JP4398481B2 - Thermal transfer printing apparatus and printing method - Google Patents

Description

  The present invention relates to a thermal transfer printing apparatus and a printing method, and more particularly to a thermal transfer printing apparatus and a printing method for compensating output energy of a thermal transfer head by adjusting an energy / image gradation comparison table.

  The color depth of the thermal sublimation printer varies depending on the energy (product of power and printing time) of the thermal transfer head (TPH). In other words, if the printing time is constant, the power of the thermal transfer head must be constant in order to control the color density of the thermal sublimation printer.

  The power of the thermal transfer head varies depending on the resistance value of the thermal transfer head and the drive voltage input from the outside. However, since the resistance value of the thermal transfer head generally has an error of ± 10%, in order to make the power constant, it is necessary to optimally adjust the drive voltage according to the resistance value of each thermal transfer head. .

  Therefore, the conventional technology provides a DC power converter and a voltage dividing circuit between the thermal transfer head and the power supply of the thermal sublimation printer, and adjusts the resistance value of the voltage dividing circuit to optimize the driving voltage of the thermal transfer head. Keep the power of the thermal transfer head constant.

  In the above conventional technique, a mechanical variable resistor is provided in the voltage feedback loop of the DC power supply converter, thereby adjusting the driving voltage of the thermal transfer head. Please refer to FIG. FIG. 1 is an explanatory view showing a conventional thermal transfer printing apparatus 100. As shown in FIG. 1, the thermal transfer printing apparatus 100 includes a thermal transfer head 102, a voltage dividing circuit 104, a DC power source 106, and a DC / DC regulator 108, of which the voltage dividing circuit 104 is the first one. It includes one resistor R1, a second resistor R2, and a mechanical variable resistor VR1.

  However, since the resistance value of the mechanical variable resistor has to be adjusted manually, there are disadvantages such that errors are likely to occur, production efficiency is reduced, and labor costs are increased. Further, the resistance value of the mechanical variable resistor is disturbed due to aging or vibration, and the driving voltage of the thermal transfer head is unstable, so that there is a possibility that the color is not dark and the image quality is deteriorated. In addition, the use of an expensive power converter and power loss during conversion are also problems of the above technique.

Apart from the above technique, U.S. Pat. No. 4,573,058 discloses a technique for controlling the driving voltage of the thermal transfer head using a voltage regulator (VR) and a constant current diode. However, this technique is expensive and uses a constant current diode with a large error, so that the effect is limited. In addition, the technology shown in US Pat. No. 5,745,146 has a low output resistance for the required analog / digital converter (ADC), so an amplifier with a high output resistance must be added to measure the voltage division value of the voltage divider circuit. In other words, the high-cost problem cannot be solved. This patent is suitable only for barcode printers and not for color printing.
US Pat. No. 4,573,058 Specification US Pat. No. 5,745,146 specification

  In order to solve the above-described problems, an object of the present invention is to provide a thermal transfer printing apparatus and a printing method that compensate for output energy of a thermal transfer head by adjusting an energy / image gradation comparison table.

  The present invention provides a printing method for a thermal transfer printing apparatus. The method stores at least one predetermined control comparison table that records control parameter settings of the thermal transfer head corresponding to individual image gradations under a predetermined power value, calculates an actual power value of the thermal transfer head, and The objective control contrast table is defined based on the actual power value, the predetermined power value, and the predetermined control contrast table, and the thermal transfer head is driven based on the objective control contrast table for printing.

  The present invention further provides a thermal transfer printing apparatus. The printing apparatus includes a storage unit for storing at least one predetermined control comparison table for recording control parameter settings of the thermal transfer head corresponding to each image gradation under a predetermined power value, and an actual power value of the thermal transfer head. A control unit for calculating and defining a target control control table based on the actual power value, the predetermined power value, and the predetermined control control table, and further driving and printing the thermal transfer head based on the target control control table;

  The present invention can make the print output energy of the thermal transfer head constant even when the actual power value of the thermal transfer head is not constant. Further, since the present invention does not need to adjust the driving voltage in accordance with the resistance value of the thermal transfer head, the mechanical variable resistor and the power converter are not required, and the conventional mechanical variable resistor and the power converter originated from the mechanical variable resistor and the power converter. Can solve the problem.

  In order to describe the characteristics of such an apparatus in detail, a specific example will be given and described below with reference to the drawings.

