JPH0725053A - Thermal transfer recording device - Google Patents

Abstract

PURPOSE:To prevent recording images from becoming faint in recording the images under low temperature when temperature of a thermal head is not sufficiently high at start of image recording. CONSTITUTION:A temperature detecting means 17 for detecting temperature of a thermal head and a thermionic cooling element 18 for controlling the temperature of the thermal head controlled by the temperature detected by the temperature detecting means 17 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording apparatus using a thermal head.

[0002]

2. Description of the Related Art A thermal transfer recording apparatus for heating an ink sheet having an ink layer by a thermal head for generating a heat pattern according to image recording information and recording the image information on the image receiving paper from the ink sheet, or an image recording information In a thermal transfer recording device that directly heats image-receiving paper (thermal paper) by a thermal head that generates a corresponding heat pattern to record image information on the image-receiving paper, when recording image information on the image-receiving paper, use the thermal head Electric pulses are selectively applied to a large number of heating resistors provided in accordance with image recording information such as print data. This electric pulse causes the heating resistor to selectively generate heat, and the ink layer of the ink sheet or the image receiving paper is heated at that temperature, and image recording information is recorded on the image receiving paper.

Japanese Unexamined Patent Publication No. 59-202881 discloses a printer device of a thermal transfer type or a thermal type,
It is described that the shaft of the pressure roller is hollow and a refrigerant is circulated in the hollow portion to cool the pressure roller to prevent the ink from overheating. Further, in Japanese Unexamined Patent Publication No. 61-173975, the temperature of the base of the thermal recording head is detected by a thermal element, and the rotation of the fan motor is controlled according to the detection result to cool the thermal recording head in plural. A thermal recording device is described which is controlled in steps or continuously.

Further, Japanese Patent Laid-Open No. 61-217274 discloses a thermal head driving device. In this thermal head drive device, the thermal head is continuously cooled during the recording operation of the thermal head, and further, even if the thermal head finishes the recording operation, the substrate is cooled until the substrate temperature becomes equal to or lower than a predetermined temperature. continue. In addition, the temperature of each part of the substrate is measured and the temperature distribution is predicted, and depending on the result, the substrate is cooled with independent cooling power for each predetermined section even during or after the recording operation of the thermal head. By doing so, when local heat accumulation occurs in the substrate, that part is intensively cooled to make the temperature of the entire substrate uniform.

[0005]

In the above thermal transfer recording apparatus, a plurality of heat generating resistors provided in the thermal head are selectively applied with electric pulses according to image recording information such as print data to generate heat generating resistors. To selectively generate heat,
If the temperature of the heating resistor is not sufficiently high, the recording of image recording information will be insufficient and the recorded image on the image receiving paper will be faint. Also, if the temperature of the heating resistor is too high, the image recording information will be recorded on the image receiving paper in darker than necessary, the recording area will be wide and the details of the recorded image will be crushed, the recorded content will be blurred, and the trailing etc. Phenomenon occurs and the quality of the recorded image deteriorates. Further, even if good image recording is performed at the start of recording, density unevenness occurs in the recorded image due to the heat accumulation phenomenon of the entire thermal head in the first half and the second half of the long-time recording work.

In order to eliminate such a phenomenon, in the printer disclosed in the above-mentioned Japanese Patent Laid-Open No. 59-202881, the shaft of the pressure roller is hollow in the printer device of the thermal transfer system or the thermal system and the refrigerant is contained in the hollow portion. The ink is prevented from being overheated by circulating the pressure roller to cool the pressure roller, and the excessive heat storage of the thermal head is prevented even if the ink is continuously used for a long time. However, when the apparatus becomes large and the temperature of the thermal head at the time of image recording in a low temperature environment or at the start of image recording is not sufficiently high, ink transfer etc. becomes insufficient and the recorded image becomes faint. That problem cannot be solved.

Further, in the one disclosed in Japanese Patent Laid-Open No. 61-173975, the temperature of the base of the thermal recording head is detected by a thermal element, and the rotation of the fan motor is controlled in accordance with the detection result to perform thermal recording. The cooling of the head is controlled in multiple steps or continuously, but this is also the case when the temperature of the thermal head at the time of image recording in the low temperature environment or when the image recording is started is not sufficiently high. However, it is impossible to solve the problem that the recorded image becomes faint due to insufficient conditions.

