PRINT QUALITY OPTIMIZATION BASED ON REGIONS OF INTEREST

Description

FIELD OF THE INVENTION

[0001] The present invention relates to print quality optimization, and more particularly to a method for print quality adjustment for grouped regions of interest.BACKGROUND

[0002] Generally speaking, multiple elements can be printed on the same label. For example, barcode symbologies (e.g., QR code, code 128, or code 39) can be combined with fonts or designs (e.g., black bar, or logo). Most printers allow selecting only unified print quality settings, which pertain to the collection of the elements to be printed in general, and do not take into account print quality requirements preferred for those elements individually. Consequently, the selected settings may not be optimal for every barcode symbology, font, and design on the label. This often leads to print quality variation between the elements displayed on the same label. Moreover, variation in thermal printhead pressure and heater element resistance may further lead to print quality variation throughout different areas of the same printed label.

[0003] Several attempts have been made to address this issue. For example, U.S. Pat. No. 8,774,654 by Kielland discloses a thermal printhead with four sets of heating elements arranged in rows, and controlled individually by driving circuits, while strobe signals are provided to each set in a particular pattern. However, the reference does not disclose print quality variation on desired regions within the same label. U.S. Pat. No. 5,809,214 by Nureki et al. discloses a thermal printer having a printhead divided into rows of heating blocks, which are driven by individual driver units. However, the reference does not disclose controlling heating arrays individually to optimize print quality of particular regions of a label. U.S. Pat. No. 5,085,529 by McGourty et al. discloses a method of printing on a print sheet having a score line across it. However, the reference does not disclose variation in print quality between different print areas. Additionally, the reference does not disclose a thermal printhead having multiple heating elements. U.S. Pat. No. 7,941,750 by Laughlin discloses an inkjet printer capable of adjusting print quality for different regions. However, the reference is not related to a thermal printer, and does not disclose individual control of multiple heating elements on a printhead for controlling print quality at a desired region of a print media. Consequently, none of the references mention printing different information of different print quality on desired regions of interest at a print media with a thermal printer. JPS60168669A discloses a method in which ratios of printing data are calculated for every block and printing energy is calculated, and on the results of the calculation, electrification of unit heating elements is controlled for every block.

[0004] Therefore, a need exists for a method of adjusting print quality settings, which can account for individual requirements of each element to be presented on print media.SUMMARY

[0005] The present invention is defined by the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 schematically depicts an exemplary embodiment of a thermal printhead circuit diagram according to the present invention. Figure 2A graphically depicts an image to be printed on print media divided into regions of interest, not according to the present invention. Figure 2B graphically depicts an image to be printed on print media divided into regions of interest, according to the present invention. Figure 2C graphically depicts an image to be printed on print media divided into regions of interest, according the present invention. Figure 3 schematically depicts a method for print settings control, not according to the present invention. Figure 4 schematically depicts a method for printing, not according to the present invention. Figure 5 schematically depicts a method for print quality adjustment, according to the present invention. DETAILED DESCRIPTION

[0007] The present invention embraces methods for print quality adjustment for individual regions of interest.

[0008] Print quality settings of a printer are usually determined by balancing requirements for different barcode symbologies and designs to be printed on the same print media (e.g., a label), which can result in a print quality variation. To overcome this issue, a print area can be segmented into rows and / or columns of regions of interest, followed by applying separate print settings optimal for each element in each region of interest. Different print quality settings applied to individual regions can also be used to compensate for darkness variation in different areas of the print media. For example, the darkness variation can occur between a left and right sides of the printed label due to resistance and pressure variation.

[0009] Figure 1 schematically depicts an exemplary embodiment of a thermal printhead circuit diagram. Firings of thermal printhead heater elements can be controlled by strobe lines (labeled STB1 - STB6 in the diagram). Each strobe line can control firing durations of a group of heater elements (e.g., STB1 can control dots 1-256, etc.). By using different strobe signals for each of the strobe lines, energy of each heater element group can be adjusted by changing a corresponding strobe duration.

[0010] Figure 2A graphically depicts an image 002 to be printed on print media divided into regions of interest. As shown in Fig. 2A , the first column of a region of interest (ROI) is marked with a first print line 004 and a next user defined print line 006. The last column of the ROI is marked with a last user defined print line 008 and a last print line of the print job 010. User can define any print line (for example, line 012) as a vertical segmentation line of the ROIs. Each individual ROI can be identified by its row and / or column number. For example, ROI(1,4) 014 shown in Fig. 2A , refers to a ROI defined by the first row and the fourth column. Distance between rows 016 can be fixed, and determined by a heater element group. Printing direction can be chosen to be from the right-hand side of the figure to the left-hand side of the figure.

[0011] Figures 2B and 2C graphically depict an image 002 to be printed on print media divided into regions of interest, according to embodiments. Fig. 2B shows how different groups of ROIs can be grouped together, and have print quality settings assigned to the groups to optimize print quality for different symbologies and designs. Specifically, Group A, marked with reference number 020, includes ROI(1,1), ROI(2,1), ROI(3,1), and ROI(4,1); Group B includes ROI(1,2), ROI(2,2), and ROI(3, 2); Group C, marked with reference number 022, includes ROI(1,3), ROI(2,3), and ROI(3,3); and Group D, marked with reference number 024, includes ROI(4,3).

