JP2007019895A - Copyholder, image scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copyholder by which lifting of a manuscript can be prevented at the same level at the side of a rotational supporting point 24 of a manuscript pressing plate 20 and in a front edge side thereof, and further impact noises and vibrations are hard to be generated when clamping the manuscript by the manuscript pressing plate 20, in such a fashion that the manuscript pressing plate 20 is lifted by a hand and then the hand is taken off from the manuscript pressing plate 20 to drop the plate naturally onto the manuscript, and furthermore displacement of the manuscript is hard to occur. <P>SOLUTION: Elastic members 22 and 21 are stuck to the side of the rotational supporting point 24 of the manuscript pressing plate 20 and the front edge side thereof, respectively, to support a sheet member 23. Heights of the elastic members 22, 21 are each more than a distance from the manuscript pressing plate 20 in its closed state to a contact glass 10 to ensure the heights, so that a clearance is secured between the sheet member 23 and the contact glass 10 at the side of the front edge when the sheet member contacts with the contact glass 10 at the side of the rotational supporting point 24. Further, in a process of turning the manuscript pressing plate 20 to press the contact glass 10, a compressive deformation amount of the elastic member 22 is larger than that of the elastic member 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document pressing device that is mounted on a copying machine, an image scanner, other office machines, etc., and presses a document for image reading, and an image reading apparatus or image forming apparatus provided with the document pressing device. The present invention relates to a technique for preventing a document from being lifted when a sheet is pressed against contact glass (transparent member).

  Image reading devices such as copiers, image scanners, and other office machines read an image of a document placed on a contact glass surface optically and scanningly by an image reading unit that reads a line image, and if necessary, electrically Convert to signal or image data. In the image reading device, when the document is lifted from the contact glass surface, the optical system of the image reading unit is out of focus and a clear image cannot be read. Is provided.

  Patent Document 1 shows a document pressing device mounted on an image scanner. Here, a sheet member (contact member) that presses the back surface of the document placed on the contact glass surface in a planar shape is attached to a support member that is arranged to be rotatable with respect to the contact glass. A sponge elastic member is arranged between the sheet member and the support member. When the original is sandwiched between the sheet member and the contact glass by rotating the support member, the elastic member is compressed and deformed, and the sheet member Is in surface contact with the back of the document.

  In addition, elastic members are disposed on the shaft side and the front end side of the support member, but the width of the shaft side elastic body member is narrowed so that the elastic coefficient (and document pressing force) is smaller than that of the elastic member on the front end side. It is set.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a document reading device mounted on a copying machine that is an image forming apparatus. Here, a document transport device (ADF) for passing a document on the flow reading contact glass is disposed on the image reading portion where the flow reading contact glass is disposed adjacent to the book reading contact glass, and is rotated. Thus, the document conveying device that can be opened and closed vertically also serves as a support member that presses the document against the book reading contact glass. The original placed on the book reading contact glass and the original conveyed by the original feeder are read by a common image reading means.

Japanese Patent Laid-Open No. 2001-22010 JP 2003-222959 A

  In the document pressing device, it is desirable that the pressing force on the supporting member is made as small as possible, while the sheet member is surely in contact with the four corners of the document and the entire document surface is in uniform contact with the contact glass.

  However, the document pressing device disclosed in Patent Document 1 has different pressing forces on the shaft side of the support member on the shaft side and the leading end side, and the pressing force on the shaft side is set smaller than that on the leading end side. Even if the whole cannot be pressed against the contact glass with a uniform pressing force, and the folded or curled document can be stretched and pressed on the tip side, the same folded document on the shaft side or the same The curled document may not be stretched and pressed in the same way.

  In addition, when an original is placed on the contact glass surface with the support member supported by hand, and the support member is rotated spontaneously by releasing the hand, the shaft-side elastic member functions sufficiently as a brake. In other words, the sheet member on the tip side collides with the contact glass at a high speed while the compressive stress of the elastic member on the shaft side is small, generating a large impact sound and vibration.

  In addition, when the support member is lowered while pressing the front side (front end side) of the document placed on the contact glass surface with the hand, before the document is pressed on the back side (axis side), Since the paper is caught, there is a possibility that the document is displaced on the contact glass when the hand is pulled out.

