JP6762211B2 - Thermal transfer printer and printing system - Google Patents

Description

The present invention relates to a thermal transfer printer and a printing system using a thermal transfer printer.

It relates a thermal transfer printer, stores the lifetime print number for each heating elements of the thermal head (for example, 10 ⁶ times), when the print number of the most output frequency heating element has reached the lifetime print number of the thermal head life A technique for outputting a warning signal indicating that the temperature has been reached has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 8-142637 (see paragraphs 0018 to 0020)

The thermal transfer printer transfers ink to paper by superimposing the ink sheet and paper and transporting the ink while heating with a thermal head. The ink sheet is formed by forming an ink layer (dye layer) and an overcoat layer on the surface of a base film. Further, in recent years, in order to cope with the increase in the transfer speed due to the shortening of the printing time and the increase in the heat generation amount of the thermal head due to the increase in the density of the image, the back surface of the base film of the ink sheet has slipperiness and slipperiness. A heat-resistant slippery layer having excellent heat resistance is provided.

However, the constituent material of the heat-resistant slipping layer of the ink sheet may peel off and fall off, forming a residue called ink residue and adhering to the thermal head. When the amount of ink residue adhering to the thermal head increases, heating of the ink sheet is hindered, and as a result, streaky printing defects occur in the paper transport direction, and the paper may be scratched.

As described above, a technique for notifying the user of the life of the heat generating element of the thermal head has been developed, but a technique for suppressing printing defects caused by ink residue has not yet been developed.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to suppress printing defects due to ink residue adhering to the thermal head and to improve print quality.

The thermal transfer printer of the present invention has a transport unit for transporting paper, a platen roller for crimping an ink sheet and paper, and a plurality of heat generating elements arranged in one direction, and is arranged facing the platen roller to form an ink sheet. To the thermal head that heats and transfers the ink of the ink sheet to the paper, the history storage unit that stores the history information of the heat generation time for each heat generating element of the thermal head, and the history information and image data stored in the history storage unit. Based on this, it includes a prediction unit that obtains a predicted accumulation amount of ink residue for each heat generating element of the thermal head, and a print control unit that performs print control based on the predicted accumulation amount obtained by the prediction unit.

The printing system of the present invention includes a plurality of thermal transfer printers and an information processing device. Each of the plurality of thermal transfer printers has a transport unit for transporting the paper, a platen roller for crimping the ink sheet and the paper, and a plurality of heat generating elements arranged in one direction, and is arranged to face the platen roller. It includes a thermal head that heats the ink sheet and transfers the ink of the ink sheet to paper, and a history storage unit that stores history information of the heat generation time for each heat generating element of the thermal head. The information processing device is calculated by a prediction unit and a prediction unit that obtain a predicted accumulation amount of ink residue for each heat generating element of the thermal head based on the history information and image data stored in the history storage unit for each of the plurality of thermal transfer printers. It is provided with a print control unit that selects one of a plurality of thermal transfer printers to execute printing based on the predicted accumulated amount.

According to the present invention, since printing control is performed based on the predicted accumulation amount of ink residue for each heat generating element of the thermal head, it is possible to suppress printing defects caused by ink residue and improve print image quality. In addition, since it is not necessary to frequently clean the thermal head and replace parts, the convenience for the user is improved.

It is a schematic diagram which shows the printing mechanism of the thermal transfer printer of Embodiment 1. It is a block diagram which shows the control system of the thermal transfer printer of Embodiment 1. FIG. It is a plan view (A) and a sectional view (B) of an ink sheet used in the thermal transfer printer of Embodiment 1, and a sectional view (C) of a paper. It is a flowchart which shows the printing process of the thermal transfer printer of Embodiment 1. It is a figure which shows the predicted accumulation amount (A) of ink residue and the example (B), (C) of switching of image data in the thermal transfer printer of Embodiment 1. FIG. It is a graph for demonstrating the calculation method of the predicted accumulation amount in the 1st modification of Embodiment 1. It is schematic diagram (A), (B) for demonstrating the method of switching the printing order of image data in the 2nd modification of Embodiment 1. FIG. 19 (A) and (B) are timing charts (A) and (B) for explaining a method of switching the printing speed in the third modification of the first embodiment. It is a block diagram which shows the print system of Embodiment 2. It is a flowchart which shows the printing process of the printing system of Embodiment 2. It is a figure which shows the predicted accumulation amount (A), (B) of ink residue in each thermal transfer printer of the printing system of Embodiment 2, and the example (C) of image data.

Embodiment 1.
<Structure of thermal transfer printer>
FIG. 1 is a schematic view showing a printing mechanism of the thermal transfer printer 1 of the first embodiment. The thermal transfer printer 1 is a so-called sublimation dye thermal transfer printer that transfers the sublimable dye ink applied to the ink sheet 9 to the paper 7 having a receiving layer.

As a printing mechanism, the thermal transfer printer 1 has a paper transport unit (conveyor unit) 8 that pulls out and conveys the paper 7 from the roll paper 6, a thermal head 10 having a heat generating element, and a platen roller 11 arranged to face the thermal head 10. The supply bobbin 14 for supplying the ink sheet 9, the supply bobbin drive unit 15 for rotating the supply bobbin 14, the take-up bobbin 16 for winding the ink sheet 9, and the take-up bobbin drive unit for rotating the take-up bobbin 16. 17 is provided, a paper ejection unit 13 for ejecting the paper 7, and a cutter (cutting portion) 12 for cutting the ejected paper 7.

The paper transport unit 8 transports the paper 7 drawn from the roll paper 6 to the thermal head 10. The supply bobbin 14 supplies the ink sheet 9 to the thermal head 10, and the take-up bobbin 16 winds the ink sheet 9 that has passed through the thermal head 10. The thermal head 10 has a plurality of heat generating elements (heat generating resistors) arranged in a row. The arrangement direction of the heat generating elements is the width direction of the ink sheet 9 (that is, the width direction of the paper 7). The platen roller 11 presses the paper 7 and the ink sheet 9 with the thermal head 10.

