JP2003231282A - Thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fixing performance and to reduce the size of a printer. <P>SOLUTION: Each fluorescent lamp 11 is provided such that a center of an opening section 34 is positioned on a perpendicular 40 from the center of the fluorescent lamp 11 to a recording paper 3. Ultraviolet light emitted from each fluorescent lamp 11 represents a high luminance over a wide range in a sub-scanning direction on a thermal coloring layer shown in a characteristic curve A. As a result, it is possible to reduce a conveyance distance and to raise the fixing speed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer provided with a photo-fixing device, and more particularly to a thermal printer provided with a fluorescent lamp having an opening through which an electromagnetic ray for photo-fixing is emitted.

[0002]

2. Description of the Related Art A color thermosensitive recording paper (hereinafter referred to as recording paper) is used in which a plurality of thermosensitive coloring layers, for example, a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer and a yellow thermosensitive coloring layer are sequentially laminated on a support. Thermal printers for printing full-color images are known. Usually, the yellow thermosensitive coloring layer and the magenta thermosensitive coloring layer are composed of a diazonium salt compound and a coupler which reacts with this to develop a color. The diazonium salt compound is photolyzed by irradiation with electromagnetic rays, for example, ultraviolet rays. Due to this photodecomposition, the coupler cannot react thermally, and the coloring ability of the unrecorded portion of each thermosensitive coloring layer disappears. As is well known, this phenomenon is called light fixing. The cyan thermosensitive coloring layer contains an electron-donating dye precursor and an electron-accepting compound as main components, and develops a cyan color when heated.

A thermal recording type thermal printer comprises a pair of conveying rollers for conveying a recording sheet, a thermal head for heating the recording sheet to develop a color, and an optical fixing device having a light source for irradiating ultraviolet rays. The thermal head and the optical fixing device are arranged along the conveyance direction (sub-scanning direction) of the recording paper. The thermal head performs thermal recording line by line in the width direction (main scanning direction) of the recording paper while the recording paper is being conveyed. When the thermal recording is completed, the recorded recording paper is conveyed to the optical fixing device and is optically fixed.

In the printing process, first, a thermal head is pressed against a recording paper to thermally record a yellow image on the yellow thermosensitive coloring layer having the highest thermal sensitivity, and immediately after that, a near-ultraviolet ray having an emission peak of about 420 nm is emitted by an optical fixing device. To heat-fix the yellow thermosensitive coloring layer. Next, a magenta image is thermally recorded on the magenta thermosensitive coloring layer, and then the magenta thermosensitive coloring layer is optically fixed by irradiating ultraviolet rays having an emission peak of about 365 nm. Finally, a cyan image is thermally recorded on the cyan thermosensitive coloring layer to obtain a full-color image.

As the light source of the optical fixing device, for example, a cylindrical fluorescent lamp is used, and two types of lamps, a yellow image fixing lamp and a magenta image fixing lamp, are provided along the conveying direction of the recording paper. The inside of these fluorescent lamps is coated with a phosphor that emits ultraviolet rays having a specific wavelength range described above. The illuminance distribution on the peripheral surface of such a fluorescent lamp is uniform over the entire circumference.

On the other hand, in contrast to the fluorescent lamp whose illuminance distribution is uniform over the entire circumference, a fluorescent lamp whose illuminance distribution has directivity is applied as a light source of a photo-fixing device.
A thermal printer in which the illuminance of ultraviolet rays in a specific direction is increased to improve the fixing performance of an optical fixing device is disclosed in Japanese Patent Application Laid-Open No. 07-
It is proposed from Japanese Patent No. 320692. The fluorescent lamp described in this publication forms a reflective film inside a transparent airtight container such as a cylindrical transparent glass in which a discharge gas is sealed, leaving an opening, and the fluorescent film is formed inside the reflective film. Form the body layer, so that the ultraviolet rays are emitted only from the opening,
The illuminance in a specific direction is increased.

