Hinge mechanism, image reading device, and image forming device

Abstract

To make a hinge mechanism compact in the vertical direction.SOLUTION: A hinge mechanism (3) has: a first member (31) that is fixed to an image reading unit; a first shaft (35); a second member (32) that rotates with respect to the first member; a second shaft (36); a third member (33) that rotates with respect to the second member; a third shaft (38); a fourth member (34) that rotates with respect to the third member so that a document conveying unit is fixed and a first contact part and a second contact part are in contact with a light transmissive member; a first urging part that has a first spring providing torque in a direction to open the document conveying unit; and a second urging part (F2) that has a second spring (39) providing torque to the fourth member so that the second contact part is in contact with the light transmissive member. The second spring (39) is arranged outside a first side plate (34d) of the fourth member (34) in an axial direction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0003]

[0001] The present invention relates to a hinge mechanism that supports a document conveyance unit so as to be openable and closable with respect to a document reading unit. and hinge mechanism and includes image a reading device and an image forming apparatus.

Background Art

[0002] Conventionally, for example, some image forming apparatuses such as copiers, FAX machines, and multifunction printers include a document reading device that reads documents from above. Further, some of these document reading devices include an image reading unit that reads an image of a document and a document conveyance unit (hereinafter referred to as "ADF") that automatically conveys the document toward the document reading unit. Generally, such a document reading device is configured to be capable of performing so-called fixed reading in which a document is fixed on a fixed reading glass of the document reading unit and an image is read, and so-called continuous reading in which a document conveyed from the ADF passes through a continuous reading glass and an image is read. Therefore, the ADF is supported by a hinge mechanism with respect to the document reading unit and is configured to be openable and closable with respect to the document reading unit. <0(000013> When closing the ADF relative to the document scanning unit, it is preferable that the pressure plate that presses the document against the fixed reading glass, or the abutment parts that abut against both ends in the width direction of the flowing reading glass to form the document transport path, are pressed parallel to the surface of those glasses. Furthermore, when performing fixed reading, if a thick document such as a book is set, it is desirable that the closed ADF maintains a certain distance from the fixed reading glass. For this reason, a hinge mechanism consisting of three pivot points and four members that rotate relative to these three pivot points has been proposed (see Patent Document 1). In this Patent Document 1, the entire ADF is configured to be able to be opened and closed relative to the document scanning unit by rotating a fixed end member (33) around a pivot point (f1) relative to a fixed end member (32) fixed to the document scanning unit. In addition, the rotating end member (34) rotates around a pivot point (f2) relative to the fixed end member (33), so that a distance can be maintained between the ADF and the fixed reading glass for thick documents. Furthermore, the upper stay (43) rotates around the pivot point (f3) relative to the rotating end member (34), so that the degree of balance between them can be adjusted when the ADF is closed relative to the document scanning unit.

[0004] Furthermore, since the ADF has a certain amount of weight, a system has been proposed that uses springs (54, 55) to apply torque in the opening and closing direction when opening and closing the ADF relative to the document scanning unit (see Patent Document 2). In other words, such torque-applying springs can improve the operability of opening and closing the ADF by applying a large torque in the opening direction against the weight of the ADF itself. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 3917097 [Patent Document 2] Patent No. 5640303 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Incidentally, in recent years, in order to reduce the weight and cost of ADFs, there have been considerations to construct the ADF frame from resin or thin metal parts, but this tends to reduce the rigidity of the ADF. When the rigidity of the ADF decreases, when closing the ADF relative to the image reading unit, the front end opposite the hinge mechanism (the front side of the image forming apparatus) sags down, and the front end of the ADF comes into contact with it. In this case, if a torque spring is provided to apply torque in the opening and closing direction of the ADF as described above, the biasing force of the spring will generate torque that causes the back side of the ADF (the side closer to the hinge) to lift up, and the ADF's balance cannot be maintained as is.

[0007] Furthermore, the ADF described in Patent Document 2 is provided with an adjustment screw (44) for adjusting the balance when the ADF is closed. However, adjusting the balance with such an adjustment screw has the problem that adjustment is required every time the ADF deforms due to aging or changes in ambient temperature.

[0008] Therefore, it is conceivable to install an equalizing spring that biases the rear of the ADF toward the image reading unit (i.e., downward) to adjust the balance (hereinafter, this adjustment of balance will also be called "equalization"). This allows the system to be configured so that even if the rigidity of the ADF is low and it flexes, and the rear of the ADF tries to lift up due to the torque-applying spring, the equalizing spring will press the rear of the ADF against the image reading unit, automatically performing equalization.

[0009] However, the equalizing spring that presses the rear side of the ADF downwards requires a certain amount of biasing force because the torque-applying spring that applies torque to counteract the weight of the ADF has a large biasing force. If such an equalizing spring is placed at the top of the hinge mechanism to direct the biasing force downwards, there is a problem that the vertical dimension of the hinge mechanism will become excessively large.

[0010] Therefore, the present invention ,above It is possible to make it more compact in the downward direction. Hinge mechanism, image The objective is to provide a reading device and an image forming apparatus. [Means for solving the problem]

[0011] One aspect of the present invention is , painting For the image reading unit Tehara A hinge mechanism that supports the manuscript transport unit so that it can be opened and closed. And, A first member fixed to the image reading unit, a first shaft supported by the first member, a second member that rotates relative to the first member about the first shaft, and a second shaft positioned parallel to the first shaft at a different position and supported by the second member, It has a pair of first side plates and a first top plate connected to the top of the pair of first side plates, A third member that rotates relative to the second member about the second axis, and a third axis that is positioned parallel to the second axis at a different position and supported by the third member, It has a pair of second side plates and a second top plate connected to the top of the pair of second side plates, The document transport unit is fixed ,before A fourth member that rotates relative to the third member around the third axis and ,before Document transport unit with respect to the image reading unit A first biasing unit having a first spring that applies torque in the opening direction, The fourth member rotates relative to the third member around the third axis, It has a second biasing unit having a second spring that applies torque, and the A pair of second side plates The third axis The second top plate is positioned outside the pair of first side plates in the axial direction, and is positioned above the first top plate. The second spring is in the axial direction of the third shaft of the fourth member. a pair The 2 Characterized by being positioned outside the side panel. Hinge mechanism That is the case. [Effects of the Invention]

[0012] According to the present invention, the hinge mechanism can be made more compact in the vertical direction. [Brief explanation of the drawing]

[0013] [Figure 1](a) is an overall schematic diagram showing the printer according to the present embodiment, and (b) is a schematic diagram showing the image forming engine. [Figure 2] It is a perspective view showing an image reading device in a state where the ADF according to the present embodiment is open. [Figure 3] (a) is a schematic cross-sectional view showing a state where the ADF is closed without being bent. (b) is a schematic cross-sectional view showing a state where the ADF is bent and the front abutting portion abuts against the image reading unit. (c) is a schematic cross-sectional view showing a state where the ADF is bent and both the front abutting portion and the rear abutting portion abut against the image reading unit. [Figure 4] It is an exploded perspective view showing the hinge mechanism according to the present embodiment. [Figure 5] It is a cross-sectional view showing the hinge mechanism according to the present embodiment. [Figure 6] It is a diagram showing the relationship between the moment and torque with respect to the opening / closing angle by the hinge mechanism according to the present embodiment. [Figure 7] (a) is a side view showing the hinge mechanism in a state where the ADF is closed without being bent. (b) is a side view showing the hinge mechanism in a state where the ADF is bent and the front abutting portion abuts against the image reading unit. (c) is a side view showing the hinge mechanism in a state where the ADF is bent and both the front abutting portion and the rear abutting portion abut against the image reading unit. [Figure 8] (a) is a schematic cross-sectional view showing a document reading device in a state where a thick document is set on the platen glass and the hinge torque is opened at a large angle. (b) is a side view showing the hinge mechanism in the state of Fig. 8(a). (c) is a cross-sectional view showing the hinge mechanism in the state of Fig. 8(a). <......<......(a) is a schematic cross-sectional view showing a document reading device in a state where a thick document is set on the platen glass and the ADF is closed. (b) is a side view showing the hinge mechanism in the state of Fig. 9(a). (c) is a cross-sectional view showing the hinge mechanism in the state of Fig. 9(a).

