JPS6220289Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a paper feeding device for a printer, and more specifically, a printer having a platen roll and a pair of sprocket wheels for feeding continuous slip paper (sprocket paper) on the same axis. The present invention relates to a paper feeding device (hereinafter referred to as a pin platen device).

Conventionally, there are various types of paper feeding devices for printers, but in particular, in printers that use preformatted paper for the purpose of issuing slips, etc., in order to ensure accuracy in paper feeding, paper feeding devices are used for printing paper. It is necessary to make a sprocket hole and feed the paper using the sprocket foil. In addition, when handling slips, it is not allowed to feed the paper excessively when cutting the paper after printing or when printing the next slip, so the commonly used sprocket device for paper feeding should be moved from the printing position. It is not possible to use a paper feeding device that is placed at the rear or front.

For this reason, a paper feeding device (pin platen device) with sprocket foils attached to both ends of the platen roll was adopted, but this device had major problems in practical terms as described below. .

In a pin platen device, if sprocket oil with pin protrusions on the outer periphery is fixed in advance to a predetermined position at both ends of the platen roll with fixing means such as screws or stop pins, the problem may occur due to variations in the machining accuracy or assembly accuracy of the parts. As a result, the dimension between the sprocket foils changes, resulting in a discrepancy between the dimension between the marginal punches of the sprocket paper, and
This caused quality problems such as a decrease in paper feeding ability and the inability to set sprocket paper.

To prevent such troubles, many man-hours were spent making delicate adjustments when assembling the pin platen device. By the way, the tolerance of the dimension between marginal punches specified by JIS is ±0.1mm, so when actually assembling the pin platen device, the distance between the pins must be ±0.1mm.
It has been adjusted to a target of 0.05mm. In addition, to further prevent the above-mentioned troubles, a common method is to make one side of the marginal punch of the sprocket paper an elongated hole (4 mm x 6 mm), but if the place where the printer is installed is fully air-conditioned. As printers expand from modern computer rooms to general offices and even storefronts that are directly exposed to outside air, printers that can handle large changes in humidity environments (usually around 10 to 85%) are required. General paper expands and contracts in size in proportion to its moisture content, and in the case of high-quality paper, the expansion and contraction rate is approximately 0.2%/10%RH (paper dimensions change by approximately 0.2% for a change in relative humidity of 10%). . Therefore, in the case of paper with a paper width of 10 inches (254 mm), the dimension l between marginal punches is 9.5'' (241.3 mm), and if the humidity changes from the standard 45% to 85%, the amount of change in l is △ l is △l = 241.3 x (85 - 45) / 10 x 0.002 = 1.93 (mm).On the other hand, the diameter of the pin protrusion on the sprocket foil is usually about 3.8 ± 0.2 mm, The allowable dimensional change δ is δ = 6-3.8/2 = 1.1 (mm), and the above change △l cannot be absorbed.On the other hand, if the elongated hole size of the paper is 6.mm Although it is possible to expand the size to 8 to 9 mm, this method has the disadvantage that the paper is not distributed in the general market, and the strength of the paper around the hole decreases, causing problems such as tearing of the hole during feeding. is expected, and cannot be an appropriate countermeasure.

The object of the present invention is to provide a paper feeding device that enables the axial position adjustment of a sprocket wheel disposed at the end of a platen, and has a mechanism that absorbs rotational play of the sprocket wheel.
This ensures accurate printing position, eliminates the need for extra paper feeding, reduces the precision of paper feeding device parts and assembly adjustments, and allows commonly available sprocket paper to be used without trouble in a wide range of usage environments. Our goal is to provide printers that can.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing the entire paper feeding device according to the present invention, in which sprockets 2 and 2a are arranged on both sides of a platen 1.

The sprocket foil 2a is attached to the platen shaft 1a with a fastening member (not shown) such as a screw or a stop pin.
is fixed in place. As shown in FIG. 2, a rotation stopper pin 8 is press-fitted into the sprocket wheel 2, and a steel ball 9, a compression spring 10, and a set screw 11 are built into the sprocket wheel 2 in a direction substantially perpendicular to the rotation stopper pin 8. The rotation stopper pin 8 has one end attached to the platen shaft 1a.
A slot 1 protrudes from the side and is provided on the platen shaft 1a.
b. The steel ball 9 is compressed by a compression spring 10 into another slot 1c formed on the platen shaft 1a, urging the sprocket foil 2 counterclockwise with respect to the platen shaft 1a. Therefore, the backlash that occurs at the engagement portion between the rotation stopper pin 8 and the slot 1b is focused and positioned in one direction (to the right in the drawing). If the direction of rotation of the sprocket wheel during normal paper feeding operation is clockwise, this backlash will not pose a functional problem. The slots 1b and 1c are both elongated holes in the axial direction, allowing the sprocket foil 2 to slide by the amount of expansion and contraction Δl+α (α≈2 to 3 mm) of the sprocket paper mentioned above. 14 is a sprocket paper, and 14a and 14b are marginal punch holes.

