EP4023448A1 - Method for generating control data for multicolour thermal direct printing - Google Patents

Abstract

The present invention relates to a method for creating control data for operating a direct thermal printer for printing on direct thermal printing paper, wherein a plurality of colors are formed in the direct thermal printing paper during printing.

Description

The present invention relates to a method for creating control data for multi-color, in particular two-color, direct thermal printing.

Direct thermal printing papers that change color to different colors in response to different temperatures are known to those skilled in the art. For example, the direct thermal printing paper KLRB 46B from the company Kanzan is a paper which turns red at a temperature of 75°C to 80°C and turns black at a temperature of 95°C to 105°C.

the EP1866161B1 also shows a two-color direct thermal printing paper. the EP1866161B1 also shows a printer for printing on such direct thermal printing paper, which comprises two print heads, the first print head applying a temperature to the direct thermal printing paper that triggers discoloration in the first color and the second print head applying a temperature to the direct thermal printing paper applied, which triggers a discoloration in the second color. From the EP3175993B1 a direct thermal printing paper is known which can be used for three-color printing.

Direct thermal printers with a print head whose thermocouples can generate two different temperatures are known to those skilled in the art DE60207488T2 and the DE60036515T2 known. In this way, a two-color print can be produced on the thermal direct printing paper. These printheads and their controls are expensive and complex.

The object of the invention is to enable more cost-effective multi-color direct thermal printing.

This object is achieved by a method according to claim 1, a data processing device according to claim 14 and a direct thermal printer according to claim 15.

• Empfangen von Bilddaten eines Originalbildes, das mindestens eine erste Farbe und eine zweite Farbe aufweist. Das ist ein Bild, das vorgegeben wird und das durch den Thermodirekt-Drucker gedruckt werden soll. Dabei ist dem Fachmann klar, dass der Thermodirekt-Drucker eine möglichst genaue Kopie der Originalvorlage herstellen soll, die aber nicht notwendigerweise exakt gleich aussehen muss. Ist das Originalbild als vorbreitete Grafik vorhanden, zum Beispiel in einer Bilddatei, so wird das Originalbild im Verfahren über eine Empfängervorrichtung zum Empfang von Daten empfangen. Das Originalbild kann jedoch auch an einer Datenverarbeitungsvorrichtung erstellt werden, auf der das Verfahren ausgeführt wird. Dann werden über eine Ein-/Ausgabevorrichtung Steuerbefehle von einem Bediener empfangen, die eine Anordnung von Texten, Grafiken, Farben usw. repräsentieren und das Originalbild wird auf diese Weise empfangen.
• Mit einer Steuervorrichtung werden Steuerdaten für einen Thermodirekt-Drucker erstellt. Die Steuerdaten sind zum zweifarbigen Druck eines Druckbilds geeignet. Der zweifarbige Druck des Druckbildes besteht aus der ersten Farbe und aus der zweiten Farbe. Die Steuerdaten umfassen mehrere Druckzeilen. Für jede Druckzeile ist in den Steuerdaten hinterlegt, welche Wärmequellen des Druckkopfes auf die Drucktemperatur erhitzt werden und welche Wärmequellen des Druckkopfes nicht erhitzt werden.

According to the invention, a method for creating control data for operating a direct thermal printer for printing direct thermal printing paper is proposed. The direct thermal printing paper comprises at least one thermoreactive layer. At least two colors can be formed with the at least one thermoreactive layer. Upon application of a first temperature, that is, upon heating a spot on the direct thermal paper to a first temperature, a first color is formed. Upon application of a second temperature, a second color is formed. The second temperature is higher than the first temperature. The direct thermal paper is moved by the direct thermal printer along a paper path from a paper pick-up to a paper output. The direct thermal printer also includes a print head, which includes heat sources that are arranged next to one another transversely to the paper path and that can be controlled electrically. In one embodiment, the heat sources are electrical resistances that heat up when current flows. The heat sources apply heat to the direct thermal printing paper at specific points. The procedure includes the following steps:

• receiving image data of an original image having at least a first color and a second color. This is an image that is specified and to be printed by the direct thermal printer. It is clear to the person skilled in the art that the direct thermal printer should produce a copy of the original template that is as accurate as possible, but that it does not necessarily have to look exactly the same. If the original image is available as a prepared graphic, for example in an image file, the original image is received in the method via a receiver device for receiving data. However, the original image can also be created on a data processing device on which the method is carried out. Then, via an I/O device, control commands are received from an operator representing an arrangement of text, graphics, color, etc., and the original image is thus rendered receive.
• Control data for a direct thermal printer are created with a control device. The control data are suitable for two-color printing of a print image. The two-color print of the print image consists of the first color and the second color. The control data includes several print lines. For each print line, the control data stores which heat sources of the print head are heated to the printing temperature and which heat sources of the print head are not heated.

The thermal direct printing paper is continuously fed past the print head and printed one line after the other. Thus, the control data for the print lines are control data that are sent one after the other to the print head, and the heat sources are correspondingly re-activated at intervals and heated or not heated to the printing temperature.

In one embodiment, the control data causes a plurality of adjacent heat sources to be heated to the printing temperature at the locations where the second color is to be formed on the direct thermal printing paper. At the locations where the first color is to be formed on the direct thermal printing paper, the control data from a plurality of adjacent heat sources causes one portion to be heated to the printing temperature and the other portion of the heat sources not to be heated.

Those skilled in the art understand that multiple adjacent heat sources can be adjacent heat sources in both row direction and column direction. Heat sources that are adjacent in the row direction are heat sources that are arranged next to one another on the print head. Heat sources that border one another in the direction of the columns is always the same heat source in the print head, but it is controlled line by line and thus in chronological succession. Even if it is only one from a hardware point of view If the heat source is heat, the heat source is directed to print pixels arranged next to one another in the column direction as a result of the line-by-line feed and printing of the direct thermal printing paper.

