JP2009039937A - Printer and printing control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer capable of improving the image quality performance of a printed image and saving energy.
A printer according to the present invention controls the sublimation amount of ink applied to an ink sheet according to the number of energizations of a heating element of a thermal head, and changes the density of an image by changing the amount of ink adhering to printing paper. Express. Then, based on the gradation representing the density of the pixel to be printed at present, the front-filling / bottom-packing determination circuit 51, the front-packing / bottom-packing data conversion circuit 52, and the current-carrying data conversion circuit as energization control means for controlling the energization timing to the heating element 53, and an energization number counter 54 is provided.
[Selection] Figure 6

Description

  The present invention relates to a printer and a print control method, and more particularly to a printer and a print control method for performing printing by sublimating ink applied to an ink sheet using a thermal head in which a plurality of heating elements are arranged.

  2. Description of the Related Art A sublimation type printer is widely known in which a dye applied to an ink ribbon is sublimated and adhered to a dedicated sheet by heat generated when a thermal head having a plurality of heating elements arranged in a row is energized. In this sublimation printer, a multi-pulse method is generally used as a method for controlling the amount of dye sublimated from an ink ribbon.

In order to solve the problem of heat accumulation peculiar to the thermal head, Japanese Patent Application Laid-Open No. H10-228707 proposes a technique for controlling the position (pixel energization timing) for forming pixels.
JP 2000-318200 A

  The above-described prior art is to select a position (timing for energizing a heating element) for forming a pixel in accordance with image data to be printed (natural image or text data).

  Therefore, there is a problem that application is difficult in the case of an image in which a natural image and text data are mixed.

  An object of the present invention is to provide a printer and a print control method capable of improving the image quality performance of a printed image and saving energy.

  In order to achieve the above object, a printer according to claim 1 is a printer that performs printing by sublimating ink applied to an ink sheet using a thermal head in which a plurality of heating elements are arranged. Control means for changing the gradation of the pixels formed on the printing paper by controlling the number of energizations to the heating element of the thermal head based on the control means, the control means based on the gradation of the pixels to be formed, It is characterized by controlling energization timing.

  According to a sixth aspect of the present invention, there is provided a printing control method for a sublimation printer that performs printing on a sheet using a thermal head in which a plurality of heating elements are arranged, and to the heating element of the thermal head based on print data. The gradation of the pixels formed on the printing paper is changed by controlling the number of energizations, and the energization timing of the pixels is controlled based on the gradation of the pixels to be formed.

  According to the printer of the present invention, it is possible to improve the image quality performance of a printed image and save energy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of a camera direct print system including a printer according to an embodiment of the present invention.

  In FIG. 1, the present camera direct print system is configured by connecting a digital camera 1 and a direct printer (sublimation printer) 2 for outputting a digital image to a printing paper via a USB cable 3.

  Here, the sublimation printer controls the sublimation amount of the ink applied to the ink sheet according to the number of energizations to the heating element of the thermal head, and changes the density of the image (gradation) by changing the amount of ink adhering to the printing paper ) Is a printer that expresses the above.

  When the image transfer is executed, the digital camera 1 and the direct printer 2 negotiate according to the USB protocol, and the image transfer starts. The data is communicated through the USB cable 3.

  The direct printer 2 includes a composite card slot 4 for exchanging image data with a plurality of types of memory cards.

  The direct printer 2 includes an LCD monitor 5 for displaying a graphical user interface (GUI) for operating the direct printer, a power switch 6, and various switches 7 as operation members.

  FIG. 2 is a block diagram of the direct printer in FIG.

  In the direct printer 2, the CPU 10 controls the entire apparatus, processes a digital image, and controls USB communication.

  The CPU 10 functions as a control unit that changes the gradation of the pixels formed on the printing paper by controlling the number of energizations to the heating element of the thermal head 14 based on the printing data. Further, the control means determines whether to energize mainly using the first half or mainly energize using the second half of the energization period in which energization can be performed on the pixels to be formed according to the gradation of the pixels to be formed. .

  The flash memory 11 stores a program for controlling the apparatus, icon data for GUI displayed on the LCD monitor 5, frame data for image synthesis, and the like.

  The SDRAM 12 is a work memory that is used during program operation and image processing, and temporarily stores data to be displayed on the LCD monitor 5. The head motor control IC 13 controls the thermal head, the LF motor, and the UD motor. A functional block for controlling the position (timing) for pixel formation according to the gradation (density) of the image data is also included in the head motor control IC 13.

