JPH1029338A - Thermal transfer printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermal transfer printer in which print control is facilitated and printing is performed with uniform density by eliminating fluctuation in the print density regardless of fluctuation in the temperature distribution of an intermediate transfer body. SOLUTION: The thermal transfer printer comprises a thermal head 1 linearly arranged with a plurality of heat elements 2, an intermediate transfer roller 3 being driven by the thermal head 1 to retransfer ink from an ink ribbon onto a recording paper, and a preheat control means for controlling the preheating temperature by dividing the heat elements 2 in the thermal head 1 into a plurality of blocks 39 and controlling conduction of each heat element 2 in the thermal head 1 depending on the surface temperature distribution of the intermediate transfer roller 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer, and more particularly to a thermal transfer printer in which ink on an ink ribbon is melted by a thermal head and transferred once to an intermediate transfer member, and the ink is retransferred to a predetermined recording sheet. The present invention relates to an intermediate transfer-type thermal transfer printer that performs printing of an image.

[0002]

2. Description of the Related Art Heretofore, a heating resistor of a thermal head has been selectively heated based on a predetermined print signal, and the heat of the ink ribbon has been melted and transferred once to an intermediate transfer member. 2. Description of the Related Art An intermediate transfer type thermal transfer printer that performs desired printing by retransferring to predetermined recording paper is known.

FIG. 6 shows such a conventional intermediate transfer type thermal transfer printer, which is provided with a thermal head 1 as a line head driven based on predetermined print data. 1 has a plurality of heating resistors 2 arranged in a straight line. In the vicinity of the thermal head 1, an intermediate transfer roller 3 serving as an intermediate transfer body in which a surface of a cylindrical metal member is covered with a rubber material as an intermediate transfer body is rotatably disposed. A heater 4 for heating the intermediate transfer roller 3 is arranged inside the intermediate transfer roller 3. On both sides of the thermal head 1, a pair of ribbon rolls 6, 6 for guiding the ink ribbon 5 in a substantially linear manner between the intermediate transfer roller 3 and the thermal head 1 are provided. Is, for example, an ink ribbon 5 of four color inks of yellow, magenta, cyan, and black.
Are the color ink ribbons 5 sequentially and repeatedly formed in the longitudinal direction.

A drum 7, which is pressed against the intermediate transfer roller 3 with a strong pressing force at a position diametrically opposite to the thermal head 1 of the intermediate transfer roller 3, is rotated by driving a stepping motor (not shown). A heater 8 for heating the drum 7 is provided inside the drum 7, and a predetermined recording paper such as plain paper is provided on the surface of the drum 7. A clamper 10 for holding one end of the clamp 9 is provided.

In such a thermal transfer printer, assuming that the recording order is yellow, magenta, cyan, and black, first, by winding the ink ribbon 5, the leading position of the yellow ink ribbon 5 is Cueing is performed so as to be at a position opposite to the head 1. In this case, the color of the ink ribbon 5 is determined while recognizing a marker printed between the colors of the ink ribbon 5 by a photo sensor (not shown) or the like.

Next, the clamper 10 provided on the drum 7
While holding one end of the recording paper 9, the drum 7 is rotated to wind the recording paper 9 around the drum 7, a recording start position is specified by a sensor (not shown), and the rotation of the drum 7 is temporarily stopped. Stop.

In this state, the drum 7 is pressed against the intermediate transfer roller 3 with a strong pressing force, the thermal head 1 is pressed against the intermediate transfer roller 3, and the ink ribbon 5 is wound at a constant speed. While rotating the drum 3 and the drum 7, each heating resistor 2 of the thermal head 1 is selectively heated based on a predetermined print signal. The respective heating resistors 2 of the thermal head 1
, The yellow ink on the ink ribbon 5 is partially melted and transferred to the surface of the intermediate transfer roller 3. The ink transferred on the surface of the intermediate transfer roller 3 in this manner is re-transferred to the recording paper 9 conveyed by the rotating operation of the drum 7 by the pressing force of the drum 7.

