate 104 , here a letter to be franked, transferred. The letter 104 this is done on the printhead 102.1 passed and thereby by pinch rollers 105 against the ribbon in between 103.1 pressed.

The heating energy supply device 102.2 brings the required for each pixel electrical heating energy over a certain number Z of Heizenergieimpulsen a certain length, the so-called phase length in the corresponding pressure element 102.3 one.

The ribbon cassette 103 has a first memory 103.4 on when assigning the ribbon cassette 103 to the printer 102 in other words, when inserting the ribbon cassette 103 in the franking machine 101 , automatically via corresponding contact elements with the processing unit 101.4 is connected. In the first store 103.4 are the ribbon cassette 103 associated print parameters stored, which, as will be explained in more detail below, to control the printhead 102.1 be used.

3 shows a printed image in the form of a franking imprint 104.1 according to the specifications of Deutsche Post AG, with the printhead 102.1 on the letter 104 was generated. The franking imprint 104.1 includes different subareas 104.2 to 104.5 , This is the first section 104.2 a two-dimensional barcode and the second subarea 104.3 a one-dimensional barcode, while the third and fourth sections 104.4 and 104.5 each is an area with text and free graphics.

Regarding sharpness and contrast of the printed image 104.1 exist with the two-dimensional barcode 104.2 as he is magnified in 4 is shown, high demands on sharpness and contrast in the area of the edges of the rectangles or squares generated over the pixels, hereinafter referred to as bar code modules 104.6 be designated. This applies both in the printing direction D and across it.

To meet these high quality requirements in the field of barcodes 104.2 To satisfy, a sufficiently accurate adjustment of the amount of heating energy is required, the respective pressure element 102.3 is supplied. In order to achieve such a sufficiently accurate adjustment of the amount of heating energy for the respective printing pixel, in the present example, as will be explained in more detail below, a thermal model of the arrangement of print head 102.1 and color carrier 103.1 , Heizenergieschablonen and phase length functions used, which reduces the processing complexity in the processing unit 101.4 Compared to the known methods for setting this amount of heating energy and thus with sufficient print quality high throughput of the postage meter 101 guarantee.

The following is with reference to the 1 to 7 a preferred embodiment of the method according to the invention for driving a print head described with the printer 102 out 1 is carried out.

First, the procedure is in one step 106.1 started. It is recognized that a new ribbon cartridge 103 correctly in the franking machine 101 was used, reads the processing unit 101.4 the print parameters from the first memory 103.4 then, via corresponding contact elements with the processing unit 101.4 connected is. To ensure that the correct printing parameters are always used, it may be provided that the insertion of a new ribbon cassette 103 during operation of the franking machine 101 always restart the procedure with the step 106.1 forces.

The processing unit 101.4 stores the print parameters in one with the processing unit 101.4 connected second memory 101.5 in the form of a volatile memory of the franking machine 101 , It goes without saying, however, that in other variants of the invention it can also be provided that the second memory is a non-volatile memory.

In one step 106.2 a check is made as to whether a printing operation should be carried out, for example a letter 104 to be franked. If not, it becomes the step 106.2 jumped back.

If a printing operation is to be carried out, the processing unit 101.4 in one step 106.3 First, the print image to be generated 104.1 calculated. This is done in a conventional way, so it should not be discussed in detail.

Furthermore, the processing unit calculates 101.4 in the step 106.3 a thermal model of the assembly from the printhead 102.1 and the ribbon 103.1 as it is in 5 is shown by way of example, and optionally a number of Heizenergieschablonen 107.1 and a phase length function PF, as exemplified in 6 and 7 are illustrated, and their use will be explained in more detail below.

The thermal model 108 is a two-dimensional model of the arrangement from the printhead 102.1 and the ribbon 103.1 , It includes as a model components the ribbon (R) 103.1 , N printing elements (H) 102.3 of the printhead 102.1 , M Glaze Wall Elements (G) 102.5 of the glaze wall 102.6 of the printhead 102.1 , L ceramic substrate elements (C) 102.7 of the ceramic substrate 102.8 of the printhead 102.1 and a heat sink (S) 102.9 of the printhead 102.1 , The glaze wall elements (G) 102.5 of the glaze wall 102.6 are doing the barcode modules 104.6 of the barcode 104.2 aligned.

The thermal model 108 defines between each model component A and an adjacent model component B a heat exchange variable characterizing the heat exchange between the two model components A and B in the form of a thermal conductivity α _AB .

Thus, therefore, in the thermal model 108 on the one hand defines a thermal conductivity α _RH , which is responsible for the heat exchange between the pressure elements 102.3 and the ribbon 103.1 is characteristic. Furthermore, a thermal conductivity α _GH defined for the heat exchange between the pressure elements 102.3 and the respective glaze wall element 102.5 is characteristic. Furthermore, a thermal conductivity α _GG defined for the heat exchange between the adjacent Glurnwall elements 102.5 is characteristic. Furthermore, a thermal conductivity α _GC defined for the heat exchange between the respective glaze wall element 102.5 and the respective ceramic substrate member 102.7 is characteristic. Furthermore, a thermal conductivity α _CC defined for the heat exchange between the adjacent ceramic substrate elements 102.7 is characteristic. Finally, a thermal conductivity α _CS defined for the heat exchange between the respective ceramic substrate element 102.7 and the heat sink 102.9 is characteristic.