  In the thermal head 14, 1280 heating elements are arranged in a row. In the present invention, a drive control system for on / off control of the heating element is employed. The motor driver 15 drives an LF motor and a UD motor. Here, the LF motor is a stepping motor for conveying printing paper, and the UD motor is a motor for moving the thermal head 14 up and down.

  The LCD driver 16 drives the LCD monitor 5. A USB HUB 17 for distributing USB protocol data is connected to the card memory controller 18 and the USB A connector. The card memory controller 18 has a USB interface and is connected to the composite card slot 4.

  FIG. 3 is a schematic diagram for explaining the configuration of the image output unit of the direct printer in FIG. 1 and the basic principle of the sublimation printing (printing) method.

  The sublimation printing method is a method using a diffusion phenomenon of a dye (pigment). The ink sheet 31 is obtained by applying three color (yellow, magenta, and cyan) dyes to a plastic sheet. The ink sheet 31 is overlapped with the dedicated printing paper 32 and is sandwiched between the thermal head 14 and the platen roller 34, and is sublimated / thermally diffused on the dedicated printing paper 32 by the heat of the thermal head 14. Get.

  In addition, in order to ensure the coloring of the sublimation dye 35 of the ink sheet 31, a receiving layer 36 mainly composed of a polyester resin is applied to the dedicated printing paper 32. At this time, gradation can be given by controlling the heat applied to the thermal head 14.

  By giving gradation to each of the three colors (yellow, magenta, and cyan) and printing (printing) the same part of the photographic paper (dedicated printing paper 32), high-definition full-color printing in units of one pixel can be realized.

  With reference to FIG. 8, the operation of the printer according to the present embodiment will be described. These processes are executed by the CPU 10 reading a program from a program memory (not shown) and performing control and arithmetic processing of each unit based on the program.

  The printer 2 acquires an image to be printed from the digital camera 1 connected by USB or the memory card mounted in the card slot 4 (step S80). Next, the image data to be printed acquired in step S80 is converted into image data for printing to generate print data (step S81).

  The image data for printing is generated for each color data of yellow (Y), magenta (M), and cyan (C). In step S82, the printing paper is fed from a printing paper cassette (not shown), and the printing paper is conveyed to the print start position. In steps S83 and S84, the conveyance of the printing paper for printing is started by controlling the LF motor, and printing is performed by the thermal head based on the printing image data generated in step S81.

  When printing for one color is completed, it is confirmed whether printing of all colors of YMC is completed (step S85). If not completed, the printing paper at the printing end position is reversely conveyed and returned to the printing start position (step S86), and the printing process of steps S83 and S84 is performed for the next color. When the printing of all three colors is completed, an overcoat process is performed on the printing screen (step S87), and the printing process ends.

  With reference to FIG. 9, the state of pixel formation on the printing paper in the sublimation printer will be described. When the maximum gradation is 256, it is necessary to turn on the heating element 256 times in order to express the maximum gradation.

  Here, the drive of the heating element is controlled in units of a predetermined time, but a unit time for turning on once is defined as a cell. When the sublimation head is driven for one cell, the dye having a density of one gradation adheres to the recording paper.

  During driving of the second cell, the recording medium is conveyed by the LF motor in the conveyance direction indicated by the arrow in the figure, so the second gradation is shifted to the opposite side of the recording paper conveyance direction from the first gradation. . Accordingly, when the 256th gradation of the maximum gradation is recorded, the pixel shape becomes an ellipse extending rightward as shown at the bottom of FIG.

  When the image data corresponding to the pixel to be printed has a large gradation and a dark color is printed, the heating element is turned on for a long time, and excess heat is accumulated in the thermal head, affecting the next pixel to be printed. The problem of giving up arises.

  Therefore, in the sublimation type printer of this embodiment, each pixel is formed by the following method. This print control method will be described with reference to FIG.

  First, print data corresponding to the pixels to be formed on the printing paper is read for one pixel (step S100), and the gradation of the read print data is determined (step S101). In the present embodiment, it is determined that the gradation is higher when the gradation is higher than the intermediate gradation of the maximum gradation, and light when the gradation is lower than the intermediate gradation of the maximum gradation.

  If the gradation is higher than the intermediate gradation of the maximum gradation, the pixels are formed by the front-filling method (step S102). If the gradation is lower than the intermediate gradation of the maximum gradation, the pixel is formed by the back-packing method. Is formed (step S103). The front-filled printing system and the back-filled printing system will be described next.