• Identifizieren von Flächen in der ersten Farbe und von Flächen in der zweiten Farbe in den Bilddaten. Dieser Schritt wird von der Steuervorrichtung ausgeführt. In einer Ausführungsform sind die Flächen definiert über die X-Koordinaten und Y-Koordinaten der die Flächen bildenden Punkte.
• Erstellen eines zweidimensionalen Steuermusters, wobei die Flächen der Bilddaten in der zweiten Farbe im Steuermuster mit aktiven Druckpixeln abgebildet werden. In einer Ausführungsform ist die zweite Farbe schwarz und zum Bedrucken des Thermodirektdruck-Papiers in schwarz ist die höhere Temperatur notwendig. Aus diesem Grund sind alle Wärmequellen, an denen sich die Fläche während des Drucks vorbeibewegt auf die Drucktemperatur erhitzt. Dieser Schritt wird von der Steuervorrichtung ausgeführt.
• Erstellen eines zweidimensionalen Steuermusters, wobei die Flächen der Bilddaten in der ersten Farbe im Steuermuster mit einem regelmäßigen Raster aus aktiven und passiven Druckpixeln abgebildet werden. In einer Ausführungsform ist die erste Farbe rot und zum Bedrucken des Thermodirektdruck-Papiers in rot ist die niedrigere Temperatur notwendig. Aus diesem Grund sind von den Wärmequellen, an denen sich die Fläche während des Drucks vorbeibewegt, manche auf die Drucktemperatur erhitzt und andere sind nicht erhitzt. Dieser Schritt wird von der Steuervorrichtung ausgeführt.
• Umwandeln des Steuermusters in Steuerdaten indem aus dem Steuermuster die aktiven und passiven Druckpixel zeilenweise in Steuerdaten für die Wärmequellen umgewandelt werden. Dieser Schritt wird von der Steuervorrichtung ausgeführt. Aktive Druckpixel heißt, dass die entsprechende Wärmequelle auf die Drucktemperatur erhitzt wird. Passive Druckpixel heißt, dass die entsprechende Wärmequelle nicht erhitzt wird.

In one embodiment, the method for creating control data includes the steps:

• identifying areas of the first color and areas of the second color in the image data. This step is performed by the controller. In one embodiment, the areas are defined via the x-coordinates and y-coordinates of the points forming the areas.
• Creating a two-dimensional control pattern, mapping the areas of the image data in the second color in the control pattern with active print pixels. In one embodiment, the second color is black and the higher temperature is necessary for printing the direct thermal printing paper in black. For this reason, all heat sources that the surface moves past during printing are heated to the printing temperature. This step is performed by the controller.
• Creation of a two-dimensional control pattern, where the areas of the image data in the first color in the control pattern are mapped with a regular grid of active and passive print pixels. In one embodiment, the first color is red and the lower temperature is necessary for printing the direct thermal printing paper in red. For this reason, of the heat sources that the surface moves past during printing, some are heated to the printing temperature and others are not. This step is performed by the controller.
• Converting the control pattern into control data by converting the active and passive print pixels line by line into control data for the heat sources from the control pattern. This step is performed by the controller. Active print pixels means that the corresponding heat source on the Printing temperature is heated. Passive print pixels means that the corresponding heat source is not heated.

If the original image is entered via the input/output device and includes, for example, text in black letters and text in red letters, it is already clear from the input which areas, namely the areas covered by the text, are in which color are present in the image data. For example, if the original image is a graphic received electronically by the receiving device, an image recognition algorithm must be applied to identify the first color areas and the second color areas.

In one embodiment, the regular raster is a raster which is repeated in rows and/or columns or arranged at an angle.

In one embodiment, areas of the first color in the image data are mapped in different regular grids due to their brightness in the control pattern. Dark first color areas include more active print pixels in the control pattern than light first color areas. This is the case when the second color is black. With more active print pixels, there is a higher proportion of black pixels in direct thermal printing and the area of the first color appears darker to the human eye.

In one embodiment, at least parts of the active print pixels have a minimum spacing in the control pattern for areas that exceed a certain brightness. The minimum distance is selected in such a way that the first color, the second color and the paper color overlap on the thermal direct printing paper. In other words, the print pixels are arranged so far apart that an unprinted area remains between two areas printed by the print pixels on the direct thermal paper, and thus an area in the paper color, in particular a white area. By a suitable choice of the distance between two Print pixel, a white pixel can be included in the print and the brightness of the printed area increases.

In one embodiment, a plurality of print pixels arranged in a regular grid, in particular a plurality of groups of adjacent print pixels arranged in a regular grid, are inactive print pixels in the control pattern for brightening an area in the second color. All other print pixels in the area are active print pixels. An area of the second color includes only active print pixels. Inserting groups of inactive print pixels in a regular grid creates white areas that lighten the second color. However, the white areas are outlined with a narrow border of the first color. If the second color is black and the first color is red, then gray scale printing is possible with such a control pattern, where the gray scale printing will have a slight red cast.

In one embodiment, the input/output device includes a display on which a graphical user interface is shown. The input/output device is designed to receive inputs for creating a label layout, the inputs including characters, standard graphics, colors, sizes, alignments and/or positions. The control device is designed to display the print image resulting from the created control data on the input/output device. In one embodiment, the control device is designed to compare the print image resulting from the created control data with the original image on the input/output device.

In one embodiment, the control device includes an object recognition device that recognizes at least one barcode in the image data from an original image received via the input/output device or receiving device. The control device outputs an error message via the input/output device if the barcode does not have the second color and/or is not aligned in a printing direction is. A barcode is particularly easy to read when it is printed in black and when the bars of the barcode are printed along the printing direction.

• Ermitteln von Flächen, die eine Farbe und eine Helligkeit aufweisen, wobei die Farben der Fläche mindestens der ersten Farbe, der zweiten Farbe, weiß oder einer Überlagerung davon entsprechen.
• Ermitteln eines Rasters aus aktiven und inaktiven Druckpixeln für die einzelnen Flächen.

In one embodiment, the control device performs the steps for the image data from an original image received by the receiving device:

• determining areas having a color and a lightness, the colors of the area being at least one of the first color, the second color, white, or an overlay thereof.
• Obtain a grid of active and inactive print pixels for each area.