The thermal conductivity α _GH is in the previous step 106.3 from corresponding model parameters of the ribbon 103.1 calculated in the first memory 103.4 are stored and for this purpose by the processing unit 101.4 from the first store 103.4 be read out.

Simplifying is in the thermal model 108 assumed that both the ribbon 103.1 as well as the heat sink 102.9 have an infinite heat capacity c and accordingly each having a constant temperature. This simplification is, as already explained, without appreciable influence on the accuracy of the calculations, since the ribbon 103.1 is constantly renewed during printing and the (for example made of aluminum) heat sink 102.9 has a very high thermal conductivity.

Furthermore, in the thermal model 108 simplifying assumed that no heat exchange between the printing elements 102.3 takes place. This simplification is, as already explained above, without appreciable influence on the accuracy of the calculations, since the printing elements 102.3 one opposite the contact surfaces to the ribbon 103.1 or to the glaze wall 102.6 have low contact surface. Accordingly, there is no thermal conductivity between the printing elements 102.3 Are defined.

Finally, in the thermal model 108 For the sake of simplification, it is assumed that heat exchange only takes place between model components A and B, between which there is surface contact. Accordingly, there is a significantly reduced number of pairs for the model components, for which consideration of the heat exchange takes place. These couples are in 5 indicated by the arrows between the model components.

wobei:

T_A(t)

= Temperatur der Modellkomponente A zum Zeitpunkt t,

T_A(t)

= Temperatur der Modellkomponente B zum Zeitpunkt t.

For the heat exchange, ie the heat energy δQ transferred per time interval Δt from the model component A to the model component B, according to the model for small time intervals Δt (with Δt · α _AB <1):

in which:

T _A (t)

= Temperature of model component A at time t,

T _A (t)

= Temperature of model component B at time t.

In this case, the respective temperature, in particular at the beginning of a printing operation after a longer printing pause, for example, from that of the temperature sensor 102.4 determined temperature value determined.

wobei CA die Wärmekapazität der Modellkomponente A bezeichnet. Analog berechnet sich eine geänderte Temperatur T_B(t + δt) für die Modellkomponente B zu einem Zeitpunkt t + δt zu:

wobei c_B die Wärmekapazität der Modellkomponente B bezeichnet. Setzt man die Gleichung (1) in die Gleichungen (2) und (3) ein, so erhält man:

bzw.With the transferred heat energy bQ, a changed temperature T _A (t + δt) for the model component A is calculated at a time t + Δt:

where CA denotes the heat capacity of the model component A. Analogously, a modified temperature T _B (t + Δt) for the model component B is calculated at a time t + Δt:

where c _B denotes the heat capacity of the component model B. Substituting equation (1) into equations (2) and (3), one obtains:

respectively.

In other words, for a certain period of time, Δt can be between two with the print head 102.1 printed printing columns of the printed image 104.1 with the thermal model 108 for each printing element 102.3 calculate the temperature resulting from the heat exchange at the beginning of the new pressure column.

Furthermore, the increased temperature T _Hi (t + δt) of the respective pressure element (H _i ) resulting from the heat energy input Q _Ei 102.3 at the time t + δt with the heat capacity c _{Hi of} the i-th pressure element (H _i ) 102.3 according to the thermal model 108 be calculated:

In one step 106.4 therefore be with the thermal model 108 in a first partial step, first the temperatures T _Hi (t + δt) of the N pressure elements (H ₁ ; i = 1... N) resulting from the heat energy input Q _Ei 102.3 calculated according to equation (6). It is in the thermal model 108 According to the present example, an edge area on both sides 108.1 defined, each comprising virtual printing elements, which at no time heating energy is supplied to realize a simple view of the real printing elements at the top and bottom of the printing column.

In a second step of the step 106.4 are successively calculated using equations (4) and (5) for all pairs of model components A and B, the temperatures resulting from the heat exchange at time t + δt.

The in the second step of the step 106.4 determined temperatures of the N pressure elements (H _i ; i = 1 ... N) 102.3 are then used in the following to determine the required heating energy for the next pressure column. This is done in one step 106.5 first, the relevant pixel of the printed image selected.

In the simplest (in 2 not shown), let us consider the heating energy quantity Q _Ei in question in one step 106.6 depending on the calculated temperature simply from a table 109 read out how they are in 8th , where appropriate, a simple linear interpolation for intermediate values takes place. This value or a corresponding number Z of heating pulses is then stored in a suitable control data record.

If a pixel is actually to be generated, the column QE becomes out of the table 109 used. If this is not the case, a required pre-pulse energy is read out from the column QPE.

