JP7484225B2 - Image reading device and image forming device - Google Patents

Description

This invention relates to an image reading device and an image forming device.

Conventionally, technology related to image reading devices has already been proposed, for example, as disclosed in Patent Document 1.

Patent Document 1 discloses a device that includes a glass platform on which a sheet is placed, a sheet pressing unit that can be opened and closed freely and presses the sheet placed on the glass platform from above, an image reading unit that reads an image of the sheet while the sheet is pressed from above by the sheet pressing unit, an electric opening/closing unit that assists manual opening and closing of the sheet pressing unit, a speed changing unit that changes the opening/closing speed of the sheet pressing unit by the electric opening/closing unit in response to an external force applied to the sheet pressing unit when the sheet pressing unit is manually opened or closed, an opening/closing angle detection unit that detects the opening/closing angle of the sheet pressing unit, and an opening/closing speed setting unit that determines, based on a detection signal from the opening/closing angle detection unit, whether the sheet pressing unit is in a first region where the opening/closing speed is changed in response to an external force, a second region immediately before the sheet pressing unit is completely closed, or a third region immediately before the sheet pressing unit is completely opened, and changes the opening/closing speed in response to the external force when it is determined that the sheet pressing unit is in the first region, and sets the opening/closing speed to a preset opening/closing speed regardless of the external force when it is determined that the sheet pressing unit has moved to the second or third region.

JP 2008-191197 A

The object of this invention is to provide an image reading device and an image forming device that can reduce the operating force required to open the document pressing means without compromising operability, compared to when the document pressing means is opened and closed over the entire opening and closing angle range.

The present invention described in claim 1 is a document pressing means that is attached to the device body so as to be openable and closable, and presses down a document;
an opening force application means for applying a driving force of a driving source to the document pressing means as an opening force only temporarily when the document pressing means is opened;
The image reading device includes:

The invention described in claim 2 is a detection means for detecting opening and closing of the document pressing means;
a driving means for driving the driving source for a fixed period of time when the detection means detects that the document pressing means is in an open state;
The image reading device according to claim 1, further comprising:

The invention described in claim 3 is an image reading device described in claim 2, wherein the driving means drives the driving source from the time the detection means detects the open state of the document holding means until the open angle of the document holding means becomes a predetermined angle.

The invention described in claim 4 further comprises a counterbalance for applying a force in an opening direction to the document pressing means,
3. The image reading device according to claim 2, wherein the driving means drives the driving source until the rotational moment required to open the document holding means becomes equal to or less than the rotational moment due to a force in the opening direction of the counterbalance, and stops the driving source after the rotational moment becomes equal to or less than the rotational moment .

The invention described in claim 5 is the image reading apparatus described in claim 2, wherein the drive means rotates in a reverse direction after the temporary drive, thereby releasing the force applied to the opening force applying means.

The invention described in claim 6 is the image reading device described in claim 1, in which the opening force application means applies an opening force to the front side of the fulcrum that supports the document pressing means so that it can be opened and closed, and to the rear side of the reading position of the document.

The invention described in claim 7 is the image reading device described in claim 5, in which the opening force application means applies a push-up force to the document pressing means.

The invention described in claim 8 is the image reading device described in claim 1, which is provided with an absorbing means that absorbs the excessive force when an excessive force exceeding a predetermined value acts on the opening force applying means.

The invention described in claim 9 is the image reading device described in claim 8, in which the absorbing means is made of an elastic member that absorbs the excessive force by elastically deforming when the excessive force acts on the opening force application means.

According to a tenth aspect of the present invention, the opening force application means includes a link mechanism in which an upper end of the link mechanism rotates around a fulcrum located in the middle of the link mechanism so as to push up the document pressing means by moving a lower end of the link mechanism in a horizontal direction;
a wire member that moves a lower end of the link mechanism by a driving force of the driving source;
2. The image reading apparatus according to claim 1, further comprising:

In the invention described in claim 11, the link mechanism includes a first link member having an upper end that abuts against the document pressing means and a lower end that is supported so as to be movable along a horizontal direction;
a second link member having an upper end rotatably connected to the middle of the first link member and a lower end supported so as to be movable along a horizontal direction;
11. The image reading device according to claim 10, further comprising:

The invention described in claim 12 further includes image reading means for reading an image of the document conveyed to a reading position by the document pressing means,
2. The image reading apparatus according to claim 1, wherein the driving source is a driving source for the image reading means.

The invention described in claim 13 is the image reading apparatus described in claim 12, wherein when the document pressing means is open, power supply to the drive source is cut off.

The present invention as set forth in claim 14 further comprises an image reading means for reading an image of the document;
an image forming means for forming an image of the document read by the image reading means;
Equipped with
The image forming apparatus uses the image reading device according to any one of claims 1 to 13 as the image reading means.

According to the invention described in claim 1, it is possible to provide an image reading device and an image forming device that can reduce the operating force required to open the document pressing means without compromising operability, compared to when the document pressing means is opened and closed over the entire opening and closing angle range.

According to the invention described in claim 2, it is possible to deal with the case where the door is opened only to the minimum extent necessary to allow operation and then the user starts to close the door, as opposed to when the drive source is driven continuously.

According to the invention described in claim 3, the opening and closing force can be reliably applied until the document pressing means opens, compared to a case in which the drive source is not driven until the opening angle of the document pressing means reaches a predetermined angle.

According to the invention described in claim 4, the drive means can reliably apply an opening/closing force until the rotational moment required to open the document pressing means becomes equal to or less than the rotational moment due to the force in the opening direction of the counterbalance, compared to a case in which the drive source is not driven until the rotational moment required to open the document pressing means becomes equal to or less than the rotational moment due to the force in the opening direction of the counterbalance.

According to the invention described in claim 5, the driving means can avoid excessive force being applied to the opening force application means even when the operator performs an operation to close the document pressing means immediately after performing an operation to open the document pressing means, compared to when the driving means continues to apply force to the opening force application means even after performing a temporary drive.

According to the invention described in claim 6, the opening force of the opening force applying means can be applied to the document pressing means more efficiently than when the opening force applying means applies an opening force to the rear side of the fulcrum that supports the document pressing means so that it can be opened and closed.

According to the invention described in claim 7, the opening force application means can have a simpler configuration than when a rotational force is applied directly to the document pressing means.

According to the invention described in claim 8, it is possible to avoid malfunctions when excessive force acts on the opening force application means, compared to a case in which no absorption means for absorbing excessive force is provided.

According to the invention described in claim 9, the structure of the opening force application means can be simplified compared to when the absorbing means is not made of an elastic member.

According to the invention described in claim 10, the structure of the opening force exerting means can be simplified compared to a case where the opening force exerting means is not configured as a link mechanism.

According to the invention described in claim 11, the height of the link mechanism can be reduced compared to a case in which the link mechanism is not composed of a first link member and a second link member.

According to the invention described in claim 12, the number of parts can be reduced compared to a case where the driving source of the image reading means is not used as the driving source.

According to the invention described in claim 13, the document pressing means can be prevented from malfunctioning when the document pressing means is opened, compared to a case in which power supply to the drive source is not cut off when the document pressing means is open.

According to the invention described in claim 14, it is possible to provide an image forming apparatus that can reduce the operating force required to open the document pressing means without compromising operability, compared to a case in which the image reading device described in any one of claims 1 to 13 is not used as the image reading means.

