JPS61224779A - Thermal recorder - Google Patents

Abstract

PURPOSE:To obtain a recording picture with high quality by energizing and printing a heating resistance element away from at least one heating resistance element out of the heating resistance elements in the main scanning direction and thereafter, energizing and printing the heating resistance element in which the printing remains. CONSTITUTION:First, when the picture data are supplied from external equip ment 10, the data are accumulated in a buffer memory 11 once, and supplied to a thermal head driving circuit 13. The picture data supplied to the thermal head driving circuit 13 are supplied to a data mask part 131. To the data mask part 131, the least significant bit output of a bit number counter 132 to count the clock synchronizing with the input data or the clock to read the data from the buffer memory 11 and the external equipment 10 bit by bit, and the least significant bit output of the printing number of times counter 133 to count the number of times of the printing are supplied. At the time of the first print ing, the odd number data only are outputted as they are, and at the time of the second printing, the even number data are kept as they are, and the data, in which the odd number data go to be all 0, are outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal recording device that performs high-quality image recording.

[Technical background of the invention and its problems]

Conventionally, so-called non-impact printing technologies for recording images on plain paper include thermal recording, inkjet recording, electrophotographic recording, etc. Among these, thermal recording is particularly useful because it makes the equipment maintenance-free and easy to operate. It has been put to practical use in word processor printers, multi-color printers, etc., as it can simplify the structure, simplify the configuration, and provide color.

By the way, with the recent increase in the level of information content in such thermal recording apparatuses, it is increasingly desired to realize multi-gradation recording and full-color recording.

Therefore, conventional methods such as a sublimation type thermal recording method and a heat-adhesive type thermal recording method have been considered. However, although the former method can express gradations in an analog manner, it has the drawbacks of slow recording speed and poor durability of printed images. The latter also has excellent recording speed and stability of printed images, but since the transfer is binary, this type generally uses area modulation methods such as dithering to obtain gradation recording, so matrix size must be increased, making it impossible to simultaneously achieve multiple gradations and high definition. To solve this problem, an ink ribbon with two layers of ink of different densities is used, and a method of obtaining multiple gradations by combining pixel dots of different densities and pixel arrangement (Japanese Patent Application Laid-open No. 1983-1989-1)
193377), a method of obtaining multiple gradations by forming a dither matrix by sequentially overlapping ink from low density ink to high density ink using an ink ribbon serially coated with inks of different densities (4I' Kaisho 59-5576
No. 8) has been proposed, but even with this method, the selective transfer of ink is unstable, which not only causes deterioration of image quality, but also has the drawback that the recording time is delayed by the number of required density levels of ink.

On the other hand, in recent thermal recording devices, there is a demand for higher image resolution and faster printing speed, and for this reason, the thermal heads used in such devices are mounted with high density and the energization of these heads is performed at high speed. I try to do it.

However, in this case, heat accumulation in the heat generating element of the head becomes a problem, and this heat accumulation may cause image formation.

That is, - for example, 2 as shown in Figure 10(a).
When trying to print a value pattern using thermal heads that are arranged in high density in the main scanning direction, the white part will collapse due to heat accumulation, resulting in the recorded image shown in Figure 10 (b). There was a risk.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermal recording device that can suppress the influence of heat accumulation in a thermal head and obtain high-quality recorded images.

[Summary of the invention]

The thermal recording device according to the present invention includes at least one heating resistor among the heating resistors in the main scanning direction of the thermal head.
By energizing the individual parts to print, and then energizing the heating resistor corresponding to the part where the print is left and printing, the diffusion of heat generated by each heating resistor can be minimized. ing.

〔Effect of the invention〕

According to this invention, heat can be generated quickly in the heating resistor of the thermal head, so that heat accumulation can be significantly suppressed. As a result, heads can be mounted at high density for high resolution, and even when driven at high speeds, the effects of heat accumulation can be reduced, and high-quality recorded images can be obtained. Furthermore, since the influence of heat accumulation can be reduced, the heat of the heat generating resistor of the head can be controlled with high precision, and high quality multi-gradation recording can also be obtained.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

By the way, first of all, to briefly explain the concept of this embodiment, when printing the binary pattern shown in FIG. I have to. (C) is measured using an example in which the entire thermal head is divided into two blocks.
Two printing operations are performed to print the pattern shown in FIG. 1(a). That is, the pattern shown in FIG. 1 (1) is obtained by printing fa1 (b) in the first printing and printing (c) in the second printing. In this way, printing is continuous in the sub-scanning direction, but since printing on both sides of the main scanning direction is not performed simultaneously, the heat generated by energization can be quickly diffused in the main scanning direction. , heat accumulation can be suppressed.

