JPS6374859A - Paper feed device for printer - Google Patents

Abstract

PURPOSE:To provide a simple structure having a satisfactory assemblability, by forming a relieving cut-out in a slot formed in a paper guide, in a part corresponding to a tractor pin so that the number of required component parts may be reduced without deteriorating the function of the paper feed device. CONSTITUTION:A tractor pin 14 corresponding to the position of a paper guide 30, projects at its forward end from a slot 38 formed in the paper guide 30, and therefore, the paper guide 30 integrally incorporated with a tractor frame 32 hinders the installation of a sprocket 10 onto the tractor frame 32. Accordingly, a relieving cut-off 48 is formed in the slot 38 corresponding to the tractor pin 14, and therefore, the interference between the tractor pin 14 and the paper guide 30 is eliminated in the intermediate stage of the installation in which a punch 44 allows the tractor pin 14 to project. Accordingly, the component parts are unified, thereby it is possible to reduce ths number of required component parts and to provide a simple structure having a satisfactory assemblability.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a paper feeding device for a printer.

(Prior Art) As shown in FIG. 5, a conventional printer paper feeding device includes a sprocket 52 held between a pair of tractor frames 50a and 50b, and tractor pins 54 arranged radially within the sprocket 52. Bolt 5 for connecting the lock lever 56 and the L-actor frame 50a150b
8. Nut 60, washer 62 and paper guide 53
It is composed of many parts such as.

Then, the tractor bin 54 is fitted into a paper feeding hole provided on the side surface of the fanfold paper (not shown), and the fanfold paper is fed in a predetermined direction by the rotation of the sprocket 52 as the platen shaft 64 rotates. I have to.

At that time, when the sprocket 52 rotates, the tractor pin 54
is engaged in advance with a cam portion 51 provided on the end surface of the tractor frame 50a, so that the tractor pin 54 is prevented from protruding into and out of the outer periphery of the sprocket 52 along the cam portion 51. That is, the tractor pin 54 protrudes to the outer periphery of the sprocket 52 in correspondence with the cam portion 51.

The tractor pin 54 moves in and out at predetermined positions to avoid interference with a print head (not shown). That is, the tractor pin 54 is connected to the sprocket 5 near the paper guide 53.
2, and does not protrude near the level of the print head.

(Problems to be Solved by the Invention) However, the paper feeding device described above has the following problems.

Since there is a pair of tractor frames, the position of the tractor pin in the sprocket is determined using a sophisticated jig, the sprocket is rotatably attached to the side of the tractor frame that has the cam part, and then the other tractor frame is attached. At the same time, the sprocket and throat are clamped together, and the tractor frame is connected using the pole dona and throat.

Therefore, the outer edges of the pair of tractor frames must be aligned, which is troublesome.

Furthermore, the tractor frame has a large number of parts, which causes high costs and reduced work efficiency.

Therefore, it is an object of the present invention to provide a paper feeding device that integrates parts, has a small number of parts, is easy to assemble, and has a simple structure without impairing functionality.

(Means for solving problems) In order to solve the above problems, the present invention has the following configuration.

That is, it has a shaft hole that connects the printer's platen shaft, and protrudes into and out of bottle holes that open radially on the circumference.
When feeding the paper, a plurality of hooks have a tractor pin that fits into the paper feeding hole of the fanfold paper, are protruded around the shaft hole, and have retaining claws that protrude outward at their tips. a sprocket having a main shaft hole on its end face, and a cam portion that engages with the tractor pin and determines the protruding position of the tractor pin on the outer periphery of the sprocket; A tractor frame is provided with a paper guide provided with a slot corresponding to a portion to be fitted into a paper feed hole of the fan fold paper, and the sprocket is moved from the surface of the tractor frame on which the cam portion is provided so that its elasticity is When the elastic hook having the elastic hook is pushed into the main shaft hole of the tractor frame and the retaining pawl is hooked to the edge of the main shaft hole, the sprocket outer periphery is connected to the tractor frame so as to be rotatable around the plurality of elastic hooks. Avoid interference between the tractor pin that protrudes from the paper guide (
The paper guide is characterized in that an escape notch is provided in the slot formed in the paper guide at a portion corresponding to the tractor pin.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

First, the configuration will be explained.

