JPH02215550A - Thermal head - Google Patents

Abstract

PURPOSE:To record at high speeds without losing gradation by providing pairs of separate electrodes in a scattering manner in two directions and conducting drivers for supplying power to a heat generating resistance body, onto said band-shaped heat generating resistance body formed on a common band-shaped electroconductive body. CONSTITUTION:A common electrode layer 7, a heat generating resistance layer 8 and an insulative layer 9 are sequentially formed on an insulative substrate 13 in this order. A pair of separate electrode layers 10 are formed after the insulative layer 9 above the heat generating resistance layer 8 is removed. The separate electrode layers 10 are formed in a scattering manner in accordance with the recording density, and connected to a conductive driver 3. The confronting electrode layers 10 are arranged not to be in contact with each other. An anti-abrasion layer 11 which works also for the insulation purpose is formed on the electrode layers 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head used in a thermal printer, and particularly to a thermal head in which heating resistors are arranged in two rows.

[Conventional technology]

Normally, a thermal head consists of one or more rows of tiny heat-generating resistors arranged in a row, and a specific heat-generating resistor selected from among the plurality of resistors is energized to generate heat, causing the thermal paper that comes into contact with it to develop color. , ink is sublimated or melted from an ink film and transferred to recording paper to visualize electrical signals.

In this thermal head, two heating resistors are used compared to the conventional one.
There are thermal heads arranged in rows. Japanese Patent Publication No. 55-934
In No. 72, the heating resistors are arranged in a staggered manner, and the first and second stages are energized alternately to print one line, thereby suppressing the current value of simultaneous energization. In Japanese Patent Application Laid-open No. 51-36074,
The heating resistors are arranged in two rows with two line pitches apart, and the first and second lines are alternately energized while moving at one line pitch in the sub-scanning direction, thereby suppressing the current value of simultaneous energization.

The common electrode of this thermal head is located between two lines, and its width is about one line pitch. However, as the number of heating resistors increases, the resistance value of the common electrode increases. JP-A No. 60-1431175 uses a thermal head in which two heating resistors are arranged in two rows with a common electrode in between, and electricity is applied alternately between the 1st and 2nd lines during 1-line printing to shorten the printing time. are doing. This Japanese Patent Publication No. 60-143975
The issue does not mention the voltage drop due to the resistance value of the common electrode when a large number of heating resistors are arranged.

[Problem M to be solved by the invention] The above prior art does not take into consideration the resistance value of the common electrical conductor of a two-line thermal head in which a large number of heating resistors are arranged, and the two lines of heating resistors are arranged close to each other. In this case, since the width of the common electrode cannot be made large, the resistance value per unit length becomes large. In a 2-line thermal head for a serial printer, the length of the common electrical conductor is short, so the voltage drop due to the total resistance of the common electrical conductor is not a big problem.However, in a 2-line thermal head for a line printer, the common electrical conductor Since the purity of the conductor is long, voltage drop due to the resistance value of the total common electrical conductor becomes a problem. Generally, it is necessary to suppress the total resistance value of the common electrical conductor to about 10 mΩ.

Another problem is that if one heating resistor is energized at the same time,
There is a problem that a large amount of current flows and the power supply capacity becomes large.

In addition, in a two-line head, heating resistors are often arranged at high density, and there is a problem in that transfer failure occurs during high-speed recording. In particular, the transferability of the front part of the recorded dots becomes poor. In other words, the heating resistor has the characteristic of gradually increasing its temperature with respect to the energization time, so that sufficient transfer is not achieved in the initial stage. In some areas, sufficient transfer is not achieved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure and a driving method for a thermal head in which a plurality of heat generating resistors are arranged in two lines in which recording can be performed at high speed without impairing N tonality.

[Means to solve the problem]

The above objects are as follows: 1. In a thermal head in which a plurality of heating resistors are arranged in two lines, a common electric conductor formed in a band shape;
A heating resistor formed in a band shape on this common electric conductor, a pair of individual electrodes disposed discretely and in both directions on this heating resistor, and a heating resistor for energizing the heating resistor. This is achieved by including a current-carrying driver.