In this case, a consideration of the residual heat Hy of the associated glaze wall element continues to take place 102.5 , If its temperature is within a certain range, the energy stored herewith is sufficient to print a printed image with the length (in nominal pixel width) indicated in the column Hy even without the supply of electrical heating energy. If the number of pixels still to be printed in succession with the same printing element is equal to the value Hy of the table above the value 1 , no energy is supplied to the pressure element.

Alternatively, the determination of the amount of heating energy Q _Ei , as in 2 shown in the step 106.6 using heating energy stencils 107.1 and the phase length function PF.

in the present example, a Heizenergieschablonen sentence is provided is where in for different combinations of parameters the ribbon and the printing element temperature different Heizenergieschablonen are stored. The heating energy template to be used in each case becomes simply by using the current combination of input parameters selected for the relevant heating energy template set.

It is understood, however, that in other variants of the invention, instead of the heating energy template set, a calculation of the heating energy templates using a set of input parameters from a parametrized master energy template, in the second memory 101.5 is stored, can be provided.

These heating energy templates 107.1 are each assigned to a barcode module type and in the present example - according to the generation of the barcode modules 104.6 over a matrix of pixels - even built in the manner of a matrix. Every value 107.3 in the relevant heating energy template 107.1 denotes the number Z of heating energy pulses, which the heating energy supply device 102.2 the relevant printing element 102.3 supplies.

However, it is understood that in other variants in the invention can also be provided that the respective value in the heating energy template another for the adjustment of the pressure element 102.3 amount of heating energy required or representative size can be. In particular, the value may directly indicate a quantity of heating energy.

For each barcode module type, depending on the possible print status constellations, the Neighbor modules of a barcode module 104.6 a heating energy template set with several heating energy templates 107.1 in front. In the present example, the print status of the replica modules at the four edges of a barcode module becomes 104.6 considered.

The 6 shows, for example, a heating energy template for a particular barcode module type 107.1 for a print status constellation in which the left neighbor module, the upper neighbor module and the right neighbor module are printed (print status: N ⁺ ), while the lower neighbor module is not printed (print status: N ^- ).

According to the present invention are for different areas of the barcode 104.2 defined different barcode module types. Such is the barcode modules 104.6 the left module column 104.7 assigned a first barcode module type. The remaining barcode modules 104.6 the middle module row 104.8 a second barcode module type is assigned. The remaining barcode modules 104.6 the module line 104.9 above the middle module row 104.8 is assigned a third barcode module type, while the remaining barcode modules 104.6 the module line 104.10 below the middle module row 104.8 a fourth barcode module type is assigned. The remaining barcode modules 104.6 the right module column 104.11 is assigned a fifth bar code module type. The remaining barcode modules 104.6 the upper module row 104.12 a sixth barcode module type is assigned. All other barcode modules 104.6 Finally, a seventh barcode module type is assigned. It is understood, however, that in other variants of the invention, a different number and assignment of the bar code module types can be provided.

Each barcode module type is in turn assigned an energy template set with multiple energy template subsets. For each possible printing status constellation in the relevant barcode module type, an energy template subset is provided in the energy template set, from which then in each case a current heating energy template is generated in the manner described above 107.1 is selected. In the present example, therefore, arise for the barcode modules 104.6 of the seventh barcode module type 2 ⁴ = 16 different print status constellations and thus 16 different energy template sets. In contrast, arise for the barcode modules 104.6 of the barcode module type because of the always not printed left neighbor module only 2 ³ = 8 different pressure status constellations and thus only eight different energy template sets.

It It should be noted at this point that although this is a larger Storage capacity required because of easy selection However, the Heizenergieschablonen is possibly a small Computing capacity of the processing unit required.

Furthermore, the processing unit calculates 101.4 in the present example in the step 106.3 optionally a phase length function PF, as described in 7 is shown schematically. The phase length function designates the dependence of the phase length L of the respective pressure element 102.3 for generating a pixel supplied heating energy pulses from the number N of the module column to be printed. In other words, the phase length function PF defines as a function of the position of the pixel in the barcode 104.2 the phase length L and thus ultimately the amount of heating energy, which the pressure element 102.3 for generating this pixel is supplied.

Also, the phase length function PF is calculated in the present example using a set of input parameters from a parameterized master function MPF stored in the second memory 101.5 is stored.

In principle, any suitable parameters which have an influence on the one printing element can be used as the input parameter for the calculation of the phase length function PF 102.3 have to be supplied to generate a pixel amount of heating energy. In the present example, the phase length function PF is made using at least part of the first memory 103.4 read out printing parameters of the ribbon 103.1 as the input parameter as well as the current temperature of the printhead 102.1 representative temperature measured value T calculated as a further input parameter.

It however, it will be understood that in other variants of the invention instead the calculation of the phase length function over a Master function also provided a phase length function set in which for different combinations of the Input parameters different phase length functions stored are. The currently used phase length function then does not have to be calculated, but is based on the current Combining the input parameters simply from the relevant phase length function set selected.

