JP2861867B2 - Thermal transfer 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 thermal transfer printer, and more particularly, to a thermal transfer printer capable of multicolor printing.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, for example, this type of thermal transfer printer includes a pick roller 66 for feeding a sheet 60 along a sheet path 62 to a printing section 64, and a sheet roller located upstream of the printing section 64. A paper path switching mechanism 68 for switching the path 62 is provided. Further, the thermal transfer printer is provided with a paper detection lever 72 located in the middle of the paper path 62 and capable of inclining in the upstream or downstream direction in contact with the paper 60, and changes the signal by the inclination of the paper detection lever 72. Photo sensor 74 for detecting the presence or absence of paper 60
And Among them, the paper path switching mechanism 68
Is a switching film 69 and the switching film 6
9 is fixed.

[0003] First, at the time of sucking the paper, the paper 60
Is fed by a pick roller 66, passes through a slight gap between the switching film 69 and the paper path 62, and reaches a suction roller 76 of the printing unit 64. And further, the paper 60
The suction roller 76 carries the tip to a position where the tip comes to the platen roller 78. Thereafter, in the case of color printing, the paper 60 is further transported downstream by the platen roller 78 and the paper feed roller 80 to perform partial printing (for example, yellow color).

When the end of the sheet passes through the sheet detecting lever 72, the suction roller 76 and the roller of the printing unit 64 rotate in reverse upon receiving a signal from the photo sensor 74, and the sheet 6
0 is transported upstream. Then, when the end of the sheet reaches the position of the sheet path switching mechanism 68, the sheet 60 passes over the upper surface of the switching film 69 in the opposite direction to the time of feeding.

[0005] Thereafter, the paper 60 is stopped at the printing start position, and printing is performed in the order of magenta and cyan. This behavior is
The path of the paper 60 during the printing of yellow, magenta, and cyan is made the same, and the problem of color shift and pitch unevenness due to the difference in the paper path is eliminated, that is, from the viewpoint of uniform printing quality under the same conditions.

[0006]

However, in the above-mentioned prior art, since the paper path is switched by the film, which is a soft member, the paper is moved and the film is wavy deformed or the mounting position is slightly displaced. For this reason, there has always been a state in which paper jam is likely to occur.

Further, since the switching film 69 is set so as to exhibit the switching function while keeping the same posture, the paper is forced to push up the switching film 69 at the time of feeding.
There is a problem that friction is generated between the leading end portion of the sheet No. 9 and the surface of the paper path to easily cause scratches, and the durability is reduced.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermal transfer printer which can solve the disadvantages of the prior art and reduce the occurrence of paper jams and effectively reduce paper damage.

[0009]

According to the first aspect of the present invention, there is provided a pick roller for feeding a sheet, a printing unit disposed downstream of the pick roller, and a connection between the printing unit and the pick roller. A paper path, a paper path switching mechanism for guiding the paper partially printed by the printing unit in a direction different from the paper path to the pick roller when returning the paper to the upstream side, and protruding into the paper path described above. And a sheet detecting lever provided to be tiltable in the sheet moving direction. Also, a paper path switching mechanism includes a switching plate,
A support shaft rotatably supports one end of the switching plate. The free end (tip) of the above-mentioned switching plate is equipped so that it is always positioned within the paper path by its own weight, and the switching plate is held at a neutral position of the paper detection lever so as not to come into contact with the paper. The switching plate picks up as the paper detection lever tilts due to contact when returning
The paper path leading to the roller is closed by a switching mechanism driving means,
The paper detection lever is equipped.

According to a second aspect of the present invention, in the configuration of the first aspect, the switching mechanism driving means includes a base member fixed to the sheet detecting lever, and an arm member extending from the base member at a substantially right angle to the sheet detecting lever. And a push-up member extending substantially parallel to the sheet detection lever from the arm member.

According to a third aspect of the present invention, the sheet detection lever has a balancer for maintaining the sheet detection lever at a neutral position substantially perpendicular to the sheet path.

[0012]

First, before the paper is fed to the printing unit by the pick roller, the paper detection lever is in the neutral position.
The switching plate of the paper path switching mechanism is held at a position where it does not contact the paper by the switching mechanism driving means.
As a result, the sheet passes through the sheet path without contacting the switching plate, and the leading end thereof contacts the sheet detection lever.
By this contact, the sheet detection lever is tilted to the downstream side, and the sheet passes through the sheet detection lever.