2. In a thermal head in which a plurality of heating resistors are arranged in two lines, a common electric conductor formed in a band shape;
Heat generating resistors are formed in two rows in a strip shape on this common electric conductor, individual electrodes are arranged on the heat generating resistors in M numbers on the outside in a direction perpendicular to the generating resistor, and heat generating resistors This is achieved by including an energizing driver for energizing the body.

3. In a thermal head in which a plurality of heating resistors are arranged in two lines, the resistance values of the heating resistors arranged in two lines in one line printing width are made different between the first and second rows, and the recording paper is This is achieved by reducing the resistance value of the column recording the front part of the dots with respect to the feeding direction.

4. In a thermal head in which a plurality of heating resistors are arranged in two rows in a line, the heating resistors are formed in two rows in the form of a band, and the heating resistors are formed discretely on the outer side in the perpendicular direction to the heating resistors. This is achieved by providing a pair of individual electrodes, a current-carrying driver for energizing the heat-generating resistors, and an electrode connected across both rows of heat-generating resistors and led to a common electrical conductor.

5. In the thermal head described in 4 above, this is achieved by bringing all the individual electrodes in a pair to one side of the electrodes that are led to the common electric conductor on both sides so that the resistance value is approximately 1:2. Ru.

The method for driving the thermal head described above is as follows: 1. The heating resistors arranged in a line are divided into two or more parts in the line direction, and the distance traveled in the sub-scanning direction is shifted by the distance divided into two or more parts. The placed thermal head is divided into blocks, and each block is sequentially energized. This allows power consumption to be reduced.

2. The interval between the center lines of the heating resistors in two rows is set as one line printing width, and the heating resistors are energized alternately in two groups in the main scanning direction. The first group and the second group are alternately arranged every other or more times. One group is energized while moving by one line printing width in the sub-scanning direction. This allows power consumption to be reduced.

3. Considering four adjacent heating resistors as one heating resistor,
By controlling two energizing drivers, all four are turned on. Turn on three, turn on two adjacent in the main scanning direction (you can turn on two opposite ones), turn on two on the diagonal, turn on one, turn off all four Select one of the following to print. This allows multi-tone recording.

4. Using a thermal head whose positions are shifted in the line direction between the first and second lines, the individual electrodes arranged discretely and bidirectionally on the heating resistors are used to measure the individual electrodes on the four adjacent heating resistors. , turn on all four, turn on the two on the longer diagonal and turn on the other, turn on the two on the shorter diagonal and turn on the other. Two on the shorter diagonal are turned on (two opposing ones or two adjacent in the main scanning direction may be turned on), two on the longer diagonal are turned on, and one is turned on. Turn off all four or select one of these to print. This allows multi-tone recording.

5. By changing the resistance values of all four adjacent heating resistors and controlling the four energizing drivers,
Performs multi-tone recording.

[Effect]

(1) If the common electrical conductor, heating resistor, and individual electrode are sandwiched in the depth direction, the cross-sectional area of the common electrical conductor can be increased, so that the resistance value of the common electrical conductor can be reduced.

(2) Since the heating resistors can be placed close to each other on the first and second lines, four adjacent heating resistors can be considered as one.
Recording density can be changed. Furthermore, multi-gradation recording is possible by controlling the four heating resistors.

(3) The heating resistors arranged in a line are divided into two or more parts in the line direction, and the thermal heads are arranged offset from each other by a distance that divides the distance traveled in the sub-scanning direction into two or more parts. By sequentially energizing each block, it is possible to eliminate printing deviation in one-division drive.

(4) Power can be reduced by dividing the heating resistors into two groups in the main scanning force direction and printing alternately.

(5) By reducing the resistance value of the heating resistor on the first line of the thermal head with respect to the traveling direction of the recording paper,
Transfer defects at the front of recorded dots can be reduced.

(6) By biasing the heat distribution on the heating resistor,
The transfer characteristics of small dots are improved.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail.

FIG. 1 is a schematic view of a thermal head which is an embodiment of the present invention, and FIG. 2 is an enlarged view of the vicinity of a heating resistor. In these figures, la.

1b is a heating resistor, 2a and 2b are individual electrodes connected to each heating resistor, and 3a and 3b are current drivers.

