JPS625771A - Picture recorder - Google Patents

Abstract

PURPOSE:To obtain a recording picture of good quality at a boundary portion in a recording area by editing a picture information at an overlapping area to the picture information necessary for the recording picture to keep its continu ity and giving it to a recording head. CONSTITUTION:Assuming that the width of an exothermic element row of a thermal head is W1, an area shown in oblique line is the area obtained by a recording scanning and the second recording scanning area is overlapped by W2 on the first recording area. Each of the picture information S1 and S2 at the overlapped area of a line buffer 34 in a picture recording and editing circuit is multiplied by prescribed factors K1 and K2 at each of multipliers 35 and 36 and with editing them, the picture information S1' and S2' are generated and they are given to and stored at a line buffer 37 along with a picture information S0. The factors K1 and K2 are set at the values so that the picture information necessary for the recording picture to keep its continuity can be obtained. The thermal head is driven based upon the picture information stored at the line buffer 37.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image recording device used in printers, copying machines, and the like.

[Technical background of the invention and its problems]

Conventionally, printers, copying machines, and the like have been known as devices for obtaining hard copies, and the image recording devices used in these devices are broadly classified into serial types and line types depending on the number of recording elements in their recording heads. Here, the serial type uses a so-called short recording head with a relatively small number of recording elements to perform recording in a continuous two-dimensional area by multiple recording scans, while the intie type uses a so-called short recording head with a relatively small number of recording elements. A long print head is used to perform printing over a wide area by performing -times of print scanning.

Incidentally, recently, thermal transfer printers using a short or long thermal head as a recording head have been widely used as a part of such serial type or line type printers. In other words, a printer using a board brings the ink film coated on a thermal head and support material into close contact with the recording paper, and heat from the thermal head is supplied from the support material side of the film to melt or sublimate the ink and transfer it onto the recording paper. Then, a desired recorded image can be obtained.

FIG. 8 is for explaining such a thermal transfer printer in more detail, and shows a so-called serial type thermal transfer printer using a short head.

In the figure, l denotes a thermal head in which 24 heating elements are arranged in vertical columns. This thermal head 1 is disposed on a recording paper 3 via an ink film 2 which is a polyethylene film coated with heat-melting ink. Here, the ink film 2 is stored in a cassette 4. The cassette 4 and the thermal head 1 are mounted on a carriage 5, and are movable in the width direction of the recording paper 3 along guide shafts 7 and 8 by a timing belt 6. On the other hand, the recording paper 3 is wound around a platen 9, and is rotated by a predetermined angle in the direction of the arrow shown in the figure in synchronization with the movement of the carriage 5.

In such a configuration, in order to create a recorded image on the recording paper 3, the heating element of the thermal head 1 is selectively driven to melt the ink on the ink film 2 and transfer it onto the recording paper 3, and the carriage 5 is moved onto the shaft 7. .8 to the right and performs the first recording scan. In this case, the ink film 2 is sequentially supplied with new ink surfaces in conjunction with the movement of the carriage 5. When the recording paper 3 moves to the right end of the recording paper 3, the platen 9 is rotated by a predetermined angle in the direction of the arrow shown in the figure in synchronization with this, and the recording paper 3 is conveyed by a predetermined amount.In this case, the recording paper 3
The amount of conveyance is set to correspond to the width of the heating element array of the thermal head 1, that is, the recording scanning width. From this state, a second recording scan is performed in the same manner as described above, and by repeating these operations in the same manner, a desired recorded image can be obtained on the recording paper 3.

By the way, the recorded images obtained in this way may overlap due to the mechanical precision of the recording paper conveyance system, carriage drive system, etc. or the elongation, distortion, or misalignment of the recording paper 3, or that adjacent recording areas may partially overlap. Alternatively, a gap may occur, and the continuity of the recorded image in this area may be lost, resulting in distortion.

However, in order to obtain an image with extremely high mechanical precision that does not cause such image distortion, an expensive and precise mechanism is required, and it cannot be used as an output terminal for commonly used personal computers and word processors. was difficult to put into practical use.

Further, even if complete continuity of the boundary portions of the recording areas described above could be achieved with mechanical precision, the following problems still exist. First, in the thermal head of such a thermal transfer printer, the distribution of resistance values of each heating element is as shown in FIG. 9, for example, and there is considerable variation. For this reason, even if equal currents are applied to these heating elements, the amount of heat generated by each heating element is different, and in particular, the amount of heat generated at the top and bottom of the row of heating elements does not exactly match.

