JP2000347318A - Document holding device and document reading device - Google Patents

Abstract

(57) [Problem] To provide a document pressing device capable of always keeping a press-contact sheet member in close contact with the entire surface of a document without being affected by a warped shape of a document pressing plate and preventing the document from floating. An image reading device is provided. A document pressing device for pressing a document (S) placed on a contact glass (1) in a document pressing device for bringing the document (S) into close contact with the contact glass (1).
And a resilient member 3 between the original press plate 4 and the press contact sheet member 2 for fixing the press member 4 to the contact glass surface. The document pressing plate 4 is disposed only in the vicinity of the lowermost surface of the warp shape of the document pressing plate 4 within the arrangement range of the pressing sheet member 2, and the pressing sheet member 2 is fixed to the document pressing plate 4 via only the elastic member 3. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an original pressing device for pressing an original on a contact glass in a copying machine, an image scanner, or the like, and an image reading apparatus provided with the same, and more particularly, to the prevention of floating of the original due to warpage or deformation of an original pressing plate. About.

[0002]

2. Description of the Related Art In an image reading apparatus such as an image scanner, an original S is placed on a contact glass 50 as shown in FIGS. It is for reading the written information optically. At this time, the document S is pressed by the document pressure plate 52 so that the document S does not float from the contact glass 50.

A pressure contact sheet member 54 is fixed to the document pressing plate 52 via an elastic member 53. The document pressing plate 52 is generally formed of a resin or the like, and the elastic member 53 is provided with a sponge of open-cell foam. It is used. Further, a resin sheet is used for the press-contact sheet member 54. Then, an adhesive member such as a double-sided tape is attached to both surfaces of the elastic member 53, and a pressure contact sheet member 54 is attached to the elastic member 53, and then the elastic member integrated with the pressure contact sheet member 54 on the back side of the document pressing plate 52. The method of fixing 53 is common.

[0004]

When resin is used for the original pressing plate 52, warping may occur depending on molding conditions. At this time, when the entire surface of the sponge, which is an elastic member, is adhered to the original pressing plate with an adhesive tape or the like, each of the sponge and the press-contact sheet member 54 is deformed following the warpage of the original pressing plate 52 as shown in FIGS. (Fig. 13 is a downward warped state, Fig. 14
Indicates an upwardly warped state). Although the direction of the warpage can be controlled to some extent by the molding conditions such as the position of the gate and the cooling method, it is difficult to add the amount of the warp to zero.

When these deformations occur in the press-contact sheet member 54, a gap is generated between the press-contact sheet member 54 and the contact glass 50, and it is difficult to uniformly adhere the document S to the contact glass 50. At this time, if the original S has a curl or the like, the original will float.

There is a problem that the floating of the document causes image deterioration such as out-of-focus and unevenness in density due to a change in the reflection angle of the document. In particular, when a contact-type image sensor is used as the reading unit 51, these effects appear more remarkably.

As a means for solving these problems, FIG.
As shown in (a), there is a method in which the shape of the elastic member 53, which is a sponge, is manufactured according to the shape of the document pressing plate 52, but it is necessary to make a dedicated part and a manufacturing die, which increases the cost.
Further, as shown in FIG. 15 (b), the sponge 53a is
There is a method of maintaining the flatness of the press-contact sheet member 54 by measuring the amount of warpage of the document pressure plate 52 and adjusting the thickness of the sponge 53a from this numerical value.

However, the amount of warpage of the document pressure plate 52 varies depending on molding conditions, and it is necessary to grasp the amount of warpage of the document pressure plate 52 each time, and it is necessary to prepare several types of sponge thickness.

As disclosed in Japanese Patent Application Laid-Open No. 7-43841, there is a method in which another document pressing sheet is interposed between a document pressing plate and a contact glass to bring the document into close contact with the contact glass. Each time the document is replaced, both the document pressure plate and the document holding sheet must be opened and closed, and there is a problem that the operation is troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to always bring a press-contact sheet member into close contact with the entire surface of a document without being affected by the warped shape of the document pressure plate.
An object of the present invention is to provide a document pressing device capable of preventing the document from floating, and an image reading device provided with the document pressing device.

[0011]

A typical configuration according to the present invention for achieving the above object is a document holding device for bringing a document into close contact with a contact glass surface, and a document placed on the contact glass surface. A document pressure plate for pressing
A press-contact sheet member for pressing the document on the contact glass surface; and an elastic member between the document press plate and the press-contact sheet member for fixing the both, and the elastic member is formed of the press-contact sheet member. The document pressing plate is disposed only in the vicinity of the lowermost surface of the warped shape within the arrangement range, and the press-contact sheet member is fixed to the document pressing plate via only the elastic member.