4 is a common electric conductor, 5 is a driver mounting board, and 6 is a head board. Note that the energizing driver 3 on the driver mounting board 5 and the individual electrodes 2 are connected by pressure contact. Also,
3rd v! i is a diagram showing the internal structure of the thermal head of the present invention, 7 is a common electrode layer, 8 is a heating resistance layer, 9 is an insulating layer, 10 is an individual electrode layer, 11 is a wear-resistant layer, and 12 is a protective layer. , 13 is an insulating substrate.

The common electric conductor 4 must have a sufficiently small resistance value in order to stop receiving current from all the heat generating resistors 1.

Therefore, the common electrode layer 7 has a sufficiently large cross-sectional area with respect to one individual electrode layer 10. As shown in FIG.
A common electrode N7 is formed on the common electrode N7, and a heating resistance layer 8 is formed on this. After forming an insulating layer 9 thereon and removing the insulating layer 9 on the heating resistor layer 8, one individual electrode layer 10 forming an individual electrode layer 10 is formed discretely according to the #J1 density. and connected to the energizing driver 3. The opposing individual electrode layers 10 do not come into contact with each other, and a wear-resistant layer 11 that also serves as insulation is formed thereon. Note that the heating resistance layer 8 may be formed uniformly in the line direction, or may be formed uniformly in the line direction.
They may be divided into two rows and formed uniformly, or a plurality of them may be arranged discretely in two rows.

The energizing driver 3 turns on the internal transistor in response to the print signal, passes current through the heat generating resistor 1, causes the heat generating resistor 1 to generate heat, and the resistance value of the heat generating resistor 1 is determined by the thickness of the heat generating resistor layer 8 and the heat generated. Individual electrode layer 10 in contact with resistive layer 8
Adjust by the area of

FIG. 4, FIG. 5, FIG. 6, and FIG. 7 show modified examples of the above-mentioned thermal head. In FIG. 4, the thermal head has an insulating substrate], 399 partial brace 14. Common electrode layer7. Heat generating resistance layer 8. Insulating layer 922 individual electrodes 10. Wear-resistant layer 11. The protective layer 12 is deposited and formed in the order of 6
The heating resistor M8 is formed in contact with the common electrode layer 7, and the individual electrode layer 10 is formed by removing a portion of the insulating layer 9 to form the heating resistor layer 8.
The zero-part brace layer 14 formed in contact with the heating resistor 1 functions to bulge the heating resistor 1 and improve its contact. In addition,
Since the common electrode layer 7 does not have a sufficient cross-sectional area, the common electric conductor 4 is formed in a strip shape in the line direction apart from the heating resistor 1, and the common electrode layer 7 is connected to this common electric conductor 4 to form a resistor. Decrease the value.

In FIG. 5, the thermal head includes an insulating substrate 13, a common electrode layer 72, a heating resistance layer 8. Insulating layer 9゜Individual electrode layer 10
．． Wear resistance M11. The zero heating resistor M8 formed by depositing in the order of the protective layer 12 is formed in contact with the common electrode layer 7,
The individual electrode layer 10 is.

It is formed by removing a portion of the insulating layer 9 and being in contact with the heating resistance layer 8 . In this thermal head, a part of the insulating substrate 13 is raised instead of the partial brace kI14 in FIG. 4.

In FIG. 6, the thermal head includes an insulating substrate 13, a common electrode layer 7. Insulating layer 91 Individual electrode layer 10, protective layer 122 which also serves as insulation, heating resistor layer 8. The wear layer 11 is deposited and formed in this order. The heating resistance layer 8 includes an insulating layer 9 and a protective layer 12.
are formed in contact with each of the individual electrode layer 10 and the common electrode layer 7 by removing a portion of the electrode layer 7 .

In FIG. 7, the thermal head includes an insulating substrate 13, a partial brace layer 14. Common electrode layer7. Insulating layer 92 Individual electrode layer 10. The protective layer 122, the heating resistance layer 8, and the wear-resistant layer 11 are deposited in this order, and the formed 1 heating resistance value 8 is formed by removing a portion of the insulating layer 9 and the protective layer 12, and forming the individual electrode layer 10 and the common electrode layer 7.
are formed by contacting each other.