In the optical fixing device described in the above publication, as shown in FIG. 8, two fluorescent lamps 100 are arranged in parallel along the sub-scanning direction, and the openings 101, 101 have an angle τ with respect to each other.
They are inclined in a direction facing each other with an inclination angle of = 60 °. The inclined lines of the openings 101, 101 are connected at one point P on the thermosensitive coloring layer of the recording paper 102. That is, the triangle formed by connecting the point P and the center of the fluorescent lamp 100 is arranged so as to form an equilateral triangle. The illuminance distribution characteristic of the thermosensitive coloring layer of the ultraviolet light emitted from the fluorescent lamp 100 arranged as described above shows extremely high illuminance at the central point P as shown by the curve X. Therefore, the fixing speed of the recording paper 102 can be increased, and the fixing performance of the optical fixing device can be improved.

[0008]

However, the fluorescent lamps are arranged as described above, and one of the thermosensitive coloring layers of the recording paper is used.
When only the point P is irradiated with ultraviolet rays having high illuminance, the optical path of the ultraviolet rays becomes long, so that the illuminance in the thermosensitive coloring layer is relatively lowered. For this reason, the characteristics of the fluorescent lamp having the illuminance distribution with directivity cannot be fully utilized, and the fixing speed does not dramatically increase.
Therefore, only a slight improvement in fixing performance can be expected.

Further, if both ends of the recording paper in the sub-scanning direction do not necessarily pass through the central point P, sufficient optical fixing cannot be carried out, so that the conveying distance of the recording paper becomes long and even if the fixing speed can be increased, On the contrary, the print processing time becomes slow.

Further, it is necessary to increase the size of the apparatus in the sub-scanning direction in order to secure the conveyance path of the recording paper, which causes a problem that the miniaturization of the apparatus is hindered. Further, if two fluorescent lamps are simply provided close to each other in order to shorten the transport distance of the recording paper in the above system, part of the ultraviolet rays emitted from one lamp will be blocked by the other lamp. Therefore, the illuminance will decrease.

It is an object of the present invention to provide a thermal printer in which the fixing performance of the optical fixing device is improved and the printer is downsized.

[0012]

In order to achieve the above object, the present invention provides a cylindrical translucent airtight container in which a discharge gas is sealed, a reflective film formed on the inner wall surface thereof, and Using a fluorescent lamp provided with a phosphor layer formed inside a reflective film and an opening excluding a part of the reflective film, the recording material is irradiated with electromagnetic radiation emitted from the opening. In a thermal printer equipped with a photo-fixing device for eliminating the coloring ability of the recording material, a plurality of the fluorescent lamps are used, and the opening of the opening is formed on a perpendicular line drawn from the central axis of each fluorescent lamp to the recording material. The fluorescent lamps are arranged so that the center is located.

In addition, three or more fluorescent lamps are arranged side by side along the recording material conveying direction, and the fluorescent lamps arranged at both ends are better than the fluorescent lamps arranged between them.
It is preferable to increase the spread angle of the opening from the central axis of the fluorescent lamp.

[0014]

1 is a schematic view of a thermal printer embodying the present invention. The thermal printer 2 carries out thermal recording and optical fixing of a full-color image while reciprocating the recording paper 3 in the forward and reverse directions indicated by the arrows. The thermal printer 2 includes a thermal head 4 that heats each thermosensitive coloring layer to develop a color, a platen roller 5 that faces the thermal head 4 to support the recording paper 3, and a pair of conveying rollers 6 that conveys the recording paper 3. And the optical fixing device 7.

As shown in FIG. 2, the recording paper 3 has a support 2
0, a cyan thermosensitive coloring layer 21, a magenta thermosensitive coloring layer 2
2, a yellow thermosensitive coloring layer 23, and a protective layer 24 are sequentially laminated. The thermosensitive coloring layers 21 to 23 are layered from the surface of the support 20 in the order of thermal recording.
The cyan thermosensitive coloring layer 21 contains an electron-donating dye precursor and an electron-accepting compound as main components, and develops a cyan color when heated.

