JPS6280085A - Recorder - Google Patents

Abstract

PURPOSE:To enable a rack and a planetary gear to be securely engaged and disengaged from each other and enable the drag at the time of disengagement to be reduced, by a construction wherein a straight line perpendicular to a meshing tooth surface of a rack for meshing with a planetary gear lines on the rack side of the center of a sun gear and forms a specified angle with the pitch line of the rack. CONSTITUTION:A planetary gear 11 is located on the front side of a sun gear 10 as viewed in a printing direction, the perpendicular X to a meshing tooth surface of a rack 12 for meshing with the planetary gear 11 lies on the rack 12 side of the center 8 of the sun gear 10, with a spacing S therebetween, and the angle theta between the perpendicular X and the pitch line P of the rack is set to be not less than 21 deg.. The planetary gear 11 is provided with an involute tooth profile, while the rack 12 is provided with an asymmetric tooth profile in which the meshing tooth surface is gently sloped while the right side surface is steeply sloped. With this construction, the force of a spring 14 can be reduced, the drag at the time of disengaging the planetary gear 11 can be reduced, and a disengaging driving force W from a driving rod 13 can be reduced.

Description

[Detailed Description of the Invention] Technical Field C] The present invention relates to a recording device that performs printing by mounting an ink ribbon on a carriage, and particularly relates to a recording device that performs printing by mounting an ink ribbon on a carriage, and in particular, connection and disconnection between a rack provided on the main body and a planetary gear provided on the carriage. Transmission of driving force for winding the ink ribbon.

The present invention relates to a recording device that performs stopping.

[Prior art]

Some recording devices, such as printers, facsimiles, and typewriters, have an ink ribbon mounted on a carriage and transfer ink while feeding the ink ribbon between a print head and paper.

As the ink ribbon drive mechanism of this type of recording device, a swingable arm with a sun gear and a planetary gear pivoted is provided on the carriage, and a rack provided on the main body is connected to the planetary gear.
A configuration is adopted in which the ribbon winding driving force is transmitted and stopped by separation.

By the way, in the conventional ribbon drive mechanism, the angle between the perpendicular from the meshing tooth surface of the rack with the planetary gear, that is, the surface pressure direction, and the pitch line of the rack is relatively small (for example, 20 degrees or less). Therefore, the angle between the direction of the frictional force perpendicular to the surface pressure direction and the perpendicular to the rack, that is, the direction in which the planetary gear is removed when the planetary gear is separated, was similarly set to be small.

However, in such a conventional arrangement, the component of the frictional force in the drawing direction of the planetary gear is large, resulting in a large pullout resistance and a problem that the power required to separate the planetary gear is large.

〔the purpose〕

An object of the present invention is to provide a recording device that can solve the problems of the prior art, that can reliably connect and disconnect a rack and a planetary gear, and that can reduce the pulling resistance when disconnecting. Another object of the present invention is to provide a ribbon drive mechanism.

〔overview〕

In the present invention, the planetary gear is located in front of the sun gear in the printing direction, and a perpendicular line from the meshing tooth surface of the rack with the planetary gear passes through the center of the sun gear or the rack side from the center of the sun gear, and The above object is achieved by making the angle between the perpendicular from the tooth surface and the pitch line of the rack 21 degrees or more.

〔Example〕

The present invention will be specifically described below with reference to the drawings.

FIG. 1 shows a plan view of a ribbon drive mechanism of a thermal transfer printer (recording device) according to an embodiment of the present invention, and FIG. 2 is a partial dark blue sectional view taken along line nn in FIG. 1.

In FIGS. 1 and 2, paper 2 is backed up by a paper feed roller 1 that also serves as a platen, and a guide shaft 3 is installed in front of it in parallel with the paper feed roller. It is guided and supported so that it can move in the direction.

An ink ribbon cassette 5 (FIG. 2) is mounted on the carriage 4, so that an ink ribbon for ink transfer can be fed between the print head 6 and the paper 2.

The carriage 4 is provided with a solenoid 7 for pressurizing and separating the print head 6.

On the other hand, the carriage 4 has an arm 9 that can swing around an axis 8.
is provided.

A sun gear 10 is pivotally supported on the arm 9 at the same position as the swing center 8, and a planetary gear 11 that constantly engages with the sun gear is also pivotally supported.

A rack 12 extending parallel to the moving direction A of the carriage 4 is installed in the main body of the recording apparatus.

A driving rod 13 extending to a position near the print head 6 is connected to one end of the arm 9 (the left end in FIG. 1), and the other end of the arm 9 is connected to a drive rod 13 that urges the arm clockwise and drives a planet. A spring 14 that presses the gear 11 against the rack 12 is latched.