This has the advantage that areas that look the same in terms of color and brightness are identified in an original image. Separate grids of active and inactive print pixels are then determined for these areas.

• Rendern der Bilddaten in Punkte von einer Größe von mindestens 9 oder 25 Druckpixeln.
• Bestimmen einer Farbe und einer Helligkeit für jeden Punkt.
• Bestimmen von Steuerdaten für jeden Punkt, wobei aus der Farbe und der Helligkeit jedes Punktes, aktive und inaktive Druckpixel für diesen Punkt abgeleitet werden.

In one embodiment, the control device performs the steps for the image data from an original image received by the receiving device:

• Rendering the image data into dots of at least 9 or 25 print pixels in size.
• Determining a color and a brightness for each point.
• determining control data for each dot, deriving from each dot's color and lightness, active and inactive print pixels for that dot.

• Mit einer Transportwalze wird das Thermodirektdruck-Papier zeilenweise entlang einer Druckrichtung bewegt. Dabei passiert das Thermodirektdruck-Papier den Druckkopf. In einer Ausführungsform wird das Thermodirektdruck-Papier fortlaufend, das heißt ohne Halt, bewegt. In einer Ausführungsform wird das Thermodirektdruck-Papier schrittweise bewegt. In einer Ausführungsform ist die Bewegungsgeschwindigkeit, das heißt die Transportgeschwindigkeit des Thermodirektdruck-Papiers zwischen 50 mm/s und 400 mm/s, insbesondere zwischen 100 mm/s und 200 mm/s.
• In jeder Zeile des Thermodirektdruck-Papiers werden ausgewählte Wärmequellen des Druckkopfes aufgrund der Steuerdaten elektrisch aufgeheizt. Es ist natürlich auch möglich, dass Zeilen vorhanden sind, in denen keine Wärmequellen aufgeheizt werden, weil in diesen Zeilen keine gedruckten Pixel vorhanden sind. An den Stellen, an denen das Thermodirektdruck-Papier die zweite Farbe ausbilden soll, werden mehrere aneinandergrenzende Wärmequellen auf eine Drucktemperatur erhitzt. An den Stellen, an denen das Thermodirektdruck-Papier die erste Farbe ausbilden soll, werden von mehreren aneinandergrenzenden Wärmequellen ein Anteil auf die Drucktemperatur erhitzt und der andere Anteil der Wärmequellen wird nicht erhitzt.

A method for printing the direct thermal print paper with a direct thermal printer and the control data comprises the following steps:

• The direct thermal printing paper is moved line by line along a printing direction with a transport roller. The thermal direct printing paper passes the print head. In one embodiment, the direct thermal printing paper is moved continuously, ie without stopping. In one embodiment, the direct thermal printing paper is stepped. In one embodiment, the movement speed, ie the transport speed of the direct thermal printing paper is between 50 mm/s and 400 mm/s, in particular between 100 mm/s and 200 mm/s.
• In each line of the direct thermal printing paper, selected heat sources of the print head are electrically heated based on the control data. It is of course also possible that there are rows in which no heat sources are heated because there are no printed pixels in these rows. At the points where the direct thermal printing paper is to form the second color, several adjacent heat sources are heated to a printing temperature. At the points where the direct thermal printing paper is to form the first color, a proportion of several adjacent heat sources are heated to the printing temperature and the other proportion of the heat sources is not heated.

The two-color direct thermal printing paper, in particular the Kanzan paper already mentioned, turns red in a first temperature range of 75°C to 80°C and black at a temperature of 95°C to 105°C when heat is applied. Since the paper slides under the print head and the heat sources are covered with a protective layer or glass, for example, and the paper as linerless paper has a protective layer, in particular silicone layer, over the thermoreactive one, the heat sources during printing may have to be slightly higher temperatures than those above mentioned discoloration temperatures. The direct thermal printing paper is intended to be supplied with two discrete temperatures for two-color printing. However, direct thermal printheads, whose heat sources can generate two different temperatures, are technically complex and sometimes unreliable. The advantage of this process is that only one discrete temperature, the printing temperature, has to be generated at the heat sources. If several adjacent pixels are heated to the printing temperature, the printing temperature and that is transferred Direct thermal paper below these pixels heats up to the higher temperature range where the second color is formed. If, from a group of adjacent heat sources, i.e. from a group of adjacent pixels, some are heated to the printing temperature and others are not, an average temperature is formed that is transferred to the direct thermal printing paper, which is in the lower temperature range of direct thermal printing paper falls and forms the first color. It can be observed that the active heat sources, i.e. the heat sources heated to the printing temperature, form pixels in the second color on the direct thermal printing paper. In the vicinity of these pixels in the second color, spots in the first color form because the temperature on the thermal direct printing paper in these areas drops somewhat and corresponds to the lower temperature range. The process makes use of the fact that a point heat source radiates heat in the immediate vicinity. A combination of active and inactive heat sources creates a pixel pattern on the direct thermal printing paper that has a few pixels in the second color and around them pixels in the first color. Due to the small pixel size, however, the human eye cannot perceive the individual pixels. Rather, depending on the relationship between active and inactive heat sources and their geometric arrangement, the area appears as an area in the first color.

Those skilled in the art understand that the unprinted direct thermal printing paper is usually white or has a whitish tint. This is not to be understood as a first or second color within the meaning of the invention.

In one embodiment, the second color is black. In one embodiment, the first color is red. The person skilled in the art understands that the first color and the second color mean a reaction of the thermoreactive layer. At the pixel to which heat is applied, the color changes thermoreactive layer. By combining different pixels of the first color with the second color and with the light, in particular white, color of the unprinted paper, color effects can be achieved, such as a light red area or a dark red area. However, these consist of individual red, white and black pixels and are not to be regarded as separate colors within the meaning of this disclosure.

In one embodiment, the printing temperature is equal to or higher than the second temperature. The heat source must transfer heat to the paper at the temperature of the higher temperature range. This is the second temperature. Due to the effects that can occur due to the protective layer on the print head and the protective layer on the direct thermal printing paper, the printing temperature may have to be slightly higher than the second temperature.

