JPH0442142Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a head crimping mechanism for a thermal serial printer, and in particular, a head crimping mechanism for a thermal serial printer that can crimp the head with a simple mechanism. It is related to.

[Prior art]

Conventionally, a head pressure bonding mechanism in a thermal serial printer has been constructed as shown in FIG. 3, for example.

In the figure, a head base 11 is inserted through a guide shaft 12 and a drive shaft 13 that are arranged in parallel. The drive shaft 13 is, for example, a screw shaft formed with a helical groove, and
1 is engaged with the helical groove, the head base 11 is moved in the row direction along both shafts 12 and 13 as the drive shaft 13 rotates. A thermal head holder 14 is held between both side walls of the head base 11, is transported integrally with the head base 11, and is rotatably inserted through the guide shaft 12. A coil spring 15 is stretched between the rear end of the head base 11 (the side far from the platen 16) and the rear end of the thermal head holder 14, and applies rotational force to the thermal head holder 14 in the counterclockwise direction shown in the figure. In the printing area, due to the force of this coil spring 15,
The thermal head portion 14a of the thermal head holder 14 is pressed against the paper 18 wound around the platen 16. Note that 17 is a guide plate provided in a part of the printer frame, and its protruding portion 17a pushes down the rear end of the thermal head holder 14 in the non-printing area of the head base 11, separating the thermal head portion 14a from the platen 16. I'm starting to let them do it.

However, in the above configuration, since the spring pressure that presses the thermal head portion 14a against the platen 16 is applied from a distance, it is difficult to manage the pressing force, and furthermore, the spring force of the coil spring 15 exerts a moment on the guide shaft 12. However, the strength of the shaft must be taken into account to prevent the shaft from bending.

[Purpose of invention]

This invention eliminates the drawbacks of the conventional ones as described above, and provides a head crimping mechanism for thermal serial printers that makes it easy to manage the crimping force of the print head, is easy to assemble, and places less load on the guide shaft. The purpose is to

[Summary of the idea]

This idea places a compression spring between the thermal head holder and the head base so that the pressure force is applied to the part near the printing surface, and the opposite side of the abutting part of the head base that is pressed by the compression spring. The general idea is that the feed guide shaft is not affected by the pressure force by sliding the surface in contact with the chassis.

[Example of idea]

Embodiments of this invention shown in the drawings will be described below.

FIG. 1 shows a printing head mechanism in a thermal serial printer according to this invention, in which numeral 1 is a platen on which thermal paper 9 is placed on a part of its circumference, and a thermal head holder 2 is mounted on this platen 1. A thermal head 3 attached to the top can be crimped. The head holder 2 is rotatably inserted through a guide shaft 4 extending parallel to the platen 1, and is held on both sides of the head base 5 and transported together with the head base 5. The head base 5 is not engaged with the guide shaft 4, and the head base 5 is inserted into the drive shaft 8 in which a helical groove is formed, and a part of the drive shaft 8 is engaged with the helical groove. It is transported along axis 8 by rotation.

Further, a compression spring 6 is disposed between the head base 5 and the thermal head holder 2, and this compression spring 6 presses the vicinity of the contact portion of the thermal head 3 with the platen 1. .

Furthermore, the compression spring 6 of the head base 5
The surface on the opposite side of the contact portion is in contact with a chassis 7 disposed on the machine frame, so that the force of the compression spring 6 does not reach the guide shaft 4 as a rotational moment.

Note that 2a is a lever part of the thermal head holder, and the lever part 2a comes into contact with a protrusion 7a provided at the lower part of the chassis 7 outside the printing area (see FIG. 2), and the thermal head holder 2 is moved to the second position.
Turn the thermal head 3 clockwise in the figure.
is separated from the platen 1 side.

Next, the operation of the above will be explained.

By the operation of the head feeding mechanism, the entire head carriage moves parallel to the platen 1 along the guide shaft 4 and the drive shaft 8, and in the printing area, the thermal head 3 is moved by a compressor arranged between the head base 5 and The spring 6 reliably prints on the thermal paper 9 wrapped around a part of the circumferential surface of the platen 1. In this case, the compression spring 6 prevents the thermal head 3 from coming into contact with the thermal paper 9. Since the thermal head 3 presses the vicinity of the thermal paper 9, the thermal head 3 can obtain a good pressing force against the thermal paper 9, and the compression spring 6 does not apply rotational moment to the guide shaft 4. As a result, the guide shaft 4 can be made thinner, and since the guide shaft 4 is not deformed, there is no fear that the printing position will shift.

In addition, the head base 5 and the lever portion 2a
The contact portion between the chassis 7 and the chassis 7 can be made of a different material, or a roller or the like may be provided to reduce wear between the two.

[Effect of idea]

As mentioned above, this device uses a compression spring to press the vicinity of the print area, making it easier to manage the pressure force of the print head against the platen.Furthermore, the rotational moment due to the spring force is applied to the guide shaft. Since there is no risk of deformation of the guide shaft, there is no need to consider strength, and
This has excellent effects such as the compression spring can be installed from above and assembly is easy.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of this invention,
FIG. 1 is a schematic side view of the print head mechanism, FIG. 2 is an explanatory view showing the relationship between the lower part of the chassis and the thermal head holder, and FIG. 3 is a side view of a conventional example. 1, 16...Platen, 2, 14...Thermal head holder, 2a...Lever portion of the thermal head holder, 3...Thermal head, 4, 12
...Guide shaft, 5, 11...Head base, 6...
... Compression spring, 7 ... Chassis, 8, 13 ... Drive shaft, 9 ... Thermal paper, 14a ... Thermal head section, 15 ... Coil spring, 17 ... Guide plate, 1
7a... protrusion, 18... paper.

Claims (1)

[Scope of Claim for Utility Model Registration] A platen, a guide shaft and a driving screw shaft disposed parallel to the platen, a thermal head, and a thermal head that is rotatably and slidably inserted through the guide shaft and on which the thermal head is mounted. A head holder equipped with a head placement part for placing the head and a lever part for separating the head, and a holder restriction part that is inserted through and engaged with the driving screw shaft and restricts the sliding of the head holder in a part that does not touch the guide shaft. A compression spring is installed between the head base and the head holder to apply rotational force to the head holder in the direction of pressing the thermal head against the platen, and a compression spring is placed in constant contact with the head base so that the head base rotates. A contact sliding part that limits the thermal head to a certain level, and a contact sliding part that presses against the head retraction lever when the thermal head is moved out of the printing area, and moves the thermal head away from the platen against the rotational force of the compression spring. A thermal serial printer comprising: a chassis that has a protrusion that rotates a head holder and supports a platen, a guide shaft, and a driving screw shaft;