JPS647875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper feeding mechanism for data communication printers, line printers, XY plotters, typewriters, etc. that use perforated paper. The purpose is to tighten the rules.

In the conventional paper feeding mechanism of this type, a pair of left and right pin tractors were placed behind the platen and engaged with the paper on the forward feeding side of the platen, but with this method, there was a special problem when feeding the printing paper in the forward direction. There is no problem, but if you try to feed the paper in the opposite direction, the paper will be forced into a narrow path with a lot of frictional resistance, and the paper will easily bend, making it extremely difficult to expect normal operation. In addition, even if the reverse feed is performed normally, the amount of feed will inevitably deviate from the forward feed due to the play between the paper feed hole and the pin tractor. This is extremely inconvenient for devices that require a large feed rate. This is exactly the same in the case of a feeding mechanism using a so-called sprocket wheel, and herein, a device including a sprocket wheel that drives the paper by rotation of a pin is called a pin tractor.

As a means to solve the above-mentioned conventional problems, first, a method can be considered in which the pin tractor and the platen are simultaneously driven in the forward or reverse direction. Although this method can prevent the paper from bending during reverse direction feeding, if there is even a slight difference in the feeding pitch between the pin tractor and the platen, this will accumulate and cause the paper to sag between the two.
Conversely, excessive tension is applied to the paper, leading to damage from the feed hole. To prevent this, it is possible to free the platen and drive only the pin tractor when feeding in the forward direction, and to free the pin tractor and drive only the platen when feeding in the reverse direction. A switching mechanism is required, making the structure complex and expensive, and also poses problems in reliability.

Alternatively, a method can be considered in which pin tractors are installed on both the front and back sides of the platen through which paper enters and exits, and the pin tractors are interlocked with each other to drive both in the forward and reverse directions, but this increases the bulk, especially the height, of the entire device, and Insertion becomes complicated, and the entire device including the drive system becomes complicated and expensive, which is disadvantageous economically.

Unlike these methods, the present invention achieves the desired objective from a new perspective of using the back side of the pin tractor, which was previously idle, for paper feeding. To provide a paper feeding mechanism that can conveniently and accurately feed paper in any forward or reverse direction at any time without complicating the structure.

The invention will now be described in detail with reference to the accompanying drawings, in which one embodiment is shown.

In FIG. 1, numeral 1 is a platen that receives printing force;
2 is a pinch roller, which rotates the platen at a fixed angle in the case of general paper without a sprocket hole and feeds the paper by the frictional force generated by the pressure of the pinch roller 2; When feeding the paper 3, the pinch roller 2 is separated from the platen 1 (FIG. 3), and the platen 1 does not actively feed the paper 3 even though it rotates. Reference numeral 4 indicates feed holes arranged at a constant pitch on both side edges of the paper 3.

Reference numeral 5 denotes a tractor pin assembly including a tractor pin 6 that engages with the feed hole 4 of the paper, and is wound around each pair of pulleys on the side of the paper 3, that is, a driving pulley 7 and a driven pulley 8. The pulleys 7 and 8 are each rotatably supported by a supporting metal fitting 10 at a constant pitch. Reference numeral 11 denotes a square shaft for rotating the left and right drive pulleys 7, which is rotated in any direction forward or reverse by an appropriate drive means (not shown).
The shaft 12 supports the left and right driven pulleys 8, and both ends are fixed to the tips of a swing arm 13 that is rotatably supported relative to the square shaft 11.

The support fitting 10 can slide left and right on the shafts 11 and 12 and is fixed at a required position. Reference numerals 14 and 15 denote paper press plates hinged to both upper and lower edges of the support fitting 10 to prevent the paper 3 from floating up. 16 is connected at both ends to both presser plates 14 and 15, and both presser plates 14 and 1
5 shows a tension coil spring holding 5 in the operative position shown.

In this feeding mechanism, a tension roller 17 is also disposed at an intermediate lower side between the pin tractor T having the above structure and the platen 1. A shaft 18 rotatably supports the roller 17, and both ends thereof are fixed to the tips of swing levers 19 pivotally supported on both sides of a printer frame (not shown).
20 is a tension spring that biases the lever 19 clockwise, and the roller 17 contacts the adjacent portion of the paper 3 due to the elasticity of the spring 20 to apply a certain tension to the paper.