  A plurality of heating elements are arranged on the thermal head, and a plurality of pixels can be formed by printing one line. That is, when one line is printed, the above processing is performed on a plurality of pixels to be printed, and it is determined whether each pixel is to be front-justified or back-justified. These processes are executed under the control of the head / motor control IC.

  FIG. 4 is a diagram for explaining pre-packing and post-packing in the thermal head multi-drive system.

  Here, for easy understanding, the number of times that the maximum density can be printed on the dedicated printing paper 32, that is, the maximum number of gradations is 32 gradations. When the heating element of the thermal head 14 is energized once, one gradation is obtained. FIG. 4 illustrates a heating element energization pattern of one pixel, and one gray ellipse represents one gradation. Actually, the ellipses overlap, but here they are shown separately one by one for ease of understanding.

  Since the maximum density is 32 gradations, each pixel can be energized 32 times. FIG. 4 illustrates the case of forming pixels with 16 gradations. At this time, it is only necessary to energize the heating element 16 times. Among the 32 energization timings of the 16 gradations, energization at the front 1 to 16 is referred to as front packing, and energization at the rear 17 to 32 is referred to as back packing.

  FIG. 5 is a diagram for explaining the influence of livestock heat of the thermal head in FIG.

  In this figure, the horizontal axis represents the number of pixels (time), and the vertical axis represents density. It is a graph when 10 types of pixels are continuously printed by changing five types of driving methods of the thermal head 14. At this time, printing is performed with the same energy amount for 10 pixels. The density is determined by the sublimation amount of the ink, and the amount of sublimation depends on the heat level of the thermal head 14, so that the higher the density, the higher the temperature.

  In this graph, it can be seen that the density gradually increases as it goes to the right in any recording method. This is because the heat of the previous recording remains, and represents the thermal effect of the thermal head.

  On the other hand, since the thermal response of the thermal head 14 is not so fast, heat is not generated at the moment when the heating element is energized. For this reason, a certain number of energizations are required before the ink sublimation phenomenon occurs. become. Conventionally, in order to obtain the expected density when expected, a preheating method in which the thermal head 14 is energized in advance has been employed. This method is used when the concentration change is abrupt.

  Therefore, when it is desired to increase the pixel density, it is advantageous to be affected by the heat of the pixel in front of the thermal head 14, and when it is desired to reduce the density, the pixel in front of the thermal head 14 is advantageous. It is a good idea not to be affected by heat. The present invention achieves this.

  FIG. 6 is a configuration diagram of a front and back-packing determination data creation block provided in the head / motor control IC in FIG.

  In FIG. 6, the print data is read out from the buffer memory 50 pixel by pixel, and the front-fill / post-fill determination circuit 51 determines whether to pre-fill or back-fill (processing in steps S100 and S101 in FIG. 10). For example, in the case of a gradation lower than the intermediate gradation of the maximum gradation (density), conversion is performed by the front-filling / filling-data conversion circuit 52 as the backfilling data.

  In the case of a gradation higher than the intermediate gradation of the maximum gradation (density), conversion is performed by the front-filled / post-packed data conversion circuit 52 as the front-filled data. Thereafter, the energization data conversion circuit 53 converts the data into data for energizing the heating element, and the converted data is temporarily stored in the converted data memory 55.

  The data stored in the post-conversion data memory 55 is read based on the value of the energization counter 54 and supplied to the thermal head 14 as serial data.

  As described above, in this embodiment, the gradation indicating the density of the pixel to be printed at present is determined by the front-filling / bottom-packing determination circuit 51, the front-packing / filling data conversion circuit 52, the energization data conversion circuit 53, and the energization frequency counter 54. Based on the above, the energization timing to the heating element is controlled. That is, the pre-packing and post-packing determination circuit 51, the pre-packing and post-packing data conversion circuit 52, the energization data conversion circuit 53, and the energization frequency counter 54 function as means for controlling energization.

  In addition, if the gradation of the pixel to be printed is lower than the intermediate gradation of the maximum gradation, post-printing is performed to match the end of the gradation, and the gradation of the pixel to be printed is equal to or higher than the intermediate gradation of the maximum gradation. Performs a pre-stamped print that matches the tones of the tone.

  As a result, it is possible to obtain a high-quality printing result with good contrast. Furthermore, by effectively utilizing the residual heat of the thermal head 14, less energy is given to the thermal head 14, and an energy saving effect can be expected.

  In the above-described embodiment, switching between front-packing and back-packing is determined using the intermediate gray level of the maximum gray level as a threshold value. However, the present invention is not limited to this, and an appropriate gradation is selected according to the characteristics of the thermal head. It may be a threshold value.

