JPS61280980A - Apparatus for changing over position of ribbon - Google Patents

Abstract

PURPOSE:To obtain a ribbon position change-over apparatus capable of accurately determining the change-over position of a ribbon, by cooperating a guide shaft with a guide member by a connection link so as to move the guide member to the same direction corresponding to the moving amount of a ribbon base when the ribbon base is revolved to a desired ribbon change-over position by rotating a cam. CONSTITUTION:A guide shaft 8 for guiding a guide member 10, which guides a ribbon to a running direction, in parallel to a platen 3 in a freely slidable manner is mounted and the cams 14 supporting both sides of a ribbon base 5 is connected to gears 11, 12 driven by a motor 113 to be arranged on the same axis and connection links 22 revolving to the same direction as the operation direction of the ribbon base 5 in a state contacted with the rotating cams 14 are provided so as to be connected to both ends of the guide shaft 8 and several engaging parts 15, 16, 17, 18 stepwise determining the revolution positions of said connection links 22 in a state engaged with the connection links 22 are formed to the outer peripheries of the cams 14 and the connection links 22 are energized to one direction. Therefore, the cams and connection links can be effectively stabilized at constant positions regardless of the presence of the backlash between gears driving the cams and a ribbon change-over position is kept extremely accurate.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a ribbon position switching device.

Conventional technology Conventionally, a ribbon cassette for multiple colors is provided in which ribbons that are color-coded into multiple zones are stored in a cassette case, and a ribbon base that holds this ribbon cassette is rotated to an arbitrary position to select the desired color zone. There is one that prints in multiple colors facing the printing position.

Also, a method is often used in which the rotation of a motor is transmitted to a cam via a gear, and the ribbon base is rotated by the cam.

The problem that the invention aims to solve.

Backlash occurs in the gear that transmits the rotation of the motor to the cam, so the position of the ribbon base changes every time the direction of rotation of the motor changes, even if the ribbon base is aimed at the same position. Therefore, some margin must be made for the width of the zone.

This invention was made in view of these points.

The purpose of the present invention is to provide a ribbon position switching device that can accurately determine the ribbon switching position.

Means for Solving the Problems In the present invention, a guide shaft 8 is installed to slidably guide a guide member 10 for guiding the ribbon 4a in the running direction parallel to the platen 3, and both sides of the ribbon base 3 are Supporting cam 1
4 are connected to gears 11 and 12 driven by a motor 13 and arranged on the same axis, and a connecting rod 22 that rotates in the same direction as the operating direction of the ribbon base 5 is connected to the guide shaft 8. A plurality of locking portions 15, 16, 17, and 18 are formed on the outer periphery of the cam 14 to engage with the connecting rod and determine the rotational position of the connecting rod 22 in stages. The rod 22 is biased in one direction.

When the action cam 14 rotates, the ribbon base 5 rotates, the connecting rod 22 also rotates, and the guide shaft 8 rotates together with the guide member 10 in the same direction as the ribbon base 5. The cam 14 is stationary at a predetermined position and the ribbon base 5 and the guide member 10 are stationary at a desired position, but the locking portions 15, 16, 17, 18
and the connecting rod 22 are engaged. In addition, the connecting rod 22 is urged to resiliently engage with the locking portions 15, 16, 17, and 1B. This stabilizes the cam 14 and the connecting rod 22 in a fixed position. Therefore, the positions of the ribbon base 5 and the guide member 10 are maintained accurately regardless of the presence or absence of backlash of the gears 11, 12.

Example An embodiment of this invention will be described based on the drawings.

A platen 3 is rotatably held by opposing frames 1 and 2. A ribbon base 5 that removably holds a ribbon cassette 4 is rotatably held on these frames 1 and 2 about a shaft 6 as a fulcrum. In FIG. 1, a part of the left frame 1 and the left side of the ribbon base 5 are shown cut away, but the frames 1 and 2 rotatably hold the drive shaft 7, and both ends of the guide shaft 8 are moved up and down. A long hole 9 for movably holding is formed. Also, frame 1.
Although not shown in the drawings, a carrier shaft 2 is installed to slidably hold a carrier on which a printing section is mounted along the platen 3. A guide member 10 for guiding the ribbon 4a of the ribbon cassette 4 in a running direction parallel to the platen 3 is slidably held on the guide shaft 8. This guide member 1
0 is also held in the above-mentioned keys so as to be slidable in a direction perpendicular to the ribbon running direction.