1 is an overall configuration diagram showing an image forming apparatus to which an image reading device according to a first embodiment of the present invention is applied; 1 is a configuration diagram showing an image reading device according to a first embodiment of the present invention; 1 is a configuration diagram showing an automatic document feeder according to a first embodiment of the present invention; 1 is a perspective configuration diagram showing a state in which an automatic document feeder of an image forming apparatus according to a first embodiment of the present invention is open; 1 is a configuration diagram showing an automatic document feeder according to a first embodiment of the present invention; 4 is a graph showing the rotation moment required to open the automatic document feeder according to the first embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a reed switch. 1 is a configuration diagram showing an automatic document feeder according to a first embodiment of the present invention in a closed state; 1 is a configuration diagram showing a main part of an automatic document feeder according to a first embodiment of the present invention; FIG. 1 is a configuration diagram showing a main part of an automatic document feeder according to a first embodiment of the present invention; FIG. FIG. 2 is a block diagram showing a control device. 1 is a configuration diagram showing a main part of an automatic document feeder according to a first embodiment of the present invention; FIG. 11 is a configuration diagram showing a main part of an image reading device according to a second embodiment of the present invention. FIG. 11 is a configuration diagram showing a main part of an image reading device according to a second embodiment of the present invention.

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

[Embodiment 1]
FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus to which an image reading apparatus according to a first embodiment of the present invention is applied.

<Overall Configuration of Image Forming Apparatus>
The image forming apparatus 1 according to the first embodiment is configured as, for example, a color copying machine. The image forming apparatus 1 includes an image reading device 3 as an example of an image reading means for reading an image of an original 6, and an image forming section 2 as an example of an image forming means for forming an image on a recording medium based on image data read by the image reading device 3. The image reading device 3 is disposed above an apparatus main body 1a that houses the image forming section 2, in a state supported by a support section 4. A space is formed between the image reading device 3 and the apparatus main body 1a for discharging the recording medium on which an image has been formed.

As shown in FIG. 1, the image reading device 3 is provided with a control panel 66 as an operation unit for operating the image forming device 1 and the image reading device 3, on the upper part of the front wall 311 located on the front side of the housing 31. The control panel 66 also serves as a display unit that displays operation menus, warnings, messages, etc. to the operator (user), and has a touch panel 67 that accepts various settings for the displayed operation menu, and multiple operation buttons 68.

The image forming section 2 includes a plurality of image forming devices 10 that form toner images developed with toner constituting a developer, an intermediate transfer device 20 that holds the toner images formed by each image forming device 10 and transports them to a secondary transfer position where they are finally secondarily transferred onto a recording sheet 5 as an example of a recording medium, a paper feed device 50 that stores and transports the required recording sheet 5 to be supplied to the secondary transfer position of the intermediate transfer device 20, and a fixing device 40 that fixes the toner image on the recording sheet 5 that has been secondarily transferred by the intermediate transfer device 20. The device main body 1a is formed of a support structure member, an exterior cover, etc. The image forming section 2 is not limited to an electrophotographic system, and may be one that employs other systems such as an inkjet system, a thermal head system, or a lithography system as long as it is capable of forming an image on a recording medium.

The paper feeder 50 is disposed so as to be located below the imaging device 10. This paper feeder 50 is mainly composed of a plurality (or a single) of paper containers _51.sub.1 to _51.sub.4 that contain stacked recording paper 5 of desired sizes, types, etc., and feeders 52, 53 that feed the recording paper 5 one sheet at a time from the paper containers _51.sub.1 to _51.sub.4 . The paper container 51 is attached, for example, so as to be able to be pulled out from the front side (the side that an operator faces during operation) of the device main body 1a.

Between the paper feed device 50 and the intermediate transfer device 20, there is provided a paper feed transport path 56 consisting of multiple paper transport rollers 54, 55 and a transport guide (not shown) that transport the recording paper 5 sent out from the paper feed device 50 to the secondary transfer position. The paper transport roller 55, which is located just before the secondary transfer position in the paper feed transport path 56, is configured as, for example, a roller (registration roller) that adjusts the transport timing of the recording paper 5. Furthermore, downstream of the fixing device 40 in the paper transport direction, there are transport rollers 58 and discharge rollers 59 that discharge the recording paper 5 into a discharge storage section 57 provided at the top of the device main body 1a.

The image forming device 1 further includes a duplex unit 60 for forming images on both sides of the recording paper 5. When the duplex unit 60 transports the recording paper 5 with an image formed on one side to the discharge storage section 57 by the discharge roller 59, the discharge roller 59 is rotated in the reverse direction while holding the trailing end of the recording paper 5, thereby introducing the recording paper 5 through a switching gate 61. The duplex unit 60 has a duplex transport path 65 consisting of a plurality of transport rollers 62-64 that transport the introduced recording paper 5 in an inverted state, and a transport guide (not shown).

The recording paper 5 on which the image has been formed is discharged by the transport rollers 58 and the discharge rollers 59, for example, to the discharge storage section 57 located at the top of the device main body 1a.

When forming an image on both sides of the recording paper 5, the recording paper 5 with an image formed on one side is transported to the discharge storage section 57 by the discharge roller 59, and the rotation direction of the discharge roller 59 is switched to the reverse direction while the discharge roller 59 is holding the rear end of the recording paper 5. The recording paper 5 transported in the reverse direction by the discharge roller 59 has its transport direction switched to the double-sided unit 60 side by the switch gate 61. The recording paper 5 is then transported to the paper transport roller 55 in a reversed state via the double-sided transport path 65 equipped with transport rollers 62 to 64, etc. The paper transport roller 55 sends the recording paper 5 to the secondary transfer position in accordance with the transfer timing and supplies it. The toner image is secondarily transferred from the intermediate transfer belt 21 to the back side (second side) of the recording paper 5, the fixing process is performed by the fixing device 40, and the recording paper 5 is discharged by the discharge roller 59 with the second side facing down to the discharge storage section 57 installed at the top of the device main body 1a.

<Configuration of Image Reading Device>
FIG. 2 is a schematic diagram showing the configuration of the image reading device according to the first embodiment.

The image reading device 3 is roughly divided into a housing 31 as an example of the device body of the image reading device 3 with a document reading surface (support surface) formed on the upper end surface, and an automatic document feeder (DADF: Duplex Automatic Document Feeder) 33 as an example of a document holding means that is openably and closably attached to the housing 31 and holds down the document 6. The automatic document feeder 33 is provided with a document holding cover 32. Note that the document holding means is not limited to the automatic document feeder 33, and may be composed of the document holding cover 32 itself without the automatic document feeder 33.

When the automatic document feeder 33 is closed relative to the image reading device 3, the automatic document feeder 33 separates the originals 6 set (placed) on the automatic document feeder 33 and transports them one by one to the reading position. To do this, the automatic document feeder 33 is provided with a plurality of transport members for transporting the originals 6 and a drive motor as a drive source for driving the plurality of transport members. For this reason, the automatic document feeder 33 tends to be heavy (increased in weight) overall. Note that the drive source for driving the transport members of the automatic document feeder 33 is energized when the automatic document feeder 33 is closed, but is de-energized when the automatic document feeder 33 begins to open so that the transport members are not driven when the automatic document feeder 33 is open.

The image reading device 3 is configured to be automatically switchable between a first reading mode in which the image of the original 6 is read while the automatic document feeder 33 automatically transports the original 6 one sheet at a time, and a second reading mode in which the image of the original 6 placed on the document table 83 (described later) and held down by the document holding cover 32 is read, depending on the operation of the operator. Figure 2 shows the state of each component when the original is read in the first reading mode.

The automatic document feeder 33 has a document feed mechanism that includes a document storage section 70 as an example of a sheet stacking section that can store multiple documents 6 with the reading surface (first surface) facing up, a nudger roller 71 as an example of a sending means that sends out the documents 6 from the document storage section 70, a feed roller 72 as an example of a sending means that separates and supplies the documents 6 sent out by the nudger roller 71 one by one, a pressure pad 72a that is pressed against the feed roller 72 to separate the documents 6 one by one, a first conveying roller 73 that conveys the documents 6 to the reading position, conveying rollers 74 and 75 that convey the documents 6 conveyed by the first conveying roller 73 so that they pass through the reading position, and a discharge roller 77 as an example of a second conveying roller that discharges the documents 6 to the discharge storage section 76. The nudger roller 71, feed roller 72, conveying rollers 73 to 75, and discharge roller 77 are driven when the documents 6 are read. The first transport roller 73 is a registration roller that adjusts the timing of transporting the document 6 to the reading position. Note that in this embodiment 1, although it is not specifically described as a pair of rollers, the terms transport roller and discharge roller include a pair of rollers.