Further, in the one disclosed in Japanese Patent Laid-Open No. 61-217274, the thermal head is continuously cooled during the recording operation of the thermal head, and further, even if the thermal head finishes the recording operation, the substrate temperature is not changed. Continue cooling the substrate until the temperature falls below a predetermined temperature, measure the temperature of each part of the substrate and predict the temperature distribution, and depending on the result, during or after the recording operation of the thermal head, When local heat accumulation occurs in the substrate by cooling the substrate with independent cooling power for each predetermined section, that part is intensively cooled to make the temperature of the entire substrate uniform. Similarly, when recording an image in a low temperature environment or when the temperature of the thermal head at the start of image recording is not sufficiently high, the transfer of ink is insufficient and the recorded image becomes faint. It can not be eliminated.

The present invention solves the above-mentioned drawbacks and solves the problem that the recorded image is faint when the image is recorded in a low temperature environment or when the temperature of the thermal head at the start of image recording is not sufficiently high. An object of the present invention is to provide a thermal transfer recording device capable of performing the above.

[0010]

In order to achieve the above object, the invention according to claim 1 heats an ink sheet having an ink layer by a thermal head which generates a heat pattern according to image recording information. In a thermal transfer recording apparatus that records image information from a sheet on an image receiving sheet or directly heats the image receiving sheet by a thermal head that generates a heat pattern according to the image recorded information to record the image information on the image receiving sheet, The temperature detecting means for detecting the temperature of the head and the thermoelectric cooling element controlled by the temperature detected by the temperature detecting means to control the temperature of the thermal head are provided.

According to a second aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, a plurality of thermoelectric cooling elements and a plurality of temperature detection elements facing each other as the temperature detecting means and the thermoelectric cooling elements are provided. Means are provided, and the plurality of thermoelectric cooling elements are independently controlled by the temperatures detected by the plurality of temperature detecting means.

According to a third aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, a Peltier element is used as the thermoelectric cooling element.

According to a fourth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the electric power to the thermoelectric cooling element is controlled so as to keep the temperature of the thermal head within a predetermined range. Is.

According to a fifth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the temperature detecting means includes a plurality of temperature detecting means for detecting temperatures at a plurality of positions of the thermal head. If at least one of the temperatures detected by the detection means is within a predetermined temperature range, the thermoelectric cooling element heats the thermal head, and conversely, at least one of the temperatures detected by the plurality of temperature detection means is predetermined. When the temperature is above the temperature range, the thermionic cooling element cools the thermal head.

According to a sixth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the heat emission side of the thermoelectric cooling element is attached to a frame of the thermal transfer recording apparatus.

According to a seventh aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, a substance having a high thermal conductivity is interposed between the heat absorbing side of the thermoelectric cooling element and the thermal head. .

[0017]

According to the first aspect of the invention, the temperature of the thermal head is detected by the temperature detecting means, and the thermoelectric cooling element is controlled by the temperature detected by the temperature detecting means to control the temperature of the thermal head. Quality deterioration can be prevented.

According to a second aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, a plurality of thermoelectric cooling elements and a plurality of temperature detecting means face each other in each section, and the plurality of temperature detecting means detect the temperature. By controlling a plurality of thermoelectric cooling elements independently of each other according to the temperature, the temperature of the entire thermal head can be made uniform.

According to a third aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the Peltier element is used as the thermoelectric cooling element, so that the temperature of the thermal head can be easily controlled.

According to a fourth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the power consumption is controlled by controlling the electric power to the thermoelectric cooling element so that the temperature of the thermal head is maintained within a predetermined range. Can be reduced and a stable image can be obtained.

According to a fifth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, temperatures at a plurality of locations of the thermal head are detected by a plurality of temperature detecting means, and the temperature detected by the plurality of temperature detecting means is detected. If even one is within the predetermined temperature range, the thermoelectric cooling element heats the thermal head. On the contrary, if even one of the temperatures detected by the plurality of temperature detecting means is above the predetermined temperature range, the thermoelectron cooling element cools the thermal head, so that the temperature variation in the thermal head can be prevented.

According to a sixth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the thermal emission side of the thermoelectric cooling element is attached to the frame of the thermal transfer recording apparatus, so that the thermal head is heated or cooled. You can increase efficiency.

According to a seventh aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, a substance having a high thermal conductivity is interposed between the thermal absorption side of the thermoelectric cooling element and the thermal head. The temperature can be controlled efficiently and evenly, and variations in temperature of the thermal head can be reduced.

