JP2006192757A - Sublimation type thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sublimation type thermal printer capable of preventing occurrence of a trailing phenomenon without increasing the recording time period. <P>SOLUTION: Data of gradation levels 1, 2,..., 255 involved in gradation data are set to latch circuits 21 in the above order in a constant cycle through a shift register 20. In the data of gradation level m, a bit corresponding to a pixel not smaller than the gradation level m is "1" and a bit corresponding to a pixel smaller than the gradation level m is "0". As a result, a heating resister element R connected to a driver circuit 22 in a system to which "1" is set, is energized. Firstly, a voltage of 22 volts is applied to the heating resister element R. When the energizing time period to the heating resister element R exceeds a predetermined time period, a voltage of 15 volts is supplied to the heating resister element R in order to eliminate influence of accumulation of heat on a thermal head 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sublimation type thermal printer that records an image corresponding to a gradation level on a recording sheet by changing a sublimation amount of a sublimation dye.

  Conventionally, by controlling the energization amount to each heating resistor element of a thermal head in which a plurality of heating resistor elements are arranged in a line, the sublimation amount of the sublimable dye is changed to record an image according to the gradation level. There are sublimation thermal printers that record on paper. In this printer, as the temperature of the thermal head increases, the image density increases even if the energization amount of the heating resistor elements is the same. For this reason, if each line of the recording paper is continuously recorded, the heat generated when the previous line is recorded is accumulated in the thermal head. Part blurring (hereinafter referred to as tailing phenomenon) may occur.

  Therefore, in the following Patent Document 1, it is proposed to prevent the tailing phenomenon from occurring as follows. FIG. 5 is a block diagram showing the configuration of a conventional thermal head, and FIG. 6 is a time chart showing the operation of the conventional thermal head. In FIG. 5, RR (such as RR1) is a heating resistor element, 51 is a driver circuit that drives the heating resistor element RR, 53 is a shift register that takes in gradation data of gradation levels 1 to 255 by a shift clock, and 52 is a shift register. 53 is a latch circuit that latches an output signal of 53 with a latch signal. One end of the heating resistor element RR is connected to the power supply line Vp.

  The data of each gradation level of the gradation data (such as data (1) shown in FIG. 4) is composed of a bit string having the same number of bits as the number of heating resistance elements RR. In data (1), the bit corresponding to a pixel having a gradation level of 1 or more is 1, and the bit corresponding to a pixel having a gradation level of 0 is 0. In the data (255), the bit corresponding to the pixel having the gradation level of 255 is 1, and the bit corresponding to the pixel having the gradation level of 254 or less is 0. That is, in the data (m), the bit corresponding to a pixel having a gradation level of m or higher is 1 and the bit corresponding to a pixel having a gradation level of less than m is 0. Data of each gradation level is taken into the shift register 53 by the shift clock and further set in the latch circuit 52. When the strobe signal is low and the non-inverting input terminal is high, the output terminal of the driver circuit 51 becomes low, the current from the power supply line Vp flows through the heating resistor element RR, and the heating resistor element RR is energized. .

  Since the data of each gradation level is as described above, the energization periods of the heating resistance elements RR at the gradation levels 255, 2 and 1 are as shown in FIGS. 6 (d) to 6 (f), respectively. Also, the pause time Td is included in the recording time Tc for one line. The pause time Td is a time from the end of the energization period of the gradation level 255 to the start of recording of the next line. During this period, no heating resistance element is energized. By providing the pause time Td in this way, the thermal storage of the thermal head is eliminated and the above-mentioned tailing phenomenon does not occur.