The thermal transfer printer 1 further includes an internal temperature sensor 19 for measuring the internal temperature of the thermal transfer printer 1, an internal humidity sensor 20 for measuring the internal humidity of the thermal transfer printer 1, and an ink sheet information sensor 21 for reading information on the ink sheet 9. To be equipped with. Further, inside the thermal head 10, a thermal head temperature sensor 10a (FIG. 2) for measuring the temperature of each heat generating element is provided.

FIG. 2 is a block diagram showing a control system of the thermal transfer printer 1. The thermal transfer printer 1 receives image data and information related to printing from an external information processing device 101 such as a personal computer, a communication unit 2, a storage unit 3 that stores image data, a control program, and the like, and the received image data. It has an image processing unit 4 that processes and converts it into print data, and a control unit 5 that controls the overall operation of the thermal transfer printer 1.

The storage unit 3 has a temporary storage memory such as a RAM that temporarily stores image data received by the communication unit 2, and a non-volatile memory that stores a control program, initial setting values, and the like. The non-volatile memory of the storage unit 3 is provided with a history storage unit 31 that stores history information of the heat generation time (energization time) of each heat generating element of the thermal head 10 and history information of the printing speed.

The control unit 5 is composed of, for example, a processor including a CPU or the like. The control unit 5 predicts the occurrence of printing defects due to ink residue for each heat generating element based on the calculation unit 51 that calculates the heat generation time for each heat generating element of the thermal head 10 and the history information stored in the history storage unit 31. It has a unit 52 and a print control unit 53 that performs print control based on the prediction result of the prediction unit 52.

The calculation unit 51, the prediction unit 52, and the print control unit 53 may be realized, for example, by the processor executing a program stored in the memory, or may be realized by a hardware circuit (processing circuit). Good.

Temperature information from the internal temperature sensor 19, humidity information from the internal humidity sensor 20, and ink sheet information from the ink sheet information sensor 21 are input to the control unit 5. Based on the input information, the control unit 5 sets the paper transport unit 8, the thermal head 10, the cutter 12, the paper discharge unit 13, the supply bobbin drive unit 15, and the take-up bobbin drive unit 17 of the printing mechanism shown in FIG. Drive control. The components of the thermal transfer printer 1 shown in FIG. 2 are connected to each other by a bus 18.

3A and 3B are a plan view and a cross-sectional view showing a configuration example of the ink sheet 9 used in the thermal transfer printer 1. FIG. 3C is a cross-sectional view showing a configuration example of the paper 7 used in the thermal transfer printer 1. As shown in FIG. 3A, the ink sheet 9 has a base film 9e, and on the surface thereof, Y (yellow) ink layers 9a and M (magenta) are formed along the longitudinal direction of the base film 9e. ) An ink layer 9b, a C (cyan) ink layer 9c, and an overcoat (OP) layer 9d are formed. As shown in FIG. 3B, a heat-resistant slippery layer 9f is formed on the back surface of the base film 9e.

The base film 9e is a film made of plastic and has a thickness of, for example, 3 to 12 μm. The Y ink layer 9a, the M ink layer 9b, and the C ink layer 9c are each formed of yellow, magenta, and cyan sublimating dyes, and have a thickness of, for example, 1 to 10 μm. The overcoat layer 9d is made of a material having weather resistance and abrasion resistance, and has a thickness of, for example, 1 to 10 μm. The heat-resistant slippery layer 9f is made of a material having excellent slipperiness and heat resistance, and has a thickness of, for example, 0.1 to 0.2 μm.

As shown in FIG. 3C, the paper 7 has a receiving layer 7b formed on the surface of the base material 7a. The receiving layer 7b receives the sublimation dye transferred from the ink sheet 9. The heat generating element of the thermal head 10 heats the ink layer of the ink sheet 9, and the ink is sublimated and transferred to the image receiving layer of the paper 7.

The basic printing operation by the thermal transfer printer 1 is as follows. When the communication unit 2 of the thermal transfer printer 1 receives image data and information related to printing (for example, paper size, print mode, image quality adjustment parameters, etc.) from the information processing device 101, the image processing unit 4 converts the image data into print data. Then, the control unit 5 controls the printing mechanism to print.

In the printing mechanism, the paper 7 is pulled out from the roll paper 6 by the paper transport unit 8 and transported to the thermal head 10. The paper 7 conveyed to the thermal head 10 is pressed against the ink sheet 9 supplied from the supply bobbin 14 between the thermal head 10 and the platen roller 11.

The paper transport unit 8 transports the paper 7 to the reference position in the direction indicated by the arrow A in FIG. 1, stops, and winds the ink sheet 9 in the opposite direction (at the same time, winds the ink sheet 9 with the winding bobbin 16) while the thermal head. The heat generation of each heat generating element of 10 is controlled, and the ink is transferred to the paper 7 for each line. By repeating this operation, the inks of the Y ink layer 9a, the M ink layer 9b, and the C ink layer 9c are transferred to the paper 7, and the overcoat of the overcoat layer 9d is further transferred to the paper 7. By forming an overcoat so as to cover the printed surface on the paper 7, the weather resistance and abrasion resistance of the printed matter are improved.

After transferring each ink and overcoat to the paper 7, the paper transport unit 8 transports the paper 7 in the direction indicated by the arrow A, and the cutter 12 transfers the paper 7 to a specified size (for example, 89 mm × in the case of L size). The paper is cut into 127 mm), and the paper ejection unit 13 ejects the paper 7 to the outside of the thermal transfer printer 1.

<About printing defects due to ink residue>
In recent years, the transport speed of the paper 7 and the ink sheet 9 has been increased in order to shorten the printing time, the amount of heat generated by the thermal head 10 has been increased in order to obtain a high-density image, and pressure bonding has been performed to improve the transferability of the ink. The pressure tends to be high. Along with this, the heat, frictional force and tension applied to the base film 9e tend to increase. Therefore, in order to prevent the base film 9e from melting and causing heat fusion, the heat-resistant slippery layer 9f having excellent heat resistance and slipperiness (wear resistance) is formed on the back surface of the base film 9e (FIG. 3 (B). )) Is provided.

However, since the heat resistance and abrasion resistance of the heat resistant slip layer 9f are not perfect, the heat resistant slip layer 9f of the ink sheet 9 is partially peeled off depending on the pressure, frictional force and heat received from the thermal head 10. It may fall off and adhere to the thermal head 10. This becomes a residue called ink residue.