[0024]

FIG. 2 shows the outline of the first embodiment of the present invention. The thermal transfer recording apparatus of the first embodiment includes a thermal head 11,
It has a recording paper 12 serving as an image receiving paper, an ink sheet 13, and a platen roller 14, and the recording paper 12 and the ink sheet 13 are held between the thermal head 11 and the platen roller 14. The recording paper 12 is conveyed by the capstan roller 15 and the pinch roller 16, and the ink sheet 13 is the recording paper 1.
It is transported at the same time as 2. A large number of heat-generating resistors of the thermal head 11 are selectively heated according to image recording information by applying an electric signal (pulse signal) to flow a current to selectively heat the ink sheet 13 to form an ink layer. The ink sheet 13 included therein is heated by a heating resistor to transfer the ink onto the recording paper 12 to perform image recording.

A temperature detecting element, for example, a thermistor 17, is attached to the thermal head 11, and the thermal head 11
Temperature (base temperature of the thermal head 11) is the thermistor 1
Detected by 7. A thermoelectric cooling element 18 is attached to the thermal head 11, and the thermoelectric cooling element 1
A heat radiating plate 19 is attached to the surface of 8 opposite to the thermal head 11. The fan 20 blows air onto the heat dissipation plate 19 in order to enhance the heat dissipation effect.

FIG. 1 shows a thermal head temperature control section in the first embodiment. The resistance value of the thermistor 17 changes according to the temperature of the thermal head 11, and the temperature detection circuit 21 converts the resistance value of the thermistor 17 into temperature information and outputs it to the controller 22. The controller 22 determines whether the temperature of the thermal head 11 is higher or lower than the set temperature based on the input signal from the temperature detection circuit 21, and outputs the determination result to the power control circuit 23.

The power control circuit 23 has a heating power control circuit and a cooling power control circuit, and when the temperature of the thermal head 11 is lower than the set temperature by the input signal from the controller 22, a thermoelectric cooling element, for example, A current is supplied to the Peltier element 18 by a heating power control circuit so that the surface of the Peltier element 18 on the thermal head 11 side is heated. On the contrary, when the temperature of the thermal head 11 is higher than the set temperature, the power control circuit 23 supplies a current to the Peltier element 18 by the cooling power control circuit so that the surface of the Peltier element 18 on the thermal head 11 side is cooled. .

FIG. 3 shows a temperature control flow of the controller 22. When the power supply is turned on, the controller 22 takes in an input signal from the temperature detection circuit 21, and whether the temperature t of the thermal head 11 detected by the thermistor 17 is lower than the set temperature a based on the input signal from the temperature detection circuit 21. Determine whether When the temperature t of the thermal head 11 is lower than the set temperature a, the controller 22 turns on the heating power control circuit in the power control circuit 23, and the Peltier element 18 is turned on by the heating power control circuit to turn on the thermal head. Heat 11.

When the temperature t of the thermal head 11 is equal to or higher than the set temperature a, the controller 22 turns on the cooling power control circuit in the power control circuit 23, and the Peltier element 18 is turned on by the cooling power control circuit. Then, the thermal head 11 is cooled. By repeating such an operation, the temperature of the thermal head 11 is maintained at the set temperature.

FIG. 4 shows the temperature change of the thermal head in the thermal transfer recording apparatus. In FIG. 4, the solid line indicates the thermal head 1 in the first embodiment using the Peltier element 18.
1 shows the temperature change, the dotted line shows the temperature change of the thermal head when there is no means for cooling and heating the thermal head, and the broken line shows the temperature change of the thermal head when the thermal head is cooled by a fan.

As can be seen from FIG. 4, while waiting for printing (image recording) after the power is turned on, there are no means for cooling and heating the thermal head and a case where the thermal head is cooled by a fan. The temperature of the head becomes almost the same as the ambient temperature. On the other hand, in the first embodiment, the temperature of the thermal head rises to the set temperature a due to the heating by the Peltier element 18 at the same time when the power is turned on.

When printing is started, if there is no means for cooling and heating the thermal head, the temperature of the thermal head rises at once and heat is accumulated in the thermal head, and if the temperature of the thermal head rises too much. The thermal head will be damaged. When the thermal head is cooled by a fan, the temperature of the thermal head can be maintained at the set temperature a during printing if the cooling capacity of the fan is sufficient and the air volume of the fan can be controlled.

