GB2326044A

GB2326044A - Window assembly for optical scanner

Info

Publication number: GB2326044A
Application number: GB9711652A
Authority: GB
Inventors: Henry Peng; Hocking Chen; Ming-Tsan Lin
Original assignee: Umax Data System Inc
Current assignee: Veutron Corp
Priority date: 1997-06-04
Filing date: 1997-06-05
Publication date: 1998-12-09
Also published as: AU686982B3; GB9711652D0

Abstract

A window assembly comprises lower plates 22, each with a stepped portion for supporting a transparent window, and upper plates 21 which are secured to the lower plates so as to clamp the window. The plates are preferably secured by screws which may be adjusted during maintenance, if required, to correct the flatness of the window. This is an advantage over prior art, glued, arrangements. A further plate 215 may be provided to extend between the upper and lower plates and to have an end stop 2151 to restrain the top edge of the window.

Description

WINDOW ASSEMBLY MECHANISM FOR AN OPTICAL SCANNER The invention relates to a window assembly mechanism for an optical scanner, and more particularly to a window assembly mechanism without any glue-in connection.

Gluing connection between the transparent window and the frame of an optical scanner has been long known in the art. As shown in FIG. 1, a cross section view of an optical scanner, the window assembly 1 comprises a transparent window 11 and a frame 12, located right on top of the housing 3 of the optical scanner. In the housing 3 of the scanner, it allows imaging components (not shown in the drawing) inside the housing 3 to screen the original document (not shown in the drawing and always placed on top of the window assembly 1) through the transparent window 11. The frame 12 acts as a carrier and protection to the transparent window 11. Glue 13 is applied between the frame 12 and the transparent window 11 to hold both parts together.

It is an obvious object for an optical scanner to faithfully rebuild the color, size, and position of all in the original document. To achieve such a fidelity satisfactorily, maintaining the transparent window 11 at a horizontal flat surface is crucial. If the horizontal surface can not be sustained, it is quite possible that the imaging will be blurred and result in an unsatisfied result. On the other hand, it simply implies that the reliability and the accuracy of the optical scanner is no longer remained.

Various factors have been known in the art to affect the horizontal surface flatness of the transparent window 11; such as the manufacture tolerance, assembly distortion, unevenness in gluing, and so on. Among those factors, the manufacture tolerance and assembly distortion are instinctive essentially in manufacturing, and can't be improved except utilizing even advanced manufacturing technique. However, such a upgrading resort in improving the manufacturing also implies that the cost will be increased and, perhaps, the product's competitiveness will lose.

Moreover, the glue 13 applied between the frame 12 and the transparent window 11 obviously make worse the horizontal surface flatness of the transparent window 11, and thus plays a negative factor to the accuracy of the scanner. As illustrated in FIG.1, the glue 13, after its solidification, occupies a small volume. Though the dimension of the glue 13 is hardly noticeable by compared with those of other components in the scanner, yet it is remarkable enough to the wave length of light the scanner utilizes. Also, it is presumed apparent that the gluing is uneven, and the unevenness degrades the performance of the scanning for sure.

In addition, it is well known in the art that the constraint force field around the glued transparent window 11 is a non-distributed force field, which will induce stress creep either by crack growing, or by a plastic deforming. In case of the solid glue to be brittle, the non-distributed constraint force field will release its unbalancing (bending moment) through the dislocation of the glue. On the other hand, in case that the solid glue is plastic, the non-distributed constraint force field will release the instability through deforming the glue. Apparently, if either one to be true, the imaging accuracy will prevail further into the sad side under the circumstance that the manufacturing tolerance and assembly distortion have been already there.

Particularly, if gluing is applied to an optical scanner with an original document moving mechanism, aforesaid problem will have no chance to be corrected; due to the fact that the dynamics system, formulated by the moving window assembly and all other parts involved in the sliding motion of the window assembly, will keep contributing a cyclically back-and-forth motion upon the scanner structure. In such a situation, accurate imaging by the scanner is unfeasible and no more expected.

Accordingly, it is a primary object of the present invention to provide a window assembly mechanism for an optical scanner, which has a better mechanical strength to maintain the surface flatness of the window assembly and to reduce its influence on the imaging accuracy.

The present invention, which is constructed by a plurality of metal plates to hold securely a transparent window in between, comprises a lower structure for carrying the transparent window and an upper structure fixed to the lower structure to assure the holding of the transparent window.

The lower structure according to the present invention further comprises a left-side plate and a right-side plate, positioned parallel to restrain the transparent window at both sides.

The upper structure in accordance with the present invention further comprises a first plate, a second plate, and a third plate to jig the transparent window to the lower structure on top at its right side, left side, and top edge, respectively.

The third plate further includes an edge stop as a restraint wall to the top edge of the transparent window, and step-shape ends to go with the counter step-shape ends of the first and the second plates.

It is another object of the present invention to provide a window assembly mechanism to an optical scanner, who has better stiffness to sustain the surface flatness under the inherent constraint force and any unexpected external loading.

It is a further object of the present invention to provide a compact window assembly mechanism for an optical scanner, which roots out problems of unevenness and stress creep in conventional gluing window assembly.

Yet another object of the present invention is to provide an adjustable window assembly mechanism, which can be calibrated for a maintenance purpose to take into account the accumulating tolerance and unexpected distortion during operation.

All these objects are achieved by the window assembly mechanism for an optical scanner described below.