It it is understood, however, that in other variants in the invention It may also be provided that for varying the amount of heating energy, which is to be supplied to the respective pressure element, depending from the position of the pixel to be generated in the barcode (in particular depending on the number of the module column, in the the pixel is located) also another the amount of heating energy influencing parameter used as the phase length L. can be. So it is possible, for example, to this Purpose the current and / or voltage of the heating energy pulses depending on the location of the pixel in the barcode along the printing direction D to vary.

The phase length function PF may be defined in any suitable manner. Thus, it may be defined via any suitable number of vertices, whereby values lying between these vertices may then optionally be interpolated. In this case, any desired course, in particular an arbitrarily curved course of the phase length function can be provided, as in FIG 6 is indicated by the dashed contour PF '.

As 7 can be seen, the master function MPF and thus the phase length function PF is defined in the present example by three bases, namely a start support point MPS or PS, an intermediate support MPM or PM and an end support point MPE or PE. The parameterization of the master function MPF can be selected such that, depending on the input parameters mentioned above, the phase length values L of the respective support point PS, PM and PE and the column value N of the intermediate support point PM can vary on the one hand. However, it is also possible that only part of these values will be varied.

The calculation of the current phase length function PF can be performed every step of the rth cycle 106.3 take place (with r ≥ 1). The calculation can also be linked to the occurrence of any other, temporal and non-temporal conditions or events. In particular, it can be provided that this calculation in the step 106.3 is performed only if one of the above input parameters of the calculation has changed by more than a predetermined value. This can be the case, for example, if a new ribbon 103.1 was used with correspondingly different pressure parameters or the temperature measured value T and thus the temperature of the print head 102 has changed by more than a predetermined value. It is also understood that it may be provided that such a change, depending on the strength even a restart of the procedure in the step 106.1 can force. Of course, the same applies to the selection of the phase length function in the variants mentioned without calculating the phase length function via the master function.

It is understood in this context that in other variants of the invention, both the master energy templates and the master function MPF in the memory 103.4 the ribbon cassette 103 can be stored. Likewise, in the variants described without master energy templates or master function, the heating energy templates or the phase length functions in the memory 103.4 the ribbon cassette 103 be saved.

According to the current in step 106.4 determined temperature and as a function of the barcode module type of the current barcode module to which this current pixel is assigned (hence, depending on the position to be considered current pixel in the barcode 104.2 ) selects the processing unit 101.4 in one step 106.7 then first the current heating energy template set. From this current Heizensergiesch48onensatz is then depending on the printing status constellation of the neighboring modules of the current bar code module (resulting from the in step 106.3 calculated print image) the current heating energy template is selected. From the current heating energy template, for example the heating energy template 107.1 out 6 , reads the processing unit 101.4 then the number Z of the heating energy pulses, the respective pressure element 102.3 to supply the current pixel, and stores this number Z in an appropriate control data set.

In one step 106.8 determines the processing unit 101.4 then as a function of the number N of the module column of the current barcode module to which this current pixel is assigned (hence, depending on the position to be considered current pixel in the barcode 104.2 ) from the phase length function PF, the current phase length L of the heating energy pulses, the respective pressure element 102.3 to supply the current pixel, and stores this phase length L in an appropriate control data set. In this case, the control values determined for the current pixel, that is to say the number Z and the phase length L, are stored correspondingly assigned to each other or suitably linked.

In one step 106.9 checks the processing unit 101.4 , if still for another pixel of the barcode 104.2 the control values for the control data record are to be determined. If so, go back to the step 106.5 jumped.

It should be understood that in advantageous variants of the method according to the invention with a particularly fast processing of the data it can also be provided that the processing unit 101.4 in a combination of steps 106.5 and 106.6 Immediately determines the values Z and the phase length L for a plurality of pixels associated with the current bar code module. Thus, for example, the values Z can be determined immediately for all pixels arranged in the same print column and then assigned the identical phase length L to them.

Likewise, if appropriate, even all the values Z for the pixels associated with the current bar code module can be determined, and corresponding values (also identical in this example) for the phase length L can then be assigned to them. In this case, the processing unit 101.4 then possibly even when storing the control values or subsequently make a corresponding sorting of the control values in the control data record, provided that a sequential arrangement of the control values for the control of the printing elements 102.3 is required.

Represents the processing unit 101.4 in the step 106 , notice that for no further pixel of the barcode 104.2 The control values for the control data set are to be determined in one step 106.10 checks if the print image contains another print column. If this is the case, it becomes the step 106.4 jumped back. Otherwise, that's the steps 106.4 to 106.10 comprehensive investigation step 106.11 to determine the required heating energy values completed and the processing unit 101.4 Controls after completion of all further preparations for the production of the franking imprint 104.1 in a feeding step 106.12 the printing elements 102.3 of the printhead 102.1 for the production of the franking imprint 104.1 at. Here, it uses the one described above in the determination step 106.11 generated control record.

The print of the franking imprint 104.1 takes place column by column. At this time, to generate a print column in a drive sequence using the control data set, all of them are printed according to the print image to be formed 104.1 to be addressed printing elements 102.3 of the printhead 102.1 from the processing unit 101.4 driven. In order to generate the next printing column, in a further control sequence using the control data set, all are then again printed according to the print image to be generated 104.1 to be controlled printing elements of the print head 102.1 driven.

