JPH0333113B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer recording device, and more particularly to a support mechanism for a thermal head intended to improve the uniformity of recording surface density.

[Prior Art] In recent years, thermal transfer recording devices have been widely used.
In this method, a thermal transfer ribbon and paper are passed between a thermal head and a platen roller, and the heat-melting ink applied to the thermal transfer ribbon is melted by the thermal head and transferred to the paper. In addition to being relatively easy to print in multiple colors, it is also small and
It has features such as being lightweight and producing little noise.

In such a thermal transfer recording device, in order to make the density of the recording surface uniform, it is necessary to make the pressure contact force between the thermal head and the platen roller uniform in the width direction of the recording paper (that is, in the axial direction of the platen roller). At the same time, it is an extremely important condition that the axis of the platen roller and the heating element of the thermal head be perfectly aligned. For this purpose, in the past, while the pressure force in the width direction of the recording paper was uniformly adjusted using an adjustment screw, the alignment of the axis of the platen roller and the heating element of the thermal head depended on the accuracy of the parts. This point will be further explained.

FIG. 4 is a side view showing the structure of a thermal head support mechanism of a conventional thermal transfer recording apparatus. In this figure, a thermal head 3 held by a head holder 2 is pressed into contact with the platen roller 1, and a thermal transfer ribbon 4 and a sheet of paper 5 are passed between them in an overlapping state. It is being conveyed upwards in the figure. Above head holder 2
is attached to a head holder shaft 2a that is rotatably supported on the same frame as the platen roller 1, and is pulled to the right in the figure by a spring 6, whereby the thermal head 3 is pressed against the platen roller 1. has been done. Here, the pressure contact force is adjusted by adjustment screws 7 provided on both sides of the head holder 2, and is made uniform in the width direction of the paper 5. In the figure, 8 is a sensor for detecting the position of the transfer ribbon 4, 9 is a sensor holder that holds the sensor 8, 10 is a fixing screw that fixes the adjustment screw 7,
A heat sink 11 radiates heat from the thermal head 3.

[Problems to be Solved by the Invention] The conventional thermal head support mechanism described above has the following problems.

(1) Adjustment is required to equalize the pressure force between the thermal head and the platen roller.

(2) The structure is complicated because adjustment means such as adjustment screws 7 are provided.

The present invention was made against this background, and it is an object of the present invention to provide a support mechanism for a thermal head that can obtain a uniform pressing force between the thermal head and the platen roller without any adjustment.

[Means for Solving the Problems] In order to solve the above problems, the present invention includes a hinge shaft attached to the frame of the thermal transfer recording device in parallel with the platen roller, and a joint between the platen roller and the hinge shaft. a head holder located between the two and holding a thermal head on a surface facing the platen roller; and a single ball having an inner ring fixed to the center of the hinge shaft and an outer ring fixed to the center of the head holder. The apparatus is characterized in that it includes a bearing and an elastic member that presses both sides of the head holder toward the platen roller.

[Operation] According to the above configuration, the head holder is supported (suspended) on the hinge shaft using the ball bearing as a fulcrum. Therefore, the head holder is rotatable about the hinge shaft and swings about the ball bearing as a fulcrum. This is because a clearance exists between the inner ring and outer ring of the ball bearing.

In this state, when both sides of the head holder are pressed in the direction of the platen roller by the elastic members, the pressing force between the platen roller and the thermal head becomes uniform in the width direction of the recording paper. This is because the central part of the head holder uses a ball bearing as a fulcrum, and both sides of the head holder are pressed by elastic members, so the moments acting on both sides of the head holder automatically become equal, and as a result, the head holder This is because the pressing forces on both sides are also equal.

[Embodiment] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 2, a sheet 23 pulled out from a roll 22 is sent to the outer periphery of the platen roller 21 via a roller 24, and is conveyed to the left side of the figure by folding the outer periphery of the platen roller 21 in a U-shape. Ru. Further, the ink ribbon 25 coated with thermal transfer ink is pulled out from the roll 26, overlapped with the paper 23 on the upper surface of the outer periphery of the platen roller 21, and then wound up by a winder 27.

Next, a support mechanism for the thermal head 50 will be explained. Note that the thermal head 50 itself will be described later.

In FIGS. 1 to 3, 30a and 30b are the left and right frames of the thermal transfer recording device, respectively;
A head holder 31 having a width slightly narrower than the frame width is arranged between the frames 30a and 30b. The head holder 31 is composed of a frame 32 having a substantially U-shaped planar shape, a ball bearing 35, and a supporting member 33.

The frame body 32 is integrally formed with side walls 32a, 32b facing the frames 30a, 30b, and a connecting portion 32c connecting one end of these side walls, and the other end side of the frame body 32 has a substantially rectangular shape in plan view. A shaped support member 33 is fixed. In this way, the central portion of the head holder 31 is open.