When the accumulated amount (deposited amount) of ink residue adhering to the thermal head 10 increases, heat dissipation of the thermal head 10 is hindered and heat is less likely to be transferred to the ink sheet 9. Further, if the accumulated amount of ink residue is further increased, the heat generating element of the thermal head 10 may be damaged, resulting in shortening the life of the heat generating element.

In this way, the heat of the heat generating element of the thermal head 10 is less likely to be transferred to the ink sheet 9, or the heat generating element is damaged, which may cause a printing defect called "missing dots" in which white lines appear in the paper transport direction. is there. Further, the ink residue accumulated on the surface of the thermal head 10 may cause scratches (referred to as printing scratches) on the paper 7.

When missing dots or printing scratches are found in the thermal transfer printer, it is necessary to clean the ink residue adhering to the thermal head 10 or replace the thermal head 10. However, frequent cleaning or parts replacement imposes a heavy burden on the user of the thermal transfer printer (for example, a photo shop) in terms of working time and cost.

Therefore, the thermal transfer printer 1 of the first embodiment is configured to predict printing defects due to adhesion of ink residue and perform printing by a printing method that does not cause printing defects. This point will be described below.

<Method of predicting the occurrence of printing defects due to ink residue>
In the first embodiment, printing defects due to adhesion of ink residue are predicted as follows. The amount of ink residue generated is
(1) Heat generation time (energization time) of each heat generating element of the thermal head 10.
(2) It can be predicted based on two pieces of information, that is, the contact speed of the ink sheet with respect to each heat generating element of the thermal head 10.

First, the heat generation time Sn of the nth (n is a natural number) heat generating element of the thermal head 10 is the input image data I, the temperature Th of the thermal head 10 at the time of printing, the internal temperature Tk of the thermal transfer printer 1, and the internal humidity Hk. Therefore, it can be obtained by the following equation (1).
Sn = f (I, Th, Tk, Hk) ... Equation (1)

That is, in the equation (1), the heat generation time Sn of the nth heat generating element of the thermal head 10 is obtained by the function f having I, Th, Tk, and Hk as arguments.

The thermal transfer printer 1 generally has a plurality of printing modes having different printing speeds, such as a high printing speed in a high-speed mode that prioritizes printing speed and a slow printing speed in a high-quality mode that prioritizes image quality quality. Therefore, the contact speed of the ink sheet 9 with respect to the thermal head 10 can be obtained from the printing speed Ps corresponding to the designated printing mode. The heat generation time Sn is obtained for each heat generating element of the thermal head 10, while the printing speed Ps is obtained as a value common to all heat generating elements.

When printing the image data, the control unit 5 calculates the heat generation time Sn for each heat generation element by the calculation unit 51, and controls each heat generation element of the thermal head 10 based on the calculated heat generation time Sn. The control unit 5 also controls the paper transport unit 8 based on the print speed Ps based on the print mode. The history storage unit 31 of the storage unit 3 stores the history information of the heat generation time Sn and the history information of the printing speed Ps of each heat generating element of the thermal head 10.

The amount of ink residue generated by the heat generation time Sn and the printing speed Ps from the equation (1) is obtained in advance by an experiment, and a LUT (look-up table) for each parameter (heat generation time Sn and printing speed Ps) is obtained. It may be created and stored in the history storage unit 31. In this way, the amount of ink residue generated can be easily obtained by referring to the LUT.

<Print control in thermal transfer printer>
FIG. 4 is a flowchart showing a printing process in the thermal transfer printer 1 including prediction of printing defects due to ink residue. Hereinafter, this printing process will be described step by step.

First, the prediction unit 52 of the control unit 5 reads out the history information of the heat generation time Sn of each heat generating element of the thermal head 10 and the history information of the printing speed Ps (contact speed of the ink sheet 9) from the history storage unit 31 (step). S101).

Next, the calculation unit 51 of the control unit 5 acquires the temperature Th of the thermal head 10 from the thermal head temperature sensor 10a, acquires the internal temperature Tk of the thermal transfer printer 1 from the internal temperature sensor 19, and heat transfers from the internal humidity sensor 20. The internal humidity Hk of the printer 1 is acquired (step S102).

Next, the calculation unit 51 of the control unit 5 selects and reads the image data I to be printed stored in the temporary storage memory of the storage unit 3 (step S103). Then, the calculation unit 51 of the control unit 5 calculates the heat generation time Sn for each heat generating element from the mathematical formula (1) from the image data I, the temperature Th of the thermal head 10, the internal temperature Tk, and the internal humidity Hk.

Next, the prediction unit 52 of the control unit 5 generates ink residue when printing the image data selected in step S103 from the heat generation time Sn calculated by the calculation unit 51 and the print speed Ps of the designated print mode. Is calculated (step S104).

Further, the prediction unit 52 of the control unit 5 uses the history information of the heat generation time Sn of each heat generating element of the thermal head 10 read from the history storage unit 31 in step S101 and the history information of the printing speed Ps to determine the ink residue in the thermal head 10. The accumulated amount is calculated (step S105).

Next, the predicted accumulation amount of ink residue for each light emitting element is obtained by summing the amount of ink residue generated in step S104 and the amount of ink residue accumulated calculated in step S105. The predicted accumulation amount of ink residue is the amount of ink residue that is expected (estimated) to be accumulated in each heat generating element of the thermal head 10 when the image data to be printed is printed.

Then, the prediction unit 52 of the control unit 5 compares the calculated predicted accumulation amount of ink residue for each light emitting element with the limit accumulation amount at which printing defects occur due to the ink residue, and the predicted accumulation amount for each light emitting element. The difference (margin) between the limit and the limit accumulation amount is obtained (step S106). The limit accumulation amount is an amount in which if the accumulation amount of ink residue exceeds this even in one of the light emitting elements, printing defects such as missing dots or printing scratches occur. The limit storage amount is stored in, for example, the non-volatile memory of the storage unit 3.

Next, the print control unit 53 of the control unit 5 selects a printing method in which printing defects are less likely to occur based on the margin for each light emitting element obtained in step S106, and prints image data by the printing mechanism in that printing method. Print (step S107). That is, printing is performed by a printing method in which the difference between the maximum value of the predicted accumulation amount of ink residue for each heat generating element and the limit accumulation amount becomes larger.

