JPS6234776Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper end detection mechanism for a printer, and particularly relates to the arrangement of detection elements.

Conventionally, a paper feeding mechanism such as a tractor or a sprocket that feeds the paper by engaging with a feed hole in the printing paper is placed on the paper pulling side with respect to the printing platen to pull and feed the paper. A printer that can be moved freely in the paper width direction at any time depending on the size or widthwise movement of the paper is well known. The main parts of an example of such a printer are schematically illustrated in FIG. 1 of the drawings. In this figure, each code is 1 for printing platen, 2 for printing paper,
Reference numeral 3 indicates a paper feed tractor, 4 indicates a paper guide, and 5 indicates a printing mechanism. The tractor 3 is disposed on the paper pulling side with respect to the printing platen 1, that is, on the downstream side of the paper path, and a pin engages with a feed hole of the paper 2 to pull and feed the paper in the direction of arrows A to B. The paper guide 4 is provided on the front surface (printing surface) side of the paper 2 on the paper supply side, that is, on the front side of the paper path with respect to the printing platen 1 , and guides the paper 2 to the printing platen 1 . The paper 2 is generally of different sizes depending on the purpose, or even if the paper size is the same, the paper is moved in the width direction to change the printing position in the paper width direction. In such a case, as a matter of course, the paper feed hole will shift, so the tractor 3 is configured to be able to move freely in the paper width direction (direction perpendicular to the plane of the drawing) at any time accordingly.

As shown in FIG. 1, the paper end detection mechanism in the printer described above generally includes a micro switch 6 fixedly attached to a frame or the like on the paper supply side (arrow A side) of the printing platen 1 so as to be able to swing freely. The tip of the switch lever 7 provided in the paper guide 4 is configured to look into a hole 8 made in the paper guide 4. When the paper 2 is present in the hole 8, the switch lever 7 is pushed down by the paper and the micro switch 6 is in the ON state, and when the end of the paper passes through the hole 8, the switch lever 7 moves as shown by the dotted line. When released, the micro switch 6 is turned OFF, and the paper end is detected. However, in the conventional mechanism in which the detection element is fixedly installed in this way, when the paper size (width dimension) changes or the paper is moved in the width direction, the switch lever 7 may be moved depending on the extent of the change. There is a problem in that the paper comes off from the paper, making it impossible to detect the end of the paper, thereby limiting usable paper sizes and paper movement.

Therefore, an object of the present invention is to solve such problems, that is, to provide a paper end detection mechanism that can detect paper end regardless of paper size or paper movement.

The paper end detection mechanism according to the present invention generally includes a paper end detection element provided in a paper feeding mechanism such as the above-mentioned tractor so as to be movable integrally therewith.

Hereinafter, the present invention will be explained based on an embodiment with reference to FIG. 2 of the drawings.

FIG. 2 is a diagram showing an embodiment of the paper end detection mechanism according to the present invention, together with the main parts of the printer, in correspondence with FIG. 1, and the same parts are designated by the same reference numerals. Further, the basic configuration and operation of the printer are also as described above. A feature of the paper end detection mechanism of the present invention is that the micro switch 9 and the switch lever 10, which are detection elements, are provided in the housing of the tractor 3 and can be moved integrally therewith. The switch lever 10 is swingably attached to the micro switch 9, and its tip is brought into contact with the back surface of the paper on the supply side (opposite the print surface) with respect to the printing platen 1. A concave stepped portion 12 is formed in a portion of the paper guide 11 that corresponds to the contact portion of the switch lever. This will be discussed further later. When the paper 2 is present at the stepped portion 12, the switch lever 10 is pushed up by the paper 2 and the micro switch 9 is in the ON state. When the end of the paper passes through the stepped portion 12, the switch lever 10 falls into the stepped portion 12 due to its own weight as shown by the dotted line, the micro switch 9 is turned off, and the end of the paper is detected.

As described above, the detection elements 9 and 10 are connected to the tractor 9.
Therefore, when the tractor 3 is moved according to the paper size or paper movement, the detection elements 9 and 10 are
The paper also moves integrally with this, making it possible to always detect the paper end.

Next, the stepped portion 12 for the paper size 11 described above is for allowing the switch lever 10 to fall down when the paper end is detected. If you just want to drop it in, you can just make a hole 8 as in the conventional example shown in FIG. However, in the case of the present invention, since the switch lever 10 moves along with the tractor 3 in the paper width direction, the holes must be made elongated to accommodate this movement.
There is no problem if the length of the hole is relatively short, but if it is too long, a problem arises in that when feeding narrow paper from the direction of arrow A, the starting end of the paper gets caught in the elongated hole, making feeding impossible. On the other hand, in the present invention, since the concave stepped portion is used instead of a hole, the above-mentioned problem does not occur and the starting edge of the paper is guided smoothly. Moreover, the existence of the concave stepped portion makes it possible to ensure a swinging motion of the switch lever with a large amplitude, so that reliable paper end detection is possible. Note that the stepped portion 12 may be formed to have a length necessary for moving the switch lever 10 in the paper width direction.
Alternatively, it may be formed over the entire width of the paper guide 11 without any problem.

As described above, the paper end detection mechanism of the present invention moves the paper end detection mechanism by moving the paper feed mechanism such as a tractor according to the paper size and paper movement, making it easy to change the size and move the paper. It is highly practical as it also prevents users from forgetting to operate it.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional paper end detection mechanism together with the main part of a printer, and FIG. 2 is a schematic diagram showing an embodiment of the paper end detection mechanism according to the present invention together with the main part of a printer. 1... Print platen, 2... Print paper, 3...
Paper feed tractor, 9...Micro switch, 1
0: switch lever, 11: paper guide, 1
2...Concave step portion.

Claims (1)

[Scope of Claim for Utility Model Registration] A paper feed mechanism that feeds the paper by engaging with a feed hole in the printing paper is disposed on the downstream side of the paper path with respect to the printing platen so as to be movable at any time in the width direction of the printing paper. A paper end detection mechanism in a printer in which a paper guide that guides the printing paper to the printing platen is provided on the front side of the printing paper on the front side of the paper path with respect to the printing platen, and is a swingable paper guide whose leading end abuts the printing paper 2. A paper end detection element having a switch lever 10 moves integrally with the paper feed mechanism, and the tip of the switch lever contacts the back side of the printing paper at a position opposite to the paper guide 11. The paper guide 11 is provided with a recessed stepped portion 12 into which the tip of the switch lever 10 falls when the trailing edge of the printing paper passes the tip of the switch lever 10. Features printer paper end detection mechanism.