This causes a difference in recording density. Also, it is difficult to maintain uniform contact between the thermal head, ink film, and recording paper over the entire surface, and if these contacts are not maintained uniformly, the amount of heat transferred from the thermal head to the ink will vary, causing problems. The upper and lower parts of the rethermal head do not match accurately, resulting in a difference in recording density.

As a result, high-density and low-density recorded images are adjacent to each other at the boundary between adjacent recording areas, resulting in a disadvantage that the difference in density at this boundary becomes quite noticeable.

On the other hand, line-type thermal transfer printers using long heads are used in high-speed recording copying machines, facsimile machines, and the like. In this case, the wider the recording width, the longer the recording head is required, but if a long head is obtained by forming a large number of heating elements on the same base material, the manufacturing yield will decrease and it will be difficult to obtain a high-quality head. do not have. For this reason, conventionally, a plurality of short thermal heads are arranged dimensionally to obtain a long head. However, in this case, as shown in FIG. 10, the thermal head 11 is
, 11, the pitch between the heat generating elements 12 becomes P, which is larger than the pitch P, so there is a risk that the recorded image at such a connection part will be discontinuous and distorted. In addition, in FIG. 10, 13 indicates a common electrode, and 14 indicates a lead electrode.

Therefore, some devices have conventionally arranged short thermal heads in a staggered manner to eliminate the above-mentioned disadvantages. However, even if this is done, each short thermal head has a distribution of tx resistance values as described above, and since the average resistance values are different, density differences occur in the boundary recording areas of each short thermal head due to differences in heat generation. Furthermore, there is a risk that image distortion will be noticeable at each connection portion due to the accuracy of arrangement of each short thermal head.

As described above, in the case of a conventional serial type that performs multiple recording scans, image distortion tends to occur at the boundary between each recording area, and that of a type in which short heads are arranged one-dimensionally or in a staggered manner tends to cause image distortion. Image distortion is likely to occur in the connection area of each short head, but image quality deterioration due to these image distortions is more noticeable in image recording than in character recording, and is especially noticeable for human vision in high-definition image recording. There was also the drawback that these image distortions appeared as changes in hue in color recording in which inks of multiple colors were overlaid.

[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 an image recording device that can reduce the distortion of recorded images at the boundaries of recording areas due to recording scanning of the recording head, and can obtain high-quality recorded images. shall be.

[Summary of the invention]

The image recording apparatus according to the present invention has a recording head that performs recording scanning so that a part of the recording area overlaps.
A high-quality recorded image can be obtained in the Sakai area of the recording area by editing and providing the image information of the overlap area to the image information necessary to maintain the continuity of the recorded image in the overlap area obtained by the recording scan. I'm trying to be able to do that.

[Effects of the Invention] According to the present invention, a part of the recording areas due to the recording scan of the recording head overlaps, and since it is possible to maintain the continuity of the recorded image in this overlap area, it is possible to maintain the continuity of the recorded image in the overlapped area. It is possible to significantly reduce image distortion and obtain high-quality recorded images. This is particularly effective in recording high-definition images that express gradations.

[Embodiments of the invention]

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

FIG. 1 shows an example in which the present invention is applied to a serial type thermal transfer plink. In FIG. 1, reference numeral 21 denotes a thermal head in which 64 heating elements are arranged vertically. Such a thermal head 21 is arranged on a recording paper 23 with an ink film 22 interposed therebetween. Here, the ink film 22 is a support material coated with heat-melting ink, and is housed in a cassette 24.

A flat platen 25 having a width slightly wider than the heating element array of the thermal head 21 is arranged on the back of the recording paper 23. The reason why the flat platen 25 is used here is to stabilize the contact between the thermal head 21, the ink film 22, and the recording paper 23 because the thermal head 21 has a large number of heating elements (64) and the recording scanning width is wide. be.

A cassette 24 containing a thermal head 21 and an ink film 22 is mounted on a carriage 26.

This carriage 26 is fixed to a timing belt 27, and two guide shafts 28 are provided in parallel by driving the timing belt 27 by a drive source (not shown).
, 29 in the width direction of the recording paper 23. Further, the recording paper 23 is held by two sets of rollers 30, 3.
1, 32, and 33, and is conveyed upward by a predetermined amount by driving a roller 31 by a drive source (not shown).