In one embodiment, the step of moving the direct thermal printing paper line by line occurs during a line time from a line n to a next line n+1. In one embodiment, the movement of the direct thermal printing paper is continuous, ie the paper is moved past the print head at a constant or almost constant speed. In one embodiment, the movement of the direct thermal paper is stepped, that is, the direct thermal paper is moved to the next line n+1 and stopped until the line time expires, and then moved to line n+2.

In one embodiment, when printing an area, the area on the direct thermal printing paper comprises multiple rows and multiple columns. The rows from the print head's point of view correspond to a time when this row is under the heat sources of the print head. The columns of the area correspond to certain heat sources of the print head as seen from the print head. If an area on the thermal direct printing paper is printed in the second color, then over the times that correspond to the lines of the area, all Heat sources corresponding to the columns of the rows heated to the printing temperature. All heat sources that correspond to the projection on the surface on the direct thermal printing paper are heated to the printing temperature and the surface changes color to the second color. In other words, to print an area on the direct thermal printing paper in the second color, the area including multiple rows (n, n+1, n+2) and multiple columns, while printing the multiple rows (n, n+ 1, n+2), all heat sources corresponding to the multiple columns heated to the printing temperature.

If, on the other hand, the surface is printed in the first color, one part of the heat sources mentioned in the previous paragraph must be heated to the printing temperature (active heat sources) and another part is not heated (inactive heat sources), i.e. the other Some of the heat sources are not controlled electrically. In other words, to print an area on the direct thermal printing paper in the first color, the area including multiple rows (n, n+1, n+2) and multiple columns, while printing the multiple rows (n, n+ 1, n+2) from the heat sources corresponding to the several columns, a proportion is heated to the printing temperature, so that the projection of the heat sources onto the surface corresponds to a regular grid of active and inactive heat sources, with as many or more inactive than active ones heat sources are present. As already explained above, a pure print in the first color, ie an area that only has pixels in the first color, is not possible with the method. However, the human eye perceives the area in the first color when the pixels of the first color and the pixels of the second color are arranged in a regular grid and the pixels of the first color predominate. Therefore, there must be as many or more inactive heat sources in the grid on the projection of the area than active heat sources.

In one embodiment, to print an area on the direct thermal paper in a color corresponding to an overlay of at least two of the first color, the second color, and the paper color, the area having multiple lines (n, n+1, n+ 2) and includes multiple columns, during the printing of the multiple rows (n, n+1, n+2), the heat sources corresponding to the multiple columns are heated to the printing temperature in such a way that the projection of the heat sources onto the surface has a regular Grid of active and inactive heat sources corresponds. The paper color is white, although the white can have a slight reddish tinge. If the grid is arranged in such a way that the distance between two heat sources that are heated to the printing temperature exceeds a minimum distance in row direction and column direction, a white pixel appears on the surface. It is thus possible to create a grid that represents an overlay of pixels in the first color, in the second color and white pixels. In one embodiment, the second color is black. Hues in the first color, particularly red, can be printed at different levels of lightness. A screen containing more active heat sources will print a darker shade of the first color on the direct thermal paper than a screen with fewer active heat sources. If, for example, the first color is red and the second color is black, red tones can be generated in different brightnesses by selecting the grid with white and black pixels, from a bright red with a large proportion of white to a dark red that goes black transforms. The fact that the printing of red pixels always causes a black pixel in the middle, which is surrounded by red pixels, means that there can be no pure red area and an area perceived by the human eye as a red area made up of a plurality of red pixels and a smaller number of black pixels and in particular also a smaller number of white pixels.

In one embodiment, the regular raster is a raster which is repeated in rows and/or columns or arranged obliquely or alternately. Different effects can be achieved with different regular grids and in particular different brightnesses of the first color can be printed. A repeating grid over several pixels in the row direction and in the column direction results in a small area with a specific lightness of the first color. Various geometric shapes can be assembled from many small areas, resulting in many shapes and a large degree of freedom for prints in the first and second color.

In one embodiment, the direct thermal printing paper is linerless paper. In one embodiment, the direct thermal printing paper comprises a silicone layer on the upper side. Linerless paper is paper made from a continuous strip that does not include a carrier tape. The paper layer on the back has an adhesive material, in particular an adhesive coating, in order to be able to stick labels that have been separated from the continuous strip to an object. So that the label web does not stick to itself when it is rolled up into a continuous roll, the top of the paper has a silicone layer from which the adhesive material can be removed. This silicone layer on the thermal direct printing paper has the advantage that the heat from the heat source is distributed somewhat in the silicone layer and not only penetrates the paper at certain points under the heat source, but also in its surroundings. Heat still penetrates the paper in the vicinity of the heat source, but at a slightly lower temperature. The effect that a heat source that is heated to the printing temperature produces a black pixel and red pixels appear around it is particularly pronounced with linerless paper. In addition to the properties of the silicone material, this effect is also caused by the fact that the thickness of the silicone layer ensures a distance between heat sources and heat sources thermoreactive layer ensures. This distance also leads to a certain spread of the heat under the heat source.

In one embodiment, an active heat source is electrically controlled by the controller during a printing interval. The pressure interval is divided into a saturation interval and a subsequent cooling interval. The saturation interval begins with a wait time. The heat source is only supplied with electricity in the time after the waiting time has elapsed until the end of the saturation interval. The waiting time in row n depends on the status of the heat source in at least one previous row n-1. In one embodiment, the print interval corresponds to line time. In one embodiment, the saturation interval is the same for all heat sources of the printhead. In one embodiment, the waiting time can be selected differently for each heat source and depends on the previous state of this heat source. For example, if a heat source in a previous line n-1 is heated to the printing temperature, it still has a certain amount of residual heat in the following line. If this heat source is to be heated up again to the printing temperature in this line n, then due to the residual heat, slightly less electricity is required than with a cold heat source. For this reason, no current is supplied during a waiting time. The power supply therefore does not take place over the entire saturation interval. Those skilled in the art know this control of the heat sources under the term history control. In one embodiment, the printhead includes a temperature sensor on its surface. Depending on the temperature of the temperature sensor, the saturation interval, which is the same for all heat sources, is determined. For example, a longer saturation interval is chosen in a very cold environment than in a warm environment.

