JPH04355164A - Thermal head - Google Patents

Abstract

PURPOSE:To provide a thermal head simplified in constitution, reduced in the number of components and enhanced in reliability. CONSTITUTION:A large number of the heating resistors on an insulating substrate 23 are divided into groups at every 2N resistors and one end parts of heating resistors P at every pairs are electrically connected and individual electrodes 29 are connected to the other end parts thereof. The adjacent heating resistors Pa are mutually connected in common through diodes 58 and the other heating resistors Pb1, Pb2 of the adjacent heating electrodes P are respectively connected to the connection wirings 50,51 in a diode array element 30. Rectifying elements at every pairs connected in common at the output terminals thereof are respectively connected to N switching elements 62 built in a driven circuit element 33.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head, and more particularly to a line thermal head that simultaneously prints over the entire range of one line of recording paper.

0002

2. Description of the Related Art FIG. 15 is a block diagram of a typical conventional thermal head 1. In the thermal head 1, a heating resistor 4 is connected to each end of a plurality of branch electrodes 3 connected to a common electrode 2, and a power source, for example, is connected to the other end of each heating resistor 4 via an individual electrode 5. Switching elements 6 such as transistors are individually connected. The output terminal of each switching element 6 is commonly connected to a ground wiring 7, and the control signal input terminal of each switching element 6 is connected to an AND element 8, respectively.

The switching element 6 and the AND element 8 are drive circuit elements 9 formed by integrated circuit technology.
A shift register 10 and a latch circuit 11 are further formed within the drive circuit element 9.

Display data D is input to the shift register 10 in the form of a serial signal together with a clock signal CK, and a latch signal LT is input to the latch circuit 11 at a predetermined timing to latch the data in the shift register 10. Thereafter, the strobe signal SB is commonly input to each AND element 8, and the display data latched in the latch circuit 11 is outputted to the switching element 6. The switching element 6 is set to a conductive or cut-off state according to display data, and when the switching element 6 is in a conductive state, current from the common electrode 2 flows through the heating resistor 4 to the ground wiring 7, and this heating resistor 4
is driven by heat.

FIG. 16 shows another conventional thermal head 1a.
FIG. 17 is a block diagram showing the electrical configuration of the thermal head 1a, and FIG. 17 is a perspective view of the thermal head 1a. This conventional example is similar to and corresponds to the conventional example described above, and the same reference numerals are given to the same parts. The thermal head 1a includes an insulating substrate 12 made of an electrically insulating material.
A pair of common electrodes 2a and 2b are formed thereon, spaced apart from each other. Branch electrode 3b from common electrode 2b
are connected to every other heating resistor 4 on the glaze layer 13 formed on the insulating substrate 12. On the other hand, the common electrode 2a is connected to the branch electrodes 3a disposed between the branch electrodes 3b, and is connected to the heat generating resistors 4 between the heat generating resistors 4 defined by the branch electrodes 3b. Branch electrode 3a
An insulating layer 14 is provided between each branch electrode 3 and the common electrode 2b.
It is formed every a.

Further, as shown in FIG. 16, between the common electrodes 2a, 2b and the heating resistor 4, there are common electrodes 2a, 2b,
A diode array 17 is arranged in which a diode 15 whose anode 2b is connected to each heating resistor 4 is connected. The other ends of the adjacent heat generating resistors 4 connected to the common electrodes 2a and 2b are connected in common and are respectively connected to an AND element 16 provided in the drive circuit element 9 via the individual electrodes 5.

In this conventional example, in order to sequentially drive the adjacent heating resistors 4, power is applied alternately to the common electrodes 2a and 2b, and the drive circuit element 9 receives the power at the corresponding timing. The heat-generating resistor 4 is energized and driven in accordance with display data.

Furthermore, when driving power is supplied to the common electrode 2a, correspondingly, the driving current flows only to the heating resistor 4, and the driving current flows to the adjacent heating resistor 4 connected to the same individual electrode 5. Each diode 15 performs a backflow prevention function so that the drive current does not flow undesirably.

[0009]

[Problems to be Solved by the Invention] In the first conventional example, the drive circuit element 9 needs to be provided with the same number of output transistors as the number of heat generating resistors 4 provided in the thermal head 1, and the number of output transistors is As the number of components increases, the configuration of the drive circuit element 9 becomes complicated, and the number of elements also increases, resulting in an increase in the number of parts, mounting man-hours, and cost.