Although the image corresponding to the gradation level is not recorded on the recording paper, the following Patent Document 2 discloses that in order to improve the reliability and the life of the thermal head provided with a heating element for coloring the thermal paper. It is shown that a pulse having a waveform whose voltage decreases with time is applied to the heating element.
JP-A-5-345437 (Claim 1, paragraphs 0019 to 0031, paragraph 0041, FIG. 3) JP 58-118276 A (Claims)

  However, the one disclosed in Patent Document 1 has a problem that the recording time Tc for one line becomes long because the pause time Td is provided. In Patent Document 1, it is described that the pause time Td is 40% or less of the recording time Tc. However, if the pause time Td is 40%, the recording time Tc is smaller than when the pause time Td is not provided. 1.7 times (1 ÷ 0.6).

  SUMMARY OF THE INVENTION The present invention solves the above problems, and an object of the present invention is to provide a sublimation type thermal printer that can prevent the occurrence of a tailing phenomenon without increasing the recording time. is there.

  In the first aspect of the present invention, the sublimation amount of the sublimation dye is changed by controlling the energization amount to each heating resistance element of the thermal head in which a plurality of heating resistance elements are arranged in a line, and according to the gradation level. In a sublimation type thermal printer that records a recorded image on recording paper, the gradation level data is composed of data of each gradation level including a signal indicating that the pixel is above the gradation level and a signal indicating that the pixel is below the level. An energization means for energizing a heating resistor element corresponding to a pixel of a tone level or higher for a certain period of time and performing energization using data of each gradation level in order from gradation level 1 to the maximum gradation level; and a first voltage And a power supply circuit that outputs a second voltage lower than the first voltage, and a voltage supply unit that supplies either the first voltage or the second voltage output from the power supply circuit to the heating resistor element.When recording one line, the first voltage is supplied to the heating resistor element during the period when the gradation level is lower than the predetermined level, and the first voltage is supplied to the heating resistor element during the period when the gradation level is higher than the predetermined level. Supply two voltages.

  Here, the energizing means corresponds to the CPU, control circuit, shift register, latch circuit, and driver circuit described in the embodiment.

  As described above, the energization amount of the heating resistor element (drive power) is reduced by lowering the voltage supplied to the heating resistor element when the gradation level exceeds a predetermined level so as not to be affected by the thermal storage of the thermal head. ) Is reduced, the thermal storage of the thermal head is suppressed, and the occurrence of the tailing phenomenon due to the above-mentioned thermal storage can be prevented. Further, the problem of the tailing phenomenon is not solved by providing a pause time as in Patent Document 1, but the problem is solved by lowering the supply voltage to the heating resistor element. The power consumption can be reduced without increasing the length. Further, since the timing for decreasing the voltage is determined depending on whether or not the gradation level is equal to or lower than the predetermined level, voltage switching control can be easily performed.

  In the second aspect of the present invention, the sublimation amount of the sublimable dye is changed by controlling the energization amount to each heating resistance element of the thermal head in which a plurality of heating resistance elements are arranged in a line, and according to the gradation level. In a sublimation type thermal printer for recording a recorded image on recording paper, energization means for energizing each heating resistor element for an energization time proportional to the gradation level of the pixel, a first voltage, and a second voltage lower than the first voltage And a voltage supply means for supplying any one of the first voltage and the second voltage output from the power supply circuit to the heating resistor element. When recording one line, the first voltage is supplied to the heating resistor element until the energization time exceeds a predetermined time, and the second voltage is applied to the heating resistor element after the energization time exceeds the predetermined time. Supply.

  Here, the energizing means corresponds to the CPU, control circuit, shift register, latch circuit, and driver circuit described in the embodiment.

  As described above, the energization amount (drive power) of the heating resistor element is reduced by lowering the voltage supplied to the heating resistor element when the energization time exceeds a predetermined time so as not to be affected by the thermal storage of the thermal head. Since it is lowered, the thermal storage of the thermal head is suppressed, and the occurrence of the tailing phenomenon due to the above-mentioned thermal storage can be prevented. Further, the problem of the tailing phenomenon is not solved by providing a pause time as in Patent Document 1, but the problem is solved by lowering the supply voltage to the heating resistor element. The power consumption can be reduced without increasing the length.