After printing of a part of the information (for example, a specific color) in the printing section, the rollers of the printing section rotate in reverse upon receiving the detection of the passage of the sheet by the sheet detection lever, and the sheet is returned to the upstream side. . When the trailing edge of the sheet comes into contact with the sheet detection lever, the sheet detection lever tilts to the upstream side. Accordingly, the switching plate is released from the holding by the switching mechanism driving means and comes into contact with the paper path by its own weight. by this,
The trailing edge of the sheet is guided along the upper surface of the switching plate in a direction opposite to the time of feeding, and is positioned at a predetermined printing position. Thereafter, the same printing operation is repeated.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 8 denotes a pick roller for sucking the paper 6 from the cassette 4, and reference numeral 10 denotes a printing unit. A paper path 12 is provided between the pick roller 8 and the printing unit 10. A paper path switching mechanism 14 is provided near the pick roller 8 in the paper path 12. A paper detection lever 15 protruding into the paper path 12 is provided near the printing unit 10 of the paper path 12.
Are supported by a shaft 44 so as to be tiltable in the sheet moving direction. Further, the paper detection lever 15 is provided with a switching mechanism driving means 16.

The printing unit 10 includes a suction roller 18 and a pressure roller 20 for feeding the paper 6 to a printing position, a paper feed roller 22 and a pressure roller 24 serving as a main feed roller for feeding the paper 6 at the time of printing. An ink ribbon 26 capable of transferring ink to the paper 6 by applying heat; a thermal head 28 for applying heat to the ink ribbon 26; a platen roller 30 facing the thermal head 28; 32.

The paper path 12 includes a lower guide 34 for substantially guiding the paper 6 and upper guides 36 and 38. The lower guide 34 is formed with a groove 34a having a V-shaped cross section for accommodating the leading end of the switching plate 40 of the paper path switching mechanism 14 in a buried state and preventing the switching at the time of switching. Also, upper guide 3
An opening 37 is formed between 6 and 38 to allow the paper path switching mechanism 14 to move.

The paper path switching mechanism 14 includes a switching plate 40 and a support shaft 42 that rotatably supports one end of the switching plate 40 so that its free end is always in contact with the lower guide 34 under its own weight. ing. Switching board 4
Numeral 0 is formed of a material having shape retaining properties (in other words, a material having a meaningful rigidity with respect to a soft material such as a film material), and as thin as possible without losing such material (rigidity). Things are desirable.

The switching mechanism driving means 16 includes a base member 16a fixed to the sheet detecting lever 15, an arm member 16b extending from the base member 16a at a substantially right angle to the sheet detecting lever 15, and a sheet detecting lever from the arm member 16b. And a push-up member 16c extending substantially in parallel with the push-up member 15. As shown in FIG.
At a neutral position of 5, the push-up member 16c of the switching mechanism driving means 16 is set so as to hold the switching plate 40 at a position where the switching plate 40 does not contact the paper 6. Paper detection lever 15
Is maintained by the balancer 17 attached to the paper detection lever 15.

The presence / absence detection of the paper 6 by the paper detection lever 15 is performed by a transmission type photo sensor 52 whose signal changes when the paper detection lever 15 is tilted. The force required for tilting the sheet detection lever 15 is set to be lower than the conveyance force of the sheet 6.

Next, the printing position setting operation of the paper in the thermal transfer printer will be described with reference to FIGS.

As shown in FIG. 2, before the paper 6 is fed by the pick roller 8, the switching plate 40 of the paper path switching mechanism 14 is lifted by the push-up member 16c of the switching mechanism driving means 16 to a position where it does not contact the paper 6. It is in a state of being left. When the paper 6 is sent out by the pick roller 8 in such a state, the paper 6 is smoothly fed through the paper path 12 without coming into contact with the paper path switching mechanism 14 and contacts the paper detection lever 15.

