JPH02243437A - Sheet feed mechanism - Google Patents

Abstract

PURPOSE:To transfer each size of sheets favorably without entailing an skew by regulating a sheet moving direction at both ends of a driven roller, and giving a pressure force to the vicinity of an axial central part. CONSTITUTION:An almost central part in the longitudinal direction of a paper feed upper roller (driven roller) 2 in paired paper feed rollers 1, 2 is set down to a circumferential notch part, thereby exposing a shaft part 2a. A tip hook part 16a of a pressure lever 19 is made contact with a top face of this shaft part 2a, whereby the upper roller 2 regulated in its moving direction at both ends of this hook part is pressed and contacted to a lower roller 1 at all times. Consequently, even when small-sized paper is fed in accord with a one-side reference line A-A or a criterion of paper feeding, pressure distribution is not worsened, thus paper feeding can be done without entailing any skew.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sheet material feeding mechanism that introduces a sheet material between a pair of rollers and conveys the sheet material by rotation of the rollers.

(Prior Art) Such a sheet material feeding mechanism is used, for example, in image forming apparatuses such as copying machines and printers, and other various sheet material handling devices. It has been widely adopted and used as such.

In FIG. 5, reference numeral 1112 denotes a pair of sheet material feeding rerollers, and one roller 1 (lower roller) is a driving roller whose both end shaft portions 1aΦla are rotatably supported by bearings (not shown). Rotational driving force from a drive source mechanism (not shown) is transmitted to the shaft 1a via a drive gear 3 (or sprocket, chain gear, pulley, etc.) fixed to the shaft, and the roller 1 is maintained at a predetermined circumferential speed. to rotate in a predetermined direction. The other roller 2 (upper roller) is a driven roller that is movable in a direction parallel to and in contact with the drive roller 1, and has both end shaft portions 2a, 2a supported by bearings (not shown) to freely rotate. In addition, pressure means (not shown) are applied to both end shaft portions 2a*2a, respectively, to maintain the roller 2 in pressure contact with the roller l with a predetermined pressure. The roller 2 rotates as the drive roller 1 rotates. By introducing the sheet material S into the press-contact nip between the two ends -:) 1 and 2, the sheet material S is gripped between the rollers 1 and 2 and conveyed by the rotational force of the rollers (grip).

BACKGROUND OF THE INVENTION In devices such as copying machines and printers, sheet material conveyance systems are designed either on a so-called one-sided basis or on a so-called central basis.Usually, it is often possible to simplify the apparatus by using a one-sided basis.

(Problems to be Solved by the Invention) By the way, as described above, there is a bridge in which the sheet material grip force is obtained by applying pressure to both ends of the pair of sheet material feeding rollers 1-2 using a pressure means! (Both ends pressurized configuration), the driven roller 2 shown in Fig. 5
As exaggeratedly expressed, the longitudinal center of the driven roller is deflected in the direction G away from the driving roller l due to the influence of the pressing force F-F at both ends, and as a result, the pressure nip between the two ends and the rad 2 is bent. The pressure distribution along the yam (sheet material grip pressure distribution) becomes stronger toward both ends of the pressure nip portion in the yam direction, and becomes a positive distribution that becomes weaker toward the center.

Therefore, when a small-sized sheet material S is introduced and conveyed between the pair of rollers l and 2 with one side reference A, the sheet material S
The grip force received at the pressure nip between roller pairs 1 and 2 is strong toward one side reference conveyance line A in the width direction of the sheet material, and weakens toward the opposite side, resulting in a left-right unbalanced state. The amount of feed of the sheet material on the left and right sides in the width direction of S is also different, which may be a cause of the phenomenon of skewing of the sheet material. Wmax indicates that the maximum number of sheets is being passed.

In addition, even in the case of center-based conveyance, when conveying small-sized sheet materials, the sheet materials are conveyed using the weak gripping force at the longitudinal center of the pressure nip of rollers 1 and 2. In some cases, a phenomenon occurred in which the amount of feed was small relative to the conveyance of the size sheet material.

In either case, it would be a good idea to make the rollers thicker and more rigid, but this is often subject to restrictions due to reasons such as miniaturization of the device itself.