In the above configuration, the press-contact sheet member maintains its flatness without transmitting the warpage or distortion of the document pressing plate. The original can be brought into close contact with the contact glass in the entire range by the weight of the original pressing plate. In addition, since the pressure-contact sheet member is not affected by the magnitude of the warpage of the document pressing plate, it is not necessary to quantitatively manage the warpage.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment] FIGS. 1 to 7 show a first embodiment. FIG. 1A is a schematic configuration diagram of a scanner as an image reading apparatus, and FIG. 4 is a cross-sectional view illustrating a configuration of a document portion.

First, the structure of the image reading apparatus will be briefly described. As shown in FIG. 1, a document S placed on the surface of a contact glass 1 is made up of a press-contact sheet member 2 and an open-cell foam. The document is pressed against the contact glass surface by the document pressing plate 4 via the elastic member 3.

The original S pressed against the contact glass surface is read by the reading means 5 as original information.
Specifically, as shown in FIG. 1B, the original S is a lamp,
The light is illuminated linearly by a light source 6 such as an LED, and the light from the original is focused on a photoelectric conversion element 9 via a mirror 7 and a lens 8. The light source 6, mirror 7, lens 8, and photoelectric conversion element 9 are configured as a unit, and are driven relative to the document S by driving a motor 10 along a guide 11 in a direction perpendicular to the longitudinal direction of the photoelectric conversion element 9. (Scan) and optically reads a planar document image.

Incidentally, a contact type image sensor using a rod lens array as the lens 8 may be used.

Next, the structure of the original pressing by the original pressing plate 4 will be specifically described. The document pressure plate 4 is rotatably attached to the apparatus main body 12 via a rotation fulcrum 13.
In the present embodiment, the original pressing plate 4 is formed of ABS resin, the elastic member 3 is made of maltprene, and the press-contacting sheet member 2 is made of a PET resin sheet.

The elastic members 3 are fixed to the four corners of the back surface of the original pressing plate near the lowermost surface of the original pressing plate 4 in the arrangement range of the pressing sheet member 2 in the form of flying stones. It is fixed with.

When the original pressing plate 4 is formed of resin, FIG.
As shown in (a) and (b), warpage may occur (see FIG. 2).
Indicates an example having downward warpage). Since the press-contact sheet member 2 is held at the four corners as described above, the central portion is not affected by the press plate-shaped interference. As a result, the press-contact sheet member 2 adheres to the contact glass 1 over the entire range due to its flatness without following the shape of the document pressing plate 4. For this reason, the original S placed on the contact glass surface is flattened by the weight of the original pressing plate 4 and the flatness and rigidity of the press-contact sheet member 2 so that unevenness such as curl is crushed, and the original S comes into close contact with the contact glass surface over the entire range. .

In this embodiment, since the flatness of the press-contact sheet member 2 is not affected by the magnitude of the amount of warpage of the document pressure plate 4, it is necessary to quantitatively control the amount of warpage as long as the warpage direction is controlled. Disappears.

In this embodiment, the elastic member 3 is made of moltoprene, but the present invention is not limited to this. That is, a coil spring may be used as the elastic member. Also,
The press contact sheet member 2 may be a sheet material having sufficient flatness and rigidity to press the document S against the contact glass surface, and may be, for example, a PVC sheet or a PPE sheet. Since the elastic member 3 may be arranged near the lowermost surface of the warped shape of the document pressing plate 4, the same effect can be obtained even if it is provided at three places as shown in FIGS.

Normally, a reinforcing rib is arranged on the back surface of the document pressing plate 4. In this case, since the rib surface also follows the warped shape of the document pressing plate 4, the elastic member 3 may be disposed on the lowermost surface on the rib 14 as shown in FIGS. 4 (a) and 4 (b). 5 (a) and 5 (b), the height (thickness) of the elastic member 3 is set higher than the height of the rib 14, and the elastic member 3 excluding the rib portion has a warped shape of the document pressing plate 4. The same effect can be obtained even if it is arranged on the lowermost surface.

It is preferable that these elastic members 3 are located on the same plane with respect to the contact glass surface when the original pressing plate 4 is closed. There is no problem because the member 3 is absorbed by expansion and contraction. It is desirable that the heights (thicknesses) of the elastic members 3 are all the same, but there is no problem even if there are some steps.

FIGS. 6A and 6B show an example in which the document pressure plate 4 has an upward warp with respect to the document S. FIG. In this case, an elastic member 3 made of maltprene is disposed at the center, which is the lowermost surface of the document pressing plate 4, and the press-contact sheet member 2 is
Of the original.

