JPH04338567A - Paper-feed mechanism of printer - Google Patents

Abstract

PURPOSE:To prevent the generation of the skew feeding of printing paper when a form is fed anew to a platen. CONSTITUTION:The paper-feed mechanism of a printer has a carriage 12, on which a printing head 11 is loaded in front of a platen 1 holding printing paper and which is moved left and right, paper-feed rollers 33 supplying the platen with printing paper 3, a paper-feed driving gear 113 driving a platen gear 21 fixed onto a platen shaft and the paper-feed rollers and a pinion gear 52 supplying the platen and the paper-feed driving gear with power. The printer has a projecting section 12a formed to the carriage and a selecting gear engaged with both or either one of the platen gear or the paper-feed driving gear by press-contacting by the projecting section.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding mechanism for a printer.

0002

2. Description of the Related Art A paper feeding mechanism of a conventional printer is shown in FIGS. 7 and 8.

As shown in FIG. 7, the platen 1 is connected to a motor 51 via a pinion gear 52, an intermediate gear 42, and a platen gear 21. As shown in FIG. The paper feed roller 33 is connected to the motor 51 via a pinion gear 52 , an intermediate gear 42 , a paper feed drive gear 41 , a paper feed gear 31 , a one-way clutch 32 , and a roller shaft 34 . The one-way clutch 32 is fixed to the paper feed gear 31, locks the roller shaft 34 when rotating in the direction of arrow 73, and unlocks the roller shaft 34 when rotating in the direction of arrow 74. Therefore, platen 1
When the paper feed gear 31 rotates in the direction of arrow 72, the paper feed gear 31 rotates in the direction of arrow 73.
The one-way clutch 32 is locked, the roller shaft 34 rotates in the direction of arrow 73, and the paper feeding roller 33 feeds the printing paper 3 in the direction of arrow 70. When the platen 1 rotates in the direction of arrow 71, the paper feed gear 31 rotates in the direction of arrow 74, but the one-way clutch 32 becomes free and the roller shaft 34 does not rotate.

0004

SUMMARY OF THE INVENTION The prior art described above has the following problems.

As shown in FIG. 8, the platen 1 is
When rotating in the direction, the paper feed roller 33 rotates in the direction of the arrow 73 as described above. Then, the leading edge of the printing paper 3 is pushed by the paper feed roller 33 into the contact portion 5 between the platen 1 rotating in the direction of arrow 72 and the feed roller 4 rotating in the direction of arrow 91. At this time, the leading edge of the printing paper 3 is moved to the contact portion 5 by the rotation of the platen 1 and the feed roller 4.
It may be pushed back further or pushed into the contact portion 5 again. Thereafter, the platen 1 starts rotating in the direction of arrow 71 to send the printing paper 3 forward to the printing paper position.

In the conventional paper feeding mechanism, when the printing paper 3 is pushed back from the contact section 5 or pushed into the contact section 5 during the above operations, the leading edge position of the printing paper becomes unstable. Therefore, there was a problem in that skew feeding occurred when paper was fed by the platen 1.

The present invention is intended to solve these problems, and its purpose is to stop the rotation of the platen when the feeding roller feeds the leading edge of the printing paper to the contact area between the platen and the feed roller. By keeping the leading edge of the printing paper stably stationary at the contact point, the next time the paper is fed by the platen, it is possible to prevent the printing paper from being skewed and achieve good paper feeding.

[0008]

[Means for Solving the Problems] The paper feeding mechanism of the present invention has the following features:
A carriage that carries a print head in front of a platen that holds print paper and moves from side to side; a paper feed roller that supplies print paper to the platen; a platen gear fixed on a platen shaft; A paper feeding mechanism of a printer including a paper feeding drive gear to be driven, and a pinion gear for supplying power to the platen gear and the paper feeding drive gear, wherein a protrusion provided on the carriage, the platen gear, and the paper feeding mechanism are provided. The present invention is characterized in that it has a select gear interposed between the drive gear and the pinion gear, and meshes with both or either of the platen gear and the paper feed drive gear by pressing the protrusion.

[0009]

[Operation] According to the above structure of the present invention, by meshing the select gear only with the paper feed drive gear, the platen does not rotate when the paper is fed by the paper feed roller, and the leading edge of the printing paper is the contact point between the platen and the feed roller. It is said that it is stationary at that point. Therefore, skewing of the paper will not occur during the next paper feeding by the platen.

0010

[Embodiment] A first embodiment of the present invention is shown in FIGS. 1 and 2.

