JPH07125354A - Sheet feeding device of thermal line printer - Google Patents

Abstract

PURPOSE:To enable thermal recording up to the tip part of a sheet feeding direction of recording paper, by a method wherein a pair of pinch rollers are arranged by facing on a pair of capstan rollers arranged on both sides of a platen roller and the recording paper is carried by nipping the recording paper between those. CONSTITUTION:When the first color heat-sensitive recording paper 16 is extruded into a sheet feeding passage 25 by a sheet feeding roller 27, a pair of rollers 5, 6 positioning on both sides of a platen roller 2 begin rotation in the counterclockwise direction simultaneously with that of the sheet feeding roller 27, and pinch rollers 7, 8 in contact with the roller are driven in the counterclockwise direction. Then when the tip part 16a of color heat-sensitive recording paper 16 which ernters a sheet feeding passage 25 is nipped by the pinch rollers 7, 8 and capstan rollers 5, 6, thermal recording by a thermal head 3 is begun. At this starting point of time, since the thermal head 3 is positioned on the center line between both the rollers 5, 6 and 7, 8, a recording begining position of the recording paper 16 becomes the tip and a space becomes considerably small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device for a thermal line printer.

[0002]

2. Description of the Related Art Thermal printers include a thermal transfer recording type in which a thermal head is heated from behind an ink film and the ink of the ink film is transferred onto a recording paper to record an image, and the recording paper is heated by the thermal head. There is a heat-sensitive recording type in which a color is developed to record an image. In these thermal printers, the recording paper sent from the paper feed cassette is conveyed toward the recording position. At this recording position, a thermal head and a platen for receiving the recording paper pressed by this thermal head are arranged.

In a thermal line printer, a recording paper is passed through a thermal head at a predetermined speed by a paper feeding device, and an image is recorded on the recording paper during the passage. As a conventional paper feeding device, a type in which recording paper is wound around the outer circumference of a platen drum with a large diameter and the platen drum is rotated to convey the recording paper, and a capstan roller and a pinch roller are provided near the platen roller with a small diameter. There is a type in which the recording paper is nipped and conveyed between the capstan roller and the pinch roller.

The latter capstan type has an advantage that the thermal line printer can be downsized because a platen roller having a small diameter can be used. However, when the end of the recording paper is nipped by the capstan roller and the pinch roller, the recording start position is the position where the thermal head is facing, and a large margin is left on the recording paper.

In order to deal with this problem, Japanese Unexamined Patent Publication (Kokai) No. 4-2
As described in Japanese Patent No. 41961, a platen roller having a large diameter is used, a capstan roller is arranged so as to come into contact with the platen roller at a position close to the thermal head, and a distance between the capstan roller and the thermal head. A paper feeding device in which the length is shortened is known.

[0006]

However, the capstan roller is of a suitable size because it rotates the platen roller indirectly and nips the recording paper between them to feed the paper. Is used. Therefore, there is naturally a limit to reducing the margin by bringing the capstan roller close to the thermal head.

An object of the present invention is to solve the above problems, and an object thereof is to provide a paper feed mechanism of a thermal line printer capable of performing thermal recording up to the leading end of the recording paper in the paper feeding direction.

[0008]

In order to solve the above-mentioned problems, in the invention according to claim 1, a pair of capstan rollers that rotate together with the platen roller are arranged on both sides of the platen roller, and each capstan roller is A pair of pinch rollers are arranged so as to face each other, and both sides of the recording paper are nipped and conveyed between them. According to the second aspect of the invention, the pressing mechanism for pressing the pinch roller to the capstan roller is provided.

[0009]

Since the pinch roller and the thermal head are aligned on a straight line, the recording start position of the recording paper can be set near the edge of the paper, and the margin is reduced.

[0010]

EXAMPLE As shown in FIGS. 1 to 3, the platen roller 2
Uses a relatively hard rubber roller and is rotatably attached to a chassis (not shown). Directly above the platen roller 2 is arranged a vertical thermal head 3 for performing thermal recording on the color thermosensitive recording paper 16 supported on the platen roller 2. In the thermal head 3, a large number of heat generating elements that form the heat generating element 3 a are arranged in a line in the axial direction of the platen roller 2. Each heating element generates thermal energy according to the density of the pixel to thermally record an image on the color thermosensitive recording paper 16. The platen roller 2 is rotatably supported by the rotating shaft 4.

A capstan roller 5 having a diameter substantially the same as that of the platen roller 2 so as to sandwich the platen roller 2.
6 is fixed to the rotary shaft 4 of the platen roller. The capstan rollers 5 and 6 are metal rollers having fine irregularities on the surface, and control the paper feed amount of the color thermosensitive recording paper 16. When the capstan rollers 5 and 6 rotate, the inter-color thermal recording paper 16 is fed and the platen roller 2
Will follow it.