The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which FIG. 1 is an elevational section view of the housing and the window assembly of an optical scanner with a conventional glued window assembly.

FIG.2 is a perspective view of the embodiment of the window assembly mechanism for an optical scanner in accordance with the present invention.

FIG.3 illustrates a perspective and exploded view of the embodiment of the window assembly mechanism for an optical scanner in accordance with the present invention.

The invention disclosed herein is directed to a window assembly mechanism for an optical scanner. In the following description, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by one skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. In other instance, well-known components are not described in detail in order not to unnecessarily obscure the present invention.

Shown in FIG.2 is a window assembly mechanism 20 for an optical scanner constructed in accordance with the present invention. The window assembly mechanism 20 is constructed by a plurality of substantial plates to hold securely a transparent window 11 in the middle of the window assembly mechanism 20. The window assembly mechanism 20 comprises a lower structure 22 and an upper structure 21, which perform as a horizontal carrier of the transparent window 11 and as a jig to the lower structure 22 and the transparent window 11, respectively.

Referring now to FIG.3, an exploded view of the window assembly mechanism 20 according to the present invention is illustrated. The lower structure 22 for carrying aforesaid transparent window 11, further comprises a left-side plate 222 and a right-side plate 221. The left-side plate 222 is a thin-wall plate with a straight cutout along its upper right side to act as a holder to the left side of the transparent window 11. The right-side plate 221 , which is a symmetric component to the left-side plate 222 along the center line of the transparent window 11 and is located parallel to the leftside plate 222, also has a straight cutout along its upper left side to hold the right side of the transparent window 11.

Aforesaid plates 221 and 222 form a carrier, holding the transparent window 11 at its right and left sides, and provide considerably side extruding space for adjoining with other components of the scanner as well as the upper structure 21.

The upper structure 21, which cooperates with the lower structure 22 to clamp firmly the transparent window 11 upon the straight cutout of the rightside plate 221 and the left-side plate 222 of the lower structure, further comprises a first plate 213, a second plate 214, and a third plate 215.

The first plate 213 is mounted on top along the conjunction line formed by the left side of the transparent window 11 and the right-side plate 221, and is secured to the side extruding of the right-side plate 221.

The second plate 214, which is a symmetric component to the first plate 213, is mounted on top along the conjunction line formed by the right side of the transparent window 11 and the left-side plate 222, and is also secured to the side extruding of the left-side plate 222.

The third plate 215, located preferably perpendicular to both the first plate 213 and the second plate 214, is mounted along top side of the transparent window 11, with a length enough to get across the left side and right side of the transparent window 11. Both ends of the third plate 215 are fixed firmly on top to the side extruding of the left-side plate 222 and the right-side plate 221.

Basically, an upper structure 21 with the first plate 213 and the second plate 214 is good enough to hold the transparent window 11 in between.

However, including the third plate 215 will make the upper structure 21 more concrete and will provide better stiffness.

Moreover, it is preferable that the third plate 215 further comprises an edge stop 2151 extruding downward from lower front edge of the third plate 215 to act as a restraint wall for top edge of the transparent window 11.

Such a design will be helpful in positioning the transparent window 11.

For a better purpose of connection between the first plate 213 and the third plate 215, also between the second plate 214 and the third plate 215, both ends of the third plate 215 further have step-shape edges 2152 and 2153 to engage with the counter step-shape edges 2131 and 2141 at top-side ends of the first plate 213 and the second plate 214, respectively.

Preferably, all the connection between the upper structure 21 and the lower structure 22 can be carried out by screws, as illustrated in FIG.3.

Thus, if re-adjusting the surface flatness is necessary during maintenance, it is easy to regain a satisfactory condition by re-fastening those screws or by adding washers if necessary.

While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in fonn and detail may be without departing from the spirit, nd scope of the present invention.

Claims

What we claimed is:

1. A window assembly mechanism for an optical scanner, which is structured by a plurality of substantial plates to hold securely a transparent window in the middle whereof, comprising: a lower structure for carrying said transparent window, further comprising, a left-side plate, which has a straight cutout along its upper right side to hold the left side of said transparent window, and a right-side plate, which is located symmetrically and parallel to said left-side plate along the center line of said transparent window, having a straight cutout along its upper left side to hold the right side of said transparent window; and an upper structure for cooperating with said lower structure to hold firmly said transparent window between said lower and upper structure, further comprising, a first plate, which is mounted on top along the conjunction line of said left side of said transparent window and said right-side plate and is secured to said right-side plate, and a second plate, which is mounted on top along the conjunction line of said right side of said transparent window and said left-side plate and is secured to said left-side plate.

2. The window assembly mechanism for an optical scanner according to claim 1, wherein said upper structure further comprises a third plate, mounted along top side of said transparent window and a length to cross the left side and right side of said transparent window, and fixed firmly on top to said left-side plate and right-side plate at both ends of said third plate.

3. The window assembly mechanism for an optical scanner according to claim 2, wherein said third plate further comprises an edge stop extruding downward from lower top edge of said third plate to be utilized as a restraint wall for top edge of said transparent window.

4. The window assembly mechanism for an optical scanner according to claim 2, wherein the right end of said third plate further has a step-shape edge to engage with the counter step-shape edge at one end of said first plate.

5. The window assembly mechanism for an optical scanner according to claim 2, wherein the left end of said third plate further has a step-shape edge to engage with counter step-shape edge at one end of said second plate.