In a second conventional example, a diode array 17 in which each diode 15 is formed is placed on the insulating substrate 12.
This poses a problem in that the thermal head 1a becomes larger. Furthermore, the heating resistors 4 of this thermal head 1a are arranged at a minute pitch P1 (100 μm as an example) as shown in FIG. 17, and it is necessary to form the insulating layer 14 at such a minute pitch. The number of manufacturing steps increases, and since the branch electrodes 3a are bent over the common electrode 2b, cracks 18 are likely to be formed, and poor connections or disconnections are likely to occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal head that solves the above-mentioned technical problems and has a significantly simplified configuration, a reduced number of parts, and improved reliability.

0012

[Means for Solving the Problems] The present invention provides a thermal head in which a plurality of heating resistors are arranged on an insulating substrate, in which a pair of heating resistors electrically connected at one end is N
M common electrode lines, which are less than N, are arranged on the insulating substrate, and the other end of one of the pair of heat generating resistors is connected to one terminal of the rectifying element. At the same time, the other end of the other heating resistor is connected to the common electrode line, and the other terminal of the rectifying element is connected to L switching elements smaller than N built in the control circuit element. A thermal head characterized by:

The present invention also provides a thermal head in which a plurality of heat generating resistors are arranged on an insulating substrate, in which N pairs of heat generating resistors each having one end electrically connected are arranged, and the above insulating substrate M common electrode lines smaller than N are arranged on the top, and the other end of one of the pair of heating resistors is connected to one terminal of the rectifying element, and the other end of the heating resistor is connected to one terminal of the rectifying element. The other end of the body is a thermal head characterized in that it is connected to L switching elements less than N, each of which is built in a control circuit element.

The present invention also provides a thermal head in which a plurality of heating resistors are arranged on an insulating substrate, in which each of the N heating resistors is provided with one electrode and the other electrode, and the N heating resistors are arranged on the insulating substrate. A small number of M common electrode lines are arranged, each of the one electrodes is connected to one terminal of a rectifying element, the other electrode is connected to the common electrode line, and the other terminal of the rectifying element is built in a control circuit element. The thermal head is characterized in that each of the thermal heads is connected to L switching elements, which are less than N switching elements.

The present invention also provides a thermal head in which a plurality of heating resistors are arranged on an insulating substrate, in which each of the N heating resistors is provided with one electrode and the other electrode, and the N heating resistors are arranged on the insulating substrate. A small number of M common electrode lines are arranged, and each of the one electrodes is connected to one terminal of a rectifying element, and each of the other electrodes is connected to L switching elements, which are smaller than N, built in the control circuit element. This thermal head is characterized by:

[0016]

According to the present invention, in the thermal head, N heating resistors are formed on an insulating substrate, and one end of each pair of heating resistors is electrically connected. Further, a rectifying element is connected to the other end of each heating resistor. M common electrode lines smaller than N are arranged on the insulating substrate on the opposite side of the heating resistor from the rectifying element. Further, the other end portions of the other heating resistors are respectively connected to the common electrode line. The output end of each rectifying element is connected to L switching elements, which are less than N, built in the control circuit element.

That is, each of the L switching elements built into the control circuit element can respectively control the N heating resistors. Further, the common electrode line is patterned on the insulating substrate on the opposite side of the heating resistor with respect to the rectifying element, and each heating resistor and the common electrode line are interconnected in a matrix within the rectifying element array.

[0018] This makes it possible to reduce the number of control circuit elements, simplifying the configuration and reducing the number of parts. Furthermore, when using a plurality of common electrode lines, it is no longer necessary to construct a multilayer wiring structure on the insulating substrate on which the heating resistor is formed, and reliability regarding electrical connections can be improved.

Furthermore, a plurality of common electrode lines to which driving power for driving each heat generating resistor to generate heat is supplied are formed on an insulating substrate and are connected to the heat generating resistor through a rectifying element array. Each of the rectifying element arrays is connected to L switching elements built in the control circuit element via the rectifying elements inside the rectifying element array. Therefore, each common electrode line and the heating resistor are prevented from being formed so as to overlap with any common electrode line, and it is possible to simplify the manufacturing process and improve reliability regarding electrical connection.