When the yellow ink on the ink ribbon 5 has been retransferred to the recording paper 9, the pressure contact between the thermal head 1 and the drum 7 on the intermediate transfer roller 3 is released, and the ink ribbon 5 is conveyed idle. Of the head position of the magenta ink is performed. When the cueing of the magenta ink is completed, the transfer with the yellow ink,
Similarly to the retransfer operation, the intermediate transfer roller 3 and the thermal head 1 are brought into pressure contact with each other, and the intermediate transfer roller 3 and the drum 7 are brought into pressure contact with each other. To the recording paper 9 and retransfer to the recording paper 9 of the drum 7. By performing each of the above operations on the ink ribbon 5 of each color, a desired color print is obtained.

FIG. 7 shows another conventional thermal transfer printer of an intermediate transfer type. In this thermal transfer printer, an intermediate transfer belt 11 is used as an intermediate transfer member instead of an intermediate transfer roller. It is.

That is, a platen roller 12 against which the thermal head 1 is pressed and a pressure roller 13 against which the drum 7 is pressed with a constant pressing force are arranged in parallel and rotatably, respectively.
Between the intermediate transfer belt 11 and the pressure roller 13
With a constant tension.
The platen roller 12 to which the thermal head 1 is pressed and the pressure roller 1 to which the drum 7 is pressed
When the thermal head 1 transfers ink and the drum 7 transfers ink to the recording paper 9 separately, the conditions such as the set temperature can be set so as to be suitable for each function. You can do it.

In such a thermal transfer printer, similarly to the thermal transfer printer, after the ink ribbon 5 is caught, the recording paper 9 is sandwiched between the clampers 10 of the drum 7 and the recording paper 9 is transferred to the drum 7. Wrap around. In this state, the thermal head 1 is pressed against the platen roller 12 via the intermediate transfer belt 11 and the drum 7 is pressed against the pressure roller 13 via the intermediate transfer belt 11 to wind the ink ribbon 5 at a constant speed. At the same time, the heating resistors 2 of the thermal head 1 are selectively heated based on a predetermined print signal while rotating the intermediate transfer roller 3 and the drum 7. As a result, the ink on the ink ribbon 5 is transferred to the surface of the intermediate transfer belt 11 and the ink transferred on the surface of the intermediate transfer roller 3 is re-transferred to the recording paper 9 on the drum 7.
The desired color printing is performed.

FIG. 8 shows another conventional intermediate transfer type thermal transfer printer.
A pressure roller 13 is used instead of the drum 7 of the thermal transfer printer shown in FIG.
And the pressure roller 13. The other configuration is the same as that of the thermal transfer printer, and a description thereof will be omitted.

In this thermal transfer printer, similarly to the thermal transfer printer, the thermal head 1 and the pressure roller 13 are connected to the intermediate transfer roller 3 while the recording paper 9 is held between the intermediate transfer roller 3 and the pressure roller 13. 3, the ink ribbon 5 is wound at a constant speed, and while rotating the intermediate transfer roller 3 and the pressure roller 13, the thermal head 1 is driven to transfer the ink of the ink ribbon 5 to the surface of the intermediate transfer roller 3. At the same time, the ink transferred to the surface of the intermediate transfer roller 3 is re-transferred to the recording paper 9. When the printing of one color is completed, the recording paper 9 is reversely conveyed to the initial position, and printing with another color ink is performed.
By repeating this operation, desired color printing is performed.

FIG. 9 shows another conventional intermediate transfer type thermal transfer printer. This thermal transfer printer is replaced with an intermediate transfer roller 3 of the thermal transfer printer shown in FIG. 8 as shown in FIG. The intermediate transfer belt 11 is used.

The other configuration and operation are the same as those of the above-described thermal transfer printer, and the description thereof is omitted.

FIG. 10 shows a control circuit in the thermal transfer printer. The thermal transfer printer has a CPU 18 for controlling the thermal transfer printer. Between the CPU 18 and the thermal transfer printer, the drive of the thermal transfer printer is provided. A drive mechanism control circuit 20 for controlling the drive of a motor constituting the mechanism 19, a thermal head drive circuit 21 for generating a drive control signal for the thermal head 1 and controlling the energization and the like. Temperature detection circuit 22 for performing temperature detection for controlling the temperature to maintain the temperature.
Are connected respectively.

A host interface (I / F) circuit 23 for transferring print data from a host such as a personal computer to the CPU 18 is connected to the CPU 18. An environmental temperature detection circuit 24 for detecting the environmental temperature is connected.

