JP2006075996A - Sublimation type thermal transfer printer - Google Patents

Abstract

In a sublimation type thermal transfer printer, a print image quality can be maintained at a high quality, and a plurality of print sizes can be supported.
A thermal head 24 for heating an ink sheet 21 to form an image on the image receiving sheet 1 and a transport means TM for transporting the image receiving sheet via an image forming position of the thermal head 24 are provided. In the sublimation thermal transfer printer, the transport unit TM transports a plurality of types of image receiving sheets 1 having different sizes in the transport width direction at different image forming positions of the thermal head 24 in different transport rows that do not overlap the transport path. The thermal head 24 is configured to be capable of forming an image over a conveying row of a plurality of types of image receiving sheets 1, and the image forming positions for the plurality of types of image receiving sheets 1 in the thermal head 24 are the plurality of image forming positions. Each type of image receiving sheet 1 is fixedly configured.
[Selection] Figure 1

Description

  The present invention relates to a sublimation type thermal transfer printer provided with a thermal head that heats an ink sheet to form an image on the image receiving sheet, and a conveying unit that conveys the image receiving sheet via an image forming position of the thermal head. About.

Such a sublimation thermal transfer printer is a printer of a type in which ink contained in an ink sheet is heated by a thermal head and thermally transferred onto an image receiving sheet as described in Patent Document 1 below. By changing the heating amount, a continuous gradation can be expressed with a single pixel.
Conventionally, a sublimation thermal transfer printer is generally often configured as a printer dedicated to a specific print size.
JP-A-11-157153

Therefore, conventionally, it is inconvenient when it is desired to print with various print sizes.
The present invention has been made in view of such circumstances, and an object of the present invention is to be able to cope with a plurality of print sizes while maintaining high print image quality.

  The present invention relates to a sublimation type thermal transfer printer provided with a thermal head that heats an ink sheet to form an image on the image receiving sheet, and a conveying unit that conveys the image receiving sheet via an image forming position of the thermal head. The conveying means is configured to convey a plurality of types of image receiving sheets having different sizes in the conveying lateral width direction at different image forming positions of the thermal head in different conveying rows that do not overlap the conveying path. The head is configured to be capable of forming an image over a conveying row of a plurality of types of image receiving sheets, and an image forming position for the plurality of types of image receiving sheets in the thermal head is fixedly set for each of the plurality of types of image receiving sheets. Configured.

In other words, in order to be able to cope with print processing with a plurality of print sizes with a single thermal head, the image receiving target that is the target of the print image out of the print sizes that are assumed to be used is simply considered. It is considered that it is sufficient to provide a thermal head having a size that can cover the largest sheet in the lateral width direction of the sheet.
However, in the production of photographic prints, there is a print mode called a borderless print in which an image is formed on the entire surface of the image receiving sheet without an edge of a white background around the image, and there are a plurality of print sizes. When producing a borderless print, there is a problem that the image quality of the print image is deteriorated simply by considering only the dimensions of the thermal head as described above.

More specifically, in the aspect of deterioration of the image quality of the print image, a light streak pattern extending in the conveyance direction of the image receiving sheet is generated in the print image.
This streak pattern is obtained by setting the image formation width by the thermal head (that is, the heating width of the thermal head) slightly longer than the length in the conveyance width direction of the image receiving sheet when producing a borderless print. appear. The reason for providing the difference in length is to prevent the background color of the image receiving sheet from appearing on the image surface even if the conveying position of the image receiving sheet is slightly changed.
When an ink sheet is heated by a thermal head to form an image, the portion of the image formation width by the thermal head that is in contact with the image receiving sheet via the ink sheet is received even if heated for ink transfer. While heat is radiated through the sheet, the edge portion that is not in contact with the image receiving sheet has no heat radiating effect by the image receiving sheet, resulting in extremely high temperature.

Due to this temperature rise, the heat generating element of the thermal head is altered and the characteristics change.
When printing on a wider image-receiving sheet with a thermal head under such circumstances, an image is formed on the image-receiving sheet with a heating element whose characteristics have changed due to a rise in temperature. Transfer cannot be performed, and the streak pattern as described above is generated.
To avoid the occurrence of such streak patterns, it is possible to replace the print head with a dedicated thermal head each time the print size is changed, but a mechanism for replacing the thermal head is required. Thus, the apparatus configuration becomes extremely complicated.