Is no further pressure element to control, for example, because all columns of the printed image 104.1 are printed or a cancellation is made in one step 106.13 Finally, checks whether the procedure should be terminated. If this is the case, the procedure ends in one step 106.14 , Otherwise, it becomes the step 106.2 jumped back.

The present invention has been described above with reference to an example in which the control data (hence the amount of heating energy for the printing elements 102.3 ) were determined in advance for the entire print image. It is understood, however, that in other variants of the method it can also be provided that the determination of the control data (number Z and phase length L of the pulses) can be determined in advance for a plurality of successive print images. Furthermore, it is understood that in other variants of the method it can also be provided that the determination of the control data (number Z and phase length L of the pulses) for each individual control of a pressure element can be determined separately immediately before the control. Likewise, it is understood that in other variants of the invention, a procedure settled between these extreme variants can be provided. For example, the determination of the control data can take place in advance for the respective printing column. The determination of the amount of heating energy can in particular already take place while the control sequence for the preceding pressure column is still running, so that no appreciable loss of time is associated therewith.

The The present invention has been described above by means of examples, where a combination of the location of the pixel in question Bar code dependent control via a combination the use of heating energy stencils with the use of Phase length functions done. It goes without saying, that in other variants of the invention can also be provided one dependent on the position of the pixel in question in the barcode Control of the printing elements exclusively via Heizenergieschablonen or exclusively about to perform one or more phase length functions. Especially when using Heizenergieschablonen can then be provided be that the Heizenergieschablonen additionally in the Pressure direction D can be varied.

Farther the present invention has been exclusive using examples with a two-dimensional barcode closer described. It is understood, however, that the invention also for one-dimensional barcodes. In particular, the use of the phase length function is suitable excellent for the position-dependent setting the amount of heating energy in such one-dimensional barcodes.

After all the present invention has been exclusive described by way of examples with a postage meter. It It is understood, however, that the invention also applies to Any other applications can be used in which a print image is generated.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4026896 A1 [0004, 0006]
• - DE 102004063756 A1 [0005]

Claims (45)