Reference numeral 1 denotes a platen that holds printing paper. A paper guide 2 guides the printing paper so as to wrap it around the platen 1. A carriage 12 has a protrusion 12a that pushes the selection gear 61. This carriage 12 mounts the head 11 in front of the platen 1 and moves left and right. 13 and 14 are guide shafts that support the carriage 12. 33 is a paper feed roller, and the paper feed gear 31
The printing paper 3 is fixed coaxially with the printer 3 and sends out the printing paper 3 in the direction of the arrow 70. Reference numeral 43 denotes a paper feeding drive gear, which transfers the power from the pinion gear 52, which is the rotational torque of the motor 51, to the intermediate gear 4.
1 to the paper feed gear 31. Reference numeral 61 denotes a select gear, which is interposed between the platen gear 21, the paper feed drive gear 43, and the pinion gear 52. This select gear 61 is always meshed with the pinion gear 52,
While being pressed by the spring 62, the carriage moves left and right on the shaft 63 by being pressed by the protrusion 12a of the carriage. This horizontal movement causes it to mesh with either or both of the platen gear 21 and the paper feed drive gear 43.

[0012] Here, the paper feeding operation will be explained.

(i) First, the carriage 11 moves to the right and the selection gear 61 is moved to the position shown in FIG.
(in the position where it engages). Next, due to the operation of the motor 51, the paper feed roller 33 rotates in the direction of the arrow 73 via the pinion gear 52, the selection gear 61, the paper feed drive gear 43, the intermediate gear 41, and the paper feed gear 31, and the printing paper 3 is rotated in the direction of the arrow 73. Send in 70 directions. The leading edge of the printing paper 3 is pushed into the contact part 5, the printing paper 3 is deflected, and when it comes to a secure standstill, it stops rotating.

(ii) The carriage 12 moves to the left and holds the selection gear 61 at the position shown in FIG. 4 (a position where it meshes with both the platen gear 21 and the paper feed drive gear 43). Thereafter, the motor 51 rotates, and the platen 1 rotates in the direction of the arrow 71 via the pinion gear 52, the select gear 61, and the platen gear 21, and the paper feed roller 33 rotates in the direction of the arrow 71 via the select gear 61 to the paper feed gear 31. Rotates in 73 directions. As a result, the printing paper 3 is sandwiched between the platen 1 and the feed roller 4, and is wound around the platen 1.
The paper is fed to the front of the printing position.

(iii) When the carriage 11 moves to the left and printing or paper feeding begins, the selection gear 61 is held at the position shown in FIG. 5. In this position, the select gear 61 is meshed with the platen gear 21, so the platen 1 is rotated in the direction of arrow 71 by the rotation of the motor 51 during paper feeding, but the select gear 61 and the paper feed drive gear 43 are not meshed, so Torque transmission from the motor 51 is released from the paper feed roller 33, and the paper feed roller 33 rotates in accordance with the movement of the printing paper 3.

According to this series of operations, the leading edge of the printing paper 3 is reliably pressed against the contact portion 5, and skewing of the paper does not occur when the paper is fed by the platen 1.

A second embodiment of the present invention is shown in FIG.

This embodiment differs from the first embodiment in that the paper feed drive gear 43 and the paper feed roller 33 are interlocked by a timing belt 44. The rest is the same as the first embodiment, and the operation is also the same.

[0019]

According to the present invention, the leading edge of the fed printing paper is accurately pressed against the outer periphery of the platen, and there is an effect that skewing of the paper does not occur when the paper is fed by the platen.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing the paper feeding section same as above.

FIG. 3 is an operation diagram showing the operation of the select gear section same as above.

FIG. 4 is an operation diagram showing the operation of the select gear section same as above.

FIG. 5 is an operation diagram showing the operation of the select gear section same as above.

FIG. 6 is a perspective view showing a second embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional example.

FIG. 8 is a sectional view showing the paper feeding section same as above.

[Explanation of symbols]

1 Platen 2 Paper guide 3 Printing paper 12 Carriage

Claims (1)

[Claims] 1. A carriage that carries a print head in front of a platen that holds print paper and moves from side to side, a paper feed roller that supplies the print paper to the platen, and a platen gear fixed on a platen shaft. A paper feed mechanism of a printer including a paper feed drive gear that drives the paper feed roller, and a pinion gear that supplies power to the platen gear and the paper feed drive gear, wherein a protrusion provided on the carriage; It is characterized by having a select gear interposed between the platen gear, the paper feed drive gear, and the pinion gear, and meshes with both or either of the platen gear and the paper feed drive gear when pressed by the protrusion. The printer's paper feed mechanism.