JPH0548195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a so-called serial type thermal printer equipped with a cassette for storing an ink ribbon for thermal transfer.

(Prior Art) The schematic structure of a conventional thermal printer of this type can be shown in FIGS. 1 to 3. In these figures, reference numeral 1 denotes a platen, and a recording paper 3 is pressed against the platen 1 by a paper presser 2. As shown in FIG. Reference numeral 4 denotes a cassette containing an ink ribbon 5 for thermal transfer, and a rectangular notch 6 is provided in the center of the end on the platen 1 side. The ink ribbon 5 is exposed to the outside at this notch. Further, one end of the ink ribbon 5 is fixed to a take-up roller 7, and the other end is fixed to a delivery roller 8. The take-up roller 7 is rotated manually by a knob 19 as necessary, and is also rotated by a drive shaft 9 during the forward stroke of the printing operation (when moving in the right direction in FIGS. 1 and 3). It's getting old. Reference numeral 10 denotes a cassette holder, which is fixed to the carriage 11. The cassette 4 is loaded into the cassette holder 10 with the aid of a positioning pin 12. The carriage 11 is guided by a guide shaft 13 and moves in the lateral direction in FIGS. The stopped belt 16 is passed through the drive pulley 14 to the motor 17.
This is now done by moving around. 1
A thermal head 8 is disposed in a space between the notch 6 of the cassette 4 and the ink ribbon 5, and its lower part is pivotably mounted to the carriage 11. Although not shown, the thermal head 18 is always urged by a spring in the direction away from the ink ribbon 5 (that is, it is urged so as to maintain the position shown in FIG. 2) during the forward stroke of the printing operation. (When moving rightward in Figures 1 and 3), the ink ribbon 5 side is forcibly tilted using a solenoid, etc., and the back side of the ink ribbon 5 (the side on which ink is not applied) is At the same time as the heating element is pressed, the recording paper 3 is pressed against the platen 1 to bring the surface of the ink ribbon 5 into contact with the recording paper 3. Further, 20 is a felt rod, 21 is a felt plate, and these have leaf springs 22 on both sides of the ink ribbon 5.
Contact is made using the elastic force of Therefore, dust and the like attached to the ink ribbon 5 are removed here.

In recording with a thermal printer in such a configuration, the carriage 11 is moved in the lateral direction in FIGS. 1 and 3, and the platen 1 is intermittently driven in the direction of the arrow in FIG. 1 for each horizontal printing. It is done by In addition, during the backward stroke of the printing operation (when moving to the left in Figures 1 and 3), the thermal head 1
8 is away from the ink ribbon 5, and thermal transfer is not performed.

Incidentally, in serial type thermal printers, there is a demand for increased printing speed, and efforts are being made to make the base of the ink ribbon 5 thinner. but,
Because of this thinning, even if the ink ribbon 5 was attempted to be peeled off from the recording paper 3 after thermal transfer, it could not be peeled off successfully, resulting in a problem of deterioration of printing quality. According to the inventor's experiments, it was found that this problem could be solved by increasing the peeling angle θ (see Figure 3).
Since a notch 6 is provided at the side end for insertion of the central thermal head 18, it is difficult to make a large peeling angle θ due to the structure, and if you try to make it large, it will cause a lot of damage to the ink ribbon 5. There is a problem in that the ink ribbon is cut during printing operation due to the thinning of the base.

(Object of the Invention) The present invention has been made in view of the above points, and its purpose is to realize a serial type thermal printer with excellent printing quality.

(Structure of the Invention) The structure of the present invention that achieves this object is that a notch for inserting a thermal head is provided at a corner of a cassette that stores an ink ribbon for thermal transfer, and the thermal head is placed in the space formed by the notch. The thermal head is configured so that it comes into contact with the ink ribbon during a printing operation, and an ink ribbon guide is provided that can adjust the peeling angle when the thermal head comes into contact with the ink ribbon. It's something to do.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a partially cutaway plan view showing the main parts of an embodiment of the present invention, FIG. 5 is a partially cutaway plan view showing another operating state of the embodiment of FIG. 4, and FIG. It is an explanatory view about adjustment of a peeling angle. In these figures, parts corresponding to those in FIGS. 1 to 3 are designated by the same reference numerals, and their explanation will be omitted.

The first point in which this embodiment differs greatly from the thermal printer shown in FIGS. 1 to 3 is that a notch 6 is provided at the corner of the cassette 4 through which the thermal head 18 is inserted. The thermal head 18 is disposed in a space between the ink ribbon 5 and the ink ribbon 5, and during the forward stroke of the printing operation, the thermal head 18 is moved as shown in FIG. 5 and brought into contact with the ink ribbon 5.