  The present invention can equally prevent the document from being lifted on the shaft side and the tip side of the support member, and it is difficult to generate an impact sound or vibration when the document is naturally held by releasing the hand from the support member. An object of the present invention is to provide a document pressing device in which when the front side of a document is pressed by hand and the support member is lowered, the back side of the document is pressed against the sheet member before the hand is caught and the document is not easily displaced. It is said.

  The document pressing device according to the present invention includes a contact member that presses the document placed on a transparent member on which the document is placed, and a contact member that is pivotable with respect to the transparent member and applies pressure to the contact member. And a resilient member that elastically supports the contact member on the shaft side and the tip side of the support member, respectively, and the elastic member on the shaft side and the tip side. Is set to a height at which a gap is secured between the contact member and the transparent member on the distal end side when the contact member contacts the transparent member on the shaft side. The amount of compressive deformation of the elastic member in the process of rotating the support member and pressing the transparent member is larger on the shaft side than on the tip side.

  The elastic member may include a shaft-side elastic member disposed on the shaft side and a tip-side elastic member disposed on the tip side. In this case, the support member may The elastic coefficient of the shaft side elastic body member in the pressed state in which the transparent member is pressed × the amount of compressive deformation is set to be greater than or equal to the elastic coefficient of the tip side elastic body member × the amount of compressive deformation. It is desirable that

  In the document pressing device of the present invention, when the supporting member is lowered and the document on the transparent member surface is pressed by the contact member, the back side (axis side) of the contact member precedes the front side (front end side). At the stage where the back side is pressed, a considerable gap is secured between the contact member on the near side and the document, so the contact member precedes the hand or finger holding the near side of the document. There is no pressing. Accordingly, the hand or finger can be retreated while the back side of the document is pressed by the contact member, and the document is unlikely to be displaced on the transparent member along with the retraction.

  Further, a large amount of compression deformation of the elastic member on the back side (shaft side) is ensured to ensure pressing on the back side of the document, and the pressing force is equal to or higher than the front side (front end side). Therefore, the pressing state of the document does not vary or loosen even on the far side where it is difficult to reach.

  In the process in which the support member rotates and descends in a free-fall manner, the elastic member on the shaft side is compressed and deformed first, generates a compressive stress, brakes the lowering of the support member, and Since the speed at which the contact member comes into contact with the document or the transparent member is reduced, it is difficult for the impact sound and vibration associated with the front end side collision to occur.

  1 is an external view of an image reading apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory view of a configuration of an image reading unit, FIG. 3 is an explanatory view of a document pressing state, FIG. 4 is an explanatory view of a design size of an elastic member, FIG. 5 is an explanatory diagram of the process of rotating the original cover.

  The image reading apparatus G according to the present embodiment includes a document pressing unit F that is a document pressing device, for example, a contact glass 10 that is a transparent member, a sheet member 23 that is a contact member, and a document pressing unit that is a support member, for example. It has the board 20 and the elastic members 21 and 22 which are elastic bodies members.

<Image reading device>
As shown in FIG. 1, the image reading apparatus G presses, for example, a document 11 placed on a contact glass 10 of a document pressing portion F into a sheet shape by a document crimping plate 20 to which a sheet member 23 is attached. For example, an image on the lower surface of the document 11 is scanned and read by the reading unit 12 that moves under the contact glass 10.

  A transparent flat contact glass 10 is fixed to the upper surface of the apparatus body 1. The document crimping plate 20 is pivotally supported by a rotation fulcrum 24 provided in the apparatus main body 1 and can be rotated up and down by rotating with respect to the contact glass 10 (apparatus main body 1). A square pillar-shaped elastic member 22 is attached to the rotation fulcrum 24 side of the original pressure plate 20 using a double-sided adhesive tape, and a square pillar-like elastic member 21 is similarly attached to the original pressure plate 20 on the opposite end side. It is attached. A sheet member 23 is affixed to the surface of the elastic members 21 and 22 using a double-sided adhesive tape, and the sheet member 23 is supported on the original cover 20 via the elastic members 21 and 22.

  A guide member 18 that guides the reading unit 12 and supports it so as to be movable is fixed below the contact glass 10 of the apparatus main body 1. A drive motor 17 disposed on one end side of the guide member 18 drives a drive belt 16 fixed to the reading unit 12 and moves the reading unit 12 along the guide member 18 by forward and reverse rotation thereof.