Embodiments for Carrying Out the Invention

[0014] [Overall structure] The following description of this embodiment will be illustrated with reference to the figures. The printer 100, which serves as an image forming apparatus according to this embodiment, is an electrophotographic laser beam printer. As shown in Figure 1(a), the printer 100 comprises a printer body 70 and a document reading device 10 mounted on top of the printer body 70. In the following description, "sheet" includes not only plain paper but also special papers such as cardboard and coated paper, recording materials in special shapes such as envelopes and index paper, and plastic films and cloths for overhead projectors, and the original document is also an example of a sheet.

[0015] The printer body 70 has an image forming engine 60 inside as an image forming unit. As shown in Figure 1(b), the image forming engine 60 includes an image forming unit PU as an electrophotographic image forming means and a fixing device 67. When a command is given to start the image forming operation, the photosensitive drum 61, which is a photoreceptor, rotates, and the drum surface is uniformly charged by the charging device 62. Then, the exposure device 63 modulates and outputs laser light based on image data transmitted from the document reading device 10 or an external computer as an image reading means, and scans the surface of the photosensitive drum 61 to form an electrostatic latent image. This electrostatic latent image is visualized (developed) by toner supplied from the developing device 64 to become a toner image.

[0016] In parallel with this image forming operation, a feeding operation is performed to feed a sheet loaded in a cassette or manual feed tray (not shown) toward the image forming engine 60. The fed sheet is transported in accordance with the progress of the image forming operation by the image forming unit PU. The toner image carried on the photosensitive drum 61 is then transferred to the sheet by the transfer roller 65. Toner remaining on the photosensitive drum 61 after the toner image transfer is collected by the cleaning device 66. The sheet on which the unfixed toner image has been transferred is passed to the fixing device 67, where it is held between a pair of rollers and heated and pressurized. The sheet on which the toner has melted and fixed and the image has been fixed is discharged by a discharge means such as a pair of discharge rollers.

[0017] [Document scanning device] Next, the document scanning device 10 will be described in detail. As shown in Figure 1(a), the document scanning device 10 includes an ADF (Automatic Document Feeder) 20 that feeds documents loaded on a document tray 121 and discharges them to an output tray 122, and an image scanning unit 40 that scans the documents scanned by the ADF 20. That is, the ADF 20 transports a sheet of paper as the document to the image scanning unit 40. The image scanning unit 40 has a scanning section 30 that scans the image on the surface of the document. As will be described in more detail later, the ADF 20 is rotatably supported relative to the image scanning unit 40 by a hinge mechanism 3 (see Figure 2) so that the platen glass 201 and document glass 203, which are light-transmitting members, can be opened. The document, which is an example of a sheet, may be blank paper, or it may have an image formed on one or both sides.

[0018] The ADF20 includes a pickup roller 101, a separation drive roller 102 and a separation driven roller 103 which constitute a separation roller pair, a registration roller pair 104, a transport roller pair 105, 106, 108, and a discharge roller pair 109. The ADF20 is also equipped with a reading unit 29 for reading the image on the back side of the document.

[0019] On the other hand, the image reading unit 40 includes a platen glass 201, a jump platform 202, a document glass 203, and a reading unit 30 for reading the surface of a document.

[0020] The document scanner 10 can read images from documents by two modes: a scrolling mode in which documents loaded in the document tray 121 are fed by the ADF 20 while scanning the document image, and a fixed mode in which documents placed on the document glass 203 are scanned. The scrolling mode is selected when a document presence detection sensor (not shown) detects documents loaded in the document tray 121, or when the user explicitly instructs it to be selected via the operation panel of the printer body 70 or the like.

[0021] When the skimming mode is activated, the pickup roller 101 descends and contacts the topmost document set on the document tray 121. The document is then fed by the pickup roller 101 and separated one sheet at a time at the separation nip, which is formed by the separation drive roller 102 and the separation driven roller 103. A torque limiter is positioned in the rotation support structure of the separation driven roller 103, so that the separation driven roller 103 rotates with the separation drive roller 102 when only one document is fed, and does not rotate when two or more documents are fed. This allows the documents to be separated one sheet at a time. Note that a drive in the opposite direction to the sheet feeding direction may also be input to the separation driven roller 103.

[0022] The leading edge of the transported document abuts against the stationary registration roller pair 104, correcting the document's skew. The corrected document is then transported by the registration roller pair 104, and by the transport roller pairs 105, 106, and 108 so as to pass over the surface of the platen glass 201, and then transported to pass over the reading position of the reading unit 29. A platen guide 107 is positioned opposite the platen glass 201, and the platen guide 107 guides the document so that it does not lift off the platen glass 201 as it passes over it.

[0023] The image on the front of the document is read by the reading unit 30 via the platen glass 201, and the image on the back of the document is read by the reading unit 29. The image information converted photoelectrically by the light-receiving elements of line sensors (not shown) in the reading units 30 and 29 is transferred to the control unit 80 (see Figure 1(a)). The document that has passed through the platen glass 201 is then guided by the jump ramp 202 to the transport roller pair 108, passes through the reading unit 29, and is discharged into the discharge tray 122 by the discharge roller pair 109.

[0024] On the other hand, the fixed reading mode is selected when the device detects a document placed on the document glass 203 or when the user explicitly instructs it to be selected via the operation panel of the printer body 70 or the like. In this case, the document on the document glass 203 does not move, and the reading unit 30 moves along the document glass 203 to scan the document. Similarly, the image information converted photoelectrically by the light-receiving element of the line sensor (not shown) of the reading unit 30 is transferred to the control unit 80 (see Figure 1(a)).

[0025] [Positional relationship between ADF and image reading unit] Next, the arrangement of the hinge mechanism 3 and the configuration of the abutment portion 21 and pressure plate 22, which are provided on the ADF 20 and come into contact with the image reading unit 40 when the ADF 20 is closed, will be explained with reference to Figure 2. Figure 2 is a perspective view showing the image reading device according to this embodiment in the open state of the ADF.

[0026] As shown in Figure 2, the document scanning device 10 according to this embodiment has left and right hinge mechanisms 3L and 3R (hereinafter simply referred to as "hinge mechanism 3" when distinction is unnecessary) installed on the image scanning unit 40 to support the ADF 20 so that it can be opened and closed. These left and right hinge mechanisms 3L and 3R are installed on the image scanning unit 40 at two different positions in the X direction, which is the left-right direction of the printer 100. These left and right hinge mechanisms 3L and 3R are designed to be of different sizes to accommodate the difference in weight in the left-right direction of the ADF 20.

[0027] The abutment portion 21 has a first abutment portion 21a that abuts the front end of the platen glass 201 in the Y direction, which is the front-to-back direction of the printer 100, when the ADF 20 is closed. The abutment portion 21 also has a second abutment portion 21b that abuts the rear end of the platen glass 201 in the Y direction, which is the front-to-back direction of the printer 100, when the ADF 20 is closed. The abutment portion 21a is positioned further from the hinge mechanism 3 than the area of ​​the transport path where the sheets are transported, in the width direction perpendicular to the sheet transport direction. On the other hand, the abutment portion 21b is positioned closer to the hinge mechanism 3 than the area of ​​the transport path where the sheets are transported, in the width direction. As these abutment portions 21a and 21b come into contact with both ends of the platen glass 201, a transport path is formed between the platen glass 201 and the jump ramp 202 (see Figure 1(a)) and the platen guide 107 for the document to pass through in the above-described scrolling mode.

