JPH11277784A - Thermal head and printer employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head in which heat absorption can be varied automatically depending on heat generation (heat storage). SOLUTION: A heating element 1 having negative temperature characteristics (NTC characteristics) is connected electrically in parallel with a heat absorbing element, i.e., a Peltier element 11. A large current flows through a Peltier element 11 connected in series with a high temperature heating element 1 to increase heat absorption of the Peltier element 11. A small current flows through a Peltier element 11 connected in series with a low temperature heating element 1 to decrease heat absorption of the Peltier element 11. Heat absorption varies automatically depending on the fluctuation of heat generation of each heating element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a thermal head and a printing apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, a serial type thermal head in which a plurality of heating resistance elements are arranged in a line in a vertical direction (recording paper feeding direction) is scanned in a horizontal direction of a recording paper to form a scan recording line. 2. Description of the Related Art There has been known a printing apparatus in which an image is formed on a recording sheet by repeating printing and printing of a scanning recording line. There is also known a line type thermal head in which a plurality of heating resistance elements are arranged in a row in a horizontal direction (width direction of recording paper).

FIG. 11 shows a conventional thermal head. A glass-based grace layer 55 is laminated as an insulating layer on a substrate 56 formed of a ceramic such as alumina, and a common electrode 58 and a control lead wire 52 are provided thereon by a vacuum evaporation method so as to face each other. The heating resistance element 51 is formed by silk screen printing so as to be orthogonal to these. In such a configuration, when a voltage is selectively applied to the control lead wire 52 from the outside,
The heating resistance element 51 between the applied control lead wire 52 and the common electrode 58 generates heat, and the generated heat causes the carbon of the transfer ribbon to be dissolved and sublimated, so that the dissolved carbon is transferred to recording paper, or the heat-sensitive paper is heated. The ink capsule is ruptured and printing is performed.

[0004] A temperature of about 80 ° C or higher is required for dissolving carbon and breaking ink capsules. To perform stable printing, a temperature within a certain temperature range, for example, 120 ° C to 14 ° C, is required.
The temperature must be raised to within 0 ° C. Conversely, when printing is not performed, unless the temperature is lowered below 80 ° C., a printing effect appears and the recording paper is soiled. In order to realize high-speed printing, it is necessary to quickly raise the temperature after energization, and to quickly cool after stopping the energization. But,
It is customary to rely on natural cooling for cooling, and in such natural cooling, heat tends to accumulate, and there is a difference in the rising temperature between dots that are printed continuously and dots that are not printed. There is a problem that quality is reduced.

In order to solve such a problem, a heat radiating plate for increasing the efficiency of natural cooling so as to adjust the maximum temperature of the dots to be within a certain range and to make the minimum temperature be equal to or lower than a certain temperature. Or an applied pulse control means for changing the power pulse width according to the heat generation history of the dot to change the power supplied to the dot. However, in the case of high-speed printing, a long cooling time cannot be taken, and it is no longer possible to prevent printing unevenness due to an increase in the maximum temperature due to heat storage using only a heat sink. In addition, when continuous high-speed printing is performed for a long time, it is difficult to keep the maximum dot temperature within a certain range by adjusting the power pulse width by controlling the applied pulse.

FIG. 12 is an explanatory diagram showing the relationship between the temperature of the heating resistor and the driving pulse of the heating resistor. The printing cycle of one pixel includes a drive pulse period for rising heating, a drive pulse period for gradation expression, and a cooling period. For high-speed printing, this one-pixel printing period must be shortened. However, if the startup heating drive pulse period is shortened, the temperature of the heating resistor element does not rise to a predetermined temperature, When the driving pulse for gradation expression is reduced, the gradation is reduced and the image quality is degraded. When the cooling period is shortened, the heat generation is performed as shown by a dashed line in FIG. The resistance element cannot be sufficiently cooled, and the heat storage of the head increases.

