JPH0321478A - Printer paper feed mechanism - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the failure of a paper feed pitch in a tractor state by a method wherein a first position at which a roller holder is pressed and a second position at which the roller holder is not pressed are provided on a lever for pressing the roller holder holding a paper feed roller. CONSTITUTION:A change-over between a friction state and a tractor state is conducted by partially rotating a release lever 14 about a rotation center 14b rightward or leftward. The release lever 14 is provided with a projected part 14a, and a cam lever 15 is provided with a cam part 15a. In a tractor state, the projected part 14a is engaged with the cam part 15a, and the cam lever 15 is supported at a position where a lever 8 does not apply a pressing force to a roller holder 7. In a friction state, the release lever 14 is partially rotated rightward, the projected part 14a is disengaged from the cam part 15a, the cam lever 15 is made rotatable about a shaft 9a, and at this time the lever 8 transmits the pressing force of a spring A10 to the roller holder 7.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a paper feeding mechanism for a printer.

[Prior Art J] The paper feeding mechanism of a conventional printer is shown in Figs. 5, 6, and 7. As shown in FIG. 5, when the cut sheet 120 is used due to the frictional force of the platen 102 (hereinafter referred to as the aliction state), the paper feed rollers 105 and 106 are in pressure contact with the platen 2 and rotate as follows; , as shown in FIG. 7, when the fan-hold paper 121 is used in the tractor method (hereinafter referred to as the tractor state), the paper feed roller 105,
106 was released from pressure and was located away from the platen 102. Problem to be Solved by the Invention BJ However, the above-mentioned conventional technology has the following problems. In the friction state shown in FIG.
The rotation of the platen 102 allows the paper to be fed at an accurate pitch. In the tractor state shown in FIG. 7, the tractor pin 103a engages with the paper hole in the fan-hold paper 121, and in order to accurately feed the paper by the tractor pin 103a, the circumferential speed of the platen 102 (arrow 13
0) is faster than the paper feeding speed (arrow l31) of the tractor 103, and is set so that the fan-hold paper 121 slides around the platen 102. At this time, if the fan-hold paper 12l is sufficiently wrapped around the platen 102 and in close contact with the platen 102 as shown in FIG. 7, paper can be fed at an accurate pitch. Paper 121 is on platen 102
If it is not wrapped around the platen 102 and is floating above the platen 102, the periphery of the platen 102 (arrow 130) will touch the tractor 10.
The paper is gradually attracted to the platen 102 by an amount faster than the paper feed speed (arrow 131) of No. 3, and until it comes into close contact with the platen 102, the paper cannot be fed accurately at the bit. As described above, there is a problem in that the paper feeding pitch is defective in the traction condition. Therefore, the present invention is intended to solve such problems, and its purpose is to move the paper feed rollers 105 and 106 to the platen 102 when using the fan-hold paper 121 in a tractive state.
The fan-hold paper 121 is provided with a mechanism for pressing the fan-hold paper 121 from the platen 102 so that it does not float off the platen 102, and by bringing the fan-hold paper 121 into close contact with the platen 102, the paper can be fed at an accurate pitch. However, here, the paper feed roller 105 is in a friction state.
, 106 (arrow 141) is set to a sufficiently strong pressure to prevent the cut paper 120 from slipping around the platen 102, and to prevent the fan hold paper 121 in the tractor state from floating off the platen 102. The pressing force of the paper feed rollers 105 and 106 is such that the paper hole in the fan hold paper 121 feeds the paper while being supported by the tractor bin 103a, so that the paper hole does not go over the tractor bin 103a or tear, and the paper is pushed around the platen 102. It must be set to a weak suppression such that it slides. [Means for Solving the Problems J] The printer paper feeding mechanism of the present invention includes a rotating platen,
A paper feed roller that is in pressure contact with the platen through the printing paper and rotates as a slave, a roller holder that holds the paper feed roller, a lever that presses the roller holder, and a spring A that engages with the lever.