In this feeding mechanism, the paper 3 is inserted into the feed hole 4 by the pin 6 on the back side of the tractor, as shown in Figures 1 and 2.
After passing through the tension roller 17 and platen 1, the pin 6 on the front side of the tractor is engaged, and when the square shaft 11 rotates in the forward or reverse direction, the pin on the front side of the paper 3 engages with the tractor. The mating part and the part engaging the back pin tractor move in opposite directions. That is, the paper 3 is driven by the pin tractor T at both the front and rear positions when it passes through the platen 1, which is the printing section, and is reliably and smoothly moved in either the forward or reverse direction under the tension effect of the tension roller 17. be transported.

Tension roller 17 serves to apply constant tension to the paper and to ensure that the paper is always fed the correct amount in both forward and reverse directions. In other words, if the tension roller 17 is missing, the length from the back side pin of the pin tractor T through the platen 1 to the front side pin must be an exact multiple of the pitch of the feed hole 4 or the tractor pin 6, otherwise the paper may become loose or become excessively large. This requires extremely high accuracy in the relative position and dimensions of the platen and pin tractor, and requires advanced adjustment technology.However, in the main feeding mechanism, a tension roller 17 is provided to properly tension the paper. Since the tension is applied to the paper, the paper can always be correctly engaged with the pins on both the front and back sides of the pin tractor. Furthermore, even if there is play due to the diameter difference between the sprocket hole 4 and the tractor pin 6, as shown in FIG. Since the tractor pin 6 engages with the tractor pin 6, the paper can be fed reliably without any play in either the forward or reverse direction.
Even if forward and reverse feeding is repeated alternately, the correct feed amount is always guaranteed.

Next, referring to FIG. 3, the procedure for loading paper in this embodiment will be explained. That is, first, by pulling up the left and right swinging arms 13 and swinging them clockwise about the square shaft 11, the left and right pin tractors T are raised as shown in FIG. 3A. next,
The paper presser plate on the platen side of both pin tractors, that is, the back paper presser plate 15 is opened, and the feed hole of the paper 3 is hooked to the rear tractor pin, the paper presser plate 15 is brought down, and one end of the paper is guided to the platen 1. Next, arm 1
3, return the left and right pin tractors to their normal positions as shown in Figure 3B, open the upper paper holding plate 14, apply appropriate tension to the paper, hook the feed hole to the front tractor pin, and finally Paper press plate 14
Close it to finish loading the paper.

As is clear from the above description, according to the present invention, the direction of paper feed can be reversed at any time without the need for a particularly complex mechanism, high precision processing, or advanced adjustment technology. A paper feed mechanism that can always feed paper extremely accurately and smoothly in any direction is obtained, and by applying this to various printers, typewriters, XY plotters, etc., great practical benefits can be obtained.

Note that the specific shape and configuration of the mechanism of the present invention is not limited to the above-mentioned embodiments, and various changes may be made to the form and configuration of the pin tractor and other parts as necessary, and the patent rights of the present invention do not cover such changes. The present invention extends to all paper feeding mechanisms defined in the claims above, including variations thereof.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts of an embodiment of the present invention.
FIG. 2 is a schematic side view of the same, and also shows the state of engagement between the paper and the pins on both sides of the pin tractor. FIGS. 3A and 3B are schematic side views showing how to attach paper. 1: Platen, 3: Paper with sprocket holes, 4: Sprocket holes, T: Pin tractor, 10: Support bracket, 1
3: Swing arm, 14, 15: Paper press plate, 17:
tension roller.

Claims (1)

[Claims] 1. A paper feed mechanism using paper with feed holes, a paper press plate hinged to both the upper and lower edges of the support fitting of each pin tractor so that the paper can be engaged with both the front and back sides of each pin tractor, and the above-mentioned A pin tractor is provided around a fixed rotating shaft so as to be rotatable in a direction substantially perpendicular to the rotating shaft of a rotatable platen, so that the distance between the pin tractor and the platen can be changed. paper feed mechanism.