JP3724778B2 - Color thermal printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color thermal printer that thermally records a full-color image on a color thermal recording paper. More specifically, the present invention relates to an ultraviolet lamp that is provided in the printer and that performs light fixing by irradiating the color thermal recording paper with ultraviolet rays. It is about improvement.
[0002]
[Prior art]
Using a color thermosensitive recording paper (hereinafter referred to as recording paper) in which at least three types of thermosensitive coloring layers, for example, a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer are sequentially formed on a support, a full color is used. Color thermal printers that print images are known. In this printer, a thermal head is pressed against a recording paper at the time of printing, a yellow image is thermally recorded on the yellow thermosensitive coloring layer having the highest thermal sensitivity, and immediately thereafter, the yellow thermosensitive coloring layer is irradiated with ultraviolet rays for photofixing. Next, after a magenta image is thermally recorded on the magenta thermosensitive coloring layer, it is fixed by irradiation with ultraviolet rays. Finally, a full color image is obtained by thermally recording a cyan image on the cyan thermosensitive coloring layer.
[0003]
In a color thermal printer, a conveyance roller pair for conveying recording paper, a thermal head, and an optical fixing device for irradiating ultraviolet rays are arranged along the paper supply / discharge direction (sub-scanning direction). In the printing process, the recording paper is conveyed in the paper supply / discharge direction by the conveying roller pair, and thermal recording is performed line by line in the width direction (main scanning direction) of the recording paper by the thermal head during the conveyance. As the optical fixing device, a straight tube type ultraviolet lamp is generally used, and the longitudinal direction of the straight tube is arranged along the main scanning direction.
[0004]
[Problems to be solved by the invention]
As shown in FIG. 7, a straight tube type ultraviolet lamp 81 is composed of a rod-shaped glass tube 82 and bases 83 and 84 having electrodes provided at both ends thereof. The distribution of the emission intensity of the ultraviolet lamp 81 is lowest at both ends and highest at the middle portion. Since the light amount is insufficient at both ends, an ultraviolet lamp 81 that is sufficiently longer than the width of the color thermosensitive recording paper 86 is used, and both ends with low light emission intensity of the lamp protrude from the edge of the recording paper 86. Arranged. However, the ultraviolet lamp 81 can obtain a substantially uniform integrated light quantity in the width direction of the recording paper 86. However, since a long ultraviolet lamp must be used, the lateral width of the color thermal printer becomes large.
[0005]
Further, since the light emission intensity at the center is stronger than at both ends, the cumulative amount of ultraviolet light received during movement of the color thermal recording paper 86 is small at the edge of the recording paper 86 and large at the center. As a result, uneven fixing occurs in the width direction of the color thermal recording paper 86.
[0006]
The present invention has been made to solve the above-described problems, and an object thereof is to enable uniform light fixing by using an ultraviolet lamp having a size substantially the same as the width of a recording paper.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the color thermal printer according to the present invention uses a color thermal recording paper in which a plurality of thermal coloring layers are provided on a support, and each thermal coloring layer is moved while moving the color thermal recording paper. In a color thermal printer having a thermal head for performing thermal recording and an ultraviolet lamp for performing light fixing by irradiating each thermally developed color developing layer with ultraviolet rays, the ultraviolet lamp has a glass tube on one base. The both ends of the glass tube are endless, and the base and the intermediate portion of the glass tube are disposed so as to be positioned at the center in the width direction of the color thermal recording paper.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The color thermal printer 2 shown in FIG. 2 has a paper feeding unit 6 and a printing unit 7. A recording paper roll 4 in which a long color thermal recording paper (hereinafter referred to as recording paper) 3 is wound in a roll shape is set in the paper supply unit 6.
[0009]
As is well known, the recording paper 3 has a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer sequentially provided on a support. The yellow thermosensitive coloring layer, which is the uppermost layer, has high thermal sensitivity and develops yellow with a small amount of heat energy. The cyan thermosensitive coloring layer, which is the lowermost layer, has the lowest thermal sensitivity and develops cyan when large heat energy is applied. The recording paper 3 is fed to the printing unit 7 by driving the recording paper roll 4 by the motor 8.
[0010]
The printing unit 7 heats the printing paper to emit light from each thermosensitive coloring layer, the platen rollers 13 to 16 that support the recording paper 3 facing the thermal heads 9 to 12, and the recording A pair of conveying rollers 17 to 20 that convey the paper 3, a yellow light fixing device 21 that emits near-ultraviolet light of 420 nm, and a magenta light fixing device 22 that emits near-ultraviolet light of 365 nm.