FIG. 11 shows a detailed structure of the thermal head drive circuit 21. The thermal head drive circuit 21 performs a heat storage correction for performing an operation for controlling a power-on time in accordance with a power-on state. The heat storage correction circuit 25 receives print data S1 transferred from a data bus via a line memory 26 that stores print data for one line, and receives a line timing signal S2. And the basic clock supply circuit (O
SC) 27 to be input.

The thermal storage correction circuit 25 has a thermal effect on the future print line from the current print line, that is, the number of dots in one line for storing the thermal storage state of each heating resistor 2 of the thermal head 1, and a capacity of α. Are connected, and in the present embodiment, the heat storage value memories 28 are three heat storage value memories so as to be able to correct the thermal effects of three future print lines. 28. Further, the heat storage correction circuit 25
Is connected to an energization value memory 29 having a capacity of one line for storing the energization value (the number of energization times) obtained by the operation of the heat storage correction circuit 25. The energization value data S4 of the memory 29 is output, and at the time of preheating, all the energization value data are set to “H”.
(High) ”is connected.

The thermal head driving circuit 21
Has a head control signal generation circuit 31. The head control signal generation circuit 31 receives a line timing signal S2, a basic clock signal S3 output from the basic clock supply circuit 27, and a control signal S5 from the CPU 18. Each is to be entered. The head control signal generation circuit 31 starts operation in response to a line timing signal S2 to generate a drive signal for the thermal head 1. The head control signal generation circuit 31 synchronizes with the data transfer of print data. Then, a counter 32 for generating comparison value data S6 for comparison with the energization value data is connected.

Further, the OR circuit 30 has a data timing adjustment circuit 3 for adjusting the timing so that the energization value data S7 sequentially read out for each data transfer block of the thermal head 1 is output at the same timing.
3 is connected to the data timing adjusting circuit 3
3 includes a plurality of comparators 3 for comparing the energization value data S8 output from the data timing adjustment circuit 33 with the comparison value data S6 output from the counter 32.
4, 34... Are provided. Then, the print data S9 after the comparison is transferred from each of the comparators 34 to the thermal head 1. The number of the comparators 34 is the same as the number of data transfer blocks (the number of data inputs) to the thermal head 1. In this embodiment, since there are 20 data inputs, the number of the comparators 34 is 20. Have been.

FIG. 12 shows a detailed configuration of the thermal head 1 portion. The thermal head 1 has a heating resistor 2 formed by 2560 dots.
In the present embodiment, the heating resistor 2 is managed every 128 dots. The thermal head 1 is provided with 20 shift registers 35, 35... For serially inputting print data for each 128 dots outputted from the comparator 34. , A shift clock (SCLOCK) signal S10 from the head control signal generation circuit 31
Are input 128 times for each time section of t0, t1,.

Further, each of the shift registers 35 includes:
A latch circuit 36 for latching print data for 2560 dots based on a latch signal S11 from the head control signal generation circuit 31 in a state where the print data is shifted to all the shift registers 35 is connected. A driver 37 that drives each of the 2560-dot heating resistors 2 with the print data latched by the latch circuit 36 is connected to the latch circuit 36. The drive control of the driver 37 is performed by the strobe signal S12 from the head control signal generation circuit 31, and 2560 dots are simultaneously driven by one strobe signal.

Next, the printing operation of such a conventional thermal transfer printer will be described with reference to a timing chart shown in FIG.

Print data is transferred from a host such as a personal computer to the CPU 18 via the host interface circuit 23, and from the CPU 18 to the heat storage correction circuit 25 of the thermal head drive circuit 21 via the line memory 26 for one line of print data S 1. Is input, the heat storage correction circuit 25
Thus, based on the heat storage state of each heating resistor 2 of the thermal head 1 stored in the heat storage value memory 28, the energization value data (the number of times of energization) of each dot of the print line is calculated and stored in the energization value memory 29. . In this case, as shown in FIG.
The energizing period T of one line is set to 15 from t1 to t15.
For example, a dot having no heat storage is energized in a period of 15 from t1 to t15, and a dot in a heat storage state is energized in a period of 10 from t1 to t10. Then, a desired number of times of energization is calculated based on the heat storage state of each heating resistor 2 of the thermal head 1 stored in the heat storage value memory 28.