FIG. 1(a) is a diagram showing the inside of the sprocket 10,
(b) is a front view. 12 is a sprocket body, which is integrally molded from a resin material such as plastic. 1
6 is a shaft hole through which a platen shaft (not shown) for rotating the sprocket 10 is inserted. 18 is a pin guide groove provided radially with respect to the shaft hole 16, into which the tractor pin 14 slides. It is movable and is disposed such that its tip can freely protrude and enter from the bottle hole 20. 22 is a protrusion;
It is integrally molded with the tractor pin 14. tractor pin 14
It is also molded from resin such as plastic.

The tip of the protrusion 22 protrudes from the bin guide groove 18 and is adapted to engage with a cam groove that is a cam portion of a tractor frame, which will be described later.

A punch hole 24 is opened in the side surface of the sprocket body 10, and is a hole for inserting a punch described later in the jig when the sprocket 10 is attached to a tractor frame using a jig described later.

Reference numeral 26 designates an elastic hook that serves as a connector, and is used to rotatably attach the sprocket 10 to the tractor frame, and has a hook-shaped retaining claw formed at its tip.

When using the sprocket IO described above, it is no longer necessary to use a pair of tractor frames, and only one tractor frame is required. As shown in FIG. 2, it has a cam groove 28 and a paper guide 30 located at the bottom of the cam groove 28. (1) In other words, a cam groove 28 is provided on the end surface of the platen t!IIjO.
28 is provided concentrically with the main shaft hole 34, and at the bottom, the tractor pin 14 should protrude from the outer periphery of the sprocket 10 (the distance from the center of the cam 128 is larger than the predetermined distance). , is arranged at the lower part of the cam 1v528, and when the tractor pin 14 is inserted into a hole for feeding the fanfold paper (not shown) guided by the paper guide 30, the tractor pin 14
A slot 38 is provided so that the paper guide 30 and the paper guide 30 do not interfere with each other. Tractor pin 14 in its slot 38
A notch 48 is provided on the platen side in a corresponding portion. To fix the sprocket lO on the tractor frame 32, the protrusion 22 of the tractor pin 14 is positioned so as to correspond to the cam groove 28 provided inside the tractor frame 32, and the elastic hook 26 of the sprocket lO is fixed on the tractor frame 32. It may be pushed into the main shaft hole 34 and fixed rotatably.

Here, a method for attaching the sprocket 10 to the tractor frame 32 will be explained.

FIG. 3 is a diagram showing the main parts near the paper feeding device of the printer.

In the same figure, the tip of the tractor pin 14 of the sprocket 10 fits into a paper feed hole (not shown) provided on both sides of the fanfold paper 36 at the bottom of the paper guide 30, and the rotational force of the sprocket 10 causes the paper to 36 in a predetermined direction. For that purpose, at least 30 paper guides
At the bottom, the tractor pin 14 protrudes from the sprocket 10, and its tip further protrudes downward from a slot 38 (see FIG. 2) provided in the paper guide 30, thereby ensuring reliable feeding of the fanfold paper 36.

However, when the print head 40 makes a carriage turn or the like, the gap between the print head 40 and the outer periphery of the sprocket 10 is set to less than 1 mm, and if the tractor pin 14 protrudes, the print head 40 and the tractor pin 10 will interfere. Therefore, the above-mentioned tractor frame 32
The shape of the cam (see FIG. 2) provided in the cam) prevents the tractor pin 14 from protruding from the outer periphery of the sprocket 10 near the printing line. Therefore, in order to attach the sprocket 10 to the tractor frame 32, the point of assembly is to make the tractor pin 14 correspond to the cam groove 28. The assembly method will be explained in detail with reference to FIG.

In FIG. 4, 42 is a jig.

First, FIG. 4A shows a state in which the sprocket 10 is set on the jig 42. The punch 44 of the jig 42 is inserted into the punch hole 24 of the sprocket 10 so that the rear part of the tractor pin 14 comes into contact with the upper part of the step 46 provided at the tip of the punch 44. In this state, none of the tractor pins 14 protrude to the outer periphery of the sprocket 10.

Next, as shown in (b), the tractor frame 32 is placed over the sprocket 10. Place the tractor frame 32 in a predetermined position and apply pressure in the direction of arrow P. Then, since the elastic hook 26 has elasticity, it is inserted into the main shaft hole 34.

At this time, since the subroquette 10 is also pushed down at the same time, the rear part of the tractor pin 14 also comes into contact with the lower part of the step 46 provided at the tip of the punch 44 of the jig 42 and moves.