Also in this case, the pressure contact sheet member 2 comes into close contact with the contact glass 1 over the entire range due to its flatness without following the shape of the document pressure plate 4. As a result, the document S on the surface of the contact glass 1 can be brought into close contact with the contact glass 1 over the entire range. still,
In FIG. 6, the elastic member 3 is arranged only at the center of the document pressing plate 4. However, as shown in FIGS. 7 (a) and 7 (b), the elastic member 3 protrudes below the height of the central portion around the document pressing plate 4. The same effect can be obtained by providing the projection surface 4a described above and disposing the elastic member 3 on the projection surface 4a.

[Second Embodiment] FIGS. 8A and 8B show a second embodiment of the present invention. That is, the document pressing plate 4 is warped downward with respect to the document surface, and the elastic member 3 is a maltprene sheet made of an integrated open-cell foam. The press-contact sheet member 2 is fixed to the original surface side of the open-cell foam with a double-sided tape and is integrated. The open-cell foam is fixed to the document pressure plate 4 by fixing portions 3a provided in the vicinity of the four corners which are the lowermost surfaces of the warp shape of the document pressure plate 4 within its own arrangement range. Thus, the press-contact sheet member 2 maintains the flatness without following the shape of the document pressing plate 4, and the weight of the document pressing plate 4 allows the document S to be in close contact with the surface of the contact glass 1 in the entire range. In this embodiment, since the pressure contact sheet member 2 and the elastic member 3 which is an open-cell foam are integrated, the weight and flatness of the elastic member 3 can also be used, and the original S is brought into close contact with the contact glass 1. The effect of this is even higher than in the first embodiment.

FIGS. 9A and 9B show an example in which the document pressure plate 4 is warped upward with respect to the document surface. That is, the fixing portion 3a is disposed at one position near the center, which is the lowermost surface of the warp shape of the document pressing plate 4. Also in this case, the press-contact sheet member 2
The document S can be brought into close contact with the surface of the contact glass 1 over the entire range by the weight of the document pressure plate 4 without following the shape of the document pressure plate 4.

[Third Embodiment] FIGS. 10A and 10B show a third embodiment of the present invention. That is, the document pressing plate 4 is warped downward with respect to the document surface. The elastic member 3 made of open-cell foam is fixed to the entire back surface of the document pressing plate 4. For this reason, the elastic member 3 follows the shape of the warpage of the document pressing plate 4. On the other hand, the pressure contact sheet member 2 is provided with fixing portions 2a near four corners, which are the lowermost surfaces of the elastic member 3. In this case, the four corners of the press-contact sheet member 2 are held, and the central portion is not affected by the interference of the shapes of the document pressing plate 4 and the elastic member 3. As a result, the press-contact sheet member 2 is
Of the original S by the weight of the original pressing plate 4 without imitating the shape of the original S.
Can be adhered to the surface of the contact glass 1 in the entire range.

As shown in FIGS. 11 (a) and 11 (b), even when the elastic member 3 which is an open-cell foam has an upward curl or the like, it is the lowermost surface of the warped shape of the elastic member 3. By providing the fixing portion 2a with the press contact sheet member 2 at the center portion, the flatness of the press contact sheet member 2 can be maintained.
FIGS. 12 (a) and 12 (b) show an example in which the original pressing plate 4 is warped upward with respect to the original surface. By providing the two fixing portions 2a, the same effect can be obtained.

In the above-described embodiment, the scanner is exemplified as the image reading apparatus. However, the present invention can be similarly applied to a copying machine other than the scanner.

[0032]

The present invention is constructed as described above.
The press-contact sheet member maintains the flatness without transmitting the warpage or distortion of the document pressing plate. The original can be brought into close contact with the contact glass in the entire range by the weight of the original pressing plate. Further, since the pressing sheet member is not affected by the amount of warpage of the document pressing plate, it is not necessary to quantitatively manage the amount of warpage.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram of an image reading apparatus according to a first embodiment, and FIG. 1B is an explanatory cross-sectional view illustrating a configuration of a document portion.

FIG. 2A is a perspective explanatory view of an embodiment in which a press-contact sheet member is fixed via elastic members disposed at four corners of a document pressure plate that is warped downward, and FIG. 2B is a sectional explanatory view of the embodiment.

3A is a perspective explanatory view of an embodiment in which a press-contact sheet member is fixed via elastic members disposed at three places on a document pressing plate that is warped downward, and FIG. 3B is a sectional explanatory view of the embodiment.

4A is a perspective explanatory view of an embodiment in which a press-contact sheet member is fixed via elastic members disposed at four corners of a document pressure plate having ribs on the back surface and warped downward, and FIG. It is.