[0012] Figure 2C shows how different groups of ROIs can be grouped together, and have print quality settings assigned to the groups to compensate for print quality variation from a left to a right side of the label. Specifically, Group A, marked with reference number 030, includes ROI(1,1); Group B, marked with reference number 032, includes ROI(2,1); Group C, marked with reference number 034, includes ROI(3,1); and Group D, marked with reference number 036, includes ROI(4,1).

[0013] Figure 3 shows a method 100 for print settings control. At 102, an image to be printed on print media is divided into a plurality of regions of interest. At 104, the plurality of regions of interest is analyzed to determine one or more printing requirements for each region of interest. At 106, the determined printing requirements are used to calculate individual strobe durations. At 108, the calculated strobe durations are used to adjust individual strobe signals. At 110, the strobe signals are transmitted to a thermal printhead.

[0014] Transmitting the strobe signals, 110, can include transmitting all the strobe signals simultaneously. Additionally, transmitting the strobe signals simultaneously can include transmitting the signals with a field-programmable gate array (FPGA). Adjusting individual strobe signals, 108, can include adjusting energy of one or more heater elements of the thermal printhead.

[0015] Figure 4 shows a method 200 for printing. At 202, one or more print quality requirements are analyzed for a printing area. At 204, one or more settings for one or more heater elements of one or more strobe lines are adjusted based on the requirements analysis. At 206, a plurality of individual strobe signals is provided to the strobe lines.

[0016] Adjusting settings for heater elements, 204, can include adjusting energy and / or firing durations. Providing a plurality of individual strobe signals, 206, can include providing a plurality of individual strobe signals with an FPGA-based driver circuit. Analyzing print quality requirements for a printing area, 202, can include separating the printing area into one or more areas of interest. Additionally, separating a printing area into areas of interest can include separating the printing area into rows and / or columns. The method 200 can further include determining individual print quality requirements for the one or more areas of interest. For example, print quality requirements can include temperature of a thermal printhead, tension on a platen roller, and / or printing speed. Additionally, analyzing print quality requirements, 202, can include analyzing a print job request.

[0017] Figure 5 shows a method 300 for print quality adjustment, according to an embodiment. At 302, a print area is segmented into region-of-interest sections. At 304, one or more print quality settings are selected for each region-of-interest section. At 306, the selected print quality settings are used to adjust one or more printing parameters of one or more thermal printhead heater elements for each corresponding region-of-interest section.

[0018] In an embodiment, segmenting a print area into region-of-interest sections, 302, can include segmenting the print area in rows. Additionally, the method 300 can include segmenting the print area in columns. Adjusting printing parameters, 306, can include adjusting strobe durations for one or more heater groups. Selecting print quality settings, 304, can include selecting darkness, contrast, and / or media sensitivity. Segmenting a print area, 302, can include segmenting a print area having one or more barcodes and / or one or more designs.

[0019] Device and method components are meant to show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the invention with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. In various embodiments, the sequence in which the elements of appear in exemplary embodiments disclosed herein may vary. Two or more method steps may be performed simultaneously or in a different order than the sequence in which the elements appear in the exemplary embodiments.

[0020] In the specification and / or figures, typical embodiments of the invention have been disclosed. The present invention is not limited to such exemplary embodiments. The use of the term "and / or" includes any and all combinations of one or more of the associated listed items. The figures are schematic representations and so are not necessarily drawn to scale. Unless otherwise noted, specific terms have been used in a generic and descriptive sense and not for purposes of limitation.

Claims

1. A method of printing a print area (002) having one or more bar codes on a label using a thermal printhead having heater elements arranged in groups and strobe lines for adjusting the energy of a group of heater elements, the method comprising: segmenting (302) the print area (002) into a plurality of region-of-interest, ROI, sections; grouping the plurality of ROI sections into a plurality of groups of ROI sections (020-024, 030-036); selecting (304) print quality settings for the plurality of groups of ROI sections (020-024, 030-036); analyzing one or more print quality requirements of the plurality of groups of ROI sections (020-024, 030-036); adjusting (306) printing parameters of the heater elements arranged in the groups based on the selected print quality settings and the requirements analysis of the plurality of groups of ROI sections (020-024, 030-036); and providing a plurality of individual strobe signals to the strobe lines to adjust the printing parameters for the heater elements arranged in the groups.

2. The method according to claim 1, wherein adjusting (306) the printing parameters of the heater elements arranged in the groups comprises adjusting energy and / or firing durations of the heater elements.

3. The method according to claim 1, wherein providing the plurality of individual strobe signals comprises providing the plurality of individual strobe signals with a field-programmable gate array, FPGA, -based driver circuit.

4. The method according to claim 1, wherein segmenting (302) the print area (002) into the plurality of ROI sections comprises segmenting the print area (002) into rows and / or columns.

5. The method according to claim 1, wherein analyzing the one or more print quality requirements comprises analyzing a print job request.

6. The method according to claim 1, wherein selecting (304) the print quality settings comprises selecting at least one of darkness, contrast, and media sensitivity.

7. The method according to claim 1, wherein the one or more print quality requirements comprise at least one of a temperature of the thermal printhead, tension on a platen roller, and a printing speed.