When printing is completed, when the thermal head is cooled by a fan, the temperature of the thermal head gradually drops to the ambient temperature. However, when the thermal head is cooled by a fan, there is no problem during printing, but since the temperature of the thermal head is low immediately after the start of printing, a blurred image or the like occurs. In the first embodiment, the temperature of the thermal head 11 is set to the set temperature a at the start of printing, and immediately after the start of printing, the thermal head 11 is cooled by the Peltier element 18 as the temperature of the thermal head 11 rises.
Can be maintained at the set temperature a. In this case, the temperature of the thermal head 11 is slightly increased, but the cooling capacity of the Peltier element 18 is increased,
It is possible to accurately control the temperature of the thermal head 11 to the set temperature a by using a plurality of.

The set temperature a will be described below.
As is clear from the relationship between the ink heating temperature and the ink density shown in FIG. 12, the ink of the ink sheet 13 is transferred onto the recording paper 12 only at a certain temperature or higher, so the set temperature a is the value shown in FIG. If the temperature is set to 1, the ink of the ink sheet 13 will not be transferred to the recording paper 12 if the base temperature of the thermal head 11 is the set temperature a, and after applying an electric signal to the heating resistor of the thermal head 11. The rising time until the ink of the ink sheet 13 is transferred to the recording paper 12 due to the heat generation of the heat generating resistor is faster than that of the conventional apparatus, and the image is not blurred at the start of printing.

In the first embodiment, a Peltier element is used as the thermoelectric cooling element 18, but the Peltier element keeps the entire circuit at a constant temperature and when a current is passed through the junction, heat is generated or absorbed at the junction. Done. By utilizing the effect of this Peltier element, the object can be cooled by an endothermic reaction. Therefore, when a current is passed from the power control circuit 23 to the Peltier element 18, heat is absorbed from the surface of the Peltier element 18 in contact with the thermal head 11, and the heat of the thermal head 11 is absorbed by the Peltier element 18 one after another. .

The heat absorbed by the Peltier element 18 is transferred to the other side from the surface of the Peltier element 18 opposite to the thermal head 11, and is radiated to the outside by the heat radiating plate 19 in the first embodiment. Further, by changing the direction of the current of the Peltier element, it is possible to reverse the direction of heat absorption and release by the Peltier element. Therefore, the controller 22
By controlling the direction of the current of the Peltier element 18 via the power control circuit 23, the Peltier element 18 of the thermal head 11 heats and cools. In addition, in order to improve the efficiency of cooling and heating of the thermal head 11, a portion where cooling and heating of the thermal head 11 are performed, in this case, between the thermal head 11 and the heat dissipation plate (heat absorbing plate) 19 (excluding the Peltier element 18). A heat insulating material may be provided in the portion).

As described above, in the first embodiment, the temperature of the thermal head 11 is detected, and the Peltier element 18 is controlled by the detected temperature to constantly control the temperature of the thermal head 11. Therefore, image recording in a low temperature environment is performed. It is possible to solve the problem that the thermal head is heated when the temperature of the thermal head is not high enough at the start of image recording or when the image is recorded, and the recorded image is blurred. When the heat storage phenomenon occurs, the thermal head can be cooled, and deterioration of the printed image quality can be prevented. Further, by using a plurality of thermionic cooling elements 18, it is possible to increase the speed and efficiency of heating and cooling of the thermal head, and further it is possible to prevent temperature variations in the thermal head. Further, by using a Peltier element as the thermoelectric cooling element 18 and controlling the current thereof, the temperature of the thermal head can be easily controlled.

FIG. 5 shows a part of the second embodiment of the present invention.
In the second embodiment, as in the first embodiment, the temperature detecting elements 17 _{1 to} 17 _{3 are} composed of a plurality of sets, for example, three sets of thermistors as the temperature detecting elements 17 and the thermoelectric cooling elements 18.
And thermoelectric cooling elements 18 ₁ to 18 _{3 including} Peltier elements
Are arranged to face each other, and the temperature detecting elements 17 ₁ to 1
Numeral 7 ₃ detects the respective temperatures of the central portion and both end portions of the thermal head 11 in the line direction (width direction of the recording paper 12). As shown in FIG. 6, in the case where an image is recorded only on the central portion 12a of the recording paper 12, if there is no means for cooling and heating the thermal head, the temperature-temperature distribution of the thermal head 11 is shown by the solid line in FIG. Thus, the temperature of the central portion of the thermal head 11 becomes high.