The present invention is also a sheet material feeding mechanism in which a sheet material is introduced between a pair of pressure rollers and conveyed by the rotational force of the rollers, and an object of the present invention is to provide a sheet material feeding mechanism that eliminates the above-mentioned problems.

(Means for Solving the Problems) The present invention provides a roller driven via a drive transmission means;
In a sheet material feeding mechanism, which is configured by rollers disposed in parallel with this and which are pressurized and rotates passively, the sheet material is conveyed by sandwiching the sheet material between the two rollers,
This is a sheet material feeding mechanism characterized by regulating the moving direction at both ends of the driven roller and applying pressure near the center in the axial direction.

Further, in the above, the sheet material feeding mechanism is such that the pair of rollers are connected by a gear and the two rollers are driven together.

(Function) By adopting the central pressure configuration as described above, the deflection of the center part of the roller in the direction of separation and the imbalance in the pressure distribution along the length of the roller-to-nip area caused by this, which occurs in the configuration where pressure is applied at both ends, can be corrected. Therefore, it is possible to stably feed sheet materials of various sizes without causing phenomena such as skew or changes in the amount of conveyance, both in the case of one-sided reference conveyance and in the case of both-side reference conveyance.

Also, by driving both rollers of the roller pair,
It is possible to carry out more stable sheet material feeding.

(Example) This example shows an inkjet printer incorporating a sheet material feeding mechanism according to the present invention.

Figure 1 is a plan view of the sheet material conveyance system, and MS2 is Figure 1 (
FIG. 2 is a cross-sectional view taken along line 2)-(2).

Reference numeral 10 (indicated by a two-dot chain line in FIG. 2) is a paper cassette that is detachable from the paper feed port of the printer, and stores printing paper as a sheet material to be conveyed.

Reference numeral 11 denotes a paper feed roller provided integrally with the support shaft 12. This paper feed roller 11 is a substantially semicircular cutout roller, and is normally stopped and on standby with the cutout facing downward as shown in FIG. It is intermittently driven one rotation clockwise in FIG. 2 by a drive transmission means (for example, a one-rotation clutch).

During one rotation of the paper feed roller 11, the circumferential portion of the roller rotates in contact with the upper surface of the uppermost paper of the stacked sheets in the cassette IO, which causes a feeding force to act on the uppermost paper. In the case of this printer, it is used as a one-side reference conveyance system, in which the top sheet is separated from the next and lower stacked sheets and fed into the printer main body by working together with a separating claw member, etc. The line A-A in FIG. 1 is the one-sided reference conveyance line.

The separated and fed sheets pass between the lower guide plate 13 and the upper guide plate 14 and are introduced into the nip between the lower paper feed roller l and the upper roller 2. The lower roller 1 is driven to rotate counterclockwise, and the upper roller 2 is rotated in pressure contact with the lower roller 1, and the paper introduced into the nip between the rollers 1-2 is It is caught between the rollers 1 and 2 and is relayed.

Immediately after the leading edge of the paper is bitten by the rollers 1 and 2, the contact passage of the circumferential part of the paper feed roller 11 with the paper ends, and the paper feeding action by the paper feed roller 11 ceases, and the paper is fed. When the roller 11 completes one rotation, its rotation is stopped and the roller 11 returns to its initial standby and stopped state with the cutout facing downward as shown in FIG.

Even if the paper feeding action by the paper feed roller 11 ceases, the leading edge of the paper is already caught between the paper feed upper and lower rollers 1112, so the paper continues to be conveyed by the rotation of these rollers, and the paper is moved to the platen guide. 19 and is introduced into the nip between the lower paper discharge roller 24 and the upper roller 25. The lower paper ejection roller 24 is rotated counterclockwise in conjunction with the rotation of the lower paper feed roller 1 at a predetermined circumferential speed greater than the lower roller 1 for transporting one sheet, and the upper roller 25 is driven to rotate at a predetermined circumferential speed higher than the lower roller 1 for transporting one sheet. It is in pressure contact with the roller 24 and rotates as a result.