  As shown in FIG. 2, the reading unit 12 can insert a cylindrical guide member 18 and hold it without rattling, and can move under the contact glass 10 in the direction of the arrow in the figure. The reading unit 12 has a pair of rod-shaped light sources 13 arranged in the front and rear in the moving direction with a lens 14 in which innumerable lens elements are arranged in a direction perpendicular to the paper surface. The light source 13 is a thin linear xenon tube or the like, but may be configured by an LED that is a light source and a light guide.

  At the height position where the document placement surface of the contact glass 10 is projected by the lens 14, a photoelectric conversion element 15 that reads a line image by arranging an infinite number of light receiving elements such as a contact image sensor (CIS) is arranged. Is done. The lens 14, the light source 13, and the photoelectric conversion element 15 are fixedly disposed on the bowl-shaped casing and move together.

  The reading unit 12 projects the image surface of the document 11 illuminated by the light source 13 onto the photoelectric conversion element 15 by the lens 14, reads a line image with the photoelectric conversion element 15, and moves the image unit 11 with the movement of the reading unit 12. Scan and read the image.

  As shown in FIG. 1, the original 11 placed with the reading surface facing the contact glass 10 is moved by the elastic members 21 and 22 attached to the original crimping plate 20 so that the sheet member 23 and the original 11 are separated. The contact glass 10 is pressed to bring the document 11 into close contact with the contact glass 10.

  The document 11 pressed against the surface of the contact glass 10 is scanned and read by the reading unit 12. Specifically, as shown in FIG. 2, the document is irradiated linearly by the light source 13, and the reflected light of the document is imaged on the photoelectric conversion element 15 through the lens 14. The light source 13, the lens 14, and the photoelectric conversion element 15 constitute a reading unit 12 as a unit, and a driving force is transmitted to the reading unit 12 through a driving belt 16 fixed to the reading unit 12 by driving a motor 17. The reading unit 12 moves (scans) relative to the document in the direction orthogonal to the longitudinal direction of the photoelectric conversion element 15 along the guide 18 to optically read the image of the document 11.

<Document holding part>
As shown in FIG. 3, the document pressing plate 20 has a closed position (solid line in FIG. 3) for pressing the document 11 placed on the surface of the contact glass 10 through the rotation fulcrum 24 against the apparatus body 1. It is rotatably attached to an open position (FIG. 3 two-dot chain line) for releasing the press.

  The original cover 20 is integrally formed of ABS resin, and the elastic members 21 and 22 are formed by cutting a sponge material such as maltoprene into a rectangular column having a predetermined width and length. The sheet member 23 is formed by cutting a white ABS resin sheet into a predetermined size. The elastic members 21 and 22 can obtain the same pressing effect by using a resin or metal spring instead of the sponge.

  The elastic members 21 and 22 are arranged at two positions between the original cover plate 20 and the sheet member 23, and are fixed to the sheet member 23 and the original cover plate 20. The elastic member 22 near the rotation fulcrum 24 of the original cover 20 has a smaller width and the same thickness as the elastic member 21 far from the rotation fulcrum 24.

  FIG. 4 is a diagram for explaining the design size of the elastic member, which is indicated by a two-dot chain line in the state of being pressed in the state of being pressed in the closed state of the original pressure plate shown in FIG. As shown in FIG. 4, the elastic members 21 and 22 are both made of the same material, and the size of the actual elastic member 22 that is not pressed is: width: a, height: b, length: c ( Similarly, the size of the elastic member 21 is width: 2a, height: b, and length: c (not shown). The designed member heights of the elastic members 21 and 22 are the same, and both are higher than the distance between the surfaces of the document pressing plate 20 and the contact glass 10 in the closed state.

  The pushing amount (elastic deformation amount) in the process of changing the original cover 20 from the open state to the closed state is 2x for the elastic member 22 close to the rotation fulcrum 24 and x for the elastic member 21 far from the rotation fulcrum 24. In addition, a fixed surface height on the side of the original pressure plate 20 and a mounting surface step d (or member heights of the elastic members 21 and 22) are set.

  Since the elastic members 21 and 22 are made of the same material and differ only in width, if the spring constant of the elastic member 22 near the rotation fulcrum 24 is k, the spring constant of the elastic member 21 far from the rotation fulcrum is 2k.