Method for controlling a printhead working according to the thermal transfer principle ( 102.1 ) with several printing elements ( 102.3 ), in which - in a determination step ( 106.11 ) for the respective printing element ( 102.3 ) a required amount of electrical energy is determined which corresponds to the pressure element ( 102.3 ) is to supply color from a the printhead ( 102.1 ) associated color carrier device ( 103 ) on one of the color carrier device ( 103 ) associated substrate ( 104 ) to generate a pixel of a printed image, and - in a feeding step ( 106.12 ) in the determination step ( 106.11 ) calculated amount of heating energy the respective pressure element ( 102.3 ), wherein - the determination of the amount of heating energy in the determination step ( 106.11 ) using a thermal model ( 108 ) the arrangement of printhead ( 102.1 ) and color carrier device ( 103 ), characterized in that - the thermal model ( 108 ) as model components the printing elements ( 102.3 ), the color carrier device ( 103 ) and at least one element adjacent to the printing elements ( 102.5 . 102.7 . 102.9 ) of the printhead ( 102.1 ), wherein - the thermal model ( 108 ) for pairs of adjacent model components defines a heat exchange variable characterizing the heat exchange between the two model components, - using the heat exchange quantities and the heat energy input into the pressure elements ( 102.3 ) in a previous feeding step for the model components a changed temperature of the printing elements ( 102.3 ) and - from the changed temperature of the printing elements ( 102.3 ) the required amount of heating energy is determined. Method according to claim 1, characterized in that that the heat exchange quantity has a thermal conductivity is. Method according to claim 1 or 2, characterized in that the thermal model ( 108 ) - for pairs of adjacent model components having a flat contact area, defines a non-zero heat exchange variable and / or - defines a heat exchange variable equal to zero for pairs of adjacent model components that do not have a planar contact area. Method according to one of the preceding claims, characterized in that the thermal model ( 108 ) for pairs of adjacent printing elements ( 102.3 ) defines no heat exchange quantity or a heat exchange quantity equal to zero. Method according to one of the preceding claims, characterized in that the thermal model ( 108 ) as model components a plurality of to the printing elements ( 102.3 ) adjacent glaze wall elements ( 102.5 ) of the printhead ( 102.1 ). Method according to claim 5, characterized in that the thermal model ( 108 ) as model components a plurality of the glaze wall elements ( 102.5 ) adjacent ceramic substrate elements ( 102.7 ). Method according to claim 6, characterized in that - the thermal model ( 108 ) as a model component at least one heat sink ( 102.9 ), wherein - the thermal model ( 108 ) in particular for the heat sink ( 102.9 ) defines an infinitely high heat capacity and / or a constant temperature. Method according to one of the preceding claims, characterized in that the thermal model for the ink carrier device an infinitely high heat capacity and / or defines a constant temperature. Method according to one of the preceding claims, characterized in that in the determining step ( 106.11 ) - in a first sub-step for the respective printing element ( 102.3 ) from the pressure element ( 102.3 ) in the previous feeding step, amount of electric energy of heating and the heat capacity of the pressure element ( 102.3 ) a conditional by the amount of heating energy changed temperature of the pressure element ( 102.3 ) is calculated, In a second sub-step using the thermal model ( 108 ) for the pairs of adjacent model components, the changed temperature resulting from their mutual heat exchange is calculated in a predetermined time interval Δt and, in a third partial step, from the changed temperature of the pressure elements ( 102.3 ) the required amount of heating energy is determined. Method according to claim 9, characterized in that - in the third step for a printing element ( 102.3 ), which in the immediately following feeding step is not intended to generate a pixel of the printed image but is intended to generate a pixel of the printed image again in a subsequent subsequent feeding step, a pre-pulse energy quantity is determined, wherein - the pre-pulse energy is less than the required amount of heating energy. Method according to claim 9 or 10, characterized in that - the thermal model ( 108 ) as model components a plurality of to the printing elements ( 102.3 ) adjacent glaze wall elements ( 102.5 ) of the printhead ( 102.1 ), in the third substep from the changed temperature of the glaze wall elements ( 102.5 ) for the adjacent printing elements ( 102.3 ) a residual heat value Hy is determined and - in the third substep the required amount of heating energy for the respective pressure element ( 102.3 ) using the assigned residual heat value Hy and the number P of the pressure element ( 102.3 ) is determined immediately following in sequence to be generated pixels. A method according to claim 11, characterized in that - the residual heat value Hy for the image length of one without electrical energy supply to the pressure element ( 102.3 ) is representative in the feed direction generated print image and - the required amount of heating energy for the respective pressure element ( 102.3 ) is reduced if the image length corresponding to the residual heat value Hy is greater than the image length measured in the feed direction by the printing element ( 102.3 ), in particular provided that the required amount of heating energy is set to zero, if the image length corresponding to the residual heat value Hy is greater by at least the nominal image length of a pixel to be generated than the image length measured in the feed direction through the pressure element ( 102.3 ) immediately following in sequence to be generated pixels. Method according to one of the preceding claims, characterized in that - the required amount of heating energy is determined as a function of the position of the pixel in the printed image to be generated, wherein - the printed image is in particular a barcode, in particular a two-dimensional barcode ( 104.2 ). Method according to claim 13, characterized in that - the barcode ( 104.2 ) a two-dimensional barcode with a plurality of matrix-like arranged printed and non-printed barcode modules ( 104.6 ), wherein - a printed bar code module ( 104.6 ) comprises in each case a plurality of pixels and a first pixel comprises a part of a barcode module ( 104.6 ), and - the pressure element ( 102.3 ) for the first pixel in the feeding step ( 106.9 ) amount of heating energy to be supplied in the determining step ( 106.11 ) depending on the position of the bar code module ( 104.6 ) in the barcode ( 104.2 ) is determined. A method according to claim 14, characterized in that - the pressure element ( 102.3 ) for the first pixel in the feeding step ( 106.12 ) amount of heating energy to be supplied in the determining step ( 106.11 ) is determined as a function of the printing status of predetermined neighbor barcode modules, wherein - the predetermined neighbor barcode modules are assigned to the barcode module ( 104.6 ) and the printing status of the respective neighboring barcode module shows whether it is a printed or a non-printed barcode module. A method according to claim 15, characterized in that - which the respective pressure element ( 102.3 ) in the respective feeding step ( 106.12 ) to be supplied amount of heating energy for the pixels of a bar code module ( 104.6 ) using an energy template ( 107.1 . 