JP2022035091A - Reading device and image forming apparatus - Google Patents

Abstract

To provide a reading device that, when an ADF is closed, reduces a speed of fall of the ADF by its own weight to suppress generation of impact sound and allows a user who wants to quickly close the ADF to perform a closing operation without discomfort, and an image forming apparatus including the reading device.SOLUTION: Movable hinges 612 are fixed to an ADF. A spiral groove 6124a formed in an inner peripheral surface of a bearing 6124 of the movable hinge and a spiral thread 6131a formed on an outer peripheral surface of a spindle 613 are screwed with each other. A clearance between the spiral thread and the spiral groove is filled with grease 615 that has thixotropy characteristics in which apparent viscosity is reduced according to increase in a shear rate.SELECTED DRAWING: Figure 7

Description

The present disclosure relates to a reading device for reading an image of a document placed on a document mounting table and an image forming device provided with the reading device.

In a scanning device such as a scanner that reads an image of a document, an automatic document transporting device (hereinafter referred to as "ADF") is placed in front of the scanning device via a shaft support mechanism such as a hinge arranged on the back side of the document mounting table of the scanning device. Some of them are shaft-supported so that the side can be opened and closed up and down.

When reading a document image without using the ADF in such a reading device, the user first opens the ADF upward, places the document on the platen glass of the document mounting table, and then closes the ADF. At this time, the bottom surface portion of the ADF functions as a document pressing member.

However, the conventional shaft support mechanism is usually designed so that when the opening angle (the angle formed by the document mounting table and the document pressing surface of the ADF) becomes smaller than a predetermined angle, the shaft is dropped and closed by the weight of the ADF. If the user releases the ADF when the angle is less than the opening angle, the ADF will fall and close as it is, and a loud impact sound may be generated between the ADF and the document mounting table, which may cause discomfort to the user. rice field.

In order to suppress the generation of such a large impact sound, for example, in Patent Document 1, an oil damper is provided on a hinge that supports the ADF, and the resistance of the oil damper reduces the falling speed when the ADF closes. Is disclosed.

Japanese Unexamined Patent Publication No. 7-120845

However, although the oil damper is certainly excellent in cushioning property, on the other hand, it has a large resistance, and when the user is in a hurry to copy a large number of documents, he / she wants to close the ADF quickly and lowers the ADF. Even if it is pressed against the oil damper, the ADF cannot be closed as quickly as expected due to the resistance of the oil damper, and there is a problem that the operability is poor.

In the above, the ADF has been described as an example of the document pressing member, but the present invention is not limited to this. For example, in an inexpensive reading device, the ADF is not attached and the plate-shaped document pressing member can be opened and closed. It is often done. Even if it is such a plate-shaped document pressing member, if the opening angle becomes smaller than a predetermined value when closing the member, if the hand is released, it will still fall and the impact sound with the document mounting table will be heard. Occurs not a little. In order to avoid such impact noise, even if an oil damper is used, deterioration of operability is unavoidable as described above.

The present disclosure has been made in view of the above circumstances, and when the document presser is closed, the falling speed due to its own weight is suppressed to suppress the generation of impact sound as much as possible, and the document presser is closed as soon as possible. It is an object of the present invention to provide a reading device capable of performing a closing operation without discomfort by a desired user and an image forming device provided with the reading device.

In order to achieve the above object, the present disclosure is a reading device for reading an image of a document placed on a document mounting table, and the document presser for pressing the document placed on the document mounting table from above is described as described above. The shaft support mechanism is provided with a shaft support mechanism that can be opened and closed with respect to the document mounting table, and a resistance force applying means that applies a resistance force to the closing direction of the document holder. The resistance force applying means is the shaft support. Of the outer circumference of the support shaft in the mechanism and the inner circumference of the bearing portion bearing the support shaft, a surface area increasing portion including a groove or a rough surface is formed on a part or all of the peripheral surface of at least one of the bearing portions, and the shear rate is increased. It is characterized in that grease having a thixotropic property whose viscosity decreases as the amount of the bearing increases is filled between the outer periphery of the support shaft and the inner circumference of the bearing portion in the range where the surface area increase portion is formed.

Further, in the surface area increasing portion, a spiral groove is formed on either the outer peripheral surface of the support shaft or the inner peripheral surface of the bearing portion, and a spiral crest screwed into the spiral groove is formed on the other side. May be.

Further, the document mounting table has a reference position for placing a document, and the spiral groove is provided so that the document retainer moves toward the previously described reference position in response to the operation of closing the document retainer. The spiral direction may be set.

