KR910009065Y1 - Thermal transfer printer - Google Patents

Abstract

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Description

Thermal transfer printer

1 is a schematic side view of a timing pulley of the thermal transfer printer of the present invention.

2 is a plan view showing a part of the timing pulley and the platen.

3 is a vibrometer block diagram for the embodiment of FIG.

4A and 4B are block diagrams showing a progressometer of a conventional thermal transfer printer, respectively.

5 is a noise power level diagram in the embodiment of FIG. 1 and the conventional example in FIG. 4b.

6 is a schematic side view of a second embodiment according to the present invention.

7 is a graph showing the characteristics of the embodiment of FIG.

8 is a schematic side view of a third embodiment according to the present invention.

9 is a schematic side view of a fourth embodiment according to the present invention.

10 is a schematic front view of a fifth embodiment according to the present invention.

11 is an overall side view of a conventional thermal transfer printer.

FIG. 12 is a partial side view of the platen and step motor of FIG.

FIG. 13 is a plan view of FIG.

* Explanation of symbols for the main parts of the drawings

10: step motor 12: timing pulley

14: platen 16: timing pulley

18: timing belt 20: ink ribbon

21: ribbon conveying motor 22: ribbon winding roller

24: ink ribbon winding 26: thermal head

28: recording paper 30: paper cassette

32: feeding roller 33: information board

34: play roller 35: guide roller

36: discharge tray 37: power supply

38 controller 40 axis

42 frame 44 shaft support

50: timing pulley 50a: inner ring

50b: shock absorber 50c: outer ring

54, 54a: notch groove 56, 56a, 58, 60: protruding member

The present invention relates to a thermal transfer printer in which main scanning is performed with a thermal head, and platen is intermittently rotated and subscanned by a timing belt as a step motor, and in particular, platen is intermittent. It relates to a thermal transfer printer to reduce the noise generated as it rotates.

In general, a thermal transfer printer, when a recording sheet is wound on a platen, an ink ribbon is placed on the sheet, and a thermal head is pressed, a line of text is thermally transferred and printed, and then the platen is intermittently rotated. The printer refers to a printer in which the next line of text is printed. An example of the conventional thermal transfer printer described above will be described with reference to FIGS. 11 to 13.

As shown in FIG. 11 and FIG. 13, the thermal transfer printer is provided with a step motor 10, so that the step motor 10 is fitted with a timing pulley 12 and a platen 14 fitted to its output shaft. The platen 14 is intermittently rotated by the timing belt 18 hooked to 16. Here, the timing belt 18 is such that the belt tension is applied to the traveling portion above. On the other hand, the ink ribbon 20 is wound by the ribbon conveying motor 21 and the ribbon winding roller 22 directly under the platen 14 to be wound around the ink ribbon winding 24, and the ink ribbon ( The thermal head 26 on the line 20 is fitted so as to face the platen 14.

Then, the recording paper 28 is sent out from the paper feeding cassette 30 by the paper feed roller 32 and passes between the platen 14 and the ink ribbon 20 via the guide plate 33 and the guide roller 35. Next, about half of the circumference of the platen 14 is wound, and the letters are printed by the thermal head 26, and the recording paper 28 on which the letters are printed is discharged by the delivery roller 34. Will be sent to The thermal transfer printer also includes a power supply 37 for driving the step motor 10 and a controller 38 for controlling the rotation operation of the platen 14 and the like. 40 is supported by the bearing 44 provided in the frame 42 (refer FIG. 13).

In the conventional thermal transfer printer configured as described above, the main injection is made by the thermal head 26, and the sub injection is made by the intermittent rotation of the platen 14, i.e., wound on the platen 14 When the ink ribbon 20 is brought into close contact with the recording paper 28 and thermally transferred to the thermal head 26, the ink ribbon is contacted on the recording paper to print letters. At this time, since the thermal head 28 is pressed by the platen 14 with a force of several kilograms, a very large torque is required to rotate the platen 14 intermittently.

Therefore, a tension for intermittently rotating the platen 14 is applied to the timing belt 18 intermittently, and the platen shaft 40 periodically changes due to the tension and frictional load of the thermal head 36. The force in the axial radius direction acts, and this force is transmitted to the frame 42, causing the frame 42 to vibrate to generate noise. Conventionally, in order to prevent the transmission of vibration and to suppress the occurrence of noise, a cylindrical dustproof rubber is inserted between the frame bearing 44 and the shaft bearing 44 supporting the platen shaft 40, but such a method is employed. The conventional method has caused a problem that the relative position change between the thermal head 26 and the platen 14 is caused to reduce the accuracy of printing.

Therefore, the present invention is designed to solve the above problems, and provides a thermal transfer printer with high printing accuracy while reducing noise, and a thermal transfer printer capable of suppressing noise caused by intermittent rotation of the platen. The purpose is to provide.