A gear 11 is fixed to the left end of the drive shaft 7.
A gear 12 meshed with is directly connected to a motor 13.

Further, cams 14 are fixed to both ends of the drive shaft 7, and concave locking portions 15j 16, 17 are provided on the outer periphery of these cams 14.
．． 18 are formed. Further, shafts 19 are erected on the outside of the frames 1s1 and 2, and a connecting rod 22 formed by connecting two links 20.degree. 21 is rotatably held on these shafts 19. That is, one link 21 is rotatably held by the shaft 19, and has a notch 23 formed at its tip to fit into the guide shaft 8. The other link 20 is formed with an elongated hole 25 that is slidably fitted onto the shaft 19 and through which a screw 24 that is screwed into the link 21 is passed. A pin 2G that engages with any one of .18 is provided upright. The rear end of the connecting rod 22 and both ends of the guide shaft 8 are urged downward by the spring 27.

Furthermore, a drive shaft 29 is provided which is detachably engaged with the ribbon winding shaft 28 of the ribbon cassette 4.

In such a configuration, when the carrier is moved along the platen 3, the guide member 10 is also guided by the guide shaft 8 and moves along the platen 3 to a desired printing position. When the motor 13 is driven and the cam 14 is rotated, the ribbon base 5 rotates about the shaft 6. At this time, the connecting rod 22 rotates about the shaft 19 as a fulcrum.

The guide shaft 8 moves together with the guide member 10 in the same direction in accordance with the amount of movement of the ribbon and the cassette 4. The ribbon base 5 rotates around a shaft 6, but the guide shaft 8 and the guide member 10 move in a vertical plane parallel to the front surface of the print head (see Figs.
(See Figure 7). Therefore, no matter which zone of the ribbon 4a is located at the printing position [A], the distance between that zone and the platen 3 can be set at an appropriate constant distance.

At this time, the cam 14, which is stationary at a predetermined position, has a locking portion 15,
Since the gears 16, 17, and 18 engage the pin 26, no matter which direction the motor 13 rotates, the gears 11, 12
The cam 14 does not move in the rotational direction regardless of the presence or absence of backlash.

Moreover, the force of the spring 27 strengthens the engagement force with the pin 26 and effectively prevents the movement of the cam 14 and the connecting rod 22. Therefore, the ribbon switching position, that is, the position of the ribbon base 5 and the guide member 10 is extremely accurate.

Effects of the Invention Since the present invention is configured as described above, when the cam is rotated to rotate the ribbon base to a desired ribbon switching position, the guide shaft is moved along with the guide member by the connecting rod to correspond to the amount of movement of the ribbon base. Therefore, the guide member can be moved in a plane parallel to the front surface of the print head, and the distance between any zone of the ribbon facing the print position can be adjusted to the proper distance between that zone and the platen. By forming a locking part on the cam and urging the connecting rod, the cam and connecting rod can be set at uniform intervals regardless of the presence or absence of backlash between the gears that drive the cam. It has the advantage that it can be stabilized in a fixed position and the ribbon switching position can be maintained extremely accurately.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a perspective view, and FIG. 2 is a partially enlarged side view of the ribbon base in its lowest position. FIG. 3 is a partially enlarged side view showing the ribbon base in its highest position, and FIGS. 4 to 7rJR are partially side views showing the raising and lowering movement of the ribbon base.

Claims (1)

[Claims] A ribbon base holding a multi-color ribbon cassette is rotatably provided in a direction perpendicular to the longitudinal direction of the platen, and a carrier holding a printing part and moving along the platen or the printing part holds the ribbon cassette. A guide member for guiding the running of the ribbon is connected to be movable in a straight line orthogonal to the running direction of the ribbon, a guide shaft is provided for slidably guiding the guide member parallel to the platen, and the ribbon base A cam that supports both sides of the ribbon base and stops the ribbon base at a desired position is connected to a gear driven by a motor and arranged on the same axis, and comes into contact with the rotating cam and moves in the same direction as the operating direction of the ribbon base. A rotating connecting rod is connected to both ends of the guide shaft, and a plurality of locking portions are formed on the outer periphery of the cam to engage with the connecting rod and stepwise determine the rotational position of the connecting rod. A ribbon position switching device characterized in that the connecting rod is biased in one direction to elastically engage the connecting rod and the locking portion of the cam.