After the energization value data S4 is transferred to the OR circuit 30, the energization value data S7 is sent to the data timing adjustment circuit 33, and the data timing adjustment circuit 3
3, the energization value data S8 sequentially read out for each data transfer block of the thermal head 1 is output to the comparator 34 at the same timing. In this case, the energization value data is repeatedly read out at predetermined intervals by the number of divisions 15 in the energization period T of one line. On the other hand, the counter 32 outputs, to the comparator 34, comparison value data S6 for comparing with the energization value data in accordance with the drive signal from the head control signal generation circuit 31. The comparator 34 compares the energization value data S8 with the comparison value data S6. If the energization value data is greater than or equal to the comparison value data, an “H (high)” signal is obtained. ) "Signal is output to the shift register 35 as print data S9. This comparison value data is
During the period from t0 to t14, the count is sequentially increased from "1" at the transition of each energizing period. Therefore, for example, when the energization value data is 10, the "H" signal is output from the comparator 34 during the period t0 to t9, and the period t10 to t14.
, The "L" signal is output. In this dot, power is supplied during the period from t1 to t10, and t11 to t15
The period is de-energized. As a result, the total energization time of this dot is t × 10.

Then, all the shift registers 3 are controlled by the latch signal S11 from the head control signal generation circuit 31.
5 in a state where the print data has been shifted, the respective print data are latched by the latch circuit 36, and the driver 3 is controlled based on the strobe signal S12 from the head control signal generation circuit 31.
7, the respective heating resistors 2 are driven based on the print data latched by the latch circuit 36. In this case, the print data to be energized during the periods t1 to t15 are transferred during the period from t0 to t14. That is, the print data that is energized during the period t1 is transferred to the thermal head 1 during the period t0, and a latch signal is output and latched at the beginning of the period t1. The print data that is energized during the period t2 is the same as the thermal head 1 during the period t1.
And a latch signal is output at the beginning of the period of t2. At this time, the print data at t1 is replaced with the print data at t2, and the print data at t2 is latched. Similarly, by repeating the above operation, desired one-line printing is performed.

Next, a preheating operation of the conventional thermal transfer printer will be described with reference to a timing chart shown in FIG.

The preheating operation is for heating and keeping the temperature of the thermal head to a predetermined temperature during standby, and is performed by energizing the heating resistor 2 of the thermal head 1.

As shown in FIG. 14, the energizing cycle TCH in the preheating operation is the energizing cycle TC in the printing operation.
P, for example, the energizing cycle TCH at the time of the preheating operation is about two times the energizing cycle TCP at the time of printing.
It is doubled. This is to prevent the life of the heating resistor 2 from being affected.

When the preheating operation is performed, C
The control signal S5 of the “H” signal is sent from the PU 18 to the OR circuit 30.
As a result, the energization value data S7 output from the OR circuit 30 all become "H" signals, and the print data S9 output from the comparator 34 all become "H" signals. Therefore, during the preheating operation, the print data S1
a to S1v are forced to be "H" signals for all dots,
During the energizing period T, all the heating resistors 2 of 2560 dots generate heat.

[0032]

However, in the above-described conventional thermal transfer printer, the intermediate transfer member is affected by the environmental temperature, and the entire surface of the intermediate transfer member is made uniform by heat radiation of the intermediate transfer member. It is difficult to set the temperature, and a temperature difference occurs between the center and the end of the intermediate transfer member. As a result, since the surface temperature distribution of the intermediate transfer member is different, when printing is performed, the print density varies, and uniform printing cannot be performed.

Therefore, in the conventional thermal transfer printer, when performing a printing operation, the print data is controlled in accordance with the heat storage state of the heat generating resistor 2 of the thermal head 1 and the thermistor or the like disposed on the thermal head 1 Temperature detection circuit 2 based on the detection signal from the temperature detection means
2, the print data is controlled in accordance with the detected temperature. However, since both the control based on the heat storage state and the control based on the detected temperature are performed simultaneously, the print control is extremely difficult. There is a problem that it becomes complicated.

The present invention has been made in view of the above points, and can easily perform printing control. Even if the temperature distribution of the intermediate transfer member varies, the printing density unevenness is removed. It is an object of the present invention to provide a thermal transfer printer capable of performing uniform printing.

[0035]

According to a first aspect of the present invention, there is provided a thermal transfer printer including a thermal head in which a plurality of heating resistors are linearly arranged. An intermediate transfer member that is freely movable toward and away from the printer is disposed, and based on a desired print signal, the thermal head is driven to melt the ink of the ink ribbon and transfer the ink once to the intermediate transfer member. A thermal transfer printer that re-transfers to a predetermined recording sheet by heating and pressing, wherein each heating resistor of the thermal head is divided into a plurality of blocks, and each block corresponds to a surface temperature distribution of the intermediate transfer body. Preheating control means for controlling the preheating temperature by controlling the energization of each heating resistor of the thermal head.