The step 46 at the tip of the punch 44 allows the tractor pin 1 to be placed in a position corresponding to the cam groove 28 when the sprocket 10 with the tractor pin 14 arranged thereon is set on the tractor frame 32.
It is determined at a predetermined position on the lower stage so that the protrusion 22 of No. 4 is located. That is, the amount of protrusion from the sprocket 10 is determined for each tractor pin 14 at the bottom of the step 46 at the tip of the punch 44.

Therefore, when the tractor frame 32 is placed over the sprocket 10 and pressure is applied, the tractor pins 14 move to protrude by a predetermined amount, and their protrusions 22 engage with the cam grooves 28 to become integrated with the tractor frame 32. At this time, the elastic hook 26 is inserted, and a retaining pawl provided at the tip of the hook 26 is engaged with the other end surface of the tractor frame 32, so that it does not come off, and the assembly is completed with a single touch.

The tractor pin 14 protrudes from the outer periphery of the sprocket 10 by a predetermined amount and is attached to the tractor frame 32, but the problem here is that the tractor pin 14 corresponding to the position of the paper guide 30 has its tip as shown in FIG. protrudes from the slot 38 provided in the paper guide 30, so when the sprocket 10 is attached to the tractor frame 32, the paper guide 30, which is integrated with the tractor frame 32, gets in the way. There is no problem if the paper gutter 30 is provided separately, but it takes time and effort to install it. Therefore, a relief Φ notch 48 is provided in the slot 38 at a position corresponding to the tractor pin 14 to eliminate interference between the tractor pin 14 and the paper guide 30 at an intermediate stage when the bunch 44 projects the tractor pin 14 during installation. .

It may seem like it would be better to widen the width of the slot 38 from the beginning, but when the paper is used, the side edge of the paper will not fit into the slot 38.
The width of the slot 38 must be minimized to prevent the tractor pin 14 from falling out from the paper feed hole.

When using the sprocket formed by the method described above, the tractor frame is not made up of a single pair due to the action of the elastic hook.
Since only the outside is required, the number of parts can be reduced. Furthermore, since the sprocket and tractor pin are directly visible on the inside, when setting the fanfold paper in the paper feeding device, it is also possible to directly confirm that the tractor pins are inserted into the paper feeding holes on both sides of the fanfold paper.

Although various preferred embodiments of the present invention have been discussed above,
It goes without saying that the present invention is not limited to the above-described embodiments, and that many modifications can be made without departing from the spirit of the invention, for example, the cam groove serving as the cam portion may be a cam protrusion.

(Effect of the invention) When the paper feeding device of the invention is used, the tractor frame can be
Moreover, since the paper guide can be integrated with the tractor frame, the number of parts can be reduced. Furthermore, the escape notch provided in the slot of the paper guide makes it easy to assemble the integrated tractor frame and sprocket, resulting in significant effects such as improved work efficiency and cost reduction.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of a sprocket according to the present invention, (
b) is a front view. Fig. 2 is an exploded perspective view of a paper feeding device using a sprocket according to the present invention, Fig. 3 is a diagram showing the vicinity of the paper feeding device of a printer, and Fig. 4 is a method of attaching a sprocket to a tractor frame. FIG. 5 is an exploded perspective view of a conventional paper feeding device using a sprocket. 12...Tractor frame, 14...Tractor pin, 16...Shaft hole, 26...Elastic hook.

Claims (1)

[Claims] 1. It has a shaft hole that connects the printer's platen shaft, and has a tractor pin that protrudes into and out of pin holes that open radially on the circumference, and that fits into the paper feed hole of fanfold paper when feeding paper. , a sprocket having a plurality of hooks protruding around the shaft hole and having a retaining claw protruding outward at the tip; and a sprocket having a main shaft hole on an end face and engaging with the tractor pin; A cam part is formed to determine the protrusion/input position of the pin on the outer periphery of the sprocket, and a slot is provided below the cam part corresponding to the part of the tractor pin that fits into the paper feeding hole of the fanfold paper. a tractor frame forming a guide, the sprocket is pushed into the main shaft hole of the tractor frame from the surface where the cam portion of the tractor frame is provided, and the elastic hook thereof is pushed into the main shaft hole of the tractor frame, and the retaining claw is pushed into the main shaft hole edge of the main shaft hole. A slot is drilled in the paper guide to avoid interference between the tractor pin protruding from the outer periphery of the sprocket and the paper guide when the paper guide is connected to the tractor frame so that it can rotate freely around multiple elastic hooks. A paper feeding device for a printer, characterized in that a relief notch is provided in a portion corresponding to a tractor pin.