The first transport roller 73 also functions as a correction means for mechanically correcting the inclination of the document 6 with respect to the transport direction (hereinafter referred to as "skew correction") and correcting the edge of the document 6 in the same direction as the transport direction. As shown in FIG. 2, the transport roller 73b, which is a drive roller among the first transport rollers 73, is driven by a drive motor or the like as a drive means so as to rotate in the forward rotation direction Ra in the figure at a predetermined timing from a stopped state. The transport roller 73a, which is a driven roller, rotates following the transport roller 73b while being pressed against the transport roller 73b.

While the drive roller 73b is stopped, the leading edge of the document 6 conveyed by the feed roller 72 located upstream in the conveying direction of the document 6 is pressed against the pressure contact between the conveying roller 73b and the conveying roller 73a of the first conveying roller 73. The first conveying roller 73 then bends the leading edge region of the document 6 to align the leading edge of the document 6 with the axial direction of the first conveying roller 73, and then starts conveying the document 6, thereby performing skew correction.

The automatic document feeder 33 also has a curved reading guide 78 that guides the document 6 to the reading position and also guides it from the reading position in the discharge direction, a back support member 80 that is provided on the reading guide 78 above the reading window 79 and supports the back of the document 6, a first size detection sensor 81 that is provided on the document storage section 70 and detects the size of the document 6 in the sub-scanning direction, and a second size detection sensor 82 that is also provided on the document storage section 70 and detects the size of the document 6 in the sub-scanning direction.

The housing 31 of the image reading device 3 is formed as a rectangular parallelepiped box with a portion of the top end surface open. The housing 31 has a top wall 312 facing the document pressing cover 32, a bottom wall 313 facing the top wall 312, side walls 314 and 315 facing the bottom wall 313 in the sub-scanning direction (left and right direction in FIG. 2), the above-mentioned front wall 311 (also see FIG. 1), and a rear wall 316 facing the front wall 311 in the main scanning direction (direction perpendicular to the paper surface in FIG. 2).

A large, flat rectangular opening 317 is formed in the upper wall 312 of the housing 31 at a location corresponding to the document reading position of the document 6 to be read in the second reading mode. A transparent document table 83 (platen glass) that supports the document 6 is arranged in the opening 317. A transparent reading window 79 for reading the document 6 in the first reading mode is provided on the document table 83's side facing the automatic document feeder 33. A guide member 84 with an inclined upper end surface is provided between the reading window 79 and the document table 83 to guide the document 6 that has passed the reading position to the transport roller 75 in the first reading mode.

The image reading device 3 is provided with an image reading unit having a light source 85 as an example of an illumination means, such as an illumination lamp or LED, which emits light to illuminate the original 6, a reflector 86 which reflects a part of the light emitted from the light source 85 toward the original 6, a first mirror 87 which receives the reflected light from the original 6, a second mirror 88 which receives the reflected light from the first mirror 87, a third mirror 89 which receives the reflected light from the second mirror 88, and an imaging lens 91 which focuses the reflected light from the third mirror 89 on an image reading element 90 as an example of an image reading means, such as a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The light source 85 emits light toward the original 6 and the reflector 86. The first to third mirrors 87 to 89 and the imaging lens 91 constitute a reading optical system for reading the image of the original 6 with the image reading element 90.

The light source 85, reflector 86, and first mirror 87 are arranged along the main scanning direction, which is the depth direction of the image reading device 3, and are attached to a first moving body 92 consisting of a carriage configured to be movable by a drive source described later along the sub-scanning direction, which is the width direction of the image reading device 3. The first moving body 92 is guided by a first rail 93. The first moving body 92 illuminates the reading target area of the original 6 while moving along the sub-scanning direction, and reflects the reflected light of the original 6 toward the second mirror 88 of the second moving body 94 by the first mirror 87. The first rail 93 is arranged along the sub-scanning direction on the rear wall 316 of the housing 31.

The second mirror 88 and the third mirror 89 are attached to a second moving body 94, which is a carriage arranged along the main scanning direction and movable by a driving means along the sub-scanning direction. The second moving body 94 reflects the reflected light from the original 6 toward the imaging lens 91 of the image reading section while moving in the sub-scanning direction guided by the second rail 95. The second rail 95 is arranged on the bottom wall 313 of the housing 31 along the sub-scanning direction. The first rail 93 and the second rail 95 are arranged so that one each faces both ends along the main scanning direction.

As shown in FIG. 9, the first and second moving bodies 92, 94 are driven by a drive motor 34, which is an example of a drive source arranged inside the housing 31 of the image reading device 3, via a drive pulley or a drive wire (not shown) so as to be capable of reciprocating movement along the sub-scanning direction.

As shown in FIG. 2, the image reading unit has an image reading board 97 on which an image reading element 90 is mounted. The imaging lens 91 and the image reading board 97 are attached to a base plate 96 supported by the bottom wall 313. In the image reading unit, the reflected light from the third mirror 89 passes through the imaging lens 91 and is imaged on the image reading element 90, which is made of a CCD or CMOS or the like, and the image of the original 6 is read by the image reading element 90, which outputs image data. The image data read by the image reading element 90 is subjected to predetermined image processing such as shading correction as necessary by an image processing device (not shown), and is sent to the control device 100 (see FIG. 1).

In the first reading mode, as shown by the solid lines in FIG. 2, the first and second moving bodies 92, 94 are stopped at the reading position set at the left end of the housing 31, and the document 6 is automatically transported by the automatic document feeder 33. The document 6 passing above the reading window 79 is illuminated by the light source 85, and the reflected light image from the document 6 is reflected by the first mirror 87 through the second and third mirrors 88, 89 to the imaging lens 91. The image reading unit forms an image of the reflected light image from the third mirror 89 on the image reading element 90 by the imaging lens 91, reads the image of the document 6 by the image reading element 90, and outputs image data from the image reading element 90.

On the other hand, in the second reading mode, the first moving body 92 and the second moving body 94 are driven by a driving source described later, and the movement amount of the second moving body 94 is configured to be 1/2 of the movement amount of the first moving body 92 so that the optical path length from the image reading position of the original 6 to the image reading element 90 does not change while the first moving body 92 moves along the sub-scanning direction. In FIG. 2, the two-dot chain line indicates the positions of the first moving body 92 and the second moving body 94 when the first moving body 92 moves near the end of the original 6 in the sub-scanning direction.

3, the image reading device 3 is provided with a sheet conveying device 320 that separates the originals 6, which are an example of sheets stored in the original storage section 70, one by one and conveys them to the reading position, and switches back the sheets that have passed the reading position to convey them again to the reading position in an inverted state. The sheet conveying device 320 includes a nudger roller 71, a feed roller 72, a pressure pad 72a, a first conveying roller 73, conveying rollers 74 and 75, a discharge roller 77, a drive motor 321 that is a drive source for driving these rollers, a constant direction rotation mechanism 322 that rotates the first conveying roller 73 in a constant direction regardless of the rotation direction of the drive motor 321, a first drive transmission switching means 323 that switches between a state in which a drive force is transmitted to the first conveying roller 73 and a state in which a drive force is not transmitted, and a second drive transmission switching means 324 that switches between a state in which a drive force is transmitted to the feed roller 72 and the nudger roller 71 and a state in which a drive force is not transmitted. In Figure 3, the dashed lines indicate the paths through which the driving force is transmitted.