Further, depending on the temperature of the central portion of the thermal head 11 detected by the thermistor 17 ₂ , the Peltier element 18
_{When 1} to 18 ₃ are controlled, the temperature at the center of the thermal head 11 becomes the set temperature a as shown by the broken line in FIG. 6, but the temperature at both ends of the thermal head 11 becomes low.
In the second embodiment, the output signals of the temperature detecting element 17 _{1-17 3} is inputted to the controller 22 via the temperature detection circuit, respectively, the controller 22 via respective power control circuit by the output signal of the temperature detection circuit The thermoelectric cooling elements 18 ₁ to 18 ₃ are controlled by the temperature control flow shown in FIG.
For this reason, the temperature distribution of the thermal head 11 is kept substantially at the set temperature a as shown by the dotted line in FIG.

As described above, in the second embodiment, as the temperature detecting element 17 and the thermoelectric cooling element 18, a plurality of sets of temperature detecting elements 17 _{1 to} 17 ₃ and thermoelectric cooling elements 18 ₁ to 18 ₃ are arranged facing each other. However, since the thermoelectric cooling elements 18 ₁ to 18 ₃ are controlled independently by the temperature detected by the temperature detecting elements 17 _{1 to} 17 ₃ for each section, if local heat accumulation occurs in the thermal head, that portion Can be intensively cooled to make the temperature of the entire thermal head uniform.

FIG. 7 shows a temperature control flow of the controller in the third embodiment of the present invention. In this third embodiment,
In the first embodiment, the controller 22 executes the temperature control flow shown in FIG.
The values a, b, and c satisfying <c <b are set. Controller 2
When the power source is turned on, 2 receives the input signal from the temperature detection circuit 21, and the thermal head 11 detected by the thermistor 17 by the input signal from the temperature detection circuit 21.
It is determined whether the temperature t of is lower than the set temperature c. Then, if t <c, the controller 22 turns on the heating power control circuit in the power control circuit 23, and the Peltier element 18 is turned on by the heating power control circuit to heat the thermal head 11.

If the temperature t of the thermal head 11 becomes equal to or higher than the set temperature c by repeating such processing, the controller 22 and the power control circuit 23 and the Peltier element 1
8 is turned off and then the input signal from the temperature detection circuit 21 is taken in to keep the temperature t of the thermal head 11 at a predetermined temperature a.
If the temperature t of the thermal head 11 is lower than the predetermined temperature a, the process returns to the step of turning on the heating power control circuit in the power control circuit 23.

If the temperature t of the thermal head 11 is not higher than the predetermined temperature a, the controller 22 determines whether the temperature t of the thermal head 11 is higher than the predetermined temperature b, and the temperature t of the thermal head 11 is predetermined. If the temperature is equal to or lower than the temperature b, the process returns to the step of turning off the power control circuit 23 and the Peltier device 18.

When the temperature t of the thermal head 11 becomes higher than a predetermined temperature b, the controller 22 turns on the cooling power control circuit and the Peltier element 18 in the power control circuit 23 to input the input signal from the temperature detection circuit 21. Is read to determine whether the temperature t of the thermal head 11 is higher than a predetermined temperature c, and the temperature t of the thermal head 11 is
Is higher than the predetermined temperature c, the process returns to the step of turning on the cooling power control circuit in the power control circuit 23.
Further, the controller 22 controls the temperature t of the thermal head 11.
Is below the predetermined temperature c, the process returns to the step of turning off the power control circuit 23 and the Peltier device 18.

In the third embodiment, the electric power to the thermoelectric cooling element is controlled so as to keep the temperature of the thermal head within a predetermined range. Therefore, the electric power consumed by the thermoelectric cooling element is reduced and a stable image is displayed. Obtainable.

Also in the third embodiment, as in the second embodiment, as the temperature detecting element 17 and the thermoelectric cooling element 18, a plurality of thermistor temperature detecting elements 17 ₁ to 17 _{1 are used.}
7 ₃ and thermoelectric cooling elements 18 ₁ to ₁ composed of Peltier elements
8 ₃ are arranged so as to face each other, and the temperature detecting elements 17 ₁ ...
17 ₃ each to respectively detect the temperature of the plurality of locations in the line direction of the thermal head 11 by the temperature detecting element 17 _{1-17 3}
Of the thermoelectric cooling elements 18 ₁ to 18 ₃ shown in FIG. 7 via the electric power control circuit. You may make it control by a control flow.