According to the invention, a computer program with program code means is proposed to the method for creating control data for operating a direct thermal printer to perform printing on direct thermal paper when running the program on a computer or on a computer of a direct thermal printer.

According to the invention, a computer program product with program code means that are stored on a computer-readable data carrier is proposed in order to carry out the method for creating control data for operating a direct thermal printer for printing direct thermal printing paper if the computer program runs on a computer or on a computer of a direct thermal printer.

According to the invention, a data processing device is proposed with an input/output device, a control device, in particular a CPU, and a transceiver for sending and receiving data via a network. The control device executes a method for creating control data for operating a direct thermal printer for printing on direct thermal printing paper. The transceiver is designed to send the control data and/or the control pattern to a direct thermal printer via the network.

According to the invention, a direct thermal printer for printing direct thermal printing paper is proposed. The direct thermal printing paper comprises at least one thermoreactive layer. At least two colors can be formed with the at least one thermoreactive layer. A first color is formed upon application of a first temperature and a second color is formed upon application of a second temperature. The second temperature is higher than the first temperature. The direct thermal printer includes a transport roller that moves the direct thermal printing paper along a paper path from a paper input to a paper output. The direct thermal printer comprises a print head, which comprises heat sources which are arranged next to one another transversely to the paper path and can be controlled electrically. The printhead applies heat to the thermal direct printing paper at specific points. The direct thermal printer includes a control device that controls a rotation of the transport roller and uses the transport roller to move the direct thermal printing paper line by line along the print head in the direction of a printing direction. Each heat source of the print head is electrically connected to the controller and can be heated to a printing temperature. The control device executes a method for creating control data for operating a direct thermal printer for printing on direct thermal printing paper. The control device controls the heat sources with the control data.

In one embodiment, the control device is designed to heat selected heat sources of the print head to the printing temperature in each line of the direct thermal printing paper. A plurality of adjacent heat sources are heated to the printing temperature at the points where the second color is to be formed on the direct thermal printing paper. At the points where the first color is to be formed on the direct thermal printing paper, a portion is heated to the printing temperature by a plurality of adjacent heat sources and the other portion of the heat sources is not heated.

In one embodiment, the pressure bar is a pressure bar based on thick film technology. Examples of pressure bars based on thick film technology are the KD2004-DC91B from Rohm or the KPW-104-BZR from Kyocera. In one embodiment, the pressure bar is a pressure bar based on thin-film technology.

In one embodiment, the printing temperature is equal to or higher than the second temperature.

In one embodiment, the transport roller is a pressure roller that presses the direct thermal printing paper against the print head.

In one embodiment, the direct thermal printer is a linerless printer and the direct thermal printing paper is a continuous paper made of linerless paper, which is provided with a silicone layer on its upper side.

In one embodiment, the controller controls the transport roller so that the transport roller moves the direct thermal printing paper from a line n to a next line n+1 during a line time, the movement being stepwise or continuous during the line time.

Fig. 1

schematische Darstellung eines Thermodirekt-Druckers,

Fig. 2

schematische Darstellung eines Druckkopfes für einen Thermodirekt-Drucker,

Fig. 3

schematische Darstellung eines Temperaturverlaufs an einer Wärmequelle während eines Druckintervalls und Darstellung des durch die Steuervorrichtung angelegten Stromes an der Wärmequelle,

Fig. 4

schematische Darstellung eines Thermodirektdruck-Papiers für zweifarbigen Druck in einer ersten Ausführungsform,

Fig. 5

schematische Darstellung eines Thermodirektdruck-Papiers für zweifarbigen Druck in einer zweiten Ausführungsform,

Fig. 6-15

verschiedene Steuermuster zum zweifarbigen Thermodirektdruck und zugehörige Druckergebnisse, und

Fig. 16

schematische Darstellung eines Verfahrens zur Erstellung von Steuerdaten zum Betrieb eines Thermodirekt-Druckers.

Some embodiments of the invention are shown by way of example in the drawings and described below. They show, each in a schematic representation:

1

schematic representation of a direct thermal printer,

2

schematic representation of a print head for a direct thermal printer,

3

schematic representation of a temperature curve at a heat source during a printing interval and representation of the current applied by the control device to the heat source,

4

schematic representation of a thermal direct printing paper for two-color printing in a first embodiment,

figure 5

schematic representation of a thermal direct printing paper for two-color printing in a second embodiment,

Figures 6-15

various control patterns for two-color direct thermal printing and associated print results, and

16

Schematic representation of a method for creating control data for operating a direct thermal printer.

1 shows a direct thermal printer 30 in a schematic representation. The printer includes a paper path that leads from a paper receptacle 46, in which a paper roll 32 is mounted, via a print roller 40 and a print head 42 to a paper output 44. The paper is wound onto a paper roll 32 in the form of an endless strip of direct thermal printing paper 34 . The direct thermal printing paper 34 comprises an underside to which an adhesive layer is applied and an upper side 36 to which a silicone layer is applied. The pressure roller 40 serves as a transport roller for the continuous strip of direct thermal printing paper 34. The pressure roller presses the direct thermal printing paper 34 with its upper side 36 against the print head 42. The direct thermal printer 30 includes a control device 48 which is electrically connected to the print head 42 and the Pressure roller 40 is connected. The control device 48 controls the print roller 40, which moves the direct thermal printing paper 34 past the print head 42 line by line. The control device 48 also controls the print head 42, in particular the control device 48 controls the heat sources 52 of the print head 42, so that the desired print results in line n, which is located just below the print head 42 due to the transport of the direct thermal printing paper 34 . The coordinated control of the print roller 40 and the print head 42 by the control device 48 results in line-by-line printing on the thermal direct printing paper 34. The pixels in the column direction correspond to the individual heat sources 52, the pixels in the row direction n, n+1, n +2 correspond to the respective point in time t0, tz, 2tz at which the corresponding line n, n+1, n+2 is located under the print head 42. The controller 48 is configured to heat or not heat each individual heat source 52 to a printing temperature.