When the leading edge of the paper gets caught in the nip between the upper and lower paper ejection rollers 24 and 25, the rotation speed of the paper ejection roller pair 24 and 25 is higher than that of the paper feed roller pair l and 2, so the second paper A tension seal acts on the portion of the paper between the pair of feed/rerollers 1 and 2 and the pair of discharge rollers 24 and 25, that is, the portion of the paper on the upper surface side of the platen guide 19, so that the sheet is kept in a taut, flat state without wrinkles or slack. Become. Therefore, the leading edge of the paper is connected to the paper ejection roller pair 2.
When the above-mentioned paper portion is caught between 4 and 25 and becomes a taut and flat state, the lower paper feed roller 1 and the lower paper discharge roller 2
4 is temporarily stopped.

The above paper portion remains in a taut, flat state.

Then, a well-known inkjet head 20 (shown by two-dot chain line in FIG. 2) is applied to the upper surface of the portion of the paper that is in a tension plane state on the upper surface side of the platen guide 19 and has stopped being conveyed.
performs a scanning operation and print processing is executed on the partial surface of the paper. Thereafter, the paper is fed in an intermittent fixed amount by controlling the rotational drive and stop of the lower paper feed roller 111 and the lower discharge roller 24 every time one scan operation of the head 20 is completed.

The print scanning operation is repeated.

The lower paper feed roller 1 and the upper roller 2 are rotatably supported at their shaft ends between the left and right side plates 31-32 of the printer via bearings 18, 18, respectively.

FIG. 3 shows a front view of the bearing 18, which has a round bearing hole 18a on the lower side and an elongated bearing hole tab above the bearing hole 18a having a long axis in the vertical direction.

The 1 m shaft end of the paper feed lower roller l is inserted into the lower round bearing hole 18a.
The shaft end ga of the paper feed upper roller 2 is fitted into the upper elongated bearing hole 18b and is supported, so that the paper feed upper roller 2 is moved in the direction of the paper feed lower roller l. It can move freely within the long hole range of the bearing hole 18b.

In this embodiment, a substantially central portion in the longitudinal direction of the upper paper feed roller 2 is cut out in the circumferential direction to expose the shaft portion 2a, and the tip of the pressure lever 16 is hooked onto the upper surface of the shaft portion 2a. @18a is brought into contact with the paper feed upper roller 2 to keep it in constant pressure contact with the paper feed lower roller l.

The pressure lever 16 is connected to the first cut-out piece 14 of the upper guide plate 14.
Support freely swinging around a pin shaft 15 implanted in a,
A tension spring 17 connects the free end of the arm opposite to the arm on the lea side of the tip end hook portion of the lever 16 and the upper end of the second cut-out piece 14b of the upper guide plate 14. The lever 16 is constantly urged to rotate in the counterclockwise direction in FIG. 2 about the pin shaft 15 by a spring 17, and its rotational urging force applies a pressing force of the upper paper feed roller 2 to the lower paper feed roller 1.

In this embodiment, an SOS roller whose surface has been subjected to a sheet blasting process is used as the paper feed lower roller 1.

Although a CR rubber roller is used as the paper feed upper roller 2, it is not limited to this.

The upper and lower guide plates 14-15 and the platen guide plate 19 are fixedly attached between the left and right side plates 31 and 32.

The lower sheet discharge roller 24 is rotatably supported at both ends of its shaft portion 24a between the left and right side plates 31 and 32 via bearings 23 and 23, respectively. The upper paper ejection roller 25 has its shaft portion 2
Attach both ends of the pin shaft 2 to the left and right side plates 31 and 32, respectively.
A pair of left and right swing levers 27, 27, which are provided to swing freely around 6-26, are rotatably supported between the tips of the levers 27, 27, and the arms on the opposite side of the levers 27-27 and the left and right side plates. The cut-and-raised spring hooks provided at parts 31 and 32 are located at parts 31a and 32.
A is maintained in a state of pressing contact with the upper surface of the lower paper ejection roller 24 by connecting it with a tension spring 28-28.

In this embodiment, the lower paper discharge roller 24 is made of SO with good surface properties.
The S roller is used, and resin is used as the paper discharge upper roller 25, so that slipping occurs when a certain amount of tension is applied to one paper, but the present invention is not limited to this.

