JPH02283462A - Recording head and thermal recorder using the same recording head - Google Patents

Abstract

PURPOSE:To make recording of multi-gradation easy by a method wherein a width of an electrode is made an effective width of a thermal resistor or under at a connection part with the thermal resistor and is made an width of the electrode at the connection part or over for a part apart from the connection part. CONSTITUTION:Electrode widths of parts 12a, 13a at which a heating element 11 is connected with electrodes 12, 13 are narrower than a width of the heating element 11. The electrode width is almost equal to the width of the heating element 11 at parts apart from the connection parts 12a, 13a. Therefore, as applied time of a pulse signal to be applied to the heating element 11 is gradually prolonged, a distribution in temperature in a width direction of the heating element 11 is being varied. Then, ink is transferred to a recording sheet in a temperature area higher than a melting point Tm of the ink of an ink sheet. Manufacturing cost is reduced thereby, and half tone recording can be excellently performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a recording head capable of expressing halftones when recording an image on a recording medium, and a thermal recording device using the recording head. .

[Prior Art] Recording devices such as printers and facsimile machines use multiple dot forming elements provided in a recording head to record information (image signals).
The dot pattern is formed on a recording sheet (a recording medium such as a recording paper or a thin plastic plate) by selectively driving the dots based on the information. The formats of such recording devices include a serial type in which the recording head is not driven in the width direction of the sheet and records on the sheet, a line print type in which a predetermined length of the sheet is recorded in the row direction, and a line print type in which one page is recorded at once. There are page print types that record.

In addition, recording methods include thermal, inkjet, and wire dot methods. Among these, the thermal method is
It can be divided into a thermal transfer method, which uses an ink sheet to transfer ink to plain paper, and a thermal method, which uses a thermal head to heat the thermal paper to develop color.

2. Description of the Related Art Conventionally, a halftone recording method has been employed to express density differences during color recording or image recording using multiple colors such as cyan, magenta, yellow, and black. In such conventional halftone recording, a method based on the principle of binary recording is adopted, and in order to express gradation using the conventional method, multiple dots are treated as one unit, and the number of dots in that unit is Techniques have been used to express halftones in a pseudo manner using an area gradation method such as a dither method, which expresses halftones by the on/off (binary) ratio of dots.

[Problem to be solved by the invention] However, if the above-mentioned area gradation method is adopted, the number of dots required for one pixel increases in order to express many gradations, so the resolution of the image decreases. There is a problem that the amount decreases. In order to obtain, for example, an image with 64 gradations and a resolution of about 6 pixels/mm by this area gradation method, the resolution of the recording head needs to be about 48 dots/mm. To achieve this with a thermal printer, 4
An 8 dot/mm thermal head is required, but
It is extremely difficult to manufacture such a high-density thermal head, and even if it were possible to manufacture it, the number of elements would be enormous, which would require a large-scale drive circuit to drive the thermal head, making it impractical. In other words, there is a limit to the ability to obtain high-quality gradation recording with binary recording, and there has been a need to put into practical use multi-value gradation recording that expresses the size of one dot in multiple gradations by some method. .

Conventionally, in recording by thermal melt transfer using a commonly used thermal head, density changes corresponding to changes in applied energy are as shown in FIG. 11(A). That is, the rate of change in recording density with respect to applied energy is large;
Furthermore, the variation in recording density was large, as shown by the length of the vertical line in the graph, so it was difficult to achieve an intermediate density. In the conventional thermal head shown in FIG. 11(B), the heating element 101 and the electrode 102 are shaped to have the same width, so the distribution of the current flowing through the heating element 101 is almost uniform. Note that 103 indicates the direction in which the current flows. For this reason, the temperature distribution of the heating element 101 is such that the central portion of the heating element 101, where the amount of heat dissipated is relatively small, has a slightly higher temperature. Therefore, by changing the application time of the pulse voltage applied to the electrode 102, the heating element 1°1
Even if the temperature distribution of 111A and 112A (applying time is 111A<112A) is changed as shown in FIG. Whether the temperature will be higher or not depends on the location. Therefore, as shown in FIG. 11(A), the same applied energy is applied to the heating element 10.
Even if the voltage is applied at 1, the recording density will differ due to a slight difference in the position of the heating element. For this reason, in the thermal transfer recording method using a conventional thermal head,
In reality, only binary recording was possible, so improvements were desired.

