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EP-4741167-A1 - METHOD OF OPERATING A THERMAL PRINTER

EP4741167A1EP 4741167 A1EP4741167 A1EP 4741167A1EP-4741167-A1

Abstract

The invention relates to a method for operating a thermal printer (2), at least comprising the step: (S300) Preheating a printhead (4) of the thermal printer (2) by controlling the printhead (4) with a preheating control signal (VAS), wherein at least one preheating value of the preheating control signal (VAS) has a shorter signal duration and/or a lower signal amplitude than a print value of a print control signal (DAS) for generating a print on a printed product (8).

Inventors

  • BALDIG, Klaus

Assignees

  • GeBE Elektronik und Feinwerktechnik GmbH

Dates

Publication Date
20260513
Application Date
20241107

Claims (14)

  1. Method for operating a thermal printer (2), at least including the step: (S300) Preheating a printhead (4) of the thermal printer (2) by controlling the printhead (4) with a preheating control signal (VAS), wherein at least one preheat value of the preheat control signal (VAS) has a shorter signal duration and/or a lower signal height than a pressure value of a pressure control signal (DAS) for generating an imprint on a printed product (8).
  2. Method according to claim 1, wherein the preheat value of the preheat control signal (VAS) is a first time period (T1) and the pressure value of the pressure control signal (DAS) is a second time period (T2).
  3. Method according to claim 2, wherein the first time period (T1) is 1/10 to 1/1000, in particular 1/100 to 1/300, in particular 1/30 to 1/50, of the second time period (T2).
  4. Method according to any one of claims 1 to 3, wherein the printed product (8) is a linerless printed product.
  5. Method according to any one of claims 1 to 4, comprising the further steps: (S100) Reading a temperature value (W) indicative of a temperature, and (S200) Comparing the temperature value (W) with at least one lower reference value (UR) and performing step (S300) Preheating the printhead (4) of the thermal printer (2) if the temperature value (W) is less than the lower reference value (UR).
  6. Method according to one of claims 1 to 5, wherein in step (S300) preheating a printhead (4) of the thermal printer (2) a signal sequence (SF) is used, wherein the signal sequence (SF) contains at least the preheating control signal (VAS), wherein the signal sequence (SF) is at least a binary signal sequence with at least one logic one level and one logic zero level.
  7. Computer program product configured to execute a method according to any one of claims 1 to 6.
  8. Thermal printer (2) with at least one printhead (4), wherein the printhead (4) can be controlled with a preheating control signal (VAS) and with a print control signal (DAS), wherein at least one preheating value of the preheating control signal (VAS) has a shorter signal duration and/or a lower signal height than a print value of the print control signal (DAS) for generating an imprint on a printed product (8).
  9. Thermal printer (2) according to claim 8, wherein the preheat value of the preheat control signal (VAS) is a first time period (T1) and the pressure value of the pressure control signal (DAS) is a second time period (T2).
  10. Thermal printer (2) according to claim 9, wherein the first time period (T1) is 1/10 to 1/1000, in particular 1/100 to 1/300, in particular 1/30 to 1/50, of the second time period (T2).
  11. Thermal printer (2) according to one of claims 8 to 10, wherein the printed product (8) is a linerless printed product.
  12. Thermal printer (2) according to one of claims 8 to 11, with a control unit (10), wherein the control unit (10) is configured to read a temperature value (W) indicative of a temperature, which to compare the temperature value (W) with at least one lower reference value (UR) and to perform preheating of the printhead (4) of the thermal printer (2) when the temperature value (W) is less than the lower reference value (UR).
  13. Thermal printer (2) according to one of claims 8 to 12, with a control unit (10), wherein the control unit (10) is configured to provide a signal sequence (SF), wherein the signal sequence (SF) contains at least the preheating control signal (VAS), wherein the signal sequence (SF) is at least a binary signal sequence with at least one logic one level and one logic zero level.
  14. Control unit (10) for a thermal printer (2) according to one of claims 8 to 13.

Description

The invention relates to a method for operating a thermal printer. Furthermore, the invention relates to a computer program, a thermal printer, and a control unit for such a thermal printer. A printer is a device designed to read text and/or graphics in machine-readable form and transfer them to a substrate to produce a printed product. A substrate is understood to be a printing material that can be printed using a printing process carried out by the printer, while the final result is referred to as a printed product. Thermal printing is a printing process that relies on the application of heat to a specific point on the substrate. Common applications include cash register printers, ticket printers, and parking ticket printers. In this case, the printer is designed as a label printer, capable of continuously printing labels from rolls or fanfolds. For example, such a thermal printer can be designed as a ticket printer. However, various performance parameters, such as the print speed of such a thermal printer, are temperature-dependent. The warmer the printhead of the thermal printer is, the less energy is required for printing and the faster the printing process can be carried out. Low ambient temperatures reduce the print speed because longer heating is required to generate the necessary activation energy or to reach a color change temperature at which the thermal paper changes color due to the heat. Therefore, there is a need to show ways in which the operation of such a thermal printer can be improved even at low temperatures. The object of the invention is solved by a method for operating a thermal printer, at least with the step of: Preheating a printhead of a thermal printer by controlling the printhead with a preheating control signal, wherein at least one preheating value of the preheating control signal has a shorter signal duration and/or a lower signal amplitude than a print value of a print control signal for generating an imprint on a printed product. To preheat the printhead, heating elements within the printhead are controlled with signals that have a shorter duration and/or lower amplitude than the values used to bring the heating elements up to their target printing temperature. At temperatures below the target printing temperature, no printing occurs because the color change temperature, at which the thermal paper undergoes a color change due to heat, is not reached. This allows the printhead to be preheated before the actual printing process without additional heating elements. This improves operation at low temperatures, such as printhead temperatures in the range of 10°C to 60°C, for example, below 32°C, as it increases printing speed. According to one embodiment, the preheating value of the preheating control signal represents a first time duration, and the pressure value of the pressure control signal represents a second time duration. Thus, the preheating value of the preheating control signal differs from the pressure value of the pressure control signal by a shorter signal duration, while both values have the same signal amplitude. This allows the pressure value of the pressure control signal and the preheating value of the preheating control signal to be provided particularly easily by varying the duty cycle. However, it is also possible, as an alternative or in addition to the signal duration, to select a signal amplitude of the preheating value of the preheating control signal that is smaller than the pressure value of the pressure control signal. According to another embodiment, the first duration is 1/10 to 1/1000, in particular 1/100 to 1/300, and especially 1/30 to 1/50, of the second duration. For example, the first duration can be in the range of several hundred µs, while the second duration is in the range of a few µs. This ensures that there is no unintentional printing on the substrate during preheating. According to another embodiment, the printed product is a linerless printed product. The linerless printed product is created by printing on a linerless substrate. A linerless substrate is understood to be a carrier-free, continuous substrate wound onto a roll, which can be printed on one side using a thermal printing process. Such a linerless substrate has an adhesive coating on its reverse side, while a release layer is provided on its front side. When wound onto a roll, this release layer comes into contact with the adhesive coating on the reverse side, preventing unwanted sticking of the wound-up linerless substrate. With linerless substrates, the tendency for streaking is further increased when the thermal printer's printhead is cold, as silicone from the linerless substrate partially detaches and accumulates on the printhead. This silicone buildup can prevent printing in areas where silicone has accumulated. The result is the formation of unwanted streaks in the printing direction. Preheating can counteract streaking on the printed product, which would otherwise