After the printing by the printing mechanism is completed, the control unit 5 updates the heat generation time history information and the printing speed history information for each heat generating element of the thermal head 10 and saves them in the history storage unit 31 (step S108).

<Selection of printing method>
5A, 5B, and 5C are diagrams for explaining an example of a printing method selection method in step S107 of FIG. FIG. 5A is a graph showing the predicted accumulation amount of ink residue obtained from the history information of the heat generation time Sn and the history information of the printing speed Ps of each of the N heat generating elements of the thermal head 10. The horizontal axis of FIG. 5A shows the arrangement of heat generating elements (1st to Nth), and the vertical axis shows the accumulated amount of ink residue.

As shown in FIG. 5A, it is assumed that the largest amount of ink residue is attached to the nth heat generating element among the N heat generating elements of the thermal head 10. In FIG. 5A, the limit accumulation amount of ink residue is shown by a broken line. If the accumulated amount of ink residue exceeds this limit accumulated amount, printing defects such as missing dots or printing scratches occur.

A case where the image data shown in FIG. 5B is printed in this state will be described. FIG. 5B is a diagram showing image data to be printed from now on. The horizontal axis shows the position in the arrangement direction of the heat generating elements, and the vertical axis shows the position in the printing direction (the transport direction of the paper 7 in FIG. 1). Is shown.

The image data shown in FIG. 5B has gradation data (high density area) having a high print density at a position corresponding to the nth heat generating element. When this image data is printed, since the heat generation time Sn of the nth heat generation element is long, the predicted accumulation amount of ink residue in the nth heat generation element approaches the limit accumulation amount.

Therefore, the control unit 5 of the thermal transfer printer 1 does not print the image data of FIG. 5 (B) as it is, but rotates the direction of the image data by 180 degrees and prints it as the image data shown in FIG. 5 (C). .. FIG. 5C is a 180-degree rotation of the image data of FIG. 5B. In the image data of FIG. 5C, the high density area having a high print density is located at a position corresponding to another heat generating element (for example, the fifth heat generating element), and is located at a position corresponding to the nth heat generating element. There is an area with low print density.

By doing so, the heat generation time Sn of the nth heat generating element can be shortened, so that the decrease in the difference (margin) between the predicted accumulation amount and the limit accumulation amount of ink residue in the nth heat generation element is suppressed. be able to. That is, it is possible to prevent printing defects caused by ink residue from occurring.

As described above, the control unit 5 (print control unit 53) of the thermal transfer printer 1 has a printing method in which the difference between the maximum value of the predicted accumulation amount of ink residue obtained by the prediction unit 52 and the limit accumulation amount becomes larger (here, the image). Select (Data orientation) and print using that printing method.

When the difference (margin) between the maximum value of the predicted accumulation amount of ink residue (for example, the predicted accumulation amount in the Nth heat generating element shown in FIG. 5A) and the limit accumulation amount is larger than the threshold value, for example, ink residue. When the maximum value of the predicted accumulation amount is 50% or less of the limit accumulation amount, it is unlikely that printing defects due to ink residue will occur immediately, and thus are shown in FIGS. 5 (B) and 5 (C). Do not rotate the image data like this.

<Effect of Embodiment 1>
As described above, in the first embodiment of the present invention, the predicted accumulation amount of ink residue for each heat generating element is obtained based on the history information and the image data of the heat generation time Sn for each heat generating element of the thermal head 10, and the predicted accumulation is performed. Printing is performed by selecting a printing method according to the difference (margin) between the amount and the limit accumulated amount. Therefore, it is possible to suppress the occurrence of printing defects due to the accumulation of ink residue and maintain good print quality for a long period of time. In addition, the number of sheets that can be printed increases before the life of the heat generating element of the thermal head 10. Further, the user does not need to frequently clean the thermal head 10 and replace parts, which improves convenience.

Further, in order to obtain the predicted accumulation amount of ink residue based on the history information of the printing speed Ps in addition to the history information of the heat generation time Sn for each heat generating element, a plurality of printing speeds (paper) corresponding to the high speed mode, the high quality mode, etc. are obtained. In a thermal transfer printer having a transport speed of 7), the predicted accumulation amount of ink residue can be calculated more accurately.

In addition, in order to select the orientation of the image data so that the difference between the predicted accumulation amount of ink residue and the limit accumulation amount becomes larger, the high density area of the image density is printed with a heat generating element having a relatively small predicted accumulation amount of ink residue. By doing so, the occurrence of printing defects can be effectively suppressed.

In addition, since the printing method (for example, the orientation of image data) is selected so that the difference between the maximum value of the predicted accumulation amount of ink residue and the limit accumulation amount becomes larger, the heat generation amount of the heat generating element in which the ink residue is most accumulated is determined. It can be effectively suppressed.

First modification.
In the first embodiment described above, the predicted accumulation amount of ink residue in each heat generating element was obtained based on the history information and image data of the heat generation time Sn and the printing speed Ps of each heat generating element. On the other hand, in addition to the history information of the heat generation time Sn and the printing speed Ps of each heat generating element, the predicted accumulation amount of ink residue in each heat generating element may be obtained based on the information of the ink sheet 9. This is because the heat resistance and abrasion resistance of the base film 9e or the heat-resistant slippery layer 9f differ depending on the type of the ink sheet 9.

FIG. 6 is a graph showing the predicted accumulation amount of ink residue for each heat generating element of the thermal head, the horizontal axis shows the arrangement of the heat generating elements, and the vertical axis shows the predicted accumulation amount of ink residue. FIG. 6 shows data of two types of ink sheets 9 having different wear resistances of the heat-resistant slipping layer 9f. The curve A1 (solid line) shows the data of the ink sheet 9 having a lower wear resistance of the heat-resistant slip layer 9f, and the curve A2 (broken line) shows the data of the ink sheet 9 having a higher wear resistance of the heat-resistant slip layer 9f. Show the data.