As shown in FIG. 3, the sheet conveying device 320 includes a normal conveying path 325 that conveys the original 6 conveyed by the nudge roller 71 through the feed roller 72, the first conveying roller 73, the conveying rollers 74 and 75, and the discharge roller 77, and a reverse conveying path 326 that reverses the rotation direction of the discharge roller 77 to reverse the front and back of the original 6 and conveys it again to the first conveying roller 73. The normal conveying path 325 is divided into a plurality of paths along the normal conveying path 325, and includes guide members 325a and 325b that guide the front and back of the original 6, a reading guide 78, and a back support member 80. The reverse conveying path 326 includes guide members 326a and 326b that guide the front and back of the original 6. In addition, at a branching position where the normal transport path 325 and the reverse transport path 326 branch off, a switching gate 327 is provided for switching the transport path of the document 6 from the normal transport path 325 to the reverse transport path 326. The switching gate 327 is formed of an elastically deformable synthetic resin film or the like having a substantially Y-shaped cross section. The switching gate 327 is usually disposed such that a part of it diagonally crosses the normal transport path 325, as shown in FIG. 3. When the document 6 is transported along the normal transport path 325 to the discharge rollers 77, the switching gate 327 is pushed by the document 6 and elastically deforms to open the normal transport path 325, thereby switching the transport direction of the document 6 to the discharge rollers 77. Meanwhile, the switching gate 327 reverses the rotation direction of the discharge roller 77 while the discharge roller 77 is holding the rear end of the document 6, and when the document 6 is transported along the reverse transport path 326 to the first transport roller 73, the transport path of the document 6 transported by the discharge roller 77 is switched from the normal transport path 325 to the reverse transport path 326.

The sheet transport device 320 is provided with a document sensor 328 that detects the leading edge of the document 6 at a position corresponding to the nudger roller 71. In addition, a pre-registration sensor 329 that detects the leading edge of the document 6 is provided upstream of the first transport roller 73 in the transport direction of the document 6. The sheet transport device 320 further includes a registration sensor (not shown) that is disposed downstream of the transport roller 74 in the transport direction of the document 6 and detects the leading edge of the document 6, and an inverter sensor (not shown) that is disposed upstream of the discharge roller 77 in the transport direction of the document 6 and detects the trailing edge of the document 6.

The sheet transport device 320 is configured to read an image on the back side of the document 6 by transporting the document 6 to the reversing transport path 326. However, instead of providing the reversing transport path 326, a second image reading element (not shown) that reads an image on the back side (second side) of the document 6 may be disposed midway along the normal transport path 325, thereby making it possible to read images on both the front and back sides of the document 6 without reversing the transport direction of the document 6.

In this case, the reverse transport path 326 is unnecessary, but a second image reading element must be newly installed. Therefore, since the second image reading element itself of the image reading device 3 has a certain weight, the automatic document feeder 33 may become even heavier.

<Configuration of Main Parts of Image Reading Device>
The image reading device 3 according to the first embodiment includes an automatic document feeder 33 as an example of a document pressing means, as shown in FIG. 4. The automatic document feeder 33 includes a document pressing cover 32 as described above. The document pressing cover 32 includes a white sheet-like pressing member 32a on the lower surface thereof for pressing a document (not shown) placed on the document table 83. The pressing member 32a is formed in a planar rectangular shape having a size substantially equal to that of the document table 83. The automatic document feeder 33 separates the documents 6 set in the automatic document feeder 33 one by one and conveys them to a reading position. The automatic document feeder 33 includes conveying members such as a nudger roller 71, a feed roller 72, a first conveying roller 73, conveying rollers 74 and 75, and a discharge roller 77 for conveying the documents 6, and a drive motor 321 (see FIG. 3) as a driving source for driving these members. Therefore, the automatic document feeder 33 tends to be heavy (heavy) in overall weight, as described above.

In the image reading device 3, in the second reading mode, when the document 6 is placed on the document table 83 and an image of the document 6 is read, the operator must manually open and close the automatic document feeder 33. Therefore, as the weight of the automatic document feeder 33 increases, the operating force required to open and close the automatic document feeder 33 also increases. Therefore, it is desirable to improve the operability of the image reading device 3 by reducing the operating force required to open and close the automatic document feeder 33.

As a technology that can improve operability when opening and closing the automatic document feeder 33, a technology has already been proposed that detects the opening and closing angle of the automatic document feeder 33 and controls the opening and closing speed of the automatic document feeder 33 according to the opening and closing angle of the automatic document feeder 33, as described in the above-mentioned Patent Document 1.

However, if the image reading device 3 is configured to detect the opening/closing angle of the automatic document feeder 33 and control the opening/closing speed of the automatic document feeder 33 according to the opening/closing angle of the automatic document feeder 33, when an operation to open or close the automatic document feeder 33 is performed, for example when a heavy object such as a book is placed on the automatic document feeder 33, an excessive load is placed on the drive means for opening and closing the automatic document feeder 33, which may damage the gears of the drive means or cause malfunctions in the opening and closing operation, resulting in a technical problem of impaired operability.

The image reading device 3 according to this embodiment 1 is configured to include an automatic document feeder 33 that is openably and closably mounted on the housing 31 and feeds the document 6 to the reading position, and an opening force application means that applies the driving force of the drive motor 34 to the automatic document feeder 33 only temporarily as an opening force (force in the opening direction) when the automatic document feeder 33 is opened.

Here, "temporary" means that the force does not last long only when the automatic document feeder 33 is opened from a completely closed state, and does not mean that the opening force is not applied after the automatic document feeder 33 is completely open. The opening force applied to the automatic document feeder 33 is limited to a short period of time at the beginning of opening when the automatic document feeder 33 is opened from a closed state, for example.

That is, in the image reading device 3 according to the first embodiment, as shown in Fig. 4, the automatic document feeder 33 is mounted on the housing 31 of the image reading device 3 via first and second shaft support members _43-1 , _43-2 so as to be openable and closable. The first and second shaft support members _43-1 , _43-2 have bearings _44-1 , _44-2 provided on the housing 31 side of the image reading device 3, and reading rotation units 45-1, _45-2 provided on the automatic document feeder 33 side. The bearings _44-1 , _44-2 and the reading rotation units _45-1 , _45-2 are rotatably connected to each other around rotation shafts _46-1 , _46-2 as shown in Fig. 5. The reading rotation units _45-1 , _45-2 have built-in counterbalances (not shown) that apply a rotation moment in _an opening direction to the automatic document feeder 33 in order to reduce the load when the automatic document feeder 33 is opened and closed. The counterbalance includes a coil spring (not shown) or the like that applies a rotational moment in an opening direction to the automatic document feeder 33 in accordance with the opening/closing angle of the automatic document feeder 33. Of course, the counterbalance may be disposed on the bearings _44.sub.1 and _44.sub.2 side.

The original 6 whose image is read by the image reading device 3 is not limited to an original 6 cut to a desired size such as A4 size or A3 size, but also includes a so-called book original having an original 6 spanning multiple pages, such as a closed book of multiple sheets of original 6. To read the image of a book original with the image reading device 3, as shown in FIG. 4, the automatic document feeder 33 is opened, the book original is placed on the document table 83 with the image of the page to be read facing down, and the automatic document feeder 33 is closed.

In this case, since a book document has a certain degree of thickness, if the automatic document feeder 33 is simply configured to be able to open and close using the first and second shaft support members _43-1 , _43-2 as fulcrums, even if the automatic document feeder 33 is closed when reading an image of the book document, the automatic document feeder 33 will be inclined with respect to the top surface of the book document and will not be able to press down on the entire surface of the book document.