The magenta thermosensitive coloring layer 22 contains a diazonium salt compound having a maximum absorption wavelength of about 365 nm and a coupler which thermally reacts with the diazonium salt compound to develop magenta color. The magenta thermosensitive coloring layer 22 is used for the thermal head 4
When a magenta image is heat-recorded by irradiation with an ultraviolet ray of about 365 nm, the diazonium salt compound is photolyzed and the coloring ability is lost.

The yellow thermosensitive coloring layer 23 contains a diazonium salt compound having a maximum absorption wavelength of about 420 nm, and a coupler which thermally reacts with this compound to develop yellow. When this yellow thermosensitive coloring layer 23 is irradiated with near-ultraviolet rays in the vicinity of 420 nm, the yellow thermosensitive coloring layer 23 is optically fixed and loses its coloring ability.

FIG. 3 shows the coloring characteristics of the thermosensitive coloring layers 21-23. The abscissa represents the thermal energy generated by the heating element, in which the yellow thermosensitive coloring layer 23 has the lowest thermal energy and the cyan thermosensitive coloring layer 21 has the highest thermal energy. The main cause of this difference in thermal energy is that the cyan thermosensitive coloring layer 21 is the yellow thermosensitive coloring layer 2
This is because heating must be performed via the magenta thermosensitive coloring layer 22.

As shown in FIG. 1, the conveyance roller pair 6 is rotated in the direction of the arrow by the drive motor 8 and nips the fed recording paper 3 to convey it in the sub-scanning direction. During this conveyance, the recording paper 3 passes through the thermal head 4 and the optical fixing device 7, and the printing process 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 is discharged to the outside of the thermal printer 2.
As the drive motor 8, for example, a pulse motor that rotates a predetermined angle each time one drive pulse is applied is used, and the carry amount of the recording paper 3 is controlled by counting the number of drive pulses.

As is well known, the thermal head 4 has a large number of heating elements arranged in a line in the main scanning direction.
Each heating element generates thermal energy corresponding to the density of the pixel to sequentially record images of yellow, magenta, and cyan colors on the thermosensitive coloring layers 21 to 23, respectively.

The photo-fixing device 7 radiates near-ultraviolet rays in the vicinity of 420 nm to photo-fix the yellow thermosensitive coloring layer 23 and the photo-fixing device 9 for yellow, which radiates ultraviolet rays in the vicinity of 365 nm to emit light in the magenta thermosensitive coloring layer 22. It comprises a magenta optical fixing device 10 for fixing. The light fixing by the respective light fixing devices 9 and 10 is performed by each of the yellow and magenta thermosensitive coloring layers 2.
It is performed after recording 3 and 22. The cyan thermosensitive coloring layer 21 is located at the lowermost layer of the thermosensitive layer, and since color mixing does not occur at the time of recording, photofixability is not provided. Of course, there is no problem even if the cyan thermosensitive coloring layer 21 is optically fixed.

The fixing device 9 for yellow has 42 as a light source.
Two fluorescent lamps 11 that emit near-ultraviolet rays near 0 nm
Is equipped with. A reflector 1 is provided around the fluorescent lamp 11.
3 is provided.

The magenta optical fixing device 10 includes two fluorescent lamps 1 as a light source, which emits ultraviolet rays having a wavelength of around 365 nm.
Equipped with 2. Similar to the yellow fixing device 9, a reflecting plate 14 is provided around the fluorescent lamp 12. The fluorescent lamps 11 and 12 have the openings 34 as will be described later, and the amount of ultraviolet rays directed to the reflecting plates 13 and 14 is small. Therefore, the reflecting plates 13 and 14 may not be provided.

As shown in FIG. 4, the tube 3 of the fluorescent lamp 11
A transparent protective film 31 is formed on the entire inner wall surface of No. 0. The tube 30 constitutes a transparent airtight container such as transparent glass, and a predetermined amount of mercury or amalgam is contained in the tube 30.
A discharge gas such as argon is enclosed. Protective film 31
Protects the discharge plasma from direct contact with the inner wall surface of the tube 30.