, a spring B that presses against the roller holder, and a paper guide that guides the printing paper to the paper feed roller section, and the lever has a first position where it presses the roller holder and a second position where it does not press the roller holder. It is characterized by having the following. [Function 1] According to the above configuration, the paper feed rollers 5 and 6 are strongly pressed by the spring A10 to the platen 2 in the friction state, and the paper feed rollers 5 and 6 are pressed strongly to the platen 2 by the spring Bll in the tractor state. Press gently. [Example] Fig. 1 and Fig. 2 show the friction state of the present invention.
Figures 3 and 4 respectively show the state of the tractor of the present invention. A rotating platen 2, paper feed rollers 5 and 6 that are in pressure and non-pressure contact with the platen 2 via printing paper, a roller holder 7 that holds the paper feed rollers 5 and 6, and a lever 8 that presses the roller holder 7. , a spring AlO that engages with the lever 8, a lever shaft 9 that rotates the lever 8 in the direction of arrow 32 about the rotation center 9b, a spring Bll that presses against the roller holder 7, and a cam lever 15 that is fixed to the end of the lever shaft 9. , engages with the cam lever 15 and rotates at the arrow 33 at the rotation center 14b.
a release sleeve l4 that can be rotated in this direction, a paper guide 4 that guides the printing paper to paper feed rollers 5 and 6, a print head 1 that moves in the axial direction of the platen 2 in front of the platen 2, and a print head 1 that moves in the axial direction of the platen 2. a paper guide auxiliary plate that is in pressure contact with the platen 2 via the printing paper between the feed rollers 5 and 6;
It consists of a tractor 3 that feeds fan-hold paper 2l at an accurate pitch using a tractor bin 3a behind the platen 2. At this time, the circumferential speed of the platen 2 is set faster than the paper feeding speed of the tractor 3, so that the printing paper is brought into close contact with the platen 2 and the paper is fed at an accurate pitch. Here, we will explain the mechanism for switching between the friction state and the traction state. Switching between the friction state (Figs. 1 and 2) and the tractor state (Figs. 3 and 4) is performed by partially rotating the release lever l4 left and right about the rotation center 14b. 14
is provided with a convex portion l4a, and the cam lever 15 is provided with a cam portion 15a. In the tractor state, as shown in FIG. 4, the convex portion 14a engages with the cam portion 15a, and the lever 8 supports the cam lever 15 at a position where no pressing force is applied to the roller holder 7. In the friction state, the release lever 14 shown in FIG. 4 is partially rotated to the right to release the protrusion 14.
a separates from the cam portion 15a, and the cam lever 15 becomes free to rotate around the rotation center 9a, resulting in the state shown in FIG. At this time, the lever 8 transmits the pressing force of the spring A10 to the roller holder 7. Regarding the friction state of the present invention, the paper feed roller 5,
The pressing force 40 applied to the platen 2 in No. 6 is set so that the used cut sheet 20 is accurately wound around the platen 2 and does not slip around the platen 2. Regarding the tractor state of the present invention, the pressing force 41 of the paper feed rollers 5 and 6 on the platen 2 is such that the fan-hold paper being used is accurately wound around the platen 2, and the paper hole is over the tractor bin 3a or a torn rim. First, it is set to slide around the platen. If the pressing force 4l at this time is too large, the paper hole will go over the tractor bin 3a or break, and if it is too small, the fan-hold paper 2l will float off the platen 2, making it difficult to feed the paper at an accurate pitch. I can't. Also, pressing force 4
l is set smaller than the pressing force 40 in the friction state. [Effects of the Invention] As described above, according to the present invention, the paper is accurately wound around the platen 2 in the tractor state, so that an accurate paper feeding pitch can be obtained.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views showing the friction state of the present invention. Figures 3 and 4 are cross-sectional views showing the state of the tractor of the present invention. Figure 5 is a cross-sectional view showing the friction state of the conventional example. Figures 6 and 7 are cross-sectional views showing the state of a conventional tractor.・Print head, platen, tractor, paper guide, paper feed roller and above Figure 1 33

Claims (1)

[Claims] A rotating platen, paper feed rollers 5 and 6 that are in pressure contact with the platen through printing paper and rotate as a sub-rotation, a roller holder 7 that holds the paper feed roller, a lever 8 that presses the roller holder, and a lever that engages with the lever. It is composed of a spring A10, a spring B11 that presses against the roller holder, and a paper guide 4 that guides the printing paper to the paper feed roller section. and a second position in which the paper feed mechanism does not move.