8 and 9 show the temperature control flow of the controller in the fourth embodiment of the present invention. In the fourth embodiment, the controller 22 executes the temperature control flow shown in FIG. 8 in the first embodiment, and a, b, and c satisfying a <c <b are set. As the temperature detecting element 17, temperature detecting elements 17 ₁ and 17 ₂ (not shown) composed of two thermistors are provided, and the temperature at two points of the thermal head 11 is two thermistors 17 ₁ and 17 _2.
Respectively detected by.

When the controller 22 is turned on,
The output signals of the _two thermistors 17 ₁ and 17 ₂ are taken in via a temperature detection circuit, and _one of the detected temperatures t ₁ and t ₂ of the thermistors 17 ₁ and 17 ₂ is detected by the input signal from this temperature detection circuit. It is determined whether the temperature t ₁ is lower than the set temperature c. When the detected temperature t ₁ is lower than the set temperature c, the controller 22 turns on the heating power control circuit in the power control circuit 23, and the Peltier element 1
8 is turned on by the heating power control circuit to heat the thermal head 11.

Further, the controller 22 detects the detected temperature t ₁
If the detected temperature t ₂ is lower than the set temperature c, it is determined whether the other detected temperature t ₂ is lower than the set temperature c. If the detected temperature t ₂ is lower than the set temperature c, the process returns to the step of turning on the heating power control circuit. . If the detected temperature t ₂ is equal to or higher than the set temperature c, the controller 22 turns off the power control circuit 23 to turn off the Peltier element 18, and the thermistor 1
7 _1, 17 thermistor 17 ₁ by an input signal from the temperature detection circuit takes in through the temperature detection circuit output signal of the _2, 17 ₂ of the detected temperature t _1, t ₂ determines whether less than a .

The controller 22 returns to the step of turning on the heating power control circuit when the detected temperature t ₁ or t ₂ is lower than a, and when the detected temperatures t ₁ and t ₂ are both a or higher. It is determined whether the detected temperatures t ₁ and t ₂ are higher than b. Then, the controller 22 returns to the step of turning off the power control circuit 23 when the detected temperatures t ₁ and t ₂ are both b or less.

The controller 22 also detects the detected temperature t ₁
Alternatively, when t ₂ is higher than b, the cooling power control circuit in the power control circuit 23 is turned on, and the Peltier element 18
Is turned on by the cooling power control circuit and the thermal head 1
Cool 1. Next, the controller 22 takes in the output signals of the thermistors 17 ₁ and 17 ₂ via the temperature detection circuit, and detects the temperatures t ₁ and t ₂ detected by the thermistors 17 ₁ and 17 ₂ by the input signal from the temperature detection circuit. Judge whether it is higher than c.

The controller 22 returns to the step of turning on the cooling power control circuit when the detected temperature t ₁ or t ₂ is higher than c, and when the detected temperatures t ₁ and t ₂ are both c or less. The process returns to the step of turning off the power control circuit 23. By repeating such an operation, the temperature of the thermal head 11 is maintained within a predetermined range.

In the fourth embodiment, the thermal head 11 is heated if at least one of the detected temperatures t ₁ and t ₂ of the plurality of temperature detecting elements 17 ₁ and 17 ₂ is below the predetermined temperature range c, On the contrary, if even one of the detected temperatures t ₁ and t ₂ exceeds the predetermined temperature range c, the thermal head 11 is cooled.
It is possible to eliminate locally low temperature parts and high temperature parts of the thermal head, and prevent temperature variations in the thermal head. Although the two temperature detecting elements 17 ₁ and 17 ₂ are used as the temperature detecting elements, three or more temperature detecting elements may be used, and the number of temperature detecting elements should be as large as possible.

FIG. 10 shows the outline of the fifth embodiment of the present invention. In the fifth embodiment, the roll recording paper is used instead of the recording paper 12 and the ink sheet 13 in the first embodiment.
(Thermal paper) 24 is used as the image receiving paper, and the recording paper 24
Is held between the thermal head 11 and the platen roller 14 and conveyed by the capstan roller 25 and the pinch roller 26. The thermal head 11 generates a heat pattern according to the image recording information by selectively applying an electric signal (pulse signal) to a large number of heating resistors to generate heat, and the recording paper 24 is heated by the thermal head 11 and the platen roller 14. The image information is recorded by being heated by the heat generated by the heat-generating resistor in the thermal head 11 when the image information is passed between and.

Since the thermal head 11 does not have to move up and down, it is fixed to the frame (cover) 27 of the thermal transfer recording apparatus via the thermoelectric cooling element 18 and the heat dissipation plate 19. The frame 27 has a high thermal conductivity,
By using the frame 27 as a heat radiating plate and a heat absorbing plate, the area of the heat radiating plate and the heat absorbing plate is increased, and the efficiency of heat radiation and heat absorption is improved. The thermoelectric cooling element 18 may be directly attached to the frame 27, or in some cases, a fan may be used to cool the frame 27 and the radiator plate 19.

In the fifth embodiment, the thermoelectric cooling element 18
Since the heat radiating side (the heat absorbing side when the temperature of the thermal head 11 is raised) is attached to the frame 27 of the thermal transfer recording apparatus, it is possible to increase the area of the heat radiating and heat absorbing section without changing the size of the apparatus. Therefore, the efficiency of heating or cooling the thermal head 11 can be improved. In the thermal transfer recording apparatus in which the thermal head 11 moves up and down as in the first embodiment, the thermal head 11 cannot be completely fixed, but the heat dissipation plate and the fan are used to dissipate the heat from the thermoelectric cooling element 18. Absorbs heat, and
If the frame of the thermal transfer recording apparatus and the thermionic cooling element are connected by a leaf spring or the like, the efficiency of heat dissipation and heat absorption will be further improved.

FIG. 11 shows a part of the sixth embodiment of the present invention. In the sixth embodiment, a ceramic 28 having a high thermal conductivity is interposed between the thermal head 11 and the thermoelectric cooling element 18 in the first embodiment. Therefore, the temperature distribution of the thermal head 11 becomes uniform,
Further, heating and cooling of the thermal head 11 by the thermoelectric cooling element 18 are performed efficiently and evenly over the entire thermal head 11, and variations in temperature of the thermal head 11 are reduced.

[0058]

As described above, according to the first aspect of the invention, the ink sheet having the ink layer is heated by the thermal head for generating the heat pattern according to the image recording information, and the ink sheet is changed to the image receiving paper. Detecting the temperature of the thermal head in a thermal transfer recording apparatus that records image information or directly heats the image receiving paper by a thermal head that generates a heat pattern according to the image recorded information to record the image information on the image receiving paper. Since the temperature detecting means and the thermoelectric cooling element for controlling the temperature of the thermal head controlled by the temperature detected by the temperature detecting means are provided, when image recording is performed in a low temperature environment or when image recording is started. When the temperature of the thermal head is not high enough, you can solve the problem that the thermal head is heated and the recorded image is faint. Heat storage behavior to the thermal head in a continuous indicia shooting operation or the like can be to cool the thermal head woke, it is possible to prevent deterioration of Shirushiutsushi image quality.

According to a second aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, a plurality of thermoelectric cooling elements and a plurality of thermoelectric cooling elements facing each other as the temperature detecting means and the thermoelectric cooling elements are provided. Since the temperature detecting means is provided and the plurality of thermoelectric cooling elements are independently controlled by the temperatures detected by the plurality of temperature detecting means, if local heat accumulation occurs in the thermal head, that portion is intensively cooled. As a result, the temperature of the entire thermal head can be made uniform.

According to the third aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, since the Peltier element is used as the thermoelectric cooling element, the thermal head is easily controlled by controlling the current of the Peltier element. The temperature of can be controlled.

According to a fourth aspect of the invention, in the thermal transfer recording apparatus according to the first aspect, the electric power to the thermoelectric cooling element is controlled so as to keep the temperature of the thermal head within a predetermined range. Therefore, the power consumed by the thermoelectric cooling element can be reduced, and a stable image can be obtained.

According to a fifth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the temperature detecting means has a plurality of temperature detecting means for detecting temperatures at a plurality of positions of the thermal head. If at least one of the temperatures detected by the temperature detecting means is within a predetermined temperature range, the thermoelectric cooling element heats the thermal head, and conversely, one of the temperatures detected by the plurality of temperature detecting means. However, when the temperature exceeds a predetermined temperature range, the thermoelectric cooling element cools the thermal head, so that it is possible to eliminate a locally low temperature portion or a high temperature portion of the thermal head, and thus a temperature variation in the thermal head. Can be prevented.

According to the sixth aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, since the heat emission side of the thermoelectric cooling element is attached to the frame of the thermal transfer recording apparatus, the size of the apparatus is changed. It is possible to increase the area of the heat dissipation and heat absorption portions without increasing the efficiency of heating or cooling the thermal head.

According to the invention of claim 7, in the thermal transfer recording apparatus of claim 1, a substance having a high thermal conductivity is interposed between the heat absorbing side of the thermoelectric cooling element and the thermal head. The temperature distribution of the thermal head can be made uniform, and further, the heating and cooling by the thermoelectric cooling element of the thermal head can be performed efficiently and evenly over the entire thermal head to reduce the variation in the temperature of the thermal head. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a thermal head temperature control unit in a first embodiment of the present invention.

FIG. 2 is a front view showing the outline of the first embodiment.

FIG. 3 is a flowchart showing a temperature control flow of the controller in the first embodiment.

FIG. 4 is a characteristic diagram showing a temperature change of a thermal head.

FIG. 5 is a perspective view showing a part of a second embodiment of the present invention.

FIG. 6 is a diagram for explaining the second embodiment.

FIG. 7 is a flow chart showing a temperature control flow of the controller in the third embodiment of the present invention.

FIG. 8 is a flowchart showing a part of a temperature control flow of the controller in the fourth embodiment of the present invention.

FIG. 9 is a flowchart showing another part of the temperature control flow of the controller in the fourth embodiment.

FIG. 10 is a front view showing the outline of a fifth embodiment of the present invention.

FIG. 11 is a perspective view showing a part of a sixth embodiment of the present invention.

FIG. 12 is a characteristic diagram showing a relationship between ink heating temperature and ink density.

[Explanation of symbols]

 17 Temperature Detection Element 18 Thermoelectric Cooling Element 22 Controller 23 Power Control Circuit

Claims (7)

[Claims] 1. An ink sheet having an ink layer is heated by a thermal head that generates a heat pattern according to image recording information and image information is recorded from the ink sheet onto an image receiving paper, or heat according to the image recording information is generated. In a thermal transfer recording apparatus for directly recording image information on an image receiving sheet by directly heating the image receiving sheet with a thermal head that generates a pattern, temperature detecting means for detecting the temperature of the thermal head and temperature detected by the temperature detecting means are used. A thermal transfer recording apparatus comprising: a thermoelectric cooling element that controls the temperature of the thermal head. 2. The thermal transfer recording apparatus according to claim 1,
As the temperature detecting means and the thermoelectric cooling element, a plurality of thermoelectric cooling elements and a plurality of temperature detecting means, which face each other in each section, are provided, and the plurality of heats are independently detected by the temperature detected by the plurality of temperature detecting means. A thermal transfer recording apparatus characterized by controlling an electronic cooling element. 3. The thermal transfer recording apparatus according to claim 1,
A thermal transfer recording apparatus, wherein a Peltier element is used as the thermoelectric cooling element. 4. The thermal transfer recording apparatus according to claim 1,
A thermal transfer recording apparatus, characterized in that power to the thermoelectric cooling element is controlled so as to keep the temperature of the thermal head within a predetermined range. 5. The thermal transfer recording apparatus according to claim 1,
As the temperature detecting means, a plurality of temperature detecting means for detecting temperatures at a plurality of locations of the thermal head are provided, and even if one of the detected temperatures of the plurality of temperature detecting means is within a predetermined temperature range, the heat The thermoelectric cooling element heats the thermal head, and conversely, the thermoelectric cooling element cools the thermal head if at least one of the temperatures detected by the plurality of temperature detecting means exceeds a predetermined temperature range. Characteristic thermal transfer recording device. 6. The thermal transfer recording apparatus according to claim 1,
A thermal transfer recording apparatus, wherein a heat emitting side of the thermoelectric cooling element is attached to a frame of the thermal transfer recording apparatus. 7. The thermal transfer recording apparatus according to claim 1,
A thermal transfer recording apparatus, wherein a substance having a high thermal conductivity is interposed between the thermal absorption side of the thermoelectric cooling element and the thermal head.