  As is well known to those skilled in the art, it is possible for electronic product manufacturers to refer to the same element in terms different from those described in this specification and the claims. Therefore, the present invention specifies an element exclusively by function, not a name given to the element. It should be understood that terms such as “including” and “having” used in the present specification and claims should not be construed restrictively, and are not limited to those exemplified. “Coupled” means direct electrical connection or indirect electrical connection. Thus, “the first device is coupled to the second device” means that both devices are directly connected to each other or to each other via other devices or connections.

  Please refer to FIG. FIG. 2 is an explanatory view showing a thermal transfer printing apparatus 200 according to the present invention. As shown in FIG. 2, the thermal transfer printing apparatus 200 includes a thermal transfer head 202, a voltage dividing circuit 204, an analog / digital converter (ADC) 206, a storage unit 208, a control unit 210, a switch 212, a DC power source. 214, of which the voltage dividing circuit 204 includes a first resistor R11 and a second resistor R21. It should be noted that the number of resistors included in the voltage dividing circuit 204 is not limited to two.

  The resistance value of the thermal transfer head 202 generally has a Gaussian distribution within a specific range (for example, a reference resistance value ± 10%). Therefore, as shown in FIG. 3, the power value of the thermal transfer head 202 also has a Gaussian distribution within a specific range (for example, ± 10% of the power value P). The present invention creates at least one candidate energy / image gradation comparison table (for example, candidate energy / image gradation comparison tables T1 and T2 shown in FIG. 4) based on the power value distribution of the thermal transfer head, and stores the storage unit 208. Save to. For example, the candidate energy / image gradation contrast table T1 shown in FIG. 4 corresponds to the reference power value P1, and the candidate energy / image gradation contrast table T2 corresponds to the reference power value P2. The storage unit 208 further stores the firmware FW and the resistance value R of the thermal transfer head 202. Wi shown in FIG. 4 is an energy control value corresponding to the image gradation Di. The energy control value controls the heating time and the number of times of heating of the thermal transfer head, and has a one-to-one correspondence with the heating energy. For example, if the image gradation is 8 bits (i = 1, 2, 3 to 256) and the energy control value is 16 bits, the 8-bit image gradation is 16 bits according to the energy / image gradation comparison table. The ink ribbon can be heated by a predetermined heating means based on the energy control value. It should be noted that the number of the energy / image gradation comparison table is not limited to two.

  Subsequently, the control unit 210 executes the firmware FW, and calculates the actual voltage value of the thermal transfer head 202 based on the divided voltage value of the voltage dividing circuit 204. The voltage dividing circuit 204 generates a detection voltage based on the drive voltage of the thermal transfer head 202, and the ADC 206 generates a detection voltage value by analog / digital conversion of the detection voltage, and based on this, the actual voltage value of the thermal transfer head 202 is generated. Determine. Thereafter, the firmware FW is executed by the control unit 210, the resistance value R of the thermal transfer head 202 is read from the storage unit 208, and the actual voltage value of the thermal transfer head 202 and the actual resistance value R of the thermal transfer head 202 are based on the resistance value R of the thermal transfer head 202. The power value Pa is calculated.

  Thereafter, the firmware FW is executed by the control unit 210, and one of the candidate energy / image gradation comparison tables T1 and T2 is stored in the predetermined energy / image gradation from the storage unit 208 based on the actual power value Pa of the thermal transfer head 208. Selected as a target table. For example, if the actual power value Pa of the thermal transfer head 202 is close to the reference power value P1 (see FIG. 5), the control unit 210 sets the candidate energy / image gradation comparison table T1 corresponding to the reference power value P1 to a predetermined energy / image level. The control table is selected, and the firmware FW is further executed to calculate the energy compensation coefficient A from the reference power value P1 corresponding to the predetermined energy / image gradation comparison table T1 and the actual power value Pa of the thermal transfer head (A = P1). / Pa). Here, since Pa is larger than P1, the energy compensation coefficient A is smaller than 1. Thereafter, the control unit 210 executes the firmware FW, adjusts the predetermined energy / image gradation comparison table T1 based on the energy compensation coefficient A, and generates the target energy / image gradation comparison table Tt. According to the target energy / image gradation comparison table Tt, since the energy control value Wi ′ = A * Wi, the energy control value Wi ′ at the same gradation is smaller than Wi (see FIG. 6). Thereafter, the firmware FW is executed by the control unit 210, and printing is performed by driving the thermal transfer head 202 (its actual power value Pa is higher than the reference power value P1) based on the target energy / image gradation comparison table Tt. In the present invention, the control unit 210 executes the firmware FW and switches the control switch 212 to control the print output energy of the thermal transfer head 202. When the actual power value Pa of the thermal transfer head is larger than the reference power value P1, the reference energy value corresponding to the reference power value P1 is used by the thermal transfer head 202 using the energy / image gradation comparison table adjusted as described above. Is generated. Even when the actual power value Pa is close to the reference power value P1 and smaller than the reference power value P1, the energy / image gradation comparison table is finely adjusted by the same method as described above, and the reference power value P1 is detected by the thermal transfer head 202. A reference energy value corresponding to can be generated.