A reflective film 32 is formed in a predetermined range in the circumferential direction inside the translucent protective film 31, and a phosphor layer 33 is formed in a predetermined range in the circumferential direction inside the reflective film 32. There is. Since the reflective film 32 is formed in a predetermined range in the circumferential direction, a transparent light transmitting portion, that is, an opening 34 is formed in a region where the reflective film 32 is not formed. The opening 34 has a predetermined width and is formed along the axial direction of the tube 30. A spread angle of the opening 34 from the center of the fluorescent lamp 11, that is, an opening angle α is set in a range of 60 ° to 90 °, for example, 90 °.

The phosphor layer 33 is formed of a phosphor that receives ultraviolet rays emitted from mercury and converts them into ultraviolet rays having an emission peak near 420 nm. As such a phosphor, for example, a general formula (Sr, Ca) 2P2O
7: There is a halophosphate phosphor represented by Eu.

On the other hand, the fluorescent lamp 12 which is the light source of the magenta optical fixing device 10 has the same structure as the fluorescent lamp 11 shown in FIG. Phosphor layer 33 of fluorescent lamp 12
Is formed of a phosphor that receives ultraviolet rays emitted from mercury and converts them into ultraviolet rays having an emission peak near 365 nm. An example of such a phosphor is a borate phosphor represented by the general formula SrB4O7: Eu.

As shown in FIG. 5, the fluorescent lamp 11 is arranged so that the center of the opening 34 is located on the perpendicular line 40 drawn from the central axis of the fluorescent lamp 11 to the recording paper 3, and the The light path is the smallest. Fluorescent lamp 11
As shown by the characteristic curve A, the ultraviolet light emitted from the sample shows a high illuminance over a wide range in the sub-scanning direction of the thermosensitive coloring layer. Similarly, the fluorescent lamp 12, which is the light source of the magenta optical fixing device 10, also has the recording paper 3 from the center axis of the fluorescent lamp 12.
It is arranged so that the center of the opening 34 is located on the perpendicular line drawn with respect to, and the optical path of ultraviolet rays is minimized. The ultraviolet rays emitted from the fluorescent lamp 12 exhibit high illuminance over a wide range in the sub-scanning direction of the thermosensitive coloring layer.

The operation of the above configuration will be described below. When the print instruction is given, the recording paper 3 is fed,
It is transported by the transport roller pair 6. During the first transport in the forward direction, thermal recording of a yellow image by the thermal head 4 and optical fixing by the yellow optical fixing device 9 are performed on the yellow thermosensitive coloring layer 23. When the yellow image is recorded by the thermal head 4, the recorded portion of the recording paper 3 is sequentially sent to the yellow optical fixing device 9. During this recording, the fluorescent lamp 11 lights up, and the yellow thermosensitive coloring layer 2
Optical fixing is performed on No. 3.

When the thermal recording and the optical fixing of the yellow thermosensitive coloring layer 23 are completed, the conveying roller pair 6 rotates in the reverse direction and the recording paper 3
Are conveyed in the opposite direction. When the recording paper 3 returns to the position of the thermal head 4, the second transport in the forward direction is started. During this conveyance, thermal recording and optical fixing of a magenta image are performed on the magenta thermosensitive coloring layer 22. When the magenta image is recorded by the thermal head 4, the recorded portion of the recording paper 3 is sequentially sent to the magenta optical fixing device 10. During this recording, the fluorescent lamp 12 is turned on, and the magenta thermosensitive coloring layer 22 is optically fixed.

When the thermal recording and the optical fixing of the magenta image are completed, the recording paper 3 is returned to the position of the thermal head 4, and the third conveyance in the forward direction is started. A cyan image is recorded during this conveyance. When the recording of the cyan image is completed, the recording paper 3 is cut by the cutter and discharged to the outside of the thermal printer 2.