If the thermal head insertion notch 6 is provided at the corner of the cassette 4 in this way, the ink ribbon 5 can be inserted at the corner of the cassette 4 where the ink ribbon 5 bends as it is wound around the take-up roller 7. Since it is exposed outside the cassette 4, the peeling angle θ can be easily set to a large value. Therefore, printing quality can be improved. Further, by adopting this configuration, it is possible to easily move the thermal head 18 to the edge of the recording paper 3, and it is also possible to obtain the effect that printing can be performed up to the edge of the recording paper 3.

If the recording paper 3 is of a constant quality (roughness, i.e., surface smoothness is constant) and the printing mode is not changed, there is no need to change the peeling angle θ, but for higher quality printing In addition to simply increasing the peeling angle θ, it is necessary to change the peeling angle θ depending on the surface smoothness and printing speed. Therefore, in this embodiment, means for adjusting the peeling angle θ is provided, and this is the second point that is significantly different from the thermal printer shown in FIGS. 1 to 3.

As shown in FIGS. 5 and 6, in this embodiment, in order to meet this requirement, a long hole 5 is bored in the cassette 4, and an ink ribbon 5 is inserted into the long hole 25.
A sliding pin (ink ribbon guide) 6 is fitted into the ink ribbon guide. Here, the sliding resistance between the elongated hole 25 and the sliding pin 6 is selected to such a value that the sliding pin 26 does not move due to the force applied to the sliding pin 26 when the ink ribbon 5 is wound up. .

If the peeling angle is adjustable in this way, the peeling angle θ can be increased by moving the position of the sliding pin 26 as shown in FIG. The peeling angle θ can be set to be optimal for the surface smoothness and printing speed.

Incidentally, the reference numeral 23 in FIG. 4 is a reflective photo sensor for detecting the end of feeding of the ink ribbon 5.
It is fixed to the carriage 11 side. This end detection sensor does not need to be a reflective type photo sensor as described above, but may be a conventionally widely used transmission type photo sensor or the like.

In the above embodiment, the case where the sliding pin 26 is used as an ink ribbon guide is described, but the sliding pin 26 is used as an ink ribbon guide.
A roller may be used instead of 6, or two rollers (pins may be used) 27, as shown in FIG.
The ink ribbon 5 is sandwiched between the rollers 27 and 28.
The position of 8 may be changed continuously or discontinuously. Also, when using the sliding pin 26, a slit may be provided in the sliding pin 29 as shown in FIG. 7B, and the ink ribbon 5 may be passed through the slit. In addition, a notch 6 for inserting the thermal head of the cassette 4 is provided near the corner, as shown in FIG.
As shown by the two-dot chain line, the area near the angle of the cassette 4 may be formed for the purpose of protecting the ink ribbon 5, etc.

(Effects of the Invention) As explained above, according to the present invention, the peeling angle of the ink ribbon can be increased, and
Since the optimum peeling angle θ can be set for various recording papers (surface smoothness) and various printing speeds, printing quality can be improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the main structure of a conventional example. Fig. 1 is a perspective view, Fig. 2 is a side view (showing the cassette lifted up), and Fig. 3 is a partially cutaway plan view. It is. 4 is a partially cutaway plan view showing essential parts of an embodiment of the present invention, FIG. 5 is a partially cutaway plan view showing another operating state of the embodiment of FIG. 4, and FIG. FIG. 7 is an explanatory diagram of adjustment of the ribbon peeling angle, and is an explanatory diagram of another embodiment of the present invention. 1...platen, 2...paper holder, 3...recording paper, 4...
Cassette, 5... Ink ribbon, 6... Notch, 7... Take-up roller, 8... Delivery roller, 9... Drive shaft, 10...
Cassette holder, 11... Carriage, 12... Positioning pin, 13... Guide shaft, 16... Belt, 18... Thermal head, 25... Oblong hole, 26...
Sliding pin, 27, 28...roller.

Claims (1)

[Claims] 1. A notch for insertion of a thermal head is provided in a corner of a cassette that stores an ink ribbon for thermal transfer, and a thermal head is placed in the space formed by the notch, so that the thermal head comes into contact with the ink ribbon during printing operation. What is claimed is: 1. A serial type thermal printer, further comprising: an ink ribbon guide capable of adjusting a peeling angle when the thermal head contacts the ink ribbon.