JP2899483B2 - Optical fixing device for color thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light fixing device for a color thermal printer, and more particularly to a light fixing device capable of performing uniform light fixing.

[0002]

2. Description of the Related Art Thermal printers include a thermal printer and a thermal transfer printer. Among them, thermal printers are widely used because they can directly thermally record an image on a thermal recording material. Recently, for example, as described in JP-A-61-213169,
A color thermosensitive recording material has been proposed in which a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer are sequentially formed on a support so that a full-color image can be directly thermally recorded. This color thermosensitive recording material is
Thermal recording is performed in order from the thermosensitive coloring layer on the surface, but when performing thermal recording on the next thermosensitive coloring layer, in order to prevent thermal recording of the thermally recorded thermosensitive coloring layer on it again, The thermosensitive coloring layer is irradiated with ultraviolet rays in a wavelength range peculiar to the thermosensitive coloring layer to lose its coloring ability.

[0003]

In a conventional color thermal printer, a color thermal recording material is mounted on a platen drum, and thermal recording and optical fixing are performed while the platen drum rotates at a constant speed. The rotation speed of the platen drum during the light fixing is determined in consideration of the light emission amount of the ultraviolet lamp, but the light emission amount of the ultraviolet lamp changes according to the temperature of the tube wall of the lamp. Therefore, immediately after the start of light emission, the light emission amount is small because the tube wall temperature is low, and the light emission amount increases with time. Therefore, the amount of light emitted from the ultraviolet lamp changes depending on the point at which the color thermosensitive recording material passes through the optical fixing device, and there is a possibility that fixing unevenness occurs in one print.

The present invention has been made in view of the above circumstances, and provides a light fixing device for a color thermal printer which can maintain a constant amount of ultraviolet irradiation and perform uniform light fixing. The purpose is to:

[0005]

To achieve the above object, the present invention provides a rod-shaped ultraviolet lamp which emits ultraviolet light,
An optical fixing device is composed of a reflector having an opening formed on the side facing the color thermosensitive recording material, and a stop for opening and closing the opening of the reflector. It was done. When the amount of emitted ultraviolet light is small, the aperture is fully opened, and as the amount of emitted light increases, the aperture partially closes the opening, thereby keeping the amount of ultraviolet light irradiated on the photosensitive material constant.

According to a second aspect of the present invention, an optical fixing device monitors the amount of light emitted from an ultraviolet lamp, and adjusts the aperture of the stop according to the amount of light emitted.

According to a third aspect of the present invention, there is provided an optical fixing device for monitoring the time elapsed from the start of light emission of an ultraviolet lamp and adjusting the aperture of the stop according to the elapsed time.

[0008]

In FIG. 1, at least one portion of a sheet-like color thermosensitive recording material 11 is pressed and fixed to a platen drum 10 by a clamp member 12. During thermal recording and light fixing, the platen drum 10 is rotated at a constant speed by the pulse motor 9. Paper supply / discharge passage 13
Is provided with a pair of transport rollers 14, through which the color thermosensitive recording material 11 is transported. In this embodiment, one passage is used for both the paper supply passage and the paper discharge passage, but these may be provided separately.

On the outer periphery of the platen drum 10, a thermal head 15 is provided at a thermal recording position, and optical fixing devices 16 and 17 are provided downstream of the thermal recording position. As is well known, the thermal head 15 has a large number of heating elements arranged in a line, and generates heat at a temperature corresponding to a color to be thermally recorded and its color density. The light fixing device 16 for yellow is approximately 420 nm, and the light fixing device 17 for magenta is approximately 365 nm.
It emits ultraviolet light in the vicinity of nm.

As shown in FIGS. 2 and 3, the yellow light fixing device 16 comprises a rod-shaped ultraviolet lamp 20 and a cylindrical reflector 21 having an opening 21a formed on the side facing the color thermosensitive recording material 11. And this reflector 21
And an aperture 22 for opening and closing the opening 21a. The diaphragm 22 is composed of two diaphragm plates 23 and 24 outside the opening 21a of the reflector 21, and racks 23a and 24a are formed in a part thereof. These racks 23a and 24a are engaged with each other from both sides of the pinion 25. When the pinion 25 is rotated by the motor 26, the pair of aperture plates 23 and 24 move in the direction of approaching or moving away from each other, and adjust the size of the aperture opening. I do. A sensor 27 for monitoring the amount of light emitted from the ultraviolet lamp 20 is provided inside the aperture 22, and an output signal from the sensor 27 is sent to a controller 28. This controller 28
Controls the amount and direction of rotation of the motor 26 according to the amount of light emitted from the ultraviolet lamp 20. Since the magenta optical fixing device 17 has the same configuration, only the reference numeral is attached.