5(b) and 5(c), the first and second shaft support members ₄₃₁ , ₄₃₂ which support the automatic document feeder 33 so as to be openable and closable have cylindrical lifting sections _441a , _442a provided on the bearing sections 441, ₄₄₂ arranged on the housing 31 side of the image reading device 3. _The lifting sections _441a , _442a of the bearing sections ₄₄₁ , ₄₄₂ are removably inserted into holes 31a provided in the housing 31. The first and second shaft support members 43 ₁ , 43 ₂ are configured so that, when reading an image of an original 6 having a certain degree of thickness, such as a book original, the lifting portions 44 _{1 a} , 44 2 a of the bearing portions 44 ₁ , 44 ₂ inserted into the hole portions 31 _a provided in the housing 31 move upward, enabling the automatic document feeder 33 to press down on the entire surface of the book original so that it is approximately parallel to the top surface of the book original.

4, the left end of the automatic document feeder 33 in the figure, where the transport means for automatically transporting the document 6 is built in, is heavier than the right end. As a result, the center of gravity of the automatic document feeder 33 is located at a position biased toward the left side in the figure, where the transport means for automatically transporting the document 6 is built in, rather than the center along the width direction. Therefore, the counterbalances built into the first and second shaft support members _43-1 and _43-2 are set so that the first counterbalance arranged on the left side in the figure, which is the drive side of the automatic document feeder 33, applies a larger rotational moment to the automatic document feeder 33 than the second counterbalance arranged on the right side, which is the non-drive side of the automatic document feeder 33.

FIG. 6 is a graph showing the results of determining the respective values of the rotational moment _M1 required to open the automatic document feeder 33 from a closed state (opening angle = 0 degrees), the rotational moment _M2 applied to the automatic document feeder 33 by the first shaft support member _43-1 , the rotational moment _M3 applied to the automatic document feeder 33 by the second shaft support member 43-2, and the combined rotational moment M _-T applied to the automatic document feeder 33 by the _first and second shaft support members _43-1 , _43-2 , according to the opening/closing angle of the automatic document feeder 33.

In the image reading device 3 according to the first embodiment, in order to reduce the operating force of the operator when opening the automatic document feeder 33 as much as possible, when the automatic document feeder 33 is opened to a predetermined angle θ of about 5 to 25 degrees (for example, 10 degrees), the rotation moment M ₁ required to open the automatic document feeder 33 and the composite rotation moment M _T of the first and second shaft support members 43 ₁ , 43 ₂ are set to be equal. The period until the composite rotation moment M _T exceeds the value of the rotation moment M ₁ is only a temporary example in this embodiment. In addition, when the opening angle of the automatic document feeder 33 exceeds the predetermined angle θ, the composite rotation moment M _T of the first and second shaft support members 43 ₁ , 43 ₂ is set to be larger than the rotation moment M ₁ required to open the automatic document feeder 33. As a result, the operator can easily perform the operation of opening the automatic document feeder 33 in an angle range exceeding the predetermined angle θ. However, it is desirable that the first and second shaft support members 43 ₁ , 43 ₂ prevent the automatic document feeder 33 from opening unintentionally when the operator stops the operation to open the automatic document feeder 33, even if the opening angle of the automatic document feeder 33 exceeds the predetermined angle θ. Therefore, the first and second shaft support members 43 ₁ , 43 ₂ are configured to apply a frictional force sufficient to maintain the opening angle when the operator releases the automatic document feeder 33, even if the opening angle of the automatic document feeder 33 exceeds the predetermined angle θ.

Furthermore, even when the automatic document feeder 33 is in a completely closed state (opening angle = 0 degrees), a resultant rotational moment M _{1 T} in the opening direction is acting on the automatic document feeder 33 by the first and second pivot members 43 ₁ , 43 _2. At this time, the required resultant rotational moment M _{1 T} acting on the automatic document feeder 33 by the first and second pivot members 43 ₁ , 43 ₂ is slightly smaller by ΔM than the rotational moment M ₁ required to open the automatic document feeder 33, as shown in FIG.

From the viewpoint of reducing the operating force, the period during which the driving force is applied is preferably the period until the resultant rotational moment M _T certainly exceeds the value of the rotational moment M ₁ , and in that case, it is advisable to apply a little more driving force, taking into consideration the individual differences of the device, etc. On the other hand, in order to minimize the driving period, it is possible to aim for a period slightly before the angle θ, but even in that case, it is better to apply the driving force until ΔM becomes sufficiently small, for example, until it becomes 10% or less of ΔM at the angle of 0 degrees.

In addition, if the driving force is continued for a long time, problems may occur. For example, if the automatic document feeder 33 is fully opened to replace the document, it takes time to open and close, so it is not opened all the way, but only opened to a certain extent. If a user replaces the document in that state and then tries to close the automatic document feeder 33 again, the automatic document feeder 33 may not be able to be closed if the driving force is applied, or unnecessary load may be placed on the driving source and the parts that receive the driving force from it.

As shown in FIG. 5(a), the image reading device 3 includes a reed switch 220 and a magnetic member 221 as an example of a detection means for detecting the opening and closing of the automatic document feeder 33. The reed switch 220 is provided in the housing 31 of the image reading device 3, for example, on the front side of the reading window 79. As shown in FIG. 7, the reed switch 220 includes a first reed 222 made of a ferromagnetic material magnetized at one end to an S pole and at the other end to an N pole, and a second reed 223 made of a ferromagnetic material magnetized at one end to an N pole and at the other end to an S pole, which are sealed inside the switch body 224. The other end of the first reed 222 and the other end of the second reed 223 are provided with first and second contact portions 225 and 226, respectively. The reed switch 220 is attached so that the second reed 223 is located on the surface side of the housing 31.

On the other hand, a magnetic member 221 is attached to the automatic document feeder 33 at a position corresponding to the reed switch 220 on the housing 31 of the image reading device 3. The magnetic member 221 is made of a long, thin permanent magnet with a south pole and a north pole magnetized at both ends. The magnetic member 221 is positioned so that the south pole is located on the underside of the automatic document feeder 33.

As shown in Figures 7(b) and 8, when the automatic document feeder 33 is closed, the S pole of the magnetic member 221 approaches the second contact portion 226 of the S pole of the second reed 223, and the second contact portion 226 of the S pole and the first contact portion 225 of the N pole are brought into contact with the first contact portion 225 of the N pole of the first reed 222 due to the magnetic repulsive force of the second contact portion 226 of the S pole and the magnetic attractive force of the first contact portion 225 of the N pole of the second reed 223, thereby turning on the reed switch 220. On the other hand, as shown in FIG. 5(a) and FIG. 7(a), when the automatic document feeder 33 is opened, the S pole of the magnetic member 221 moves away from the reed switch 220, and the second contact portion 226 of the second reed 223 moves away from the first contact portion 225 of the first reed 222 due to the elastic restoring force of the first contact portion 225 consisting of the N pole and the second contact portion 226 consisting of the S pole, turning the reed switch 220 to the OFF state.

In this way, the reed switch 220 can detect the opening and closing of the automatic document feeder 33 with a simple configuration and high accuracy by determining whether it is in an on or off state.

The detection means for detecting the opening and closing of the automatic document feeder 33 is not limited to the combination of the reed switch 220 and the magnetic member 221, but may be a mechanical switch having a contact member that appears and disappears when the automatic document feeder 33 is opened or closed near the opening and closing fulcrum of the automatic document feeder 33, or an optical switch that optically detects the opening and closing of the automatic document feeder 33.

As shown in FIG. 5, in the image reading device 3 according to this embodiment 1, a push-up device 200 is provided on the rear part within the housing 31 of the image reading device 3 as an example of an opening force application means for applying the driving force of the drive source to the automatic document feeder 33 only temporarily as an opening force when the operator opens the automatic document feeder 33.

In this embodiment 1, as shown in FIG. 9, the push-up device 200 does not have its own drive source, and uses the drive motor 34 that drives the reading optical system of the image reading device 3 as its drive source. Of course, the push-up device 200 may have its own drive source.