  In an embodiment of the second invention, the energizing means uses the data of each gradation level including a signal indicating that the pixel is above the gradation level and a signal indicating that the pixel is below the level. The heating resistor elements corresponding to the pixels of the gradation level or higher are energized for a predetermined time, and this energization is performed in order from the gradation level 1 to the maximum gradation level using the data of each gradation level.

  According to the present invention, the voltage supplied to the heating resistor element is reduced during the recording of one line, thereby eliminating the adverse effect of the thermal storage of the thermal head, thus preventing the occurrence of tailing without increasing the recording time. can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a mechanism of a sublimation thermal printer (hereinafter simply referred to as a printer), FIG. 2 is a diagram of the thermal head 6 shown in FIG. 1 viewed from below, and FIG. 3 is a block diagram showing the electrical configuration of the printer. FIG. 4 is a time chart showing the recording operation of the printer. In FIG. 1, 1 is a recording paper, 2 is a platen roller, 3 is an ink ribbon, 4 is a winding roll of the ink ribbon 3, 5 is a supply roll, and 6 is a thermal head. The recording paper 1 is made of a relatively thick postcard-size paper, and an image receiving layer is formed on the surface thereof. Also shown is the long side of the recording paper 1. The ink ribbon 3 is repeatedly coated with yellow, magenta, and cyan sublimation dyes in this order. The width of the ink ribbon 3 is equal to the width of the short side of the recording paper 1, and the length of each color region is equal to the long side of the recording paper 1 (more precisely, the recordable range L of the recording paper 1).

  As shown in FIG. 2, the thermal head 6 includes ten blocks 7, and 128 heating resistance elements R are arranged in a line on the surface of each block 7. Recording of the corresponding pixel is performed by each heating resistance element R. When the thermal ribbon 6 presses the ink ribbon 3 and the recording paper 1 against the platen roller 2 and energizes the heating resistance element R to heat the ink ribbon 3, the sublimated dye adheres to the recording paper 1 and the recording paper 1 is colored. Is done. In this case, the concentration of coloring increases as the energization time increases. Note that the conveyance mechanism for the recording paper 1 and the drive mechanism for the take-up roll 4 are not shown.

  The printer records an image on the recording paper 1 as follows. At the start of recording, the state is as shown in FIG. 1, and the recording head line A of the recording paper 1 and the head of the yellow area of the ink ribbon 3 are positioned directly below the thermal head 6. First, in this state, the recording head line A is colored yellow (a yellow image is recorded). When the recording of one line is completed, the recording paper 1 and the ink ribbon 3 are fed by one line in the direction of the arrow. This recording and feeding are repeated, and when the recording of the final recording line B is completed, the recording paper 1 is returned to the original position. At this time, the head of the magenta area of the ink ribbon 3 is located directly below the thermal head 6. Next, the magenta color is overprinted over the yellow color in the same manner as the yellow color. Further, thereafter, cyan coloring is overprinted on yellow and magenta coloring in the same manner. After the color image is recorded on the recording paper 1 in this way, the recording paper 1 is discharged from the printer.

  Next, recording control of the printer will be described with reference to FIGS. The CPU 11 performs control of each part of the printer, conversion of print data, various calculations, and the like according to a program stored in the ROM 13. The recording data transmitted from the personal computer and the recording data stored in the memory card are written into the first RAM 12 via the I / F circuit 14. This recording data is image data for each pixel represented by 8 bits (256 gradations) for each of R, G, and B. This recording data is converted into line data for each line and written to the second RAM 15. The line data is composed of data representing gradations of yellow, magenta and cyan, and is written in the second RAM 15 in this order.