  In the above-described embodiment, the determination of front-end and back-end clogging is performed only with the gradation of the pixel to be printed. Next, the gradation of the pixel to be printed, the gradation of the previous pixel, and the subsequent pixels A case will be described in which pre- and post-packing determination is performed using the gradation of the above as a determination factor.

  FIG. 7 is a diagram for explaining a pre-filling and post-packing determination method in consideration of the previous and subsequent pixels.

  First, a description will be given of how to determine whether the image to be printed on the first line is pre-filled or post-filled.

  If the pixel to be printed on the first line is lower (lighter) than the gradation of a certain reference pixel, and the pixel on the second line is also lower (lighter), 1 is considered in consideration of the influence on the pixel on the second line. The pixels on the line are front-filled.

  When the pixel to be printed on the first line is lower (lighter) than the gradation of a certain criterion pixel, and the second line pixel is higher (darker), the density of the second line pixel is slightly higher. Thus, the pixels on the first line are back-filled.

  When the pixel to be printed on the first line is higher (darker) than the gradation of a certain reference pixel, and the pixel on the second line is low (light), the influence of the residual heat on the second line is reduced as much as possible. Therefore, the pixels on the first line are left-justified.

  If the pixel to be printed on the first line is higher (darker) than the gradation of a certain reference pixel, and the pixel on the second line is also higher (darker), the second line should be affected even slightly Therefore, the pixels on the first line are back-filled.

  Next, a description will be given of how to determine the front-end and back-end of the image to be printed on the second and subsequent lines up to one line before the final line.

  Here, it is assumed that the line to be printed is an N line, the previous line is the N−1 line, and the subsequent line is the N + 1 line.

  When the gradation is lower (lighter) than the pixels of a certain criterion in all of the N line, N-1, and N + 1 lines, the N-1 line is back-packed to minimize the influence of the residual heat of the N-1 line.

  In the case where the gradation is lower (lighter) than the determination reference pixel having the N line and the N + 1 line, and the gradation is high (dark) in the N + 1 line, the influence of the residual heat of the N-1 line is reduced as much as possible, and The effect of residual heat on the N + 1 line must be increased as much as possible. Therefore, the pixels on the N line are back-filled.

  If the N-line pixels are higher (darker) than the gradation of a certain criterion, and the N-1 line and N + 1 line have low gradation (light), they are affected by the residual heat of the N-1 line. Also, in order to reduce the influence of the remaining heat on the N + 1 line as much as possible, the pixels on the N line are front-filled.

  When the N-line and N + 1-line pixels are higher (darker) than the gradation of a certain criterion and the N-1-line pixels are lower (lighter), the influence of the residual heat from the N-1 line is slightly affected. However, as received, the pixels on the N line are pre-filled.

  If the N-line and N + 1-line pixels are lower (lighter) than the gradation of a certain criterion and the N-1-line pixels are higher (darker), the influence of the residual heat of the N-1-line pixels is affected. In order to reduce the number of pixels, the pixels on the N line are back-filled.

  If the N-line pixels are lower (lighter) than the gradation of a certain criterion and the N-1 and N + 1 line pixels are high (dark), the influence of the residual heat of the N-1 line is minimized. In order to give the slight influence of the residual heat on the N + 1 line, the pixels on the N line are back-filled.

  If the N-line and N-1-line pixels are higher (darker) than the gradation of a certain criterion and the N + 1-line pixels are low (light), they are affected by the residual heat of the N-1 line, In addition, in order to reduce the influence of the remaining heat on the N-1 line as much as possible, the pixels on the N line are front-filled.

  If the pixels of the N line, N-1 line, and N + 1 line are all higher (darker) than the gradation of a certain criterion, the pixels of the N line are set to be easily affected by the residual heat of the N-1 line. Is pre-packed.

  Finally, a description will be given of how to determine whether the pixels to be printed on the final line are pre-filled and post-filled.

  If the pixel of the final line is lower (lighter) than the gradation of a certain criterion and the pixel one line before the final line is also low (light), it is hardly affected by the residual heat one line before the final line. In order to do this, the pixels on the last line are back-filled.

  If the pixel of the final line is higher (darker) than the gradation of a certain criterion and the pixel one line before the final line is high (dark), it is easily affected by the residual heat of the previous line one line. In order to do this, the pixels in the final line are pre-filled.