Pinch rollers 7 and 8 are located so as to face the capstan rollers 5 and 6 on both sides of the thermal head 3. The pinch rollers 7 and 8 are connected to the arms 9a,
It is rotatably attached to 9b in a cantilever manner. The arms 9a and 9b are fixed to a rotating shaft 9d that is rotated by a motor. One arm 9b is biased counterclockwise by a coil spring 9c, and pinch rollers 7 and 8 are pressed against capstan rollers 5 and 6. These pinch rollers 7 and 8 rotate following the capstan rollers 5 and 6. Rubber rollers are usually used as the pinch rollers 7 and 8.

On both sides of the thermal head 3, ultraviolet lamps 10 and 11 which emit ultraviolet rays for optical fixing are respectively arranged. The ultraviolet lamp 10 has an emission peak of about 4
The 20 nm rod-shaped yellow fixing lamp is used, and the ultraviolet lamp 11 is used for magenta fixing light emission peak of about 365 nm. Since the ultraviolet lamps 10 and 11 are formed with a reflective film except for the openings, ultraviolet rays are emitted in a fan shape. Here, in order to reduce the margin of the color thermal paper 16, it is preferable that the ultraviolet lamps 10 and 11 are located as close to the thermal head as possible.

On the left side of the thermal head 3, a paper discharge passage 15 and a retreat passage 20 formed by the guide plates 13 and 14 are provided. Path switching is provided at the confluence of these passages, and when the color thermosensitive recording paper 16 is conveyed, path switching 17 causes
It guides to either the discharge port 15a or the retreat passage 20. The paper discharge roller pair 18 is provided in the paper discharge passage 15 and rotates at the same peripheral speed as the capstan roller 5, and the color thermal recording paper 16
Is sent to the tray 19 through the discharge port 15a.

On the right side of the thermal head 3, there is provided a paper feed passage 25 composed of guide plates 23 and 24. Further, in the cassette chamber connected to the paper feed passage 25, a paper feed cassette 26 in which the color thermosensitive recording papers 16 are stacked and housed is set. A paper feed roller 27 is provided above the paper feed cassette 26, and pushes out the first color thermosensitive recording paper 16 and feeds it into the inlet 25 a of the paper feed passage 25.

A bottom plate 26a is attached to the inside of the paper feed cassette 26, and when the front end side is pushed up by the lift lever 30, the color thermosensitive recording paper 16 at the top is mounted.
The paper feed roller 27.

FIG. 8 shows an example of color thermosensitive recording paper. On the support 30, a cyan thermosensitive coloring layer 31,
A magenta thermosensitive coloring layer 32, a yellow thermosensitive coloring layer 33, and a protective layer 34 are sequentially formed. These thermosensitive coloring layers 31 to 33 are layered from the surface in the order of thermal recording. The cyan thermosensitive coloring layer 31 contains an electron-donating dye precursor and an electron-accepting compound as main components, and develops cyan when heated.

As the magenta thermosensitive coloring layer 33, a diazonium salt compound having a maximum absorption wavelength of about 365 nm,
It contains a coupler which thermally reacts with this to develop a magenta color. The magenta thermosensitive coloring layer 56 loses its coloring ability due to photolysis of the diazonium salt compound when ultraviolet rays in the vicinity of 365 nm are irradiated after the magenta image is thermally recorded by the thermal head 3.

The yellow thermosensitive coloring layer 33 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. The yellow thermosensitive coloring layer 33 is photo-fixed by irradiation with near-ultraviolet rays in the vicinity of 420 nm and loses its coloring ability.

The operation of the thermal printer configured as described above will be described. When the print start switch is turned on, the paper feed roller 27 rotates clockwise. At the same time, a solenoid (not shown) operates to rotate the lift lever 30 counterclockwise. This lift lever 3
In the case of 0, the front end side of the bottom plate 26a is lifted to bring the first color thermosensitive recording paper 16 into contact with the paper feed roller 27.

As shown in FIG. 5, the paper feed roller 27 pushes the first color thermosensitive recording paper 16 toward the paper feed path 25. At this time, the path switching 17 is switched so that the color thermosensitive recording paper 16 is guided to the retreat path 20.

The capstan rollers 5 and 6 start rotating counterclockwise at the same time as the paper feed roller 27. When the capstan rollers 5 and 6 rotate, the pinch rollers 7 and 8 which are in contact with the capstan rollers 5 and 6 follow the clockwise rotation. Color thermal recording paper 1 entering the paper feed path 25 from the paper feed opening 23a
6 is a pinch roller 7, 8 and a capstan roller 5, 6
Is nipped between and.

The tip portion 16 of the color thermosensitive recording paper 16
At the timing when a is nipped between the pressing rollers 7 and 8 and the capstan rollers 5 and 6, the lift lever 30 is lowered and the color thermosensitive recording paper 16 being conveyed is fed to the feeding roller 27.
Get away from.