FIG. 4 shows the relationship between the elapsed time of light emission of the ultraviolet lamps 20 and 30 and the amount of light emission. Color light fixing of the heat-sensitive recording material 11, the light emission amount of ultraviolet rays is required than L _a, when the light emission amount is less than L _a, i.e. during the period from the start of light emission to T _a time the emission Insufficient amount. Therefore, after the ultraviolet lamps 20 and 30 start emitting light, the color thermosensitive recording material 11 is
As the time to reach a post-T _a time 6,17, it is set the rotational speed of the platen drum 10.

FIG. 5 shows an example of the color thermosensitive recording material 11. Cyan thermosensitive coloring layer 3 on support 35
6, magenta thermosensitive coloring layer 37, yellow thermosensitive coloring layer 3
8. A protective layer 39 is sequentially provided. These thermosensitive coloring layers 36 to 38 are provided from the surface in the order of thermal recording. For example, when thermal recording is performed in the order of magenta, yellow, and cyan, a yellow thermosensitive coloring layer and a magenta thermosensitive coloring are provided. The positions of the layers are interchanged. An intermediate layer (not shown) is provided between the layers.

The cyan thermosensitive coloring layer 36 contains an electron-donating dye precursor and an electron-accepting compound as main components, and develops cyan when heated. Magenta thermosensitive coloring layer 3
No. 7 contains a diazonium salt compound having a maximum absorption wavelength of about 365 nm and a coupler which reacts with the diazonium salt compound and develops magenta. When the magenta thermosensitive coloring layer 37 is irradiated with ultraviolet light near 365 nm after the magenta image is thermally recorded by the thermal head 15, the diazonium salt compound is photolyzed and loses its coloring ability. The yellow thermosensitive coloring layer 38 contains a diazonium salt compound having a maximum absorption wavelength of about 420 nm, and a coupler which thermally reacts with the diazonium salt compound to develop yellow. When the yellow thermosensitive coloring layer 38 is irradiated with ultraviolet light having a wavelength of about 420 nm, the yellow thermosensitive coloring layer 38 is photolyzed and loses its coloring ability. Since the cyan thermosensitive coloring layer 36 does not have the light fixing property, the irradiation of ultraviolet rays is omitted.

FIG. 6 shows the characteristics of each of the thermosensitive coloring layers 36 to 38. The thermal energy on the horizontal axis represents the thermal energy generated by the heating element of the thermal head 15, the thermal energy of the yellow thermosensitive coloring layer 38 is the lowest, and the thermal energy of the cyan thermosensitive coloring layer 36 is the highest.

Next, the operation of this embodiment will be described. At the time of paper feeding, the transport roller pair 14 applies the color thermosensitive recording material 11 supplied from a cassette (not shown) to the platen drum 1.
It is transported toward zero. When the color thermosensitive recording material 11 is set at the clamp position, the clamp member 12 presses the tip of the color thermosensitive recording material 11 against the platen drum 10 and fixes it. Thereafter, the platen drum 10 and the conveying roller pair 14 rotate, and the color thermosensitive recording material 11 is wound around the outer periphery of the platen drum 10.

Simultaneously with the start of sheet feeding, the ultraviolet lamp 20 of the yellow light fixing device 16 starts emitting light. The light emission amount of the ultraviolet lamp 20 is detected by the optical sensor 27,
The obtained light emission amount data is sent to the controller 28.
The controller 28 controls the motor 26 according to the light emission amount data.
Is determined, and a motor control signal is sent to the motor 26. In conjunction with this motor 26, the pinion 25
Is rotated, the pair of aperture plates 23 and 24 move, and the aperture is adjusted to an aperture corresponding to the amount of light emission. Normally, since the lamp tube wall temperature is low immediately after the ultraviolet lamp 20 emits light, the aperture 22 is fully opened and the aperture is narrowed as the amount of emitted light increases.

When the platen drum 10 rotates, the leading end of the recording area of the color thermosensitive recording material 11 is
When the number reaches 5, the yellow image is thermally recorded line by line by the thermal head 15. In the thermal recording of the yellow image, each heating element of the thermal head 15 generates heat at a temperature in consideration of the coloring characteristics shown in FIG. The portion where the yellow image is thermally recorded reaches the yellow light fixing device 16, where the light is fixed, and the diazonium salt compound that has not contributed to color development is decomposed and the color forming ability is lost. The light fixing device 16 for yellow has approximately 420
Irradiation with ultraviolet light of nm is performed, and the amount of light is adjusted by the stop 22 so as to be always constant. When the end of the color thermosensitive recording material 11 passes through the yellow light fixing device 16, the yellow ultraviolet lamp 20 stops emitting light.