Therefore, when using multiple types of image receiving sheets with different sizes in the transport width direction, the transport row of the multiple types of image receiving sheets transports the image formation position of the thermal head in a state where the respective transport paths do not overlap each other. And the size of the thermal head is configured such that one thermal head has a width capable of forming an image over a conveying row of a plurality of types of image receiving sheets. Assume that the image forming position with respect to the image receiving sheet is fixedly set for each of a plurality of types of image receiving sheets.
As a result, even in the thermal head, even if a portion where the characteristics are changed near the edge of the passing position of the image receiving sheet of each size, the changed portion is not used for image formation near the center of the image. .

According to the present invention, it is ensured that even if a portion having a characteristic change occurs near the edge of the passing position of each size of the image receiving sheet, the changed portion is not used for image formation near the center of the image. Therefore, it is possible to prevent a streak pattern from occurring in the printed image.
As a result, the print image quality can be maintained at a high quality, and a plurality of print sizes can be supported.

Embodiments of a sublimation type thermal transfer printer of the present invention will be described below with reference to the drawings.
[Schematic configuration of sublimation thermal transfer printer PR]
In the sublimation type thermal transfer printer PR of the present embodiment, as schematically shown in FIG. 1, three prints for forming yellow, magenta, and cyan images on an image receiving sheet 1 that is an image forming target member, respectively. An overcoat head 14 that forms a protective layer on the image forming surface of the image receiving sheet 1 and is located downstream of the heads 11, 12, and 13 and the cyan print head 13. A cutter 15 is provided for cutting the formed image receiving sheet 1 into a predetermined print size.
The image receiving sheet 1 is supplied in a long length from the image receiving sheet roll 2 in a state where the image receiving sheet 1 is wound up in a roll shape, and is processed by the print heads 11, 12, 13 and the overcoat head 14. Then, it is cut by the cutter 15 and discharged onto the tray 16.

[Schematic configuration of print heads 11, 12, 13, etc.]
Each of the print heads 11, 12, 13 and the overcoat head 14 basically has the same structure, and as shown in FIG. 2, the ink sheet 21 (overcoat sheet 41 in the overcoat head 14. (Same as above), a take-up roll 23 for winding the ink sheet 21 after image formation, a thermal head 24 for heating the ink sheet 21, and the image receiving sheet 1 and the ink sheet 21 are bonded to the thermal head 24. A driving roller 25 for driving and conveying, a guide roller 26 for guiding the ink sheet 21, and a conveying roller 27 for driving and driving the image receiving sheet 1. Further, image forming positions of the print heads 11, 12, and 13 are provided. (Contact position of thermal head 24) and image receiving position via protective layer formation position of overcoat head 14 A conveyance guide 28 is provided with over sheet 1 in order to convey guide. Conveying means TM that includes the driving roller 25 and the conveying roller 27 and conveys the image receiving sheet 1 via the image forming position of the thermal head 24 is configured.

The sublimation type thermal transfer printer PR of the present invention is configured to be capable of forming images on a plurality of types of image receiving sheets 1 having different sizes in the conveyance width direction. In the present embodiment, there are three sizes in the conveyance width direction. A case corresponding to the image receiving sheet 1 will be described as an example.
As shown in the perspective view of FIG. 6, three image receiving sheet rolls 2 having different sizes in the conveyance width direction are loaded side by side in the conveyance width direction of the image receiving sheet 1.
In the present embodiment, a case where any one of three types of image receiving sheets 1 having a horizontal width is selectively pulled out and conveyed and driven is illustrated. In FIG. 6, the central row having the largest size in the conveyance lateral width direction is illustrated. The image receiving sheet 1 is drawn out and conveyed. In the image receiving sheet rolls 2 at both ends, the state where the image receiving sheet 1 is drawn out and conveyed is indicated by a virtual line (two-dot chain line).
Note that the image receiving sheets 1 may be transported and driven simultaneously in a plurality of rows so that images can be formed simultaneously in a plurality of transport rows. In this case, in order to stop the conveyance drive of the image receiving sheet 1 for which image formation has been completed first, the conveyance driving force by the driving roller 25 and the conveyance roller 27 is applied for each type of image receiving sheet 1 (for each conveyance row of the image receiving sheet 1 It is preferable to enable ON / OFF independently.