Although the recording paper 3 is conveyed flat in the above embodiment, the present invention is also applicable to the case where the recording paper is conveyed in an arc shape as shown in FIGS. 6 (A) and 6 (B). Applicable. Also in this case, as in the above-described embodiment, the fluorescent lamps 50 and 51 have the centers of the openings 56 and 57 on the perpendicular lines 54 and 55 drawn from the central axes of the fluorescent lamps 50 and 51 to the recording papers 52 and 53. Are arranged so that

In the above embodiment, the case where two fluorescent lamps are arranged has been described, but the present invention is not limited to this, and three or more fluorescent lamps may be arranged. For example,
As shown in FIG. 7, even when three fluorescent lamps are arranged, the fluorescent lamps 60 and 6 are arranged in the same manner as in the above embodiment.
1 is arranged such that the centers of the openings 65 and 66 are located on the perpendicular lines 63 and 64 drawn from the centers of the fluorescent lamps 60 and 61 to the recording paper 62. However, it is preferable to set the opening angle β of the fluorescent lamps 60 arranged at both ends to be larger than the opening angle γ of the fluorescent lamps 61 arranged between them. In this case, the area S2 in the illuminance distribution characteristic curve C when the opening angle β> γ is larger than the area S1 in the illuminance distribution characteristic curve B when the opening angle β = γ. Therefore, when the recording paper 62 is passed through the optical fixing device, the integrated value of the irradiation light amount is large, and therefore the fixing efficiency is better when the opening angle β> γ is set.

In the present invention, a fluorescent lamp having a phosphor layer in the opening may be used. Further, a plurality of fluorescent lamps may be arranged separately, or integrally formed fluorescent lamps, for example, a U-shaped tube may be used.

[0035]

As described above, according to the thermal printer of the present invention, the reflection film and the phosphor layer formed inside the cylindrical translucent airtight container in which the discharge gas is sealed, and the reflection film. Along with arranging a plurality of fluorescent lamps with an opening excluding a part of the above, place the fluorescent lamps so that the center of the opening is located on the perpendicular line drawn from the central axis of each fluorescent lamp to the recording material. Since they are arranged, the transport distance of the recording paper can be shortened and the fixing speed of the recording paper can be increased. Therefore, the fixing performance of the optical fixing device can be improved, and the printer can be downsized.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a thermal printer embodying the present invention.

FIG. 2 is a sectional view of a color thermosensitive recording paper.

FIG. 3 is a graph showing color forming characteristics of color thermosensitive recording paper.

FIG. 4 is a sectional view of a fluorescent lamp.

FIG. 5 is a diagram showing the arrangement of fluorescent lamps and illuminance distribution characteristics.

6A and 6B are diagrams showing an embodiment in which the thermal recording paper is conveyed in an arc shape in both FIGS.

FIG. 7 is a diagram showing an embodiment in which three or more fluorescent lamps are arranged.

FIG. 8 is a diagram showing an arrangement of fluorescent lamps and illuminance distribution characteristics of a conventional example.

[Explanation of symbols]

2 thermal printer 3 color thermal recording paper 4 thermal head 7 Optical fixing device 9 Yellow light fixing device 10 Magenta optical fixing device 11, 12 fluorescent lamp 21 Cyan thermosensitive coloring layer 22 Magenta thermosensitive coloring layer 23 Yellow thermosensitive coloring layer 32 reflective film 33 Phosphor layer 34 opening

Claims (2)

[Claims] 1. A cylindrical translucent airtight container in which a discharge gas is sealed, a reflective film formed on an inner wall surface of the container, a phosphor layer formed inside the reflective film, and the reflective film. A fluorescent lamp provided with an opening excluding a part of the recording material, and irradiating the recording material with electromagnetic radiation emitted from the opening to provide a thermal fixing device for erasing the coloring ability of the recording material. In the printer, a plurality of the fluorescent lamps are used, and the fluorescent lamps are arranged such that the center of the opening is located on a perpendicular line drawn from the central axis of each fluorescent lamp to the recording material. And a thermal printer. 2. Three or more of the fluorescent lamps are arranged side by side along the recording material conveyance direction, and the fluorescent lamps arranged at both ends are better than the fluorescent lamps arranged between them.
The thermal printer according to claim 1, wherein a spread angle of the opening from the central axis of the fluorescent lamp is increased.