JP2004001305A - Thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal printer in which noncontact cleaning of a thermal head is carried out. <P>SOLUTION: A photocatalyst layer is provided on the surface of the light emitting element in the thermal head 2. A lighting window 14 and a movable light shielding plate 17 are provided in a case 8. The light shielding plate 17 opens/closes the lighting window 14. The lighting window 14 is closed when printing is carried out and opened when printing is not carried out. The photocatalyst layer of the thermal head 2 located at a retreat position is irradiated with external light 9 from the lighting window 14. When the photocatalyst layer is irradiated with a light beam, organic components adhering to the surface thereof is subjected to photolysis. Consequently, the thermal head 2 can be cleaned. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal printer capable of cleaning dirt attached to the surface of a thermal head.
[0002]
[Prior art]
A thermal printer of a thermal recording system (hereinafter referred to as a color thermal printer) that records and records a full color image by heating a color thermal recording paper is manufactured and sold by the present applicant. In the color thermal recording paper, a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer are sequentially provided on a support, and a transparent protective layer is provided on the yellow thermosensitive coloring layer. The yellow thermosensitive coloring layer has the highest thermal sensitivity, and the lowermost cyan thermosensitive coloring layer has the lowest thermal sensitivity.
[0003]
The color thermal printer includes a thermal head in which a number of heating elements are arranged in the main scanning direction. The color thermal printer performs thermal recording by pressing the heating element against color thermal recording paper and heating the recording paper to develop a color. Thermal recording is performed from the yellow thermosensitive coloring layer having the highest thermal sensitivity, and a yellow image, a magenta image, and a cyan image are recorded in the order of frames to print a full color image. In the color thermosensitive recording paper, the yellow image and the magenta image are light-fixed by a fixing lamp so that the recorded thermosensitive coloring layer does not color again. In this light fixing, near ultraviolet rays having an emission peak of 420 nm are used for yellow images, and ultraviolet rays having an emission peak of 365 nm are used for magenta images.
[0004]
When the color thermosensitive recording paper is heated, the protective layer is softened and the organic components are dissolved. And this organic component adheres to the surface of a heat generating element as dirt. Since this dirt hinders heat transfer and deteriorates the print image quality, it is necessary to clean the thermal head. As a conventional cleaning method, there is a method using a cleaning sheet having an abrasive layer. That is, the cleaning sheet is passed between the thermal head and the platen roller, and the dirt on the surface of the light emitting element is polished and removed.
[0005]
[Problems to be solved by the invention]
However, in the conventional cleaning method, since the surface of the heat generating element is polished with a cleaning sheet having a polishing layer, there is a problem that the surface of the thermal head is worn by the polishing and print quality is deteriorated.
[0006]
The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a thermal printer that can perform head cleaning without using a cleaning sheet that contacts the thermal head.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the thermal printer of the present invention is a thermal printer provided with a thermal head for recording color by heating a thermal recording paper in the printer body. The thermal head includes a surface of the heating element. In addition, a photocatalyst layer is provided for removing dirt adhering to the surface by reacting with light, and the printer main body is for taking in external light to be irradiated to the photocatalyst layer when printing is not performed. A lighting window and a light shielding plate for opening and closing the lighting window are provided.
[0008]
A condensing member that condenses external light may be disposed in the vicinity of the daylighting window. Moreover, it is preferable to use titanium oxide for the photocatalyst layer.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2, a discharge port 10, a power button 11, and a print button 12 are provided on the front surface of the case 8 of the color thermal printer 1. A loading port for attaching and detaching the recording paper magazine is formed on the side surface. The loading port is covered with a lid 13 that is attached to be freely opened and closed. A lighting window 14 is formed on the upper surface. As will be described later, the daylighting window 14 is for taking in external light for cleaning the thermal head.