Now, a method of driving the thermal head will be explained.

FIG. 8 shows a schematic diagram of a thermal printer. Printing is performed line by line by rotating the platen roller 15 at a constant speed with a drive motor 16, conveying the recording paper 7 and the ink film 18 coated with ink, and sending a print signal from the control circuit 19 to the thermal head 20. ,
Note that the line printing direction of the thermal head 20 is the main scanning direction, and the paper feeding direction is the sub-scanning direction.

FIG. 9 shows a thermal head in which the heating resistors 1 are formed so that the interval between the center lines of two rows of heating resistors 1 is one line printing width, and the heating resistors 1 are placed one dot above the main scanning direction. This diagram schematically shows how printing is performed while the recording paper 17 is moved by one line printing width in the sub-scanning direction while being alternately energized. First, the odd-numbered heating resistors 1 of the thermal head 20 are energized to record recording dots 21 indicated by .

Every other line is recorded in the main scanning direction, but two lines are printed at the same time in the sub-scanning direction.Next, even-numbered heating resistors 1 of the thermal head 20 record recording dots 21 indicated by ■. do. The recording paper 17 moves by one line printing width in the sub-scanning direction for each energization. Note that the recording paper 17 may be moved at a constant speed during printing, and recording may be performed by printing odd numbers and even numbers alternately for each line printing width.

In addition, the heat generating resistor of the thermal head may be divided into several blocks in the line direction and driven in one division.At this time, if you are concerned about vertical streaks due to misalignment of one division, please consider the number of divisions. Accordingly, a thermal head is used in which the position of the heating resistor 1 is shifted for each block as shown in FIG. 10.

In Figure 10, the heating resistor 1 is divided into two blocks.

This shows how recording is performed using thermal heads that are arranged so as to be shifted by a distance obtained by dividing the distance traveled in the sub-scanning direction into two. First, the first block, which is recorded first, is driven first, and after the printing width has moved by one line, the second block is driven. As a result, recording is performed two lines at a time.

In addition to the above, by forming a set of four adjacent heating resistors 1 and moving them in the sub-scanning direction with a two-line printing width while simultaneously driving them, it is possible to perform recording with half the recording density.

According to this embodiment, even if two rows of heating resistors are placed close to each other by one line printing width, the common conductor can be made sufficiently large.
There is no problem with voltage drop, and by dividing the drive as described above, the total current value of simultaneous energization can be suppressed and the power supply capacity can be reduced.

FIG. 11 is a diagram illustrating another driving method.

If four adjacent heating resistors 1 are considered as one heating resistor, printing with six levels of different densities is possible as shown in the figure. That is, the transistors of the current-carrying driver 3 are switched, and all four transistors are turned on, and three transistors are turned on. Two adjacent ones in the main scanning direction are turned on (two opposite ones may be turned on), two diagonally opposite ones are turned on, and one is turned on. Turn off all four. Choose one. There are two patterns for energizing the two, each with a different density.

FIG. 12 shows a thermal head in which individual electrodes 2 formed on a heating resistor 1 and arranged discretely and bidirectionally are shifted in the line direction between the first and second lines. , shows how four adjacent heating resistors are considered as one heating resistor and multi-gradation recording is performed. According to this thermal head, printing with different densities in seven levels is possible as shown in the figure. In other words, the transistors of one current-carrying driver 3 are switched and all four are turned on.
Turn on the two on the longer diagonal and the other, turn on the two on the shorter diagonal and turn on the other, turn on the two on the shorter diagonal (turn on the two on the opposite or the main scanning direction) You can choose to turn on two adjacent ones, turn on two on the longer diagonal, turn one on, or turn all four off.

According to this embodiment, multi-gradation recording is possible by using line thermal heads arranged in two rows with a one-line printing width.

FIG. 13 is a diagram illustrating still another embodiment. This thermal head has two rows of heating resistors 1 formed in a strip shape, a pair of individual electrodes 2 discretely connected to the outside in a vertical direction to the heating resistors 1, and both of the two rows of heating resistors. A common connected across and led to a common electrical conductor 4! t
@ 4 a t 4 b, which is formed by 422, is a common electric conductor 6. When electricity is applied to, for example, the individual electrode 2, the resistors on both sides generate heat, and one dot is recorded.