The present invention for achieving the above object is a thermal transfer printer for thermally recording information on a recording sheet, the recording sheet is wound around half the circumference, and the information is thermally recorded on the recording sheet A thermostat head for recording the motor, a step motor for intermittently rotating the platen via a timing belt, and a timing motor mounted on the platen to impart the driving force of the step motor to the platen, This timing pulley has an inner ring and an outer ring, while having a timing pulley. A buffer cylinder provided between the outer ring and each of the protrusion means made of a material having a larger elastic modulus than the buffer cylinder on the circumferential surfaces of the inner ring and the outer ring so as to fit into the notch groove formed in the buffer cylinder. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 illustrate a part of a timing pulley and a platen of a thermal transfer printer according to an embodiment of the present invention, and the thermal transfer printer (the FIGS. 11 to 13) The same symbol is used by the same element and description thereof is omitted.

The thermal transfer printer is inserted into a cylindrical inner ring 50a fixed directly by the platen shaft 40 and a cylindrical buffer cylinder 50b made of an elastic material so as to cushion the inner ring 50a. When the timing pulley 50 composed of the outer ring 50c having the edge on the outer circumferential surface rotates intermittently, the radial force acting on the platen shaft 40 is relaxed by the buffer cylinder 50b.

FIG. 3 is a vibration model of the platen axis radial direction of the inventive thermal transfer printer shown in FIG. 1, and FIG. 4a is a vibration model of the platen axis radial direction without using a buffer in the conventional thermal transfer printer. Figure 4b shows a vibration model of the platen shaft radial direction sandwiching the buffer between the bearing and the frame of the conventional thermal transfer printer. In these figures, Ma is the mass of the outer ring 50c of the platen-side timing pulley 50, ma is the mass of the inner ring 50a and the platen 14 of the timing pulley 50, and Ma ₁ is the mass of the timing pulley 50. The mass, ma ₁ is the mass of the platen 14, K, K ₁ is the elastic modulus F of the elastic body is an external force acting on the timing pulley 50 by the intermittent tension of the timing belt 18.

In the conventional thermal transfer printer shown in FIG. 4A, since the elements such as the timing pulley 50 and the platen shaft 40 are fixedly coupled together, the external force F is delivered to the frame 42 as it is. As shown in FIG. 4B, the timing pulley 50 and the platen 14 (Ma ₁ + ma ₁ ) have one degree of freedom in the conventional example in which the buffer cylinder is inserted between the frame 42 and the bearing 44. As shown in FIG. It is known that the transmission rate at which the external force F is transmitted to the frame 42 at this time is less than 1 in the frequency band more than twice the resonance frequency 1 / 2πK / (Ma ₁ + ma ₁ ). Is true. However, since the pullaten 14 is located on the external force (F) side of the vibration model in the vibration model, the displacement becomes larger than when it is fixedly coupled to the frame shown in Fig. 4a, so that the relative displacement with the thermal head 26 is increased. The printing accuracy is reduced.

On the other hand, in the vibration model of the thermal transfer printer of the present invention shown in FIG. 3, the outer force F is the outer ring 50c of the timing pulley whose mass is Ma, and this constitutes a one degree of freedom forced vibration system. Here, in the frequency band more than twice the resonant frequency 1 / 2πK / Ma, the transmission rate is 1 or less, and noise generation caused by the external force F in the radial direction of the platen shaft 40 can be reduced. In addition, even if the timing belt 18 is intermittently changed in tension, the tension is applied only to the outer ring 50c of the timing pulley 50, but there is no relation between the platen 14 and the thermal head 26. Since the displacement does not occur, the problem of lowering the printing accuracy does not occur.

FIG. 5 shows a comparison of the acoustic power level measurement results of the conventional thermal transfer printer shown in FIG. 4a with the thermal transfer printer of the present invention. As can be seen from this graph, the thermal transfer printer of the present invention is weaker than the conventional thermal transfer printer. The power level is as low as 5㏈.

FIG. 6 shows a second embodiment of the thermal transfer printer according to the present invention, which applies the present invention when high precision is required for the way that the recording paper is sent for overprinting such as a color printer. Yes. In this embodiment, a plurality of radial cutout grooves 54 are formed at the same intervals from the outer circumference to the center of the buffer barrel 50b so that the corresponding protrusion is fitted in the cutout groove 54. The protruding means extends from the inner circumferential surface of the outer ring 50c and has a larger elastic modulus than the material of the buffer tube 50b, so that the protruding means has a wing shape 56 made of a material such as plastic. have.

However, in general, the torsional modulus K of cylindrical anti-vibration rubber is expressed by the following equation.

