Image forming apparatus

An image forming apparatus includes an opening closing unit openably arranged between first and second positions and an associating mechanism connecting a body unit with the opening closing unit and operating in association with the opening closing unit. The associating mechanism includes plural compression springs and a buffer member, urges the opening closing unit with a first compression spring among the plural compression springs when the opening closing unit is placed at the first position, urges the opening closing unit with the first compression spring and a second compression spring when the opening closing unit is placed at a third portion between the first portion and the second position, and buffers the motion of the opening closing unit with the buffer member when the opening closing unit is placed at a fourth position between the second position and the third position.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority benefits under 35 USC, section 119 on the basis of Japanese Patent Application No. 2015-090754, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to an image forming apparatus.

DESCRIPTION OF RELATED ART

With conventional image forming apparatuses such as printers, photocopiers, facsimile machines, and MFPs, for example an MFP has a scanner unit serving as an opening closing unit, which is arranged swingably via a hinge to the printer section as the body unit, or namely, supported in an openable manner (for example, see Japanese Patent Application Publication No. 2007-79212 (A1)).

Such a conventional MFP may be suffered from reduced controllability at a time that the scanner unit is open and closed, as the scanner is made in a larger size

BRIEF SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an image forming apparatus with improved controllability at a time that an opening closing unit is open and closed, in solving the problems of the conventional MFPs.

An image forming apparatus according to one aspect of the invention, includes an opening closing unit arranged in an openable manner between a first position and a second position with respect to a body unit; and an associating mechanism connecting the body unit with the opening closing unit and operating in association with opening and closing of the opening closing unit, wherein the associating mechanism includes plural compression springs and a buffer member, urges the opening closing unit with a first compression spring among the plural compression springs when the opening closing unit is placed at the first position, urges the opening closing unit with the first compression spring and a second compression spring when the opening closing unit is placed at a third portion between the first portion and the second position, and buffers the motion of the opening closing unit with the buffer member when the opening closing unit is placed at a fourth position between the second position and the third position.

These and other objects, features, aspects and advantages of the disclosed disc brake caliper will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, referring to the drawings, an image forming apparatus according to an embodiment of the invention are described in detail. In this description, an MFP is exemplified as the image forming apparatus of the invention.

FIG. 2is a perspective view showing an MFP according to the embodiment of the invention;FIG. 3is a schematic view showing the MFP according to the embodiment of the invention.

InFIG. 2andFIG. 3, an MFP11has a printer section12serving as a body unit of the MFP11, and a scanner unit13is provided in a swingable manner with respect to the printer section12via a hinge hg1as a first support mechanism, or namely, provided as an opening closing unit arranged in an openable manner.

The printer section12has a housing Cs, which includes a lower casing Lc, an upper cover Uc arranged swingably via a hinge hg2as a second support mechanism with respect to the lower casing Lc or namely arranged in an openable manner, and a side plate Ps arranged adjacently to the lower casing Lc on the double sides of the lower casing Lc as projecting upwardly from the lower casing Lc structuring side walls of the housing Cs.

The printer section12has, in the body of the printer section12, or namely at a lower portion of the apparatus body, a paper feeding device Ku including a paper cassette15serving as a medium container for containing the paper P as the media, and a feeding roller16for feeding the paper P in the paper cassette15to the medium conveyance route Rt1. The paper cassette15is disposed in a way that a front end surface Sa faces a front panel Wf of the lower casing Lc, and a handle101is formed at the front end surface Sa so that an operator can pull the paper cassette15forward by his hand.

The medium conveyance route Rt1is extended with curves, and along the conveyance direction of the paper P, disposed are a first conveyance roller pair17for conveying the fed paper P on a downstream side of the feeding roller16, an image forming section Gu for forming toner images as multicolor developed images on a downstream side of the first conveyance roller pair17, a fixing device19serving as a fixing unit forming multicolor images upon fixing multicolor toner images to the paper P on a downstream side of the image forming section Gu, a second roller pair18conveying the paper P formed with multicolor images on a downstream side of the fixing device19, and a paper delivery unit20serving as a medium delivery unit for delivering the paper P to an exterior of the apparatus body on a downstream side of the second conveyance roller pair18.

The image forming section Gu includes such as, e.g., image forming units25of respective colors, yellow, magenta, cyan, and black disposed along the medium conveyance route Rt1, photosensitive drums26serving as image carriers provided respectively in the image forming units25, LED heads, not shown, disposed facing the photosensitive drums26, serving as exposure devices forming electrostatic latent images as latent images by exposing the photosensitive drums26, developing devices, not shown, disposed respectively in the image forming units25, serving as developing devices forming toner images from developing the electrostatic latent images, and transfer rollers27disposed facing the photosensitive drums26at a lower side of the respective image forming units25, transferring the toner images formed on the photosensitive drums26to the paper P in a sequentially overlapping manner, serving as a transfer member for forming multicolor toner images. Toner cartridges25aare provided for containing toner as developer.