The present applicant proposed a thermal head capable of multilevel recording in Japanese Patent Laid-Open No. 63-54261. According to this, by making the width of the electrode at the connection point between the electrode and the heating element less than or equal to the recording effective width of the heating element, in one heating element, especially the heating element part near the connection point with the electrode can be concentrated. By causing heat to be generated, it is possible to provide a heat generation distribution.

However, with such a configuration, manufacturing precision is required as the width of the electrode is narrowed, resulting in poor head manufacturing yields and contributing to an increase in the cost of the head.

Further, even with such a configuration, sufficient gradation cannot be obtained when recording on paper with rough smoothness, and it has been desired to realize a thermal head with even better gradation.

The present invention has been made in view of the above-mentioned conventional examples, and includes a recording head that is capable of multilevel recording, easily realizes recording at multiple gradations, and is inexpensive to manufacture, and a thermal recording device using the recording head. The purpose is to provide

[Means for Solving the Problems] In order to achieve the above object, the recording head of the present invention has the following configuration. That is, it includes a plurality of heating resistors arranged in a row and an electrode for supplying electrical energy to each of the plurality of heating resistors, and the width of the electrode is equal to the width of the connecting portion with the heating resistor. The width of the electrode is smaller than the effective width of the heat generating resistor, and the electrode width of a portion further away from the connection portion is greater than or equal to the width of the electrode at the connection portion.

Further, a thermal recording apparatus using the recording head of the present invention that achieves the above object has the following configuration. That is, it includes a plurality of heating resistors arranged in a row and an electrode for supplying electrical energy to each of the plurality of heating resistors, and the width of the electrode is equal to the width of the connecting portion with the heating resistor. manually generating a multivalued image signal with a recording head whose electrode width is equal to or less than the effective width of the heat generating resistor, and whose electrode width at a portion farther from the connection portion is equal to or greater than the electrode width at the connection portion;
gradation determining means for determining the gradation of image data to be recorded by each heating element of the recording head in accordance with the gradation of the image signal; and recording by energizing each heating element of the recording head according to the gradation. and a recording means for recording.

[Operation] With the above configuration, the thermal recording device inputs a multi-value image signal and determines the gradation of image data to be recorded by each heating element of the recording head in accordance with the gradation of the multi-value image signal. do. Then, according to this gradation level, each heating element of the recording head is energized to perform recording.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments described below will be explained using a thermal recording method using a thermal head as an example, but the present invention is not limited to this. For example, an image can be recorded by ejecting an ink liquid using heat. It can also be applied to a recording method that records an image using heat, such as an inkjet recording method.

[Description of Thermal Head (Figs. 1 to 4) Fig. 1 is a diagram showing the shape of one heating element and electrodes of the thermal head 10 of the embodiment, and Fig. 2 is a diagram showing the shape of one heating element and electrode of the thermal head 10 of the embodiment, and Fig. ' is a cross-sectional view showing the cross-sectional shape of '.

In FIG. 1, reference numeral 11 denotes one heating element of the thermal head 1o, and this thermal head 10 includes this heating element 11.
Image recording is performed by selectively energizing these heating elements in accordance with recording data. 12 is a common electrode for supplying power to each heating element; 13 is a signal electrode provided corresponding to each heating element; the voltage level of the electrode is changed in accordance with recorded data; Power supply control is executed.

Next, based on FIG. 2, the heating element 11 and the electrode 12.43 portion of the thermal head 10 of this embodiment will be explained.

A glaze layer 16 as a heat storage portion is formed on the alumina substrate 7. Furthermore, films of the resistance layer 15 and the electrode layer 12 are formed thereon by vacuum evaporation, sputtering, or the like. Then, electrodes 1, 2. ] 3 and heating element 11,
Furthermore, a wear-resistant layer 14 is formed on the soil by sputtering or the like. The portion called heating element 11 here refers to the resistance layer portion between electrode layers 12 and 13.