[0028] In other words, the platen glass 201 and the jump ramp 202, together with the platen guide 107 of the ADF 20, are configured as part of the transport guide that guides the document. However, while the transport guides for other parts of the ADF 20 that guide the document are configured within the same ADF 20, the platen glass 201 and the jump ramp 202 are components on the image reading unit 40 side. Therefore, by having these abutment parts 21a and 21b contact both ends of the platen glass 201, the relative position between the image reading unit 40 and the ADF 20 is appropriately maintained, and consistency is maintained between the transport paths of other parts of the ADF 20 and the transport path on the platen glass 201.

[0029] Furthermore, these abutment portions 21a and 21b may also contact the frame portion 205 (see Figure 3(a)) surrounding the platen glass 201. Due to the effects of part tolerances and, as will be described in detail later, adjustment of balance (equalization), these abutment portions 21a and 21b may come into contact with the frame portion 205. However, the surface of the frame portion 205 is formed to be substantially coplanar with the surface of the platen glass 201, so even if the abutment portions 21a and 21b come into contact with the frame portion 205, it is equivalent to if they came into contact with the surface of the platen glass 201. In other words, even if the abutment portions 21a and 21b come into contact with the frame portion 205, the relative position between the image reading unit 40 and the ADF 20 is appropriately maintained, and consistency with the transport path of other parts is preserved.

[0030] Furthermore, the ADF 20 is provided with a pressure plate 22 that is pressed against the document glass 203 when the ADF 20 is closed. The pressure plate 22 is rectangular in shape, having a front edge 22a that is in front of the printer 100, a rear edge 22b that is behind, a left edge 22c that is to the left, and a right edge 22d that is to the right. On the other hand, the document glass 203 is provided with a vertical size indicator 206 and a horizontal size indicator 207 that indicate the size of the document to be placed. When the ADF 20 is closed, the pressure plate 22 is positioned so that the left edge 22c does not overlap with the vertical size indicator 206 and is as close as possible with no gap, and the rear edge 22b does not overlap with the horizontal size indicator 207 and is as close as possible with no gap. In more detail, when the abutment of the stopper part 21b is adjusted by equalization, which will be described later, the rear edge 22b will be adjusted to be close to the horizontal size indicator 207.

[0031] [Configuration of hinge mechanism 3] Next, the configuration of the hinge mechanism 3 according to this embodiment will be explained using Figures 4 to 6. Figure 4 is an exploded perspective view showing the hinge mechanism according to this embodiment. Figure 5 is a cross-sectional view showing the hinge mechanism according to this embodiment. Figure 6 is a diagram showing the relationship between moment and torque with respect to the opening and closing angle of the hinge mechanism according to this embodiment. For the purpose of explaining the structure of the hinge mechanism 3, the directions used will be those of the printer 100, assuming it is fixed to the printer 100, and will be described using the left-right direction (X direction), front-back direction (Y direction), and up-down direction (Z direction).

[0032] As shown in Figures 4 and 5, the hinge mechanism 3 broadly comprises a fixed member 31 as a first member, an opening / closing member 32 as a second member, a first rotating member 33 as a third member, and a second rotating member 34 as a fourth member. The hinge mechanism 3 also comprises a hinge rotation axis 35 as a first axis supported by the fixed member 31, a book rotation axis 36 as a second axis supported by the opening / closing member 32, and an equalization axis 38 as a third axis supported by the first rotating member 33. Furthermore, as shown in Figure 5, the hinge mechanism 3 has a first biasing unit F1 having a spring 53 as a first spring that applies torque in the direction of opening the ADF 20 according to the rotation angle of the ADF 20 relative to the image reading unit 40. Furthermore, the fixed member 31 has a cam pin 31A as a one-side pressure receiving part that receives the biasing force of the spring 53 to one side, and the first rotating member 33 has a lift shaft 37 as a other-side pressure receiving part that receives the biasing force of the spring 53 to the other side. The hinge mechanism 3 has a second biasing part F2 that has a second spring and a third spring 39 that applies torque to the second rotating member 34 in a direction in which the abutment part 21 and pressure plate 22 are parallel to the surface of the platen glass 201.

[0033] In detail, as shown in Figure 5, the fixing member 31 has a bottom plate 31c fixed to the image reading unit 40, a pair of side plates 31d formed upward from the bottom plate 31c, and a back plate 31e similarly formed upward from the bottom plate 31c. That is, the fixing member 31 is formed in a box shape with openings at the top and front by these bottom plate 31c, side plates 31d, and back plate 31e. Furthermore, through holes 31a and 31b are formed through the pair of side plates 31d, and the hinge pivot shaft 35 is inserted into and supported in the through hole 31a with its axial direction being left-right. In addition, a cam pin 31A is fitted into and fixedly supported in the through hole 31b with its longitudinal direction being left-right.

[0034] As shown in Figures 4 and 5, the opening / closing member 32 has a top plate 32c and a pair of side plates 32d formed downward from the top plate 32c. That is, the opening / closing member 32 is formed in a U-shape so as to cover the fixing member 31 from above. The pair of side plates 32d have through holes 32a on the rear side and 32b on the front side. The hinge pivot shaft 35, which is inserted into the through hole 31a of the fixing member 31, is fitted into the through hole 32a so as to straddle the left-right direction and is fixedly supported. Furthermore, the book pivot shaft 36 is inserted into the through hole 32b so as to have its axial direction in the left-right direction and is supported. Therefore, the book pivot shaft 36 is positioned parallel to the hinge pivot shaft 35 at a different position. The opening / closing member 32 is configured to be rotatable relative to the fixing member 31 with the center CT1 of the hinge pivot shaft 35 as the pivot point.

[0035] The first rotating member 33 is as shown in Figures 4 and 5. 1 A top plate 33c as a tabletop, and a pair of plates formed downward from the top plate 33c. 1It has a side plate 33d as a side plate. In other words, the first rotating member 33 is arranged on a plane perpendicular to the book rotation axis 36, the lift axis 37, and the equalizing axis 38, and has a plate-shaped side plate 33d that engages with the book rotation axis 36, the lift axis 37, and the equalizing axis 38. The first rotating member 33 also has a plate-shaped top plate 33c arranged on a plane perpendicular to the side plate 33d. That is, the first rotating member 33 is formed in a U shape so as to cover the opening / closing member 32 from above. Furthermore, the pair of side plates 33d have through holes 33a, a through hole 33b on the front side and a through hole 33e on the lower side. The book rotation axis 36, which is inserted into the through hole 32a of the opening / closing member 32, is fitted into the through hole 33a so as to straddle the left and right sides and is fixedly supported. Furthermore, the equalizing shaft 38 is inserted into and supported in the through hole 33b with its axial direction being left-right. Similarly, the lift shaft 37 is inserted into and supported in the through hole 33e with its axial direction being left-right. Therefore, the lift shaft 37 and the equalizing shaft 38 are arranged parallel to the book rotation shaft 36 at different positions. The first rotating member 33 is configured to be rotatable with respect to the opening / closing member 32, with the center CT2 of the book rotation shaft 36 as the pivot point.

[0036] Furthermore, each of the pair of side plates 33d in the first rotating member 33 has a spring support portion 33f formed thereon, which is an upper pressure receiving portion that extends outward from the side plate 33d in the axial direction of the equalizing shaft 38. In addition, the tip portion 33g of the spring support portion 33f is bent downward. The upper end 39a of the spring 39 of the second biasing member F2, which will be described in more detail later, engages with this spring support portion 33f, thereby allowing the spring support portion 33f to receive the biasing force of the spring 39. Moreover, the contact restricting portion 34k of the second rotating member 34, which will be described later later, is configured to contact the spring support portion 33f from below, that is, the contact restricting portion 34k is configured to contact or separate from the second rotating member 34 as the second rotating member 34 rotates.