According to the first aspect of the present invention, the preheating control means controls the energization of each heating resistor of the thermal head according to the surface temperature distribution of the intermediate transfer body for each block of the heating resistor. Since the preheating temperature is controlled, by performing this preheating, even if the surface temperature distribution of the intermediate transfer body varies,
It is possible to perform printing with uniform printing density by removing uneven printing density.

Further, the invention described in claim 2 is the same as that in claim 1
A temperature detecting means for detecting the temperature of the thermal head, wherein the preheating control means controls the energization control data determined for each block of the heating resistor in accordance with the temperature detected by the temperature detecting means. The preheating temperature is controlled by controlling the energization of each block of the heating resistor based on the above.

According to the second aspect of the present invention, the preheating control means controls the heat generation based on the energization control data determined for each block of the heating resistor in accordance with the temperature detected by the temperature detection means. Since the preheating temperature is controlled by controlling the energization of each block of the resistor, the preheating is performed according to the temperature of the thermal head. Even in this case, it is possible to perform printing with uniform print density by removing uneven print density.

Further, according to a third aspect of the present invention, in the second aspect, a preheating set in advance for each environmental temperature corresponding to each temperature distribution of the intermediate transfer member corresponding to each block of the heating resistor. An electric current value table is provided, and the preheating control means controls the preheating temperature based on the preheat electric value table.

According to the third aspect of the present invention, the preliminary heating energization value table is set for each environmental temperature corresponding to each temperature distribution of the intermediate transfer member with respect to each block set in advance, and is set based on the energization control data. Because the heating temperature is controlled, complicated control is not required during preheating, and even if the surface temperature distribution of the intermediate transfer body varies, it is possible to easily and properly adjust the print density unevenness. And printing with uniform print density can be performed.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an embodiment of a thermal transfer printer according to the present invention. The thermal transfer printer is a line head in which 2560 dots of heating resistors 2 driven based on predetermined print data are linearly arranged. In the vicinity of the thermal head 1, a cylindrical intermediate transfer roller 3 is rotatably arranged.

In the present embodiment, a thermistor 38 for detecting the temperature of the thermal head 1 is provided substantially at the center of the thermal head 1.
Further, in the present embodiment, the thermal head 1
Is divided into three blocks 39a, 39b, 39c of a first block 39a at one end, a second block 39b at the center, and a third block 39c at the other end, and printing is performed for each of these blocks 39a, 39b, 39c. The control is performed. These blocks 39a, 39b, 39c
Specifically, 2 of the heating resistor 2 of the thermal head 1
Of the 560 dots, the first block 39a is 1 to 640
Range of dots, 641 to 1920 in second block 39b
Dot range, third block 39c is 1921-256
It is set so as to fall within the range of 0 dots. Data is transferred to each of the heating resistors 2 by 20 data transfer blocks of 128 dots each. In the present embodiment, data 1 to 5 are stored in the first block 39a, Data 6 to 15 are stored in the block 39b.
However, the data 16 to 20 are respectively transferred to the third block 39c.

FIG. 2 shows a detailed structure of a thermal head drive circuit provided in a control circuit for controlling the drive of the thermal transfer printer. This thermal head drive circuit is stored in a heat storage value memory 28. A thermal storage correction circuit 25 for performing an operation for controlling the energization time based on the thermal storage state of each heating resistor 2 of the thermal head 1. The thermal storage correction circuit 25 includes one line of print data. The print data S1 transferred from the data bus via the line memory 26 for storing the line timing signal S2 and the basic clock supply circuit 2
7, the basic clock signal S3 output from each of them is input. In this case, as shown in FIG. 3, also in the present embodiment, the energization cycle TC of one line
The energizing period T for one line of P is set to t1 to t15.
5, the heat storage correction circuit 2
5, the desired number of times of energization is set so that energization is performed during a predetermined period from t1 to t15 according to the heat storage state of each heating resistor 2 of the thermal head 1 stored in the heat storage value memory 28. It is designed to calculate.