The fixing device19includes a heating roller28serving as a first fixing member heating and melting the toner images on the paper P, and a pressure roller29serving as a second fixing member pressing the melting toner images to the paper P.

The paper delivery unit20has a delivery roller pair21, and the paper P conveyed along the medium conveyance route Rt1is delivered by the delivery roller pair21to a stacker24as a medium stacking section out of a delivery outlet24formed at the upper cover Uc.

The scanner unit13includes a flatbed portion31as an image reading section, and an automatic document feeder32as a document feeder disposed above the flatbed portion31in an operable manner with respect to the flatbed portion31. The flatbed portion31includes, e.g., an image sensor unit not shown as a reading unit, and an original document table33as a first original document placing table for placing original documents. The automatic document feeder32includes, e.g., an original document table34serving as a second original document placing table for placing original documents, and a pickup roller not shown feeding out the original document from the original document table34.

The flatbed portion31is formed with a control panel35as projecting forward, and the control panel35includes a display portion38for notifying the operator of a variety of information, and a controller39for rendering the operator control.

Operation of the MFP11where the MFP11is used as a photocopier to read images on an original document with the scanner unit13and then to print the read images on the paper P at the printer section12, is described next.

The operator sets the original document on the original document table33of the scanner unit13, and manipulates the controller39of the control panel35to enter various settings such as, e.g., selection of copy number and size of the paper P, magnification of zooming in and out. When a start key is pushed, the image sensor unit is moved to read the images on the original document, and the image data are transmitted to the printer section12.

At the printer section12, the image data sent from the scanner unit13are processed at a printer controller, not shown; signals of respective colors are sent to the LED heads; electrostatic latent images are formed upon exposure of the photosensitive drums26of the respective image forming units25; the developing devices develop toner images from the electrostatic latent images.

To the contrary, the paper P fed into the medium conveyance route Rt1out of the paper cassette15is conveyed with the first conveyance roller pair17and sent to the image forming section Gu; the toner images of the respective colors are transferred onto the paper P at the image forming section Gu to form the multicolor toner images. The paper P is then sent to the fixing device19to fix the multicolor toner images to the paper P at the fixing device19, thereby forming multicolor images.

The paper P formed with the multicolor images are conveyed by the second conveyance roller pair18and delivered to the stacker22out of the delivery outlet24by the delivery roller pair21.

In a case where paper jams occur in the printer section12or where the toner cartridge25ais replaced since the toner cartridge25ahas no toner, the operator moves pivotally the scanner unit13around the hinge hg1as a center to open the unit13, and moves pivotally the upper cover Uc around the hinge hg2as a center to open the cover Uc. After removing the jammed paper P or replacing the toner cartridge25a, the upper cover Uc is closed, and then, the scanner unit13is closed.

The upper cover Uc, however, is no more than covering the lower casing Lc, and because of a light weight, the upper cover Uc may not provide any impact to the MFP11when opening and closing. To the contrary, the scanner unit13has such as the flatbed portion31and the automatic document feeder32and is heavy, so that urging force may be produced when opening and closing the scanner unit13, thereby providing an impact on the MFP11at the end of opening and closing operation.

In this embodiment, to prevent the MFP11from receiving impacts according to opening and closing of the scanner unit13, a scanner support unit40is arranged as a support unit as well as an associating mechanism connecting between the printer section12and the scanner unit13. The scanner support unit40is disposed as to connect the printer section12and the scanner unit13on the double sides of the MFP11, and operates in association with opening and closing operation of the scanner unit13.

FIG. 1is a vertical cross section showing a scanner support unit according to an embodiment of the invention;FIG. 4is a side view showing the MFP in a state that the scanner unit is open according to the embodiment of the invention;FIG. 5is an essential perspective view showing an essential portion of the MFP in the state that the scanner unit is open according to the embodiment of the invention;FIG. 6is a perspective view showing the scanner support unit when viewed from a bottom side according to the embodiment of the invention;FIG. 7is a lateral cross section showing the scanner support unit according to the embodiment of the invention.

InFIG. 4, the MFP11includes the printer section12, the scanner unit13, the housing Cs of the printer section12, the lower casing Lc, the upper cover Uc, the side plate Ps, the hinge hg1, the flatbed portion31, the automatic document feeder32, the original document table33, and the scanner support unit40. It is to be noted that, where an angle of the lower surface of the scanner unit13or the upper surface of the original document table33with respect to the horizontal surface is set to an open angle α of the scanner unit13,FIG. 4illustrates a state that the scanner unit13is open up to the maximum value αmax of the open angle α, or 56 (fifty six) degrees, in this embodiment.