In the ink sheet 9, the higher the wear resistance of the heat-resistant slipping layer 9f, the less ink residue is generated when printing is performed under the same conditions. Therefore, the predicted accumulation amount of ink residue for each heat generating element is smaller in the ink sheet 9 (curve A2) having higher wear resistance of the heat-resistant slipping layer 9f. Therefore, the prediction unit 52 of the control unit 5 obtains the predicted accumulation amount of ink residue in consideration of the type of the ink sheet 9 in addition to the history information of the heat generation time Sn and the printing speed Ps of each heat generating element of the thermal head 10. Is desirable.

The ink sheet 9 is provided with an IC tag (sheet information storage unit) using, for example, an RFID (Radio Frequency ID), and stores information indicating the type of the ink sheet 9. By reading this information with the ink sheet information sensor 21 (FIGS. 1 and 2), information indicating the type of the ink sheet 9 can be acquired.

The prediction unit 52 of the control unit 5 sets the type of ink sheet 9 by setting a coefficient for obtaining the accumulated amount of ink residue for each heat generating element according to the type of ink sheet 9 acquired from the ink sheet information sensor 21, for example. The predicted accumulation amount of ink residue is calculated by reflecting the difference in the wear resistance of the heat-resistant slippery layer 9f according to the above. This coefficient can be obtained in advance by conducting an experiment with, for example, a plurality of types of ink sheets 9 having different wear resistance of the heat-resistant slippery layer 9f, and can be stored in the non-volatile memory of the storage unit 3. Further, the wear resistance of the heat-resistant slip layer 9f is not limited, and the heat resistance of the heat-resistant slip layer 9f and the wear resistance or heat resistance of the base film 9e may be reflected.

As described above, in the first modification, since the predicted accumulation amount of ink residue is obtained based on the information of the ink sheet 9, the predicted accumulation amount of ink residue can be obtained with higher accuracy, and printing defects are effectively reduced. can do.

Second modification.
In the first embodiment described above, the orientation of the image data is selected and printed so that the difference between the predicted accumulation amount of ink residue and the limit accumulation amount becomes larger, but when printing a plurality of image data in succession. The printing order of the image data may be changed according to the image density.

7 (A) and 7 (B) are schematic views showing the printing order of image data in the second modification. Here, it is assumed that the seven image data A to G shown in FIG. 7A are input to the thermal transfer printer 1. The 1st to 4th image data A, B, C, and D have a high image density, and the 5th to 7th image data E, F, and G have a low image density.

When image data A, B, C, and D having a high image density are continuously printed, the temperature of each heat generating element of the thermal head 10 tends to rise. When the temperature of each heat generating element of the thermal head 10 rises, the peeling of the heat-resistant slipping layer 9f due to friction between each heat generating element and the ink sheet 9 may increase.

Therefore, among the heat generating elements of the thermal head 10, there is a heat generating element (for example, the nth heat generating element shown in FIG. 5A) in which the difference (margin) between the predicted accumulation amount of ink residue and the limit accumulation amount is small. In this case, the printing order of the image data A to G is changed, and the image data A, B, C, D having a high image density and the image data E, F, G having a low image density are printed alternately. That is, as shown in FIG. 7B as an example, image data A, image data E, image data B, image data F, image data C, image data G, and image data D are printed in this order.

By preventing continuous printing of image data with a high image density in this way, it is possible to suppress a temperature rise of each heat generating element of the thermal head 10, thereby causing friction between each heat generating element and the ink sheet 9. It can be reduced. As a result, it is possible to suppress a further increase in the accumulated amount of ink residue in each heat generating element of the thermal head 10 (particularly, a heat generating element having a small difference between the predicted accumulated amount of ink residue and the limit accumulated amount) and suppress the occurrence of printing defects. Can be done.

If the difference between the maximum value of the predicted accumulation amount of ink residue and the limit accumulation amount in the heat generating element of the thermal head 10 is larger than the threshold value, the image data A to G are printed as they are without changing the printing order. ..

Here, an example in which image data A, B, C, D having a high image density and image data E, F, G having a low image density are printed alternately has been described, but the example is not limited to such an example. Absent. If image data having a relatively low image density is printed between two or more image data having a relatively high image density, the temperature rise of each heat generating element of the thermal head 10 can be suppressed to some extent, resulting in printing defects. It is a plus in suppressing the occurrence of.

As described above, in the second modification, the printing order of the image data is changed according to the shading of the image density, so that each of the thermal heads 10 by continuously printing the image data having a high image density. It is possible to suppress the temperature rise of the heat generating element, thereby reducing the friction between each heat generating element and the ink sheet 9. As a result, it is possible to suppress a further increase in the amount of ink residue accumulated in each heat generating element of the thermal head 10, and to suppress the occurrence of printing defects.

The second modification may be combined with the first embodiment, the first modification, or both. That is, the predicted accumulation amount of ink residue is obtained based on the information of the ink sheet, and when there is a heat generating element in which the difference between the predicted accumulation amount and the limit accumulation amount is small, the orientation of the image data or the printing order is changed. It may be controlled to.

Third modified example.
In the first embodiment described above, the orientation of the image data is selected and printed so that the difference between the predicted accumulation amount of ink residue and the limit accumulation amount becomes larger, but the heat generating element of the thermal head 10 is printed according to the image density. The amount of electricity and the printing speed may be changed. Here, the amount of energization corresponds to the value of the current flowing through the heat generating element (heating resistor). The printing speed is the transport speed of the paper 7 by the paper transport unit 8 shown in FIG.

8 (A) and 8 (B) are schematic views showing a method of energization control (heat generation control) of each heat generating element of the thermal head 10 in the third modification, where the horizontal axis represents time and the vertical axis represents unit. Indicates the amount of energization per hour. Here, it is assumed that three image data A, B, and C are printed.

In the energization control shown in FIG. 8A, the heat generation time of each heat generating element of the thermal head 10 is T1, and the energization amount per unit time is E1. On the other hand, in the energization control shown in FIG. 8 (B), the heat generation time of each heat generating element is doubled (that is, 2 × T1) and the energization amount per unit time is 0.5 as compared with FIG. 8 (A). It is doubled (that is, 0.5 x E1).

The amount of heat per heating element (that is, per unit area) of the thermal head 10 is the product of the amount of energization and the energization time. Therefore, in the energization control shown in FIG. 8 (B), the printing speed (conveying speed of the paper 7) is 1/2 that of the energization control shown in FIG. 8 (A), but the amount of heat per heat generating element is It is the same.