The heat storage correction circuit 25 has an energization value (the number of energization times) obtained by the operation of the heat storage correction circuit 25.
Is connected, and a selector 40 is connected to the current value memory 29. Further, in the present embodiment, there is provided a preheating energization value register 41 constituting preheating control means in which the energization value data S13 at the time of preheating sent via the data bus is set.

The surface temperature in the axial direction of the intermediate transfer roller 3 is low at both ends of the intermediate transfer roller 3 as shown in FIG. I will. For this reason, a preheating energization value table is set in advance so that the surface temperature distribution of the intermediate transfer roller 3 becomes a temperature distribution in which the print density during printing becomes constant. As shown in FIG. 4, the preheating energization value table 42 includes, for example, FIG.
0, three types of environmental temperatures are set as the environmental temperatures detected by the environmental temperature detection circuit 24 similar to that described in the above-described conventional example, and according to each of these environmental temperatures,
The energization value data is set for each of the blocks 39a, 39b, 39c. For example, in the present embodiment, the environment temperature A is set when the surface temperature at both ends of the intermediate transfer roller 3 is the highest, and the environmental temperature C is set when the surface temperature at both ends of the intermediate transfer roller 3 is the lowest.
For example, at any environmental temperature, the second block 3
The energization value data of 9b is set to 10, and the energization value data of the first and third blocks 39a and 39c are set to 13 at the environmental temperature A, 14 at the environmental temperature B, and 15 at the environmental temperature C. . The control circuit of the thermal transfer printer including the environmental temperature detecting circuit 24 of the present embodiment is the same as the control circuit of the thermal transfer printer shown in FIG.

Such a preheating energizing value table 42
Is stored in the ROM inside the CPU or in a ROM (not shown) connected to the CPU.
The preheating energization value data of the temperature corresponding to the environmental temperature detected by the above is read from the preheating energization value table 42 and set in the preheating energization value register 41 of the thermal head drive circuit via the data bus. I have.

The preheating energization value data S14 set in the preheating energization value register 41 is output to the selector 40.
0 indicates whether a printing operation is being performed by a control signal S5 including an “H” signal or an “L” signal output from the CPU,
It is configured to switch between the preheating operation and the data timing adjustment circuit 3 from the selector 40.
The output signal S15 to 3 is the energization value data from the energization value memory 29 during the printing operation and the preheating energization value data from the preheating energization value register 41 during the preheating. In this embodiment, the operation is switched to the preheating operation when the "H" signal is output from the CPU, and the operation is switched to the printing operation when the "L" signal is output.

The structure of the other parts is the same as that of the conventional one, and therefore the same parts are denoted by the same reference numerals and description thereof will be omitted.

Next, the operation of the present embodiment will be described with reference to the timing chart shown in FIG. 3 and the detailed configuration of the thermal head will be described with reference to FIG.

First, when performing the preheating operation in the present embodiment, the CPU outputs a switching signal S5 of the "H" signal of the preheating operation to the selector 40, and
By 0, switching is performed so as to output the preheating energization value data S14 from the preheating energization value register 41 to the data timing adjustment circuit 33. On the other hand, the ambient temperature is detected by the ambient temperature detecting circuit 24, and the preheating energizing value data of the temperature corresponding to the environmental temperature is read out from the preheating energizing value table 42 stored in the ROM. The data S13 is set in the preheating energization value register 41 of the thermal head drive circuit via the data bus.

The preheating current value register 41
Is supplied to the data timing adjustment circuit 33 via the selector 40, and the data timing adjustment circuit 33 reads the preliminary heating energization value data sequentially read out for each data transfer block of the thermal head 1. S8 is output to the comparator 34 at the same timing. In this case, the preheating energization value data is 1
The data is repeatedly read out at a predetermined interval by the number of divisions 15 of the line energization period T. On the other hand, by the counter 32,
Comparison value data S6 for comparison with preheating energization value data according to a drive signal from head control signal generation circuit 31
Is output to the comparator 34. The comparator 34 compares the preheating energization value data with the comparison value data. If the preheating energization value data is greater than or equal to the comparison value data, an “H” signal is output. If it is smaller, the "L" signal is used as the print data S9 in the shift register 35.
Is output to Therefore, for example, when the preheating energization value data is the preheating energization value data corresponding to the environmental temperature C, the first block 39a and the third block 39c
, The preheating energization value data is 15, and the "H" signal is output from the comparator 34 in all the periods t0 to t14. In the second block 39b, the preheating energization value data is 10 and Yes, period t0-t
In FIG. 9, the "H" signal is output from the comparator 34, and the "L" signal is output during the period t10 to t14. As a result, the dots in the first block 39a and the third block 39c are energized during the period from t1 to t15, the dots in the second block 39b are energized during the period from t1 to t10, and de-energized during the period from t11 to t15. Is done.

