JPS6336958B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink ribbon feed mechanism that feeds an ink ribbon by moving a carriage.

Conventionally, this type of ink ribbon feed mechanism that feeds an ink ribbon stretched over at least the print area along the direction of movement of a carriage carrying a print head has been designed to combine the movement of the carriage and the feeding of the ink ribbon. It is equipped with a one-way mechanism that allows the ink ribbon to be interlocked or disconnected.When spacing the carriage, the ink ribbon is not sent by disconnecting it, but when the carriage is returned to its original position, it is interlocked and the ink ribbon is sent together with the carriage. It has the advantage that the ink ribbon can be driven by a single motor.

However, in the conventional method, when the carriage is returned, the ink ribbon is sent in conjunction with the carriage, so there is no relative movement between the carriage and the ink ribbon. The same part of the ink ribbon is always located in front of the head, and therefore, from the viewpoint of the life of the ink ribbon, it cannot be used in a printer that prints in both directions.

The present invention eliminates the above-mentioned drawbacks and realizes an ink ribbon feed mechanism for a bidirectional printing printer with a simple mechanism, and will be described in detail below with reference to the drawings.

The drawing is a schematic perspective view showing one embodiment of the present invention. In the figure, 1 is a print head, 2 is a carriage on which this print head 1 is mounted, 3 is a drive wire that drives this carriage 2 in the print line direction, 4 is a guide shaft that guides the carriage 2, 5 is a rack gear, 6 is this rack gear 5
7 is an endless ink ribbon; 8a to 8d are guide rollers that guide the ink ribbon 7; 9 is the pinion gear 6;
a one-way roller that has a one-way mechanism that can rotate only in a clockwise direction, has an outer peripheral surface covered with a high-friction member, and has a diameter twice that of the pinion gear 6;
10 is a printing paper, and 11 is a platen. In addition,
The carriage 2 is provided with a print head 1 and a one-way roller 9 adjacent to each other in the moving direction of the carriage 2, and both sides of the ink ribbon 7 are arranged so as to contact the front part of the print head 1 and the one-way roller 9, respectively. There is.

The operation in the above configuration will be explained. First, the drive wire 3 moves the carriage 2 in the spacing direction and operates the printing head 1 to print the printing paper 1.
Print 0. At this time, as the carriage 2 moves, the pinion gear 6 meshing with the rack gear 5 rolls and rotates clockwise, and the one-way roller 9 rolls due to the ink ribbon 7 and rotates clockwise. At this time, the pinion gear 6 rotates twice as much as the one-way roller 9 depending on the diameter ratio. Therefore, the one-way roller 9 rotates clockwise with respect to the pinion gear 6, and the clutch mechanism is disconnected, so that the ink ribbon 7 merely rolls and is not fed. Therefore, each time the print head 1 moves, a new side of the ink ribbon 7 is positioned in front of the print head 1 and used for printing. When the printing head 1 finishes printing for one line in this way, a feed mechanism (not shown) feeds the printing paper 10 by one line, and then the drive wire 3 moves the carriage 3 in the return direction. While moving, the print head 1 is operated to print on the print paper 10. At this time, as the carriage 2 moves, the pinion gear 6 meshing with the rack gear 5 rolls and rotates counterclockwise, and the one-way roller is rolled by the ink ribbon 7 and rotates counterclockwise. At this time, the pinion gear 6 tries to rotate twice as much as the one-way roller 9 depending on the diameter ratio, but the one-way roller 9 is rotated counterclockwise with respect to the pinion gear 6. The one-way mechanism is activated, and the one-way roller 9 is rotated counterclockwise by the same angle as the pinion gear 6. Therefore, the ink ribbon 7 receives a feeding force from the one-way roller 9 and is fed in a direction opposite to the direction in which the carriage 2 moves. Further, the amount of feeding of the ink ribbon 7 is equal to the amount of movement of the carriage 2. Therefore, while the print head 1 returns by 1/2 line, the same side of the ink ribbon 7 used last time is used for printing, and the print head 1 returns by another 1/2 line to reach the home position. In the meantime, a new side of the ink ribbon 7 is used for printing. Note that the same side of the ink ribbon 7 is used three times in a row as described above, but since it is not used continuously any more, uneven printing density may occur, and the ink ribbon 7 may
will not be damaged.

Note that the present invention is not limited to the above-mentioned embodiments, but for example, the diameter of the one-way roller is made smaller than the diameter of the pinion gear, and when the printing head is spaced, the one-way roller is rotated by the ink ribbon 7 and rotates more than the pinion gear, idling.
Conversely, when the print head returns to its original position, the relative position between the ink ribbon and the print head may be changed by restricting the one-way roller so that it can only rotate by the same angle as the pinion gear due to the action of the one-way roller mechanism. good. At this time, the ink ribbon is moved in the return direction with respect to the printer frame, but since the one-way roller itself is rotating at the same angle as the pinion gear as described above, the ink ribbon does not move toward the print head. The ink ribbon appears to move in the opposite direction to the direction of movement. The one-way roller may rotate only counterclockwise relative to the pinion gear, in which case the ink ribbon is fed when the print head is spaced, and the ink ribbon is fed when the print head returns. Not done. It goes without saying that if the one-way roller and pinion gear have different diameters, the relative position between the print head and the ink ribbon can be changed as the print head moves. In other words, when the diameter of the one-way roller is P, the diameter of the pinion gear is Q, and the amount of movement of the printing head is R, the relative displacement between the printing head and the ink ribbon |S| is expressed by the following formula (1), and the printing The direction of movement of the ink ribbon as seen from the head is opposite to the direction of movement of the print head.

|S|=|R(1-P/Q)| (1) Further, the pinion gear is an example of a rotating body that rotates due to the movement of the carriage, and may be a simple roller, for example, and the rack gear is also rotated by the rotating body. It may be replaced with a force-applying wire, synchronized belt, etc.

As explained in detail above, according to the present invention,
A one-way roller having a different diameter is connected to a rotating body that rotates reciprocatingly with the carriage through a one-way mechanism that rotates only in the feeding direction of the ink ribbon. Since the ink ribbon is fed in contact, the ink ribbon is fed by the difference between the carriage movement and the one-way roller feeding amount in proportion to the ratio of the diameters of this rotating body and the one-way roller. become. Therefore, when the carriage is moved, the same part of the ink ribbon is not always located in front of the print head, which has the advantage that it can be used in a printer that prints in both directions.

[Brief explanation of the drawing]

The drawing is a schematic perspective view showing one embodiment of the present invention. 1...Print head, 2...Carriage, 3...
Drive wire, 4... Guide shaft, 5... Rack gear, 6... Pinion gear, 7... Ink ribbon, 8a to 8d... Guide roller, 9... One-way roller, 10... Print paper, 11... Platen.

Claims (1)

[Claims] 1. A carriage equipped with a print head that prints via an ink ribbon is moved back and forth, and an ink ribbon stretched across at least a printing area along the direction of this back and forth movement is moved back and forth. In the ink ribbon feed mechanism that feeds the ink ribbon through a one-way mechanism, there is a rotating body such as a gear that moves back and forth together with the carriage and rotates with a fixed rack, etc., and a rotating body that rotates only in the feeding direction of the ink ribbon. A one-way roller mounted on a carriage is connected to this rotating body via a one-way mechanism, has a diameter different from that of this rotating body, and feeds the ink ribbon by contacting the outer peripheral surface provided with a high friction member. An ink ribbon feeding mechanism.