Further, the grease may be any one of Na soap-based grease, Al soap-based grease, and Ca soap-based grease.

Further, the resistance force applying means applies a second moment to the document presser against the first moment by the urging force of the elastic material with respect to the first moment generated in the direction in which the document presser closes due to the action of gravity. It further has an urging mechanism to generate, and the urging mechanism keeps the second moment from the first moment until the original presser is closed from the opening reference position and the opening angle becomes a predetermined value. When the moments of both are large or equal to each other to prevent the document presser from closing due to its own weight and the opening angle of the document presser becomes a predetermined value or less, the second moment is smaller than the first moment. May be.

Further, the document retainer may be a document transfer device.

Further, the shaft support mechanism may include a plurality of hinge mechanisms arranged along the center line of the support shaft, and at least one hinge mechanism may be provided with the resistance applying means.

Further, among the plurality of hinge mechanisms, the resistance applying means may be provided in the hinge mechanism close to the position of the center of gravity of the document holder in the direction along the center line of the support shaft.

Further, the image forming apparatus of the present disclosure is characterized in that the above-mentioned reading device is provided as a reading unit for a document image, and an image is formed using the document image read by the reading device.

With the above configuration, it is possible to reduce the speed at which the original presser closes due to its own weight by utilizing the characteristics of grease, and suppress the generation of impact noise. On the other hand, when a force is applied to the document presser by a user who wants to close the document presser quickly, the viscosity decreases due to the increase in the shear rate with respect to the grease. It can be closed, the operability is improved, and the user does not feel any discomfort.

It is a perspective view which shows the whole structure of the image forming apparatus roughly. It is a perspective view which shows the state which ADF is open with respect to the document placing table of a scanner part. It is an external perspective view of a hinge part. It is a schematic side view of the hinge part for demonstrating the change of the moment caused by the urging mechanism according to the opening angle at the time of closing ADF, and (a) shows the state which ADF opened up to the upper limit angle. It is a figure, (b) shows the state which ADF opened by the lower limit angle of a free stop, and (c) is a figure which shows the state which ADF is completely closed. It is a graph which shows how the moment by the urging mechanism and the moment by the own weight of ADF change according to the opening angle of ADF. It is an exploded perspective view of the hinge part for demonstrating the connection structure of a movable hinge and a support shaft. (A) is a cross-sectional view taken along the line DD of FIG. 4 (a), and (b) is an enlarged view of a portion surrounded by a circle E of (a). It is a figure which shows how the apparent viscosity of grease changes according to a shear rate. (A) is a diagram showing the spiral direction of the spiral groove of the support shaft, and (b) is a process in which the document placed slightly away from the mounting reference position on the document mounting table is completely closed by the ADF. , Is a diagram schematically showing a state of approaching a mounting reference position.

[1] Embodiment An image forming apparatus 1 as an embodiment according to the present disclosure will be described with reference to the drawings.

(1-1) Configuration of Image Forming Device 1 FIG. 1 is a perspective view schematically showing the overall configuration of the image forming apparatus 1. In the figure, the X-axis direction corresponds to the left-right direction when the image forming apparatus 1 is viewed from the front side, and the Y-axis direction corresponds to the vertical direction. Further, the direction orthogonal to both the X-axis and the Y-axis is the Z-axis direction (depth direction).

As shown in FIG. 1, the image forming apparatus 1 is a so-called multifunction device (MFP: Multifunction Peripheral), and includes a document reading unit 100, an image forming unit 200, and a paper feeding unit 300. The document reading unit 100 (reading device) includes a scanner unit 10 and an ADF 20 (document holder) arranged above the scanner unit 10.

The image forming unit 200 forms an image on the recording sheet supplied by the feeding unit 300 by using the scan data generated by the scanner unit 10. The recording sheet on which the image is formed is ejected onto the output tray 201.

The image forming unit 200 is not limited to the electrophotographic method as long as the image can be formed on the sheet, and may be, for example, an inkjet method.

FIG. 2 is a perspective view showing a state in which the ADF 20 is open with respect to the document mounting table of the scanner unit 10.

As shown in the figure, on the upper surface 10a of the housing 12 of the scanner unit 10, a platen glass 11 (manuscript mounting table) for placing a document and reading an image and an image of the document conveyed by the ADF 20 are read. A glass window 13 for reading a document is provided for this purpose.

A carriage (not shown) on which a light source, a mirror, or the like is mounted is arranged below the platen glass 11, and an image of a document is scanned to generate image data while making the carriage (not shown) movable in the X direction.

