JPS6340675B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a platen mechanism in a printing device, and more particularly to a platen mechanism with a cutter that handles printing paper fed by a sprocket pin.

In impact type printing devices, a platen mechanism is known in which printing paper having sprocket holes is hooked onto a pin provided on a platen and fed.

A known platen mechanism is shown in FIG. A sprocket pin 2 is provided on the platen 1, and a cutter 4 is provided near the platen 1.
The sprocket hole of the printing paper 3 is hooked, and the platen 1 rotates in the direction a, thereby feeding the paper 3 in the direction c. A printing head is mounted on a known carriage that moves in the axial direction of the platen 1, and by driving the carriage with a pulse motor or the like, an impact is applied to the printing paper 3 through the ink ribbon, and printing is performed. .

In addition, with recent technology, there is a need to print on forms with various paper widths using the same printing device, and it is also necessary to place the cutter 4 as close to the platen 1 as possible in order to avoid wasting printing paper. It is being done.

However, in the above-mentioned known printing device,
Since the pins are directly attached to the platen 1, the spacing between the pins on the platen 1 is fixed, making it impossible to use printing paper of any width with the same printing device.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and by making it possible to print from a position close to the leading edge of printing paper, it is possible to reduce waste of paper and to print with the same printing device. An object of the present invention is to provide a platen mechanism capable of handling printing paper of arbitrary width.

The present invention provides a platen and a paper feed wheel independently, and by moving the paper feed wheel,
In addition to feeding sheets of arbitrary width, a cutter is provided at a position very close to the printing position to cut the printed sheets. The paper feed wheel has a pin that can move in and out, so even if the paper is cut very close to the printing position, the paper can continue to be fed. In this way, it is possible to save printing paper, and by making the platen and paper feed wheel independent and moving the paper feed wheel,
It is possible to feed paper of any width.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIGS. 2 and 3, the platen 5 has a substantially trapezoidal shape, and both ends thereof are fixed to a printing mechanism (not shown). Print paper 3 is set in front of this platen 5 and fed. A pair of sprocket wheels 6 behind the platen 5 and having a diameter larger than the width l of the bottom surface of the platen 5.
will be placed. The sprocket wheel 6 is movable on the spline shaft 7, and is fixed at any position on the spline shaft 7 by a lever 11 hooked between the spline shaft 7 and the fixed shaft 10. obtain. That is, by moving the lever 11 according to the width of the printing paper 3 set on the platen 5 and setting the adjustment lever 9, the sprocket wheel 6 is fixed at a predetermined position. Although the mechanism for fixing the sprocket wheel 6 and the adjustment lever 9 is not shown in detail, it is accomplished by known means as follows. For example, the adjusting lever 9 has its fulcrum on the lever 11 and forms a friction clutch on its surface in contact with the fixed shaft 10. Normally, the lever 11 is fixed on the fixed shaft 10 by being pressed against the fixed shaft 10 by a spring. During movement, the adjustment lever 9 is pulled away from the fixed shaft 10 against the spring to release the fixation between the lever 11 and the fixed shaft 10.

The lever 11 also fixes the sprocket wheel 6 on the spline shaft 7, and at the same time prevents the rotation of a positive cam that controls the movement of the pin 2 inside the sprocket wheel 6, which will be described later.

The sprocket wheel 6 is provided with a sprocket that can go in and out, and its going in and out is controlled by a known positive cam mechanism as shown by the two-dot chain line in FIG. This can be achieved, for example, by the technique disclosed in US Pat. No. 2,047,233.

Further, a paper presser 8 is provided on the upper part of the sprocket wheel 6, and presses the printing paper 3 so that the paper 3 fed from the sprocket pin 2 does not come out of the sprocket hole. Furthermore, a cutter 4 is provided at the rear of the paper presser 8, that is, immediately after the position where the sprocket hole and the sprocket pin disengage, and cuts the printing paper 3 as close as possible to the printing position, thereby reducing waste of paper. is decreasing.

Next, to describe the operation, the paper 3 first hits the pin 2 on the lower side of the sprocket wheel 6, and
Next, it passes over the front surface of the stationary platen and again catches on the upper pin 2 of the sprocket wheel 6. Above the sprocket, the printing paper 3 is held down by a paper presser 8 and fed so that it does not come off the pins.
After printing is completed, the paper 3 is cut by the cutter 4, but the paper 3 is cut by the cutter 4.
Since the feeding holes of the set are hooked, continuous feeding is possible.

As explained above, according to the present invention, since the sprocket wheel is movable, printing paper having various widths can be guided onto the platen. In addition, a pair of sprocket wheels are provided behind the platen, and sprocket pins that can protrude from the outer periphery of these wheels are used to hook the sprockets of the printing paper at the front and rear ends of the platen, making the platen mechanism simple and compact. become. Furthermore, since the cutter is disposed immediately after the position where the sprocket hole and the sprocket pin are disengaged, it is possible to eliminate waste of printing paper.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a conventional platen mechanism, FIG. 2 is a perspective view of the platen mechanism for explaining an embodiment of the present invention, and FIG. 3 is a side sectional view of FIG. 2. 2 is a pin, 3 is a printing paper, 4 is a cutter, 5 is a platen, 6 is a sprocket wheel, 7 is a spline shaft, 8 is a paper presser, 9 is an adjustment lever, 10
is a fixed shaft.

Claims (1)

[Claims] 1 At least two sprocket wheels movable parallel to the longitudinal direction of the platen, engagement between sprocket pins provided on the sprocket wheels and sprocket holes provided on both sides of the printing paper that engage with the sprocket pins. In a platen mechanism equipped with a cutter provided near the position where the sprocket pin is disengaged, the sprocket pin can be reciprocated with respect to the center of rotation of the sprocket wheel, and when the sprocket wheel rotates, The position where the sprocket wheel faces and contacts the platen is located inside the circumferential surface of the sprocket wheel, and the printing paper before and after the position where the sprocket wheel faces the platen In the position where it engages,
A platen mechanism characterized in that the platen mechanism is located outside the circumferential surface of the sprocket wheel.