As is clear from FIG. 1, the heating element 11 and the electrode 12
．． The electrode width of the parts 12a and 13a where 13 is connected is:
The width of the electrode is narrower than the width of the heating element 1, and the electrode width is wide enough to be approximately equal to the width of the heating element 11 at the portions away from the connecting portions 12a and 13a.

FIG. 3(A) is a diagram showing the flow of current when a pulse voltage is applied to the heating element 11 of the thermal head lO shown in FIG. 1 through an electrode 12.13 narrower than the width of the heating element 11. It is.

1/4 In FIG. 3(A), 2o indicates the current flowing through the heating element 11, and the density of the current flowing through the heating element 11 is determined by the connection point between the narrow electrode 12, 13 and the heating element 11. 1
A dog appears near 2a and 13a.

FIG. 3(B) is a diagram showing the temperature distribution near the electrode 12 in the heating element 11 (in the xx' cross section of FIG. 3(A)).

The temperature near this electrode 12 (or electrode 13) is particularly high among the heating elements 11. Then, in order to change the energy applied to the heating element 11, when the application time of the pulse signal applied to the heating element 11 is gradually lengthened, the temperature distribution in the width direction in the xx' cross section of the heating element 11 becomes , curves 42-43-44 in FIG. 3(B)
It changes like this. In FIG. 3(B), T and a indicate the melting point of the ink on the ink sheet, and in a temperature range higher than this, the ink on the ink sheet will be melted and transferred to the recording sheet.

Therefore, the area of the dots to be transferred changes as shown in FIG.
) as shown by 42A, 43A, and 44A.

Further, the width of the electrodes 12, 13 is narrow near the connecting portions 12a, 13a connected to the heat generating element 11, but is approximately the same as the width of the heat generating element 11 elsewhere. For this reason, special precision is not required compared to the heating element of a conventional thermal head, so that there is almost no difference in manufacturing yield. Therefore, a thermal head with good productivity and low cost can be provided.

Using such a thermal head, we measured how the recording density changes by changing the energy applied by the thermal head. The results are shown in FIG.

As a result, the recording density has a slope (rate of change) as shown in the graph shown in Figure 4 with respect to the magnitude of the applied energy.
The variation in concentration becomes smaller as shown by the length of the vertical line in the graph. For this reason, for example, by controlling the time for applying a pulse signal to the thermal head 10 or its voltage value, that is, the applied energy, the pixel density recorded by one heating element can be changed with high accuracy. It becomes possible to express different tones, and the density variations in halftone recording can be made sufficiently small and stable.

[Description of another thermal head (Fig. 5)] Fig. 5 shows the heating element 11 and electrode 12b of a thermal head of another embodiment.
, 13b.

In this heating element 11, a common electrode 12b and a signal electrode 13
The electrode width near the connection point between b and the heating element 11 is narrower than the width of the heating element 11, and at a portion away from the heating element 11, it is approximately the same width as the heating element 11.

Generally, the heat of the heating element 11 is radiated not only into the air but also through the electrodes 12 and 13, which have high thermal conductivity. Therefore, by forming the shape as shown in FIG. 5, the heat dissipation of the heat generating element 11 is performed through the electrodes 12 and 13 which are adjacent to each other at a distance of 1IIIL, so that the heat dissipation of the heat generating element 11 is performed through the electrodes and the heat generating element 11. It is no longer concentrated near the connection point. As a result, the heat dissipation of the heat generating element 11 becomes substantially uniform over the entire element 11, resulting in a uniform distribution that further enhances the heat concentration effect, thereby making it possible to further enhance the heat generation concentration effect.

At this time, the distances between the heating element 11 and the electrodes 12 and 13 are set as follows to prevent contact between the electrode and the heating element 11.
It is necessary to make the length longer than the limit value of head manufacturing accuracy.

Conversely, if the distance is too long, the heat dissipation effect of the electrodes 12, 13 cannot be obtained, and therefore the heat dissipation of the heating element 11 will be concentrated near the connection point with the electrodes. Further, if the distance is too long, the narrow portion of the electrode at the connection portion between the heating element 11 and the electrodes 12, 13 becomes long, resulting in poor manufacturing yield.

The above results are summarized in the table below.