Next, based on this idea, an example will be described.

First, FIG. 2 shows a schematic diagram of the main circuit of the same embodiment.

In the figure, reference numeral 10 denotes an external device that supplies image data, and a buffer memory 12 having an address controller 11 is connected to this external device IO. A thermal head drive circuit 13 is connected to this buffer memory 12. This drive circuit 13 includes a data mask section 131, a bit number counter 132, a printing number counter 33, and a thermal control section 1.
34 and a thermal head interface section 135.

A thermal head 14 is connected to such a thermal head drive circuit 13.

In such a configuration, when image data as shown in FIG. 1(a) is first supplied from the external device 10, this data is temporarily stored in the buffer memory 12 and supplied to the thermal head drive circuit 13.

At this time, the data written to the address specified by the address controller 11 is supplied to the thermal head drive circuit 13. This data consists of binary serial data.

In this case, the data supplied to the thermal head drive circuit 13 may be directly supplied from the external device 10.

The image data supplied to the thermal head drive circuit 13 is given to a data mask section 131. This data mask section 131 is for converting the input image data into data as shown in FIG. 1 Φ) or (C). The output of the least significant bit of a bit number counter 132 that counts the clock that reads out data bit by bit from the memory 12 and external device 10, and the output of the least significant bit of a printing number counter 133 that counts the number of prints are supplied. There is. Now, to explain the data masking section 131 in more detail, as shown in FIG. supplied to Then, the input image data is output from the AND gate 131a only when the least significant bit of the bit number counter 132 is 101, and the input image data is output from the AND gate 131b.
The input image data is output only when the lowest value of is "1". Further, the output signals of these gates 131m and 131b are supplied to the input terminals of the data selector 131C and B. Here, the data selector 131C outputs an adult power signal when the SEL signal is 10 m,
@1", the B input signal is output. Therefore, if the least significant bit of the printing number counter 133 is supplied to the SKI of the data selector 131C, input terminal lζ, it will be supplied to the A input during the first printing. In other words, only the odd-numbered data is output as is, all the even-numbered data are @0", and the second Conversely, when printing, the data selector 131C outputs data in which all the odd-numbered data are O while the even-numbered data remain unchanged.

In this case, the bit number counter 132 counts the CLK signal synchronized with the serial data and is reset for each line by the LINE8YNC signal iζ indicating the start or end of one line, and the printing number counter 133 counts the CLK signal synchronized with the serial data. It counts the signals and is reset by the PRNEND signal indicating that printing of one sheet or printing of one color has ended. Further, when one image is to be printed by two printings as described above, a 1-bit flip-flop may be used as the bit number counter 132 and the printing number counter 133.

As a result, from the data mask section 131, as shown in FIG. 1(b) (C
) pattern data will be output sequentially,
These data are applied to the thermal head 14 via the thermal control section 134 and the thermal head interface section 135, and printing is performed. Here, the thermal control unit 134 is for controlling the pulses applied to each heating resistor of the thermal head 14 in a heat storage state, and stores what kind of data has been printed in the past on the heating resistor that is currently being printed. Then, from this data, the width of the energizing pulse to the heating resistor of interest is determined. The specific configuration of this device is a line memory for storing past several lines of image data supplied to each heating resistor;
Past data for the heat generating resistor of interest outputted from this line memory and inputted current line data are used as address inputs, and pulse width data corresponding to these data is outputted. The ROM used here has a capacity of about 8 bytes and stores past data of about 12 bits. In addition, the thermal controller interface section 135 has a data input method that differs depending on the configuration of the thermal head 14.
The image data sent sequentially from 4 to thermal head 1
This is for rearranging it to match 4.

On the other hand, as the thermal head 14, a direct drive (DD) W type, that is, a type in which one driver drives one heat generating resistor, may be used; Since the number of heating resistors to be used is half of the total, a diode matrix (DM) type, that is, one driver connected to a plurality of heating resistors may be used.

Therefore, the output corresponding to the 11th iffl pattern data given to the thermal head 14 from the thermal head drive circuit 13 causes the 1B! ! The printing shown in I(b) is performed, and then the printing shown in FIG. 1(C) is performed by outputting according to the second pattern data.

In this case, printing l by such a thermal head 14
The movements of the recording paper and the ink ribbon relative to this are as follows.