[0020]

[Embodiment] Figure 1 shows a thermal head 2 according to an embodiment of the present invention.
1, FIG. 2 is a sectional view taken along the section line X2-X2 in FIG. 1, and FIG. 3 is a plan view of the insulating substrate 23 of the thermal head 21. In the thermal head 21, an insulating substrate 23 made of ceramic such as aluminum oxide Al2O3 is mounted on a heat sink 22 made of aluminum, for example. A glaze layer 24 made of glass is formed on the insulating substrate 23, and tantalum nitride Ta2N or the like is deposited on the insulating substrate 23 using a thin film technique such as sputtering.
The resistor layer 25 is formed by depositing the resistor layer 25 to a thickness of 00 Å. Furthermore, a pattern of metal such as aluminum is formed thereon by a thin film technique such as sputtering or etching as shown in FIG.

That is, the A number (16 as an example) of heating resistors P formed on the thermal head 21 are divided into adjacent predetermined 2N (8 as an example) groups G1, G.
2, and each pair of adjacent heating resistors Pa, P
A connecting electrode member 27 is formed for each pair of heating resistors Pa and Pb to connect one common end of the heating resistors Pa and Pb.

On the opposite side of the heating resistors Pa, Pb, individual electrodes 29a, 29b are formed for each heating resistor Pa, Pb, and for each of a plurality of groups, that is, for each of the two groups G1 and G2 in this embodiment. It extends into the arrangement area 31 of each diode array element 30, and its end portion is configured as a pad portion 32.

The ends of the plurality of diode array elements 30 along the main scanning direction of the thermal head 21 are pulled out to the lower side of the insulating substrate 23 in FIG. 3 for each group G1 and G2 to form a pad part 48. A first common electrode line 28a is formed to connect each diode array element 3.
The end portion of each zero arrangement region 31 is pulled out downward in FIG. 3, and a second common electrode line 28b configured as a pad portion 49 is patterned. A plurality of pad portions 52 are provided on each of the M common electrode lines 28a and 28b (two in this embodiment) for connection with the diode array element 30.
is formed. The pad portion 32 of each individual electrode 29a, 29b is connected to the corresponding diode array element 30.

A plurality of connection conductors 35 are formed across the arrangement region 31 and the arrangement region 34 of the drive circuit element 33, each end of which is configured as a pad portion 36. Said placement area 3
4, the drive circuit element 3 is inserted from near the end of the insulating substrate 23.
A plurality of signal lines 38 having both ends configured as pad portions 37 are provided in order to supply display control signals, display data, etc. to 3, and each end portion is configured as a pad portion 40 for each arrangement area 34. A ground electrode 39 is formed.

[0025] A drive circuit element 33 is provided for each arrangement area 34.
A plurality of pad portions 53 are formed to be connected to the grounding terminals, and a ground electrode 39 whose end portion is drawn out downward in FIG. 3 to form the pad portion 40 is formed.

A wear-resistant layer 41 made of silicon nitride, Si3N4, for example, covers the heating resistor P on the insulating substrate 23.
is formed. Further, the diode array element 30 and the drive circuit element 33 have bumps 42 and 43, and a solder layer is applied to the pad portions 32, 36, 52 in the arrangement region 31 and the pad portions 36, 37, 53 in the arrangement region 34, etc. 44 by the face-down bonding method. Further, the pad portions 48, 49 of the common electrode lines 28a, 28b, the signal line 38, and the ground electrode 39,
A flexible wiring board 47 in which circuit wiring is formed on a support film made of, for example, a flexible synthetic resin material is connected to 37 and 40 via a solder layer 44.

In this embodiment, the two common electrode lines 28
a, 28b, as shown in FIG. 4, the first drive voltage VH1 is supplied to every other printing pixel element P, and the second drive voltage VH2 is supplied to the remaining every other printing pixel element P. It is something.

Moreover, the common electrode lines 28a and 28b are connected to the insulating substrate 2 on the opposite side of the heating resistor P with respect to the individual electrodes 29.
3, common electrode lines 28a, 28b are formed.
The conduction between the individual electrodes 29 and the individual electrodes 29 is established through a diode array element 30. This makes it possible to prevent the individual electrodes 4 and branch electrodes 3 from being wired in multiple layers at extremely fine pitches, as in the conventional example shown in FIG. 15, and to improve the reliability of electrical connections.

