JP2005262761A - Color thermal printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color thermal printing method capable of lowering illuminance of a magenta fixing lamp while a time for fixing is prevented from being prolonged. <P>SOLUTION: While a color thermal recording paper 11 is carried in the returning direction, an image is thermally recorded thereon by a thermal head 22. On the downstream side in the returning direction relative to a thermal head 22, a YM lamp 24 emitting a yellow fixing light and a magenta fixing light is arranged. On the upstream side in the returning direction, an M lamp 26 emitting a magenta fixing light is arranged. The recorded part on which the image is recorded by the thermal head 22 is delivered to the YM lamp 24 and is sequentially optically fixed. The recorded area where M-fixing is performed by the YM lamp 24 is carried in the carrying direction for recording of the next cyan image, and the M-fixing is performed by the M lamp 26 during this carrying. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color thermal printing method that uses color thermal recording paper, thermally records an image with a thermal head, and then performs light fixing on the recording area to obtain a color image.

  A color thermal recording paper (hereinafter simply referred to as recording paper) in which a thermal color developing layer for forming colors of yellow, magenta and cyan is sequentially formed on a support is used, and this recording paper is heated with a thermal head to produce three colors. A color thermal printer that obtains a full-color image by recording the images in the order of frames is known (see, for example, Patent Document 1 below). The thermal head includes a heat generating element array in which a large number of heat generating elements are arranged in the main scanning direction (width direction of the recording paper), and the recording paper is placed in the main scanning direction with the heat generating element array being pressed against the recording paper. The image is thermally recorded while being conveyed in the sub-scanning direction orthogonal to the.

  The heat-sensitive color developing layer of each color has a lower thermal sensitivity as the deep heat-sensitive color developing layer depends on the order in which the layers are arranged. Color is developed with thermal energy, and the intermediate magenta thermosensitive coloring layer develops with intermediate thermal energy. In addition, the yellow and magenta thermosensitive coloring layers are light-fixed to light in their specific wavelength ranges so that the upper thermosensitive coloring layer does not develop color when a deeper thermosensitive coloring layer is heated. The yellow and magenta thermosensitive coloring layers lose their coloring ability when irradiated with fixing light having a specific wavelength from the fixing light source.

  In the color thermal printer described in Patent Document 1 below, an optical fixing device is arranged on the downstream side in the recording direction in which the color thermal recording paper is conveyed during thermal recording with respect to the thermal head. The optical fixing device includes a yellow lamp and a magenta lamp, and these lamps are arranged side by side along the conveyance direction.

  It has also been proposed to use an LED instead of a fluorescent tube as a fixing light source (for example, Japanese Patent Application No. 2003-35431). Although each LED has a narrow emission wavelength range, the emission wavelength varies due to individual differences. For this reason, for example, when an LED is used as a yellow fixing light source, if the variation occurs, light fixing is performed on an unrecorded magenta thermosensitive coloring layer, and a part of the coloring ability is lost and the maximum There is a possibility that the color density may decrease. In order to prevent this, in the printer described in the above specification, a short wavelength cut filter is provided in the yellow fixing light source.

Japanese Patent No. 2711039

  However, when the yellow and magenta lamps are arranged as in the printer described in Patent Document 1, the yellow lamp position is farther from the thermal head than the magenta lamp. Becomes longer and the fixing time becomes longer.

  In addition, the magenta thermosensitive coloring layer has a lower fixing sensitivity than the yellow thermosensitive coloring layer, and therefore requires a larger amount of irradiation light than the yellow thermosensitive coloring layer. Therefore, the higher the illuminance of the magenta fixing lamp, the better. If the illuminance is high, the conveyance speed of the recording paper at the time of fixing can be increased, which contributes to shortening of the fixing time. On the other hand, lamps with high illuminance are expensive and have disadvantages such as large heat generation, so there is a demand to reduce the illuminance of the magenta fixing lamp.

  An object of the present invention is to provide a color thermal printing method capable of reducing the illuminance of a magenta fixing lamp while preventing the fixing time from being prolonged.