FIG. 4 is for explaining such movement. In this case, the thermal head 14 has a resolution of 12 dots/w in the width of A4 paper.
(2560 bits/line), the recording paper 15 is A4 width cut paper or roll paper, and the ink pump 16 is A4 width roll type. First, FIG. 4(a) shows the state just before printing starts, and the thermal head 14 is in a state where the recording paper 15 is
The ink ribbon 16 is set at the printing start position.
and is pressed against the recording paper 15. FIG. 4(b) shows a state in which the first printing is being performed. At this time, the ink ribbon 16 and the recording paper 15 move in the direction of the arrow shown in the figure while being pressed against the thermal head 14 to print the pattern. The printing pattern at this time is a ze turn with one bit spaced apart in the main scanning direction as shown in FIG. Then, at the end of this printing, the recording paper 15 and the ink ribbon 16 are separated.

Next, FIG. 4(e) is a diagram at the time when the first printing is completed. For normal printing, at this point the thermal head 1
4, the pressurized state of the recording paper 15 and the ink ribbon 16 is released and the recording paper 15 is ejected to the outside, but in this embodiment, only half of the printing has been completed, so it is ejected at this point. The first printing is completed without any pressure contact. Here, the reason why the pressure contact state is not released is to prevent the positional relationship of the recording paper 15 and the ink ribbon 16 from changing with respect to the thermal head 14.

When the first printing is completed, the recording paper 15 and the ink ribbon 16 are returned in the direction of the arrow shown in the figure while remaining in pressure contact with the thermal head 14, as shown in FIG. 4(d).
), it is reset to the exact same position as when printing started. And as shown in FIG. 4(f), FIG. 4(b)
The second printing is performed in the same manner as above. At this time, the pattern shown in FIG. 1(C) is printed. FIG. 4(g) is a diagram at the time when the second printing is completed, and thereby the printing of the pattern shown in FIG. 1(a) is completed.

In this state, the pressure between the thermal head 14, the recording paper 15, and the ink ribbon 16 is released, the recording paper 15 is ejected to the outside, and the ink ribbon 16 is wound up by a predetermined amount to prepare for the next printing. Ru.

Therefore, by doing this, printing will be continuous in the sub-scanning direction, but since printing on both sides is always paused in the main scanning direction, the heat generated by energization can be quickly diffused in the main scanning direction. It is possible to suppress heat accumulation. As a result, heads can be mounted at high density for high resolution, and even when driven at high speeds, the influence of heat accumulation can be reduced and high quality recorded images can be obtained.

In addition, since the pattern is continuous only in the sub-scanning direction, it is only necessary to pay attention to the sub-scanning direction when performing thermal control for heat storage, which makes it easier to prevent heat storage and damage. The energizing pulse width can be controlled with high accuracy, and high-quality multi-gradation recording can also be obtained by using multi-value data.

By the way, in such embodiments, since printing is required a plurality of times to print one image, it tends to take a long time to complete printing of one sheet. However, as described above, this printer does not accumulate heat in the main scanning direction, so even if a considerably larger current is passed than in a normal printing operation, it is not affected by heat accumulation. From this, Figure 1(b)
When printing in two parts as shown in (C), for example, the printing time can be reduced by increasing the voltage applied to the thermal head and reducing the current pulse width to 1/2 of the normal operation.

Further, in this embodiment, as explained in FIG. 4(d), the recording paper 15 and the ink ribbon 16 are returned to the state at the start of printing without releasing the pressure contact when the first printing is completed. However, at this time, the recording paper 15 and the ink ribbon 16
Since there is a slight gap between the two, it is impossible to completely return them to their original positions without creating a gap between the two. This is because the ink ribbon 16 is peeled off from the paper 15 during the first printing as shown in FIG. 4(b).

. Therefore, by not performing the peeling operation of the ink ribbon 16 until all the operations are completed, the positional deviation between the recording paper 15 and the ink ribbon 16 can be eliminated. In other words, in the case of two-time printing as shown in Figure 4, the first printing (Figure 4)
In the state b), the paper 15 and the ink ribbon 16 are not peeled off, and the peeling is not performed until the second printing in the state shown in FIG. 4(f).

In this way, misalignment between the recording paper 15 and the ink ribbon 16 can be prevented.

Incidentally, in the above-mentioned embodiment, one page is printed by two printing operations, but it is possible to print one page by performing n printing operations and (In-
1) It is also possible to print one page by reversing the paper twice. Moreover, although monochrome recording using a monochrome ink ribbon has been described above, the present invention is also applicable to color recording. A color image is obtained by using a colored ink ribbon having a length of A4 paper and transferring the same number of colors. That is, by repeating the operation described in FIG. 4 three times in the case of a three-color ribbon, and four times in the case of a four-color ribbon, a color image can be recorded.

Next iζ, FIGS. 5(a) to 5(g) show other embodiments of this invention.