A shaft support mechanism 60 that pivotally supports the ADF 20 so as to be able to open and close is arranged along the inner side of the upper surface 10a of the housing 12 of the scanner unit 10.

When reading a document placed on the platen glass 11, the ADF 20 is opened, the document is placed in the reference position on the platen glass 11, the ADF 20 is closed, and the pressing plate 22 arranged on the bottom thereof is closed. Move the carriage while pressing so that the document does not float, scan the document, and generate image data.

With the ADF 20 closed, the originals are transported one by one from the original bundle placed on the original tray 21 (FIG. 1) of the ADF 20, and are placed on the original reading glass window 13 of the scanner unit 10 (original). It is also possible to read the original image by passing through the scanning position), that is, the so-called sheet-through method of scanning the original. At this time, the carriage is moved directly under the document reading glass window 13.
(1-2) Configuration of Shaft Support Mechanism 60 (1-2-1) Outline As shown in FIG. 2, the shaft support mechanism 60 is composed of two hinge portions 61 and 62 (hinge mechanism), and the rotation thereof. The center of motion is arranged on a virtual rotation center axis C (center line of a support axis) parallel to the inner side of the upper surface 10a of the housing 12 of the scanner unit 10.

FIG. 3 is an external perspective view of the hinge portion 61.

As shown in the figure, the hinge portion 61 includes a fixed hinge 611, a movable hinge 612, a support shaft 613, an urging mechanism 614, and the like. Since the hinge portion 62 has the same configuration as the hinge portion 61, only the structure of the hinge portion 61 will be described below.

The fixed hinge 611 has a pair of frame members 6113 and 6114 for holding the support shaft 613 erected on the upper surface of the pedestal 6111, and a cylindrical member 6110 having a rectangular cross section and a bottom is attached below the pedestal 6111. Become.

A support shaft 613 is inserted through the through holes 6113a and 6114a (see FIG. 6) of the pair of frame members 6113 and 6114, and the movable hinge 612 is rotatably connected to the fixed hinge 611 via the support shaft 613. Will be done.

A spiral ridge is formed on the support shaft 613, and the bearing portion 6124 (see FIG. 6) having a spiral groove of the movable hinge 612 is screwed with a slight clearance, and grease is applied to the clearance. By filling, the ADF 20 is configured to gently close in a range smaller than the opening angle θ1 (FIG. 5) (hereinafter, referred to as “rotational resistance imparting mechanism”). Details will be described later.

Then, the tubular member 6110 below the pedestal 6111 fits into a square hole 121 slightly larger than the outer diameter cross section of the tubular member 6110 provided on the inner side of the upper surface 10a (FIG. 2) of the housing 12 of the scanner unit 10. The fixed hinge 611 is attached to the scanner portion 10 by being inserted and the lower surface of the pedestal 6111 abuts on the peripheral edge portion of the square hole 121 of the upper surface 10a.

As a result, the fixed hinge 611 can move in the vertical direction, and when the document placed on the platen glass 11 is a thick object such as a book, the fixed hinge 611 moves upward to the pressing plate 22 of the ADF 20. The difference in inclination from the original is reduced, and the entire original is pressed against the platen glass 11 by the pressing plate 22 as much as possible so that the original does not partially separate from the platen glass 11.

The movable hinge 612 has a central portion 6121 provided with a protruding cam 6140, and wing portions 6122 and 6123 extending from the central portion 6121 to both left and right sides, and through holes 6122a and 6123a bored in the wing portions 6122 and 6123. The ADF 20 is pivotally supported with respect to the scanner unit 10 by being screwed into a screw hole (not shown) provided on the bottom surface 20a (FIG. 2) of the ADF 20.

(1-2-2) Biasing mechanism The urging mechanism 614 has a moment (opening moment (second moment)) in the opposite direction (arrow B) with respect to the operation of urging the movable hinge 612 to close the ADF 20. The protrusion cam 6140 of the movable hinge 612, the push-up plate 6141 that abuts on the protrusion cam 6140, and the compression spring 6142 (elastic material) that urges the push-up plate 6141 upward (Y-axis direction). ). Due to the urging force of this elastic material, the urging mechanism 614 generates a second moment in the ADF 20.

4 (a) to 4 (c) are schematic side views of the hinge portion 61 for explaining the change in the moment generated by the urging mechanism 614 according to the opening angle when the ADF 20 is closed, and are the schematic side views of the hinge portion 61 for convenience. Is omitted, and only the hinge portion 61 is shown.

In the urging mechanism, the elastic material may be any material that generates urging force, and for example, a leaf spring or a torsion spring may be used to form the urging mechanism.