By slowing down the printing speed as shown in FIG. 8 (B), the printing time is lengthened, but the energization amount of the heat generating elements of the thermal head 10 is reduced, and the heat generating elements of the thermal head 10 and the ink sheet 9 are also reduced. Since the frictional contact speed with the ink is reduced, the accumulation of ink residue in the thermal head 10 can be suppressed.

For example, among the heat generating elements of the thermal head 10, there is a heat generating element having a small difference (margin) between the predicted accumulation amount of ink residue and the limit accumulation amount (for example, the nth heat generating element shown in FIG. 5A). In this case, by selecting the energization control shown in FIG. 8B, it is possible to suppress the occurrence of printing defects due to ink residue.

Further, when the difference between the maximum value of the predicted accumulation amount of ink residue and the limit accumulation amount in the heat generating element of the thermal head 10 is larger than the threshold value, the printing time can be obtained by selecting the energization control shown in FIG. 8 (A). Can be shortened.

Here, an example of switching the energization amount and the printing speed of each heat generating element in two ways shown in FIGS. 8A and 8B has been described, but it may be switched in three or more ways.

As described above, in the third modification, printing is executed by selecting the energization amount and the printing speed of each heat generating element according to the difference between the predicted accumulation amount and the limit accumulation amount of ink residue in the thermal head 10. Therefore, the occurrence of printing defects can be effectively suppressed. Further, when the amount of accumulated ink residue in each heat generating element of the thermal head 10 is small, the printing speed can be increased to shorten the printing time.

In addition, this third modification may be combined with one or more of the first embodiment, the first modification and the second modification. For example, the predicted accumulation amount of ink residue may be obtained based on the information of the ink sheet, and the printing speed may be slowed down when there is a heat generating element in which the difference between the predicted accumulation amount and the limit accumulation amount is small. Further, the orientation of the image data, the printing order, or both may be switched according to the difference between the predicted accumulation amount of ink residue and the limit accumulation amount in the thermal head, and the printing speed may be further switched.

Embodiment 2.
Next, Embodiment 2 of the present invention will be described. In the first embodiment described above, the thermal transfer printer 1 performs the printing process under the control of its own control unit 5. On the other hand, in the second embodiment, the printing system 100 including the plurality of thermal transfer printers 201 and 301 and the information processing apparatus 400 will be described.

FIG. 9 is a block diagram showing a print system 100 according to a second embodiment of the present invention. As shown in FIG. 9, the print system 100 includes two thermal transfer printers 201 and 301 and an information processing device 400. The number of thermal transfer printers in the printing system 100 may be three or more.

The thermal transfer printer 201 includes a communication unit 202, a storage unit 203, an image processing unit 204, a control unit 205, a paper transport unit 208, a thermal head 210, a cutter 212, a paper discharge unit 213, a supply bobbin drive unit 215, and a take-up bobbin drive unit. It includes a 217, a bus 218, an internal temperature sensor 219, an internal humidity sensor 220, and an ink sheet information sensor 221. It also includes a platen roller 11, a supply bobbin 14, and a take-up bobbin 16 (all of which are shown in FIG. 1), which are not shown in FIG. These components are configured in the same manner as the thermal transfer printer 1 (FIGS. 1 and 2) of the first embodiment except for the control unit 205.

Similarly, the thermal transfer printer 301 includes a communication unit 302, a storage unit 303, an image processing unit 304, a control unit 305, a paper transport unit 308, a thermal head 310, a cutter 312, a paper discharge unit 313, a supply bobbin drive unit 315, and a take-up unit. It includes a bobbin drive unit 317, a bus 318, an internal temperature sensor 319, an internal humidity sensor 320, and an ink sheet information sensor 321. It also includes a platen roller 11, a supply bobbin 14, and a take-up bobbin 16 (all of which are shown in FIG. 1), which are not shown in FIG. These components are configured in the same manner as the thermal transfer printer 1 (FIGS. 1 and 3) of the first embodiment except for the control unit 305.

The control unit 205 of the thermal transfer printer 201 and the control unit 305 of the thermal transfer printer 301 are all composed of a processor including a CPU, etc., but the calculation unit 51, the prediction unit 52, and the print control unit 53 (see FIG. 2). It is different from the control unit 5 of the first embodiment in that it does not have.

The information processing device 400 is communicably connected to the communication units 2 of the thermal transfer printers 201 and 301 by the network 102. Further, the information processing apparatus 400 predicts that the calculation unit 401 that calculates the heat generation time for each heat generating element of the thermal heads 210 and 310 and the occurrence of printing defects due to ink residue for each of the heat generating elements of the thermal heads 210 and 310 are predicted. It has a unit 402 and a print control unit 403 that controls the printing operation of the thermal transfer printers 201 and 301 based on the prediction result of the prediction unit 402.

That is, in the second embodiment, the components (calculation unit 401, prediction unit) corresponding to the calculation unit 51, the prediction unit 52, and the print control unit 53 (FIG. 2) of the control unit 5 of the thermal transfer printer 1 of the first embodiment. 402 and the print control unit 403) are provided in the information processing apparatus 400. The print control unit 403 of the information processing apparatus 400 transmits image data and information related to printing to the thermal transfer printers 201 and 301.

The calculation unit 401, the prediction unit 402, and the print control unit 403 may be realized, for example, by the processor executing a program stored in the memory, or may be realized by a hardware circuit (processing circuit). Good.

<Print control in print system>
FIG. 10 is a flowchart showing a printing process in the printing system 100 including prediction of printing defects due to ink residue. Hereinafter, this printing process will be described step by step.

The prediction unit 402 of the information processing device 400 is used to display historical information on the heat generation time Sn (energization time) of each heat generating element of the thermal head 10 from the history storage units 203a and 303a of the storage units 203 and 303 of the thermal transfer printers 201 and 301, respectively. And the history information of the printing speed Ps is read (step S201).