K = 4π. GI / (1r ₁ ² -1 / r ₂ ² ) ‥‥‥‥‥‥ (1)

Where G is the lateral modulus, 1 is the shaft length of the cylinder, and r ₁ and r ₂ are the inner and outer diameters of the cylinder, respectively. When the equation (1) is modified again,

K = 4π. GI r ₁ ² . r ₂ ² / (r ₂ ² -r ₁ ² ) =

4π. GI α ² / (α ² -1) Xr ₁ ² ‥‥‥‥‥‥‥ (2)

It becomes Here, r ₂ / r ₁ = α ² (> 1), and G, I, and r ₁ , r ₂ are constants, and the graph shows the relationship with α ² / (α ² -1) using α as a variable. One is the seventh. From this figure, it can be seen that the elastic modulus K becomes larger as α approaches 1. However, as shown in the embodiment shown in FIG. 6, when the wing-shaped protruding member 56 is formed on the inner circumferential surface of the outer ring 50c, the effective distance for generating the shear twist in the rotational direction of the buffer cylinder 50b is shortened. This has almost the same effect as bringing α closer to one.

On the other hand, the radial elastic modulus of the buffer cylinder (50b) is expressed as the sum of the elastic modulus due to shear torsion and the elastic modulus due to compression and tension. Since it is small, the radial modulus of elasticity of the cylindrical dustproof rubber is almost determined by the modulus of elasticity due to compression and tension. Therefore, in this embodiment, even if the torsional elastic modulus of the shock absorbing cylinder 50b by the wing-shaped protruding member 56 is increased, the elastic modulus in the radial direction does not increase significantly. As a result, the platen 14 and the platen shaft ( In addition to lowering the vibration transfer rate of 40, it is possible to maintain the accuracy of the recording paper conveying direction.

8 shows a third embodiment of the thermal transfer printer according to the present invention. In this embodiment, a notch groove 54a similar to the notch groove 54 described above is formed on the inner circumferential surface of the buffer cylinder 50b. The inner ring 50a of the timing pulley 50 is provided with a protruding member 56a having a shape similar to that of the wing-shaped protruding member 56. In this embodiment, the same effect as the embodiment shown in FIG. 6 can be obtained. Will be.

9 is a fourth embodiment of the thermal transfer printer according to the present invention. In this embodiment, the wing-shaped protrusion member 56a of the timing pulley inner ring 50a and the wing-shaped protrusion member 56 of the timing pulley outer ring 50c are shown in FIG. ) Are formed alternately with each other so that the same effect as described above can be obtained in this embodiment.

FIG. 10 illustrates a fifth embodiment of the thermal transfer printer according to the present invention, in which a protrusion member 60 having a predetermined length is formed along the entire inner circumferential surface of the timing pulley outer ring 50c. Is made of a material having an elastic modulus larger than that of the elastic body constituting the buffer cylinder 50b. In this embodiment as well, the same effect as in the embodiment of FIG. 6 can be obtained.

As described above, the thermal transfer printer according to the present invention rotates the platen intermittently so that the timing pulley 50 equipped with the protruding member can effectively absorb the displacement caused by the change in tension to suppress the generation of noise due to vibration. In addition, the printing accuracy can be improved, and the noise in the office caused by the OA spread can be suppressed.

Claims (3)

A frame 42, a platen 14 supported on the frame 42 to wind the recording paper, a thermal head 26 fixedly mounted to the frame 42 to thermally transfer information to the recording paper, In the thermal transfer printer comprised of the step motor 10 which intermittently rotates the platen 14 via the timing belt 18, the driving force from the step motor 10 is converted into the platen 14. When the timing pulley 50 is installed on the platen 14 and provided to hang the timing belt 18, the timing pulley 50 is provided with an inner ring 50a and an outer ring 50c, and The timing pulley (20) is formed between the inner ring (50a) and the outer ring (50c), and is composed of a buffer cylinder (50b) made of an elastic body, and is fitted into the notch grooves (54, 54a) formed in the buffer cylinder (50b). From the outer circumferential surface of the outer ring 50c or the outer circumferential surface of the inner ring 50a of the 50 in the radial direction of the timing pulley 50 The thermal transfer printer, characterized in that the protruding members (56, 56a, 58, 60) made of a material having a larger elastic modulus than the elastic body constituting the buffer cylinder (50b). The inner and outer circumferential surfaces of the outer ring 50c and the outer circumferential surface of the timing pulley 50 are alternately projected so that the protruding member 58 is inserted into the cutout grooves of the buffer cylinder 50b. Thermal transfer printer characterized in that. According to claim 1, characterized in that the projecting member 60 is projected by a predetermined length along the entire inner circumferential surface of the outer ring (50c) of the timing pulley (50) so as to fit into the cut-out groove of the buffer cylinder (50b). Thermal transfer printer.