(Left below) As is clear from the table above, the distance is 1! [L is 0.1 μm ~
When a 3 mm thermal head is used and the amount of applied energy is varied, the gradation is good in all cases. There is also no problem with the manufacturing yield of these thermal heads. However, if the distance is less than 01 μm, manufacturing cannot be performed due to manufacturing accuracy, and if it is larger than 3 mm, the narrow portion of the electrode becomes long, resulting in poor manufacturing yield.

[Description of other thermal heads (Figs. 6 to 10)] Fig. 6 shows the heating element 1 of the thermal head 21 of another embodiment.
1 and an enlarged front view showing the shapes of electrodes 12c and 13c.
2'c is a common electrode, and 13c is a signal electrode.

As shown in the figure, the widths of the electrodes 12c and 13c are sufficiently smaller than the width of the heating element 11 at the connecting portions between the heating element 11 and the electrodes 12c and 13c.

Then, at a portion away from the connection point between electrodes 12c and 13c,
Moreover, the electrodes 12c and 13 are located near the periphery of the heating element 11.
c is close to the heating element 11 with a small space left therebetween.

The heat generation temperature distribution when the heat generating element 11 is energized is shown in the seventh figure.
As shown in the figure.

FIG. 7(A) is a diagram showing the current distribution flowing through the heating element 11, and the current density is high near the connection point between the heating element 11 and the electrode, where the width of the electrodes 12'c and 13c is narrow. There is. Furthermore, the electrode 1 that is in contact with the heating element 11
The width of 2c and 13c is narrower, but 12
As shown by x, 12y (13x, 13y), since a part of the electrode is close to the periphery of the heating element 11, the heat at the periphery of the heating element 11 is transferred to the electrodes 12X, 12y.
:Y (13x, 13y) is conducted and heat is radiated. As a result, when the heating element 11 is generating heat, the temperature of the peripheral portion of the heating element 11 is particularly lower than that of other parts.

FIG. 7 CB) shows the electrode 12 of the heating element 11, which has a particularly high temperature.
c (13c) Nearby part (YY' part in Figure 7 (A))
In this figure, the temperature difference between this part and other parts of the heating element is particularly large. Therefore, when the application time of the pulse voltage is gradually lengthened in order to change the applied energy, the temperature distribution in the width direction of the heating element 11 changes as shown by the curve 23→24→25 in FIG. 7(B).

At this time, if the melting point temperature of the ink on the ink sheet is T□, then in a temperature range higher than T, the ink melts and is transferred to the recording paper. Therefore, the area of the transferred dots increases as shown in 23A, 24A, and 25A in FIG. 7(C) according to the change in the temperature distribution in FIG. 7(B). Note that the pulse energization time has a relationship of 23<24<25.

Furthermore, the relationship between the energy applied by the thermal head 21 and the recording density is as in the case of FIG. 4 described above.
The slope corresponds to the applied energy, and the variation in each concentration becomes smaller as shown by the vertical line in the graph.

FIGS. 8 and 9 are diagrams showing the shapes of heating elements and electrodes of a thermal head according to another embodiment.

In the heating element 11 and electrodes 12d, 13d in FIG. 8, in order to improve the heat dissipation effect of the peripheral edge of the heating element 11, the portions of the electrodes 12d, 13d that protrude toward the heating element 11 are moved away from the heating element 11. It becomes wider as time goes on.

FIG. 9 is a diagram showing the shapes of the heating element 11 and electrodes 12e, 13e of a thermal head according to still another embodiment.

Here, the electrodes 12e and 13e are divided into two in the middle and connected to the peripheral edge of the heating element 11. Then, a protrusion 2 of the electrode is placed in the center of the electrode at a position away from these connection parts.
6 (27) is nearby. FIG. 10 shows the temperature distribution when the heating element 11 is energized.

Here, the temperature is highest in the vicinity of the connection between the electrodes 12e and L3e and the heating element 11, where the density of the current flowing through the heating element 11 is highest, and heat generation (transfer) occurs as shown at 28 in FIG. It is the center of In this way, the ninth
According to the heating element shown in the figure, the area 28 that is the center of transfer is 1
Since they are distributed in four parts within one heat generating element, there is an effect that the gradation is increased in a pseudo manner and the resolution is increased.