FIG. 4 (a) shows a state in which the ADF 20 is opened to the upper limit angle (opening reference position), FIG. 4 (b) shows a state in which the ADF 20 is closed to the open angle θ, and FIG. 4 (c) shows a state in which the ADF 20 is closed to the open angle θ. , Indicates that the ADF20 is completely closed.

As can be seen from each figure, as the opening angle decreases, the amount of the protruding cam 6140 of the movable hinge 612 pushing the push-up plate 6141 downward increases, and the repulsive force from the compression spring 6142 also changes from F1 to F3. Although it gradually increases, the length (arm length) of the perpendicular line from the central axis C of the support shaft 613 to the action line of the repulsive force gradually shortens to r1, r2, and r3, so that the ADF20 is opened. The magnitudes of the acting moments M1, M2, and M3 (repulsive force × arm length) tend to increase once and then decrease.

On the other hand, as described above, since the ADF 20 is pivotally supported with respect to the scanner unit 10 so as to be openable and closable, the moment acting in the direction of closing the movable hinge 612 due to the weight of the ADF 20 (closing moment (first moment)). ) Acts on the movable hinge 612.

FIG. 5 is a diagram showing changes in the opening moment due to the urging mechanism 614 and the closing moment due to the weight of the ADF 20 according to the change in the opening angle θ.

The horizontal axis indicates the magnitude of the open angle θ, and the vertical axis indicates the magnitude of the moment acting on the ADF 20.

In the figure, the solid line G1 shows the change in the opening moment generated in the direction of opening the ADF 20 by the urging mechanism 614. As the opening angle θ becomes larger, the opening moment increases, becomes maximum at the opening angle θ2, and then decreases.

The shape of the solid line G1 including the value of the opening angle θ2 at which the opening moment is maximized is determined by the shape of the protruding cam 6140, the spring coefficient of the compression spring 6142, and the like.

On the other hand, the closing moment generated by the weight of the ADF20 is mg * Lcosθ when the distance from the center of gravity C of the support shaft 613 to the center of gravity of the ADF20 is L, the mass is m, and the gravitational acceleration is g. It changes as shown by the broken line G2 in 5.

The opening moment and the closing moment are in opposite directions, but for convenience of explanation, only the magnitudes of these moments are shown in the figure.

As shown in FIG. 5, in the closed state, the closing moment due to the own weight of the ADF20 shown by the broken line is larger than the opening moment by the urging mechanism 614 shown by the solid line, and the opening angle is θ1 (for example, 15 °). ~ 20 °), these moments are equal.

When the opening angle is larger than θ1, the moment by the urging mechanism 614 is slightly larger than the closing moment due to the weight of the ADF20. The ADF 20 is in a so-called free stop state in which the ADF 20 stands still without rotating while maintaining the corner. As a result, the urging mechanism 614 makes the second moment larger than the first moment or both moments until the ADF 20 is closed from the opening reference position and the opening angle reaches a predetermined value (θ1). Is equalized to prevent the ADF 20 from closing due to its own weight, and when the opening angle of the ADF 20 becomes a predetermined value (θ1) or less, the second moment becomes smaller than the first moment.

In the free stop state, although the opening moment by the urging mechanism 614 is larger than the closing moment by the weight of the ADF 20, the hinge portion 61 does not rotate in the opening direction indicated by the arrow B. , 62 because of the mechanical static friction force.

As shown in FIG. 5, as the opening angle of the ADF 20 moves from the state of θ1 to the closed state, the difference between the moment due to the own weight of the ADF 20 and the moment due to the urging mechanism 614 increases, so that the ADF 20 has its own weight. When falling, the falling speed cannot be sufficiently reduced, and when the ADF 20 is closed, a loud impact sound is generated between the scanner unit 10 and the scanner unit 10, which makes the user feel uncomfortable.

As described above, in the prior art (Patent Document 1), in order to suppress a loud impact sound, an oil damper is provided in the hinge portion, and the drop speed of the ADF 20 is reduced by the resistance of the oil damper. The power of the oil damper to counteract the problem is so great that the ADF20 cannot be closed quickly, which has been a stress for the user.

In the present embodiment, the connecting structure of the movable hinge 612 and the support shaft 613 is devised to give a resistance according to the opening / closing speed of the ADF 20 so that the user can close the ADF 20 according to the intention. ..
(1-2-3) Connection Structure of Movable Hinge 612 and Support Shaft 613 FIG. 6 is an exploded perspective view of a hinge portion 61 for explaining a connection structure (rotational resistance imparting mechanism) between the movable hinge 612 and the support shaft 613. Is. The push-up plate 6141 and the compression spring 6142 in the urging mechanism 614 are not shown.