[0011]
The conveyance roller pairs 17 to 20 nip the conveyed recording paper 3 and convey it in the sub-scanning direction. During this conveyance, the recording paper 3 sequentially passes through the thermal heads 9 to 12 and the optical fixing devices 21 and 22, and printing processing is performed. The recording paper 3 for which the printing process has been completed is cut into a predetermined size by a cutter (not shown) and discharged outside the printer 2.
[0012]
Each of the thermal heads 9 to 12 is provided with a heating element array 9a to 12a in which a large number of heating elements are arranged in a line. The heating element arrays 9 a to 12 a are arranged along the width direction (main scanning direction) of the recording paper 3. Thermal recording is performed line by line along this direction.
[0013]
The thermal heads 9 to 12 are for yellow heat sensitive layer color development, magenta heat sensitive layer color development, and cyan heat sensitive layer color development in order from the paper supply side. The heat generation energy is lowest in the yellow thermal head 9 and highest in the cyan thermal head 12. A full-color image is obtained by three-color surface sequential thermal recording of the thermal heads 9 to 12.
[0014]
The yellow light fixing device 21 is disposed downstream of the yellow thermal head 9, and the magenta light fixing device is disposed downstream of the magenta thermal head 11. Photofixing is performed on the yellow thermosensitive coloring layer and the magenta thermosensitive coloring layer every time thermal recording is performed by the thermal heads 9 and 11. The cyan thermosensitive coloring layer is located in the lowermost layer of the thermosensitive layer and does not cause color mixing during recording, so that light fixing is not performed. Of course, the cyan thermosensitive coloring layer may be given photofixability.
[0015]
Each of the fixing devices 21 and 22 includes endless UV lamps 23 and 24 and reflectors 26 and 27. As shown in FIG. 1, the ultraviolet lamps 23 and 24 include glass tubes 28 and 29 and bases 31 and 32 having electrodes provided at both ends. The glass tubes 28 and 29 are formed in a circular ring shape so as to connect both ends of the caps 31 and 32. The ultraviolet lamps 23 and 24 are arranged so that the bases 31 and 32 and the intermediate portions 28 a and 29 a are at the center in the width direction of the recording paper 3.
[0016]
The phosphor is uniformly applied to the inner peripheral surfaces of the glass tubes 28 and 29. Therefore, as shown in FIG. 7, the emission intensity of each of the ultraviolet lamps 23 and 24 is the weakest near the bases 31 and 32 and the strongest at the intermediate portions 28a and 29a. Further, the outer diameters of the ultraviolet lamps 23 and 24 substantially match the length of the recording paper 3 in the width direction, but may be slightly larger than this. It may protrude from both ends of the.
[0017]
Since the central portion of the recording paper 3 is fixed only by the intermediate portions 28a and 29a, the irradiation amount of the central portion of the recording paper 3 may be lower than both ends. In such a case, the phosphor may be applied thicker on the inner peripheral surfaces of the intermediate portions 28a and 29a than other portions. Thereby, the said irradiation amount is raised. Also, by doing this, the integrated light quantity in the width direction of the recording paper 3 is made more uniform.
[0018]
Hereinafter, the operation of the above apparatus will be described. When a print instruction is given, the recording paper roll 3 rotates via the drive motor 8 and paper is fed to the print unit 7. The fed recording paper 3 is nipped by the conveyance roller 8 and conveyed in the printing unit 7. During this transport, first, the yellow thermal head 13 performs thermal recording. During this thermal recording, the ultraviolet lamp 28 of the yellow light fixing unit 21 is turned on to perform light fixing of the yellow thermosensitive coloring layer.
[0019]
The central portion of the recording paper 3 receives weak ultraviolet light near the base 31 by the yellow ultraviolet lamp 23 and strong light from the intermediate portion 28a. On the other hand, both end portions of the recording paper 3 receive ultraviolet rays having a moderate light emission intensity almost uniformly. For this reason, as shown in FIG. 3, the integrated light quantity of the ultraviolet rays received by the recording paper 3 during conveyance is substantially uniform in the width direction. As a result, fixing unevenness is eliminated.
[0020]
When the thermal recording and the light fixing of the yellow thermosensitive coloring layer are completed, the thermal recording is then performed by the magenta thermal head 11 and then the light fixing is performed by the magenta optical fixing device 22. Similar to the yellow light fixing device 21, the magenta thermosensitive coloring layer is also light-fixed without fixing unevenness.
[0021]
When the thermal recording and photofixing of the magenta thermosensitive coloring layer are completed, the cyan thermal head 12 performs thermal recording of the cyan thermosensitive coloring layer. The printed recording paper 3 on which the full-color image is recorded is cut into a predetermined size and discharged out of the printer 2.
