JPH0532347A - Sheet feed device for printer - Google Patents

Abstract

PURPOSE:To prevent a gear lock or a gear fracture by providing a low rigidity section capable of flexible deformation against the reaction of a partner gear between at least one of drive and driven gears, and the shaft concerned. CONSTITUTION:A low rigidity section 20 capable of flexible deformation against the reaction of partner drive and driven gears 32 and 12 is provided between at least one of said gears 32 and 12, and the concerned shaft 11 or 31. The low rigidity section 20 comprises a hollow cylindrical section between the drive gear 12 and the boss section 13 thereof, or a thin-wall section, and is integrated with both sections 12 and 13. The material of the hollow cylindrical section is synthetic resin. According to this construction, even when tooth tops of both gears 12 and 32 come in contact with each other at the time of gearing, or tooth tops and roots are deeply engaged due to the axial changes of both shafts, a gear lock and a tooth fracture can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for a printer having a feed roller and a pinch roller.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional structure of a paper feeding device of a printer. In the figure, reference numeral 10 denotes a drive unit including a drive shaft 11, a drive gear 12, and a feed roller 15,
It is rotated by a motor (not shown). Feed roller 15
Are fixed to the drive shaft 11 or integrally formed. The drive gear 12 has a boss portion 13, for example, a screw 1
It is fixed to the drive shaft 11 by 4. On the other hand, 30 is a driven portion, which is a driven shaft 31, a driven gear 32, and a pinch roller 35.
Consists of.

If the axes Z1 of the drive shaft 11 and the axis Z3 of the driven shaft 31 are kept constant by meshing the gears 12 and 32 with each other, the rollers 15 and 35 are rotated by rotating the drive shaft 11. It is possible to feed the paper in a predetermined direction while synchronously rotating.

By the way, in the printer, it is necessary to adjust the gap (head gap) between the print head and the platen in accordance with the thickness of the applied paper. At this time, both shafts 11,
The relative position of 31 is changed to disengage the gears 12 and 32 from each other, and the gears are engaged again after the head gap is adjusted. To change the relative positions of the two shafts 11 and 31, for example, as shown in FIG. 3, the axis Z1 is inclined to open the space between the feed roller 15 and the pinch roller 35. This relative position change is often performed automatically by using cam movement.

[0005]

By the way, according to the above-mentioned conventional structure, when the gears 12 and 32 are meshed with each other, the tooth crests come into contact with each other to be in a so-called locked state, and in the worst case, tooth spillage may occur. There are problems that arise. Even if the tooth crests and the troughs are meshed with each other, if the distance between the axes Z1 and Z3 of the shafts 11 and 31 becomes smaller than a predetermined distance due to mechanical deformation or the like, the same problem occurs.

One solution to this problem is to adjust the relative positions of the tooth crests and the troughs when the gears 12 and 32 are meshed with each other, but the manual work is troublesome and the operator's burden is heavy. .. Automatically causes high cost and is not practical.
In addition, a measure for automatically adjusting the axes Z1 and Z3 is not practical because the factors are many and complicated.

It is an object of the present invention to provide a paper feeding device for a printer, which has a simple structure and is capable of cleaning the locked state of both gears and tooth spills and has a low cost.

[0008]

SUMMARY OF THE INVENTION According to the present invention, it is technically and economically difficult to automatically adjust the relative positions of both gears during meshing or to eliminate a change between both axes. Focusing attention, at least one of the gears is configured to be flexibly deformable with respect to the shaft, thereby achieving the above object.

That is, the present invention is provided with a drive shaft having a drive gear and a feed roller, and a driven shaft having a driven gear and a pinch roller, and by changing the relative positions of both shafts, the drive gear and the driven gear. In a paper feeding device of a printer formed so as to be able to be coupled / separated with each other, a small rigid portion that can be flexibly deformed by a reaction force of a mating gear is provided between at least one of the drive gear and the driven gear and the shaft. It is characterized by

[0010]

In the present invention having such a structure, for example, a small rigidity portion is provided between the drive gear and the drive shaft. Then, even if the tooth crests of the both gears come into contact with each other at the time of meshing, the drive gear bends toward the drive shaft side, that is, the side opposite to the driven gear, so that no lock or tooth spillage occurs. The same applies when the distance between the two axes changes.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. (First Embodiment) In this embodiment, as shown in FIG. 1, a small rigidity portion 20 is provided between the drive gear 12 and the drive shaft 11. The opening of both rollers (15) and (35) is performed by inclining the drive shaft 11 by an angle θ.

In FIG. 1, the small-rigidity portion 20 is composed of a hollow cylindrical portion, that is, a thin-walled portion connecting the drive gear 12 and the boss portion 13 thereof, and is formed integrally with both of them. The material is synthetic resin. This small rigid part 2
0 has a role of flexibly deforming the drive gear 12 in the direction of its own axis Z1 in response to a reaction force (a downward force in FIG. 1) from the driven gear 32 on the other side. Therefore, the drive gear 12
Is configured to form a gap 21 in the drive shaft 11. That is, the entire structure is a cantilever structure with the boss portion 13 as a fulcrum.

