JPS6236245A - Sheet material feeder - Google Patents

Abstract

PURPOSE:To prevent skew by transporting sheet material with different widths with their one side used as reference by the use of a transport roller with a width a little smaller than the max. sheet width, and by installing a friction hindering member in the middle part downstream said roller for the purpose of prevention of double feed. CONSTITUTION:When resist rollers 16, 17 began rotating, a frictional rotor of a friction hindering member 3 is driven by a one-way clutch which provides free motion for sheet feeding direction, and only the portion corresponding to the friction load is applied. In case B5 sheets of 182mm wide are to be fed with their reference edges A aligned, the dislocations of said friction hindering member 3 has a with respect to the sheet and resist rollers 16, 17 will be (102 mm-80mm)/102mm and (108mm-95mm)/108mm, respectively, both lying within 30%. The spring on the non-reference side of rollers 16, 17 is, on the other hand, strengthened in an amount corresponding to deflection, and thus skew is eliminated. In the case of A4 sheets of 29mm wide, the friction hindering member 3 is in the center of the transport width approximately despite a deviation from the sheet center, and thus no skew will be generated.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a sheet-like material feeding device in an image forming apparatus, and more specifically, the present invention relates to a sheet-like material feeding device in an image forming apparatus, and more specifically, the present invention relates to a sheet-like material feeding device that prevents double feeding of sheet-like materials by the frictional force of a friction member. The present invention relates to a sheet-like material feeding device of this type.

<Prior art> Conventionally, a sheet material feeding device, as shown in FIG.
It has a friction rotating body (feeding roller) 2 that is rotationally driven around a shaft l, and a friction prevention member (friction butt) 3 made of a material with a high friction coefficient such as rubber or synthetic resin. It is fixed to one end of a separation member 5 that is pivotally supported by a support shaft 5a, and is pressed against the friction rotary body 2 at a predetermined pressure by a splint 6 adjusted to the other end of the separation member 5. Further, a sheet-like material storage stand 7 is arranged facing the friction rotating body 2, and the free end of the holding stand 7 is urged by a spring 9 toward the rotating body 2, and the upper surface of the free end is biased toward the rotating body 2. A friction butt 10 is also fixed thereto.

The uppermost sheet-like material 11 such as a large number of papers stacked on the storage table 7 is in contact with the friction rotating body 2, and the uppermost sheet-like material lIU When two or more sheet-like materials 11 are fed by the frictional force based on the rotation in the direction, the lower sheet-like material is separated by regulating its feeding by the pressure contact of the friction pad 3, and the sheet-like material 11 prevents double feeding in which two or more sheets are fed.

<Problems to be Solved by the Invention> Conventionally, sheet-like materials were loaded using a cassette so that the center of the sheet-like material was located at the center of feeding, regardless of the difference in size. With the miniaturization of copying machines and the diversification of sheet-like material sizes, devices have been devised for mounting sheet-like materials with one edge thereof as a reference. In the case of this device, as shown in FIG. 6(A), it is necessary to arrange the friction rotating body 2 within the radius area of the sheet-like material 11s of the minimum size, but the arrangement of the friction rotating body 2 is limited to the maximum size. With respect to the dimensions of the sheet-like material 11, the position will be significantly shifted from the center of the radius.
), the position of the rotating body 2 is shifted in the lateral direction with respect to the sheet-like material 11s of the smallest size to an extent that skewing does not occur, and the sheet-like material 11M of the largest size is prevented from skewing. Also, if the difference between the maximum dimension and the minimum dimension is small, for example, the minimum dimension A5 (210 mm) and the maximum dimension A4 (29
Although it is possible to accommodate a difference in size up to about 7 mm), it is not possible to accommodate a larger difference in size, resulting in skewing.

This is because the length distribution of the roller surface portion of the feed roller pair 12.13 located downstream in the sheet feeding direction that comes into contact with and feeds the sheet-like material is the maximum size of the sheet as shown in Figure 6 CB). This is due to the fact that they are provided according to the length of the 11 sentences.

That is, the pair of feeding rollers 12 and 13 are pressed against each other by springs 14 at both ends thereof, and the surface of the roller 13 is coated with rubber 13a having a high friction coefficient on the metal core part 13b, and the other roller 12 is made of metal. However, as described above, since pressure is applied at both ends of the roller pair 12 and 13, the clamping force is high at the roller ends and low at the center due to deflection. Therefore, when conveying narrow sheets.

Since the reference end of the sheet is held at the roller end and the other end is held at the center of the rollers, a difference occurs in the conveying force, and furthermore, a blocking member 3 is provided at the rear end of the sheet, which adds a load to conveyance. This causes skew (the non-reference side lags).

In addition, when conveying a wide sheet-like material, the rollers are located at both ends of the sheet with a high clamping force, but since the blocking member is provided offset from the center of the sheet to the reference edge, A biased conveyance load is generated in the conveyance of the roller pair 12.degree. 13, which also causes skew (skew where the reference side lags behind).

<Object of the Invention> The present invention has been made in view of the drawbacks of the above-mentioned conventional examples, and in order to feed sheet materials stacked one by one with one edge as a reference, the sheet materials are biased toward the reference from the center of the sheet materials. A sheet-like material feeding apparatus having a friction-preventing member provided with a sheet-like material feeding device that prevents skewing from occurring due to the load of the friction-preventing member when the sheet-like material is conveyed by a conveying roller located on the downstream side. The purpose is to provide a transmission device.

Means for Solving the Problems> In order to achieve the above object, the feeding device according to the present invention disposes a conveyance roller downstream of the friction prevention member, and the contact portion of the conveyance roller with the sheet, that is, The sheet member is characterized in that the lengths of the reference side and the non-reference side of the sheet member are arranged to be approximately equal in length with respect to the position of the friction prevention member.