As explained above, according to the thermal head of this embodiment, the width of the electrode at the connection part between the heating element and the electrode is set to be less than or equal to the width of the heating element, and the width of the electrode at the part away from the connection part is set to the electrode width at the connection part. By doing the above, the yield at the time of manufacturing the head is good, and by controlling the applied energy, gradation can be easily expressed.

Further, according to the thermal head of this embodiment, by bringing a part of the electrode close to the heating element, the heat dissipation of the heating element can be changed to make the temperature of the heating element more uniform.

[Description of thermal transfer recording device (Figs. 12 to 14)] 12th
The figure is a block diagram showing a schematic configuration of a thermal transfer recording apparatus using the thermal head 10 of the embodiment. Here, the case of the thermal head 10 of the first embodiment is shown, but the thermal head of other embodiments is also shown. The same effect can be achieved by using

In FIG. 12, 110 is a plain paper cassette that holds plain paper as a recording sheet, 111 is a sensor that detects the presence or absence of plain paper, and 106 is a conveyor for picking up and transporting plain paper from the cassette 110. It's a motor.

A stepping motor 123 rotates the platen 34 via a speed reduction mechanism (not shown). 131 is a motor for raising/lowering the thermal head 10;
The thermal head 10 is driven by this motor 131.
It is pressed against the platen 34 via the ink sheet 32 and recording paper (down state), or separated from the platen 34 (up state). Also, 139 is ink sheet 3
The rotation of the motor 139 is transmitted to the drive shaft of the take-up roll 140, and the ink sheet 32 is taken up in the direction of the arrow. Further, 141 is a supply roll for the ink sheet 32.

35 is a buffer memory that temporarily holds input image data; 36 is an image data conversion table that converts the image data read out from the buffer memory 35, and is usually composed of a look-up table in a ROM or the like. 37
13 is a head drive pulse control circuit whose details are shown in FIG.

FIG. 14 is a block diagram showing the configuration of the thermal head 10.

In the figure, reference numeral 11 denotes a heating element, and each heating element is created based on the above-described embodiment, and is provided for one line in the width direction of the recording paper. A latch circuit 233 latches one line of recording data, and a shift register 234 sequentially inputs serial recording data (gradation data) 444 in synchronization with a clock signal CLK. The serial data input to the shift register 234 in this way is transferred to the latch signal 2
35, the data is latched by the latch circuit 233 and converted into parallel data. In this way, the recording data corresponding to each heating element is held in the latch circuit 233. and,
The timing and time for voltage application are determined by the strobe signal 5TB445, and the AND circuit 2 with data
The output transistor 231 connected to the terminal 32 is turned on.

As a result, current is applied to the signal electrode 13 of the corresponding heating element 11 from the common electrode 12, and the heating element 11 is driven to generate heat.

Next, referring to FIG. 13, head drive pulse control circuit 3
7 will be explained.

450 is an oscillator that outputs a clock CLK of a predetermined frequency, and 451 is a frequency divider circuit that divides the clock signal CLK and outputs a latch signal 235 every time the number of heating elements in one line of the thermal head 10 is counted, for example. be. 440
is a gradation conversion decoder that corresponds to each pixel of input pixel data and transfers gradation data 444 to each register stage of the shift register 234 in synchronization with the CLK signal. With this, for example, when processing a color image, Y.

A gradation conversion decoder 440 performs gradation conversion for each of M and C colors.

441 is a gradation counter, which counts up every time the latch signal 235 is input, and receives the instruction signal 44 from the CPU 38.
3, for example, when using a sublimation ink sheet, use the mod
64 (6 bits), and when using a fusible ink sheet, mod 16 (4 bits) is used. The gradation conversion decoder 440 compares the counted value from the gradation counter 441 with each manually inputted pixel data, and outputs °゛1'° as the gradation data 444 when the pixel data is larger or equal. , when the pixel data is smaller, it outputs °゛0°゛. The strobe signal generation circuit 442 outputs the strobe signal 5TB445 with a slight delay from the latch signal 235, thereby driving the heating element to perform recording.

FIG. 15 is a diagram showing the driving of the thermal head 1o and the timing of the strobe signal STB in the embodiment.

The thermal head 10 is a line type head, and 70 indicates the recording timing for one line.