The control device 48 is also connected to a transceiver 49 . With the transceiver 49, the direct thermal printer 30 is connected to a transceiver 76 of a data processing device 70 via a network. The data processing device 70 includes an input/output device 72 with which an operator can operate the data processing device 70 . The operator can use the input/output device 72 to input image data of an original image that is to be printed by the direct thermal printer 30 into the data processing device 70 . The data processing device 70 includes a control device 74 which is designed to create control data. The control data is data for controlling the direct thermal printer 30. The control data is sent from the data processing device 70 via the transceiver 76 to the direct thermal printer. In one embodiment, the data processing device 70 is integrated into the direct thermal printer 30 .

2 shows a print head 42 in a view from below. On this side, the direct thermal paper 34 is moved past the print head 42 line by line along a printing direction 60 by the print roller 40 . The print head 42 comprises a print field 56 with a multiplicity of heat sources 52 arranged next to one another. The heat sources emit heat at specific points. There is a spacing 54 between the heat sources 52. The spacing 54 between the heat sources 52 is illustrated in FIG 2 presented relatively broadly. In practice, the distance 54 between two adjacent heat sources 52 is very small. It should in 2 only indicated that each heat source 52 is attached independently of the adjacent heat sources 52 and can be controlled separately by the control device. The width of the print field 56 corresponds at least to the maximum printable paper width. The pressure field 56 is covered with a cover that preferably conducts heat well, in order to protect the heat sources 52 from mechanical damage. The heat sources 52 are in particular heating resistors. The printhead 42 includes a temperature sensor 58 which measures the temperature 58 at the top of the print head and passes it on to the control device 48 as a parameter.

Typical values for the direct thermal paper width are 60 mm, 80 mm or 120 mm. A typical resolution of applicant's linerless direct thermal printing paper is 200 dpi, in particular 300 dpi. A typical printing speed, ie a typical transport speed at which the paper is moved along under the print head, is 100 mm/s to 400 mm/s, in particular 120 mm/s, 150 mm/s or 250 mm/s.

In order to achieve a resolution of 200 dpi, approx. 8 dots (∼pixels) per mm must be provided, i.e. 8 heat sources 52 per mm. In order to achieve a resolution of 300 dpi, approx. 12 dots (∼pixels) per mm must be provided, i.e. 12 heat sources 52 per mm. With a paper width of 80 mm, the print head comprises at least 960 heat sources 52.

With a resolution of 300 dpi, 12 dots/mm, i.e. 12 lines/mm, are required in the transport direction. At a typical transport speed, i.e. printing speed, of 150 mm/s, the printing roller has to do 1800 lines/s, i.e. 1800 steps per second.

3 shows a schematic diagram for the activation of a heat source 52 by the control device 48 (lower part) and the associated heat development at the heat source 52 (upper part). A pressure interval ti is shown. A line n of the direct thermal printing paper is printed during a printing interval ti. The print interval ti is typically at least 300 µs long. In any case, the print interval ti must not be longer than a line time tz and is in particular the same length as a line time tz. At the beginning of the printing interval, the direct thermal printing paper 34 has been moved by the platen roller 40 from line n-1 to line n. In the case of a step-by-step transport of the direct thermal printing paper 34, the direct thermal printing paper 34 is on line n at the beginning of the printing interval The print interval consists of a saturation interval ts during which the heat source 52 is energized by the controller 48. Furthermore, the pressure interval ti consists of a cooling interval ta following the saturation interval ts. If the print interval ti is shorter than the line time tz, then the direct thermal printing paper 34 is transported to the next line n+1 following the print interval ti and up to the end of the line time tz. If the print interval ti is the same length as the line time tz, then the direct thermal printing paper 34 is transported to the next line n+1 in the late part of the cooling interval ta and up to the end of the line time tz/print interval ti.

Depending on whether the heat source was energized in the previous row n-1 or in the previous rows n-1, n-2, n-3 or not, the saturation interval begins with a waiting time tw, tw', tw". After the waiting time tw, tw', tw", a current is applied to the heat source 52 by the control device 48. The heat source 52 begins to heat up to the printing temperature TD and maintains the printing temperature TD until the end of the saturation interval ts. The saturation interval ts is the same for all heat sources 52 of the print head, with the waiting time tw, tw', tw" being calculated separately for each heat source 52 of the print head on the basis of the preceding lines n-1, n-2, n-3 (History -Control). In the cooling interval ta, no current is applied to the heat source 52 by the control device 48 and the temperature at the heat source 52 falls to its initial value during this time. Based on the print head temperature determined by the temperature sensor 58 on the print head, the control device 48 determines the length of the saturation interval ts.

For the two-color direct thermal printing according to the method, a heat source is always heated to the printing temperature. The method does not include a first temperature for printing the first color and a second temperature for printing the second colors. In any case, the active heat sources 52 in one row are heated to the printing temperature TD. the other heat sources 52 are inactive heat sources 52 and are not heated.

4 shows a schematic representation of a direct thermal printing paper 34 for two-color printing in a first embodiment. A cross section of the direct thermal printing paper 34 is shown. The direct thermal printing paper comprises a paper layer 12. On the underside of the paper layer 12 is an adhesive layer 14, ie an adhesive layer applied. A first thermoreactive layer 22 is applied above the paper layer 12, which forms a first color, in particular red, when heat is applied. The first thermoreactive layer 22 turns red at a temperature of 70.degree. C. to 85.degree. C., in particular 75.degree. C. to 80.degree. A second thermoreactive layer 20 is applied to the first thermoreactive layer 22 and forms a second color, in particular black, when heat is applied. The second thermoreactive layer 20 turns black at a temperature of 90°C to 110°C, in particular 95°C to 105°C. A silicone layer 16 is applied above the second thermoreactive layer 20, which prevents the adhesive layer 14 from adhering and allows the adhesive layer 14 to detach when an endless strip of the direct thermal printing paper 34 is rolled up into a roll.

Both the first thermoresponsive layer 22 and the second thermoresponsive layer 20 are transparent when no heat is applied to them.

