JPH0710350Y2 - Original cover device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a document cover device which is provided so as to be openable and closable with respect to a mounting table in order to bring a document into close contact with the mounting table.

<Prior Art> An image forming apparatus optically scans an original placed on an original placing table composed of a transparent member, and forms an optical image at this time on a uniformly charged image carrier. As a result, an electrostatic latent image corresponding to the image of the original is formed on the photoconductor. This latent image is then visualized as a toner image by the developing device, the toner image is appropriately transferred onto the conveyed paper, and the paper is discharged to the outside of the image forming apparatus via the fixing means. As a means for optically scanning the original document,
The mounting table itself on which the original is placed is moved with respect to the optical system for forming an image on the image carrier, or a part of the optical system is made parallel to the mounting table fixed at a fixed position. The former optical scanning means is called a document table moving method, and the latter is called an optical moving method. The document table moving method has an advantage that the image forming apparatus can be downsized by eliminating the need for a space for moving a part of the optical system in the image forming apparatus unlike the optical moving method.

Further, the document cover device for bringing the document into close contact with the document placing table is provided so as to be openable and closable with respect to the document placing table by a supporting portion provided at an edge of the document placing table, and is provided on the side facing the document. The surface is white. In particular, the original cover device prevents external light from entering the inside of the apparatus and prevents light from an exposure lamp for illuminating the original surface to leak outward when copying is performed. Further, the document cover contributes to removing unnecessary electric charge of the image carrier on the white surface, and also serves to press the document against the document mounting table.

Here, when the document cover device is closed and the document is pressed against the document placing table, if the document cover device shifts to the left and right, the placement position of the document may also shift. If this is the original scanning operation,
The optical image to be formed on the image carrier is distorted and a clear electrostatic latent image is not formed. This phenomenon becomes remarkable especially in the scanning method of moving the document table. That is, the scanning movement of the document placing table causes the holding portion of the document cover device to swing to the left and right, and the document is displaced in accordance with the shake of the document cover device, which affects the image and the position of the image formed on the transfer sheet. Will be shifted.

One end of the document cover device is rotatably supported by the document table so as to be openable and closable. Conventionally, the original cover and the original cover supporting portion are designed to allow the original cover to be freely opened and closed even when a dimensional change occurs in consideration of the error of the mold at the time of molding and the dimensional change due to heat shrinkage, warpage, etc. In order to make it, I had a play of about 1 millimeter. Therefore, as described above, even if the document is pressed, there is a problem that the document cover device is loosened and the document is displaced due to the swing during scanning of the document. Therefore, a nylon washer or the like is inserted in the play (clearance) of the shaft support portion between the document cover part and the cover holding part of the document cover device according to the size of the play to reduce rattling as much as possible. A spring or the like was used as the document pressing means to strengthen the pressing force for pressing the document to prevent backlash, but in any case, the cost was high and the efficiency of the assembling work was poor.

<Purpose> In view of the above problems, the present invention provides a document cover device capable of accurately fixing a document without swinging the document cover device during exposure scanning of a copying machine or the like.

<Embodiment> FIGS. 1 and 2 are overall views of an image forming apparatus including a document cover device according to the present invention. A document cover device for pressing a document is provided on an upper surface of an image forming device main body 1. ing. FIG. 1 shows a state in which the document cover is closed, and FIG. 2 shows a state in which the document cover is opened. FIG. 3 is an explanatory view of the method for assembling the document pressing cover, and FIG. 4 is a diagram showing the configuration of the document cover device. 5 and 6 are sectional views of the main part of the document cover. Detailed description will be given below with reference to the drawings.

First, in FIG. 1 and FIG. 2, a transparent original placing table 3 is arranged on the upper part of the copying machine main body 1. The document placing table 3 is provided with a document placing reference end 30 for aligning the leading ends of the placed copy documents. A document cover holding portion 4 that constitutes the document cover device 2 is provided on one edge of the document placing table 3. The document cover holding section 4 is attached to the moving document placing table side in the case of the document table moving method, and is attached to the copying machine main body side in the case of the optical system moving method. One end of the document cover 5 is pivotally supported by the document cover holding portion 4, and therefore the document cover 5
Is rotatable with respect to the document cover holding portion 4.
A pressing mat 6 having a flexible white member (so-called white mat) attached to the surface of a foamed elastic body is attached to the original pressing surface side of the original cover 5.

Next, the detailed structure of the document cover device 2 will be described with reference to FIG. A convex portion 51 formed in a convex shape is integrally formed at one end of the document cover 5. A support shaft 7 for opening and closing the document cover 5 is provided on both end faces of the convex portion 51.
The a and 7b are provided so as to be coaxially separated by a distance H. Here, the distance H is the width of the convex portion 51 between the end faces provided with the support shafts 7a and 7b. Also, in the vicinity of the support shaft 7a side,
A locking portion 8 is provided on the document cover 5 side with a small distance K therebetween. This minute distance K is the distance between the end surface of the convex portion 51 provided with the support shaft 7a and the surface of the locking portion 8 facing this end surface.

In contrast to the original cover 5, the cover holder 4 has a convex portion.
A recess 41 corresponding to 51 is integrally formed. Bearings 9a and 9b, which are fitted to the support shafts 7a and 7b at a distance I, are provided on the end surfaces 41a and 41b of the recess 41, respectively. Here, the distance I is the width of the recess 41 between the end faces 41a, 41b provided with the bearings 9a, 9b. A locking portion 10 is provided in the vicinity of the bearing 9a side with a small distance J therebetween. The small distance J is
This is the distance between the end surface 41a of the recess 41 and the outer surface of the locking portion 10. The locking portions 8 and 10 are provided so as to face each other so as to come into contact with each other on the F surface orthogonal to the supporting shafts 7a and 7b direction of the document cover 5 in FIG.