As shown in FIG. 10, a drive pulley 201 for driving the reading optical system and a drive gear 202 for driving the push-up device 200 are attached to the drive shaft 341 of the drive motor 34. As shown in FIG. 9, a timing belt 204 is wound around the drive pulley 201 and a driven pulley 203 that drives the reading optical system of the image reading device 3.

As shown in FIG. 10, in the second reading mode, the drive motor 34 is driven to rotate in the forward and reverse directions when reading an image of the document 6. The drive gear 202 is engaged with a drive force transmission gear 205 incorporating an electromagnetic clutch 205c as an example of a switching means for switching whether or not the rotational drive force of the drive motor 34 is transmitted to the push-up device 200. The drive force transmission gear 205 has a first drive force transmission gear 205a having a relatively large outer diameter on the input side, and a second drive force transmission gear 205b having a relatively small outer diameter on the output side. The second drive force transmission gear 205b is engaged with a reciprocating gear 208 that reciprocates a link mechanism 207 via a drive wire 206 as an example of a wire member.

The reciprocating gear 208 has an engagement pin 209 that protrudes to the side from the outer circumferential end of one side of the gear. One end of the drive wire 206 is rotatably engaged with the engagement pin 209. The other end of the drive wire 206 is engaged with the link mechanism 207.

9, the link mechanism 207 is attached to a support plate 210 provided in an upright state on the bottom of the housing 31 of the image reading device 3. When the lower end of the link mechanism 207 is moved horizontally, the upper end of the link mechanism 207 rotates about a rotation fulcrum 215 located in the middle so as to push up the lower surface of the automatic document feeder 33. The position where the link mechanism 207 pushes up the automatic document feeder 33 is set to be on the front side of the image reading device 3 from the rotation shafts _46-1 , _46-2 of the first and second shaft support members _43-1 , _43-2 and on the rear side from the document table 83, which is the reading position of the document 6, as shown in FIG. If the position at which the link mechanism 207 pushes up the automatic document feeder 33 is farther from the rotation shafts _46-1 , _46-2 of the first and second shaft support members _43-1 , _43-2 , the distance between the point of action that applies a pushing force to the automatic document feeder 33 and the rotation shafts _46-1 , _46-2 becomes longer, and the rotation moment M acting on the automatic document feeder 33 becomes larger.

However, the rotation moment M acting on the automatic document feeder 33 by the link mechanism 207 pushing up the automatic document feeder 33 may be equal to or greater than the difference ΔM between the rotation moment M1 required to open the automatic document feeder 33 and the resultant rotation moment M _T that the counterbalance of the _first and second shaft support members _43-1 , _43-2 gives to the automatic document feeder 33, as shown in Fig. 6. Therefore, the link mechanism 207 does not need to apply a very large rotation moment M to the automatic document feeder 33, and the link mechanism 207 can be disposed close to the rotation shafts _46-1 , _46-2 of the first and second shaft support members _43-1 , _43-2 . Therefore, the link mechanism 207 may be disposed close to the rear surface of the housing 31 of the image reading device 3, and the housing 31 of the image reading device 3 is prevented from becoming large in size.

As shown in FIG. 9, the link mechanism 207 has a first link member 211 whose upper end 211a abuts against the underside of the automatic document feeder 33 in the closed state and whose lower end 211b is supported so as to be movable along the horizontal direction, and a second link member 212 whose upper end 212a is rotatably connected to the middle of the first link member 211 and whose lower end 212b is supported so as to be movable along the horizontal direction.

As shown in Figs. 9 and 10, the first link member 211 is formed in a long and narrow flat plate shape. The lower end 211b of the first link member 211 is attached to the first guide groove 213 provided in the support plate 210 via the first sliding shaft 214 so as to be movable along the horizontal direction in a state along the surface of the support plate 210. The first guide groove 213 is provided in the support plate 210 over a required length along the horizontal direction. The upper end 211a of the first link member 211 stops at a position where it abuts against the lower end surface of the automatic document feeder 33. The tip of the drive wire 206 is rotatably connected to the lower end 211b of the first link member 211 via the first sliding shaft 214.

On the other hand, the second link member 212 is formed in a long and narrow flat plate shape shorter than the first link member 211. The upper end 212a of the second link member 212 is rotatably connected to a rotation fulcrum 215 located in the middle along the longitudinal direction of the first link member 211. The connection position of the second link member 212 becomes the rotation fulcrum 215 when the first link member 211 rotates in the upright direction. The lower end 212b of the second link member 212 is attached to a second guide groove 216 provided in the support plate 210 via a second sliding shaft 217 at a position lower than the lower end 211b of the first link member 211 so as to be movable along the horizontal direction in a state along the surface of the support plate 210. The support plate 210 is provided with a second guide groove 216 for guiding the lower end 212b of the second link member 212 over a required length along the horizontal direction.

As shown in Figures 11 and 12, when the drive motor 34 is driven to rotate in a required direction, the link mechanism 207 rotates the reciprocating gear 208 in a counterclockwise direction in the figure, and the drive wire 206 connected to the engagement pin 209 of the reciprocating gear 208 moves to the left in the figure. Then, the drive wire 206 is pulled to the left in the figure together with the rotation of the reciprocating gear 208, and moves the lower end 211b of the first link member 211 to the left along the horizontal direction.

The second link member 212 is connected to the middle of the first link member 211 so as to be rotatable about a rotation fulcrum 215. Therefore, as shown in FIG. 11, the upper end 211a of the first link member 211 rotates in the clockwise direction in the figure about the rotation fulcrum 215. Furthermore, as the first link member 211 rotates in the clockwise direction, the rotation fulcrum 215, which is the connection position with the first link member 211, of the second link member 212 moves upward. Therefore, as the first link member 211 rotates in the clockwise direction, the upper end 212a of the second link member 212 moves to the right in the figure, and the lower end 212b also moves to the right in the figure.

The first link member 211 rotates clockwise in the figure around the rotation fulcrum 215 with the second link member 212 due to the tension of the drive wire 206 acting on its lower end 211b. At the same time, the upper end 211a of the first link member 211 protrudes upward from the upper end surface of the housing 31 of the image reading device 3, pushing up the automatic document feeder 33 and assisting the operator in opening the automatic document feeder 33.

As shown in FIG. 4, the upper wall 312 of the housing 31 of the image reading device 3 has a slit-shaped opening 312a through which the first link member 211 appears and disappears.

When the operator opens the automatic document feeder 33, the drive motor 34 is driven only temporarily for a predetermined time T to push up the automatic document feeder 33 via the link mechanism 207, opens the automatic document feeder 33 to a set angle that is several degrees (1 to 2 degrees) larger than the predetermined angle θ, then stops and is immediately driven to rotate in the opposite direction to finish pushing up the automatic document feeder 33.

Here, the predetermined time T for which the drive motor 34 is rotated, i.e., the fixed time T, has the same meaning as "temporary" described above, and means that it does not last long only when the automatic document feeder 33 is opened from a completely closed state, and does not mean that the opening force is not applied after the automatic document feeder 33 is completely opened.

The predetermined angle θ is, for example, an angle at which the rotation moment M ₁ required to open the automatic document feeder 33 is equal to the composite rotation moment M _T of the first and second shaft support members 43 ₁ and 43 ₂ .

In addition, instead of the drive wire 206 being rotatably connected to the reciprocating gear 208 via the engagement pin 209, a take-up reel (not shown) may be provided in place of the reciprocating gear 208, and one end of the drive wire 206 may be fixed to the take-up reel so that the drive wire 206 is taken up by the take-up reel.

However, in the image reading device 3 according to this embodiment 1, when the automatic document feeder 33 is closed and a heavy object such as a book is placed on the automatic document feeder 33, the automatic document feeder 33 does not open even when the link mechanism 207 is driven, and there is a risk that an excessive load will be placed on the drive motor 34 that drives the link mechanism 207.