Corresponding to the drive roller 25 and the conveyance roller 27 having conveyance widths that can convey the image receiving sheet 1 pulled out from the three image receiving sheet rolls 2 arranged in parallel in different conveyance rows that do not have overlapping conveyance paths. The thermal heads 24 of the print heads 11, 12, 13 and the overcoat head 14 are driven so that one thermal head 24 can form an image over the conveying rows of the three types of image receiving sheets 1. It has substantially the same length (length in the conveyance width direction) as the roller 25 and the like, and a large number of heating resistors are arranged in the main scanning direction at a high density over the entire length.
As shown in FIG. 5, which is a schematic diagram showing the relative positional relationship between the image receiving sheet 1 being conveyed and the thermal head 24 as viewed in the conveying direction, the image is received with the maximum size in the conveying lateral width direction (L2>L3> L1). A gap indicated by a width “G” is formed between the central conveyance row for conveying the sheet 1 and the left and right conveyance rows.
Each of the three types of image receiving sheet rolls 2 has a fixed loading position corresponding to the size, and the position and size of the gap with the width “G” are not changed. The image forming position with respect to the image receiving sheet is fixedly set for each of the three types of image receiving sheets.
In this way, by fixing the position of the conveying row of the image receiving sheets 1 of three types of sizes, even if the heating resistor located on the outer edge side of each conveying row is altered by heat and the characteristics change, Since the image receiving sheet 1 of another size does not pass through the position where the heat generating resistor has changed, deterioration of the formed image (generation of streak-like patterns) due to the change in the heat generating resistor can be prevented.

  A transport roller 42 for feeding the image receiving sheet 1 on which an image and a protective layer are formed to the cutter 15 is provided further downstream of the overcoat head 14 (see FIG. 1). This conveyance roller 42 also has a conveyance width in which the image receiving sheets 1 drawn from the three image receiving sheet rolls 2 arranged in parallel can be conveyed in different conveyance rows.

[Control configuration of sublimation thermal transfer printer PR]
As shown in the block diagram of FIG. 3, a conveyance motor 31 is provided to convey and drive the image receiving sheet 1, and by this conveyance motor 31, the drive roller 25 of each print head 11, 12, 13 or overcoat head 14 and The transport roller 27 and the transport roller 42 are integrally rotated. Although not shown in the drawing, each unit is also provided with a motor for winding and driving the ink sheet 21 of each print head 11, 12, 13 and the overcoat sheet 41 of the overcoat head 14 with a predetermined tension. Yes.
In FIG. 1, the thermal head 24 provided in each of the print heads 11, 12, 13 is “Y” for the yellow print head 11 and “m” for the magenta print head 12. “M” and “C” are added to the cyan print head 13 in parentheses for distinction.
The sublimation type thermal transfer printer PR is provided with a print control device PC for controlling each part such as the thermal head 24 and the conveyance motor 31, and the print control device PC has an image input which is a supply source of print data. The device IS is connected. The image input device IS is composed of, for example, a personal computer.

[Schematic configuration of print control device PC]
As shown in FIG. 4, the print control apparatus PC has a YMC system of 8-bit gradation for printing the image data input from the image input apparatus IS by the print heads 11, 12, 13. An image processing device 51 having a basic function of conversion into color representation image data, a thermal head data buffer 52 for storing and holding YMC-based representation image data generated by the image processing device 51, and a thermal head A heating pulse output circuit 53 for controlling each heating resistor of the thermal head 24 in accordance with 8-bit gradation image data stored in the data buffer 52, a motor drive circuit 54 for driving the carry motor 31, and an image receiving device. A conveyance control device 55 that performs conveyance control of the sheet 1 is provided.
The thermal head data buffer 52 and the two heating pulse output circuits 53 are provided for each of the three print heads 11, 12, and 13. In FIG. 4, only one is shown. Yes.

The heating pulse output circuit 53 reads the 8-bit gradation image data stored in the thermal head data buffer 52, and continuously applies the heating pulse having the number of pulses set according to the gradation value. Output to the head 24. The heating element of the thermal head 24 is switched between energization and non-energization depending on the presence or absence of the heating pulse, and is energized while the heating pulse is being input to heat the ink sheet 21.
The amount of ink transferred from the ink sheet 21 to the image receiving sheet 1, that is, the print density of that pixel, depends on how many heating pulses are incident while the conveying motor 31 conveys the image receiving sheet 1 by one pixel width. Change.
The data transmission timing from the thermal head data buffer 52 to the heating pulse output circuit 53 is controlled by the conveyance control device 55 that manages the conveyance position of the image receiving sheet 1, and every time the image receiving sheet 1 is conveyed by one pixel width. In addition, a signal indicating the data transmission timing is output from the transport control device 55 to the thermal head data buffer 52.