Assuming that the image data per pixel input to the gradation conversion decoder 440 is composed of, for example, 6 bits, there can be 64 types of data per pixel.

Therefore, in this case, N of N gradations is 64°. First, gradation data 444 corresponding to the first STB signal B1 for one line of data is transferred to the shift register 234,
It is latched by the latch circuit 233 by the latch signal 235. Next, strobe signal B is output, and the heating element that outputs data "1" is driven by the pulse width of B1. During this heating drive, the next gradation data 444 is input to the shift register 234. When the STB signal 445 falls, the latch circuit 233 is activated by the latch signal 235.
is latched to. In this way, the STB signal is then output on B2. Such an operation is executed 64 times (STB signal -B64), and recording for one line is completed.

That is, the gradation conversion decoder 440 manually inputs the image data,
When the value of the m-th pixel data of the line to be recorded in the image is 20°, the value of the gradation counter 441 is placed in the m-stage of the shift register 234 corresponding to the position of the pixel data. Without reference, data 444 is output a total of 64 times such that the first 20 pieces of data are 1' and the latter 44 (64-20) pieces are 0'.

However, at this time, it goes without saying that data is set in other stages of the shift register 234 in accordance with the gradation level of the corresponding pixel.

At this time, each strobe signal STB is
The pulse width is changed depending on the number of times the TB signal is output. The strobe signal generation circuit 44 executes such pulse width adjustment of the strobe signal STB.
It is 2. As described above, this strobe signal generation circuit 442 manually generates the gradation data 444 corresponding to the type of ink sheet 32 using a corresponding ROM table, etc., and generates the STB signal according to the type of ink sheet 32. The width and period of 445 are adjusted.

FIG. 13 is a flowchart showing the recording process in the thermal transfer recording apparatus of the embodiment, which is stored in the ROM of the CPU 38.

Once the image data is input manually in step S1, the process proceeds to step S2, where the image data is stored in the buffer memory 35. In step S3, the recording paper is picked up from the cassette 110 and conveyed to the recording position, and in step S4, the ink sheet 32 is conveyed so that the desired position of the ink sheet 32 is at the recording position. Next, the process proceeds to step S5, where the motor 131 is driven to lower the thermal head 10.

In step S6, one line of pixel data is read from the buffer memory 35 and output to the head drive pulse control circuit 37 through the conversion table 36. As a result, the 12th
Gradation data 444, latch signal 235, and strobe signal STB are output at the timing shown in the figure. As a result, the thermal head 10 generates heat, and transfer recording is performed on the recording paper. Next, the process advances to step S7, where the recording paper and ink sheet 32 are conveyed by one line, and step S8
Check whether the recording process for one page has been completed. and,
If the recording of one page has not been completed, the process returns to step S6;
The pixel data of the next line is read out from the buffer memory 35, and the above-described recording process is performed again.

In the case of color recording, the recording data of each color is recorded one page at a time, and each time the recording of each color is completed, the colored part of the ink sheet to be recorded next is conveyed to the recording position, and the recording paper is also transferred to the platen. 34, return to the original position, and record in a different color.

By performing this operation for, for example, three colors, Y, M, and C, color recording can be performed on recording paper. Further, the gradation width of the gradation data 444, the pulse width of the strobe signal STB, etc. may be changed depending on the type of ink sheet 32 or recording sheet used.

As explained above, this embodiment has been explained using a thermal recording method using a thermal head as an example, but the present invention is not limited to this. It goes without saying that the present invention can also be applied to a recording method that records an image using heat, such as an inkjet recording method that records images.

As explained above, according to this embodiment, the shape of the electrode is formed in the heating element of the thermal head so that the current density flowing through the heating element is different, so that the heating area can be controlled.
By using a thermal head that can easily express gradation, a thermal transfer recording device with good gradation reproducibility can be realized.

[Effects of the Invention] As explained above, according to the recording head of the present invention, the manufacturing cost is low and the recording density can be reliably changed by changing the applied energy, so that it is suitable for recording halftones. There is.

Further, according to the thermal recording device of the present invention, multivalue recording is possible,
This has the effect of easily realizing multi-gradation recording.