According to this embodiment, even if two rows of heating resistors are placed close to each other by one line printing width, the common electric conductor can be made sufficiently large, so there is no problem of voltage drop in the common electric conductor.

FIG. 14 shows a modification of the thermal head in FIG. 13. This is formed by forming a pair of individual electrodes 2 of the heating resistor 1 and a pair of individual electrodes 2 which are discretely connected to the outside in the vertical direction to one side of the common electrode 22 which is led to the common electric conductor 4 on both sides. This is a thermal head. When this heating resistor 1 is energized, the power supplied is different between Rs, which has a small resistance value, and R1, which has a large resistance value, so that the heat generation distribution will be biased. Figure 15 shows the surface temperature of Rs*R1 depending on the application time. In Figure 15, 1'' is the surface temperature required to transfer the melting ink. Further, t indicates the applied pulse width.

First, the low resistance side is transferred during the application time ts, and then the high resistance side is also transferred during the application time t1. Therefore, by changing the applied pulse width, the amount of ink transferred can be changed. The configuration of one piece is as follows.

This also applies to alternating lead type one-line thermal heads.

Further, in FIG. 16, a pair of individual electrodes 2 which are discretely connected to the heat generating resistor 1 on the outside in the vertical direction are connected to the heat generating resistor 1 in the line direction of the common electrode 22 led to the common electric conductor 4. Using this thermal head, which shows the appearance of thermal heads formed at different distances, by considering four adjacent heating resistors 1 as one heating resistor, and controlling four switches, multi-gradation can be achieved. Records can be made. In addition, the individual electrodes 2 of the four adjacent heating resistors 1
The positions of all may be different.

According to this embodiment, since the heat distribution of the heating resistor can be changed, multi-gradation recording is possible.

FIG. 17 shows another embodiment. This is done by making the resistance values of the heat generating resistors 1 arranged in two rows in one line printing width different between the first and second rows, so that the front part of the dot is recorded in the row with respect to the direction in which the recording paper 17 is fed. It has a lower resistance value. The resistance value can be reduced by changing the material of the resistor or by widening the width of the individual electrodes 2. Figure 6 shows a thermal head with the first row of individual electrodes widened. When this thermal head is energized, the surface temperature of the heating resistor 1 with respect to the printing time becomes the same as that shown in FIG. 17. That is, the dot with the smaller resistance value reaches the melting point first, and transfer is performed. Therefore, even if the recording paper 17 is continuously fed and high-speed recording is performed, the transfer failure at the front of the dot where recording starts can be improved.

According to this embodiment, there is an effect of improving the transfer characteristics during high-speed recording compared to the conventional method.

[Effects of the Invention] According to the present invention, even if two rows of heating resistors are arranged close to each other, the resistance value of the common electric conductor can be reduced, so that voltage drop in the common electric conductor can be prevented. .

Further, according to the present invention, by considering four adjacent heating resistors as one heating resistor, it is possible to perform multi-gradation recording.

Further, according to the present invention, the transfer characteristics can be improved by making the resistance values of the heating resistors arranged in two rows with one line printing width different between the first row and the second row.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a thermal head according to an embodiment of the present invention, FIG. 2 is an enlarged view of the vicinity of the heating resistor in FIG. 1, and FIG. 3 is a diagram showing the internal structure of the thermal head. Figure 4,
5, 6, and 7 are diagrams showing modified examples of the thermal head shown in FIG. 3, FIG. 8 is a configuration diagram of a thermal printer, and FIG. 9 is a diagram of the thermal head of this embodiment. FIG. 10 is a diagram showing a method of driving a thermal head in which the heating resistor is divided into two blocks and the two blocks are staggered. FIG. , Figure 1 shows how four adjacent heating resistors are considered as one heating resistor and multi-gradation recording is performed.
2 is a diagram showing a modification of FIG. 11, FIG. 13 is a diagram showing a thermal head according to another embodiment of the present invention, and FIG. 14 is a diagram showing a modification of the thermal head in FIG. 13. ,
FIG. 15 is a diagram showing the surface temperature measurement results of the heating resistor in the thermal head of FIG. 14, FIG. 16m is a diagram showing a modification of the thermal head in FIG. 14, and FIG. FIG. 4 is a diagram showing a thermal head in which the resistance values of the first and second rows are different. DESCRIPTION OF SYMBOLS 1... Heating resistor, 2... Individual electrode, 3... Current-carrying driver, 4... Common electric conductor, 5... Driver mounting board, 6... Head board, 7... Common electrode layer, 8
... Heat generating resistance layer, 9 ... Insulating layer, 1o ... Individual electrode layer, 11 ... Wear-resistant layer, 12 ... Protective layer, 13.
...Insulating substrate, 14...Partial brace layer, 15...
Platen roller, 16... Drive motor, 17... Recording paper, 18... Ink film. 19... Control circuit, 20... Thermal head, 21
...Recording dot, 22...Common electrode. Fig. 1 Fig. 1 Fig. 1 Otsu Fig. 4 Fig. 1