  Therefore, the pressing force in the process of changing the original pressing plate 20 from the open state to the closed state obtained by multiplying each pressing amount and the spring constant is 2x * k by the elastic member 22 near the rotation fulcrum 24 and far from the rotation fulcrum. The elastic member 21 becomes x * 2k, and the sheet member 23 presses the contact glass 10 with an equal pressing force of 2 kx.

  With the setting as described above, it is possible to eliminate the difference in the pressing ability of the folded document and the curled document on the side close to and far from the rotation fulcrum 24 of the sheet member 23, and press the document evenly against the contact glass 10. Can do.

  When the original cover 20 is closed without applying a force from the open position to the closed position, the sheet member 23 on the side close to the rotation fulcrum 24 first contacts the original 11 or the contact glass 10 as shown in FIG. It will be. At this time, since the speed of the sheet member 23 is slow on the side close to the rotation fulcrum, the elastic member 22 on the rotation fulcrum 24 side is positively compressed and deformed in the process of coming into contact with the side with the slow drop speed first and reaching the closed position. Can absorb impact and reduce impact noise. Further, since the force that deforms the elastic member 22 on the side near the rotation fulcrum acts as a drag force against the document pressing plate 20 until the sheet member 23 on the side far from the rotation fulcrum lands from that state, The falling speed of the crimping plate 20 is reduced, and the impact sound when the document crimping plate 20 moves to the closed position can be reduced.

  In addition, with the above configuration, since the original can be pressed by the sheet member 23 in a state of being opened more than the conventional original press plate 20, better manuscript placement operability can be obtained. Even in an automatic document feeder (ADF) or the like where it is difficult to provide a joint such as the above, document placement is simple and reliable.

<Other embodiments>
FIG. 6 is an explanatory view of a document pressing portion according to another embodiment, and FIG. 7 is an explanatory view of a document pressing portion according to still another embodiment. In the embodiment shown in FIGS. 6 and 7, only the elastic members 21 and 22 and the sheet member 23 of the image reading apparatus shown in FIGS. 1 and 2 are changed, and other common members are denoted by the same reference numerals. The detailed description will be omitted.

  In the document pressing portion F described above, the elastic members are disposed at two locations near the rotation fulcrum 24 and on the far side, but as another method for obtaining the same effect, as shown in FIG. Between the crimping plate 20 and the sheet member 23, a plurality of elastic members 25a and 25b may be provided between the elastic member 22a closest to the rotation fulcrum 24 and the farthest elastic member 21a.

  That is, the height of the elastic member 22a closest to the fulcrum 24 is set higher than that of the farthest elastic member 21a, and the height of the intermediate elastic members 25a and 25b is set to be the farthest elastic member 22a and the elastic member 21a farthest from the fulcrum 24. The sheet member 11 is attached so that it is on a straight line connecting the heights of the pasting surfaces. Then, with the original cover 20 closed, the widths of the elastic members 21a, 22a, 25a, 25b (the product of the spring constant and the pressing amount) are equal so that the pressing forces of the elastic members 21a, 22a, 25a, 25b are equal. And material).

  As a result, the effect of improving the document pressing performance, the effect of improving the document placement operability, and the effect of reducing the operation sound can be obtained in the same manner as in the above-described embodiment.

  Further, as shown in FIG. 7, when the original crimping plate 20 is closed, the sheet member 23 is warped as indicated by the broken line P2, and the original and the sheet member 23 are separated from each other at the center portion of the contact glass 10, and the pressing force is lost. In this case, warpage may be canceled by the intermediate elastic members 25c and 25d.

  That is, a plurality of elastic members 25c and 25d are provided between the elastic member 22b close to the rotation fulcrum 24 and the distant elastic member 21b, and the straight line P1 connecting the sheet attaching surface heights of the closest elastic member 22b and the farthest elastic member 21b. The intermediate elastic members 25c and 25d are set to be higher than the (dashed line) (shown by solid lines).

  Alternatively, the elastic members 22b close to the rotation fulcrum 24 and the distant elastic members 21b may be made equal in height so that the intermediate elastic members 25c and 25d are higher than the elastic members 21b and 22b.

  Also by these methods, the effect of improving manuscript placement operability and the effect of reducing operation sound can be obtained in the same manner.

<Application to image forming apparatus>
FIG. 8 is an explanatory diagram of the configuration of the image forming apparatus equipped with the image reading device, and FIG. 9 is an explanatory diagram of the configuration of the image reading device including the document conveying device (ADF). The copier C of the present embodiment is an example of an image forming apparatus that includes, for example, an image reading apparatus A that is an image reading unit and an apparatus main body B that is an image forming unit.