Then, according to the latch signal S11 from the head control signal generation circuit 31, all the shift registers 3
In a state where the print data (energization data) based on the preheating energization value data is shifted to 5, each print data is latched by the latch circuit 36, and the driver 37 operates based on the strobe signal S12 from the head control signal generation circuit 31. On the basis of the print data latched by the latch circuit 36, each heating resistor 2 is energized to perform predetermined preheating.

By performing such preheating control, the preheating temperature in the first block 39a and the third block 39c of the thermal head is controlled to be higher than the preheating temperature in the second block 39b. When printing is started from such a preheated state and the ink of the ink ribbon is transferred to the intermediate transfer roller 3 in which the surface temperature at both ends is low, the transfer temperature of the ink of the ink ribbon is apparently uniform. As a result, the printing density unevenness can be removed.

Next, when the printing operation is performed, the switching signal S5 of the "L" signal of the printing operation is sent from the CPU to the selector 40.
Is switched to output the energization value data S4 from the energization value register to the data timing adjustment circuit 33.

When one line of print data S1 is input from the CPU to the thermal storage correction circuit 25 of the thermal head driving circuit via the line memory 26, the print data S1 is stored in the thermal storage value memory 28 by the thermal storage correction circuit 25. Based on the heat storage state of each heating resistor 2 of the thermal head 1, the energization value data of each dot on the print line is calculated and stored in the energization value memory 29. This energization value data S4 is sent to the data timing adjustment circuit 33 as energization value data 15 via the selector 40, and the energization value data S8 output from the data timing adjustment circuit 33 and the counter 32
The comparison value data S6 output from the
And print data S9 as the print data S9.
5 is output.

Thereafter, all the shift registers 3 are controlled by the latch signal S11 from the head control signal generation circuit 31.
5 in a state where the print data has been shifted, the respective print data are latched by the latch circuit 36, and the driver 3 is controlled based on the strobe signal S12 from the head control signal generation circuit 31.
By driving each heating resistor 2 based on the print data latched by the latch circuit 36, a predetermined one-line printing is performed.

Therefore, in this embodiment, when performing the preheating operation, the preheating energization value data of the temperature corresponding to the environmental temperature detected by the environmental temperature detecting circuit 24 is read from the preheating energization value table 42. Then, the current is set in the preheating energization value register 41, and energization control of the heating resistor 2 of the thermal head 1 is performed based on the preheating energization value data. When transferring the ink on the ribbon, the transfer temperature can be made apparently uniform, and the printing density unevenness can be removed.
Unlike the related art, there is no need to perform preheating control based on the heat storage state of the heating resistor 2, so complicated control is not required, and printing with uniform print density can be easily and appropriately performed. it can.

FIG. 5 shows another embodiment of the present invention. In this embodiment, each of the blocks 39a, 39b, 39c of the thermal head 1 is provided at the central portion thereof. Blocks 39a, 39b, 39
thermistors 38a, 3 for detecting the temperature at
8b and 38c are respectively provided.

In the present embodiment, when performing preheating, the preheating temperature in each of the blocks 39a, 39b, 39c is set, and the thermistor 38 is set.
According to the temperatures detected by a, 38b, and 38c, preheating is performed until a predetermined preheating temperature is set.

By performing such control, as in the case of the above-described embodiment, it is possible to remove uneven printing density, and to easily and properly perform printing with uniform printing density. .

In the above-described embodiment, the heating resistor 2 of the thermal head 1 is divided into three blocks. However, the number of divisions may be set to any number. It is also possible to divide into 2560 every 2 and control the energization for each of these blocks.

The present invention is not limited to the above-described embodiment, and various changes can be made as needed.

[0064]

As described above, in the thermal transfer printer according to the first aspect of the present invention, each of the thermal heads is controlled by the preliminary heating control means in accordance with the surface temperature distribution of the intermediate transfer body for each block of the heating resistor. Since the preheating temperature is controlled by controlling the energization of the heating resistor, this preheating eliminates uneven printing density even if the surface temperature distribution of the intermediate transfer body varies. Thus, printing with uniform printing density can be performed.