FIG. 5A is a perspective explanatory view of an embodiment in which a press-contact sheet member is fixed via elastic members disposed at four corners of a document pressure plate having a rib on a back surface and warped downward, and FIG. It is.

6A is an explanatory perspective view of an embodiment in which a press-contact sheet member is fixed via an elastic member disposed at a central portion of a document pressing plate that is warped upward, and FIG. 6B is an explanatory cross-sectional view thereof.

7A is a perspective explanatory view of an embodiment in which a press-contact sheet member is fixed via elastic members arranged at four corners of an original pressing plate that is warped upward, and FIG. 7B is a sectional explanatory view of the embodiment.

8A is a perspective explanatory view of an embodiment in which an elastic member to which a press-contact sheet member is fixed is fixed to a downwardly warped document pressing plate at fixing portions at four corners, and FIG. 8B is a cross-sectional explanatory view of the embodiment. .

9A is a perspective explanatory view of an embodiment in which an elastic member to which a press-contact sheet member is fixed is fixed to an upwardly warped document pressing plate at a fixing portion at a central portion, and FIG. 9B is a cross-sectional explanatory view of the embodiment. is there.

10A is a perspective explanatory view of an embodiment in which a press-contact sheet member is fixed at four corner fixing portions to a document pressure plate having an elastic member fixed to the back surface, and FIG. 10B is a cross-sectional explanatory view thereof. It is.

11A is a perspective explanatory view of an embodiment in which a press-contact sheet member is fixed at a central fixing portion to a document pressing plate having an elastic member that is warped downward and an upwardly warped rear surface, and FIG. FIG.

12A is an explanatory perspective view of an embodiment in which a press-contact sheet member is fixed to a document pressing plate having an elastic member fixed to the back surface at a central fixing portion, and FIG. 12B is an explanatory cross-sectional view thereof. It is.

13A is a perspective view of a scanner according to the related art, in which a document pressing plate is warped downward, and FIG. 13B is a sectional view of the apparatus.

FIG. 14A is a perspective view of a scanner according to the related art, in which a document pressing plate is warped upward, and FIG. 14B is a sectional view of the scanner.

FIG. 15A is an explanatory view of a structure for manufacturing a sponge according to the warp shape of the document pressing plate, and FIG. 15B is a diagram illustrating a configuration in which the sponge is divided on the back surface of the document pressing plate and the amount of warpage of the document pressing plate is measured. It is explanatory drawing of the prior art which adjusts the thickness of a sponge.

[Explanation of symbols]

 S: Document 1 ... Contact glass 2 ... Press-contact sheet member 2a ... Fixing part 3 ... Elastic member 3a ... Fixing part 4 ... Document pressing plate 4a ... Projection surface 5 ... Reading means 6 ... Light source 7 ... Mirror 8 ... Lens 9 ... Photoelectric conversion element 10… Motor 11… Guide 12… Device body 13… Rotating fulcrum 14… Rib

Claims (4)

[Claims] An original pressing plate for pressing an original placed on the contact glass surface, and a pressing sheet member for pressing the original on the contact glass surface. And an elastic member between the original pressing plate and the press-contact sheet member for fixing the both, and wherein the elastic member is located near the lowermost surface of the warped shape of the original press plate within the arrangement range of the press-contact sheet member. Place only
An original pressing device, wherein the pressing sheet member is fixed to the original pressing plate only via the elastic member. 2. A document pressing device for bringing a document into close contact with a contact glass surface, a document pressing plate for pressing a document placed on the contact glass surface, and a press-contact sheet member for pressing the document onto the contact glass surface. And an elastic member between the original pressing plate and the press-contact sheet member for fixing the original pressing plate member, wherein the fixing position of the elastic member to the original pressing plate is set within the range of disposition of the elastic member. A document pressing device disposed only in the vicinity of the lowermost surface of the warped shape. 3. A document pressing device for bringing a document into close contact with a contact glass surface, a document pressing plate for pressing a document placed on the contact glass surface, and a press-contact sheet member for pressing the document onto the contact glass surface. And an elastic member between the original pressing plate and the press-contact sheet member for fixing the both, wherein the fixing position of the press-contact sheet member to the elastic member is within the arrangement range of the press-contact sheet member. An original pressing device which is arranged only in the vicinity of the lowermost surface of a warped shape of an elastic member fixed to an original pressing plate. 4. An image reading apparatus for reading document information by bringing a document into close contact with a contact glass surface, the document pressing device according to claim 1, and the document pressing device contacting the contact glass with the document pressing device. An image reading apparatus, comprising: reading means for optically reading a closely adhered document.