When assembling this document cover device, first, the wide surfaces of the document cover 5 and the cover holding portion 4 are removed as shown in FIG. 3B.
It is held at an angle of 90 degrees so that the locking portions 8 and 10 are out of the facing angle. Next, the original cover 5 is bent, and the length including the distance H which is the width of the convex portion 51 and the support shafts 7a and 7b is shorter than the distance I which is the width of the concave portion 41 of the original cover holding portion 4. The support shafts 7a and 7b are fitted in such that the center axes of the bearings 9a and 9b are aligned with each other, and the original cover 5 is released from the bending to be fitted.

When a document is pressed by using the document cover device 2 assembled as described above, the clearance between the document cover 5 and the cover holding portion 4 is the document placement reference position 30 as shown in FIGS. 4A and 4B. Thirdly, it becomes unevenly distributed on the opposite side of
This will be described with reference to FIGS. 5, 5 and 6.

FIG. 5 is a detailed description of the shaft support portion of FIG.
FIG. 6 is a sectional view, and FIG. 6 shows the supporting shaft 7a and the locking portions 8 and 10 in FIG.
FIG. 7 is a cross-sectional view taken along the line AA ′ for explaining the positional relationship of A in more detail.

Distance for fitting the support shafts 7a, 7b to the bearings 9a, 9b (H ±
h) and the distance (I ± i) are such that (I ± i)> (H ± h) h: H so that the document cover 5 is always rotatable with respect to the cover holding portion 4 in a normal use state. Dimensional tolerance i: It is designed to meet the dimensional tolerance of I.

Therefore, even if (I−i) = (H + h) is set to minimize backlash, the maximum allowable error is 2 (h + i).

In the present invention, the document cover is bent and assembled by using the above-described long-distance fitting with the distances H and I, and the locking is performed by a minute distance. That is, the support shaft 7a has a locking portion for a minute distance. Similar to the above, the original cover 5 and the cover holder 4 are designed to be always rotatable (K ± k)> (J ± j) k: K dimensional tolerance j: J dimensional tolerance. It When the backlash is the minimum, (K−k) = (J + j) The maximum allowable error is 2 (j + k).

As is clear from FIG. 3, I> H >>K> J, and the tolerance of the fitting dimension between the document cover 5 and the cover holding section 4 is determined by the locking dimension due to the minute distance between the locking sections 8 and 10. The maximum dimensional tolerance is sufficiently shortened by restricting the maximum size.

Actual design example Distance H = 380 + 0 (-0.6) Distance I = 380-0 (+0.6) Minute distance K = 4 + 0 (-0.1) Minute distance J = 4-0 (+0.1) That is, according to the present invention The maximum permissible error has been reduced by a factor of 6 from 1.2 mm to 0.2 mm.

Furthermore, since this minute distance locking portion is arranged on the side of the original placement reference end 30, the edge portion of the white mat is the original placement reference end 30.
The originals can be overlaid on each other with almost no error, light leakage does not occur at the leading edge of the original, and black lines are not formed on the leading edge of the copy paper.

According to the present invention, the support shafts 7a and 7b are provided on the document cover 2 side, and the bearings 9a and 9b are provided on the document cover holding portion 4 side, but they can be provided in the opposite way.

<Effect> According to the manuscript cover device of the present invention, one end of the manuscript cover is rotatably supported with respect to the cover holding portion, and the rotating shaft is rotatably supported at a plurality of positions. Since the locking member for restricting the relative movement of the document cover and the cover holding portion in the axial direction is provided in the range shorter than the distance between the shaft supporting portions, that is, the document cover 5 and the cover holding portion 4
By limiting the tolerance of the mating dimension with and by the locking dimension due to the minute distance of the locking parts 8 and 10, the maximum dimension tolerance is sufficiently shortened, and the original cover is almost rattled in the cover holding part. It can be held stably without causing it. Therefore, even when the original is exposed and scanned, the original cover does not swing, and the original can be accurately fixed, and reading failure can be prevented.

Further, since the locking member is provided on the document placing reference end side of the document placing table, the leading end of the document can be reliably pressed against the document placing reference portion.

[Brief description of drawings]

1 and 2 are external views of an image forming apparatus provided with a document cover device according to the present invention. FIG. 1 shows a state in which the document cover is closed, and FIG. 2 shows a state in which the document cover is opened. It is a figure. FIG. 3 is an explanatory view of an assembled state of the document pressing cover, FIG. 3A is a plan view, FIG. 3B is a side view, and FIG. 4 is a diagram showing a configuration of a document cover device.
4A is a plan view, FIG. 4B is a side view, FIG. 5 and FIG.
Each drawing is a cross-sectional view of the main part of the document cover. 1: Copier main body, 2: Document cover device 4: Document cover holding part, 41: Recessed part 5: Document cover, 51: Convex part 7a, 7b: Support shaft, 9a, 9b: Bearing 8, 10: Locking part

Claims (1)

[Scope of utility model registration request] 1. A document, which is rotatably provided on a document cover holding portion provided at one side edge of a document placing table on which a document of the image forming apparatus is placed, for pushing the document on the document placing table. In a manuscript cover device including a cover, a support shaft (7a, 7b) provided on a manuscript cover (5) or a manuscript cover holding part (4) is provided with a bearing ( 9a, 9b), and a locking member (8, 10) that locks with each other and that holds a clearance smaller than the clearance between the support shaft and the bearing in the axial direction, on the document mounting reference end side of the document mounting table. An original cover device, which is provided so as to face the original cover and the original cover holder.