When the tip portion 16a of the color thermosensitive recording paper 16 is nipped between the pinch rollers 7 and 8 and the capstan rollers 5 and 6, thermal recording by the thermal head 3 is started. At the time when this thermal recording is started, the thermal head is located on the center lines of the capstan rollers 5 and 6 and the nip rollers 7 and 8. Therefore, the recording start position of the color thermal recording paper 16 is near the leading end, and the margin is considerably large. Get smaller.

While the color thermosensitive recording paper is nipped between the pinch rollers 7 and 8 by the rotation of the capstan rollers 5 and 6, the thermosensitive recording paper 16 is conveyed toward the retreat passage 20. During this conveyance, each heating element of the thermal head 3 is heated to a temperature in consideration of the color development characteristics of the yellow thermosensitive coloring layer 31, and the yellow image is thermally recorded on the yellow thermosensitive coloring layer 31 line by line. The ultraviolet lamp 10 is turned on during the thermal recording of the yellow image to fix the recorded yellow thermosensitive coloring layer 33.

As shown in FIG. 6, the color thermosensitive recording paper 16 is used.
When the rear end portion 16b reaches near the position directly below the thermal head 3, the thermal recording of the yellow image ends, and the rotations of the pinch rollers 7 and 8 and the capstan rollers 5 and 6 are temporarily stopped.

Next, the capstan rollers 5 and 6 rotate clockwise, and the pinch rollers 7 and 8 rotate counterclockwise. As a result, the color thermosensitive recording material 16 is returned toward the paper feeding cassette 26, and as shown in FIG.
b enters the paper feed cassette 26. While the color thermosensitive recording paper 16 is returned toward the paper feeding cassette 26, the thermal head 16 thermally records a magenta image line by line on the magenta thermosensitive coloring layer 32. With this,
The UV lamp 11 lights up, and about 3 of these are emitted.
Magenta thermosensitive coloring layer 3 thermally recorded with 65 nm ultraviolet light
2 is fixed.

Again, the capstan rollers 5 and 6 rotate clockwise and the thermal recording of the cyan image is started from the state shown in FIG. In the thermal recording of the cyan image, since the path switching 17 is activated to open the paper discharge passage, the color thermal recording paper 16 enters the paper discharge passage 15 with the leading end 16a at the front. Then, the sheet is nipped by the pair of sheet discharge rollers 18 and discharged onto the tray 19.

In the embodiment shown in FIG. 9, the horizontal thermal head is used instead of the vertical thermal head. In this embodiment, the ultraviolet lamps on the paper feeding side interfere with each other, so that the two ultraviolet lamps 10 and 11 are arranged in the retract passage 50.
It is provided near the entrance of the paper discharge passage 45. The printing procedure is the same as that of the embodiment shown in FIGS. 1 to 7, and the same members are designated by the same reference numerals.

Although the above-mentioned embodiment is a thermal recording type color thermal printer, the present invention can be applied to a thermal transfer recording type color thermal printer using an ink film. This thermal transfer recording type color thermal printer does not require an ultraviolet lamp for fixing, so that it is theoretically possible to eliminate the printing margin. Further, the present invention can be applied to a monochrome thermal printer as well as a color printer.

[0031]

As described above in detail, according to the present invention, the capstan rollers are arranged on both sides of the platen roller, and the pinch rollers are arranged on both sides of the thermal head so as to face each capstan roller. Since the both sides of the recording paper are sandwiched and conveyed, the recording area of the recording paper can be widened and the margin can be extremely reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a paper feeding device of the present invention.

FIG. 2 is a side view of the paper feeding device shown in FIG.

3 is a front view of the paper feeding device shown in FIG. 1. FIG.

FIG. 4 is a schematic view of a printer using the paper feeding device of the present invention.

FIG. 5 is a schematic view similar to FIG. 4 showing a sheet feeding state.

FIG. 6 is a schematic diagram showing a state in which recording of a yellow image is completed.

FIG. 7 is a schematic diagram showing a state in which recording of a cyan image is started.

FIG. 8 is an explanatory diagram showing a layer structure of color thermosensitive recording paper.

FIG. 9 is an explanatory diagram showing another embodiment of the present invention.

[Explanation of symbols]

 2 Platen roller 3 Thermal head 3a Heating element 4 Rotating shaft 5,6 Capstan roller 7,8 Pinch roller 10, 11 UV lamp 15,45 Paper discharge passage 16 Color thermal recording paper 25,50 Evacuation passage 25 Paper feeding passage 26 Supply Paper cassette 27 Paper feed roller

Claims (2)

[Claims] 1. A thermal line printer for recording an image on a recording sheet supported by a platen roller using a thermal head extending in the axial direction of the platen roller, wherein a rotary shaft for rotatably supporting the platen roller is provided, A pair of capstan rollers that rotate together with this rotary shaft is arranged on both sides of the platen roller, and a pair of pinch rollers is arranged facing each capstan roller, and both sides of the recording paper are nipped between them. A paper feeding device characterized in that it is conveyed as a single sheet. 2. The paper feeding device according to claim 1, further comprising a pressing mechanism for pressing the pinch roller against the capstan roller.