In the case of this embodiment, the small-rigidity portion 20 is capable of exerting an action of weakening the return rigidity of the drive gear 12 with respect to the drive shaft 11.

In this embodiment having such a structure, when the drive shaft 11 opened by the angle θ shown in FIG. 1 (axis Z11) is returned to the axis Z1 and the drive gear 12 is meshed with the driven gear 32, both gears are used. If the tooth flanks of 12, 32 contact each other, the reaction force on the driven gear 32 side causes the small rigid portion 20 to bend, and the drive gear escapes in the direction of the axis Z1. Therefore, both axes Z
Even if 1, Z3 are returned to the predetermined intervals, gear lock and tooth spill do not occur.

Moreover, even if the tooth flanks of both gears 12 and 32 are in contact with each other, the small-rigidity portion 20 can be bent in the returning direction. Therefore, if the drive shaft 11 side is slightly rotated, It is possible to smoothly mesh the both 12 and 32.

The same operation is performed when the distance between the axes Z1 and Z3 of both shafts 11 and 31 changes and the tooth crests and roots deeply bite.

According to this embodiment, however, since the small rigidity portion 20 is provided between the drive gear 12 and the drive shaft 11, the tooth flanks of both gears 12 and 32 come into contact with each other or the axis line. Even if the tooth crests and troughs are deeply bitten due to the change in the distance between Z1 and Z3, gear lock and tooth spill can be completely prevented.

Further, since the small rigid portion 20 is formed as a thin portion, it can be formed integrally with the drive gear 12.
It has a simple structure and can be realized at low cost.

Further, since it is not necessary to mount the printer on a frame or the like while finely adjusting the distance between the shafts 11 and 31 to follow the tooth tip shape, the printer can be assembled quickly and easily.

(Second Embodiment) This second embodiment is shown in FIG. In the figure, a pair of left and right small rigid portions 20A and 20B and boss portions 13A and 13B are provided between the drive gear 12 and the drive shaft 11.

Therefore, also in the case of the second embodiment,
In addition to the same operational effects as the case of the first embodiment such as gear lock prevention, the drive gear 12 can be moved in parallel with the axes Z1 and Z3 by the simultaneous bending deformation of both the gears 20A and 20B. The engagement of 32 can be further facilitated.

In each of the above embodiments, the small rigid portion 2
Although 0 is provided on the drive gear 12 side, it may be provided on the driven gear 32 side or on both sides 12 and 32. Further, although the hollow cylindrical shape is integrated, the shape, the number, and the like are not limited to the above disclosed examples.

[0023]

According to the present invention, since a small rigid portion which can be flexibly deformed in response to the reaction force of the mating gear is provided between at least one of the drive gear and the driven gear and the shaft, Even if the gear ridges of both gears come into contact with each other during meshing, or even if the tooth ridges and valleys bite deeply due to changes in the axis of both shafts, gear lock and tooth spillage can be prevented, and the structure is simple. Low cost. Moreover, the whole assembly can be performed quickly and easily.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a second embodiment of the present invention.

FIG. 3 is a side sectional view showing a conventional example.

[Explanation of symbols]

 10 Drive part 11 Drive shaft 12 Drive gear 13, 13A, 13B Boss part 15 Feed roller 20, 20A, 20B Small rigid part 21 Gap 30 Driven part 31 Driven shaft 32 Driven gear 35 Pinch roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masakazu Tanaka 6-78 Minamimachi, Mishima-shi, Shizuoka Tokyo Electric Co., Ltd. Mishima factory (72) Inventor Katsuhiko Kawaguchi 570 Ohito, Ohito-cho, Takata-gun, Shizuoka TEPCO (72) Inventor, Sakae Shiida 570, Ohito, Ohito-cho, Takata-gun, Shizuoka Tokyo Electric Co., Ltd., Ohito factory (72) Inami, Tomomi Iijima 570, Ohito, Ohta-machi, Takata-gun, Tokyo Denki Co., Ltd. (72) Inventor Koei Kimura 570, Ohito, Ohito-cho, Takata-gun, Shizuoka Prefecture Tokyo Electric Co., Ltd. Ohito Factory

Claims (1)

Claim: What is claimed is: 1. A drive shaft having a drive gear and a feed roller, and a driven shaft having a driven gear and a pinch roller. In a paper feeding device for a printer formed so that a driven gear can be coupled / separated, a small-rigidity portion between at least one of the drive gear and the driven gear and the shaft, which can be flexibly deformed by a reaction force of a mating gear. A paper feeding device for a printer, which is provided with.