  In the color thermal printing method of the present invention, Y, M, and C thermal coloring layers that form colors of yellow, magenta, and cyan in order from the uppermost layer are provided on a support, and at least Y and M thermal printing layers are provided. The color-developing layer uses color thermal recording paper having photofixability with respect to Y and M fixing lights in respective specific wavelength ranges, and during the first conveyance of the color thermal recording paper in the first direction, The Y image is thermally recorded on the Y thermosensitive coloring layer by the thermal head, and the recording area is sent to the YM light source that is arranged on the downstream side in the first direction of the thermal head and emits both Y and M fixing lights. In a state where a filter for cutting M fixing light is inserted between the YM light source and the conveyance path, the YM light source irradiates the recording area with Y fixing light that has passed through the filter to fix the Y image. Record And the Y fixing step, and after the recording area is transported in the second direction opposite to the first direction and returned to the thermal head, during the second transport in the first direction, the M thermosensitive coloring layer The M area is thermally recorded, and the recording area is sent to the YM light source, and with the filter retracted from the insertion position, the recording area is irradiated with M fixing light by the YM light source. During M recording and M fixing step for photofixing the coloring layer, and during the second conveyance of the recording area in the second direction, the M fixing light is emitted on the upstream side in the first direction of the thermal head. An M fixing step for photofixing the M thermosensitive coloring layer with an M light source, and a C recording step for thermally recording a C image on the C thermosensitive coloring layer during the third transport in the first direction. Features.

  Further, during the C recording step, M fixing may be performed using an M light source.

  In the present invention, a YM lamp is arranged on the downstream side in the conveyance direction during recording and an M lamp is arranged on the upstream side with respect to the thermal head, and each color is transmitted by the YM lamp during conveyance during recording of each color image. After fixing the magenta image and fixing the magenta image, M fixing is performed by the M lamp while the recording paper is sent to a predetermined position for recording the cyan image, so that the fixing time is extended. Without making it happen, the illuminance of the M lamp can be lowered.

  In the color thermal printer 10 shown in FIG. 1, a recording paper roll 12 in the form of a roll of a long color thermal recording paper 11 is set. The paper feed roller 13 abuts on the recording paper roll 12 and rotates it to draw out the leading end of the color thermal recording paper 11 to the conveyance path. The drawn color thermal recording paper 11 is conveyed by the conveying roller pair 14. The printer 10 performs thermal recording of a full-color image and optical fixing of the color thermal recording paper 11 that has been thermal-recorded while reciprocally transporting the color thermal recording paper 11 in the feed direction and the return direction.

  The paper feed roller 13 and the transport roller pair 14 are driven by a drive motor 15. The controller 21 includes a CPU, a ROM, a RAM, and the like, and comprehensively controls each unit of the printer 10. The controller 21 controls the conveyance amount of the color thermal recording paper 11 by controlling the rotation amount of the drive motor 15.

  As is well known, the color thermosensitive recording paper 11 is formed by layering three thermosensitive coloring layers that color each color of Y (yellow), M (magenta), and C (cyan) in order from the upper layer on the support. It is. The color thermosensitive recording paper 11 has the highest thermal sensitivity of the yellow thermosensitive coloring layer as the uppermost layer and the lowest thermal sensitivity of the cyan thermosensitive coloring layer as the lowermost layer.

  Each of the yellow and magenta thermosensitive coloring layers is provided with a light fixing property by light in a specific wavelength range so that the uncolored portion of the upper thermosensitive coloring layer is not colored when the deep thermosensitive coloring layer is heated. Each thermosensitive coloring layer is photofixed by irradiating light of each wavelength after the image is thermally recorded. The yellow thermosensitive coloring layer loses its coloring ability when irradiated with yellow fixing light, which is blue-violet light having an emission peak wavelength of about 420 nm. When the magenta fixing light is irradiated, the coloring ability is lost.

  On the conveyance path of the color thermal recording paper 11, a thermal head 22 and a platen roller 23 that is disposed at a position facing the thermal head 22 and supports the color thermal recording paper 11 from the back side are arranged. As is well known, the thermal head 22 includes a heating element array 22a in which a large number of heating elements are arranged in a line along the main scanning direction (width direction of the color thermal recording paper). Each heating element generates thermal energy according to the density of the pixel. The heating element array 22a is brought into pressure contact with the color thermosensitive recording paper 11, and each thermosensitive coloring layer is heated to thermally record an image of each color of yellow, magenta, and cyan.

  The recording area of the color thermal recording paper 11 is once transported in the feed direction until it passes through the thermal head 22, and then thermal recording is performed while being transported in the return direction, but recording starts immediately after the transport in the return direction is started. Then, the conveyance of the color thermal recording paper 11 is not stabilized due to the tension fluctuation of the conveyance roller pair 14. Further, before starting thermal recording, a side edge of the color thermal recording paper 11 must be detected by an end detection sensor (not shown), and the driving range of the heating element array must be determined according to the position.