When the platen drum 10 makes one rotation and the recording area reaches the position of the thermal head 15 again, a magenta image is thermally recorded on the magenta thermosensitive coloring layer 37 line by line. At the same time, the ultraviolet lamp 30 of the magenta light fixing device 17 starts emitting light, and the amount of emitted light is
1 is monitored by a sensor (not shown) provided inside. The light emission amount data from the sensor is sent to the controller 28, and the opening amounts of the aperture plates 32 and 33 are adjusted by a motor (not shown). The yellow motor 2
6, the diaphragm plates 32 and 33 may be moved. The magenta optical fixing device 17 has a wavelength of approximately 365 nm.
Of the magenta thermosensitive coloring layer 37 over the entire surface of the color thermosensitive recording material 11 on which a magenta image is recorded
Is light-fixed. When the end of the color thermosensitive recording material 11 passes through the magenta light fixing device 17, the ultraviolet lamp 3
0 stops light emission.

When the platen drum 10 makes one more rotation,
The color thermosensitive recording material 11 faces the thermal head 15, and the cyan image is thermally recorded line by line by the thermal head 15. This cyan thermosensitive coloring layer 36 has a heat energy required for thermosensitive coloring of approximately 80 mJ / m2.
Since it is not less than m ² , no color develops under normal storage conditions. Further, since the cyan thermosensitive coloring layer 36 is not provided with a light fixing property, the light fixing devices 16 and 17 are turned off.
It is in a state.

After the thermal recording of the yellow image, the magenta image, and the cyan image is completed, the platen drum 10 and the conveying roller pair 14 rotate in reverse. The reverse rotation of the platen drum 10 causes the rear end of the color thermosensitive recording material 11 to
Is guided to the paper supply / discharge passage 13 by the transport roller pair 14.
Nip. Thereafter, the platen drum 10 stops, and the fixing of the color thermosensitive recording material 11 by the clamp member 12 is released.

After the clamp is released, the discharge of the color thermosensitive recording material 11 is started by the rotation of the conveying roller pair 14. As a result, the heat-recorded color thermosensitive recording material 11 is discharged to a tray (not shown) via the paper supply / discharge passage 13.

Next, another embodiment will be described with reference to FIGS. In the above embodiment, the shape of the aperture plate is a flat plate for simplicity of processing, but the aperture plates 40 and 41 of this embodiment are flat.
Has an arc shape according to the shape of the reflector 21. The aperture plates 40 and 41 are provided inside the reflector 21. According to this embodiment, the entire shape of the optical fixing device 42 is made compact, and the same space as in the related art can be used when incorporated into a color thermal printer. The same members as those in the embodiment shown in FIG. 2 are denoted by the same reference numerals.

In the above embodiment, the aperture of the diaphragm is adjusted by monitoring the amount of light emitted from the ultraviolet lamp. However, the amount of light emitted from the ultraviolet lamp increases in accordance with the temperature of the lamp tube wall. The elapsed time may be monitored, and the aperture of the diaphragm may be adjusted according to the elapsed time.

[0024]

As described above, according to the present invention, the amount of light emitted from the optical fixing device is adjusted by the aperture.
Uniform light fixing becomes possible, and it is possible to eliminate uneven fixing in continuous printing and one printing.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a color thermal printer provided with an optical fixing device of the present invention.

FIG. 2 is a perspective view of the optical fixing device of the present invention.

FIG. 3 is a sectional view of the optical fixing device shown in FIG.

FIG. 4 is a graph showing a relationship between an elapsed time of light emission and a light emission amount of an ultraviolet lamp.

FIG. 5 is an explanatory diagram showing a layer structure of a color thermosensitive recording material.

FIG. 6 is a graph showing the color development characteristics of a color thermosensitive recording material.

FIG. 7 is a perspective view showing another embodiment of the optical fixing device.

8 is a cross-sectional view of the optical fixing device shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 platen drum 11 color thermosensitive recording material 15 thermal head 16 light fixing device for yellow 17 light fixing device for magenta 20, 30 ultraviolet lamp 21, 31 reflector 23, 24, 32, 33 aperture plate 27 sensor

Claims (3)

(57) [Claims] 1. A color thermosensitive recording material having a plurality of thermosensitive coloring layers formed on a support, and the thermal recording material and the thermal head are relatively moved while thermal recording is performed on each thermosensitive coloring layer. At the same time, in a color thermal printer that irradiates the heat-recorded portion with ultraviolet rays in a wavelength range peculiar to each heat-sensitive coloring layer to fix the light, a rod-shaped ultraviolet lamp and an opening on the side facing the color thermosensitive recording material An optical fixing device comprising: a reflector having a portion formed therein; and a stop for opening and closing an opening of the reflector, wherein a light amount can be adjusted by opening and closing the stop. 2. The optical fixing device according to claim 1, wherein the light emission amount of said ultraviolet lamp is monitored, and the aperture of said stop is adjusted according to the light emission amount. 3. The optical fixing device according to claim 1, wherein a time elapsed since the start of light emission of the ultraviolet lamp is monitored, and the aperture of the stop is adjusted in accordance with the elapsed time.