As a result, the sheet detection lever 15 is tilted to the downstream side by the conveying force of the sheet 6 to allow the sheet 6 to pass. In this case, the switching plate 40 is further pushed up by the displacement of the pushing up member 16c due to the inclination. Also,
The signal of the photo sensor 52 changes due to the tilt of the sheet detection lever 15, and the presence of a sheet is detected. Thereafter, the paper 6 is sent to the platen roller 30 by the suction roller 18 and then sent to the paper feed roller 22 by the platen roller 30, and a part of the printing (yellow) is performed.

Thereafter, the trailing end of the paper 6 is
5, the suction roller 18 and the like of the printing unit 10 rotate in the reverse direction, and the paper 6 is conveyed in the upstream direction. In this case, as shown in FIG. 3, the rear end of the sheet 6 tilts the sheet detection lever 15 to the upstream side and passes. At that time, since the push-up member 16c does not hold the switching plate 40, the switching plate 40 is moved by gravity to the surface (the groove 34a) of the lower guide 34.
Contact

Therefore, the rear end of the sheet 6 is guided to the upper surface of the switching plate 40 in the opposite direction to the time of feeding. In this case, since the switching plate 40 is rigid, the contact of the sheet 6 does not cause waving, and thus guides the sheet 6 without causing a sheet jam. By the switching guide of the switching plate 40, the sheet 6 is not sent again in the direction of the pick roller 8. Further, since the leading end of the switching plate 40 enters the groove 34a and is buried from the surface of the guide body 34, no catch occurs at the switching start point.

When the sheet 6 is sent further upstream and reaches a predetermined printing start position, the feeding of the sheet 6 is stopped. Thereafter, each time one page of each color is printed in the order of magenta and cyan, the paper 6 is once retracted to a predetermined position on the upstream side, and printing of the next color is performed.

Further, in the above embodiment, each component is shown in a specific shape and arrangement. However, the present invention is not limited to this. The shape and arrangement may be appropriately changed as long as the jam can be reduced.

[0028]

As described above, according to the present invention, the switching plate is made of a material having rigidity as compared with the film material, and the paper path switching mechanism does not come into contact with the paper when the paper is sent out. In the related art, it is possible to effectively suppress the occurrence of paper jam due to the wavy deformation caused by the contact at the time of returning the paper, which has occurred in the conventional example, and to avoid the damage to the paper by reducing the friction at the time of feeding. No excellent thermal transfer printer can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a sheet feeding operation of a main part in the embodiment of FIG. 1;

FIG. 3 is an explanatory diagram showing a sheet returning operation of a main part in the embodiment of FIG. 1;

FIG. 4 is a schematic side view showing a conventional example.

[Explanation of symbols]

 6 paper 8 pick roller 10 printing unit 12 paper path 14 paper path switching mechanism 15 paper detection lever 16 switching mechanism driving means 16a base member 16b arm member 16c push-up member 17 balancer 40 switching plate 42 support shaft

Claims (3)

(57) [Claims] A pick roller that feeds out a sheet, a printing section disposed downstream of the pick roller, a paper path connecting the printing section to the pick roller, and a partial printing by the printing section. A paper path switching mechanism that guides the fed sheet in a direction different from the sheet path that reaches the pick roller when returning the sheet to the upstream side; and a sheet that is protruded into the sheet path and is provided to be tiltable in the sheet moving direction. In the thermal transfer printer provided with a detection lever, the paper path switching mechanism is constituted by a switching plate and a support shaft rotatably supporting one end of the switching plate, and a free end of the switching plate is always kept at a free end. It is installed so as to be in contact with the paper path by its own weight, and at the neutral position of the paper detection lever, the switching plate is held at a position where it does not come into contact with the paper, and when the paper is returned. Thermal transfer printer, characterized in that the switching plate is equipped with a switching mechanism driving means for closing the paper path to the pick roller to the sheet detection lever with the tilt of the sheet detection lever by abutment. 2. The control device according to claim 1, further comprising: a base member fixed to the paper detection lever; an arm member extending from the base member at a substantially right angle to the paper detection lever; and an arm member extending from the arm member to the paper detection lever. 2. The thermal transfer printer according to claim 1, wherein said thermal transfer printer comprises a push-up member extending substantially in parallel. 3. The sheet detecting lever according to claim 1, further comprising a balancer for maintaining the sheet detecting lever at a neutral position substantially perpendicular to the sheet path.
Or the thermal transfer printer according to 2.