JPS6252719B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printer whose print head is movable in the front and rear directions with respect to a print medium and whose print color can be changed, and which is particularly suitable for printing on booklet-like media such as passbooks. Regarding.

In printers using wire dot heads, the gap between the tip of the printing wire and the printing medium is narrow;
Particularly when printing on a booklet such as a bankbook, the ink ribbon shift space for multi-color printing becomes very narrow as one of the open pages becomes thicker, making it difficult to shift the ink ribbon. Therefore, in a printer using a wire dot head like this, when shifting the ink ribbon, the print head is moved back from the printing position to widen the gap between the tip of the print wire and the print medium, and then again after the ink ribbon is shifted. It is conventional practice to return the print head to the printing position.

However, in conventional printers of this type, the print head forward/backward mechanism and the ink ribbon shift mechanism are each driven by independent drive sources, and the operating sequence of both is electrically controlled, resulting in a complex and expensive configuration. It had certain drawbacks. Furthermore, since a magnet was generally used as a driving source for moving the print head forward and backward, a buffering means was required to soften the impact when stopping the print head at a desired position.

The present invention aims to solve the above-mentioned problems, and controls the operation sequence of advancing and retracting the print head and switching the ink ribbon using two cams installed on the same axis, and rotates the shaft using a pulse motor. It is characterized by this.

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

FIG. 1 shows an embodiment of the present invention, and particularly shows a mechanism for moving the printing head forward and backward, and a mechanism for switching the ink ribbon.

In FIG. 1, reference numeral 1 denotes a wire dot type printing head, which is supported on a slide plate 2, which is slidably supported on a carriage (not shown) along two guide shafts 3a and 3b. has been done. 4 and 5 are plates 6
Among the ink ribbon cartridges supported above, one ink ribbon cartridge 4 accommodates a black ink ribbon 7, and the other ink ribbon cartridge 5 accommodates a red ink ribbon 8. These two ink ribbons 7, 8 are pulled out from the ink ribbon cartridges 4, 5, guided in front of the print head 1 by guide means provided on the plate 6, and then drawn into the cartridge again. The plate 6 is the shaft 9a, 9b
It is supported on a carriage (not shown) so as to be rotatable about the center. 10 is the above slide plate 2
The cam lever is connected to the cam lever via a link 11 and is rotatable about a shaft 12, and follows the rotation of the head position control cam 13 to perform fan-shaped movement within a fixed angle. Reference numeral 14 denotes a cam lever provided on the plate 6, which moves the plate 6 in a fan-shaped manner following the rotation of the ribbon switching control cam 15. Both the head position control cam 13 and the ribbon switching control cam 15 are pivotally supported on a square shaft 16, which also pivotally supports a pulley 17. 1
8 is a pulse motor, and a belt 20 is passed between its drive pulley 19 and the pulley 17.
The corner shaft 16 is rotated in a desired direction and by a desired angle. Reference numeral 21 denotes a print medium placed opposite the print head 1.

Next, the operation of the above structure will be explained with reference to FIG.

When the pulse motor 18 is currently stopped and in the state shown in FIG. 1, the print head 1 is in the forward position where it can print, and the black ink ribbon 7 is positioned between the print head 1 and the print medium 21. are doing. The square shaft 16 is driven by the pulse motor 18.
When the head position control cam 13 is rotated, the head position control cam 13 rotates in a direction in which the diameter from the center of the cam shaft to the outer circumference becomes larger, so that the cam lever 10 rotates clockwise about the shaft 12. Therefore, the slide plate 2 is slid upward, and the print head 1 is moved away from the print medium 21. When the head position control cam 13 rotates 90 degrees from the original position, the print head 1 is in the retracted position where the ink ribbons 7 and 8 can be switched, and the gap between the print medium 21 and the print head 1 is wide. . Meanwhile, the ribbon switching control cam 15 is also rotating at the same time, and the cam lever 1
4 and rotate the plate 6 counterclockwise about the shafts 9a and 9b. While the two cams 13 and 15 rotate through the next 90 degrees, the diameter of the ribbon switching control cam 15 from the center of the cam shaft to the outer periphery reaches its maximum, and the plate 6 reaches its final rotational position in the counterclockwise direction. As a result, the ink ribbon cartridges 4 and 5 on the plate 6 and the ribbon guide means are moved so that the red ink ribbon 8 is positioned between the tip of the print head 1 and the print medium 21. On the other hand, head position control cam 13
During this time, the print head 1 rotates in a direction in which the diameter from the center of the camshaft to the outer circumference becomes smaller, so that the print head 1 moves toward the print medium 21 again and is positioned at its original forward position where printing is possible.

Thus, when the square shaft 16 rotates half a turn from its original position due to the rotation of the pulse motor 18, the print head 1 is once retracted from the printing position and then advanced to the printing position again, and the ink ribbon is moved so that the print head 1 is in the retracted position. It switches from black to red for a while.
When switching the ink ribbon from red to black, the corner shaft 16 is similarly turned half a turn.

As explained above based on the embodiments, according to the present invention, the forward and backward operations of the print head and the switching operation of the ink ribbon are performed by one drive source, and both operation sequences are controlled by a cam. This has the effect of making the configuration simple and inexpensive, and since a pulse motor is used as the drive source, it is easy to control the rotation angle of the cam and the speed at which the printing head moves forward and backward. This has the effect of eliminating the need for shaft rotational movement interrupting means such as an electromagnetic clutch or shock absorbing means such as a dart pot.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing the configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation of the embodiment of the present invention. 1... Printing head, 4, 5... Ink ribbon cartridge, 6... Plate, 7, 8... Ink ribbon, 10, 14... Cam lever, 13... Head position control cam, 15... Ribbon switching control Cam, 16... Square shaft, 18... Pulse motor.

Claims (1)

[Claims] 1. In a printer in which a wire-dot type print head is mounted on a carriage so as to be able to move forward and backward toward the print medium, and when changing the color of the ink ribbon, the print head is once retracted from the printing position. a first cam for retracting the print head from the printable position and then advancing it back to the printable position; and a second cam for moving the ink ribbon from one position to the other position while the first cam makes half a rotation. cam, a shaft coaxially supporting the first cam and the second cam, and when printing by switching the color of the ink ribbon, rotate the shaft by half a turn and maintain the rotational position;
A printer comprising: a pulse motor that rotates the shaft further by half a rotation from the rotational position or half a rotation in the opposite direction when switching the ink ribbon to the original color.