  When the pixel of the last line is lower (lighter) than the gradation of a certain criterion and the pixel one line before the last line is high (dark), it is hardly affected by the residual heat one line before the last line. In order to do this, the pixels in the final line are back-filled.

  If the pixel of the last line is higher (darker) than the gradation of a certain criterion and the pixel one line before the final line is higher (darker), it is easy to be affected by the residual heat one line before the final line. In addition, the pixels on the final line are front-filled.

  According to the present embodiment, the energization control unit controls the energization timing to the heating element based on the gradation of the pixel one pixel before the pixel to be printed and the gradation of the pixel one pixel after.

  With this processing as well, it is possible to obtain a high-quality print result with good contrast and darkness as described above. Furthermore, by effectively utilizing the residual heat of the thermal head 14, less energy is given to the thermal head 14, and an energy saving effect can be expected.

1 is a configuration diagram of a camera direct print system including a printer according to an embodiment of the present invention. It is a block diagram of the direct printer in FIG. FIG. 2 is a schematic diagram for explaining a basic principle of a configuration of an image output unit of the direct printer and a sublimation printing (printing) method in FIG. 1. It is a figure explaining the front packing and the back packing in the multi-drive system of the thermal head in FIG. It is a figure explaining the influence of livestock heat of the thermal head in FIG. FIG. 3 is a configuration diagram of a pre-packing determination data creation block included in the head motor control IC in FIG. 2. It is a figure explaining the before-filling after-packing determination method which considered the pixel before and behind. FIG. 3 is a flowchart showing a procedure of print processing executed by the direct printer of FIG. 2. FIG. FIG. 3 is a diagram illustrating how pixels are formed on a printing paper in the direct printer of FIG. 2. It is a flowchart which shows the procedure of the pre-packing and back-packing selection processing performed by the direct printer of FIG.

Explanation of symbols

1 Digital Camera 2 Direct Printer 3 USB Cable 4 Compound Card Slot 5 LCD Monitor 6 Power Switch 7 Various Switches 10 CPU
11 Flash memory 12 SDRAM
13 Head motor control IC
14 Thermal head 15 Motor driver 16 LCD driver 18 USB HUB
19 Card Memory Controller 31 Ink Sheet 32 Dedicated Printing Paper 34 Platen Roller 35 Sublimation Dye 36 Receiving Layer 50 Buffer Memory 51 Front-Clogging / Clogging Judgment Circuit 52 Front-Cuffing / Clogging Data Conversion Circuit 53 Energization Data Conversion Circuit 54 Energization Time Counter 55 Conversion Data Memory

Claims (10)

A printer that performs printing by sublimating ink applied to an ink sheet using a thermal head in which a plurality of heating elements are arranged,
Control means for changing the gradation of the pixels formed on the printing paper by controlling the number of energizations to the heating element of the thermal head based on the printing data,
The printer according to claim 1, wherein the control unit controls energization timing based on a gradation of a pixel to be formed.   The printer according to claim 1, wherein the control unit controls energization timing based on a gradation of a pixel to be formed and a gradation of a pixel one line before the pixel.   The printer according to claim 1, wherein the control unit controls energization timing based on a gradation of a pixel to be formed and a gradation of a pixel after one line of the pixel.   The control means controls energization timing based on a gradation of a pixel to be formed, a gradation of a pixel one line before the pixel, and a gradation of a pixel one line after the pixel. Item 1. The printer according to Item 1.   The control means determines whether to energize mainly using the first half or mainly energize using the second half of the energization period in which energization is possible for the pixels to be formed, according to the gradation of the pixels to be formed. The printer according to claim 1. A printing control method for a sublimation printer that prints on paper using a thermal head in which a plurality of heating elements are arranged,
By controlling the number of energizations to the heating element of the thermal head based on the print data, the gradation of the pixels formed on the printing paper is changed, and the energization timing of the pixels is controlled based on the gradation of the pixels to be formed. A printing control method.   The printing control method according to claim 6, wherein the energization timing is controlled based on a gradation of a pixel to be formed and a gradation of a pixel one line before the pixel.   The print control method according to claim 6, wherein the energization timing is controlled based on a gradation of a pixel to be formed and a gradation of a pixel after one line of the pixel.   7. The printing according to claim 6, wherein energization timing is controlled based on a gradation of a pixel to be formed, a gradation of a pixel one line before the pixel, and a gradation of a pixel one line after the pixel. Control method.   According to the gradation of the pixel to be formed, it is determined whether to energize mainly using the first half or mainly to energize using the second half of the energization period in which the pixels to be formed can be energized. The printing control method according to claim 6.

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