[0010]
In the case 8, a thermal head 2, a platen roller 3, an optical fixing device 5, a paper feed roller pair 6, a paper discharge roller pair 7, and a recording paper magazine 15 are provided. The case 8 is formed of a light-shielding material such as colored plastic so that the recording paper is not exposed to outside light.
[0011]
The recording paper magazine 15 accommodates a recording paper roll 4 in which a long color thermal recording paper 4a is wound in a roll shape. The recording paper magazine 15 is made of a light-shielding material, for example, colored plastic so that the recording paper roll 4 is not exposed to external light. Instead of the recording paper roll, recording paper that has been cut into a predetermined size sheet in advance may be used.
[0012]
The paper feed roller pair 6 is driven by a motor 61. The paper feed roller pair 6 nips the color thermal recording paper 4 a during paper feeding, pulls it out from the recording paper roll 4, and feeds it toward the thermal head 2. At the time of rewinding, it is conveyed toward the recording paper roll 4. Similarly, the paper discharge roller pair 7 is driven by a motor 71 to convey the color thermal recording paper 4a in the paper feeding direction and the rewinding direction. The platen roller 3 is driven and rotated by the pair of paper feed rollers 6 and the pair of paper discharge rollers 7 by friction with the color thermal recording paper 4a being conveyed.
[0013]
The optical fixing unit 5 includes a yellow fixing lamp, magenta fixing lamps 5a and 5b, and a reflection plate 5c. The yellow fixing lamp 5a emits near-ultraviolet light having a light emission wavelength peak around 420 nm to lightly fix the yellow image. The magenta fixing lamp 5b radiates ultraviolet rays having a light emission wavelength peak around 365 nm to photofix the magenta image.
[0014]
As shown in FIG. 3, the color thermosensitive recording paper 4a has a cyan thermosensitive coloring layer 21, a magenta thermosensitive coloring layer 22, a yellow thermosensitive coloring layer 23, and a transparent protective layer 24 laminated in this order on a transparent or white support 20. Has a structure. The yellow thermosensitive coloring layer 23 loses its coloring ability due to near ultraviolet rays of the yellow fixing lamp 5a, and the magenta thermosensitive coloring layer 22 loses its coloring ability due to ultraviolet rays of the magenta fixing lamp 5b.
[0015]
The thermal head 2 is provided so as to be movable between a printing position where the thermal head 2 is pressed against the color thermal recording paper 4 on the platen roller 3 and a retracted position away from the platen roller 3.
[0016]
In the thermal head 2, a partial glaze layer 31 having a circular arc cross section is formed on an alumina substrate 30. On the partial glaze layer 31, the heat generating body 32 which comprises a heat generating element, and the electrode 33 are provided, and the protective layer 34 is laminated | stacked on it. Many heating elements 32 are arranged in the main scanning direction. A photocatalytic layer 35 is provided on the protective layer 34. When the photocatalyst layer 35 is irradiated with light, organic substances adhering to the surface of the photocatalyst layer 35 are photolyzed into gaseous components such as water and carbon dioxide and diffused into the air. For example, titanium oxide is used as the photocatalyst layer.
[0017]
The daylighting window 14 takes in external light 9 that irradiates the photocatalytic layer 35. A transparent member 16 is fitted in the daylighting window 14 to prevent dust and dirt from entering the case 8 from the outside.
[0018]
The light shielding plate 17 is provided so as to be movable between an open position where the daylighting window 14 is opened and a closed position where the daylighting window 14 is closed. When the light shielding plate 17 is in the open position, external light 9 enters from the daylighting window 14. This external light 9 is applied to the surface of the heating element of the thermal head 2 in the retracted position. When the light shielding plate 17 is in the closed position, the inside of the case 8 is shielded from light. A knob 18 is formed integrally with the light shielding plate 17, and the knob 18 is exposed to the outside of the case 8. The daylighting window 14 is opened and closed by manually sliding the knob 18.
[0019]
The user can clean the thermal head 2 by opening the daylighting window 14 when printing is not performed. When performing printing, the daylighting window 14 is closed and the inside of the case 8 is shielded from light.