Next, the calculation unit 401 of the information processing apparatus 400 uses the thermal head temperature sensor 210a, the internal temperature sensor 219, and the internal humidity sensor 220 of the thermal transfer printer 201 to obtain the temperature Th of the thermal head 210, the internal temperature Tk of the thermal transfer printer 201, and the inside. Obtain the humidity Hk. Further, the temperature Th of the thermal head 310, the internal temperature Tk and the internal humidity Hk of the thermal transfer printer 301 are acquired from the thermal head temperature sensor 310a, the internal temperature sensor 319 and the internal humidity sensor 320 of the thermal transfer printer 301 (step S202).

Next, the calculation unit 401 of the information processing apparatus 400 selects the image data to be printed (S203). The image data to be printed is, for example, image data input to the information processing device 400 by the user and designated for printing. Further, the calculation unit 401 of the information processing apparatus 400 generates heat from the thermal heads 210 and 310 from the image data I, the temperatures Th of the thermal heads 210 and 310, the internal temperatures Tk of the thermal transfer printers 201 and 301, and the internal humidity Hk. The heat generation time Sn for each element is calculated.

Next, the prediction unit 402 of the information processing apparatus 400 selects the thermal heads 210 and 310 from the heat generation time Sn calculated by the calculation unit 401 and the print speed Ps of the designated print mode in step S203. The amount of ink residue generated when the image data is printed is calculated (step S204).

Further, the prediction unit 402 of the information processing apparatus 400 uses thermal information from the heat generation time Sn history information and the print speed Ps history information of the heat generation elements of the thermal heads 210 and 310 read from the history storage units 203a and 303a in step S201. The amount of ink residue accumulated in the heads 210 and 310 is calculated (step S205).

Next, by summing the amount of ink residue generated in step S204 and the amount of ink residue accumulated calculated in step S205, the predicted accumulation amount of ink residue for each light emitting element is obtained for each of the thermal heads 210 and 310. ..

Then, the prediction unit 402 of the information processing apparatus 400 compares the calculated predicted accumulation amount of ink residue for each light emitting element with the limit accumulation amount at which printing defects occur due to the ink residue, and compares each of the thermal heads 210 and 310. The difference (margin) between the predicted accumulation amount and the limit accumulation amount is obtained for each light emitting element (step S206).

Next, the print control unit 403 of the information processing apparatus 400 selects a thermal transfer printer, which is less likely to cause printing defects, from the thermal transfer printers 201 and 301, based on the margin obtained by the prediction unit 402 in step S206. Image data is printed on the selected thermal transfer printer (step S207). That is, among the thermal transfer printers 201 and 301, the thermal transfer printer having a large difference between the maximum value of the predicted accumulation amount of ink residue and the limit accumulation amount is selected, and printing is performed with the thermal transfer printer.

After the printing by the selected thermal transfer printer is completed, the information processing apparatus 400 updates and saves the heat generation time history information and the printing speed history information for each heat generating element of the thermal head in the history storage unit of the thermal transfer printer. (Step S208).

<Selection of thermal transfer printer>
11A, 11B, and 11C are diagrams for explaining an example of a method of selecting a thermal transfer printer in step S207 of FIG. FIG. 11A is a graph showing the predicted accumulation amount of ink residue obtained from the history information of the heat generation time Sn of each heat generating element of the thermal head 210 of the thermal transfer printer 201 and the history information of the printing speed Ps. Similarly, FIG. 11B is a graph showing the predicted accumulation amount of ink residue obtained from the history information of the heat generation time Sn and the history information of the printing speed Ps of each heat generating element of the thermal head 310 of the thermal transfer printer 301.

In FIGS. 11A and 11B, the horizontal axis represents the arrangement of heat generating elements (1st to Nth), and the vertical axis represents the amount of ink residue accumulated. Further, in FIGS. 11A and 11B, the limit accumulation amount is shown by a broken line. As described in the first embodiment, the limit accumulation amount is an amount in which printing defects such as missing dots or printing scratches occur when the accumulation amount of ink residue exceeds this even in one of the heat generating elements. The limit storage amount of the thermal transfer printer 201 is stored in the non-volatile memory of the storage unit 203, and the limit storage amount of the thermal transfer printer 301 is stored in the non-volatile memory of the storage unit 303.

As shown in FIG. 11A, in the thermal transfer printer 201, the accumulated amount of ink residue in the nth light emitting element of the thermal head 210 is the maximum, and the difference (margin) from the limit accumulated amount is small. On the other hand, as shown in FIG. 11B, in the thermal transfer printer 301, the accumulated amount of ink residue in the 1st to Nth light emitting elements of the thermal head 310 is even and at a low level (that is, the limit accumulated amount). The difference is large).

A case where the image data shown in FIG. 11C is printed in this state will be described. FIG. 11C is a diagram showing image data to be printed from now on. The horizontal axis shows the position in the arrangement direction of the heat generating elements, and the vertical axis shows the position in the printing direction (the transport direction of the paper 7 in FIG. 1). Is shown.

The image data shown in FIG. 11C has gradation data (high density area) having a high print density at a position corresponding to the nth heat generating element. Therefore, when this image data is printed, the heat generation time Sn of the nth heat generation element is long, so that the predicted accumulation amount of ink residue in the nth heat generation element approaches the limit accumulation amount.

Therefore, the prediction unit 402 of the information processing apparatus 400 predicts the amount of ink residue generated when the image data shown in FIG. 11C is printed by the thermal transfer printers 201 and 301, respectively, and predicts the amount of ink residue accumulated and the limit accumulation. The image data is printed by selecting the thermal transfer printer (here, thermal transfer printer 301) having a larger difference (margin) from the amount. As a result, the accumulation of ink residue can be suppressed, and the occurrence of printing defects can be effectively suppressed.

When the difference between the maximum value of the predicted accumulation amount of ink residue (for example, the predicted accumulation amount in the Nth heat generating element shown in FIG. 11A) and the limit accumulation amount is larger than the threshold value, for example, the predicted accumulation amount of ink residue. When the maximum value of is 50% or less of the limit accumulation amount, it is unlikely that printing defects due to ink residue will occur regardless of which thermal transfer printer 201 or 301 prints, so other conditions (for example, use). The thermal transfer printers 201 and 301 are selected according to the person's designation, etc.).