In this case, the amount of conveyance of the recording paper 23 is set to be slightly smaller than the paddle of the heating element array of the second thermal head, that is, the recording scanning width, for example, an amount smaller by about 8 to 10 heating elements.

In the thermal transfer precipiter configured in this way, when recording on the recording paper 23, the carriage 26 is first positioned at the left end of the recording paper 23 (hereinafter this position will be referred to as the home position), and from this state the carriage 26 is moved to the shirt IJ position. -28,2
Thermal head 21ζ while moving to the right along 9I
Recording is performed on the trowel recording paper 23. The driving or recording principle of the thermal head 21 in this case is the same as that of a conventional thermal transfer printer, and a description thereof will be omitted here.

Figure 2 (a) fbl is a thermal head 21 like this.
This figure is for explaining the recording scan in the figure (al shows the state in the middle of the first recording scan).

That is, in the same figure (al), assuming that the width of the heating element array of the thermal head 21 is W, the shaded area is the area obtained from the first recording scan, and shows the state in which the recording scan is progressing in the direction of the arrow in the figure. In this state, recording scan is performed on recording paper 2.
3, the drive of the thermal head 21 is stopped and the carriage 26 is returned to its home position. At the same time, the roller 31 is driven and the recording paper 23 is conveyed upward by a predetermined amount. In this case, the conveyance amount is smaller than the width W of the heating element array of the thermal head 21, so the second recording scan area is only W, as shown in Figure 2 (bl), than the first recording area. so that they overlap
In this state, a second recording scan is performed, and by repeating the same reciprocating operation, a desired recorded image is formed on the recording paper 23.

In this case, the recorded image information of the overlapped portion of the recording area obtained every recording scan of the thermal head 21 is created by the image information editing circuit shown in FIG. In FIG. 3, reference numeral 34 denotes a line buffer, in which the recorded image information of the recording area obtained from -times of recording scan I is stored as gradation image information represented by 8 bits per recording pixel.

Here, the image information S, , S, in the hatched area of the line buffer 34 represents the image information of the area overlapped by the recording scan, and the image information So of the other part represents the image information of the area that is not overlapped. ing. Then, the image information S of such line buffer 34, ,
St are given to multipliers 35 and 36, respectively, where the multipliers are combined and edited by predetermined coefficients K, , and image information S,
, image information S as S2, and line buffer 3 as well.
7 is given and memorized. In this case, the coefficients of the multipliers 35 and 36 are image information a necessary for maintaining the continuity of the recorded image in the overlap area obtained by the recording scan of the thermal head 21, which is then stored in the line buffer 37. The thermal head 21 is also driven by the image information, but in this case, the image information NSt, which is the sum of the image information S and multiplied by a coefficient, is given to the group of heating elements on the upper part of the thermal head 21, and the image information S ! The coefficient is multiplied by the combined image information of the heating element at the bottom of the SJ thermal head 21.

be given to the group.

Thereby, for example, the applied pulse width of the thermal head 21 is controlled, and a gradation image is recorded while changing the transfer amount of the ink film 22.

FIG. 4 and FIG. 5 are for explaining in more detail the editing processing method for the overlapped area. That is, Fig. 4 fa) corresponds to the above-mentioned image information SI (the horizontal axis is the direction of the heat generating element array of the thermal head), and this information S is applied to the coefficients shown in Fig. 4 fb). The image information S as shown in FIG.
, get . On the other hand, FIG. 5 fa) corresponds to the above-mentioned image information S, and this information S has the coefficient 澹 shown in FIG. Image information S as shown in FIG. 5(C) is obtained by multiplying by a coefficient that reduces the weighting amount. And Figure 4 (C)
The image information SI shown in FIG. 5 is assumed to be the image information recorded on the upper part of the thermal head, and the image information 82' shown in FIG. 5(C) is assumed to be the image information recorded on the lower part of the thermal head. As a result, in the overlap area formed by the recording scan of the thermal head, the recorded image based on the image information S and the recorded image based on the image information S2 during the previous recording scan are superimposed, and as a result, conventionally The continuity of the recorded image used to be discontinuously lost at the boundary between recording scans, but now the recorded image changes smoothly in the overlap area, and the continuity of the recorded image is maintained, creating a good image without distortion. You will get better image quality.