107.2 ), wherein - for each print status constellation of the given neighboring bar code modules at least one separate En pouring template ( 107.1 . 107.2 ) is provided. Method according to one of claims 13 to 17, characterized in that - the barcode ( 104.2 ) a two-dimensional barcode with a plurality of matrix-like arranged printed and non-printed barcode modules ( 104.6 ) and - the thermal model as model components a plurality of to the printing elements ( 102.3 ) adjacent glaze wall elements ( 102.5 ) of the printhead ( 102.1 ), wherein - the glaze wall elements ( 102.5 ) on the bar code modules ( 104.6 ) are aligned. Method according to one of the preceding claims, characterized in that the thermal model ( 108 ) is a two-dimensional model. Method according to one of the preceding claims, characterized in that for a plurality of feed steps ( 106.12 ), in particular for all the feeding steps required to produce the printed image ( 106.12 ), a corresponding number of investigation steps ( 106.11 ) be performed. Method according to claim 19, characterized in that - the determination steps ( 106.11 ) are performed in advance for invariant areas of the print image, wherein - in particular for invariant areas of the print image, the determination steps ( 106.11 ) in advance for several print images. Printer with - a thermo-transfer printing device ( 102 ), which has a print head ( 102.1 ) with several printing elements ( 102.3 ), one with the print head ( 102.1 ) connected processing unit ( 101.4 ) for driving the print head ( 102.1 ) and one with the processing unit ( 101.4 ) connectable memory ( 101.5 ), and - a print head ( 102.1 ) associated color carrier device ( 103 ), the processing unit ( 101.4 ) is adapted, in a determination step ( 106.11 ) for the respective printing element ( 102.3 ) to determine a required amount of electrical heating energy corresponding to the pressure element ( 102.3 ) is to supply color from a the printhead ( 102.1 ) associated color carrier device ( 103 ) on one of the color carrier device ( 103 ) associated substrate ( 104 ) to generate a pixel of a printed image, - the processing unit ( 101.4 ) is adapted, in a feeding step ( 106.12 ) in the determination step ( 106.11 ) determined amount of heating energy the respective pressure element ( 102.3 ), and - the processing unit ( 101.4 ) is adapted to determine the amount of heating energy in the determining step ( 106.11 ) using at least a part of the memory ( 101.5 ) stored thermal model ( 108 ) of the printhead ( 102.1 ), characterized in that - the thermal model ( 108 ) as model components the printing elements ( 102.3 ), the color carrier device ( 103 ) and at least one of the printing elements ( 102.3 ) adjacent element ( 102.5 . 102.7 . 102.9 ) of the printhead ( 102.1 ), wherein - the thermal model ( 108 ) for pairs of adjacent model components defines a heat exchange variable characterizing the heat exchange between the two model components, - the processing unit ( 101.4 ) is adapted, using the heat exchange variables and the heat energy input into the pressure elements ( 102.3 ) in a previous feeding step for the model components a changed temperature of the printing elements ( 102.3 ) and - the processing unit ( 101.4 ) is adapted from the changed temperature of the printing elements ( 102.3 ) to determine the required amount of heating energy. Printer according to Claim 21, characterized that the heat exchange quantity has a thermal conductivity is. Printer according to claim 21 or 22, characterized in that the thermal model ( 108 ) - for pairs of adjacent model components having a flat contact area, defines a non-zero heat exchange variable and / or - defines a heat exchange variable equal to zero for pairs of adjacent model components that do not have a planar contact area. Printer according to one of Claims 21 to 23, characterized in that the thermal model ( 108 ) for pairs of adjacent printing elements ( 102.3 ) no heat exchange quantity or heat Exchange size equal to zero defined. Printer according to one of Claims 21 to 24, characterized in that the thermal model ( 108 ) as model components a plurality of to the printing elements ( 102.3 ) adjacent glaze wall elements ( 102.5 ) of the printhead ( 102.1 ). Printer according to claim 25, characterized in that the thermal model ( 108 ) as model components a plurality of the glaze wall elements ( 102.5 ) adjacent ceramic substrate elements ( 102.7 ). Printer according to claim 26, characterized in that - the thermal model ( 108 ) as a model component at least one heat sink ( 102.9 ), wherein - the thermal model ( 108 ) in particular for the heat sink ( 102.9 ) defines an infinitely high heat capacity and / or a constant temperature. Printer according to one of Claims 21 to 27, characterized in that the thermal model ( 108 ) for the color carrier device ( 103 ) defines an infinitely high heat capacity and / or a constant temperature. Printer according to one of Claims 21 to 28, characterized in that the processing unit ( 101.4 ) is adapted, in the determining step ( 106.11 ) - in a first sub-step for the respective printing element ( 102.3 ) from the pressure element ( 102.3 ) in the previous feeding step, amount of electric energy of heating and the heat capacity of the pressure element ( 102.3 ) a conditional by the amount of heating energy changed temperature of the pressure element ( 102.3 ) in a second sub-step using the thermal model ( 108 ) for the pairs of adjacent model components to calculate the changed temperature resulting from their mutual heat exchange in a predetermined time interval Δt and, in a third substep, from the changed temperature of the pressure elements ( 102.3 ) to determine the required amount of heating energy. Printer according to claim 29, characterized in that the processing unit ( 101.4 ) is designed to - in the third sub-step for a printing element ( 102.3 ), which in the immediately following feed step is not intended to generate a pixel of the print image but in another subsequent feed step should