<Effect of Embodiment 2>
As described above, in the second embodiment of the present invention, the predicted accumulation amount of ink residue in the plurality of thermal transfer printers 201 and 301 is compared, and a thermal transfer printer having a larger difference between the predicted accumulation amount and the limit accumulation amount is selected. Since the image data is printed, it is possible to suppress the occurrence of printing defects due to the accumulation of ink residue and maintain good print quality for a long period of time. In addition, the number of sheets that can be printed increases before the life of the heat generating element of the thermal head 10. Further, since it is not necessary to frequently clean the thermal head 10 and replace parts, convenience is improved.

Further, since the image data is printed by selecting a thermal transfer printer (thermal transfer printer 301 in the example of FIG. 11) in which the predicted accumulation amount of ink residue for each heat generating element of the thermal head is more uniform, the accumulation amount of ink residue is set from the limit accumulation amount. Can be kept low, and the occurrence of printing defects can be effectively suppressed.

It should be noted that the second embodiment may be combined with one or more of the first embodiment and the first to third modifications. For example, a thermal transfer printer having a larger difference between the predicted accumulation amount of ink residue and the limit accumulation amount may be selected from a plurality of thermal transfer printers, and the orientation of image data, the printing order, or the printing speed may be selected. Further, the predicted accumulation amount of ink residue may be obtained based on the information of the ink sheet.

Although the preferred embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various improvements or modifications are made without departing from the gist of the present invention. be able to.

1,201,301 Thermal transfer printer, 2,201,301 communication unit, 3,203,303 storage unit, 31,203a, 303a history storage unit, 4,204,304 image processing unit, 5,205,305 control unit, 51 Calculation unit, 52 Prediction unit, 53 Print control unit, 7 Paper, 8 Paper transport unit, 9 Ink sheet, 10 Thermal head, 10a Thermal head temperature sensor, 11 Platen roller, 12 Cutter, 13 Paper discharge unit, 14 Supply bobbin , 16 take-up bobbin, 18 ink sheet information sensor, 19 internal temperature sensor, 20 internal humidity sensor, 100 print system, 400 information processing device, 401 calculation unit, 402 prediction unit, 403 print control unit.

Claims (13)

A transport unit that transports paper and
A platen roller that crimps the ink sheet and the paper,
A thermal head having a plurality of heat generating elements arranged in one direction, arranged opposite to the platen roller, heating the ink sheet, and transferring the ink of the ink sheet to the paper.
A history storage unit that stores history information of heat generation time for each heat generating element of the thermal head,
Based on the history information and image data stored in the history storage unit, a prediction unit for obtaining a predicted accumulation amount of ink residue for each heat generating element of the thermal head, and a prediction unit.
A thermal transfer printer including a print control unit that performs print control based on the predicted accumulation amount obtained by the prediction unit. The predicted accumulated amount is
The amount of ink residue already accumulated in each heat generating element of the thermal head and
The thermal transfer printer according to claim 1, wherein the total is the total amount of ink residue expected to be accumulated in each heat generating element of the thermal head by printing the image data. The thermal transfer printer according to claim 1 or 2, wherein the history information stored in the history storage unit also includes history information of the transfer speed of the paper by the transfer unit. From claim 1, the print control unit performs print control so that the difference between the predicted accumulation amount obtained by the prediction unit and the limit accumulation amount of ink residue in which printing defects occur becomes large. The thermal transfer printer according to any one of up to 3. The thermal transfer printer according to any one of claims 1 to 4, wherein the print control unit selects the orientation of the image data based on the predicted accumulation amount obtained by the prediction unit. The thermal transfer according to any one of claims 1 to 5, wherein the print control unit selects the printing order of the image data based on the predicted accumulation amount obtained by the prediction unit. Printer. The method according to any one of claims 1 to 6, wherein the print control unit selects the transfer speed of the paper by the transfer unit based on the predicted accumulation amount obtained by the prediction unit. Thermal transfer printer. A thermal head temperature measuring unit that measures the temperature of the thermal head,
An internal temperature measuring unit that measures the internal temperature of the thermal transfer printer,
An internal humidity measuring unit that measures the internal humidity of the thermal transfer printer,
It is further provided with a calculation unit that calculates the heat generation time for each heat generating element of the thermal head based on the temperature of the thermal head, the internal temperature and internal humidity of the thermal transfer printer, and the image data. The thermal transfer printer according to any one of claims 1 to 7. Further equipped with an ink sheet information sensor for reading the ink sheet information,
Any of claims 1 to 8, wherein the prediction unit obtains a predicted accumulation amount of ink residue for each heat generating element of the thermal head based on the history information, the image data, and the information of the ink sheet. The thermal transfer printer according to item 1. Equipped with multiple thermal transfer printers and information processing equipment
All of the plurality of thermal transfer printers
A transport unit that transports paper and
A platen roller that crimps the ink sheet and the paper,
A thermal head having a plurality of heat generating elements arranged in one direction, arranged opposite to the platen roller, heating the ink sheet to transfer the ink of the ink sheet to the paper, and each heat generating element of the thermal head. Equipped with a history storage unit that stores history information of heat generation time
The information processing device
For each of the plurality of thermal transfer printers, a prediction unit for obtaining a predicted accumulation amount of ink residue for each heat generating element of the thermal head based on the history information and image data stored in the history storage unit.
A printing system including a print control unit that selects one of the plurality of thermal transfer printers to execute printing based on the predicted accumulation amount obtained by the prediction unit. The print control unit selects and prints from the plurality of thermal transfer printers, the thermal transfer printer having a large difference between the predicted accumulation amount obtained by the prediction unit and the limit accumulation amount of ink residue in which printing defects occur. The printing system according to claim 10, wherein the printing system is characterized by the above. The printing system according to claim 10 or 11, wherein the history information stored in the history storage unit includes history information of the transfer speed of the paper by the transfer unit. All of the plurality of thermal transfer printers
A thermal head temperature measuring unit that measures the temperature of the thermal head,
An internal temperature measuring unit that measures the internal temperature of the thermal transfer printer,
It has an internal humidity measuring unit that measures the internal humidity of the thermal transfer printer.
The information processing apparatus generates heat for each heat generating element of the thermal head based on the temperature of the thermal head, the internal temperature and internal humidity of the thermal transfer printer, and the image data for each of the plurality of thermal transfer printers. The printing system according to any one of claims 10 to 12, wherein the printing system has a calculation unit for calculating time.

Images