FIG. 4 is a block diagram illustrating the electrical configuration of the thermal head 21. As shown in FIG. A 2×N matrix of multilayer wiring is formed within the diode array element 30. That is, as shown in FIG. 4, one of the heating resistors P of the odd-numbered heating resistors P from the left in FIG.
A is connected to a diode 58 having the heating resistor Pa on the anode side. The other heating resistor Pb1 of the odd-numbered heating resistors P is connected to the connection wiring 50 in the diode array element 30, which is connected to the common electrode line 28a via the bump 52. On the other hand, one heating resistor Pa of the even-numbered heating resistors P is connected to a diode 58 having the other heating resistor Pa on the anode side. The other heating resistor Pb2 of the even-numbered heating resistors P is connected to the connection wiring 51 in the diode array element 30, which is connected to the common electrode line 28b via the bump 52. In other words, the other heating resistors Pb1 and Pb2 of the adjacent heating resistors P are connected to different common electrode lines 28a and 28b, respectively. The output ends of the diodes 58 corresponding to such adjacent heat generating resistors P are connected in common and connected to the N connecting conductors 35, respectively.

The drive circuit element 33 is provided with an N-bit shift register 59 and a latch circuit 60, and the output of the latch circuit 60 is sent to L transistors 62, which are switching elements, through a plurality of AND circuits 61. Connected to gate terminal. The input terminal of each transistor 62 is connected to each connection conductor 35, and
An output terminal of each drive circuit element 33 is connected to a ground electrode 39. Here, since one transistor 62 is connected to a plurality of diodes 58, the number L of such transistors 62 is smaller than the above N number.

The shift register 59 stores display data D.
is given as serial data together with a clock signal CK, and a latch signal LT and a strobe signal SB are supplied to a latch circuit 60 and an AND circuit 61. 63. Further, drive voltages VH1 and VH2 for the common electrode lines 28a and 28b are also supplied by the control section 63 as will be described later.

FIG. 5 is a timing chart showing the operation of the thermal head 21. From time t1, display data Do1 corresponding to the odd-numbered heating resistors P are input to the shift register 59 together with the clock signal CK. At this time, both the first and second drive voltages VH1 and VH2 are set to low level. At time t3, which is a predetermined period after time t2 when the display data Do1 has been input, the latch signal LT is input to the latch circuit 60, and the shift register 5
Latch the data of 9.

At time t4, which is a predetermined interval from this timing, the strobe signal SB switches from a low level to a high level, and the data from the latch circuit 60 is output to each transistor 62. At time t4, the first drive voltage VH1 is raised to a high level, current flows through each heating resistor Pa and Pb in the direction indicated by the arrow A1, and the odd-numbered heating resistor P is driven to generate heat. . At the same time, display data De1 corresponding to even-numbered heating resistors P is input to the shift register 59 together with the clock signal CK.

At time t5 when the input of the display data De1 is completed and a predetermined heating time has elapsed, the strobe signal SB is activated.
is switched from a high level to a low level, and the heating operation of the odd-numbered heating resistor P is stopped. Also, in synchronization with this, the first drive voltage VH1 is switched to low level. Thereafter, at time t6, the latch signal LT is output to the latch circuit 6.
0 and latches the display data De1. Thereafter, at time t7, the strobe signal SB is switched from low level to high level, and the second drive voltage VH2 rises from low level to high level, and after a predetermined heating period, the strobe signal SB becomes low level at time t8. Then, the second drive voltage VH2 is cut off. In this way, the odd-numbered and even-numbered heating resistors P are repeatedly driven to generate heat, and the printing operation of the thermal head 21 progresses.

At this time, the thermal head 21 has a configuration in which the N transistors 62 of one drive circuit element 33 control the 2N heating resistors P, and therefore the first
Compared to the conventional example shown in FIG.

In this embodiment, the diode array element 30 is used to control 2×N heating resistors P with a single drive circuit element 33. The circuit is insulated substrate 2
Instead of forming the circuit on 3 by photoprocessing or incorporating it into the drive circuit element 33,
Diode array element 3 realized as an integrated circuit element
We aim to achieve this within 0. Thereby, it is possible to prevent a significant change in the manufacturing process of the thermal head 21, a significant change in the internal circuit of the drive circuit element 33, or an increase in size, and it is possible to simplify the configuration.