Further, the invention according to claim 2 is characterized in that the preheating control means uses the power supply control data determined for each block of the heating resistor in accordance with the temperature detected by the temperature detection means. Since the preheating temperature is controlled by controlling the energization of each block of the heating resistor, the preheating according to the temperature of the thermal head causes variations in the surface temperature distribution of the intermediate transfer body. Even in such a case, printing with uniform printing density can be performed by removing uneven printing density.

Further, according to the present invention, the preheating temperature is controlled based on the energization control data which is set for each environmental temperature corresponding to each temperature distribution of each block set in advance in the preheating energization value table. So that
When performing preheating, complicated control is not required, and even if the surface temperature distribution of the intermediate transfer body varies, it is possible to easily and properly remove uneven print density to obtain uniform print density. It has the effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of a surface temperature distribution of a thermal transfer printer and an intermediate transfer member of the present invention.

FIG. 2 is a block diagram showing an embodiment of a thermal head driving circuit of the thermal transfer printer of the present invention.

FIG. 3 is a timing chart showing energization control during preheating in the thermal transfer printer of the present invention.

FIG. 4 is an explanatory diagram showing an embodiment of an energization value table in preheating energization control of the present invention.

FIG. 5 is a schematic explanatory view showing another embodiment of the surface temperature distribution of the thermal transfer printer and the intermediate transfer member of the present invention.

FIG. 6 is a schematic configuration diagram showing a conventional general intermediate transfer type thermal transfer printer.

FIG. 7 is a schematic configuration diagram showing another conventional intermediate transfer type thermal transfer printer.

FIG. 8 is a schematic configuration diagram showing another conventional intermediate transfer type thermal transfer printer.

FIG. 9 is a schematic configuration diagram showing another conventional intermediate transfer type thermal transfer printer.

FIG. 10 is a block diagram showing a control circuit of a thermal head in a conventional thermal transfer printer.

FIG. 11 is a block diagram showing a thermal head driving circuit of a conventional thermal transfer printer.

FIG. 12 is a schematic configuration diagram showing a configuration of a thermal head portion of a conventional thermal transfer printer.

FIG. 13 is a timing chart showing a power supply control during printing in a conventional thermal transfer printer.

FIG. 14 is a timing chart showing a power supply control at the time of preheating in a conventional thermal transfer printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal head 2 Heating resistor 3 Intermediate transfer roller 25 Heat storage correction circuit 29 Energization value memory 31 Head control signal generation circuit 32 Counter 33 Data timing adjustment circuit 34 Comparator 35 Shift register 36 Latch circuit 37 Driver 38 Thermistor 39 Block 40 Selector 41 Reserve Heating current value register 42 Preheating current value table

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshihiko Hatakeyama 1-7 Yukitani Otsukacho, Ota-ku, Tokyo Alps Electric Co., Ltd. (72) Inventor Isao Owada 1-7 Yukitani Otsukacho, Ota-ku, Tokyo Alp SU Electric Co., Ltd.

Claims (3)

[Claims] 1. A thermal head in which a plurality of heating resistors are linearly arranged, an intermediate transfer member which can be freely moved toward and away from the thermal head is provided, and a thermal head is provided based on a desired print signal. A thermal transfer printer that drives the thermal head to melt the ink of the ink ribbon, transfers the ink once to an intermediate transfer body, and heats and pressurizes the ink to retransfer it to a predetermined recording sheet. Each heating resistor is divided into a plurality of blocks, and for each of these blocks, the current supply to each heating resistor of the thermal head is controlled according to the surface temperature distribution of the intermediate transfer member, thereby controlling the preliminary heating temperature. A thermal transfer printer comprising a heating control means. 2. A temperature detecting means for detecting a temperature of the thermal head, wherein the temperature is determined for each block of the heating resistor by the preheating control means in accordance with the temperature detected by the temperature detecting means. 2. The thermal transfer printer according to claim 1, wherein a preheating temperature is controlled by performing a power supply control on each block of the heating resistor based on the power supply control data. 3. A preheating energization value table set in advance for each environmental temperature corresponding to each temperature distribution of the intermediate transfer member with respect to each block of the heating resistor is provided. 3. The thermal transfer printer according to claim 2, wherein the preheating temperature is controlled based on a current value table.