JPS6110994Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a platen adjustment mechanism for moving the platen of a printer back and forth.

1, 2, and 3 are a plan view, a front view, and a side view showing an example of the conventional method, in which the lever 1 is bent in the direction away from the positioning plate 2,
The lever 1 is rotated clockwise or counterclockwise about the shaft 3 while being removed from the notch 2a of the positioning plate 2, and the external force that is bending the lever 1 is removed at the desired position of the notch 2a of the positioning plate 2. If removed, the lever 1 can be positioned in the desired notch 2a. At this time, when the lever 1 is rotated, the shaft 3 is rotated, and the eccentric cams 4 and 5 fitted on the shaft 3 are rotated. Therefore, the platen 6 that is in contact with the cam surfaces of the eccentric cams 4 and 5 is moved back and forth. This allows for a constant adjustment of the gap between the print head and the medium depending on the thickness of the medium, for example.

However, in the above conventional example, the lever 1 is easily bent in the direction of rotation about the shaft 3, so when a strong force is applied to the platen 6, the cam 4,
It bends due to the force that tries to rotate the shaft 3 via the shaft 5. Therefore, even if the lever 1 is positioned as described above, if a strong external force is applied to the platen 6, the platen will move back and forth. In addition, the eccentric cams 4 and 5 have the disadvantage that unless the phases are accurately matched, the distance traveled by the platen 6 due to the rotation of the shaft 3 will be different on the left and right sides. As a result, another adjustment mechanism had to be provided, for example, to make the guide shaft of the print head (not shown) parallel to the platen 6.

In order to eliminate the above-mentioned drawbacks, the present invention rotates the shaft using a wide lever that does not bend in the rotational direction of the shaft but easily bends in the axial direction, and is fitted into the shaft and whose radius increases in proportion to the angle. or decrease)
The platen is moved back and forth in parallel by rotating a spiral cam at a desired angle, and will be described in detail below with reference to the drawings.

4, 5, and 6 are a plan view, a front view, and a side view showing one embodiment of the present invention, and the same elements as in FIGS. 1, 2, and 3 are designated by the same reference numerals. show. In FIGS. 4, 5, and 6, 7 has a leg portion 7a at its lower part, and is a wide lever that does not bend in the direction of rotation of the shaft 3 but easily bends in the axial direction;
8 connects the leg portion 7a of this wide lever 7 to the shaft 3.
Pins 9 and 10 are rotatably fitted into both ends of the shaft 3, and 11 is a spiral cam whose radius increases (or decreases) in proportion to the angle.
0 to the shaft 3. That is, the spiral cam 9 is semi-fixed to the shaft 3.

The operation in the above configuration will be explained. First, the wide lever 7 is positioned in an arbitrary notch 2a of the positioning plate 2. Next, a plate material with a constant thickness is inserted between the print head and the guide shaft (not shown) to form a surface parallel to the guide shaft.
The platen 6 is brought into close contact with this surface. The spiral cams 9 and 10 are then rotated and abut against the platen 6, respectively. At this position, the spiral cams 9 and 10 are fixed to the shaft 3 by tightening the set screw 11. The platen 6 and the guide shaft of the print head (not shown) are now parallel to each other.

If you want to move the platen 6 back and forth depending on the thickness of the medium, first bend the wide lever 7 in a direction that moves it away from the positioning plate 2.
is removed from an arbitrary notch 2a of the positioning plate 2, and rotated around the shaft 3 in this state. When the wide lever 7 rotates, the shaft 3 rotates via the pin 8, so the spiral cams 9 and 10 fixed to the shaft 3 also rotate by the same angle. Since the radius of the spiral cams 9 and 10 increases (or decreases) by the same amount for the same angle from any position, the platen that is in contact with the cam surface of the spiral cams 9 and 10 even if the phases are different. 6 in parallel back and forth. When the platen 6 is moved back and forth to a desired position in this manner, the external force that is bending the wide lever 7 is removed, and the wide lever 7 is positioned in the corresponding notch 2a of the positioning plate 2. The wide lever positioned in this way is attached to the shaft 3.
Since the shaft and spiral cams 9 and 10 do not bend in the direction of rotation, even if the platen 6 is pressed by, for example, a printing needle protruding from a print head (not shown), the shaft and spiral cams 9 and 10 do not rotate, so the platen 6 is also unnecessary. Not before or after.

FIG. 7 is a perspective view showing an embodiment of the wide lever 7, in which a metal plate is punched out into a predetermined shape, and then a part of the upper part is punched out and bent to form a claw 7b.
In addition, since the leg portions 7a can be formed by punching holes 7c in the lower part into which the pins 8 are inserted and then bending them, manufacturing is simple and inexpensive. Further, since the claw 7b can be made sufficiently smaller than the width of the other parts of the wide lever 7, the notch 2a of the positioning plate 2 can also be made small, and therefore the positioning plate 2 can also be made small. Note that 7d is a knob.

Further, FIG. 8 shows the shape of the spiral cams 9 and 10.

As explained in detail above, the present invention rotates the shaft using a wide lever that does not bend in the rotational direction of the shaft but easily bends in the axial direction, and is fitted into the shaft and whose radius increases in proportion to the angle. or decrease)
to move the platen back and forth in parallel by rotating at least one set of spiral cams at a desired angle;
As is clear from the drawings, the outer periphery of this cam is used continuously, and it is easy to adjust the guide shafts of the platen and print head in parallel, and the platen can be moved in parallel as it is. Also, there is an effect that the platen does not move back and forth unnecessarily.

[Brief explanation of the drawing]

1, 2, and 3 are plan views, front views, and side views showing an example of the conventional method, and FIGS. 4, 5, and 6 are plan views showing an embodiment of the present invention. , a front view and a side view, FIG. 7 is a perspective view showing one embodiment of the wide lever 7, and FIG. 8 is a view showing the shape of the spiral cams 9 and 10. 2...Positioning plate, 3...Shaft, 6
...Platen, 7...Wide lever, 8...Pin,
9, 10... spiral cam, 11... screw.

Claims (1)

[Scope of utility model registration request] In a platen adjustment mechanism in which the gap between the platen and the print head and the parallelism of the gap are adjusted by two cams spaced apart from each other on the same shaft disposed along the platen, the cams are adjusted in proportion to the angle. A platen adjustment mechanism characterized by having a shape in which the radius increases or decreases and is attached to a shaft with a set screw or the like.