That is, the driving circuit element 33 may be the same as the conventional driving circuit element having the number of output terminals corresponding to the number N of heating resistors P in one group G. The only change in the manufacturing process for forming the glaze layer 24, etc. is to change the pattern mask when patterning the individual electrodes 29, etc., which can prevent the manufacturing process from becoming complicated, and also improve the configuration of the drive circuit element 33. It is possible to prevent the structure from becoming more complicated and larger.

In this embodiment, the common electrode lines 28a, 2
8b is patterned on the insulating substrate 23 on the side opposite to the heating resistor P with respect to the individual electrodes 29. Moreover, the connection between each common electrode line 28a, 28b and the individual electrode 29 is made by a diode matrix circuit within the diode array element 30. This eliminates the need for multilayer wiring in the thermal head 21 on the insulating substrate 23 or on the flexible wiring board 47, which is connected from the outside, and simplifies the manufacturing process and the configuration. can be achieved. Especially the second
Compared to the conventional example, it is possible to improve reliability regarding electrical connection and improve yield.

FIGS. 6 to 8 are plan views showing other embodiments of the thermal head 21, respectively. In the above embodiment, the diode array elements 30 and the drive circuit elements 33 were arranged in the sub-scanning direction of the thermal head 21, that is, in the vertical direction in FIG. 1, but as shown in FIG. An example is possible in which the heating resistor P is shifted along the main scanning direction from near the center position in the main scanning direction, and the diode array element 30 and the drive circuit element 33 are arranged in a straight line along the main scanning direction. For this purpose, the connecting conductor 35 is bent into a crank shape.

Further, as shown in FIG. 7, the diode array element 30 is shifted from the center position along the main scanning direction,
A configuration example is possible in which the connection conductor 35 is bent into an L-shape and the drive circuit elements 33 are arranged so that the connection positions with the connection conductor 35 are along the sub-scanning direction.

FIG. 8 is a plan view of a thermal head 21a according to another embodiment of the present invention, and FIG. 9 is a plan view of a thermal head 21a according to another embodiment of the present invention.
FIG. 2 is a circuit diagram showing the electrical configuration of FIG. This embodiment is similar to the previous embodiment, and corresponding parts are given the same reference numerals. On the other hand, in this embodiment, three common electrode lines 28a, 2
8b, 28c, and connection wirings 50a, 50b, which are individually connected to these and formed within the diode array element 30.
50c is used. The other heating resistors Pb1, Pb2, Pb3 of the groups G1, G2 are connected to the common electrode line 28a,
28b and 28c, respectively. Also group G
On the other hand, the heating resistor Pa includes a diode array element 30.
A diode 58 having one side of the heating resistor Pa as an anode is connected within the diode 58a. Among the diodes 58, one is selected from those in which the other heating resistor Pb of the connected heating resistors P is connected to mutually different connection wirings 50a to 50c, and their output ends are commonly connected. , are connected to the connection conductor 35, respectively.

That is, in this embodiment, all the heating resistors P are also grouped into groups of 2N, but in this embodiment, the number N is selected to be a multiple of 3, which is the number of common electrode lines 28a to 28c. Therefore, the common electrode lines 28a,...
If the number is greater than or equal to 28, the number N is the common electrode line 28.
The number of a, . . . is selected as a multiple of 4. That is, the number of diodes 58 connected to each connection conductor 35 is the same as the number of common electrode lines 28a, . Each connection conductor 35 is
As in the previous embodiment, each of the heating resistors P of one group G and the same number of N transistors 62 are connected to each other.

That is, in this embodiment, the operation of time-sequentially applying the driving voltages VH1 to VH3 to the three common electrode lines 28a to 28c, and the operation of applying the driving voltages VH1 to VH3 to the three common electrode lines 28a to 28c, respectively, and
By combining the operation of controlling conduction/cutoff of 2, each heating resistor P can be individually controlled.

[0044] Such an embodiment can also achieve the same effects as those described in the previous embodiments.

As a modification of the above embodiment, as shown in FIG. 10, a heat generating resistor P having the same structure as that of the thermal head 21a is constructed, while being connected to the heat generating resistor Pa and the left heat generating resistor Pb. The individual electrodes 29a and 29b are respectively connected to a diode drive circuit integrated circuit 80 in which the internal circuits of the diode array element 30a and the drive circuit element 33 shown in FIG. 9 are integrally configured. Such an embodiment can also achieve the same effects as those described in the previous embodiment, and since an integrated circuit element in which the diode array element 30a and the drive circuit element 33 are integrated is used, this The installation area of such an integrated circuit element can be reduced, and this can contribute to miniaturization of the structure of the thermal head.