again generate a pixel of the print image, to determine a pre-pulse energy amount, wherein - the pre-pulse energy is less than the required amount of heating energy. Printer according to claim 29 or 30, characterized in that - the thermal model ( 108 ) as model components a plurality of to the printing elements ( 102.3 ) adjacent glaze wall elements ( 102.5 ) of the printhead ( 102.1 ), - the processing unit ( 101.4 ) is adapted, in the third sub-step from the changed temperature of the glaze wall elements ( 102.5 ) for the adjacent printing elements ( 102.3 ) to determine a residual heat value Hy and - the processing unit ( 101.4 ) is designed, in the third sub-step, the required amount of heating energy for the respective pressure element ( 102.3 ) using the assigned residual heat value Hy and the number P of the pressure element ( 102.3 ) to determine immediately afterwards in sequence to be generated pixels. Printer according to claim 31, characterized in that - the residual heat value Hy for the image length of the without electric power supply to the pressure element ( 102.3 ) is printed in the feed direction, and - the processing unit ( 101.4 ) is adapted to the required amount of heating energy for the respective pressure element ( 102.3 ), if the image length corresponding to the residual heat value Hy is greater than the image length measured in the feed direction by the printing element ( 102.3 ) pixels to be produced immediately following each other in sequence, wherein - the processing unit ( 101.4 ) is in particular configured to set the required amount of heating energy to the value zero if the image length corresponding to the residual heat value Hy is greater by the nominal image length of a pixel to be generated than the image length measured in the feed direction by the printing element ( 102.3 ) immediately following in sequence to be generated pixels. Printer according to one of claims 21 to 32, characterized in that - the processing unit ( 101.4 ) is designed to determine the required amount of heating energy as a function of the position of the pixel in the printed image to be generated, wherein - the printed image in particular a barcode ( 104.2 ), in particular a two-dimensional barcode. Printer according to claim 33, characterized in that - the barcode ( 104.2 ) a two-dimensional barcode with a plurality of matrix-like arranged printed and non-printed barcode modules ( 104.6 ), wherein - a printed bar code module ( 104.6 ) comprises in each case a plurality of pixels and a first pixel comprises a part of a barcode module ( 104.6 ), and - the processing unit ( 101.4 ) is adapted to the pressure element ( 102.3 ) for the first pixel in the feeding step ( 106.9 ) amount of heating energy to be supplied in the determining step ( 106.11 ) depending on the position of the bar code module ( 104.6 ) in the barcode ( 104.2 ) to investigate. Printer according to claim 34, characterized in that - the processing unit ( 101.4 ) is adapted to the pressure element ( 102.3 ) for the first pixel in the feeding step ( 106.12 ) amount of heating energy to be supplied in the determining step ( 106.11 ) in dependence on the printing status of predefined neighboring barcode modules, wherein - the predetermined neighbor barcode modules belong to the barcode module ( 104.6 ) and the printing status of the respective neighboring barcode module shows whether it is a printed or a non-printed barcode module. Printer according to claim 35, characterized in that - the processing unit ( 101.4 ) is adapted to the respective pressure element ( 102.3 ) in the respective supply step to be supplied amount of heating energy for the pixels of a bar code module ( 104.6 ) using an energy template ( 107.1 ), wherein - for each print status constellation of the given neighboring bar code modules at least one separate energy template ( 107.1 ) is provided. Printer according to one of Claims 33 to 37, characterized in that - the barcode ( 104.2 ) a two-dimensional barcode with a plurality of matrix-like arranged printed and non-printed barcode modules ( 104.6 ) and - the thermal model ( 108 ) as model components a plurality of to the printing elements ( 102.3 ) adjacent glaze wall elements ( 102.5 ) of the printhead ( 102.1 ), wherein - the glaze wall elements ( 102.5 ) on the bar code modules ( 104.6 ) are aligned. Printer according to one of Claims 21 to 37, characterized in that the thermal model ( 108 ) is a two-dimensional model. Printer according to one of Claims 21 to 38, characterized in that the processing unit ( 101.4 ) is adapted for a plurality of supply steps ( 106.12 ), in particular for all the feeding steps required to produce the printed image ( 106.12 ), a corresponding number of investigation steps ( 106.11 ). Printer according to claim 39, characterized in that - the processing unit ( 101.4 ) is adapted to perform the investigative steps ( 106.11 ) in advance for invariant areas of the printed image, wherein - the processing unit ( 101.4 ) is designed in particular for invariant areas of the printed image, the determination steps ( 106.11 ) in advance for several print images. Printer according to one of claims 21 to 40, characterized in that - the thermal model ( 108 ) for the color carrier device ( 103 ) and adjacent model components, the heat exchange between the ink carrier device ( 103 ) and the heat exchange variable characterizing the neighboring model components, - the ink carrier device defines a further memory ( 103.4 ), in which a for the heat exchange between the ink carrier device ( 103 ) and neighboring model components characterizing model parameters, and - the processing unit ( 101.4 ) is designed to complete the thermal model ( 108 ) the model parameter from the further memory ( 103.4 ) of the color carrier device ( 103 ) and to Er tion of the heat exchange between the ink carrier device ( 103 ) and the heat exchange variable characterizing the adjacent model components. Printer according to one of Claims 21 to 41, characterized in that it is in the form of a printer unit of a franking machine ( 101 ) is trained. Postage meter machine with a printer ( 102 ) according to any one of claims 21 to 41. Ink carrier device, in particular ink ribbon cassette, for a printer ( 102 ) according to one of claims 21 to 42, characterized by a memory ( 103.4 ), in which one for the heat exchange between the ink carrier device ( 103 ) and adjacent components of the printer ( 102 ) characterizing model parameter is stored. Color carrier device according to claim 44, characterized in that in the memory ( 103.4 ) at least one energy template ( 107.1 ) and / or a phase length function is stored, which corresponds to the respective pressure element ( 102.3 ) in the respective supply step to be supplied amount of heating energy for the pixels of a bar code module ( 104.6 Characterized.