[0022]
The shape of the ultraviolet lamp may be, for example, an ellipse, a rectangle, an ellipse or the like in addition to a circle. FIG. 4 shows a color thermal printer using oval ultraviolet lamps 41 and 42. FIG. 5 shows a color thermal printer using rectangular ultraviolet lamps 46 and 47. 4 and 5, the same members as those in the embodiment shown in FIG.
[0023]
In addition, each of the above embodiments is a so-called three-head one-pass printer, but the present invention can also be implemented in a one-head three-pass printer. In this case, as shown in FIG. 6, when the ultraviolet lamp 66 is arranged inside the ultraviolet lamp 67 to form a double structure, the two ultraviolet lamps 66 and 67 are arranged side by side. The length of the color thermal printer in the sub-scanning direction can be reduced.
[0024]
In FIG. 6, the printer 61 is provided with a thermal head 62, a platen roller 63, a conveying roller pair 64, a yellow ultraviolet lamp 66, and a magenta ultraviolet lamp 67. The thermal head 62 heats the recording paper 3 with thermal energy corresponding to each thermal coloring layer, and selectively develops each thermal coloring layer.
[0025]
The printer 61 performs thermal recording and light fixing while moving the print sheet alternately in the forward direction from the paper feed side to the paper discharge side and in the reverse direction from the paper discharge side to the paper feed side by the transport roller pair 64. When the recording paper 3 is moved in the forward direction, the thermal head 62 performs color recording in the order of yellow, magenta, and cyan. When the recording paper 3 is moved in the reverse direction, light fixing is performed by the ultraviolet lamp 66 in the yellow thermosensitive coloring layer and by the ultraviolet lamp 67 in the magenta thermosensitive coloring layer.
[0026]
The magenta ultraviolet lamp 67 is disposed inside the yellow ultraviolet lamp 66, but conversely, the yellow ultraviolet lamp 66 may be disposed inside the magenta ultraviolet lamp 67.
[0027]
【The invention's effect】
As described above in detail, in the color thermal printer of the present invention, an endless ultraviolet lamp in which both ends of a glass tube are attached to a single base, the intermediate portion between the base and the glass tube is made of color thermal recording paper. Since it is arranged so as to be positioned at the center in the width direction, it is possible to perform uniform light fixing in the width direction of the recording paper. Further, since the ultraviolet lamp has the same size as the color thermal recording paper, the color thermal printer can be miniaturized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a printer using a circular ultraviolet lamp.
FIG. 2 is an explanatory diagram showing an outline of a printer of the present invention.
FIG. 3 is a graph showing a cumulative amount of light in a width direction received by a recording sheet from a circular ultraviolet lamp and the ultraviolet lamp.
FIG. 4 is an explanatory diagram showing a printer using an oval ultraviolet lamp.
FIG. 5 is an explanatory diagram showing a printer using a rectangular ultraviolet lamp.
FIG. 6 is an explanatory diagram showing a printer having a double structure of a rectangular ultraviolet lamp.
FIG. 7 is a graph showing a straight tube ultraviolet lamp, emission intensity of the ultraviolet lamp, and integrated light quantity in the width direction received by the recording paper from the lamp.
[Explanation of symbols]
2 Color thermal printer 3 Recording paper 23, 24, 41, 42, 43, 44, 66, 67 UV lamp 31, 32 Base 28, 29 Glass tube

Claims (5)

Using a color thermal recording paper in which a plurality of thermal coloring layers are layered on a support, a thermal head that performs thermal recording on each thermal coloring layer while moving the color thermal recording paper, and each thermal recorded thermal recording paper In a color thermal printer having an ultraviolet lamp that performs light fixing by irradiating the coloring layer with ultraviolet rays,
The ultraviolet lamp has an endless shape in which both ends of a glass tube are attached to a single base, and the base and an intermediate portion of the glass tube are disposed so as to be positioned at the center in the width direction of the color thermal recording paper. A color thermal printer. 2. The color thermal printer according to claim 1, wherein the size of the ultraviolet lamp is substantially the same as the width of the color thermal recording paper. 3. The color thermal printer according to claim 1, wherein the endless shape is any one of a circle, an ellipse, an oval, and a rectangle. The color thermosensitive recording paper is composed of first to third thermosensitive color-developing layers that are color-coded and recorded in order. 4. The color thermal printer according to claim 1, wherein ultraviolet lamps are used, and one of the ultraviolet lamps is disposed inside the other. The color thermal printer according to any one of claims 1 to 4, wherein the phosphor is applied to an intermediate portion of the glass tube to be thicker than other portions.

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