As shown in the figure, the support shaft 613 has an axial central portion 6131 in which a spiral crest 6131a (surface area increasing portion) is formed on the outer peripheral surface of a shaft member having a circular cross section, and a shaft having a smaller diameter than the axial central portion 6131. It has a directional tip 6132.

The diameter of the through hole 6113a of the frame member 6113 of the fixed hinge 611 is slightly larger than the diameter of the axial central portion 6131 of the support shaft 613, and the through hole 6114a of the frame member 6114 is coaxial with the through hole 6113a. The diameter is slightly larger than the diameter of the axial tip portion 6132 of the support shaft 613.

A bearing portion 6124 sandwiched between the through hole 6113a of the frame member 6113 of the fixed hinge 611 and the through hole 6114a of the frame member 6114 is formed in the central portion 6121 of the movable hinge 612, and the inner circumference of the bearing portion 6124 is formed. A spiral groove 6124a (surface area increasing portion) screwed with the spiral ridge 6131a of the support shaft 613 is formed on the surface.

The support shaft 613 and the movable hinge 612 are connected as follows.

First, the movable hinge 612 is arranged so that the bearing portion 6124 of the movable hinge 612 and the through holes 6113a and 6114a of the frame members 6113 and 6114 of the fixed hinge 611 are coaxial with each other, and the axial tip portion 6132 of the support shaft 613 is provided. , Pass through the through hole 6113a of the frame member 6113 of the fixed hinge 611.

After that, when the support shaft 613 is further advanced, the edge 6131b of the spiral ridge 6131a of the support shaft 613 comes into contact with the edge 6124b of the bearing portion 6124 of the movable hinge 612.

From this state, the support shaft 613 is screwed so that the spiral ridge 6131a and the spiral groove 6124a are screwed together. Here, the spiral direction of the spiral ridge 6131a and the spiral groove 6124a is so-called left-handed, which is screwed into the bearing portion 6124 when the support shaft 613 is turned counterclockwise (FIG. 9A). When the support shaft 613 is screwed in, the axial tip portion 6132 passes through the through hole 6114a of the frame member 6114 of the fixed hinge 611, and the circumferential groove portion 6133a formed in the axial tip portion 6132 passes through the through hole 6114a. The screwing of the support shaft 613 is completed at a position where the D-cut surface 6132a is formed on the outer peripheral surface of the axial tip portion 6132 so as to face upward.

Next, the E-ring 6134 is fitted into the protruding groove 6133a, and the regulatory member 6133 having the through hole 6133a matching the D-cut shape of the axial tip 6132 is fitted into the axial tip 6132 to fit the E-ring 6134. In the sandwiched state, the regulation member 6133 and the frame member 6114 of the fixing hinge 611 are fixed by screwing.

The E-ring 6134 and the restricting member 6133 restrict the axial movement and rotation of the support shaft 613 around the shaft.

In this way, the movable hinge 612 and the support shaft 613 are connected via the spiral groove 6124a and the spiral ridge 6131a, and the movable hinge 612 rotates around the support shaft 613 along the spiral ridge 6131a. Can be done. As a result, the support shaft 613 is pivotally supported by the bearing portion 6124.

7 (a) is a cross-sectional view taken along the line DD of FIG. 4 (a), and FIG. 7 (b) is an enlarged view of a portion surrounded by the circle E of FIG. 7 (a).

As shown in FIG. 7B, the clearance between the spiral ridge 6131a and the spiral groove 6124a is filled with grease 615. The grease 615 is filled in the entire axial direction of the spiral ridge 6131a and the spiral groove 6124a, but is not limited to this, and may be filled in a part of the spiral ridge 6131a and the spiral groove 6124a in the axial direction. ..

As shown in FIG. 8, the grease 615 has a so-called thixotropic property in which the apparent viscosity (viscosity) decreases as the shear rate increases, and for example, Na soap-based grease, Al soap-based grease, or Al soap-based grease, or , Ca soap-based grease. The film thickness t of the grease 615 shown in FIG. 7B corresponds to the size of the gap between the spiral ridge 6131a and the spiral groove 6124a, and is preferably in the range of 0.5 mm to 2 mm.

As described above, since the grease 615 is filled between the outer circumference of the support shaft 613 and the inner circumference of the bearing portion 6124 in the range where the surface area increase portion is formed, when the movable hinge 612 rotates around the support shaft 613. , A force (shearing force) in the rotation direction (spiral direction) of the movable hinge 612 is applied to the grease 615 filled in the clearance between the spiral ridge 6131a and the spiral groove 6124a.