[0037] The second rotating member 34 is as shown in Figures 4 and 5. 2It has a top plate 34c as a top plate and a pair of side plates 34d formed downward from the top plate 34c. These pair of side plates 34d are arranged to face each other. In other words, in the left-right direction of the printer 100, the left portion of the second rotating member 34 2 The side plate 34d(L) as a side plate is located in the right portion of the second rotating member 34. 2 Side panels 34d(R) are positioned on each side. In the following explanation, when it is not necessary to distinguish between the left and right side panels 34d(L) and side panel 34d(R), they will simply be referred to as side panel 34d.

[0038] In other words, the second rotating member 34 has a pair of plate-shaped side plates 34d arranged on a plane perpendicular to the equalizing axis 38 and engaging with the equalizing axis 38, and a plate-shaped top plate 34c arranged on a plane perpendicular to the pair of side plates 34d. That is, the second rotating member 34 is formed in a U-shape so as to cover the first rotating member 33 from above. Therefore, the second rotating member 34 is positioned such that the top plate 34c is above the top plate 33c of the first rotating member 33.

[0039] Furthermore, a through hole 34a is formed at the front of the pair of side plates 34d, and a relief hole 34b is formed at the rear. The book pivot shaft 36, which is inserted into the through hole 32a of the opening / closing member 32 and the through hole 33a of the first pivot member 33, and the lift shaft 37, which is inserted into the through hole 33e of the first pivot member 33, are positioned to pass through the relief hole 34b so as not to interfere with each other. In addition, the equalizer shaft 38 is fitted and fixedly supported in the through hole 34a, which is located on the opposite side in the front-rear direction from the hinge pivot shaft 35 relative to the book pivot shaft 36, so as to straddle it in the left-right direction. The second pivot member 34 is configured to be rotatable relative to the first pivot member 33 with the center CT3 of the equalizer shaft 38 as the pivot point.

[0040] Furthermore, the side plate 34d is integrally bent and formed with a first support plate portion 34e having screw holes 34f and a second support plate portion 34g having two screw holes 34h. Screws (not shown) are screwed into the screw holes 34f and 34h of the first support plate portion 34e and the second support plate portion 34g, thereby fixing the case 20C of the ADF 20 or a frame (not shown). As a result, the second rotating member 34 and the ADF 20 are integrated, and the ADF 20 is opened and closed by the angle of the second rotating member 34.

[0041] Furthermore, each of the pair of second support plate portions 34g in the second rotating member 34 has a bent spring support portion 34i that extends outward from the side plate 34d in the axial direction of the equalizing shaft 38, serving as a lower end pressure receiving portion. In addition, a tip portion 34j is formed at the tip of the spring support portion 34i, facing upward. The lower end 39b of the spring 39 of the second biasing portion F2, which will be described in more detail later, engages with this spring support portion 34i, thereby allowing the spring support portion 34i to receive the biasing force of the spring 39. Also, the rear portion of the side plate 34d of the second rotating member 34 lacks a top plate 34c, thus forming the contact restricting portion 34k. The contact restriction portion 34k comes into contact with the spring support portion 33f when the second rotating member 34 rotates by a predetermined angle An5 from the mounted position in the direction that the ADF 20 closes relative to the image reading unit 40, around the equalization axis 38 relative to the first rotating member 33. This restricts the second rotating member 34 from rotating further relative to the first rotating member 33. Furthermore, the contact restriction portion 34k separates from the spring support portion 33f when the rotation of the second rotating member 34 around the equalization axis 38 is less than the predetermined angle An5 relative to the first rotating member 33. This allows relative rotation between the first rotating member 33 and the second rotating member 34.

[0042] The second biasing unit F2 described above is configured with a pair of springs 39, the upper end 39a of which is supported by the spring support portion 33f of the first rotating member 33, and the lower end 39b of which is supported by the spring support portion 34i of the second rotating member 34. This pair of springs 39 is positioned outside the side plate 34d of the second rotating member 34 in the axial direction of the equalizing shaft 38. In other words, in the left-right direction of the printer 100, the spring 39(L) as the second spring is positioned to the left of the side plate 34d(L) on the left side of the second rotating member 34. Also, the spring 39(R) as the third spring is positioned to the right of the side plate 34d(R) on the right side of the second rotating member 34. Furthermore, these springs 39 are positioned below the top plate 33c of the first rotating member 33 and above the second support plate portion 34g, which is the lower end of the side plate 34d of the second rotating member 34, when the ADF 20 is closed relative to the image reading unit 40. In the following description, when it is not necessary to distinguish between the left and right springs, they will simply be referred to as spring 39.

[0043] On the other hand, the first biasing unit F1 is composed of a spring 53, which is a coil spring as the first spring, and a first slider 51 as the first support member and a second slider 52 as the second support member, which are positioned at both ends of the spring 53, respectively. The first slider 51 abuts against and supports one end 53a of the spring 53 and is slidably positioned relative to the top plate 32c and side plate 32d (see Figure 4) of the opening / closing member 32. In addition, the end face 51a of the first slider 51 opposite to the spring 53 abuts against and engages with the cam pin 31A. In other words, the biasing force of the spring 53 toward one side is received by the fixing member 31 via the cam pin 31A.

[0044] Similarly, the second slider 52 is supported by contacting the other end 53b of the spring 53 and is slidably positioned relative to the top plate 32c and side plate 32d (see Figure 4) of the opening / closing member 32. Furthermore, the end face 52a of the second slider 52 opposite to the spring 53 is in contact with the lift shaft 37 while engaging with it. In other words, the biasing force of the spring 53 toward the other side is absorbed by the lift shaft 37.

[0045] Here, we will explain how torque is applied by the first biasing unit F1 configured in this way. As the ADF20 opens and closes, the opening / closing member 32 mainly opens and closes relative to the fixed member 31. While the cam pin 31A is fixed to the fixed member 31, the first slider 51 rotates together with the opening / closing member 32 around the center CT1 of the hinge pivot shaft 35 as a pivot point. As a result, the spring 53 expands and contracts according to the shape of the end face 51a that contacts and engages with the cam pin 31A. That is, since the book pivot shaft 36 is positioned relative to the opening / closing member 32, the biasing force of the spring 53 applied to the lift shaft 37, which is rotatable around the center CT2 of the book pivot shaft 36, changes.

[0046] The opening / closing angle An1 (see Figure 5) is the angle of rotation of the opening / closing member 32 relative to the fixed member 31 with the hinge pivot axis 35 as the fulcrum. Figure 6 shows the relationship between the magnitude of the moment M in the closing direction of the ADF 20 relative to the image reading unit 40 and the magnitude of the torque T applied in the opening direction by the first biasing unit F1, with respect to this opening / closing angle An1. In other words, the torque T from the first biasing unit F1 has the characteristic of peaking when this opening / closing angle An1 is an angle An1a (for example, 10 to 20 degrees).

[0047] Therefore, when the opening / closing angle An1 is 10 degrees or less, that is, when the ADF20 is closed to 10 degrees or less, the moment M due to the weight of the ADF20 becomes greater than the torque T due to the first biasing part F1 of the hinge mechanism 3, and it is configured to close by its own weight. Also, when the opening / closing angle An1 is 20 degrees or more, the torque T due to the first biasing part F1 of the hinge mechanism 3 becomes equal to or greater than the moment M due to its own weight, and the ADF20 can be kept open, making it easy to open and close the ADF20.