In addition, in the image reading device 3 according to this embodiment 1, the operator may perform an operation to open the automatic document feeder 33 once, and then perform an operation to close the automatic document feeder 33 before the automatic document feeder 33 opens by the predetermined angle θ. In this case, the image reading device 3 may forcibly close the automatic document feeder 33 while driving the link mechanism 207 to open the automatic document feeder 33 by the predetermined angle θ, and there is a risk that an excessive load may be applied to the drive motor 34 that drives the link mechanism 207.

The image reading device 3 according to this embodiment 1 is provided with an absorbing means 240 that absorbs excessive force when an excessive force exceeding a predetermined value acts on the push-up device 200. The absorbing means 240 is an example of an elastic member that absorbs the excessive force by elastically deforming when an excessive force acts on the push-up device 200.

To explain further, in the image reading device 3, a coil spring 241 as an example of an absorption means 240 is interposed in the middle of the drive wire 206 that transmits the drive force of the drive motor 34 to the link mechanism 207. The coil spring 241 has a required spring constant. The spring constant of the coil spring 241 is set to a value that is greater than the tension acting on the drive wire 206 when the link mechanism 207 pushes up the automatic document feeder 33 and smaller than the tension when a load exceeding a predetermined value acts on the push-up device 200, such as when a heavy object is placed on the automatic document feeder 33. Therefore, the coil spring 241 extends to a certain length L2 when the link mechanism 207 pushes up the automatic document feeder 33, but the length L2 of the coil spring 241 is shorter than the length L3 when a load exceeding a predetermined value acts on the push-up device 200, as shown in FIG. 14. The coil spring 241 has a length of L1 before tension acts on the drive wire 206.

In this embodiment 1, when an excessive load is applied to the drive motor 34, the coil spring 241 expands and absorbs the excessive load acting on the drive motor 34. This prevents the drive motor 34 from overheating and breaking due to an overload, and prevents the teeth of the reciprocating gear 208 that transmits the drive force from chipping or going out of sync.

Figure 13 is a block diagram showing the control device 100 of the image forming device 1 according to this embodiment 1.

As shown in FIG. 13, the control device 100 includes a control unit 101 as an example of a control means, a timer unit 102 that measures time, and a memory unit 103 as an example of a memory means.

The control unit 101 executes a program stored in the memory unit 103 to comprehensively control the operation of the image forming device 1, including the image reading operation by the image reading device 3. The control unit 101 executes the formation operation of color images, etc., by driving the image forming unit 2, which is composed of a charging device, an exposure device, a developing device, a primary transfer device, etc. (not shown) in each of the imaging devices 10 (Y, M, C, K) for yellow (Y), magenta (M), cyan (C), and black (K).

The control unit 101 also controls the reading operation of the image reading device 3 via the timing unit 102, memory unit 103, etc.

When the control unit 101 detects that the automatic document feeder 33 has transitioned from a closed state to an open state based on the open/close signal of the automatic document feeder 33 input from the reed switch 220, it drives the drive motor 34 for a predetermined time T (only temporarily). Here, the predetermined time T is set, for example, to the time required for the drive motor 34 to open the automatic document feeder 33 by a set angle that is several degrees (1 to 2 degrees) larger than the predetermined angle θ.

At the same time, the timer unit 102 measures the elapsed time when it detects that the automatic document feeder 33 has transitioned from a closed state to an open state based on the open/close signal of the automatic document feeder 33 input from the reed switch 220. Then, when the timer unit 102 measures that a predetermined time T has elapsed, it outputs an elapsed signal to the control unit 101.

When the control unit 101 receives the elapsed time signal output from the timer unit 102, it stops the drive motor 34 and then controls the drive motor 34 to rotate in the reverse direction for a predetermined time T and then stop.

The control unit 101 also drives the electromagnetic clutch 205c to turn on and off at the required timing. The timing at which the control unit 101 turns the electromagnetic clutch 205c on is set when it detects that the automatic document feeder 33 is open, based on an open/close signal of the automatic document feeder 33 input from the reed switch 220. The timing at which the control unit 101 turns the electromagnetic clutch 205c off is set when a predetermined time T has elapsed since the electromagnetic clutch 205c was turned on.

<Operation of the image reading device>
In the image forming apparatus 1 to which the image reading device 3 of this embodiment 1 is applied, when copying an image of an original 6 or reading an image of an original 6 and sending it via a facsimile function, etc., it is possible to reduce the operating force required to open the automatic document feeder 33 without impairing operability, compared to when the automatic document feeder 33 in the image reading device 3 is driven to open and close over the entire range of opening and closing angles, as described below.

In other words, as shown in FIG. 4, when the image of the original 6 is read in the second reading mode in the image reading device 3 of the image forming device 1, the automatic document feeder 33 functioning as an original pressing means is opened, the original 6 is placed on the original table (platen glass) 83 provided on the upper end surface of the housing 31 of the image reading device 3, and after closing the automatic document feeder 33, the desired copy operation, etc. is performed using the control panel 66 of the image forming device 1.

Depending on the operation specified on the control panel 66, the image reading device 3 reads the image of the original 6 using the image reading device 3, forms the image of the original 6 on the recording paper 5 using the image forming unit 2 of the image forming device 1, transmits the image of the original 6 read by the image reading device 3 to a personal computer (not shown), or transmits the image of the original 6 read by the image reading device 3 using a facsimile function.

In the image reading device 3 that reads the image of the original 6, the automatic document feeder 33 is equipped with a transport member and a drive motor 321 for automatically transporting the original 6 in the first reading mode, and is relatively heavy. Therefore, in the image reading device 3, when the original 6 is placed on the document table 83 and the automatic document feeder 33 holds the original 6 down to read the image of the original 6 in the second reading mode, the operator must open and close the automatic document feeder 33, which is relatively heavy.

When an operator opens the automatic document feeder 33, the image reading device 3 detects that the automatic document feeder 33 has been opened by the reed switch 220.

As shown in FIG. 13, when the control unit 101 of the control device 100 detects that the automatic document feeder 33 has been opened by the signal from the reed switch 220 transitioning from an ON state to an OFF state, it turns on the electromagnetic clutch 205c of the driving force transmission gear 205 and simultaneously drives the drive motor 34 to rotate for a predetermined time T (only temporarily).

As shown in FIG. 9, when the drive motor 34 of the image reading device 3 is driven to rotate, the drive force transmission gear 205 is driven to rotate by the drive motor 34. Since the electromagnetic clutch 205c of the drive force transmission gear 205 is in the ON state, the rotational drive force from the drive motor 34 is transmitted to the second drive force transmission gear 205b, and the reciprocating gear 208 is driven to rotate by the required angle in the counterclockwise direction in the figure.

Then, a tension acts on the drive wire 206, one end of which is connected to the reciprocating gear 208, pulling it to the left in the figure, and moves the lower end 211b of the first link member 211 of the link mechanism 207 to the left in the figure via the coil spring 241.

As shown in FIG. 11, when the lower end 211b of the first link member 211 moves to the left in the figure, the upper end 211a rotates clockwise around the rotation fulcrum 215 located in the middle, pushing up the lower surface of the automatic document feeder 33 and opening the automatic document feeder 33.

Therefore, when an operator opens the automatic document feeder 33, the operation of opening the automatic document feeder 33 is assisted by the pushing up action of the first link member 211, so that the operator can easily open the automatic document feeder 33 regardless of the weight of the automatic document feeder 33.

6, the angle at which the first link member 211 opens the automatic document feeder 33 is set to a setting angle that is several degrees (1 to 2 degrees) larger than the predetermined angle θ. Therefore, after the operator is assisted in opening the automatic document feeder 33 by the first link member 211, the operator can easily open the automatic document feeder 33 to the fully open position by the resultant rotation moment M _T acting due to the counterbalance built into the first and second shaft support members 43 ₁ and 43 ₂ .