Claims (1)

[Scope of Claims] 1. A thermal head in which a plurality of heat generating resistors are arranged in two lines, a common electric conductor formed in a strip shape, and a heat generating resistor formed in a strip shape on the common electric conductor. and,
A thermal device characterized by comprising: a pair of individual electrodes disposed discretely and bidirectionally on the heating resistor; and a switch provided on each individual electrode for energizing the heating resistor. head. 2. In a thermal head in which a plurality of heat generating resistors are arranged in two lines, a common electric conductor formed in a band shape, a heat generating resistor formed in two lines in a band shape on this common electric conductor, and these A pair of individual electrodes are provided on the heating resistor, and a pair of individual electrodes are disposed discretely on the outside in a direction perpendicular to the heating resistor, and a switch is provided on each individual electrode for energizing the heating resistor. Features a thermal head. 3. In a thermal head in which a plurality of heat generating resistors are arranged in two lines in a line shape, the heat generating resistors are formed in two rows in a band shape;
A pair of individual electrodes are connected to the heating resistor in a discrete manner on the outside in the vertical direction, and each individual electrode is provided with
A thermal head comprising: a switch for energizing the heating resistors; and an electrode connected to both of the two rows of heating resistors and led to a common electrical conductor. 4. In claim 1, the spacing between the center lines of the two rows of heating resistors is defined as one line printing width, and two lines are defined in the sub-scanning direction.
A thermal head that moves in line printing width and changes recording density by driving four adjacent heating resistors separately or simultaneously. 5. Claim 1 is characterized in that four adjacent heating resistors are considered as one heating resistor, and multi-gradation recording is performed by controlling four energizing switches. thermal head. 6. In claim 1, the individual electrodes formed on the heating resistor and arranged discretely and bidirectionally are shifted in the line direction between the first line and the second line, and four A thermal head characterized in that multi-gradation recording is performed by controlling four energizing switches by considering adjacent heating resistors as one heating resistor. 7. In claim 1, when the heating resistors arranged in a line are divided into two or more parts in the line direction and energized, the heating resistors arranged in a line are divided into two or more parts in the line direction. A thermal head is divided into two parts, and the distance traveled in the sub-scanning direction is divided into two or more parts, and the thermal head is arranged so as to be shifted by a distance divided into two or more parts. 8. In claim 1, the interval between the center lines of the two rows of heat generating resistors is one line printing width, the heat generating resistors are divided into one or more blocks every other line in the line direction, and one block is set in the sub-scanning direction. A thermal head is characterized in that it prints alternately between adjacent blocks in the main scanning direction while moving in line printing width. 9. In claim 3, a pair of individual electrodes connected to a heat generating resistor in a discrete manner on the outside in a vertical direction are close to one of the electrodes led to a common electric conductor on both sides. A thermal head characterized by being formed with a 10. In claim 3, a pair of individual electrodes connected to the heating resistor in a discrete manner on the outside in a vertical direction are different in the line direction of the electrodes led to a common electric conductor. A thermal head characterized by being formed with a deviated distance. 11. The thermal head according to claim 1, characterized in that the resistance values of the heating resistors arranged in two rows are different between the first row and the second row.