  As shown in FIG. 8, the copier C of the present embodiment has an image reading device A mounted on the upper part of the apparatus main body B, and forms an image of a document read by the image reading apparatus A on a sheet P by the apparatus main body B. To do. The apparatus main body B operates the exposure unit 123 based on the electrical signal and image data of the image to form an electrostatic latent image on the surface of the rotating photosensitive drum 121. The electrostatic latent image is developed (supplied with toner) by the developing device 124 to become a toner image. Thereafter, the sheet P is supplied between the photosensitive drum 121 and the transfer charger 125 at the same timing by the conveying roller 131, and the sheet P contacts the photosensitive drum 121 and passes through the separation charger 126, so that The toner image is transferred from the body drum 121 to the sheet P.

  The cleaner 127 cleans the surface of the photosensitive drum 121 to which the toner image has been transferred, and the charger 122 charges the surface of the photosensitive drum 121 in preparation for the next exposure.

  On the other hand, the sheet P to which the toner image has been transferred is conveyed to the fixing device 129 by the conveying unit 128, and the toner image is fixed on the surface of the sheet P by being heated and pressurized by the fixing device 129. Then, the sheet P on which the toner image is fixed is discharged to the discharge tray 130.

  Under the image forming apparatus B, sheet storage portions 119a, 119b, 119c, and 119d loaded with sheets P of various sizes are arranged. The sheets P in the sheet storage portions 119a, 119b, 119c, and 119d are taken out one by one by the feeding rollers 120a, 120b, 120c, and 120d, and are transferred to the conveying roller 131.

  As shown in FIG. 9, the image reading apparatus A has a document conveying device (ADF) 102 mounted on the upper portion of the image reading unit 1, and can read an image of a document by both a flow reading method and a book reading method. The book reading method has an advantage that the degree of freedom of the form of the original is high and a book-like original or a three-dimensional object can be read. On the other hand, the flow reading method has an advantage that a large amount of sheet-like documents can be automatically processed in a short time.

  On the upper surface of the image reading unit 1, a book reading platen glass 103 on which a document of the maximum size can be placed is provided, and a sink for supporting a document surface of a document for flow reading adjacent to the platen glass 103. A reading glass 104 is provided. A reading unit 105 that reads an image on the original surface is arranged below the flow reading glass 4. The reading unit 105 moves below the original table glass 3 and scans the original placed on the original table glass 3. Is possible.

  The document conveying device 102 is attached to the upper part of the image reading unit 101 with a hinge or the like, and can be rotated up and down with respect to the image reading unit 101. The document conveying device 102 takes in the documents stacked on the document placing unit 110 one by one with the conveying rollers 111 a, conveys them with the conveying rollers 111 b, 111 c, 111 d, and 111 e, and passes them above the reading unit 105. Then, the document whose image has been read is discharged from the conveying roller 111f to the document discharge unit 113.

  On the other hand, when reading an image by the book reading method, an original is placed on an original table glass 103 arranged in the same manner as the contact glass 10 shown in FIG. 1 with the original conveying device 102 lifted upward. Then, the document feeder 102 is lowered to the original position, and the document is pressed against the document table glass 103. Thereafter, when the start switch is operated, the reading unit 105 moves under the platen glass 103 and scans and reads an image on the document surface.

  A sheet member (not shown) having substantially the same size as that of the document table glass 103 is attached to the bottom surface of the document conveying device 102 in the same manner as the document pressing plate 20 shown in FIG. Similar to the sheet member 23 shown in FIG. 1, the sheet member is attached to an elastic member attached to the rotating shaft side and the shaft side of the bottom surface of the document conveying apparatus 102.

  The heights of the elastic members on the shaft side and the front end side are higher than the height from the bottom surface of the document feeder 102 in the closed state to the document table glass 103, as in the document pressing portion F shown in FIG. The heights of the elastic members on the shaft side and the front end side are substantially equal to each other, and the clearance between the sheet member and the platen glass 103 on the front end side when the sheet member contacts the platen glass 103 on the shaft side. The amount of compressive deformation of the elastic member in the process of rotating the document conveying device 102 and pressing the document table glass 103 is larger on the shaft side than on the tip side (FIGS. 4 and 5). reference).