[0048] [Regarding deflection in relation to the rigidity of the ADF] Next, the deflection of the ADF 20 corresponding to the rigidity of the ADF 20 that occurs when opening and closing the ADF 20, and the contact state between the abutment portion 21 and the platen glass 201 (including the frame portion 205) will be explained using Figures 3(a), 3(b), and 3(c). Figure 3(a) is a schematic cross-sectional view showing the state in which the ADF is closed without deflection. Figure 3(b) is a schematic cross-sectional view showing the state in which the ADF is deflected and the front abutment portion is contacting the image reading unit. Figure 3(c) is a schematic cross-sectional view showing the state in which the ADF is deflected and the front abutment portion and the rear abutment portion are contacting the image reading unit. As mentioned above, the abutment portion 21 may also contact the frame portion 205, but in the following explanation, it will be described as contacting the platen glass 201, as this is equivalent to contacting the platen glass 201.

[0049] As shown in Figure 3(a), if the frame structure of the ADF20 (not shown) is highly rigid and the case 20C of the ADF20 does not flex, then when the ADF20 is closed, the abutment portions 21a and 21b will abut the platen glass 201 in equilibrium. However, as shown in Figure 3(b), if the ADF20 is constructed with a resin frame structure for weight reduction or cost reduction, for example, the rigidity is low and the case 20C will flex under its own weight. Therefore, when the ADF20 is closed relative to the image reading unit 40, the front of the ADF20 sags, and the front abutment portion 21a abuts the platen glass 201 before the rear abutment portion 21b.

[0050] Furthermore, as described above, the hinge mechanism 3 is subjected to a torque T (see Figure 6) by the first biasing part F1 in the direction that opens the ADF 20, making it easier to open and close the ADF 20, and the force Ft due to this torque T acts on the lift shaft 37. Therefore, for example, if the second biasing part F2 were absent, even if the ADF 20 were closed, the abutment part 21b would not abut against the platen glass 201 and would remain floating.

[0051] In the hinge mechanism 3 according to this embodiment, as shown in Figure 3(c), the second biasing part F2 described above is provided, so that the biasing force of the spring 39 presses the spring support part 34i (see Figure 4) of the second rotating member 34 against the first rotating member 33 with a force Fs. As a result, the rear abutment part 21b can abut against the platen glass 201, that is, the balance between the front abutment part 21a and the rear abutment part 21b is adjusted, and a document transport path is formed accurately between the platen glass 201 and the ADF 20. In this embodiment, this adjustment of balance is called equalization, and the details of the equalization of this hinge mechanism 3 will be explained below with reference to Figure 7.

[0052] [Equalization of the hinge mechanism] Next, the equalization of the abutment portions 21a and 21b against the platen glass 201 by the hinge mechanism 3 will be explained using Figures 7(a), 7(b), and 7(c), with reference to Figures 3(a), 3(b), and 3(c). Figure 7(a) is a side view showing the hinge mechanism when the ADF is closed without bending. Figure 7(b) is a side view showing the hinge mechanism when the ADF is bent and the front abutment portion is in contact with the image reading unit. Figure 7(c) is a side view showing the hinge mechanism when the ADF is bent and both the front abutment portion and the rear abutment portion are in contact with the image reading unit.

[0053] Furthermore, the angles, dashed lines, and positions of each axis and abutment part described using Figures 7(a), 7(b), and 7(c) are explained as being viewed from the axial direction (X direction) of the hinge rotation axis 35, book rotation axis 36, lift axis 37, and equalization axis 38.

[0054] As the ADF20 is closed from the open position, the opening / closing angle An1 between the reference plane H31 on which the fixing member 31 is installed and the bottom surface H32 of the opening / closing member 32 decreases, as shown in Figure 7(a). The bottom surface H32 is parallel to the center of the top plate 32c (see Figure 4) and the spring 53 (see Figure 5).

[0055] Here, Figure 7(a) shows the hinge mechanism 3 in the ideal state where the ADF 20 is closed to the image reading unit 40, as shown in Figure 3(a), with the case 20C of the ADF 20 not bending. As shown in Figure 7(a), when the ADF 20 is ideally closed, the bottom surface H32 of the opening / closing member 32 is positioned parallel to the reference plane H31. Then, the second rotating member 34 to which the ADF 20 is fixed is also positioned parallel, and the rear abutment portion 21b abuts against the platen glass 201. In this state, a gap d1 is formed on the rear side between the second rotating member 34 and the first rotating member 33.

[0056] Furthermore, the tip 22ba of the abutment portion 21b that contacts the platen glass 201 constitutes the end of the abutment portions 21a and 22b that contact the image reading unit 40, on the side of the hinge mechanism 3.

[0057] Due to the structure of the hinge mechanism 3 described above, parts of the hinge mechanism 3 other than the fixing member 31, such as the abutment portion 21b, and the ADF 20, rotate around the hinge pivot axis 35. Therefore, the tip 22ba of the abutment portion 21b rotates roughly along a rotation trajectory D35 with a radius centered on the hinge pivot axis 35. In addition, the second rotating member 34 rotates around the equalizing axis 38. Therefore, the rear abutment portion 21b provided on the ADF 20 fixed to the second rotating member 34 also rotates along a rotation trajectory D38 with a radius centered on the equalizing axis 38.

[0058] As described above, due to the low rigidity of the ADF20 frame, the front (-Y direction side) of the ADF20 sags, as shown in Figure 3(c). As a result, the front abutment portion 21a contacts the platen glass 201 first, and at this moment, the rear abutment portion 21b is floating above the platen glass 201.

[0059] In this state, the hinge mechanism 3 is in the state shown in Figure 7(b), the opening / closing member 32 is slightly open at an opening / closing angle An1b compared to the ideal state shown in Figure 7(a), and the abutment portion 21b is floating away from the platen glass 201 at a distance d2.

[0060] Furthermore, in this state, as shown in Figure 3(b), the weight W of the ADF 20 acts at the center of gravity, which is at a distance yw1 from the front abutment 21a, thereby acting a moment in the direction of closing the ADF 20. In addition to this, a force Ft due to the torque in the direction of opening the ADF 20 by the first biasing part F1 of the hinge mechanism 3 acts on the equalizing shaft 38. The equalizing shaft 38 is assumed to be at a distance yt1 from the front abutment 21a. Then, as described above, a force Fs that presses the second rotating member 34 toward the first rotating member 33 by the spring 39 in the second biasing part F2 acts at a distance ys1 from the front abutment 21a.

[0061] The condition under which the sum of the force Fs due to spring 39 and the moment due to the weight W of ADF20 is greater than the moment generated by the force Ft due to the torque of the first biasing part F1 of hinge mechanism 3 is shown by the following equation (1). Fs·ys1+W·yw1>Ft·yt1 (1)

[0062] If the condition in equation (1) is met, the equalizer shaft 38, on which the torque T of the first biasing unit F1 is generated, is pushed down, that is, the opening / closing member 32 is closed, and the rear abutment portion 21b of the ADF 20 is lowered so as to come into contact with the platen glass 201.

[0063] Specifically, in the hinge mechanism 3 shown in Figure 7(b), the equalizing shaft 38 rotates clockwise around the hinge pivot shaft 35 in the figure, together with the opening / closing member 32, the first rotating member 33, and the second rotating member 34. Furthermore, the second rotating member 34 is pressed by the spring 39 and rotates counterclockwise around the equalizing shaft 38 towards the first rotating member 33, transitioning to the state shown in Figure 7(c). As a result, in the state shown in Figure 7(c), the gap d1 on the rear side between the second rotating member 34 and the first rotating member 33 (see Figure 7(a)) becomes smaller. In other words, in the state shown in Figure 7(c), the angle An2 between the top plate 33c of the first rotating member 33 and the top plate 34c of the second rotating member 34 rotates from a state where the rear side is acute (see Figure 7(b)) to a state where the front side is acute.

