JPH0911558A - Thermal transfer printer - Google Patents

Abstract

PURPOSE: To provide a thermal transfer printer of preventing the damage of a sheet by suppressing a sheet jam due to the deformation of a sheet route switching mechanism upon movement of the sheet and reducing the friction at the time of sending the sheet. CONSTITUTION: A sheet route switching mechanism 14 is provided on a sheet route 12 between a pick roller 8 and a printer 10. The mechanism 14 has a switching plate 40 and a support shaft 42 for rotatably supporting the plate 40. A sheet detecting lever 15 protruding into the route 12 is provided tiltably in the sheet moving direction on the way of the route 12, and a switching mechanism driving means 16 for holding the plate 40 at the position in no contact with the sheet 6 at the time of sending the sheet is provided at the lever 15.

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 compatible with multicolor printing.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, for example, a thermal transfer printer of this type has a pick roller 66 for feeding a sheet 60 along a sheet path 62 to a printing section 64 and a sheet positioned upstream of the printing section 64. A paper path switching mechanism 68 for switching the path 62 is provided. Further, this thermal transfer printer is located in the middle of the paper path 62 and is capable of tilting in the upstream or downstream direction by contact with the paper 60, and the signal is changed by the tilt of the paper detection lever 72. Photo sensor 74 for detecting the presence or absence of paper 60
And Of these, the paper path switching mechanism 68
Is a switching film 69 and this switching film 6
And a stay 70 for fixing 9.

First, when the sheet is inhaled, the sheet 60
Is sent by the pick roller 66, passes through a slight gap between the switching film 69 and the paper path 62, and then reaches the suction roller 76 of the printing unit 64. Further, the paper 60 is
The suction roller 76 conveys the tip to a position where it comes to the platen roller 78. After that, in the case of color printing, the platen roller 78 and the paper feed roller 80 further convey the paper 60 to the downstream side to perform partial printing (for example, yellow color).

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

Thereafter, the paper 60 is stopped at the print start position and printing is performed in the order of magenta and cyan. This behavior is
This is done from the viewpoint of making the paths of the paper 60 the same when printing yellow, magenta, and cyan so as to eliminate the problems of color misregistration and pitch unevenness due to differences in the paper paths, that is, uniform print quality under the same conditions.

[0006]

However, in the above-mentioned prior art, since the sheet path is switched by the film which is the soft member, the wavy deformation of the film and the slight deviation of the mounting position occur as the sheet moves. Therefore, there has always been a state in which a paper jam is likely to occur.

Further, since the switching film 69 is set so as to exhibit the switching function in the same posture, the paper is forced to push up the switching film 69 at the time of feeding, which causes the switching film 6 to move.
There is a problem that friction is likely to occur between the front end portion of 9 and the surface of the paper path to cause scratches, and durability is deteriorated.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermal transfer printer capable of improving the disadvantages of the prior art, particularly reducing the occurrence of paper jam and effectively reducing the damage of paper.

[0009]

According to a first aspect of the present invention, a pick roller for feeding a sheet, a printing section disposed on the downstream side of the pick roller, and the printing section and the pick roller are connected to each other. A paper path, a paper path switching mechanism that guides a partially printed paper in the printing unit in a direction different from the paper path to the pick roller when returning to the upstream side, and is projected into the above-mentioned paper path. In addition, a paper detection lever provided so as to be tiltable in the paper movement direction is provided. In addition, the paper path switching mechanism, the switching plate,
It is composed of a support shaft that rotatably supports one end of the switching plate. The free end (tip end) of the switching plate is installed so that it is always positioned in the paper path by its own weight, and the neutral position of the paper detection lever holds the switching plate in a position where it does not contact the paper. The sheet detection lever is equipped with a switching mechanism driving unit that opens the switching plate when the sheet detection lever is tilted due to the contact at the time of returning.

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

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

[0012]

Operation: First, the paper detection lever is at the neutral position before the paper is sent to the printing section side by the pick roller.
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 paper passes through the paper path without contacting the switching plate, and the leading end of the paper contacts the paper detection lever.
Due to this contact, the paper detection lever tilts to the downstream side, and the paper passes through the paper detection lever.

After a part of the information (for example, a specific color) is printed in the printing section, the roller of the printing section is rotated in the reverse direction upon 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 contacts the sheet detection lever, the sheet detection lever tilts toward the upstream side. Along with this, the switching plate is released from the switching mechanism driving means and comes into contact with the sheet path by its own weight. As a result, the trailing edge of the paper is guided along the upper surface of the switching plate as opposed to the time of feeding, and is positioned at a predetermined printing position. After that, 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 indicates a pick roller for sucking the paper 6 from the cassette 4, and reference numeral 10 indicates a printing portion. 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 of the paper path 12. Further, a paper detection lever 15 protruding into the paper path 12 is provided near the printing section 10 of the paper path 12.
However, it is supported by a shaft 44 so as to be tiltable in the paper movement direction. Further, the paper detection lever 15 is equipped with a switching mechanism drive means 16.

The printing unit 10 includes a suction roller 18 and a pressure roller 20 that feed the paper 6 to a printing position, a paper feed roller 22 and a pressure roller 24 that are main feed rollers that feed the paper 6 at the time of printing, and ink is applied thereto. 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, and an ink ribbon roller. 32 and 32.

