JPS5855910B2 - printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printer that can feed paper uniformly.

FIG. 1 is a diagram showing a conventional paper feeding section of a printer having two pinch rollers.

Such pinch roller shafts have been widely used and have no technical problems.

However, in printers that use various types of paper, such as typewriters and computer printers, the number of pinch rollers should be 3/T or more.

Figure 2 shows a pinch roller shaft with three pinch rollers, which is also widely used.

However, a drawback of this method is that the central pinch roller 9 tends to be lifted up due to the bending of the shaft 11, as shown in FIG.

The stronger the springs 14 and 15, the more the shaft 1 bends △X.
1, the thinner it is, and the longer the shaft length tl, the thicker it is.

Since the forces of the springs 14 and 15 are determined as necessary, conventionally the shaft 11 is used in order to minimize this bending.
The diameter was increased.

However, a thick shaft has a large amount of inertia, is not suitable for high-speed drive, and is expensive.

Furthermore, if the shaft of a typewriter is long and even if the shaft is made thicker, there will still be some floating in the center, making it impossible to feed the paper evenly, use the unit shown in Figure 1 or Figure 2. There are many cases where several are used side by side.

In view of these points, the present invention provides a means for pressing three pinch rollers against a platen with uniform force while using a relatively thin pitch roller shaft.

FIG. 4 shows a pinch roller according to the present invention.

The three pinch rollers 16, 17, 18 are on the same shaft 19, and levers 20 and 22 supporting the shaft 19 are located inside the pinch rollers 16, 18, respectively.

Springs 21 and 23 are applied to the levers 20 and 22, respectively, and the forces applied to the fulcrums 20' and 22' are Wl and W.
It is 2.

Since the lever and spring have the same shape, they are W1W2.

The positions of the fulcrums 20' and 22' on the shaft 19 are located outside the middle of each pinch roller, as shown in FIG.

The force W1 by the lever 20 is applied to the pinch rollers 16 and 17 by 2/3 and 1/3, respectively, and the force W2 by the lever 22 is applied to the pinch rollers 17 and 18 by 1/3 and 2/3, respectively.
It is set to multiply by 73rd place.

Therefore, the forces with which the three pinch rollers 16, 17, and 18 push the platen are approximately equal.

According to the present invention, even if a relatively thin shaft 19 is used, the Vinci roller 11 does not float up.

Moreover, even if the total length of the shaft becomes considerably long, the distribution of force can be kept almost constant.

FIG. 5 is a perspective view of an application example that further takes advantage of the features of the present invention.
FIG. 6 is a side view thereof.

A commonly used method is to provide pinch rollers at two locations on the circumference of the platen 37 in order to make paper feeding by the platen more accurate, but by applying the present invention, it is possible to use six or more pinch rollers with the same pressure. Can be pressed against the platen.

In Fig. 5, there are three pinch rollers on each of the shafts 30 and 31, and the fulcrums are 32', 33'EI and 3, respectively.
2'' and 33'', and their positional relationship is the same as that shown in FIG.

The arm 32, which has fulcrums 32' and 32'', has another fulcrum 32'' 7b at its center, and the lever 3 is centered around this point.
It is rotatable relative to 5.

The lever 35 is rotatable around 35', and the other end 35'' is hung by a spring 36.

As can be seen in FIG. 6, the force of spring 36 is applied via lever 35 to fulcrum 32''.

Since the fulcrums 32' and 32'' on the arm 32 are equidistant from the fulcrum 32'' (L3), the forces W3 and W4 pushing the pinch rollers 24 and 27 and the pinch roller 37 are always the same.

The other arm 33 shown in FIG. Lever 34. The spring 37 is attached to the arm 32. lever 35, spring 36
It has the same shape as .

Therefore, the two springs 36 and 37 apply force to the six pinch rollers to push the platen 37, but the pushing force is always uniform even though the shafts 30 and 31 are quite thin and long.

[Brief explanation of drawings]

Figures 1 and 2 are conventional examples, Figure 3 is a plan view of Figure 2, and Figure 4 is a plan view of Figure 2.
The figure shows one example of the present invention, FIG. 5 is another example, and FIG. 6 is a side view thereof. 16.17,18...Pinch roller, 20,2
2... Lever 21, 23... Sfring.

Claims (1)

[Claims] 1. A first pinch roller is provided on a shaft disposed at a position facing a platen for paper feeding, and a second pinch roller and a third pitch roller are provided on the left and right sides of the first pinch roller. 2nd and 1st. A printer characterized in that a fulcrum is set at a point approximately 2°1 between the third pinch rollers, and a spring for pressing the platen is attached to each of the fulcrums to uniformly press the pinch rollers against the platen.