A drive gear 3 is attached to one end of the shaft 1a of the lower paper feed roller 1.
A drive gear 22 is also fixed to one end of the shaft 24a of the lower paper discharge roller 24, and both gears 3-22 are connected by an idler gear 21 pivotally mounted on the side plate 31. The gear 3 of the lower roller l receives a rotational force from a drive gear of a drive source mechanism (not shown) to rotate the paper feed lower roller 1, and in conjunction with this, the gear 3 also transfers to the gear 22 via the idler gear 21. The drive is transmitted and the lower paper discharge roller 24 is rotationally driven. In this case, the ratio of the gears 3-21-22 is set so that the peripheral speed of rotation of the lower paper discharge roller 24 is higher than that of the lower paper feed roller l by a predetermined value.

In this embodiment, in accordance with the present invention, the paper feed roller pair 1-2 is pressed into contact with the lower roller 1 by applying a pressing force to the upper roller 2, which is the driven side, near the center in the axial direction. It was confirmed that even when the one-side reference A-A shown in the first figure was adopted as the reference line and small-sized paper was fed in line with the reference line, the pressure distribution did not deteriorate that much and it was possible to feed the paper without causing any practical problems. . It goes without saying that good paper feeding can be achieved in the case of paper with the maximum paper stack Wmax. Even when the center reference was adopted, good results were obtained because the deflection G at the center of the roller as shown in FIG.

Embodiment 2 (FIG. 4) In this embodiment, in the apparatus of Embodiment 1 described above, the shaft end 1 of the paper feed lower roller l on the opposite side to the side where the drive gear 3 is attached is used.
a, and a gear 42 is also fixed to the shaft end 2a of the upper paper feed roller 2 on the same side, and both gears 41
- The rotational driving force of the lower paper feed roller 1 is transmitted to the upper paper feed roller 2 via the gears 41 and 42, and the roller 2 also rotates actively. In this case, the gear ratios of the gears 41 and 42 are set so that the circumferential speeds of the upper and lower rollers 1 and 2 are the same.

According to this embodiment, since the paper feed upper roller 2 also has a driving force, a more stable paper feeding state can be expected.

(Effects of the Invention) As described above, it is composed of a roller driven via a drive transmission means, and a roller disposed parallel to the roller and pressurized and driven to rotate.

Regarding the sheet material feeding mechanism that transports the sheet material by sandwiching it between both rollers, the moving direction is regulated at both ends of the roller on the pressure side, and the pressure is applied at the center of the roller, so that sheets of various sizes can be conveyed. It has become possible to realize good sheet material feeding without skewing the material.

Further, by further connecting the pair of rollers described above with a gear so that the two rollers are driven together, it is possible to carry out more stable feeding of the sheet material.

[Brief Description of the Drawings] Fig. 1 is a plan view of a sheet material conveyance system of an inkjet printer incorporating a sheet material (print paper) feeding mechanism according to the present invention, and Fig. 2 is a plan view of (2)-( 2) A cross-sectional view along the line, Figure 3 is a front view of the bearings of the pair of paper feed rollers, and Figure 4 shows the upper and lower paper feed a-ra shafts coupled with gears to give the upper roller a driving force. FIG. 5, which is a front view of the example roller pair, is a schematic diagram illustrating the occurrence of deflection of the upper roller in the both-end pressure type and the problems caused by it. 1 is the lower paper feed roller, and 2 is the upper paper feed roller. 14a, 14b, 15, and 16 are upper roller center pressing mechanisms, and 18 is a bearing for the upper and lower rollers 1 and 2. Illustration of a spear

Claims (2)

[Claims] (1) Consisting of a roller driven via a drive transmission means, and a roller disposed parallel to the roller that is pressurized and rotates drivenly, and a sheet material is sandwiched between the two rollers. A sheet material feeding mechanism for conveying a sheet material, characterized in that the moving direction is regulated at both ends of a driven roller, and a pressing force is applied near the central portion in the axial direction. (2) The sheet material feeding mechanism according to claim 1, wherein the pair of rollers are connected by a gear and the two rollers are driven together.