The axial position of the sprocket foil 2 on the platen shaft 1a is defined by the holding member 3. Third
4, the holding member 3 screwed into the threaded portion 4a has a U-shaped arm portion with respect to the guide shaft 4 supported by the machine frame (FIG. 1, 12) with a defined axial position. 31 and 32 on side 2 of sprocket foil 2
It is held closely between 1 and 22. Further, the U-shaped arms 31 and 32 engage with the sprocket wheel 2 to maintain the posture of the holding member 3 itself.

When the guide shaft 4 is rotated, the holding member 3 slides in the axial direction due to the screw effect of the threaded portion, and the sprocket foil 2 also slides on the platen shaft 1a. The holding member 3 is threadedly engaged with the threaded portion 4a of the guide shaft 4, and also has an engaging portion 3a with a smaller outer diameter portion 4b of the guide shaft 4.
This prevents chattering when the holding member 3 slides, and also ensures the perpendicularity of the arm portions 31, 32 to the guide shaft 4 and the platen shaft 1a. The guide shaft 4 is equipped with a gear train on the outside of the machine frame 12. In FIG. 5, a gear 5 fixed to a guide shaft 4 is connected to a knob wheel 7 via an intermediate gear 6. The rotation of the knob wheel 7 is transmitted to the guide shaft 4 via a gear 7a provided on the knob wheel 7, an intermediate gear 6, and a gear 5. Therefore, by rotating the knob wheel 7, the axial position of the sprocket wheel 2 changes as the guide shaft 4 rotates and the holding member 3 slides. The knob wheel 7 is made as large as possible while taking into account the space available with the case for housing the printer, the appearance, etc., and knurling is applied to the outer periphery to reduce rotational force and improve usability.

If the humidity changes from the state in which the sprocket paper is set on the pin platen device according to the present invention in the current humidity environment, the paper will expand and contract, and the gap between the marginal punch and the pin protrusion on the sprocket foil as shown in Fig. 6a or A biting phenomenon as shown in FIG. 6b occurs. However, in the case of Fig. 6a, the sprocket foil 2 is moved in the direction of the arrow 63, and the
In this case, the jamming phenomenon can be eliminated by correcting the movement in the direction of the arrow 64, and troubles such as a decrease in paper feeding ability and tearing of the marginal punch can be avoided. Furthermore, when setting the sprocket paper, if the positions of the marginal punch and the pin protrusion are misaligned, the operator can visually check and make adjustments, thereby preventing troubles in which the paper cannot be set.

The marginal punch 62 of the sprocket paper 60 is a pin protrusion on the sprocket foil 2. In FIGS. 1 and 4, the indicator 13 fixed to the holding member 3 is disposed at a position to indicate the axial position of the pin protrusion of the sprocket wheel 2, and the indicator 13 is arranged at a position to indicate the axial position of the pin protrusion of the sprocket wheel 2, especially when setting the paper. Use this as a guideline when making adjustments in advance depending on the paper situation. Therefore, the pointer portion 13a of the indicator 13 is arranged as close as possible to the paper insertion path.

FIG. 7 shows another embodiment of the present invention, in which both sprockets on both sides are slidable. Holding member 7
1 and 72, the right side 73a is a right-hand thread, and the left side 73b is a left-hand thread, so that the sprocket wheels 74 and 75 can be connected to each other without changing the position of the paper relative to the machine frame. The interval can be adjusted. That is, by rotating the guide shaft 73, the gap between the two can be simultaneously moved in a direction that widens or narrows, and a large adjustment margin can be obtained with a slight rotation of the knob wheel 76.

As described above, the sprocket wheel is prevented from rotating and slidably locked on the platen shaft, and the play between the sprocket oil and the platen shaft is regulated so that it always occurs in one direction. By adopting a configuration that allows fine adjustment of the sprocket wheel in the direction of the platen axis, it is possible to virtually eliminate any play in the paper feeding direction of the sprocket wheel, which is adjusted to match the sprocket hole of the printing paper on the platen, thereby adjusting the printing position relative to the printing paper. It has become possible to calculate this very accurately. In addition, it is easy to make optimal adjustments according to paper conditions, improving usability without affecting paper feeding performance.
It is possible to loosen the precision of individual parts or assembling them, making it possible to realize an inexpensive printer. Furthermore, it is possible to realize a pin platen device that can use commonly available sprocket paper in a wider range of environments, and the present invention has great effects.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the present invention, and FIGS. 2 to 6 are partial views of the embodiment. FIG. 7 shows another embodiment of the invention. In the figure, 1 is a platen, 2 is a slidable sprocket foil, 3 is a holding member, 4 is a guide shaft, 7 is a knob wheel, and 14 is a sprocket paper.

Claims (1)

[Claims for Utility Model Registration] A platen shaft with a groove formed in the longitudinal direction of the shaft,
The platen has a rotation stopper pin that engages with the groove, and a mechanism that restricts a gap generated between the rotation stopper pin and the groove so that it always exists in one direction, and is prevented from rotating and slidable relative to the platen shaft. a sprocket wheel rotatably supported; a guide shaft disposed parallel to the platen shaft and having a threaded portion; a through hole having a female threaded portion that engages with the threaded portion of the guide shaft; and the sprocket. 1. A paper feeding device for a printer, comprising a holding member formed with a protrusion for holding a foil.