  On the other hand, when the actual power value Pa of the thermal transfer head 202 is close to the standard power value P2 (see FIG. 7), the control unit 210 displays the energy / image gradation comparison table T2 corresponding to the reference power value P2 with a predetermined energy / image level. The control table is selected, and the firmware FW is further executed to calculate the energy compensation coefficient A based on the reference power value P2 corresponding to the predetermined energy / image gradation comparison table T2 and the actual power value Pa of the thermal transfer head (A = P2 / Pa). Here, since Pa is smaller than P2, the energy compensation coefficient A is larger than 1. Thereafter, the control unit 210 executes the firmware FW, adjusts the predetermined energy / image gradation comparison table T2 based on the energy compensation coefficient A, and generates the target energy / image gradation comparison table Tt. According to the target energy / image gradation comparison table Tt, since the energy control value Wi ′ = A * Wi, the energy control value Wi ′ at the same gradation is larger than Wi (see FIG. 8). Thereafter, the firmware FW is executed by the control unit 210, and printing is performed by driving the thermal transfer head 202 based on the target energy / image gradation comparison table Tt. According to the present invention, the firmware FW is executed by the control unit 210 and the control switch 212 is switched to control the output energy of the thermal transfer head 202 during printing. When the actual power value Pa of the thermal transfer head is smaller than the reference power value P2, the reference energy value corresponding to the reference power value P2 is used by the thermal transfer head 202 using the energy / image gradation comparison table adjusted as described above. Can be generated. Even when the actual power value Pa is close to the reference power value P2 and larger than the reference power value P2, the energy / image gradation comparison table is finely adjusted in the same manner as described above, and the standard power value P2 is detected by the thermal transfer head 202. A standard energy value corresponding to can be generated.

Please refer to FIG. FIG. 9 is a flowchart of a method for controlling the output energy of the thermal transfer head according to the present invention. The following method is executed by the thermal transfer printing apparatus 200 shown in FIG.

Step 900: Start.
Step 902: Based on the distribution range of the power value of the thermal transfer head 202, at least one candidate energy / image gradation comparison table, firmware, and resistance value of the thermal transfer head 202 are stored in the storage unit 208.
Step 904: The firmware is executed by the control unit 210, and the actual voltage value of the thermal transfer head 202 is calculated based on the divided voltage value of the voltage dividing circuit 204.
Step 906: The control unit 210 executes the firmware, reads the resistance value of the thermal transfer head 202 from the storage unit 208, and calculates the actual power value of the thermal transfer head 202 based on the actual voltage value of the thermal transfer head 202.
Step 908: The control unit 210 executes the firmware, and selects one of the candidate energy / image gradation comparison tables from the storage unit 208 as a predetermined energy / image gradation comparison table based on the actual power value of the thermal transfer head 202. .
Step 910: The firmware is executed by the control unit 210, and an energy compensation coefficient is calculated based on the reference power value of the predetermined energy / image gradation comparison table and the actual power value of the thermal transfer head.
Step 912: The firmware is executed in the control unit 210, the predetermined energy / image gradation comparison table is adjusted based on the energy guarantee coefficient, and the target energy / image gradation comparison table is defined.
Step 914: The firmware is executed by the control unit 210, and the thermal transfer head 202 is driven and printed with the target energy / image gradation comparison table.
Step 916: End.

The above is a preferred embodiment of the present invention and does not limit the scope of the present invention. Therefore, any modifications or changes that can be made by those skilled in the art, which are made within the spirit of the present invention and have an equivalent effect on the present invention, shall belong to the scope of the claims of the present invention. To do.

  The present invention compensates for the output energy of the thermal transfer head by adjusting the energy / image tone contrast table. Such a technique can be implemented.