  The control circuit 16 includes a timing signal generation circuit, a control signal generation circuit, and the like, and outputs a control signal (such as a shift clock or a strobe signal) based on a recording start signal from the CPU 11. Further, the line data read from the second RAM 15 is serialized at a predetermined timing, and the serialized gradation data is sent out in synchronization with the shift clock. The mechanism drive circuit 17 drives a mechanism such as the transport mechanism for the recording paper 1 described above. The power supply circuit 18 outputs 22V and 15V supplied to the heating resistor element R (R1 and the like) and 5V supplied to the CPU 11 and the like. One of 22V and 15V is selected by the switching circuit 19 and supplied to the heating resistor element R. This selection is performed by a switching signal from the control circuit 16.

  The gradation data is taken into the shift register 20 provided in the thermal head 6. The circuit in the thermal head 6 shown in FIG. 3 is a circuit of one block 7 out of the ten blocks 7 described above, and there are nine similar circuits not shown. As shown in FIG. 4, the gradation data for one line consists of 255 pieces of data (hereinafter referred to as gradation data). The data for each gradation is a bit string composed of 128 bits for each of the 128 heating resistance elements R. In each gradation data (1), a bit corresponding to a pixel having a gradation level of 1 or more is 1, and a bit corresponding to a pixel having a gradation level of 0 is 0. In the gradation data (255), the bit corresponding to the pixel having the gradation level of 255 is 1, and the bit corresponding to the pixel having the gradation level of 254 or less is 0. That is, in the data for each gradation (m), the bit corresponding to a pixel having a gradation level of m or higher is 1, and the bit corresponding to a pixel having a gradation level of less than m is 0.

  Immediately after the gray level data (1) is taken into the shift register 20 by the shift clock, the control circuit 16 outputs a latch signal, and the output signal of the shift register 20 is set in the latch circuit 21. Further, immediately after the latch signal, the control circuit 16 makes the strobe signal low, so that the output terminal of the driver circuit 22 whose non-inverting input terminal is high becomes low. As a result, a current supplied from the power supply circuit 18 flows through the heating resistor element R connected to the driver circuit 22, and the heating resistor element R is heated. Similarly, for each gradation data (2) to (255), the gradation data is taken into the shift register 20 and the latch circuit 21 is set at a constant period (hereinafter, this period is referred to as a latch period TL). Done. When the time TL elapses after the output of the latch signal for each gradation data (255), the control circuit 16 sets the strobe signal to high and the recording of one line is completed. Tc shown in FIG. 4 is a recording cycle for each line (recording time for one line).

  After the recording of one line is completed as described above, the gradation data (1) of the next line is taken into the shift register 20, and the recording of the next line is performed in the same manner. In addition, the recording paper 1 and the ink ribbon 3 are fed by one line before the latch signal of the gradation data (1) for the next line is output. From the above, the energization periods of the heating resistance elements R corresponding to the pixels of the gradation levels 255, 2, 1 are as shown in FIGS. 4 (e) to 4 (g), respectively. That is, the heating resistor element R is energized for a time proportional to the gradation level. Further, as described above, the thermal head 6 is divided into 10 blocks 7 and gradation data is transferred simultaneously from the control circuit 16 to the shift resist of each block 7. Transfer time can be shortened.

  Next, switching of the supply voltage of the heating resistor element R will be described. As the energization time of the heating resistor element R, that is, the heating time becomes longer, the temperature of the thermal head 6 rises, and the driving power of the heating resistor element R necessary for recording at a desired density decreases. Therefore, during the recording of one line, here, immediately after the latch signal of the gradation data (200), the supply voltage of the heating resistor element R is changed from 22V (first voltage) to 15V (second voltage) lower than the first voltage. Voltage). The operation of lowering the supply voltage is performed by the control circuit 16 sending a switching signal to the switching circuit 19 at the above timing. Further, since the control circuit 16 outputs a switching signal after the end of the recording cycle Tc and when the printer is turned on, the supply voltage thereafter becomes 22V. Note that the leading portion of the recording cycle Tc is the energization period of the heating resistor element R corresponding to the pixels of gradation levels 2 and 1 because the period when the supply voltage is 15 V is the energization period at a desired density. This is because the image is not colored.