[0064] In other words, the abutment portion 21b moves relative to the platen glass 201 due to the rotation of the second rotating member 34 with respect to the first rotating member 33 around the equalizing axis 38. As a result, the imaginary line L2 connecting the center of the equalizing axis 38 and the tip 22ba of the abutment portion 21b rotates by an angle ΔAn4 from the angle An4 formed by the perpendicular to the reference plane H31 and the imaginary line L2.

[0065] On the other hand, the opening / closing member 32 and the first rotating member 33 rotate downwards with respect to the fixed member 31, with the front side having the abutment portion 21b facing downwards around the hinge rotation axis 35. That is, the imaginary line L1 connecting the center of the hinge rotation axis 35 and the tip 22ba of the abutment portion 21b rotates by an angle ΔAn3 from the angle An3 that the imaginary line L1 makes with the perpendicular to the reference plane H31. As a result, the tip of the imaginary line L1 overlaps the reference plane H31 downwards by a distance d3.

[0066] As described above, during equalization as shown in Figure 7(c), the opening / closing member 32 and the first rotating member 33 are combined with the rotation of the second rotating member 34 with respect to the first rotating member 33 around the equalization axis 38, relative to the fixed member 31 around the hinge rotation axis 35. This ensures that the tip 22ba of the abutment portion 21b is in contact with the platen glass 201 without floating.

[0067] The angle ΔAn3 at which the virtual line L1 rotates to overlap below the reference plane H31 is determined by the position of the equalization axis 38 in the hinge mechanism 3. That is, the smaller the angle An4 formed by the virtual line L2 connecting the tip 21ba of the abutment portion 21b and the center of the equalization axis 38, and the perpendicular to the reference plane H31, the smaller the amount of variation in angle ΔAn3.

[0068] In the hinge mechanism 3 according to this embodiment, the equalizer shaft 38 is positioned on the opposite side of the hinge pivot shaft 35 from the book pivot shaft 36, and is positioned particularly in front of the book pivot shaft 36 (in the Y direction) and close to the abutment portion 21b. As a result, during equalization, the angle ΔAn4 in which the angle An4 changes is extremely small compared to the angle ΔAn3 in which the angle An3 changes. Therefore, the reduction in torque T caused by the first biasing portion F1 due to the rotation of the opening / closing member 32 during equalization is negligible and has almost no effect.

[0069] [Book Equalize] Next, we will explain the case where the ADF 20 is closed and book equalization is performed when a thick document Da, such as a dictionary, is placed on the document glass 203 and the fixed reading mode is executed, using Figures 8(a), 8(b), 8(c), 9(a), 9(b), and 9(c). Figure 8(a) is a schematic cross-sectional view showing the document reader with a thick document set on the document glass and the hinge open at an angle with a large torque. Figure 8(b) is a side view showing the hinge mechanism in the state shown in Figure 8(a). Figure 8(c) is a cross-sectional view showing the hinge mechanism in the state shown in Figure 8(a). Figure 9(a) is a schematic cross-sectional view showing the document reader with a thick document set on the document glass and the ADF closed. Figure 9(b) is a side view showing the hinge mechanism in the state shown in Figure 9(a). Figure 9(c) is a cross-sectional view showing the hinge mechanism in the state shown in Figure 9(a).

[0070] Book equalization is the process shown in Figure 8(a) where the user applies a downward operating force FU to the front portion of the ADF 20, causing the ADF 20 to rotate clockwise around the book rotation axis 36, and adjusting the ADF 20 to balance as shown in Figure 9(a). The following describes the operation during book equalization.

[0071] In fixed reading mode, a document placed on the document glass 203 can be read by moving the reading unit 30 (see Figure 1) in the left-right direction (X direction) while scanning in the Y direction. For particularly thin documents, the ADF 20 can be closed relative to the image reading unit 40, thereby pressing the document against the document glass 203 with the pressure plate 22 of the ADF 20.

[0072] However, as shown in Figure 8(a), if the document Da placed on the document glass 203 is a thick book such as a dictionary, the open side will be facing the document glass 203. In this case, the gutter area in the center of the open page tends to lift up, making it difficult to focus or causing it to become dark. Therefore, it is preferable to hold the ADF 20 parallel to the document glass 203 and press down on this area in particular.

[0073] Figure 8(b) shows the hinge mechanism 3 when the ADF20 is in the state shown in Figure 8(a). The opening and closing angle of this hinge mechanism 3 is near the angle An1a in Figure 6, and the torque T in the direction of opening the ADF20 by the first biasing part F1 is in the largest region, while the moment M due to the weight of the ADF20 is slightly lower compared to the closed state.

[0074] The force Fs exerted by the spring 39 of the second biasing unit F2 and the weight W of the ADF2 are in a seesaw-like state with respect to the lift shaft 37 (see Figure 3(c)). Therefore, if the force Fs exerted by the spring 39 is stronger, the second rotating member 34 rotates relative to the first rotating member 33 around the equalizing shaft 38.

[0075] Figure 8(c) is a cross-sectional view of the hinge mechanism 3 in the state shown in Figures 8(a) and 8(b). The first rotating member 33 is configured to rotate around the book pivot axis 36 as a fulcrum, but in this state, it is pressed by the second slider 52, which is pressed by the spring 53, via the lift axis 37. As a result, a counterclockwise moment acts on the first rotating member 33 in the figure, and the top plate 33c abuts against the top plate 32c of the opening / closing member 32 at its rear end. Also, inside the opening / closing member 32, the first slider 51 of the first biasing part F1 abuts against and engages with the cam pin 31A, and the lift axis 37 abuts against the second slider 52, so the effective length of the spring 53 is length x1.

[0076] At this time, as described above, when the second rotating member 34 is further subjected to the operating force FU, it rotates at a predetermined angle with the equalizing shaft 38 as the pivot point, causing the contact restricting portion 34k to come into contact with the spring support portion 33f. This contact causes the first rotating member 33 and the second rotating member 34 to become one unit, and the operating force FU acts as a moment that presses the second slider 52 and shortens the length of the spring 53 due to the rotation of the lift shaft 37 with the book rotation shaft 36 as the pivot point.

[0077] As a result, the book equalized state is as shown in Figure 9(a). At this time, the entire document Da can be pressed vertically downward against the document glass 203 by the pressure plate 22 of the balanced ADF 20. On the other hand, a strong restoring force from the spring 53 of the first biasing unit F1 acts on the lift shaft 37, so this state cannot be maintained unless the operating force FU is continuously applied.

[0078] Figure 9(b) shows the hinge mechanism 3 when the ADF 20 is in the state shown in Figure 9(a). The opening / closing member 32 is open at an angle An1a with the hinge pivot axis 35 as the fulcrum, but the first rotating member 33 and the second rotating member 34 also rotate clockwise in the figure with the book pivot axis 36 as the fulcrum. This positions the pressure plate 22 of the ADF 20 parallel to the document glass 203, and evenly presses the entire document Da.

[0079] The contact restricting portion 34k of the second rotating member 34 maintains contact with the spring support portion 33f, transmitting the operating force FU applied to the front portion of the ADF 20 from the second rotating member 34 to the first rotating member 33. This compresses and pushes the spring 53 of the first biasing portion F1 by the lift shaft 37, generating a moment that causes the first rotating member 33 and the second rotating member 34 to rotate together clockwise in the figure, with the book rotation shaft 36 as the fulcrum.

[0080] Furthermore, since the contact restricting portion 34k is in contact with the spring support portion 33f, the second rotating member 34 will not rotate clockwise around the equalizing shaft 38 as a pivot point beyond this state, and will not further compress the spring 39 of the second biasing portion F2. As a result, the windings of the spring 39 will not be in close contact with each other, and there will be no risk of the spring 39 sagging.