In this case, as shown in FIG. 4(d) above, when the paper and ink ribbon are returned to their original positions after the first printing, misalignment may occur between the thermal head and the ink ribbon. If such a positional shift occurs, a portion that has been printed once will be printed in a blank state, and no pixel may be formed even when printing is performed. Therefore, this other embodiment was realized based on the idea that an ink ribbon that has been used once should not be used again. That is, the first printing and the second printing lζ are the same as shown in Fig. 4, but the ink ribbon 16 is returned to the position and the used part is rolled up and the second printing is done with new ink. Printing is performed using a ribbon 16.

In this way, the problem of misalignment between the thermal head 14 and the ink ribbon 6 can also be solved.

Next, FIGS. 6(a) to 6(e) show still another embodiment of the present invention.

In this case, in the printing described in FIG. 4, since the recording paper is once returned to its original position between the first and second printing, the printing time per sheet tends to increase due to this time ζζ.

This means that when an image is divided into 3 or 40%, the number of times the paper must be reversed increases, and it takes longer to print one sheet.

Therefore, in this other embodiment, the first printing is carried out in the same manner as shown in FIG. 4, but the second printing is carried out by using the reverse direction of the paper. Rub the toothpick. This saves wasted time spent reversing the paper. In order to actually obtain such an operation, it is necessary that the address controller 11 described in FIG. 2 be able to access the memory from the opposite direction as well. That is, for example, if image data as shown in FIG. 7 is written in the memory 12, the address controller 11 first accesses the addresses of the memory 12 in the order shown in FIG. 7(a) for the first printing. However, in the case of the second printing, the addresses may be accessed in the order shown in FIG.

Next, FIG. 8 shows still another embodiment of the present invention.

This device divides the required number of pixels in the main scanning direction between a plurality of thermal heads, thereby making it possible to achieve high resolution and at the same time eliminate the effects of heat accumulation I. The thermal head used in this case has two heat generating resistors that share the required number of pixels.As shown in FIG. The number of IA's corresponding to the required number of pixels are arranged one by one, and these heating resistors 22 are connected to the drive IC 24 via lead electrodes 23.

Two such thermal heads 201 and 202 are arranged in parallel as shown in FIG.
5, one thermal head 201 prints a pixel row indicated by the reference numeral 27, and the other thermal head 202 ζ 1 in the main scanning direction.
A row of pixel points indicated by reference numeral 28 shifted by a pixel is printed.

In this case, one thermal head 201 prints a pixel row 27, and then the ink ribbon 25 and the recording paper 26 move in the direction of the arrow shown in the figure, and the pixel row 27 is moved to the position of the other thermal head 202. Thermal head 20 when reached
If the 21-trowel pixel row 2B is printed, the blank area between the pixel rows 27 will be printed, and one line of printing will be possible.

Therefore, in this way, it is possible to increase the resolution of the thermal head, and at the same time, the heat generated by each heating resistor can be quickly diffused to the surroundings, so that heat accumulation can be greatly suppressed. Furthermore, since the packaging density of the thermal head drive IC is reduced, heat accumulation by the drive IC can also be reduced. Since the influence of heat accumulation can be reduced in this way, heat control by the heating resistor can be performed with high precision, and good gradation recording can also be obtained.

This invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications without changing the gist.

For example, although a thermal transfer type was described above, other types such as a color development type can also be applied.

[Brief explanation of drawings]

Figures 1(a), (b), and (C) are diagrams for explaining the concept of an embodiment of the present invention, Figure 2 is a schematic configuration diagram showing the main circuit of the embodiment, and Figure 3 is the same. A schematic configuration diagram showing the data mask section used in the main circuit, FIG.
is a schematic configuration diagram for explaining the same embodiment, and FIG.
) to (g) are schematic configuration diagrams illustrating other embodiments of the present invention, FIGS. FIGS. 8 and 9 are schematic configuration diagrams for explaining still other embodiments of the present invention, and FIGS. 10(a) and 10(b) are for explaining a conventional thermal recording device. This is a diagram for

Claims (3)

[Claims] (1) Out of the heat generating resistors in the main scanning direction of the thermal head, at least one heat generating resistor away is energized and printing is performed, and then the heat generating resistors corresponding to the portions where printing is left are energized and printing is performed. A thermal recording device characterized by: (2) The thermal recording device according to claim 1, wherein the printing operation is repeated n times along with (n-1) times of paper reversing operations. (3) The thermal head has heating resistors separated by at least one heating resistor, 1/m of the required number of pixels in the main scanning direction.
The thermal recording device according to claim 1, characterized in that the thermal recording device is a combination of a plurality of individual devices.