Therefore, a structure has been proposed in which a heat absorbing element (such as a Peltier element) which exerts a heat absorbing effect by energization is provided in order to positively absorb the heat generated by the heating resistor element 51. For example, JP-A-5-246060 (IPC)
B41J 2/335) or a line thermal head disclosed in JP-A-5-238035 (I).
PCB41J 2/345). The line thermal head disclosed in the former of the above two publications is configured such that a Peltier element is provided for each dot, and when a current is applied to each heating resistor element, the corresponding Peltier element is also energized. The heat is absorbed by the Peltier element on the surface opposite to the printing surface requiring heat. On the other hand, the thermal head disclosed in the latter publication causes the Peltier element to generate heat by energizing each heating resistor element when energizing each heating resistor element, and applies a reverse current to the Peltier element when stopping energization to the heating resistor element. It is configured to flow and absorb heat.

[0008]

However, the thermal heads disclosed in the above two publications have a configuration in which only a certain amount of heat is absorbed by the heat absorbing element, and the inside of the head is compared with a case where there is no heat absorbing element. Although the heat storage can be reduced, the amount of heat absorbed by each heat absorbing element is not changed in accordance with the variation in the amount of heat generated by each heat generating resistance element. Therefore, it is not possible to prevent variations in heat storage in the direction in which the heating resistor elements are arranged, and there is a disadvantage that uneven density occurs in the direction in which the heating resistor elements are arranged. Furthermore, in the latter technique, a coil or the like for changing the direction of the current is required,
The head becomes larger.

In view of the above circumstances, it is an object of the present invention to provide a thermal head capable of automatically changing the amount of heat absorption according to the amount of heat generation (heat storage amount).

[0010]

According to another aspect of the present invention, there is provided a thermal head including a plurality of heating resistance elements arranged in a predetermined direction. It has a heat resistance characteristic to reduce the resistance value, and a heat absorbing element is electrically connected in series to each heat generating resistance element having such a characteristic.

With the above configuration, a large amount of current flows through the heat absorbing element connected in series to the high-temperature heat-generating resistance element, so that the amount of heat absorbed by the heat absorbing element increases. on the other hand,
Since a small current flows through the heat-absorbing element connected in series to the low-temperature heat-generating resistance element, the heat-absorbing amount of the heat-absorbing element becomes small. Therefore, the amount of heat absorbed by each heat absorbing element can be changed according to the variation in the amount of heat generated (heat storage amount) of each heating resistor.

A drive element is provided for each heat-generating resistor element and each heat-absorbing element, and a drive element connected to the heat-generating resistor element to be heated is turned on during the heat drive period, and is turned on during the cooling period. Control means for turning on a driving element connected to a heat absorbing element corresponding to the heat generating resistance element that has generated heat may be provided.

In such a configuration, the heating resistor element that has generated heat during the heating driving period is also energized during the cooling period to generate heat. The amount of heat absorbed by the heat absorbing element can be exceeded, and a cooling effect higher than natural cooling can be expected.

Two types of power supply units having different supply voltage values;
The power supply unit may be configured to include a switch unit that switches between a power supply unit during the heat generation driving period and a power supply unit during the cooling period. Which side has the larger voltage value depends on
It is determined by the balance between the voltage-heat generation characteristic of the heat generating resistance element and the voltage-heat absorption characteristic of the heat absorption element.

Further, the thermal head according to the present invention is a thermal head in which a plurality of heating resistance elements are arranged in a predetermined direction, wherein the heating resistance elements have a heat resistance characteristic of increasing the resistance value when the temperature rises. A heat absorbing element is electrically connected in parallel to each of the heat generating resistance elements having characteristics.

With the above configuration, a large current flows through the heat absorbing element connected in parallel to the high-temperature heat-generating resistance element, so that the heat absorbing element has a large amount of heat absorption. on the other hand,
Since a small current flows through the heat-absorbing element connected in parallel to the low-temperature heat-generating resistance element, the amount of heat absorbed by the heat-absorbing element decreases. Therefore, the amount of heat absorbed by each heat absorbing element can be changed in accordance with the variation in the amount of heat generated by each heating resistor.

If the heat absorbing element is provided on the surface of the heating resistor element opposite to the printing surface, the heat for printing is applied to the paper side while the excess heat generated on the opposite side of the printing surface is generated. It becomes possible to absorb heat.

In a thermal head according to the present invention, a plurality of heating resistance elements are arranged in a predetermined direction. One end of the heat absorbing means is electrically connected to a common electrode of the heating resistance element, and the other end is electrically connected to a power supply unit. It is characterized by being connected. It is desirable that a heat radiating plate is attached to the heat absorbing means.

According to the above configuration, a current proportional to the number of heat-generating resistance elements that are energized to generate heat flows through the common electrode. Therefore, the heat absorbing means provided between the common electrode and the power supply is provided. In addition, since a current proportional to the number of heat-generating resistance elements that generate heat flows, heat absorption ability that is proportional to the number of heat-generating resistance elements that generate heat is exhibited. Further, as compared with the case where a heat absorbing element is formed corresponding to each heating resistance element, manufacture is easier and the yield is improved. Further, the heat transferred by the heat absorbing means is efficiently radiated by the radiator plate.

In such a configuration, if a heating resistance element having a thermal resistance characteristic of decreasing its resistance value when the temperature rises is used, even if the same number of heating resistance elements are energized, the common current depends on the degree of heat storage. The value changes,
The amount of heat absorbed by the heat absorbing means can be changed according to the amount of heat generated (heat storage amount). Further, the heat absorbing means may be divided into a plurality of parts in the direction in which the heating resistance elements are arranged.

[0021]

(Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a thermal head according to this embodiment. The upper side of this figure is the printing surface. A glass-based glaze layer 5 is laminated on an insulating and highly heat-insulating substrate 6. On the glaze layer 5, a large number of heat generating resistance elements 1 having NTC (a heat resistance characteristic of lowering the resistance value when the temperature rises) are formed in a line in a predetermined direction. Further, a common electrode 8 connected to all of them is formed on one end side (left side in the figure) of the heating resistor element 1 and individually formed on the other end side (right side in the figure). Is formed to be connected to the control lead wire 2. The control lead wire 2 penetrates the substrate 6 and extends to the rear surface of the substrate. Of the control lead wires 2 extending on the rear surface side of the substrate, a control lead wire connected to a transistor Qc described later is denoted by reference numeral 2a, and a control lead wire connected to the transistor Qp is denoted by reference numeral 2b. I have. The control lead wire 2a and the control lead wire 2b are insulated by the insulating layer 9.

On the opposite side of the glaze layer 5 (on the opposite side of the printing surface), a Peltier element (heat absorbing element) 11 is arranged and formed at the same resolution as the arrangement resolution of the heating resistor element 1. This Peltier element 11 is a p-type thermoelectric semiconductor 11c.
And an n-type thermoelectric semiconductor 11b and an electrode 11a for electrically connecting them, and are connected in a π-type (or an inverse π-type) as shown in FIG. Although the Peltier element 11 is embedded in the substrate 6 in this embodiment, the present invention is not limited to this, and the Peltier element 11 may be embedded in another member having an insulating property and a high heat insulating property.

FIG. 2 is an enlarged view of the Peltier element 11. When a DC current is applied to the Peltier element 11, heat is transferred in the direction of the current in the case of a p-type thermoelectric semiconductor, and heat is transferred in the direction opposite to the current in the case of an n-type heat semiconductor. A temperature difference occurs at both ends (upper and lower sides in the figure). Each thermal semiconductor and the electrodes 11a, 2, 2a are bonded by a solder layer. Further, since the electrodes of the adjacent Peltier elements 11 need to be insulated from each other, such electrodes are fixed to, for example, a ceramic insulating plate. Generally, copper (Cu) is used for the electrode, a bismuth tellurium-based compound semiconductor is used as the n-type heat semiconductor, and a bismuth-antimony-tellurium-based compound semiconductor is used as the p-type heat semiconductor. Such compound semiconductors are currently considered to have the best performance near room temperature.

FIG. 3 is a circuit diagram showing a connection relationship among the heating resistor element 1, Peltier element 11, and transistors Qp and Qc as driving elements of the thermal head. The common electrode 8 is connected to the switch 16. By operating this switch 16, it is possible to control such that the first power supply unit 14 is selected during the heat generation driving period and the second power supply unit 15 is selected during the cooling period. How to set the potentials of the power supply units 14 and 15 is as follows.
Voltage-heating characteristics of heating resistor element 1 and Peltier element 11
Is determined by the balance between the voltage and the endothermic characteristic. The transistor Qp is connected to the heating resistor 1 for driving the heating resistor 1, and the transistor Qc is connected to the Peltier device 1.
1 is connected to the element 11 for driving. On the basis of the print signal, the transistor Qp connected to the heating resistor element 1 to be heated during the heating driving period is turned on, and the transistor Qp is turned off during the cooling period and corresponds to the heating resistor element 1 that has been heated. The transistor Qc connected to the provided Peltier element 11 is turned on. Such control is performed by drive control means (including a driver circuit, a latch circuit, a shift register circuit, etc.) not shown.

FIG. 4A is an explanatory diagram when the temperature of the heating resistor 1 is high, and FIG. 4B is an explanatory diagram when the temperature of the heating resistor 1 is low. When the temperature of the heating resistance element 1 is high, the Peltier element 11 connected in series to the heating resistance element 1
A large current I flows through the Peltier element 11
Endothermic amount becomes large. On the other hand, when the temperature of the heating resistance element 1 is low, the Peltier element 11 connected in series
Since a small current flows through the Peltier element 11, the amount of heat absorbed by the Peltier element 11 is reduced. FIG. 5 schematically illustrates this description. As can be seen from this schematic diagram and the above description,
The amount of heat absorbed by each Peltier element 11 automatically changes in accordance with the variation in the amount of heat generated by each heating resistor element 1.
Therefore, it is possible to avoid variations in heat storage in the direction in which the heating resistor elements are arranged, and to prevent the occurrence of density unevenness in the direction in which the heating resistor elements are arranged. In addition, since an extra member such as a coil is not required, an increase in the size of the thermal head can be prevented. Furthermore, the banding phenomenon that tends to occur in the serial type printing apparatus, that is, since the central portion of the head has a larger heat storage than the upper and lower portions, the density between adjacent scanning recording lines is low, and "streaks" occur. The phenomenon that appears to have occurred can also be prevented.

In the above configuration, heat is generated in the heating resistor element 1 which has been generating heat during the heating driving period, and the heating resistor element 1 is also energized during the cooling period. The amount of heat absorbed by the Peltier element 11 can be made larger than this heat generation amount, and a cooling effect higher than natural cooling can be expected. Here, the transistor Qp
A configuration in which the transistor Qp among the transistors Qc and Qc is omitted is conceivable. In the case of this configuration, the insulating layer 9 and the lead wire 2b are unnecessary in FIG. With such a configuration, it is possible to cause the heating resistor element 1 to generate heat during the heating driving period and to apply heat for printing to the paper side, while absorbing excess heat (particularly, heat generated on the side opposite to the printing surface). Will be possible. When a Peltier element is used as the heat absorbing element, by providing a means for switching the direction of the current flowing through the Peltier element, heat can be generated in the Peltier element during periods other than the cooling period. This makes it possible to perform preheating by causing the Peltier element 11 to generate heat.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG. The same members as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the thermal head of this embodiment, a heating resistor element 1 'and a Peltier element 11' are connected in parallel. That is, a common electrode 8 is formed above and below the substrate 6 on the left side of the figure, and is connected to a power supply. On the right side of the drawing, a control lead wire 2 connected to one end of the heating resistor element 1 ′ and the Peltier element 11 ′ forming a pair is formed. The control lead wire 2 is formed by an insulating film 9. It extends on the left side of the figure without contacting the lower common electrode 8. The heat generating resistance element 1 'has PTC characteristics (thermal resistance characteristics that increase its resistance value when the temperature rises). Then, the p-type thermoelectric semiconductors 11c and n in the Peltier element 11 '
The arrangement of the type thermoelectric semiconductor 11b is opposite to that of FIG.

With such a configuration, a large current flows through the Peltier element connected in parallel to the high-temperature heating resistor element 1 ', so that the Peltier element 11' absorbs a large amount of heat. On the other hand, since a small current flows through the Peltier element 11 'connected in parallel with the low-temperature heating resistor element 1', the heat absorption of the Peltier element 11 'becomes small. Therefore, the amount of heat absorbed by each Peltier element 11 'changes in accordance with the variation in the amount of heat generation (the amount of heat storage) of each heating resistor element 1', and the variation in heat storage in the direction in which the heating resistor elements are arranged is avoided. It is possible to prevent the occurrence of density unevenness in the direction in which the heating resistance elements are arranged.

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 7A is a plan view of the thermal head of this embodiment, and FIG. 7B is a cross-sectional view taken along the line AA of FIG. In addition,
Members having the same functions as in the first embodiment are denoted by the same reference numerals.

A heat absorbing block 11A is provided at a position facing away from the heating resistor 1 with the substrate 6 interposed therebetween, divided into four in the direction in which the heating resistor 1 is arranged. The common electrode 8 is also divided into four parts corresponding to this division. A radiator plate 7 is attached to a lower surface side (a side where heat is transferred) of the heat absorbing block 11A.

FIG. 8 is a sectional view showing the heat absorbing block 11A. The heat absorbing block 11 </ b> A is configured by continuously arranging a plurality of Peltier elements 11 in a direction orthogonal to the direction in which the heating resistance elements 1 are arranged. Alternatively, although not shown in the drawing, the heat absorbing block 11 </ b> A is configured by continuously arranging a plurality of Peltier elements 11 in the direction in which the heating resistance elements 1 are arranged. Each Peltier element 11 has the basic structure shown in FIG.
It operates to transfer the heat of the side to the heat sink 7 side.

FIG. 9 shows a heat absorbing block 11A, a common electrode 8, a heating resistor 1 connected to the common electrode 8, and a transistor Q as a driving device connected to the heating resistor 1.
FIG. 4 is a circuit diagram showing a connection relationship with p. Power supply unit 15
A heat absorbing block 11 </ b> A exists between the common electrode 8 and the heat absorbing block 11 </ b> A. The plurality of heating resistance elements 1 are connected to each common electrode 8. The control of the transistor Qp is performed by control means (including a driver circuit, a latch circuit, a shift register circuit, and the like) not shown.

FIG. 10A is an explanatory diagram in the case where the number of the heating resistor elements 1 driven to be heated (ON) is large in the heat absorbing block 11A, and FIG.
FIG. 7 is an explanatory diagram in the case where the number of heating resistance elements 1 to be performed is small. When the number of the heat-generating resistance elements 1 to be turned on is large, a large current I flows according to the number of the heat-absorbing blocks 11A.
On the other hand, when the number of the heating resistance elements 1 to be turned on is small, a small amount of current flows through the heat absorbing block 11A, so that the heat absorbing amount of the heat absorbing block 11A decreases. That is, the heat absorption amount of each heat absorbing block 11A automatically changes in accordance with the number of the heat generating resistance elements 1 that are driven to generate heat. With such a structure, compared with the configuration of the first embodiment in which a Peltier element is formed corresponding to each heating resistance element,
Since the miniaturization of the Peltier element is eased, the yield is improved and the manufacture is facilitated.

Further, in this embodiment, since the heating resistor element 1 having NTC characteristics is used, even when the same number of heating resistor elements are energized, the common current value changes depending on the degree of heat storage, and the heat absorbing block 11A Can be changed.

Here, instead of adopting a structure of dividing the heat absorbing block into four heat absorbing blocks 11, a single plate-shaped heat absorbing means integrating these may be provided. The heat is not absorbed intensively in that part, but is absorbed in the entire surface. On the other hand, if a Peltier element is provided corresponding to each heating resistance element, the Peltier element must be miniaturized as described above. As shown in FIG. 7 of this embodiment,
In the case where the divided configuration including the plurality of heat absorbing blocks 11A is adopted, heat can be absorbed to a certain extent in the heat storage portion, and miniaturization of the Peltier element can be alleviated.

Although not shown, the printing apparatus of the present invention is provided with the above-described thermal head (serial type or line type). It may be in any form of dissolving and sublimating carbon and transferring the dissolved carbon to recording paper, or in a form of printing by bursting an ink capsule of thermal paper, or in any other form. . As the overall configuration, the configuration shown in FIG. 13 can be applied. Note that FIG.
FIG. 4 is a circuit diagram showing a circuit that can be considered when a heating resistor element having NTC characteristics is used and the temperature of the heating resistor element is detected to perform thermal control correction (strobe signal waveform control).

[0038]

As described above, if the heat-absorbing element is electrically connected in series to each of the heat-generating resistance elements having the NTC characteristic, it is possible to cope with the variation in the calorific value of each heat-generating resistance element. As a result, the amount of heat absorbed by each heat absorbing element changes, so that it is possible to avoid a variation in heat storage in the direction in which the heating resistance elements are arranged, and to prevent the occurrence of density unevenness in the direction in which the heating resistance elements are arranged.

A driving element is provided for each heating resistor element and each heat absorbing element, and the driving element connected to the heating resistor element to be heated is turned on during the heating driving period, and is turned on during the cooling period. With a configuration including a control unit that turns on the driving element connected to the heat absorbing element corresponding to the heat generating resistance element that has generated heat, the heating resistance element that has generated heat during the heat generation driving period can generate heat even during the cooling period. The resistance element is energized to generate heat, but the amount of heat absorbed by the heat-absorbing element exceeds this amount of heat generation, and a cooling effect higher than natural cooling can be expected.

Two kinds of power supply units having different supply voltage values,
A switch means for switching between a power supply unit during the heat generation driving period and a power supply unit during the cooling period; applying an appropriate voltage to the heating resistance element during the heat generation driving period; An appropriate voltage can be applied to the element.

If the heat-absorbing element is electrically connected in parallel to each of the heat-generating resistance elements having the PTC characteristic, the heat-absorbing quantity of each heat-absorbing element corresponds to the variation in the calorific value of each heat-generating resistance element. , The variation in heat storage in the direction in which the heating resistor elements are arranged can be avoided, and the occurrence of uneven density in the direction in which the heating resistor elements are arranged can be prevented.

If the heat absorbing element is provided on the surface of the heating resistor opposite to the printing surface, extra heat accumulated on the opposite side of the printing surface while applying heat for printing to the paper side. It becomes possible to absorb heat.

In a configuration in which one end of the heat absorbing means is electrically connected to the common electrode of the heat generating resistance element and the other end is electrically connected to the power supply section, the heat absorbing means corresponds to the number of heat generated by each heat generating resistance element. Will automatically change. Also,
Compared to the case where a heat absorbing element is formed corresponding to each heat generating resistance element, the miniaturization of the heat absorbing element is eased, so that the yield is improved and the production is facilitated. With a configuration in which a heat radiating plate is attached to the heat absorbing means, the heat transferred by the heat absorbing means can be efficiently radiated. When a heating resistor having NTC characteristics is used, there is an effect that even when the same number of heating resistors are energized, the common current value changes depending on the degree of heat storage, and the amount of heat absorbed by the heat absorbing means can be changed.

[0044]

[Brief description of the drawings]

FIG. 1 is a sectional view of a thermal head according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a Peltier element which is a heat absorbing element of the present invention.

FIG. 3 is a diagram in which a transistor is added to the equivalent circuit of FIG. 1;

FIG. 4 is an explanatory diagram showing the relationship between the temperature of the heat-generating resistance element having the NTC characteristic of FIG. 1 and the amount of heat absorbed by the Peltier element.

FIG. 5 is an explanatory diagram schematically showing FIG. 4;

FIG. 6 is a sectional view of a thermal head according to a second embodiment of the present invention.

FIG. 7A is a plan view of a third embodiment of the present invention, and FIG. 7B is a cross-sectional view taken along the line AA of FIG. 7A.

FIG. 8 is a detailed view of the heat absorbing block of FIG. 7;

FIG. 9 is a diagram in which transistors are added to the equivalent circuit of FIG. 7;

FIG. 10 is an explanatory diagram schematically showing the relationship between the temperature of the heat-generating resistor element having the NTC characteristic shown in FIG. 7 and the amount of heat absorbed by the Peltier element.

FIG. 11 is a sectional view of a conventional thermal head.

FIG. 12 is an explanatory diagram showing a relationship between a temperature of the heating resistor and a driving pulse of the heating resistor.

FIG. 13 is a circuit diagram showing a general circuit that can be considered when a heating resistor having NTC characteristics is used and the temperature of the heating resistor is detected to perform thermal control correction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat generation resistance element (NTC characteristic) 1 'Heat generation resistance element (PTC characteristic) 2 Control lead wire 5 Glaze layer 6 Substrate 7 Heat sink 8 Common electrode 9 Insulation layer 11 Peltier element (heat absorption element) 11a Electrode 11b n-type thermoelectric semiconductor 11c p-type thermoelectric semiconductor 11A heat absorbing block (heat absorbing means)

Claims (11)

[Claims] 1. A thermal head comprising a plurality of heating resistance elements arranged in a predetermined direction, wherein the heating resistance elements have a heat resistance characteristic of decreasing the resistance value when the temperature rises, and each heating resistance element having such a characteristic. A thermal head, wherein a heat absorbing element is electrically connected in series. 2. A driving element is provided for each heat-generating resistance element and each heat-absorbing element, and a driving element connected to the heat-generating resistance element to be heated is turned on during a heat driving period, and a cooling period is set. 2. The thermal head according to claim 1, further comprising control means for turning on a driving element connected to the heat absorbing element corresponding to the heat generating resistance element that has generated heat. 3. A power supply unit comprising two types of power supply units having different supply voltage values, and switch means for switching between a power supply unit during the heating driving period and a power supply unit during the cooling period. 3. The thermal head according to 2. 4. A thermal head comprising a plurality of heating resistance elements arranged in a predetermined direction, wherein the heating resistance elements have a heat resistance characteristic of increasing the resistance value when the temperature rises, and each heating resistance element having such a characteristic. A thermal head, wherein a heat absorbing element is electrically connected in parallel with the thermal head. 5. The thermal head according to claim 1, wherein the heat absorbing element is provided on a surface of the heating resistor element opposite to a printing surface. 6. A thermal head comprising a plurality of heating resistance elements arranged in a predetermined direction, wherein one end of the heat absorbing means is electrically connected to a common electrode of the heating resistance element, and the other end is electrically connected to a power supply. Thermal head. 7. The thermal head according to claim 6, wherein a heat radiating plate is attached to said heat absorbing means. 8. The thermal head according to claim 6, wherein said heat generating resistance element has a heat resistance characteristic of decreasing its resistance value when the temperature rises. 9. The device according to claim 6, wherein the heat absorbing means is divided into a plurality of parts in the direction in which the heating resistance elements are arranged, and the common electrode is also divided in accordance with the division. The thermal head according to any one of the above. 10. The heat absorbing element or the heat absorbing means has a Peltier characteristic.
The thermal head according to any one of the above. 11. A printing apparatus comprising the thermal head according to claim 1.