If a first temperature, in particular 75° C. to 80° C., is applied to the direct thermal printing paper 34, the first thermoreactive layer 22 turns red and the second thermoreactive layer 20 remains transparent. A red print appears. If the direct thermal printing paper 34 is supplied with a second temperature, the second temperature being higher than the first temperature, in particular 95° C. to 105° C., the first thermoreactive layer 22 turns red and the second thermoreactive layer 20 turns black. The second thermally responsive layer 20 covers the first thermally responsive layer 22 so that only the black color in the second thermally responsive layer 22 is visible. A black print is produced.

figure 5 shows a schematic representation of a direct thermal printing paper 34 for two-color printing in a second embodiment. Compared to 4 there is no separate first thermoresponsive layer and second thermoresponsive layer. A thermoreactive layer 18 is applied to the paper layer 12, which turns red when a first temperature is applied and turns black when a second temperature is applied.

Figures 6 to 15 show different control patterns for controlling the heat sources of the print head 42 (right graphic in landscape format) and the resulting printed image on direct thermal printing paper 34 (left graphic in landscape format). The control patterns form regular grids. The control data for the direct thermal printer are derived from the control patterns. The print head is controlled with the control data resulting from a line t0, tz, 2*tz of the control pattern at the points in time at which the corresponding line n, n+1, n+2 of the direct thermal printing paper is under the print head located. The drawings of the print head 42 each show 14 heat sources 52 lying next to one another, which are controlled by the control device 48 independently of one another, regularly and as a function of the line time. A 1 means an active heat source, i.e. the heat source 52 has a current and temperature profile as shown in 3 is shown schematically. A 0 indicates an inactive heat source 52, that is, there is no heat output from this heat source. The printed image on the direct thermal printing paper 34 is shown schematically. A black area in the drawings indicates a black pixel. A hatched area in the drawings indicates a red pixel. A white area indicates an unprinted, i.e. white, area on the direct thermal printing paper 34.

Figures 6 to 12 show 14 consecutive lines n, n+1, ..., n+13, which are printed at the times t=0, tz, 2*tz, ..., 13*tz, the times being the starting times of the Specify the pressure interval ti. Regular grids are shown in each case, which have been selected from a larger area. It is therefore a zoom view of an area that appears to be the same color. As shown above, a resolution of 300 dpi requires printing at around 12 dots/mm. That is, the in Figures 6 to 12 The fields shown have a size of approximately 1.16 mm * 1.16 mm (∼1.36 mm ² ₎ .

6 shows a control pattern with a high proportion of black dots. 75% of the heat sources are active. That is, only 25% of heat sources are inactive. A black color forms on the active heat sources, which is superimposed on the red color formed on the inactive heat sources. The area shown has a dark red tone due to the superimposition of the black and red colors. The human eye does not recognize the individual pixels, but only an area that forms this shade of red. Figures 7 to 12 each show areas that form different shades of red with different proportions of black pixels, red pixels and white pixels. In this case, individual heat sources in a row are activated by the control device. Under these heat sources, a black pixel is formed, red pixels are formed around it, and no discoloration of the white direct thermal printing paper takes place at a further distance. Different color effects can be achieved with different grids. For the human eye, red tones of different brightness are created.

Figures 13 to 15 do not show square print areas, but are extended by one or two lines to complete the display. No regular grids have been singled out that could be mentally extended beyond the edges of the drawings presented. Rather, closed forms are shown.

13 shows a square black dot of 4x4 pixels (0.3 mm * 0.3 mm at 300 dpi). At a high printing speed, the direct thermal printing paper is moved quickly under the print head by the platen roller. This in 3 The cooling interval ta shown is not large enough for the heat sources to have sufficiently cooled down at the point in time (6*tz, 7*tz ∼ lines n+6, n+7). Therefore, the red color runs on a bit and after the black pixels have been printed in the transport direction, not only the pixels of the next line but also the pixels of the next but one line are colored red. The same effect occurs in 14 on.

14 shows a section of a barcode consisting of two bars that is printed in black. The black bars are of different lengths. It is therefore the lower left edge of a barcode. The bars at the edge of the barcode are slightly longer than in the middle, since the number corresponding to the barcode is printed in the middle of the barcode. Due to the reaction of the direct thermal printing paper, it is advantageous to position the bars of a barcode lengthwise in the transport direction. The red feathering effect on the printed paper is therefore at the end of the bars and not distributed across the barcode. This makes it easier to scan the barcode.

15 shows schematically the printing of a number in black ink. The number contains very few pixels and would in reality be printed with significantly more black pixels. In reality, the proportion of red is negligible, so that the number printed in black only has a very thin red border that is barely visible to the human eye.

The drawings serve exclusively for the schematic representation to illustrate the invention. In order to depict individual geometric structures in a real size for a print, significantly more pixels must be used, which, however, cannot be shown here for reasons of clarity. If in reality more pixels are used to print a character, then the red component for a black character is significantly lower than in e.g 14 and 15 displayed and therefore not disturbing.

16 shows a schematic representation of a method for creating control data for a direct thermal printer. In step 100, the controller 74 of the computing device 70 receives input from an operator. The operator specifies image data of an original image, for example, by making a corresponding draft via the input/output device 72 . In step 102, the controller 74 identifies areas in the image data that are black and areas that are red. In step 104, control patterns in which all print pixels are active print pixels are created for the black areas. In step 106 the brightness of the red areas is determined. In step 108, a grid is defined for the red areas with a first lightness in order to print the red areas with the first lightness in the corresponding lightness. The control pattern for these areas with the corresponding active print pixels is derived from the raster. In step 110, a grid is defined for the red areas with a second brightness in order to print the red areas with the second brightness in the corresponding brightness. The control pattern for these areas with the corresponding active print pixels is derived from the raster. Steps analogous to steps 108, 110 are carried out for all further red areas with a different brightness. In step 112, the control patterns of the individual surfaces are connected and set a control pattern for printing. In step 114, the resulting printed image is shown to the operator with the input/output device for approval. If the operator releases the print image, then in step 116 the control data for the direct thermal printer are derived from the control patterns, ie the data for controlling the print head for each line n, n+1, n+2 are determined. In step 118 the control data are sent from the data processing device 70 to the direct thermal printer 30 via the transceiver 76 .