FIG. 11 is a circuit diagram showing still another embodiment of the present invention. This embodiment is similar to the previous embodiment, and corresponding parts are given the same reference numerals. In this embodiment, with respect to a plurality of adjacent heat generating resistors P, the adjacent side thereof is determined as the other heat generating resistor Pb1 and connected to the connection wiring 50a. In this way, N adjacent heating resistors P
The other heating resistor Pb1 is connected to the connection wiring 50 in common.
connected to a. In group G2 consisting of N adjacent heat generating resistors P, similarly to group G1, among each heat generating resistor P, the adjacent side is determined to be the other heat generating resistor Pb2, and the connecting wiring 50b in the diode array element 30b is connected. Connect everything. A diode 58 is connected to one heating resistor Pa of each of the two groups G1 and G2, as in the previous embodiment.

For each diode 58, one type is selected in which the corresponding heating resistor P is connected to different connection wirings 50a and 50b, and the output ends of the diodes 58 are commonly connected and connected to the connection conductor 35. are connected to each other. Further, the output terminal of this diode 58 is connected to each group G1.
, G2, the output ends of the diodes 58 connected to the heat generating resistors P at mutually corresponding positions in the arrangement direction of the heat generating resistors P are sequentially connected in common.

In this embodiment as well, the number of connecting conductors 35 is the number N of heating resistors P in groups G1 and G2, and the number of connecting conductors 35 is equal to the number N of heating resistors P in groups G1 and G2, and the number of connecting conductors 35 is equal to the number N of heating resistors P in groups G1 and G2, and the number of connecting conductors 35 is equal to the number N of heating resistors P in groups G1 and G2, and
The patterns are formed on the insulating substrate 23 in the same manner as in the first embodiment. Therefore, even in such an embodiment, effects similar to those described in the previous embodiment can be achieved.

FIG. 12 is a circuit diagram showing an example of the configuration of a diode array element 30c according to still another embodiment of the present invention. This embodiment is similar to the previous embodiment, and corresponding parts are given the same reference numerals. In this embodiment, among the N heat generating resistors P connected corresponding to one diode array element 30c, one of the two adjacent heat generating resistors P is connected to the other heat generating resistor Pb1 within the diode array element 30c. The diode 58 is connected such that the other heating resistor Pb1 is on the cathode side, and the anode of the diode 58 is connected to the connection wiring 50a.

A diode 58 is connected to the other heating resistor Pb2 of the adjacent heating resistors P as described above, and the anode of this diode 58 is connected to the connection wiring 50b. Such a connection state is repeated for each pair of adjacent heating resistors P. Further, one of the heat generating resistors Pa of the pair of adjacent heat generating resistors P is connected in common within the diode array element 30c, and respectively connected to the connecting conductor 35. Even in such an embodiment, the same effects as those described in the previous embodiment can be achieved.

FIG. 13 is an enlarged plan view of the vicinity of the heating resistor P of still another embodiment of the present invention. This embodiment is similar to the previous embodiments, and corresponding parts are given the same reference numerals. In each of the embodiments described above, one heat generating resistor P is divided into two parts in order to energize the heat generating resistor P in the sub-scanning direction of the thermal head 21, that is, in the vertical direction in FIG. I was connected on 27. In this embodiment, instead of this, each heating resistor P is energized in the main scanning direction, and the individual electrodes 29a,
The substrate end side of 29b is arranged at a position sandwiching the heating resistor P along the main scanning direction. Such a configuration is equivalent to the electrical configuration of the heating resistor P in the electrical circuit diagram of FIG. can be achieved.

In the present invention, the number N of heating resistors P constituting one group is not limited to four as in the above embodiment, and the number M of common electrode lines may also be four or more. It is possible.

FIG. 14 is a plan view showing a modification of the embodiment shown in FIG. In this embodiment, the end portions of the individual electrodes 29a and 29b on the heat generating resistor P side, which are similar to those shown in FIG. placed in contact with each other. Such a configuration example is equivalent to the electrical configuration of the heating resistor P in the electrical circuit diagram of FIG. Can be done.