[Brief explanation of drawings]

Fig. 1 is an enlarged front view showing the shape of the heating element and electrode portion of the thermal head of the first embodiment, Fig. 2 is a cross-sectional view taken along line E-E' of the heating element of Fig. 1, and Fig. 3. (A) is a diagram showing the current distribution flowing through the thermal conductor of the first embodiment, and Figure 3 (B) is a diagram showing the temperature distribution with respect to the width direction position in the XX' cross section of Figure 3 (A). , FIG. 3(C) is a diagram showing the thermal transfer area corresponding to the applied energy in the thermal head of the first embodiment, FIG. 4 is a diagram showing the relationship between the recording density and the applied energy in the thermal head of the embodiment, and FIG. FIG. 5 is an enlarged front view showing the shape of the heating element and electrodes of the thermal head of the second embodiment. FIG. 6 is an enlarged front view showing the shape of the heating element and electrodes of the thermal head of the third embodiment. 7(A) is a diagram showing the current distribution of the heating element of the thermal head of the third embodiment, FIG. 7(B) is a diagram showing the temperature distribution in the Y-Y' section of FIG. 7(A), Figures 8 and 9 are enlarged front views showing the shapes of the heating elements and electrodes of the thermal head of other embodiments, and Figure 10 is the same as that of Figure 9. Figure 11 (A) shows the relationship between applied energy and recording density in a conventional thermal head. Figure 11 (B) shows the relationship between electrodes and heating elements in a conventional thermal head. shape,
FIG. 12 is a block diagram showing a schematic configuration of a thermal transfer recording apparatus using the thermal head of the embodiment, and FIG. 13 is a schematic configuration of a head drive pulse control circuit. FIG. 14 is a diagram showing the configuration of the thermal head, FIG. 15 is a diagram showing the timing of signals applied to the thermal head,
FIG. 16 is a flowchart showing the recording process in the thermal transfer recording apparatus of the embodiment. In the figure, 10.21...Thermal head, 11...Heating element, 12.12b, 12c, 12d, 12e...
Common electrodes, 13, 13b, 13c, 13d, 13e...
- Signal electrode, 14... Wear-resistant layer, 15... Resistance layer,
16... Glaze layer (17... Alumina substrate, 32
... Ink sheet, 34 ... Platen roller, 35
... Buffer memory, 36... Image data conversion table, 37... Head drive pulse control circuit, 38...
・CPU, 39...Display section, 106, 123, 131
゜139...Motor, 110...Plain paper cassette,
235... Latch signal, 440... Gradation conversion decoder, 442... Strobe signal generation circuit, 444...
- Gradation data, 445... STB signal.

Claims (4)

[Claims] (1) A plurality of heating resistors arranged in a row and an electrode for supplying electrical energy to each of the plurality of heating resistors, the width of the electrode being the width of the connection part with the heating resistor. The recording head is characterized in that the effective width of the heat generating resistor is less than or equal to the effective width of the heating resistor, and the electrode width of a portion farther from the connection portion is greater than or equal to the electrode width at the connection portion. (2) The distance from the connection portion to the portion where the width of the electrode is wider than the width of the electrode at the connection portion is 0.1 μm.
Claim 1, characterized in that the diameter is in the range of m to 3 mm.
Recording head described in section. (3) A plurality of heating resistors arranged in a row, and an electrode for supplying electrical energy to each of the plurality of heating resistors, the width of the electrode being the width of the connection part with the heating resistor. The width of the electrode is equal to or less than the effective width of the heating resistor, and the electrode width at a portion farther from the connecting portion is greater than or equal to the electrode width at the connecting portion, so that a part of the electrode is electrically connected to the heating resistor. A recording head characterized in that the recording heads are adjacent to each other in an insulated state. (4) A plurality of heat generating resistors arranged in a row and an electrode for supplying electrical energy to each of the plurality of heat generating resistors, the width of the electrode being the width of the connection portion with the heat generating resistor. a recording head in which the effective width of the heating resistor is less than or equal to the effective width of the heating resistor, and the electrode width of a portion farther from the connection portion is greater than or equal to the electrode width at the connection portion; gradation determining means for determining the gradation of image data to be recorded by each heating element of the recording head in accordance with the gradation of the recording head; and recording means for recording by energizing each heating element of the recording head according to the gradation. A thermal recording device comprising: