JP2987914B2 - Thermal recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording apparatus for printing on thermal recording paper, and more particularly, to a thermal recording apparatus that does not generate a difference in rotation start between both ends of a platen roller. .

[Conventional technology]

As shown in FIG. 2, the driving portion of the conventional thermal recording apparatus includes a thermal head 1, thermal recording paper 2, a platen roller 3, a platen roller gear 4, an idler 5, a stepping motor 9, a stepping motor gear 8, and the like. Is done. 2A is a perspective view of a driving portion of the thermal recording apparatus, and FIG. 2B is a cross-sectional view.

In such a configuration, since a driving force is applied from one side of the platen roller 3 and a pressing force P of about 3 kg or more is applied from the back of the thermal head 1, when the stepping motor 9 rotates, it is twisted on the platen motor shaft. And rotation of the opposite end with respect to the drive shaft is delayed. Of course, it is not a level of twist that can be seen with the naked eye, but with a feed accuracy of 0.125 mm unit (sub-scanning line density 7.7 line / mm) or 0.0625 mm unit (sub-scanning line density 15.4 line / mm),
When white spots occur, they appear clearly.

Further, in the conventional thermal recording apparatus, in order to prevent the twist on the platen roller shaft and to maintain the printing quality, (a) a method of controlling the printing timing by software, and (b) a method of controlling the platen roller shaft and the printing heat generation line. A shifting method or the like is employed.

The method (a) of controlling the print timing by software controls the print timing of the thermal head in anticipation of the activation delay of the drive system with respect to the timing of the print pulse of the stepping motor.
This is effective for sticking and whitening, but it is difficult to cover the difference in rotation delay of the platen roller between the left and right.

Also, (b) the method of shifting the platen roller axis and the printing heat generation line is to incline the axis of the platen roller with respect to the heating element line with respect to the paper feed direction (the platen roller axis on the opposite side to the heating element line). (A method of setting it slightly forward). With this method, it is difficult to set the inclination accurately.

In addition, as a method related to this kind, for example, JP-A-63-283268 and JP-A-57-157771 can be mentioned.

[Problems to be solved by the invention]

In the above prior art, the platen roller is generally driven from one side, but the pressing force of the thermal head causes deformation of the shaft and rubber portion of the platen roller due to torsion during driving. On the side opposite to the drive end, a delay occurs at the start of rotation. For this reason, for example, when a difference occurs in the transport amount for each line due to a mismatch in print timing or sticking due to sticking or the like, and white spots or the like occur due to uneven feeding, one side of the printing surface (non-drive side). Only, there is a problem that the state is conspicuous.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording apparatus which solves such a problem and does not generate a difference in the rotation start between both ends of a platen roller.

[Means for solving the problem]

In order to achieve the above object, the thermal recording device of the present invention is
The platen roller includes a tapered shaft portion whose outer diameter becomes narrower on the drive end side, and a rubber portion wound around the shaft portion and having a thickness inversely proportional to the tapered shape of the shaft portion. .

[Action]

In the present invention, the shaft portion of the platen roller has a tapered shape in which the outer diameter is narrower on the drive end side than the opposite side, and the thickness of the rubber portion wound around the shaft portion is changed in a semi-proportional manner with the thickness of the shaft portion. This prevents a difference in the rotation start between both ends of the platen roller from occurring.

As a result, when printing with the heat-sensitive mechanism, sticking due to sticking, or a feeding failure in which the printing interval varies due to improper printing timing or the like occurs, and as a result,
Even when white spots or the like occur during printing, the influence on the printed image can be reduced and the printing quality can be maintained.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a driving portion of a thermal recording apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 3a denotes a rubber portion of the platen roller 3 made of platen rubber, and 3b denotes a shaft portion of the platen roller 3.

In the present embodiment, the taper of the shaft diameter of the platen roller 3 increases the rubber thickness at the drive end,
As a result, the force that the drive shaft first attempts to rotate is delayed by a large amount of torsion due to the large rubber thickness, so that the delay due to the rotation at the left and right (drive end and non-drive end) is eliminated, and the heat-sensitive recording paper 2 Can be transported.

FIG. 3 is a sectional view of a driving portion of a thermal recording apparatus according to a second embodiment of the present invention.

In FIG. 3, reference numeral 3c denotes a solid rubber portion forming the platen roller 3, and 3d denotes a sponge rubber portion forming the platen roller 3.

In this embodiment, the rubber portion of the platen roller 3 has a two-layer structure of a solid rubber portion 3c on the front side and a sponge rubber portion 3d on the inner side, and the sponge rubber portion 3d having a large deflection due to torsion is thickened on the driving end side. The delay of the start of rotation on the side opposite to the drive side can be made uniform.

FIG. 4 is a perspective view of a driving portion of the thermal recording apparatus according to the reference example of the present invention.

In FIG. 4, 4a is a platen roller gear, 4b is a platen roller gear on the opposite side, 5a is an idler gear, 5b is an idler gear on the opposite side, 6 is an idler gear shaft, 7
Is the central gear.

In this embodiment, the driving force of the stepping motor 9 is transmitted from the central portion (the central gear 7) of the idler gear shaft 6 to the platen roller gears 4a, 4b at both ends of the platen roller rubber via idler gears 5a, 5b at both ends. By doing
The platen roller 3 can start to rotate without twisting at both ends, and the printed image becomes uniform on the left and right. In addition, idler gears 5a and 5b are arranged corresponding to these platen roller gears 4a and 4b.

〔The invention's effect〕

According to the present invention, when printing with the heat-sensitive mechanism, stepping due to gluing, or a feeding failure in which the printing interval varies due to improper printing timing or the like occurs. It is possible to reduce the influence on the printed image due to the difference between the start of rotation of both ends of the roller.

[Brief description of the drawings]

FIG. 1 is a sectional view of a driving part of a thermal recording apparatus according to a first embodiment of the present invention, FIG. 2 is a perspective view and a sectional view of a driving part of a conventional thermal recording apparatus, and FIG. FIG. 4 is a sectional view of a driving portion of the thermal recording apparatus according to the second embodiment, and FIG. 4 is a perspective view of a driving section of the thermal recording apparatus according to the reference example of the present invention. 1: Thermal head, 2: Thermal recording paper, 3: Platen roller, 3a:
Rubber part, 3b: shaft part, 3c: solid rubber part, 3d: sponge rubber part, 4, 4a, 4b: platen roller gear, 5: idler, 5a, 5
b: idler gear, 6: idler gear shaft, 7: central gear,
8: Stepping motor gear, 9: Stepping motor.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 11/00-11/70 B41J 3/20

Claims (1)

(57) [Claims] 1. A thermal head for recording and printing on a thermal recording paper, a platen roller for pressing and transporting the thermal recording paper against the thermal head, and a driving end of the platen roller rotating via an idler. In a thermal recording apparatus provided with a stepping motor for applying force, the platen roller has a tapered shaft portion whose outer diameter becomes narrower on the drive end side, and is wound around the shaft portion to form a tapered shape of the shaft portion. A thermal recording device comprising a rubber portion having an inversely proportional thickness.