[0081] Figure 9(c) is a cross-sectional view of the hinge mechanism 3 in the state shown in Figures 9(a) and 9(b). The lift shaft 37 pushes the second slider 52 against the spring 53, and the effective length of the spring 53 becomes a length x2 which is shorter than the length x1 mentioned above. In the state shown in Figure 9(c), the opening and closing angle of the opening / closing member 32 remains at angle An1a, and as shown in Figure 6, the torque T generated by the hinge mechanism 3 is near its maximum. That is, the first slider 51 is almost fully compressed due to its engagement with the cam pin 31A, and in addition, the lift shaft 37 is subjected to an additional biasing force due to the further compression of the spring 53. Therefore, when the first rotating member 33 is rotated relative to the opening / closing member 32 in the direction that the ADF 20 closes, the distance of the spring 53 is shortened via the lift shaft 37, and a torque is applied to the first rotating member 33 in the opposite direction to the closing direction (opening direction).

[0082] [Arrangement of the second biasing unit] Next, the arrangement of the second biasing part F2 of the hinge mechanism 3 according to the embodiment described above will be explained. The second biasing part F2 of the hinge mechanism 3 applies a biasing force to the third rotating member 33 so that the second rotating member 34 rotates in the direction of opening the ADF 20 around the equalization axis 38 (in the direction that the abutment part 21b is lower than the abutment part 21a). Considering the function of such a biasing part F2, it is conceivable to configure it to press the top plate 34c of the second rotating member 34 downward against the top plate 33c of the first rotating member 33. However, if a spring is to be placed between the top plates 33c and 34c in this way, the spring would have to be placed above the top plate 34c because the first biasing part F1 is located inside the hinge mechanism 3. In this case, the vertical size of the hinge mechanism 3 would increase, leading to an overall increase in the size of the ADF 20.

[0083] Furthermore, if a spring is interposed between the top plate 33c and the top plate 34c, there is a risk that the biasing force of the spring may cause the top plates 33c and 34c to flex. If this occurs, the biasing force of the spring will be released, and the amount of rotation of the second rotating member 34 during equalization will decrease, meaning that the amount of adjustment required to abut the abutment portion 21b will decrease. Also, if the thickness of the top plates 33c and 34c is increased to avoid this phenomenon, it will lead to an increase in the size and cost of the hinge mechanism 3.

[0084] Therefore, the pair of springs 39 in the second biasing section F2 of the hinge mechanism 3 according to this embodiment are positioned outside the side plate 34d of the second rotating member 34 in the axial direction of the equalizing shaft 38. This prevents the hinge mechanism 3 from becoming larger in the vertical direction. In addition, since the springs 39 do not press against the top plates 33c and 34c, it is not necessary to increase the thickness of these top plates 33c and 34c, which also prevents the hinge mechanism 3 from becoming larger and helps to prevent cost increases.

[0085] Furthermore, in the hinge mechanism 3 according to this embodiment in particular, the spring 39 is positioned below the top plate 33c of the first rotating member 33 and above the lower end of the side plate 34d of the second rotating member 34, when the ADF 20 is closed relative to the image reading unit 40. As a result, the spring 39 does not protrude above the hinge mechanism 3 and does not interfere with the image reading unit 40, allowing for a compact arrangement in the vertical direction.

[0086] Furthermore, in the hinge mechanism 3 according to this embodiment, the first rotating member 33 has a spring support portion 33f that extends outward from the side plate 33d and engages with the upper end 39a of the spring 39 to receive the biasing force of the spring. Furthermore, the second rotating member 34 has a spring support portion 34i that extends outward from the side plate 34d and engages with the lower end 39b of the spring 39 to receive the biasing force of the spring 39. Therefore, these spring support portions 33f and 34i make it possible to position the spring 39 outside the side plate 34d of the second rotating member 34, and to apply the biasing force of the spring 39 between the first rotating member 33 and the second rotating member 34. Note that these spring support portions 33f and 34i can be easily constructed and cost-reduced by bending them by press working.

[0087] [Possibility of other embodiments] In the embodiment described above, the spring 39 is positioned below the top plate 33c of the first rotating member 33 and above the lower end of the side plate 34d of the second rotating member 34, when the ADF 20 is closed to the image reading unit 40. In other words, the spring 39 is positioned within the overlapping range between the first rotating member 33 and the second rotating member 34 in the vertical direction, as viewed from the axial direction. However, the configuration is not limited to this, and a part of the spring 39 may protrude beyond the vertical range between the first rotating member 33 and the second rotating member 34. That is, if a part of the spring 39 is positioned to overlap between the first rotating member 33 and the second rotating member 34 in the vertical direction, as viewed from the axial direction, the effect of vertical compactness can be obtained.

[0088] Furthermore, in this embodiment, an end face 51a that engages with the cam pin 31A is formed on the first slider 51 of the first biasing unit F1, thereby changing the torque T in the opening direction according to the opening and closing angle of the ADF 20. However, this is not the only method; it is also possible to simply receive the biasing force on one end of the spring 53 and apply a constant torque in the opening direction of the ADF 20. In this case, the first slider 51 and the second slider 52 may be omitted, and the spring 53 may be provided so as to directly contact the fixing member 31 and the lift shaft 37. Also, as a mechanism to change the torque T according to the opening and closing angle, any mechanism is acceptable, such as interposing a cam that rotates according to the opening and closing angle, or any other mechanism that changes the biasing force of the first biasing unit according to the opening and closing angle.

[0089] Furthermore, in this embodiment, a contact restricting portion 34k is formed on the second rotating member 34, and it contacts the spring support portion 33f to transmit the user's operating force in the closing direction of the ADF 20 to the first rotating member 33. However, the embodiment is not limited to this, and any structure is acceptable as long as there is a portion that contacts each other when the second rotating member 34 rotates relative to the first rotating member 33 at a predetermined angle.