It is explanatory drawing showing the conventional thermal transfer printing apparatus. It is explanatory drawing showing the thermal transfer printing apparatus by this invention. It is explanatory drawing showing the electric power value distribution of the thermal transfer head by this invention. It is explanatory drawing showing the candidate energy / image gradation contrast table by this invention. It is explanatory drawing showing the electric power value distribution and actual electric power value of the thermal transfer head by this invention. It is explanatory drawing showing the method of adjusting predetermined energy / image gradation with the energy compensation coefficient by this invention. It is explanatory drawing showing the electric power value distribution of the thermal transfer head by this invention, and another actual electric power value. It is explanatory drawing showing the method of adjusting predetermined energy / image gradation with the other energy compensation coefficient by this invention. 3 is a flowchart of a method for controlling output energy of a thermal transfer head according to the present invention.

Explanation of symbols

100, 200 Thermal transfer printing apparatus 102, 202 Thermal transfer head 104, 204 Voltage dividing circuit 106, 214 DC power supply 108 DC / DC regulator 206 ADC
208 storage unit 210 control unit 212 switch R1, R11 first resistor R2, R21 second resistor VR1 mechanical variable resistor

Claims (7)

A thermal transfer printing apparatus printing method,
And storing at least one candidate energy / image gradation control tables that record energy control value of the thermal transfer head corresponding to each image tone under the plurality of reference power value,
Calculating the actual power value of the thermal head,
Selecting one of the at least one candidate energy / image gradation contrast table as a predetermined energy / image gradation contrast table based on the actual power value;
The actual power value, and the reference power value, the steps of the the predetermined energy / image gradation reference table, based on, to produce the desired energy / image gradation reference table,
And printing by driving the thermal head on the basis of the target energy / image gradation reference table,
Including
The target energy / image gradation contrast table defines an energy compensation coefficient based on a ratio between the reference power value and the actual power value, and adjusts the predetermined energy / image gradation contrast table based on the energy compensation coefficient. Generated by the
A printing method characterized by the above. It said printing method further includes the step of storing the resistance value of the thermal head,
Calculating the actual power value of the thermal head,
Calculating an actual voltage value of the thermal head,
A step wherein said resistance value of the thermal transfer head based actual voltage value, the, calculating the actual power value of the thermal head,
including,
The printing method according to claim 1, wherein: Calculating the actual voltage of the thermal head,
Generating a sensing voltage based on the actual driving voltage of the thermal head,
And generating the detection voltage as the detection voltage value by the analog / digital converter,
A step of determining the actual voltage value based on the detection voltage value,
including,
The printing method according to claim 2 . Selecting one of the at least one candidate energy / image gradation contrast table as a predetermined energy / image gradation contrast table ,
A step of selecting the nearest candidate power value to the actual power value from a plurality of candidate power value,
A step of selecting said candidate energy / image gradation control table corresponding to the candidate power value as the predetermined energy / image gradation reference table,
including,
The method of claim 1 wherein: A thermal transfer printing device,
A storage unit for storing at least one candidate energy / image gradation control tables that record energy control value of the thermal transfer head corresponding to each image tone under the plurality of reference power value,
A control unit connected to the storage unit, wherein an actual power value of the thermal transfer head is calculated, and one of the at least one candidate energy / image gradation comparison table is determined based on the actual power value as a predetermined energy / An image gradation control table is selected and a target energy / image gradation comparison table is generated based on the actual power value, the reference power value, and the predetermined energy / image gradation contrast table, and the target energy / image gradation contrast table is generated. A control unit for driving and printing the thermal transfer head based on a table;
Including
The objective control comparison table is generated by determining an energy compensation coefficient based on a ratio between the reference power value and the actual power value, and adjusting the predetermined energy / image gradation comparison table based on the energy compensation coefficient. The
A printing apparatus characterized by that. The storage unit further stores firmware,
The control unit calculates the actual power value of the thermal transfer head by executing the firmware, selects the predetermined energy / image gradation contrast table, generates the target energy / image gradation contrast table, and Printing by driving the thermal transfer head;
The printing apparatus according to claim 5 .   The storage unit further stores a resistance value of the thermal transfer head,
  The firmware calculates the actual power value of the thermal transfer head based on the resistance value of the thermal transfer head and the actual voltage value of the thermal transfer head.
  The printing apparatus according to claim 6.

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