The central portion of the support member 33 is gently raised upward as it moves to the right in FIG. 1, and a stepped through hole 34 parallel to the platen roller 21 is formed in this portion. This through hole 34 has a large diameter portion 34a, a medium diameter portion 34b, and a small diameter portion 34c,
The outer ring 3 of the ball bearing 35 is attached to the middle diameter portion 34b.
5a is fixed. Further, spring pressing portions 36a and 36b are formed on the outer sides of both ends of the through hole 34 in a direction perpendicular to the through hole 34. (See Figure 3b). Furthermore, outwardly protruding pins 37a, 37b are fixed to the lower left ends of the side walls 32a, 32b.

The head holder 31 has a hinge shaft 40.
It is attached to frames 30a, 30b by. That is, the hinge shaft 40 is inserted gently into the through hole 34 of the head holder 31, and both ends of the hinge shaft 40 are connected to the screws 41a, 4.
1b to the frames 30a, 30b. In this case, the center portion of the hinge shaft 40 is inserted and fixed into the inner ring 35b of the ball bearing 35, and as a result, the head holder 31
is supported (suspended) on a hinge shaft 40 using a ball bearing 35 as a fulcrum.

A pair of springs 42a and 42b are fitted into both ends of the hinge shaft 40, one end of which is fixed to the frames 30a and 30b, and the other end of which is fixed to the spring pressing portions 36a and 36b.
is in contact with.

Further, the pins 37a and 37b are connected to the frames 31a and 37b.
The head holder 31 is movably fitted into long holes 43a and 43b provided in the head holder 31b, so that the head holder 31 can rotate around the hinge shaft 40.
That is, the long holes 43a and 43b are formed in an arc shape centered on the hinge shaft 40.

A thermal head 50 is fixed to the lower part of the head holder 31. Centering on Figure 2,
This mounting structure will be explained. The thermal head 50 includes a substrate 51 made of ceramics or the like.
A heating element 52 formed at one end of this substrate 51 and extending in the axial direction of the platen roller 21, and a plate-like member 53 that supports the heating element 52 and radiates heat emitted from the heating element 52 to the outside. ,
Stainless steel cover 5 that protects the heating element 52
4 and a connector 55 attached to the center portion of the other end of the substrate 51, and a plate-like member 53 is fixed to the lower surface of the support member 33. Current is then supplied to the heating element 52 via the connector 55.

According to such a configuration, the springs 42a,
The head holder 31 is urged downward by the pressing force of the thermal head 5.
0 is pressed against the platen roller 21. In this case, the pressure force between the thermal head 50 and the platen roller 21 becomes uniform in the axial direction of the platen roller 21. The reason for this will be explained below. As already mentioned, the head holder 31 is supported by the hinge shaft 40 via the ball bearing 35, so it is rotatable around the hinge shaft 40 and swings within a certain range around the ball bearing 35 as a fulcrum. be able to. For this reason, the head holder 31 has a ball bearing 35
The thermal head holder 31 automatically stops when the left and right moments are balanced, and the force with which the head holder 31 presses the thermal head 50 against the platen roller 21 becomes uniform in the axial direction of the platen roller 21.

In addition, pins 37, 37b and elongated holes 43a, 43b
The axis of the platen roller 21 and the heat generating element 52 of the thermal head 50 are aligned by the fit. In this case, pins 37, 37
Since the accuracy of the holes 43a and 43b can be relatively easily increased, the alignment described above can be simplified.

In addition, in the above embodiment, the springs 42a, 4
Although a torsion spring is used for 2b, the present invention is not limited to this, and any elastic body can be used.

[Effects of the Invention] As explained above, in this invention, since the head holder is attached to the ball bearing fixed to the hinge shaft, the pressure contact force between the thermal head and the platen roller can be made uniform in the axial direction of the platen roller. can. As a result, the uniformity of recording surface density can be improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the structure of an embodiment of the present invention, FIG. 2 is a side view showing the structure of the same embodiment, and FIG.
The figures show cross-sections of the head holder; figure a is a cross-sectional view taken along line A-A in Figure 1, figure b is a cross-sectional view taken along line B--
C is a sectional view taken along line C--C in FIG. 1. FIG. 4 is a side view showing the structure of a thermal head support mechanism of a conventional thermal transfer recording apparatus. 21...Platen roller, 30a, 30b...
Frame, 31... Head holder, 35... Ball bearing, 35a... Outer ring, 35b... Inner ring, 40... Hinge shaft, 42a, 42b...
...Spring (elastic member), 50...Thermal head.

Claims (1)

[Claims] 1. In a thermal head support mechanism that aligns the thermal head of a thermal transfer recording device and a platen roller so that they face each other, a hinge shaft is attached to the frame of the thermal transfer recording device in parallel with the platen roller, and a hinge shaft is attached to the frame of the thermal transfer recording device in parallel with the platen roller, a head holder that is located between the thermal head and the hinge shaft and holds the thermal head on a surface facing the platen roller; an inner ring is fixed to the center of the hinge shaft; and an outer ring is fixed to the center of the head holder. 1. A support mechanism for a thermal head, comprising: a single ball bearing; and elastic members that press both sides of the head holder toward the platen roller.