[0020]
If printing is started with the daylighting window 14 opened, the color thermal recording paper 4a is exposed. Therefore, the sensor 19 detects the position of the light shielding plate 17. The sensor 19 sends a signal to the control unit when the light shielding plate 17 is in the closed position. The control unit determines the position of the light shielding plate 16 based on this signal. When the light shielding plate 17 is in the open position, printing is prohibited. For example, a photo sensor is used as the sensor 19. Note that the printer may not be turned on when the daylighting window 14 is open. Further, when printing is started with the daylighting window 14 open, a warning may be issued to inform the user that the daylighting window 14 is open.
[0021]
Next, the operation of the present invention will be described. When performing printing, the user confirms that the daylighting window 14 is closed. If it is open, it is closed and then the print button 12 is pressed to instruct printing start. Even if a print start instruction is given with the daylighting window 14 open, printing is not started, and the color thermal recording paper 4a is not accidentally exposed.
[0022]
When the printing process is started, the color thermal recording paper 4 a is fed toward the thermal head 2 by the paper feed roller pair 6. The leading edge of the color thermal recording paper 4a is further conveyed in the paper feeding direction after passing through the platen roller 3. When the color thermal recording paper 4a is conveyed by one sheet and the rear end of the recording area comes to the position of the thermal head 2, the conveyance is stopped. The thermal head 2 moves, and the color thermal recording paper 4a comes into pressure contact with the heating element array.
[0023]
The color thermal recording paper 4a is conveyed in the rewind direction. The thermal head 2 is driven in synchronism with the conveyance of the recording paper, and a yellow image is recorded line by line. When the area where the yellow image is recorded comes below the yellow fixing lamp 5a, the yellow fixing lamp 5a is turned on and the yellow image is fixed. When the yellow image recording and the light fixing are completed, the thermal head 2 is retracted.
[0024]
The color thermal recording paper 4a is conveyed in the paper feeding direction. When the conveyance is completed, the thermal head 2 moves to the printing position, and a magenta image is recorded in synchronization with the pulling back of the color thermal recording paper 4a. The magenta fixing lamp 5b is turned on, the ultraviolet ray is irradiated to the area where the magenta image is recorded, and the magenta image is optically fixed.
[0025]
Similarly, the color thermal recording paper 4a is conveyed in the paper feeding direction and then in the rewinding direction, and a cyan image is recorded during this conveyance. When recording yellow, magenta, and cyan images, the color thermal recording paper 4a is heated to a high temperature. As each image is recorded, the transparent protective layer 24 softens, and a part of the transparent protective layer 24 adheres to the photocatalytic layer 35 on the head surface.
[0026]
When the recording of each image is completed, the color thermal recording paper 4a is conveyed in the paper feeding direction by the paper ejection roller pair 7 for paper ejection. In the color thermal recording paper 4a, the printed portion of the image is cut off by a cutter (not shown). After the paper discharge, the unrecorded portion is rewound and accommodated in the recording paper magazine 15. When the number of prints is plural, the above operation is repeated.
[0027]
When printing is completed, the user opens the daylighting window 14. When the daylighting window 14 is opened, external light 9 enters the color thermal printer 1 and is irradiated on the surface of the heating element of the thermal head 2. By irradiation with the external light 9, the photocatalyst layer 35 reacts and the organic component of the transparent protective layer 24 adhering during recording is photolyzed. The decomposed organic components are decomposed into water and carbon dioxide and diffused into the air. When printing is completed, the color thermal recording paper 4a is accommodated in the recording paper magazine 15, so that it is not exposed by the incident external light 9.
[0028]
As a light source used for cleaning the thermal head, it is conceivable to use fixing light from a fixing lamp instead of taking in external light. However, this requires power for lighting the fixing lamp. Since the present invention uses external light, it is more energy efficient than cleaning using a fixing lamp.