  For this reason, recording is started after performing a run in a predetermined section and a return direction before starting recording. In order to secure this run-up section, the recording area is conveyed in the feeding direction for a while after the recording start position exceeds the thermal head 22. Thereafter, the conveyance in the returning direction is started, and after passing the run, thermal recording is started when the recording start position reaches the thermal head 22.

  A YM lamp 24 that emits yellow fixing light and magenta fixing light is disposed on the downstream side in the returning direction (recording direction) with respect to the thermal head 22, and magenta fixing light is emitted on the upstream side thereof. An M lamp 26 is arranged. The YM lamp 24 and the M lamp 26 are, for example, LED arrays in which a plurality of LEDs are arranged in a matrix.

  As shown in FIG. 2, as the LED of the YM lamp 24, a blue LED having an emission wavelength peak in the vicinity of about 420 to 430 nm is used. This blue LED also emits magenta fixing light in the vicinity of 380 to 400 nm, although the yellow fixing light has a peak emission wavelength. Therefore, this wavelength region is used for fixing the magenta thermosensitive coloring layer.

  However, in yellow light fixing (Y fixing), if this magenta fixing light is irradiated, an unrecorded magenta thermosensitive coloring layer is fixed. Therefore, magenta fixing light is cut during Y fixing. A short wavelength cut filter 28 is provided. The short wavelength cut filter 28 cuts a wavelength region of about 410 nm or less. The short wavelength cut filter 28 is detachably provided between an insertion position where the short wavelength cut filter 28 is inserted between the YM lamp 24 and the conveyance path and a retreat position where the short wavelength cut filter 28 is retracted from the insertion position. The short wavelength cut filter 28 moves to the insertion position during Y-fixing, and moves to the retracted position during M-fixing. The short wavelength cut filter 28 is driven by a filter drive unit (not shown) including a drive motor and a moving mechanism. The initial position of the short-wavelength cut filter 28 is an insertion position, which moves to the retracted position during M-fixing, and returns to the insertion position again when M-fixing is completed.

  The light fixing by the YM lamp 24 is performed by sequentially irradiating fixing light to the recorded portion conveyed in the return direction from the thermal head 22 when the thermal recording is performed by the thermal head 22. For this reason, the conveyance speed of the color thermal recording paper 11 is set in accordance with the thermal recording speed.

  As the LED of the M lamp 26, an ultraviolet LED having an emission wavelength peak at about 380 nm is used. The light fixing by the M lamp 26 is performed while the recording area where the M fixing by the YM lamp 24 has been completed is conveyed in the feeding direction for the recording of the next cyan image. Since thermal recording is not performed in the M fixing in the feeding direction, the conveyance speed of the color thermal recording paper 11 can be adjusted according to the illuminance of the M lamp 26.

  Further, while the transport direction is reversed in the return direction and the head of the recording area is sent toward the thermal head 22, the M lamp 26 is kept on and M fixing is performed.

  A cutter 32 is disposed downstream of the M lamp 26 in the feed direction. The recording area where the thermal recording and the light fixing are completed is cut into one sheet by the cutter 32. The cut sheet is discharged out of the printer from a discharge port 33a formed in the case 33 of the printer 10.

  The operation of the above configuration will be described below with reference to the flowchart shown in FIG. When a print instruction is given, the paper feed roller 13 rotates and the color thermal recording paper 11 is fed to the transport path. The color thermal recording paper 11 is conveyed in the feeding direction by the conveying roller pair 14. The conveyance in the feeding direction is continued until the running section is secured even after the recording area passes through the thermal head 22. When the recording area is sent to a predetermined position, the drive motor 15 rotates in the reverse direction and the color thermal recording paper 11 is conveyed in the returning direction. At the same time when the conveyance is started, the yellow lamp 24 is also turned on. When the run-up is completed and the recording start position of the recording area reaches the thermal head 22, thermal recording of the yellow image is started.

  The recorded portion where the yellow image is recorded is sequentially sent to the YM lamp 24 and Y-fixing is performed. Since the short wavelength cut filter 28 is disposed between the YM lamp 24 and the conveyance path, the magenta fixing light out of the light emitted from the YM lamp 24 is cut, and the yellow fixing light transmitted through the filter 28 is emitted. Irradiate the recording area.

  When the end of the recording area passes through the YM lamp 24, the conveyance direction is reversed and the recording area is conveyed in the feeding direction. Even during this conveyance, the lamp 24 is lit until the recording area passes through the YM lamp 24, and Y-fixing is continued. When the recording area passes through the YM lamp 24, the YM lamp 24 is turned off once.