  As described above, since the driving power of the heating resistor element R is reduced before the adverse effect due to the heat storage of the thermal head 6 occurs, the above-described tailing phenomenon can be prevented. Here, the drive voltage of the heating resistor element R is lowered from 22V (first voltage) to 15V (second voltage) immediately after the latch signal of gradation data (200). 6, the timing for switching from the first voltage to the second voltage and the optimum values of the first and second voltages are experimentally determined. Further, the switching of the supply voltage of the heating resistor element R does not necessarily have to be performed immediately after the latch signal, but may be in the middle of the latch cycle TL.

  In the embodiment described above, the recording paper 1 is described as being a relatively thick postcard-size paper, but the present invention can be implemented regardless of the size and thickness of the recording paper 1. In the above embodiment, the length of the recordable range L of the recording paper 1 is made equal to the length of each color area of the ink ribbon 3, and the recording paper 1 and the ink ribbon 3 are fed in the same amount. As has been conventionally performed, each color region can be half the recordable range L, and the feed amount of the ink ribbon 3 can be half the feed amount of the recording paper 1.

It is a figure which shows the mechanism of a sublimation type thermal printer. It is the figure which looked at the thermal head shown in FIG. 1 from the lower side. It is a block diagram which shows the electric constitution of a sublimation type thermal printer. It is a time chart which shows the recording operation of a sublimation type thermal printer. It is a block diagram which shows the structure of the conventional thermal head. It is a time chart which shows operation | movement of the conventional thermal head.

Explanation of symbols

1 Recording Paper 3 Ink Ribbon 6 Thermal Head 11 CPU
16 Control Circuit 18 Power Supply Circuit 19 Switching Circuit 20 Shift Register 21 Latch Circuit 22 Driver Circuit R, R1, R2, R128 Heating Resistance Element

Claims (3)

By controlling the energization amount to each heating resistance element of the thermal head in which a plurality of heating resistance elements are arranged in a line, the sublimation amount of the sublimation dye is changed and the image corresponding to the gradation level is recorded on the recording paper. In sublimation type thermal printer
Using the data of each gradation level consisting of a signal indicating that the pixel is above the gradation level and a signal indicating that the pixel is below the level, the heating resistor element corresponding to the pixel above the gradation level is set for a certain period of time. Energizing means for conducting the energization using the data of each gradation level in the order from gradation level 1 to the highest gradation level,
A power supply circuit that outputs a first voltage and a second voltage lower than the first voltage;
Voltage supply means for supplying either the first voltage or the second voltage output from the power supply circuit to the heating resistor element;
When recording one line, the first voltage is supplied to the heating resistor element during the period when the gradation level is lower than the predetermined level, and the second voltage is applied to the heating resistor element during the period when the gradation level is higher than the predetermined level. Sublimation type thermal printer characterized by supplying By controlling the energization amount to each heating resistance element of the thermal head in which a plurality of heating resistance elements are arranged in a line, the sublimation amount of the sublimation dye is changed and the image corresponding to the gradation level is recorded on the recording paper. In sublimation type thermal printer
Energization means for energizing each heating resistor element for energization time proportional to the gradation level of the pixel;
A power supply circuit that outputs a first voltage and a second voltage lower than the first voltage;
Voltage supply means for supplying either the first voltage or the second voltage output from the power supply circuit to the heating resistor element;
When recording one line, the first voltage is supplied to the heating resistor element until the energization time exceeds a predetermined time, and the second voltage is applied to the heating resistor element after the energization time exceeds the predetermined time. Sublimation type thermal printer characterized by supply. In the sublimation type thermal printer according to claim 2,
The energization means generates heat corresponding to a pixel having a gradation level or higher using data of each gradation level including a signal indicating that the pixel is higher than the gray level and a signal indicating that the pixel is lower than the gray level. A sublimation type thermal printer, wherein a resistance element is energized only for a predetermined time, and this energization is performed using data of each gradation level in order from gradation level 1 to the maximum gradation level.

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