The paper path 12 is composed of a lower guide 34 that substantially guides the paper 6 and upper guides 36 and 38. Among these, the lower guide 34 is formed with a groove 34a having a V-shaped cross section for accommodating the tip of the switching plate 40 of the paper path switching mechanism 14 in a buried state to prevent catching at the time of switching. Also, the upper guide 3
An opening 37 is formed between 6 and 38 to allow movement of the paper path switching mechanism 14.

The paper path switching mechanism 14 is composed of a switching plate 40 and a support shaft 42 which rotatably supports one end of the switching plate 40 so that the free end side always contacts the lower guide 34 under its own weight. ing. Switching plate 4
0 is formed of a material having shape retention (in other words, a material having rigidity in the sense of a soft material such as a film material), and is as thin as possible without losing the material (rigidity). Things are desirable.

The switching mechanism driving means 16 includes a base member 16a fixed to the paper detection lever 15, an arm member 16b extending from the base member 16a substantially at right angles to the paper detection lever 15, and a paper detection lever from the arm member 16b. It is composed of a push-up member 16c extending substantially parallel to 15. As shown in FIG. 1, the paper detection lever 1
In the neutral position of 5, the push-up member 16c of the switching mechanism driving means 16 is set to hold the switching plate 40 at a position where it does not contact the paper 6. Paper detection lever 15
The neutral position is maintained by the balancer 17 attached to the paper detection lever 15.

The presence / absence of the sheet 6 is detected by the sheet detection lever 15 by a transmission type photosensor 52 whose signal changes when the sheet detection lever 15 is tilted. The force required to tilt the paper detection lever 15 is set to be less than the carrying force of the paper 6.

Next, the print 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 sent out 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 When the paper 6 is sent out by the pick roller 8 in such a state, the paper 6 is smoothly sent through the paper path 12 without contacting the paper path switching mechanism 14 and comes into contact with 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 and allows the sheet 6 to pass therethrough. In this case, the switching plate 40 is further pushed up by the displacement of the pushing-up member 16c due to tilting. Also,
The signal of the photo sensor 52 changes due to the tilt of the paper detection lever 15, and the presence of paper is detected. After that, 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 to perform a part of printing (yellow).

Thereafter, the trailing edge of the sheet 6 is the sheet detection lever 1
After passing 5, the suction roller 18 and the like of the printing unit 10 rotate in the reverse direction, and the paper 6 is sent in the upstream direction. In this case, as shown in FIG. 3, the trailing edge of the sheet 6 tilts the sheet detection lever 15 to the upstream side and passes through. At that time, since the push-up member 16c does not hold the switching plate 40, the switching plate 40 is gravitationally moved to the surface of the lower guide 34 (the groove 34a).
Contact

Therefore, the trailing edge of the sheet 6 is guided to the upper surface of the switching plate 40, contrary to the time of feeding. In this case, since the switching plate 40 has rigidity, the contact of the sheet 6 does not cause waviness, and thus guides the sheet 6 without causing a sheet jam. The switching guide of the switching plate 40 prevents the paper 6 from being fed again in the direction of the pick roller 8. Further, since the tip of the switching plate 40 enters the groove 34a and is buried in the surface of the guide body 34, the switching plate 40 does not get caught at the switching start point.

When the paper 6 is sent further upstream and reaches a predetermined print start position, the feed of the paper 6 is stopped. After that, 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 the next color is printed.

Further, in the above embodiment, the respective constituent elements are shown in a specific shape / arrangement form, but the present invention is not limited to this, and it is possible to suppress the deterioration of the durability due to the friction at the time of inhaling the sheet and the sheet at the time of returning. The shape / arrangement form may be appropriately changed within a range in which 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 contact the paper at the time of feeding the paper. In the conventional example, it is possible to effectively prevent the occurrence of a paper jam due to the wavy deformation due to the contact at the time of returning the paper, and to reduce the friction at the time of feeding to prevent the paper from being damaged. It is possible to provide a superior thermal transfer printer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an 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.

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

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

[Explanation of symbols]

 6 paper 8 pick roller 10 printing section 12 paper path 14 paper path switching mechanism 15 paper detection lever 16 switching mechanism drive means 16a base member 16b arm member 16c pushing member 17 balancer 40 switching plate 42 support shaft

Claims (3)

[Claims] 1. A pick roller for feeding a sheet, a printing section disposed on the downstream side of the pick roller, a sheet path connecting the printing section and the pick roller, and a partial printing by the printing section. A paper path switching mechanism that guides the formed paper in a direction different from the paper path to the pick roller when returning the paper to the upstream side, and a paper that is projectable into the paper path and tiltable in the paper movement direction In a thermal transfer printer provided with a detection lever, the paper path switching mechanism is composed of a switching plate and a support shaft that rotatably supports one end of the switching plate, and the free end of the switching plate is always Installed so as to contact the paper path by its own weight, hold the switching plate in a position where it does not contact the paper at the neutral position of the paper detection lever, and return the paper. Thermal transfer printer characterized by being equipped with switching mechanism driving means for opening the switching plate along with the tilting of the sheet detection lever by abutting on the sheet detection lever. 2. The switching mechanism driving means includes a base member fixed to the paper detection lever, an arm member extending from the base member at substantially right angles to the paper detection lever, and the arm member connected to the paper detection lever. The thermal transfer printer according to claim 1, wherein the thermal transfer printer comprises a pushing member extending substantially in parallel. 3. The paper detection lever comprises a balancer for maintaining the paper detection lever in a neutral position substantially perpendicular to the paper path.
Or the thermal transfer printer according to 2.