Further, by forming the outer circumference of the axial center portion 6131 of the support shaft 613 and the inner circumference of the bearing portion 6124 into a spiral shape as described above, the surface area of the outer circumference of the axial center portion 6131 and the inner circumference of the bearing portion 6124 can be reduced. The contact area between the grease 615 and the spiral groove 6124a and the contact area between the grease 615 and the spiral ridge 6131a are increased. As a result, the force that the grease 615 receives from the spiral groove 6124a and the spiral ridge 6131a can be increased, and the grease 615 is effectively sheared.

When the ADF 20 is closed, when the ADF 20 begins to fall due to its own weight, the shear rate of the grease 615 is still low, and due to the thixotropy characteristics of the grease 615 described above, the viscosity of the grease 615 is also high, so that the viscosity is high. By imparting a corresponding resistance, the falling speed of the ADF 20 can be reduced and the increase in the shearing speed of the grease 615 can be suppressed. As a result, the highly viscous state of the grease 615 is maintained until the ADF 20 is closed, and the impact sound between the grease 615 and the scanner unit 10 when the ADF 20 is closed can be suppressed.

On the other hand, when a user who wants to close the ADF 20 quickly applies a large downward force to the ADF 20, the shear rate of the grease 615 increases and the viscosity of the grease 615 decreases, so that the applied resistance becomes small. The ADF 20 can be closed smoothly so as to follow the operation of pushing down the ADF 20 by the user.

The closing operation of the ADF 20 according to the user's intention can reduce the stress of the user.
(1-3) Reference Positioning of Manuscript FIG. 9A is a diagram showing the spiral direction of the spiral ridge 6131a of the support shaft 613.

As described above, the spiral direction of the spiral ridge 6131a of the support shaft 613 is left-handed, and similarly, the direction of the spiral groove 6124a of the movable hinge 612 is left-handed. Therefore, when the movable hinge 612 rotates in the closing direction, the movable hinge 612 moves in the direction indicated by the arrow F shown in FIG. 7A.

In FIG. 2, the platen glass 11 is arranged at a position one step lower than the upper surface 10a of the housing 12 of the scanner unit 10, and when the original is placed on the platen glass 11, the placement reference position on the reference line 11a The tip of the original can be aligned with the step 11b as a platen.

FIG. 9B is a diagram showing a state in which the tip 71 of the document 70 is displaced from the step 11b. When the tip 71 of the document 70 is set in line with the platen glass 11, the document may be slightly bent by the pressure of the user's hand pressing the tip 71 of the document 70 against the step 11b. Therefore, at the moment when the setting of the original 70 is completed and the user releases the hand from the original 70, the restoring force due to the waist of the original trying to eliminate the bending and return to the original straight posture acts, and the entire original is stepped. Moving to the left from 11b, the tip 71 of the document 70 may be slightly displaced from 11b, as in the deviation G in FIG. 9B.

The pressing plate 22 (FIG. 2) of the ADF 20 that presses the original 70 after the original 70 is placed on the platen glass 11 is formed by sandwiching an elastic material such as a soft sponge in the thickness direction, and the pressing plate 22 is formed. Since the original is pressed by the elastic restoring force when it is compressed and deformed in the thickness direction, it is configured to come into contact with the original 70 before the ADF 20 is completely closed.

As described above, since the movable hinge 612 moves in the direction indicated by the arrow F when it is closed, the pressing plate 22 also moves in the direction indicated by the arrow F, that is, toward the step 11b.

Therefore, the pressing plate 22 moves the document 70 toward the step 11b after the document 70 comes into contact with the document 70 until the ADF 20 is completely closed. This amount of movement is determined by the pitch of the spirals of the spiral ridge 6131a and the spiral groove 6124a and the opening angle from the contact of the pressing plate 22 with the document 70 until the ADF 20 is completely closed.

By moving the document 70 toward the step 11b, the deviation G between the tip 71 of the document 70 and the step 11b can be reduced, whereby the image of the document and the recording sheet obtained by copying the image can be reduced. Positional deviation from the image in the X-axis direction can be reduced, and a better copy image can be obtained. Further, even when the set document is skewed, the skew can be reduced by contact with the step 11b.

The spiral direction of the spiral ridge 6131a of the support shaft 613 and the spiral groove 6124a of the movable hinge 612 is not limited to left-handed winding. In some cases, the original 70 can be moved to the mounting reference position by winding the spiral direction to the right.