When the timer unit 102 of the control device 100 has timed the passage of a predetermined time T, the control unit 101 stops the drive motor 34 and then immediately rotates it in the reverse direction for the predetermined time T. At the same time as stopping the drive motor 34, the control unit 101 also turns off the electromagnetic clutch 205c.

Then, as the drive motor 34 rotates in the reverse direction, as shown in FIG. 9, the drive wire 206, one end of which is connected to the reciprocating gear 208, moves to the right in the figure, moving the lower end 211b of the first link member 211 of the link mechanism 207 to the right in the figure.

When the lower end 211b of the first link member 211 moves to the right in the figure, the upper end 211a rotates counterclockwise around the rotation fulcrum 215 located in the middle and moves downward, moving away from the underside of the automatic document feeder 33.

In addition, in this embodiment 1, when the electromagnetic clutch 205c is turned off, the second driving force transmission gear 205b of the driving force transmission gear 205 becomes freely rotatable, and the action of pulling the driving wire 206 is released.

In this way, in the image reading device 3 according to the first embodiment, the reed switch 220 detects the operation of the operator to open the automatic document feeder 33, and the drive motor 34 is driven, so that the automatic document feeder 33 is pushed up only temporarily by the drive wire 206 and the link mechanism 207. Therefore, even if the automatic document feeder 33 has a relatively large weight to a certain extent, the operation of opening the automatic document feeder 33 by the operator is assisted by the drive motor 34, and the operation of opening the automatic document feeder 33 can be easily performed.

In addition, in the image reading device 3 according to the above-mentioned embodiment 1, even when a heavy object such as a book (not shown) is placed on the automatic document feeder 33, or when the operator closes the automatic document feeder 33 while opening it, the coil spring 241 is interposed in the middle of the drive wire 206 as shown in FIG. 14, and the coil spring 241 extends by a length L3 to absorb the excess load, thereby preventing the excess load from acting on the drive motor 34.

Therefore, according to the image reading device 3 of this embodiment 1, it is possible to reduce the operating force required to open the automatic document feeder 33 without compromising operability, compared to when the automatic document feeder 33 is driven to open and close over the entire range of opening and closing angles.

[Embodiment 2]
15 and 16 are diagrams showing the configuration of an image reading device according to a second embodiment of the present invention.

As shown in FIG. 15, the image reading device 3 according to this second embodiment is configured so that the automatic document feeder 33 is not directly pushed up by the link mechanism 207, but is pushed up via a flat anti-fall member 300 that is disposed on the rear side of the housing 31 of the image reading device 3 and prevents the document 6 from falling from the upper wall 312 of the housing 31 to the rear side.

The housing 31 of the image reading device 3 is provided with a guide member 301 that guides the fall prevention member 300 so that it can be raised and lowered in the up-down direction (vertical direction). The fall prevention member 300 has guide portions 300a at both ends along its width direction that are guided in the up-down direction by the guide member 301. The guide member 301 supports the fall prevention member 300 with a certain degree of frictional force, and is configured to be able to hold the raised position of the fall prevention member 300 when it moves upward.

As in the first embodiment, the upper end 211a of the first link member 211 of the link mechanism 207 is arranged to abut against the lower end of the fall prevention member 300. The link mechanism 207 is driven by the drive motor 34.

In this second embodiment, as shown in FIG. 16, when an operator opens the automatic document feeder 33, the drive motor 34 is rotated and the fall prevention member 300 moves upward via the link mechanism 207, and the automatic document feeder 33 is pushed up and opened by the fall prevention member 300.

In this way, the fall prevention member 300 pushes up the automatic document feeder 33 with its upper end surface, so that the pushing force acts uniformly on the automatic document feeder 33, allowing the pushing up operation to be performed smoothly, compared to when the automatic document feeder 33 is pushed up with the upper end 211a of the first link member 211 of the link mechanism 207.

Thereafter, the drive motor 34 is rotated in the reverse direction after being stopped, and the link mechanism 207 descends, but the fall prevention member 300 maintains the raised position due to the frictional force of the guide member 301. Therefore, in the image reading device 3 according to the second embodiment, even when the automatic document feeder 33 is open, the original 6 is prevented from falling to the rear side from between the first and second pivot support members _43-1 and _43-2 . The raised fall prevention member 300 is pushed down by the automatic document feeder 33 when the automatic document feeder 33 is closed.

The rest of the configuration and operation are the same as in the first embodiment, so their explanation will be omitted.

In the above embodiment, the image reading device is described as being applied to a color copier as an example of an image forming device, but the present invention is not limited to this, and the image reading device may of course be used as a scanner, fax machine, etc.

In addition, in the above embodiment, a coil spring is used as the absorbing means, but the absorbing means may be configured to include a torque limiter that limits the driving torque in the driving force transmission gear 205, etc.

REFERENCE SIGNS LIST 1... image forming apparatus 1a... image forming apparatus main body 3... image reading device 31... housing of image reading device 33... automatic document feeder 34... drive motor 206... drive wire 207... link mechanism 211... first link member 212... second link member

Claims (14)

a document pressing means that is attached to the device body so as to be openable and closable and that presses down a document;
an opening force application means for applying a driving force of a driving source to the document pressing means as an opening force only temporarily when the document pressing means is opened;
An image reading device comprising: a detection means for detecting opening and closing of the document pressing means;
a driving means for driving the driving source for a fixed period of time when the detection means detects that the document pressing means is in an open state;
The image reading device according to claim 1 . 3. The image reading apparatus according to claim 2, wherein the driving means drives the driving source until the open angle of the document holder reaches a predetermined angle after the detection means detects that the document holder is in an open state. a counterbalance that applies a force in an opening direction to the document pressing means;
3. The image reading device according to claim 2, wherein the driving means drives the driving source until the rotational moment required to open the document holding means becomes equal to or less than the rotational moment caused by the force of the counterbalance in the opening direction, and stops the driving source after the rotational moment becomes equal to or less than the rotational moment . 3. The image reading device according to claim 2 , wherein the drive means rotates in a reverse direction after the temporary drive to release the force applied to the opening force application means. The image reading device according to claim 1, wherein the opening force application means applies an opening force to a position forward of a fulcrum that supports the document pressing means so that the document can be opened and closed, and rearward of a reading position of the document. The image reading device according to claim 5, wherein the opening force application means applies a pushing-up force to the document pressing means. The image reading device according to claim 1, further comprising an absorbing means for absorbing an excessive force when an excessive force exceeding a predetermined value acts on the opening force applying means. The image reading device according to claim 8, wherein the absorbing means is made of an elastic member that absorbs the excessive force by elastically deforming when the excessive force acts on the opening force applying means. the opening force applying means is a link mechanism that rotates around a fulcrum located in the middle of the link mechanism so that an upper end of the link mechanism pushes up the document pressing means by moving a lower end of the link mechanism in a horizontal direction;
a wire member that moves a lower end of the link mechanism by a driving force of the driving source;
2. The image reading device according to claim 1, further comprising: The link mechanism includes a first link member having an upper end that contacts the document pressing means and a lower end that is supported so as to be movable along a horizontal direction;
a second link member having an upper end rotatably connected to the middle of the first link member and a lower end supported so as to be movable along a horizontal direction;
11. The image reading device according to claim 10, further comprising: an image reading means for reading an image of the document conveyed to a reading position by the document pressing means;
2. The image reading apparatus according to claim 1, wherein the driving source comprises a driving source for the image reading means. 13. The image reading apparatus according to claim 12, wherein the document pressing means cuts off power supply to the driving source when the document pressing means is open. an image reading means for reading an image of the document;
an image forming means for forming an image of the document read by the image reading means;
Equipped with
14. An image forming apparatus using the image reading device according to claim 1 as said image reading means.

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