The functions of various elements shown in the drawings, including the function blocks, can be realized by dedicated hardware or by generic hardware capable of executing software associated with the corresponding software. If the functions are provided by a processor, they may be provided by a single dedicated processor, a single shared processor, or multiple generic processors, which in turn may be shared. The functions can be implemented, without limitation, by a digital signal processor (DSP), network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) with stored software, random access memory (RAM ), and non-volatile memory are made available.

Claims (15)

Method for creating control data for operating a direct thermal printer for printing direct thermal printing paper, the direct thermal printing paper comprising at least one thermoreactive layer, at least two colors being able to be formed in the at least one thermoreactive layer, the thermoreactive layer when a first temperature forms a first color, and upon application of a second temperature forms a second color, the second temperature being greater than the first temperature, the direct thermal printer including a print head positioned transversely to the paper path along a paper path from a paper input to a paper output comprises electrically controllable heat sources arranged next to one another, which selectively supply heat to the thermal direct printing paper that can be moved along the print head, the method comprising the following steps: - receive, via an input/output device or receiving device, image data of an original image which has at least a first color and a second color, - create, with a control device, control data for a direct thermal printer for two-color printing of a print image consisting of the first color and the second color, the control data comprising a plurality of print lines and for each print line for each heat source of the print head either the heating the heat source to a pressure temperature or no heating of the heat source. Method for creating control data according to claim 1, wherein at the positions where the second color is to be formed on the direct thermal printing paper, the Control data cause the heating of a plurality of adjacent heat sources to the printing temperature and, at the points where the first color is to be formed on the direct thermal printing paper, the control data of a plurality of adjacent heat sources cause one portion to be heated to the printing temperature and the other portion the heat sources do not cause any heating. Method for creating control data according to claim 1 or 2, the method comprising the steps of: - identify in the image data, with the control device, areas in the first color and areas in the second color, - creating, with the control device, a two-dimensional control pattern, wherein the areas of the image data in the second color are mapped in the control pattern with active print pixels and the areas of the image data in the first color are mapped with a regular grid of active and passive print pixels, and - convert, with the control device, the control pattern into control data by the active and passive print pixels being converted line by line into control data for the heat sources from the control pattern. Method for creating control data according to Claim 3, in which the regular grid is a grid which is repeated in rows and/or columns or is arranged at an angle. Method for creating control data according to claim 3 or 4, wherein in the control pattern areas of the first color in the image data are mapped into different regular grids due to their brightness, with dark areas in the first color in the control pattern in particular comprising more active print pixels than light areas in the first color. Method for creating control data according to one of Claims 3 to 5, wherein in the control pattern for areas which exceed a specific brightness, at least parts of the active print pixels have a minimum spacing, so that there is an overlay of the first color, the second color and the paper color on the direct thermal printing paper. Method for creating control data according to one of Claims 3 to 6, in which several, in particular several groups of adjacent printing pixels are inactive printing pixels for the brightening of an area in the second color in the control pattern for the area consisting of active printing pixels in a regular grid. Method for creating control data according to one of Claims 1 to 7, in which the input/output device comprises a display on which a graphical user interface is shown and in which the input/output device is designed to receive inputs for creating a label layout, the inputs include characters, standard graphics, colors, sizes, alignments and/or positions, the control device being designed to display the print image resulting from the created control data on the input/output device and in particular to compare it with the original image. Method for creating control data according to one of Claims 1 to 8, wherein the control device comprises an object recognition device which recognizes at least one barcode in the image data from an original image received via the input/output device or receiving device and outputs an error message if the barcode does not second color and/or not aligned in a printing direction. A method for preparing control data according to any one of claims 1 to 9, wherein the control device for the image data from an original image received by the receiving device performs the steps of: - determining areas having a color and a brightness, the colors of the area being at least one of the first color, the second color, white or a superposition thereof, and - determine a grid of active and inactive print pixels for the individual areas. A method for preparing control data according to any one of claims 1 to 10, wherein the control device for the image data from an original image received by the receiving device performs the steps of: - render the image data into dots with a size of at least 9 or 25 print pixels, - determine a color and a brightness for each point, and - determining control data for each dot, deriving from the color and brightness of each dot active and inactive print pixels for that dot. Computer program with program code means for carrying out the method according to one of Claims 1 to 11 when the program is run on a computer or on a computer of a direct thermal printer. Computer program product with program code means, which are stored on a computer-readable data carrier, in order to carry out the method according to one of Claims 1 to 11, when the computer program is run on a computer or on a computer of a direct thermal printer. Data processing device with an input/output device, a control device, in particular a CPU and a transmitting/receiving device for sending and receiving data via a network, the control device having a method for creating control data for operating a direct thermal printer for printing direct thermal printing Paper according to one of Claims 1 to 11 and the transceiver is designed to send the control data and/or the control pattern to a direct thermal printer via the network. Direct thermal printer for printing direct thermal printing paper, the direct thermal printing paper comprising at least one thermoreactive layer, at least two colors being able to be formed with the at least one thermoreactive layer, with a first color being applied when a first temperature is supplied and a first color being produced when a second temperature is supplied second color is formed, wherein the second temperature is higher than the first temperature, and with a transport roller that the direct thermal printing paper along a paper path of moved from a paper receptacle to a paper output, and with a print head, which comprises electrically controllable heat sources arranged next to one another transversely to the paper path and which supply heat to the direct thermal printing paper at specific points, the direct thermal printer comprising a control device which controls a rotation of the transport roller and with the transport roller moves the direct thermal printing paper line by line along the print head in the direction of a printing direction, wherein each heat source of the print head is electrically connected to the control device and can be heated to a printing temperature, and the control device includes a method for creating control data for operating a direct thermal printer for printing direct thermal printing paper according to one of Claims 1 to 11 and the control device controls the heat sources with the control data.

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