  Therefore, the same effect as that of the document pressing portion F described with reference to FIGS. 1 to 5 is realized.

  The elastic member for attaching the sheet member to the bottom surface of the document conveying apparatus 102 is described with reference to the format described with reference to FIG. 6 and FIG. 7 instead of the format described with reference to FIGS. May be adopted.

<Reference Example Document Crimping Plate>
The document pressing device disclosed in Patent Document 1 has a problem that the pressing state of the document by the sheet member becomes unstable behind the contact glass that cannot be reached. In order to solve this problem, for example, a plurality of original pressing plates are connected to each other with hinges, and a single sheet member is supported on a plurality of points by attaching an elastic member on each member. Also good. In other words, by supporting the sheet member on the original document crimping plate having increased flexibility, it is possible to insert and remove the hand even when the original is pressed by the sheet member.

  However, this structure requires a joint such as a hinge, which increases the number of parts and is expensive, and cannot be used in a document feeder (ADF) or the like where it is difficult to have a joint on the document crimping plate itself. There was a problem.

  On the other hand, in the document reading apparatus of each of the embodiments described above, in a configuration in which the document is brought into close contact with the contact glass surface and the document is read through the contact glass, the document is brought into contact with the contact glass surface in contact with the document. A sheet member for holding the sheet member, a plurality of elastic members for connecting the document crimping plate and the sheet member, and a fulcrum for rotating the document crimping plate to close and close the document crimping plate. The pushing amount of the elastic member by the sheet member differs depending on the rotational radial distance with respect to the fulcrum, and the pushing amount of the elastic member closest to the fulcrum is large on the side farthest from the rotation fulcrum, and the rotation fulcrum. The sheet member on the side can contact the contact glass surface first, the elastic member has at least two kinds of spring constants, and the spring constant of the elastic member is small on the side close to the rotation fulcrum. Therefore, when the original cover is closed, the elastic member close to the pivot point and the elastic member far away from the elastic member are set equal to each other, or the side close to the pivot point is strengthened. When the crimping plate is closed, the sheet pressing force of the sheet member is almost the same at both the position close to the rotation fulcrum and the position far from the rotation fulcrum. There is no difference in the pressing ability of the original, and the original can be pressed evenly against the contact glass.

  In the open position, the gap between the sheet member close to the rotation fulcrum and the original pressure plate is wide, so in the process of dropping the original pressure plate from the open position to the closed position, the side closer to the rotation fulcrum. The side of the sheet member comes into contact with the document or contact glass first, and the side near the rotation fulcrum is slow, so the impact at the time of contact is small, and the side closer to the rotation fulcrum as the document crimping plate approaches the closed position The sheet member is pushed in by the document or contact glass, and the elastic member near the rotation fulcrum is contracted to generate a repulsive force in the direction of preventing the document crimping plate from dropping, so that the document crimping plate reaches the closed position. The speed on the side far from the rotation fulcrum of the document crimping plate and the sheet member is reduced at least, so that in the process of falling movement from the open state to the closed state. It is possible to reduce the impact sound generated Te.

  Further, in the above configuration, as described in the document crimping plate of the reference example, it is possible to start pressing the document with the document crimping plate opened further without providing a joint such as a hinge on the document crimping plate. In the automatic document feeder, the manuscript operability can be improved.

  In other words, in the document pressing portion F in the present embodiment, when the document pressing plate 20 is lowered and the document on the contact glass 10 is pressed by the sheet member 23, the back side (axis side) of the sheet member 23 is the front side (tip). The original is pressed before the side), and a considerable gap is secured between the sheet member 23 on the near side and the original when the back side contacts, so the front side of the original is pressed. The sheet member 23 does not press the hand or finger in advance.

  Therefore, the hand or finger can be retreated with the back side of the document being pressed by the sheet member 23 by a method without any additional cost of selecting the elastic members 21 and 22, and the contact glass 10 is moved along with the retraction. This makes it difficult for the document to be misaligned.

  And, the amount of compression deformation of the elastic member 22 on the back side (shaft side) is ensured to be large, and the pressing on the back side is ensured, and the pressing force is also equal to or more than the front side (tip side). Therefore, the pressing state of the document does not vary or loosen even on the far side where the eyes are difficult to reach.