Further, in the above, the configuration example in which the step 11b is the mounting reference position has been described, but the mounting reference position is not limited to this, and the document should be mounted when the document is mounted on the platen glass 11. Any position may be used as long as the position can be known. For example, a positioning sticker as a mark may be attached on the platen glass 11, and the positioning sticker may be used as the mounting reference position.

In this case, when the user sets the document on the platen glass 11, the tip 71 of the document 70 is set while being close to the positioning sticker. At this time, the document is set so that the positioning sticker is not hidden by the tip 71 of the document 70. In many cases, the tip 71 of the 70 is set at a position slightly distant from the mounting reference position.

Therefore, even when the positioning sticker is set as the mounting reference position, the deviation between the tip 71 of the document 70 and the mounting reference position should be reduced as in the case where the step is set as the mounting reference position as described above. Can be done.
[2] Modifications Although the above description has been made based on the embodiments, it is needless to say that the configuration is not limited to the above, and the following modifications can be considered.

(2-1) In the above embodiment, a configuration example in which the free stop state is realized by the opening moment by the urging mechanism 614 has been described, but in some cases, the viscosity of the grease 615 is used without using the compression spring 6142. It is also possible to take a configuration that realizes a free stop state by the resistance.

It is considered that the viscosity of the grease is high and the grease is close to a solid state when no shearing force is applied to the grease. By increasing the contact area with the grease and increasing the static frictional force with the grease, it is possible to generate a force that opposes the moment due to the weight of the ADF 20.

Further, when the opening angle of the ADF 20 is θ1, a grease having a viscosity that becomes a free stop and the ADF 20 gently closes by its own weight at an angle smaller than θ 1 may be selected according to the mass of the ADF 20. ..

The increase in the contact area between the spiral ridge and the spiral groove and the grease is made by, for example, increasing the diameter of the support shaft or increasing the length of the portion where the spiral groove of the support shaft is formed. This can be achieved by increasing the surface area between the peak and the spiral groove and increasing the amount of grease to be filled.

(2-2) In the above embodiment, the outer circumference of the axially central portion 6131 of the support shaft 613 and the inner circumference of the bearing portion 6124 are formed into a spiral shape as an example of the uneven surface (surface area increasing portion) and greased 615. Although the configuration example in which the contact area is increased and the grease 615 is effectively sheared has been described, the present invention is not limited to this.

For example, it is possible to increase the contact area with the grease 615 by making at least one of the outer circumference of the central portion in the axial direction of the support shaft and the inner circumference of the bearing portion a rough surface. By making unevenness on the rough surface in this way, the convex portion can exert a shearing force on the grease when the movable hinge is rotated, and the grease can exert a rotational resistance on the convex portion when the movable hinge is stopped. The roughness of the rough surface required to mitigate the impact sound can be obtained by experiments or the like.

Further, in the above embodiment, in order to increase the contact area, a configuration example in which both the outer circumference of the axial center portion 6131 of the support shaft 613 and the inner circumference of the bearing portion 6124 are formed into a spiral shape has been described. In some cases, a groove such as a spline groove may be formed on at least one of the outer circumference of the axially central portion 6131 of the support shaft 613 and the inner circumference of the bearing portion 6124. This is because the contact area with the applied grease increases to some extent, and rotational resistance due to the grease can be generated.

Further, in the above embodiment, the configuration example in which the support shaft 613 having the spiral ridge 6131a formed on the outer peripheral surface is fixed to the fixed hinge 611 has been described, but the present invention is not limited to this, and the support shaft is attached to the movable hinge. It can also be fixed. In this case, the fixed hinge is provided with a bearing portion having a spiral groove formed on the inner peripheral surface, so that the movable hinge can be attached to the fixed hinge via the spiral groove on the fixed hinge side and the spiral crest on the movable hinge side. It can be configured to be rotatable.

(2-3) In the above embodiment, the ADF 20 is also used as the document retainer, but the ADF 20 is optional so that the plate-shaped document retainer can be opened and closed with respect to the document mounting table by the shaft support mechanism. You may.

(2-4) In the above embodiment, a configuration example in which the hinge portion 61 and the hinge portion 62 have the same configuration has been described, but the present invention is not limited to this, and when there are a plurality of hinge portions, at least one hinge portion can be used. The above-mentioned urging mechanism and rotational resistance applying mechanism (both of which have a function of applying a force against the closing moment due to the weight of the ADF 20) may be provided (generally referred to as "resistance applying means"). In this case, if the center of gravity of the ADF 20 is biased toward the internal feeding roller, the transport roller, and the portion where the drive motor for driving these is arranged, resistance is applied to at least the hinge portion closest to the center of gravity. It is desirable to provide means.