[0054]

As described above, according to the present invention, the number of control circuit elements can be reduced, and the structure can be simplified and the number of parts can be reduced. Furthermore, when using a plurality of common electrode lines, it is no longer necessary to construct a multilayer wiring structure on the insulating substrate on which the heating resistor is formed, and reliability regarding electrical connections can be improved.

Furthermore, a plurality of common electrode lines to which driving power for driving each heat generating resistor to generate heat is supplied are formed on an insulating substrate and are connected to the heat generating resistor through a rectifying element array. Each of the rectifying element arrays is connected to L switching elements built in the control circuit element via the rectifying elements inside the rectifying element array. Therefore, each common electrode line and the heating resistor are prevented from being formed so as to overlap with any common electrode line, and it is possible to simplify the manufacturing process and improve reliability regarding electrical connection.

[Brief explanation of drawings]

FIG. 1 is a plan view of a thermal head 21 according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along section line X2-X2 in FIG. 1;

FIG. 3 is a plan view of an insulating substrate 23. FIG.

FIG. 4 is an electrical circuit diagram of the thermal head 21.

FIG. 5 is a timing chart illustrating the operation of the thermal head 21.

FIG. 6 is another example of the configuration of the thermal head 21.

7 is a plan view showing still another modification of the thermal head 21. FIG.

FIG. 8 is a plan view of a portion of a thermal head 21a according to another embodiment of the present invention.

FIG. 9 is a circuit diagram of the thermal head 21a.

FIG. 10 is a circuit diagram of another embodiment of the present invention.

FIG. 11 is a circuit diagram of another embodiment of the present invention.

FIG. 12 is a circuit diagram of another embodiment of the present invention.

FIG. 13 is a plan view of another embodiment of the invention.

FIG. 14 is a plan view of another embodiment of the invention.

FIG. 15 is an electrical circuit diagram of a first conventional example.

FIG. 16 is an electric circuit diagram of another conventional example.

FIG. 17 is a perspective view of the thermal head 1a.

[Explanation of symbols]

21, 21a Thermal head 23 Insulating substrate 27 Connection electrode members 28a, 28b, 28c Common electrode line 29 Individual electrodes 30, 30a, 30c Diode array element 33
Drive circuit elements 50, 51 Connection wiring 58 Diode 62 Transistors P, Pa, Pb1, Pb2 Heat generating resistors VH1 to VH
3 Drive voltage

Claims (4)

[Claims] 1. A thermal head in which a plurality of heat generating resistors are arranged on an insulating substrate, in which N pairs of heat generating resistors each having one end electrically connected are arranged,
M common electrode lines less than N are arranged on the insulating substrate, and the other end of one of the pair of heating resistors is connected to one terminal of a rectifying element, and the other end of one of the pair of heating resistors is connected to one terminal of a rectifier. The other end of the heating resistor is connected to the common electrode line, and the other terminal of the rectifying element is connected to L switching elements, which are less than N, built in the control circuit element. thermal head. 2. In a thermal head in which a plurality of heat generating resistors are arranged on an insulating substrate, N pairs of heat generating resistors each having one end electrically connected are arranged, and N heat generating resistors are arranged on the insulating substrate. The other end of one of the pair of heating resistors is connected to one terminal of the rectifying element, and A thermal head characterized in that each end is connected to L switching elements, which are less than N, and which are built in a control circuit element. 3. In a thermal head in which a plurality of heat generating resistors are arranged on an insulating substrate, each of the N heat generating resistors is provided with one electrode and the other electrode, and the M heat generating resistors, which are smaller than N, are arranged on the insulating substrate. A common electrode line is arranged, each of the one electrodes is connected to one terminal of a rectifying element, the other electrode is connected to the common electrode line, and the other terminal of the rectifying element is connected to an N line built in the control circuit element. A thermal head characterized in that the thermal head is connected to L switching elements, each of which is less than L switching elements. 4. In a thermal head in which a plurality of heat generating resistors are arranged on an insulating substrate, each of the N heat generating resistors is provided with one electrode and the other electrode, and the M heat generating resistors, which are smaller than N, are arranged on the insulating substrate. A common electrode line is arranged, each of the one electrodes being connected to one terminal of the rectifying element, and the other electrode being connected to L switching elements, which are less than N, built in the control circuit element. Features a thermal head.