  When the recording area passes through the thermal head and is sent to a predetermined position, the transport direction is reversed and transport in the second return direction is performed. When the conveyance starts, the YM lamp 24 is turned on again, and the short wavelength cut filter 28 moves to the retracted position. When the run is finished and the recording area reaches the thermal head 22, thermal recording of the magenta image is started. The recorded portion where the magenta image is recorded is sequentially M-fixed by the YM lamp 24. Since the short wavelength cut filter 28 is in the retracted position, all of the light emitted from the YM lamp 24 is applied to the recording area. Even if Y fixing light is irradiated during M fixing, there is no problem because the recording and fixing of the Y thermosensitive coloring layer has already been completed.

  When the recording area passes through the YM lamp 24, the conveyance direction is reversed again, and the recording area is conveyed in the feeding direction. At the same time, the M lamp 26 starts to light. Even during this conveyance, the lamp 24 is lit until the recording area passes through the YM lamp 24, and M fixing by the YM lamp 24 is continued. When the recording area passes through the YM lamp 24, the YM lamp 24 is turned off. Further, the recording area is sent and passes through the thermal head 22. Then, the light enters the irradiation area of the M lamp 26 and M fixing by the M lamp 26 is performed. Since thermal recording is not performed during conveyance in the feeding direction, the conveyance speed of the recording area is adjusted in accordance with the illuminance of the M lamp 26.

  Even after passing through the thermal head 22, the recording area is sent until it passes through the M lamp 26. The transport amount is the transport amount necessary to secure the run-up section, that is, whether or not M fixing is performed. Regardless of the amount of conveyance required, the amount of conveyance does not increase wastefully compared to the conventional case. When the recording area passes through the M lamp 26, the transport direction is reversed, and transport in the third return direction is started. Then, when the recording area travels in the run-up section and the recording start position reaches the thermal head 22, recording of a cyan image is started. Even after the recording of this cyan image is started, the M lamp 26 is lit, so that the M fixing is continued for the recording area that has not reached the thermal head 22.

  When the cyan image recording is completed, the recording area is sent to the cutter 32. Then, the sheet is cut by the cutter 32 and discharged from the sheet discharge outlet 33a as a single sheet.

  As described above, since the M fixing is performed using two lamps, the illuminance of each lamp can be suppressed as compared with a case where a necessary amount of fixing light is obtained with one lamp. This alleviates cost and heat generation concerns. Further, since the YM lamp is used, the Y fixing and M fixing conveyance distances are equalized, and the fixing time is shortened.

1 is a configuration diagram illustrating an outline of a color thermal printer. FIG. It is a graph of the spectral characteristic of LED, and the transmittance | permeability of a short wavelength cut filter. 6 is a flowchart illustrating a printing procedure.

Explanation of symbols

10 Color Thermal Printer 11 Color Thermal Recording Paper 21 Controller 22 Thermal Head 24 YM Lamp 26 M Lamp

Claims (1)

On the support, heat sensitive color layers of Y, M, and C, which color each color of yellow, magenta, and cyan in order from the top layer, are layered, and at least each of the heat sensitive color layers of Y and M has a specific wavelength range. Using color thermal recording paper having photofixability to each of Y and M fixing light,
During the first conveyance of the color thermosensitive recording paper in the first direction, the Y image is thermally recorded on the Y thermosensitive coloring layer by the thermal head, and the recording area is arranged on the downstream side in the first direction of the thermal head. The YM light source emits both Y and M fixing light to a YM light source, and a filter for cutting the M fixing light is inserted between the YM light source and the conveyance path, and the YM light source is used for the recording area. Y recording and Y fixing steps for fixing a Y image by irradiating Y fixing light transmitted through the filter;
After the recording area is transported in the second direction opposite to the first direction and returned to the thermal head, the M image is thermally recorded on the M thermosensitive coloring layer during the second transport in the first direction. At the same time, the recording area is sent to the YM light source, and the M thermosensitive coloring layer is photofixed by irradiating the recording area with M fixing light with the YM light source retracted from the insertion position. M recording and M fixing steps;
During the second conveyance of the recording area in the second direction, the M thermosensitive coloring layer is photofixed by an M light source disposed upstream of the thermal head in the first direction and emitting the M fixing light. A fixing step;
A color thermal printing method comprising: a C recording step of thermally recording a C image on a C thermosensitive coloring layer during the third conveyance in the first direction.

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