Based on the above-mentioned means, when feeding small-sized sheet materials, the end of the conveying mountain on the non-reference side of the roller is closer to the center of the roller than in the conventional example shown in Fig. 6. The deflection is reduced, and the difference in clamping force between both ends and the center of the roller is reduced, making it possible to suppress the occurrence of skew.

Next, in the case of feeding a large-sized sheet-like material, the occurrence of opening can be similarly suppressed since the transport load is present near the center of the transport width.

<Embodiment> Hereinafter, an embodiment in which the present invention is applied to a feeding device of a copying machine will be described along with the drawings.

First, an embodiment will be described with reference to FIGS. 1 and 2, in which the present invention is applied to a register roller that serves as a conveying roller and takes timing between an image on a drum and a sheet.

In FIG. 1, E is the sheet material feeding device described above;
Below the photosensitive drum 15 are register rollers 16 and 17 for synchronizing the image on the photosensitive drum 15 and the sheet.
is installed. As shown in FIG. 1, the register roller 17 has a neoprene rubber layer 17 on the surface of the iron core 17b.
It has a. The register roller 16 is made of iron and has a roller shape, and is pressed against the register roller 17 by springs 21 and 22 at both ends thereof, as shown in FIG. Here, the length of the rubber surface layer is being conveyed. A sensor 20 is provided upstream of the register rollers 16 and 17 to detect the passage of the leading edge of the conveyed sheet.

Sea) 11 is a guide plate 18.
19, and is fed into the nip between the register rollers 16 and 17, which have stopped rotating.

The friction rotor 2 is stopped after a certain period of time by the signal from the sensor 20 and a timer (not shown). At this time, the sheet forms a loop between the guide plates 18 and 19 and stops.

Next, the register roller pair 16, 17 starts rotating at a timing synchronized with the image on the drum 15. At this time, a one-way clutch (one-way clutch) that is free only in the sheet feeding direction is installed between the friction rotary body 2 and its drive shaft l.
(not shown) is provided. Due to this action, the friction load generated by the sheet and the friction prevention member 3 acts on the register rollers 18, 17. Here, the small-sized sheet material is B5 (width in the conveying direction 182 mm).
) and a large-sized sheet-like material A4 (width in the conveyance direction: 2971 layers), the positional relationship between the double-feed prevention section, the register roller during conveyance, and the sheet is as shown in FIG. The dashed line indicates that the conventional register roller is being conveyed.

(1) The double feed prevention section for B5 size sheets is 82■■
: 60mm and almost in the center.

(2) The width of the register roller should be 9 degrees relative to the center of the double feed prevention part.
5m ■: 108mm and almost in the center.

(3) The pressure contact force at both ends of the register roller is set to be almost the same on the reference side and the non-reference side by increasing the spring force by the amount that is lower on the non-reference side due to deflection.

(0 substantially the same is determined by experiment.

is within 30%. For example, these are both within 30%. However, it goes without saying that it is not limited to within 30% depending on the difference in required precision.

With the above arrangement, the position of the double-feed prevention part, which causes a frictional load on B5 size sheets, is approximately at the center, and the non-reference side conveying end of the registration roller is 80 mm compared to conventional registration rollers, which is B5 size. Since the non-reference end of the sheet is approached, the conveyance force at this portion approaches the conveyance force at the reference end.

The position of the double-feed prevention part for the B4 size sheet is shifted from the center toward the reference side, but it is located approximately at the center with respect to the register roller width during actual sheet conveyance.

As described above, skew can be eliminated for both small and large sizes.

In such a configuration, it goes without saying that the pressure balance on the non-reference side of a small-sized sheet can be further improved by increasing the rigidity of each register roller to reduce its individual deflection.

FIG. 6 shows a conveyance roller according to another embodiment of the present invention. The surface of the conveyance roller is distributed as narrow rollers, and in this type as well, the distribution of the conveyance rollers on the reference side and the distribution of the rollers on the non-reference side is approximately the same with respect to the position of the double-feed prevention member. A similar effect can be obtained by doing so.

As described above, the conveying roller is distributed so that the load generated by the double-feed prevention mechanism is located approximately at the center downstream of the load, and the pressure contact force at the reference side end and non-reference side end is set to be the same. The skew can be reduced or eliminated by this simple method.

<Effects of the Invention> Since the sheet material feeding device according to the present invention has the above-described configuration, it has the effect of preventing the sheet material from being skewed.

[Brief explanation of drawings]

FIG. 1 is a front view showing a schematic configuration of a sheet material feeding device according to the present invention, FIG. 2 is a perspective view, FIG. 3 is a plan view, and FIG. 4 is a perspective view of another embodiment. FIG. 5 is a front view showing the general configuration of a feeding device equipped with a friction prevention member, FIG. 6(A) is a plan view of a conventional example of a sheet material feeding device,
FIG. 6(B) is a side view. 2-m-Friction rotary body 3-11 Friction barrier member 16.17--- Feeding roller pair

Claims (2)

[Claims] (1) In a feeding device having a friction prevention member provided offset from the center of the sheet-like material toward the reference side in order to feed the sheet-like materials stacked one by one with one edge side as a reference, the friction A pair of conveying rollers that convey the sheet-like material and are in pressure contact with each other is provided downstream of the blocking member, and the contact portion of the pair of conveying rollers with the sheet-like material is on the reference side and 1. A sheet material feeding device characterized in that non-reference sides are configured to have substantially the same length. (2) The pressure contact force on the reference side and the non-reference side of the transport roller pair is set to be substantially the same.
The sheet material feeding device according to item 1).