[Overview of print operation]
Next, the printing operation of the sublimation type thermal transfer printer PR having the above configuration will be schematically described.
When the image processing device 51 receives image data for one order from the image input device IS, the processing result is written in the thermal head data buffer 52.
Since each data storage area of the thermal head data buffer 52 corresponds to the heating resistor of each thermal head 24, when writing the converted data from the image processing device 51 to the thermal head data buffer 52, A write address is designated in consideration of the position of the conveyance row of the image receiving sheet 1 that is in charge of the print size of the image.
Further, when a plurality of print sizes are designated within one order, before the image data is written from the image processing device 51 to the thermal head data buffer 52, images of the same print size are continuously displayed. The order of the images is rearranged in advance.

The conveyance control device 55 instructs the leading edge drawing mechanism (not shown) to pull out the leading edge of the image receiving sheet 1 that is in charge of the designated print size from the image receiving sheet roll 2. When the leading edge is in a state of being conveyed and driven by the conveying roller 27, the conveying position of the image receiving sheet 1 is specified by the conveying timing signal input from the motor drive circuit 54.
When the leading edge of the image receiving sheet 1 is conveyed to a predetermined print start position, first, output of a signal indicating the data transmission timing to the thermal head data buffer 52 of the yellow print head 11 is started.

Thereafter, for the magenta print head 12 and the cyan print head 13, similarly, a signal instructing the output of the storage data of the thermal head data buffer 52 is sent from the conveyance control device 55, and the color is printed on the image receiving sheet 1. Images are formed.
The image receiving sheet 1 on which the protective layer is formed by the overcoat head 14 is cut into a predetermined print size by the cutter 15 and finished as a photographic print.
When the print size is switched within one order, the image receiving sheet 1 that has been used so far is wound around the image receiving sheet roll 2 and the same processing as described above is repeated for the image receiving sheet 1 that is in charge of the changed print size.

[Another embodiment]
Hereinafter, other embodiments of the present invention will be listed.
(1) In the above embodiment, the driving roller 25 and the conveying roller 27 are exemplified as the conveying unit TM that conveys the image receiving sheet 1. However, the conveying unit TM conveys the image receiving sheet 1 with a conveying belt, for example. The specific configuration of can be variously changed.
(2) In the above embodiment, the case where the image receiving sheet 1 having three sizes in the conveyance width direction is handled is exemplified. However, the present invention is also applicable to the case where the image receiving sheets 1 having two types or four or more sizes are handled. Can be applied.
(3) In the above embodiment, the transport unit TM illustrates the case of transporting the long image receiving sheet 1 pulled out from the image receiving sheet roll 2, but it is pulled out from the image receiving sheet roll 2 to obtain a predetermined length. The image receiving sheet 1 after being cut to the print size may be conveyed and an image may be formed on the image receiving sheet 1 after the cutting by the thermal head 24.
Further, instead of the image receiving sheet roll 2, the image receiving sheet 1 that has been cut in advance to the print size may be supplied.

1 is a schematic configuration diagram of a sublimation thermal transfer printer according to an embodiment of the present invention. The enlarged view of the print head concerning an embodiment of the invention Schematic control block diagram according to an embodiment of the present invention Main part control block diagram concerning embodiment of this invention The figure which shows the positional relationship of the thermal head concerning embodiment of this invention, and an image receiving sheet. 1 is a schematic perspective view of a sublimation type thermal transfer printer according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image receiving sheet 21 Ink sheet 24 Thermal head TM Conveyance means

Claims (1)

A sublimation type thermal transfer printer provided with a thermal head for heating an ink sheet to form an image on the image receiving sheet, and a conveying means for conveying the image receiving sheet via an image forming position of the thermal head,
The transport means is configured to transport a plurality of types of image receiving sheets having different sizes in the transport width direction at different image forming positions of the thermal head in different transport rows that do not overlap the transport path,
With one thermal head, it is configured to be able to form an image across multiple types of image receiving sheet conveyance rows,
A sublimation type thermal transfer printer in which image forming positions for the plurality of types of image receiving sheets in the thermal head are fixedly set for the plurality of types of image receiving sheets.

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