When a plate-shaped document retainer is used as in (2-3) above, its weight is small, so that the urging mechanism can be omitted in all hinge portions, and rotational resistance is imparted. In some cases, only the mechanism is sufficient.

(2-5) In the above embodiment, a configuration example in which the support shaft 613 having the spiral ridge 6131a formed on the outer peripheral surface is fixed to the fixed hinge 611 has been described, but the present invention is not limited to this, and the support shaft is not limited to this. It can also be fixed to a movable hinge. In this case, the fixed hinge is provided with a bearing portion having a spiral groove formed on the inner peripheral surface, so that the movable hinge can be attached to the fixed hinge via the spiral groove on the fixed hinge side and the spiral crest on the movable hinge side. It can be configured to be rotatable.

Further, in the above embodiment, as shown in FIG. 7A, a spiral mountain is formed in the entire axial direction of the axial central portion 6131 of the support shaft 613, but the present invention is not limited to this. It suffices if the same smooth opening / closing operation of the ADF 20 can be realized, and for example, a spiral mountain may be provided in a part of the axial central portion 6131 of the support shaft 613, such as only the central portion. The same applies to the spiral groove of the bearing portion 6124, and the same applies to the rough surface and the spline groove described above.

≪Supplement≫
The reading device and the image forming apparatus according to the present disclosure have been described above based on the embodiments and modifications, but the present disclosure is not limited to the above embodiments and modifications. By arbitrarily combining the components and functions in the embodiment and the modification to the extent obtained by applying various modifications to the above embodiment and the modification that a person skilled in the art can think of, and within the range not deviating from the purpose of the present disclosure. The realized forms are also included in the present disclosure.

10 Scanner unit 11 Platen glass (manuscript mounting table)
20 Automatic document carrier (document retainer)
22 Press plate 60 Shaft support mechanism 61, 62 Hinge part (hinge mechanism)
100 Document reader (reading device)
611 Fixed hinge 612 Movable hinge 613 Support shaft 614 Bounce mechanism 615 Grease 6124 Bearing part 6124a Spiral groove 6131a Spiral crest 6141 Push-up plate 6142 Compression spring

Claims (9)

A reading device that reads an image of a document placed on a document mounting table.
A shaft support mechanism that supports the document holder, which presses the document placed on the document table from above, so that it can be opened and closed with respect to the document table.
A resistance applying means for applying resistance to the closing direction of the document holder, and
Equipped with
The resistance imparting means is
A surface area increasing portion including a groove or a rough surface is formed on a part or all of the outer peripheral surface of the support shaft in the shaft support mechanism and the inner circumference of the bearing portion bearing the support shaft on at least one peripheral surface. , The grease having a thixotropic property whose viscosity decreases as the shear rate increases is filled between the outer periphery of the support shaft and the inner circumference of the bearing portion in the range where the surface area increase portion is formed. Reading device. The surface area increase portion is
1. The reader according to. The document mounting table has a reference position for placing a document, and the spiral direction of the spiral groove is such that the document presser moves toward the previously described reference position in response to the closing operation of the document retainer. 2. The reading device according to claim 2, wherein is set. The reading device according to any one of claims 1 to 3, wherein the grease is any one of Na soap-based grease, Al soap-based grease, and Ca soap-based grease. The resistance imparting means is
Further, the original material presser has an urging mechanism that generates a second moment against the first moment by the urging force of the elastic material with respect to the first moment generated in the closing direction by the action of gravity. death,
The urging mechanism makes the second moment larger than the first moment or equalizes both moments until the original presser is closed from the opening reference position and the opening angle reaches a predetermined value. 1 to 4, wherein the second moment is smaller than the first moment when the document presser is prevented from closing due to its own weight and the opening angle of the document presser becomes a predetermined value or less. The reader according to any one of the above items. The reading device according to any one of claims 1 to 5, wherein the document presser is a document transporting device. The shaft support mechanism includes a plurality of hinge mechanisms arranged along the center line of the support shaft, and the resistance applying means is provided in at least one hinge mechanism. The reading device according to any one of 1 to 6. 7. Among the plurality of hinge mechanisms, claim 7 is characterized in that the resistance applying means is provided in the hinge mechanism close to the position of the center of gravity of the document holder in the direction along the center line of the support shaft. The reader according to. An image forming apparatus comprising the reading device according to any one of claims 1 to 8 as a reading unit for an original image, and forming an image using the original image read by the reading device.

Images