The sun gear 10 is coupled to an ink ribbon drive shaft (usually a take-up shaft of an ink ribbon cassette) through a friction clutch, coaxial relationship, or other gear. (Not shown) FIGS. 1 and 2 show a state in which the print head 6 is in pressure contact with the paper 2 and is ready for printing.

In this state, the solenoid 7 is turned on and the print head 6
is pressed against the paper 2 against a return spring (not shown), while the arm 9 is biased clockwise by the spring 14, the planetary gear 11 is pressed against the rack, and the drive rod 13 is connected to the print head. It is far from 6.

Therefore, the carriage 4 is in the printing direction (rightward in Figure 1).
When driven, the sun gear 10 is driven via the planetary gear 11 connected to the rack 12, and the ink ribbon is wound up.

When the solenoid 7 is turned off, the print head 6 moves (rotates) in the direction away from the paper 2 (head amplifier) by a return spring (not shown), and this movement causes the drive rod 1
3, the arm 9 is rotated counterclockwise against the spring 14, the planetary gear 11 is separated from the rack 12, and the ribbon winding driving force is stopped.

FIG. 3 shows a partially enlarged plane of FIG.

In FIG. 3, the planet gear 11 is located in front of the sun gear 10 in the printing direction (right direction), and the rack 12
The perpendicular line X from the meshing tooth surface with the planetary gear 11 is at a distance from the center 8 of the sun gear 10! It passes through the rack 12 side by 1ltS, and is arranged so that the angle θ between the perpendicular X from the meshing tooth surface and the pitch line P of the rack is 21 degrees or more (for example, about 45 degrees).

In the illustrated example, the tooth profile of the planetary gear 11 is an involute tooth profile, and the tooth profile of the rack 12 is an asymmetric tooth profile with a gentle slope on the meshing surface (left side surface) and a steep slope on the right side surface.
This allows the angle between the perpendicular X from the meshing surface and the pitch line P of the rack to be easily set to 21 degrees or more (preferably 45 degrees or more).

Note that the perpendicular line X substantially coincides with the direction of the driving force F since the driving force F acts perpendicularly to the meshing surface during driving force transmission.

Further, the distance WiS between the perpendicular line X and the center of the sun gear 10 is preferably as small as possible in order to reduce the cutting force W transmitted via the drive rod 13.

According to the above configuration, the perpendicular X from the meshing surface of the rack with the planetary gear 11 is closer to the rack 12
Since the arm 9 is arranged so that the moment acting on the arm 9 due to the driving force is always in the clockwise direction, the spring force of the spring 14 can be reduced accordingly.

In addition, since the angle θ between the perpendicular line X and the pitch line P of the rack 12 is set to a large value of 21 degrees or more, the frictional force μF acting in the direction perpendicular to this can be reduced by that amount. The pulling resistance when disconnecting the gear 11 is reduced,
The separation driving force W from the drive rod 13 can be reduced, and separation can be performed smoothly.

Furthermore, if the distance S between the sun gear 10 and the perpendicular line X is reduced to, for example, zero or a minute value, the separation driving force W
can be made even smaller.

In this way, the required driving force of the ink ribbon driving force transmission mechanism can be set to a small value, excess power can be saved, and the apparatus can be downsized.

Note that the present invention can be similarly applied to a driving force transmission mechanism for an ink ribbon other than a cassette type.

〔effect〕

As is clear from the above description, according to the present invention, it is possible to obtain a recording apparatus that can reduce the power required to connect and disconnect the ink ribbon drive force transmission mechanism.

[Brief explanation of drawings]

1 is a plan view showing a ribbon winding drive force transmission mechanism of a recording apparatus according to an embodiment of the present invention, FIG. 2 is a partial vertical sectional view taken along line nu in FIG. 1, and FIG. The figure is a partially enlarged plan view of FIG. 1. 4--Carriage, 5--Ink ribbon cassette, 8--Center of sun gear, 9--Arm,
10...-Sun gear, 11...-Planetary gear, 12
......Rack, X-m--Perpendicular from the meshing surface, P--Rack pitch line, θ--------Angle. Agent Patent Attorney Yasushi Ototo Grain Cylinder 3 Diagram

Claims (1)

[Claims] (1) An ink ribbon is mounted on a carriage, and a swingable arm supporting a sun gear and a planetary gear is provided on the carriage, and the ribbon is wound by connecting and disconnecting the rack provided on the main body and the planetary gear. In a recording device that transmits and stops driving force, the planetary gear is positioned in front of the sun gear in the printing direction, and the perpendicular from the meshing tooth surface of the rack with the planetary gear is the center of the sun gear or the center of the sun gear. A recording device that passes closer to the rack and is characterized in that the angle between the perpendicular from the meshing tooth surface and the pitch line of the rack is 21 degrees or more.