[0029]
As in the color thermal printer 40 shown in FIG. 4, a lens 41 that is a condensing member may be disposed below the transparent top plate 16. In addition, the same code | symbol is used about the same member as embodiment mentioned above. In this example, since the external light 9 is collected by arranging the lens 41, the amount of the external light 9 applied to the thermal head 2 increases. Thereby, the cleaning time of the thermal head 2 can be shortened.
[0030]
Depending on the structure of the printer, it may be possible that external light cannot be directly applied to the thermal head. In this case, in order to irradiate the thermal head with a sufficient amount of external light, a light guide means including a single plane mirror, a concave mirror, or an optical fiber or a combination of several types may be used and guided to the thermal head.
[0031]
In the above embodiment, the color thermal printer is described as an example, but a monochrome thermal printer may be used. Further, although an example of a printer that records on a plurality of thermosensitive coloring layers with one head has been described, a printer having a thermal head for each color may be used. In this case, a lighting window may be provided for each thermal head, or external light collected from one lighting window may be guided to each thermal head by a light guide.
[0032]
Moreover, in the said embodiment, although the movement means of the light-shielding plate is performed manually, you may provide a drive motor and may be moved automatically. In this case, in conjunction with the power button, it is desirable to automatically open the daylighting window and start cleaning when the power is turned off. The lighting window is automatically closed when the power is turned on.
[0033]
In addition to interlocking with the power supply, cleaning may be performed every time one printing process is completed, or automatically when a predetermined number of prints have been completed or when a predetermined time has elapsed. Alternatively, the daylighting window may be opened and cleaned.
[0034]
In the above description, the protective layer and the photocatalyst layer are separately provided on the heating element array. However, the protective layer may be formed of a substance that performs photocatalytic action. By so doing, the thickness of the layer can be reduced, so that the heat transfer efficiency from the heating element to the recording material can be increased compared to the case where the protective layer and the photocatalyst layer are provided separately.
[0035]
Furthermore, the present invention has been described by taking a thermal recording system thermal printer using thermal recording paper as an example of the thermal printer, but is not limited to this, and the ink on the film is melted or sublimated and transferred to the recording paper. The present invention can also be applied to a thermal transfer type thermal printer.
[0036]
【The invention's effect】
According to the color thermal printer of the present invention, since the thermal head having the photocatalyst layer provided on the surface of the heat generating element is used, the deposits can be removed only by irradiating light. In addition, since a lighting window is provided in the case so that external light can be used, a special light source for irradiating the thermal head is not required. As described above, the head can be cleaned without using the cleaning sheet, and the thermal head is not worn. In addition, since the heat generating element is irradiated with external light without using a special light source, consumption of heat energy during thermal head cleaning can be suppressed.
[Brief description of the drawings]
FIG. 1 is a perspective view of the appearance of a thermal printer according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a thermal printer according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view showing the structure of a thermal head and color thermal recording paper.
FIG. 4 is a schematic configuration diagram of a thermal printer according to another embodiment of the present invention.
[Explanation of symbols]
1,40 Color thermal printer 2 Thermal head 4a Color thermal recording paper 5 Optical fixing device 8 Case 9 External light 14 Daylighting window 17 Light shielding plate 35 Photocatalyst layer

Claims (3)

In a thermal printer equipped with a thermal head that records color by heating a thermal recording paper in the printer body,
The thermal head is provided with a photocatalyst layer on the surface of the heat generating element for removing dirt adhered to the surface by reacting with light, and the printer main body includes the photocatalyst layer when printing is not performed. A thermal printer comprising: a daylighting window for taking in external light to be irradiated onto the photocatalyst layer; and a light shielding plate for opening and closing the daylighting window. The thermal printer according to claim 1, wherein a condensing member for condensing external light is disposed in the vicinity of the daylighting window. The thermal printer according to claim 1, wherein the photocatalyst layer is titanium oxide.

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