  Then, in the process in which the original cover 20 is rotated and descends in a free-fall manner, the shaft-side elastic member 22 is first compressed and deformed to generate a compressive stress and brake the lowering of the original cover 20. In addition, since the speed at which the sheet member 23 on the front end side comes into contact with the document or the contact glass 10 is reduced, it is difficult for the impact sound and vibration associated with the front end side collision to occur.

  Since the original pressing portion F that eliminates such floating and misalignment of the original is mounted by a method without any additional cost of selecting the elastic members 21 and 22, the original image is clearly and accurately and highly reliable. It is possible to provide an image reading apparatus G that can be read efficiently without trial and error, and has increased operational feeling and security when setting a document at low cost.

  Furthermore, by providing such an image reading apparatus G, the image forming apparatus reduces printing errors due to image reading defects, saves paper resources, and improves workability, work efficiency, operating rate, and operational feeling. Both can be improved.

1 is an external view of an image reading apparatus according to an embodiment of the present invention. It is explanatory drawing of a structure of an image reading unit. It is explanatory drawing of a document pressing state. It is explanatory drawing of the design size of an elastic member. It is explanatory drawing of the process in which a document crimping plate is rotated. It is explanatory drawing of the document holding | suppressing part of another embodiment. It is explanatory drawing of the document pressing part of another embodiment. It is explanatory drawing of a structure of the image forming apparatus carrying an image reading apparatus. FIG. 3 is an explanatory diagram of a configuration of an image reading apparatus including a document conveying device (ADF).

Explanation of symbols

A, G Image reading device B Device main body (image forming means)
1 Device body 10 Contact glass (transparent member)
11 Document 12 Reading unit (reading means)
20 Document pressure plate (support member)
21 Elastic member (elastic member on the tip side)
22 Elastic member (Axial elastic member)
23 Sheet member (contact member)
24 fulcrum (axis of rotation)
25a, 25b, 25c, 25d Elastic member (intermediate elastic member)
d Elastic member mounting surface step

Claims (10)

A contact member that presses the document placed on the transparent member on which the document is placed;
A support member that is rotatably arranged with respect to the transparent member and exerts a pressing force on the contact member;
In the document pressing device comprising: an elastic body member that elastically supports the contact member on the shaft side and the tip side of the support member,
The height of the elastic member on the shaft side and the tip side is such that a gap is secured between the contact member and the transparent member on the tip side when the contact member contacts the transparent member on the shaft side. The amount of compressive deformation of the elastic member in the process of rotating the support member and pressing the transparent member is larger on the shaft side than on the tip side. Document holding device. The elastic member has a shaft-side elastic member disposed on the shaft side, and a tip-side elastic member disposed on the tip side,
The elastic coefficient of the shaft side elastic body member in the pressed state in which the transparent member is pressed by the support member × the amount of compressive deformation is larger than the elastic coefficient of the tip side elastic body member × the amount of compressive deformation. The document pressing device according to claim 1, wherein the document pressing devices are set equal to each other.   3. The document pressing device according to claim 2, wherein a height of the shaft-side elastic member is higher than that of the tip-end elastic member.   3. The document pressing device according to claim 2, wherein a support surface of the shaft-side elastic member formed on the support member is lower than a support surface of the tip-end elastic member. The shaft-side elastic member and the tip-side elastic member are substantially equal in height in an uncompressed state,
3. The document pressing device according to claim 2, wherein the height is larger than a distance between the support member and the transparent member in a pressed state.   6. The document pressing device according to claim 2, wherein an elastic coefficient of the tip side elastic member is set larger than that of the shaft side elastic member.   The elastic modulus and the height are selected so that the pressing force is substantially equal between the lower end elastic member and the lower elastic member in the pressed state. Document holding device.   7. The document according to claim 6, wherein the elastic coefficient and the height are selected so that a pressing force under the tip side elastic body member in the pressed state is smaller than under the shaft side elastic body member. Holding device. A transparent member on which the document is placed;
A document pressing means for holding the document placed on the transparent member in a readable manner;
An image reading apparatus comprising: an image reading unit that reads an image of the document held by the document pressing unit;
9. An image reading apparatus, wherein the document pressing unit is the document pressing device according to claim 1. Image reading means for reading an image of the original;
In an image forming apparatus comprising: an image forming unit that forms the read image on a sheet;
An image forming apparatus according to claim 9, wherein the image reading unit is the image reading apparatus according to claim 9.

Images