Note that the coefficients shown in FIGS. 4 and 5 are: , K! Although shown as changing linearly, in principle, any value may be used, and the effect is particularly excellent when changing exponentially.

Next, another embodiment of the invention will be described.

FIG. 6 shows an image information editing circuit used in this embodiment. In this case, in the line buffer 38, the print image information of the print scan area is recorded as described above. Of these, the image information S, , S, in the overlapping area shown in the shaded area is selected for each line by the data selector 40.41 based on the line signal output from the line counter 39. The image information is stored in the line buffer 42, and then a thermal hect is driven based on the image information stored in the line buffer 42 to obtain a recorded image. In this case, the editing process in the overlap area will be explained in detail using FIG. 7. In the figure, W! indicates the width of the overlap area, and the figure shows a state in which the first printing scan has ended and the next printing scan is halfway underway. In this state, the image information in the overlap area is selected line by line using the data selectors 40 and 41 as described in FIG. Specifically, it decreases as it approaches the end of the thermal head.

As a result, in the overlap area formed by the recording scan of the thermal head, the unnaturalness of the recorded image is eliminated as described above, the continuity of the image is maintained, and good image quality without distortion can be obtained.

Of course, the image information may be selected by controlling the data selectors 40, 41 by the line counter 39 so as to be alternately selected every line.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications without changing the gist.

For example, in the case shown in Fig. 6, the recorded image information is selected line by line, but instead of the line counter, a bit counter is used to select the recorded image information bit by bit (this image information may be selected or line by line). Instead of a counter, a block counter that counts an arbitrary small area may be used to select image information for each arbitrary block.Of course, the selection of this image information may also be controlled by random numbers.

In addition, although the serial type has been described above, the present invention can also be applied to a line type in which a plurality of short heads are arranged in a staggered manner, for example. In this case, each short head is arranged so that a part of the recording scanning overlaps with the other, and the above-mentioned image information editing circuit that edits the image information given to these short heads, and the image information edited by this circuit. Transfer image information to each short head,
Distributing means are respectively provided so that each short head can obtain a recorded image including an overlapping area based on the image information edited by the image information editing circuit. Even in this case, the continuity of the image in the overlap region between the short heads can be maintained, and good image quality can be obtained.

Furthermore, although the above description has been made of recorded image information in which one recorded pixel is 8 bits, it is also possible to record image information in which the recorded pixel is y), that is, binary information indicating whether or not to record a pixel. good.

Furthermore, in the case of recording, such as character recording, in which discontinuity in images due to recording scanning is not very noticeable, or recording of slightly inferior image quality is sufficient, the above-mentioned overlap control may not be so necessary. Therefore, in anticipation of such a case, a changeover switch means may be provided to select whether or not to perform overlap control.

Finally, although the above description has consistently been made regarding a thermal transfer printer, it goes without saying that the present invention can be applied to other devices as well.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the main parts of an embodiment of the present invention. FIGS. 2(a) and 2(b) are diagrams for explaining the embodiment.
, FIG. 3 is a schematic configuration diagram showing the image information editing circuit used in the same embodiment, FIGS. 4 and 5 are diagrams for explaining the same embodiment, and FIG. 8 is a diagram for explaining the same embodiment. FIG. 9 is a schematic configuration diagram showing an example of a conventional image recording device; FIG. 9 is a diagram showing the resistance value distribution of a heating element of a thermal head used in the device;
The figure shows an example of a one-dimensional arrangement of conventional thermal heads.

Claims (5)

[Claims] (1) A recording head that performs recording scanning so that a part of the recording area overlaps, and a recording head that records and scans the image information in the overlapped area to maintain continuity of the recorded image in the overlapped area obtained by the recording scan. An image recording apparatus comprising an image information editing means for editing necessary image information and providing it to the recording head. (2) The image recording apparatus according to claim 1, wherein the recording head is of a serial type that records a continuous two-dimensional area by performing multiple recording scans. (3) The recording head described in claim 1 is characterized in that the recording head is of a line type having a plurality of short heads arranged so that a part of the recording scanning area overlaps. Image recording device. (4) The image recording apparatus according to claim 1, wherein the image information editing means includes means for weighting the image information of the overlap area by multiplying it by a predetermined coefficient. (5) The image information editing means includes means for selecting the image information of the overlap area for each predetermined line, for each predetermined bit, or for each predetermined small area using a data selector. The image recording device described in Section 1.