[0090] [Summary of this embodiment] [Configuration 1] An image reading unit having a light-transmitting member and a reading unit that reads an image of a document through the light-transmitting member, A document transport unit that transports a document so that it passes over the surface of the light-transmitting member, The image reading unit is supported by a hinge mechanism that allows the document transport unit to be opened and closed, The aforementioned document transport unit is A first contact portion that contacts the image reading unit, It has a second contact portion which is positioned closer to the hinge mechanism than the first contact portion in the width direction perpendicular to the document transport direction and which contacts the image reading unit, The aforementioned hinge mechanism is, A first member fixed to the image reading unit, The first shaft is supported by the first member, A second member that rotates relative to the first member about the first axis, A second axis is positioned parallel to the first axis at a different location and supported by the second member, A third member that rotates relative to the second member about the second axis, A third axis is positioned parallel to the second axis at a different location and supported by the third member, The document transport unit is fixed, and a fourth member rotates relative to the third member about the third axis such that the first contact portion and the second contact portion contact the image reading unit, A first biasing unit having a first spring that applies torque in the direction of opening the document transport unit according to the rotation angle of the document transport unit relative to the image reading unit, The fourth member has a second biasing unit having a second spring that applies torque to the second contact portion so that it contacts the light-transmitting member, The fourth member has a first side plate that supports the third axis, The second spring is positioned outward from the first side plate of the fourth member in the axial direction of the third shaft. A document reading device characterized by the following features. [Configuration 2] The fourth member has a first top plate connected to the upper part of the first side plate, The third member has a second side plate that supports the third axis and a second top plate that is connected above the second side plate. The fourth member is arranged such that the first top plate is above the second top plate. The second spring is positioned below the second top plate and above the lower end of the first side plate when the document transport unit is closed relative to the image reading unit. The document reading device according to configuration 1, characterized by the above. [Configuration 3] The third member extends outward from the second side plate in the axial direction of the third shaft and has an upper end pressure receiving portion that engages with the upper end of the second spring and receives the biasing force of the second spring. The fourth member extends outward from the first side plate in the axial direction of the third shaft and has a lower end pressure receiving portion that engages with the lower end of the second spring and receives the biasing force of the second spring. The document reading device according to configuration 2, characterized in that it is a document reading device. [Structure 4] The first member has a one-sided pressure receiving portion that receives the biasing force of the first spring toward one side, The third member has a pressure-receiving portion on the other side that receives the biasing force of the first spring toward the other side, The first biasing unit is, A first support member that contacts the one-side pressure receiving portion, supports the one-side end of the first spring, and is slidably supported by the second member, It has a second support member that contacts the other pressure receiving portion and supports the other end of the first spring, When the rotation angle of the second member is changed relative to the first member, the distance between the one-sided pressure receiving portion and the other-sided pressure receiving portion is changed, and the biasing force of the first spring is changed, thereby applying torque in the direction of opening the document transport unit in accordance with the rotation angle of the document transport unit relative to the image reading unit. A document reading device according to any one of configurations 1 to 3, characterized by the above. [Composition 5] The fourth member has a contact restricting portion that contacts the third member and restricts rotation when the document transport unit rotates around the third axis in a direction that closes it to the image reading unit, The aforementioned contact regulating section is, When closing the document transport unit relative to the image reading unit, it contacts the third member and transmits a force to rotate the third member. When the fourth member rotates relative to the third member such that the second contact portion contacts the light-transmitting member, it separates from the third member, allowing relative rotation between the third member and the fourth member. A document reading device according to any one of configurations 1 to 4, characterized by the above. [Composition 6] The third axis is positioned on the opposite side of the second axis from the first axis when viewed from the axial direction of the third axis. A document reading device according to any one of configurations 1 to 5, characterized by the above. [Composition 7] The fourth member has a third side plate that faces the first side plate and supports the third axis together with the first side plate, The second biasing portion is positioned outside the third side plate of the fourth member in the axial direction of the third shaft and has a third spring that applies torque so that the second contact portion contacts the light-transmitting member. A document reading device according to any one of configurations 1 to 6, characterized by the above. [Structure 8] A document reading device described in any one of configurations 1 to 7, The system includes an image forming unit that forms an image read by the aforementioned document reading device onto a sheet. An image forming apparatus characterized by the following features. [Explanation of symbols]

[0091] 3…Hinge mechanism / 10…Document scanning device / 20…ADF (Automatic Document Feeder) / 21a…Buttock part (first contact part) / 21b…Buttock part (second contact part) / 30…Reading unit / 31…Fixing member (first member) / 31A…Cam pin (one-sided pressure receiving part) / 32…Opening / closing member (second member) / 33…First rotating member (third member) / 33c…Top plate (second top plate) / 33d…Side plate (second side plate) / 33f…Spring support part (upper end support part) / 34…Second rotating member (fourth member) / 34c…Top plate (first top plate) / 34d(L)…Side plate (first side plate) / 34d(R)…Side plate (third side plate) / 34i…Spring support part (lower end support part) / 34k …Contact regulating part / 35…Hinge rotation axis (first axis) / 36…Book rotation axis (second axis) / 37…Lift axis (pressure receiving part on the other end) / 38…Equalize axis (third axis) / 39(L)…Spring (second spring) / 39(R)…Spring (third spring) / 40…Image reading unit / 51…First slider (first support member) / 52…Second slider (second support member) / 53…Spring (first spring) / 60…Image forming engine (image forming unit) / 100…Printer (image forming device) / 201…Platen glass (light-transmitting member) / An1…Opening / closing angle (rotation angle) / F1…First biasing unit / F2…Second biasing unit / T…Torque

Claims

1. A hinge mechanism that supports an image reading unit so that a document transport unit can be opened and closed, A first member fixed to the image reading unit, The first shaft is supported by the first member, A second member that rotates relative to the first member about the first axis, A second axis is positioned parallel to the first axis at a different location and supported by the second member, A third member having a pair of first side plates and a first top plate connected above the pair of first side plates, and rotating relative to the second member about the second axis, A third axis is positioned parallel to the second axis at a different location and supported by the third member, It has a pair of second side plates and a second top plate connected above the pair of second side plates, and the document transport unit is fixed to a fourth member that rotates relative to the third member about the third axis, The first biasing unit has a first spring that applies torque in the opening direction to the document transport unit relative to the image reading unit, The fourth member has a second biasing unit which has a second spring that applies torque to the fourth member so that the fourth member rotates relative to the third member about the third axis, The pair of second side plates are positioned outward from the pair of first side plates in the axial direction of the third axis, and the second top plate is positioned above the first top plate. The second spring is positioned outward from the pair of second side plates of the fourth member in the axial direction of the third shaft. A hinge mechanism characterized by the following:

2. The second spring is positioned below the second top plate and above the lower ends of the pair of second side plates when the document transport unit is closed relative to the image reading unit. The hinge mechanism according to feature 1.

3. The third member extends outward from the first side plate in the axial direction of the third shaft and has an upper end pressure receiving portion that engages with the upper end of the second spring and receives the biasing force of the second spring. The fourth member extends outward from the second side plate in the axial direction of the third shaft and has a lower end pressure receiving portion that engages with the lower end of the second spring and receives the biasing force of the second spring. The hinge mechanism according to feature 1.

4. The first member has a one-sided pressure receiving portion that receives the biasing force of the first spring toward one side, The third member has a pressure-receiving portion on the other side that receives the biasing force of the first spring toward the other side, The first biasing unit is, A first support member that contacts the one-side pressure receiving portion, supports the one-side end of the first spring, and is slidably supported by the second member, It has a second support member that abuts against the other pressure receiving portion and supports the other end of the first spring, When the rotation angle of the second member is changed relative to the first member, the distance between the one-sided pressure receiving portion and the other-sided pressure receiving portion is changed, and the biasing force of the first spring is changed, thereby applying torque in the direction of opening the document transport unit in accordance with the rotation angle of the document transport unit relative to the image reading unit. The hinge mechanism according to feature 1.

5. The fourth member has a contact restricting portion that contacts the third member and restricts rotation when the document transport unit rotates around the third axis in a direction that closes it to the image reading unit, The aforementioned contact regulating section is, When closing the document transport unit relative to the image reading unit, it contacts the third member and transmits a force to rotate the third member. When the fourth member rotates relative to the third member, it separates from the third member, allowing relative rotation between the third member and the fourth member. The hinge mechanism according to feature 1.

6. The third axis is positioned on the opposite side of the second axis from the first axis when viewed from the axial direction of the third axis. The hinge mechanism according to feature 1.

7. The second biasing portion is positioned on the outer side of the pair of first side plates in the axial direction of the third shaft, opposite to the second spring, and has a third spring that applies torque to the fourth member so that the fourth member rotates relative to the third shaft. The hinge mechanism according to feature 1.

8. An image reading device comprising a hinge mechanism according to any one of claims 1 to 7, the document transport unit, and the image reading unit, The aforementioned image reading unit is A light-transmitting member, It has a reading unit that reads the image of the document through the light-transmitting member, The aforementioned document transport unit is A first contact portion that contacts the image reading unit, In the width direction perpendicular to the document transport direction, closer to the hinge mechanism than the first contact portion. It has a second contact portion positioned at a certain location and in contact with the image reading unit, The fourth member rotates relative to the third member about the third axis such that the first contact portion and the second contact portion contact the image reading unit. An image reading device characterized by the following:

9. The image reading device according to claim 8, The system includes an image forming unit that forms an image read by the image reading device onto a sheet. An image forming apparatus characterized by the following features.

Images