The scanner support unit40is compressed as changing an inclined angle β with respect to the horizontal surface according to opening and closing of the scanner unit13, connects the printer section12with the scanner unit13, and supports the scanner unit13. An end of the scanner support unit40on a side near the printer section12is supported swingably around a prescribed portion of the side plate Ps, or namely around a support shaft sh1disposed on a further front side of the delivery outlet24, whereas an end of the scanner support unit40on a side near the scanner unit13is supported swingably around a prescribed portion of a lower surface of the scanner unit13, or namely around a support shaft sh2disposed adjacent to the hinge hg1with a prescribed distance away from the hinge hg1.

It is to be noted that the scanner support unit40is inclined as having the inclined angle β of a prescribed value with respect to the horizontal surface, or the angle of 16 (sixteen) degrees in this embodiment, in a state that the scanner unit13is closed, and at that time, the scanner support unit40is contained in a container81formed in the side plate Ps as opening the top surface.

The scanner support unit40includes an inner casing41as a first casing, and an outer casing42as a second casing enveloping the inner casing41disposed movable and slidable with respect to the inner casing41. The scanner support unit40is formed with holes H1, H2provided at one ends83,84of the inner casing41and the outer casing42; the support shafts sh1, sh2are penetrated through the holes H1, H2, respectively, in a pivotal manner, thereby making the scanner support unit40supported swingably with respect to the printer section12and the scanner unit13; the other end85of the inner casing41is compressed as in a state being inserted in the other end86of the outer casing86. Each of the inner casing41and the outer casing42has a cross section extending in the longitudinal direction in a traversely square letter-U shape.

According to opening of the scanner unit13, the inner casing41is pulled out from the outer casing42in a prescribed amount, and thereby the scanner support unit40is expanded. According to closing of the scanner unit13, the inner casing41is pushed into the outer casing42in a prescribed amount, and thereby the scanner support unit40is compressed.

The inner casing41includes a top wall e1, side walls f1, g1pending from opposite edges of the top wall e1, and projecting walls h1, i1projecting from the lower ends of the side walls f1, g1as facing each other. The outer casing42includes a top wall e2, side walls f2, g2pending from opposite edges of the top wall e2, and projecting walls h2, i2projecting from the lower ends of the side walls f2, g2as facing each other. The inner casing41is contained in a manner movable and slidable with respect to the outer casing42. In the inner casing41and the outer casing42, a plurality of springs, or namely in this embodiment, springs S1, S2as first and second urging members, and a damper Dp as a buffer member are arranged coaxially. In this embodiment, the springs S1, S2operate as first and second compression springs.

The damper Dp includes a cylinder portion67as a first buffer element, and a piston portion68as a second buffer element disposed movably relatively to the cylinder portion67, and the motion of the piston portion68is buffered from a fluid contained in the cylinder portion67for buffering, thereby making the motion of the scanner unit13buffered.

Engagement portions h1′, i1′ serving as first open angle limiting members are formed at the projecting walls h1, i1at the end85of the inner casing41, and engagement portions h2′, i2′ serving as second open angle limiting members are formed at the projecting walls h1, i1at the end86of the outer casing42. The engagement portions h1′, i1′ are formed from widening the widths of the projecting walls h1, i1, and the engagement portions h2′, i2′ are formed from widening the widths of the projecting walls h2, i2. The positions of the engagement portions h1′, h2′, i2′ are set so that the open angle α of the scanner unit14becomes the maximum value αmax when the engagement portions h1′, i1′ and the engagement portions h2′, i2′ are engaged with each other. Accordingly, if the inner casing41is pulled out of the outer casing42in the preset maximum amount, the engagement portions h1′, i1′ and the engagement portions h2′, i2′ come to engage each other, thereby preventing the inner casing41from pulled out of the outer casing42further.

The hole H1is formed at the side walls f1, g1provided at the end83of the inner casing41to render the support shaft sh1penetrate the end83, and the hole H2is formed at the side walls f2, g2provided at the end84of the outer casing42to render the support shaft sh2penetrate the end84. Where a distance between the holes H1, H2is denoted as Lh, the distance Lh takes the maximum valve Lhmax in a state that the scanner unit13is open and the minimum value Lhmin in a state that the scanner unit13is closed.

It is to be noted that the end83of the inner casing41is covered with an end wall j1pending from the top wall e1, and the end84of the outer casing42is covered with an end wall j2pending from the top wall e2.

Next, an arrangement state of the springs S1, S2and the damper Dp is described.

In this situation, the spring S1is disposed inside the inner casing41and the outer casing42; the spring S2is disposed on a radially inner side of the spring S1; and the damper Dp is disposed on a radially inner side of the spring S2. Accordingly, where a distance between the top wall e1and the projecting walls h1, i1of the inner casing41is denoted by δ1, where a distance between the side walls f1, g1of the inner casing41is denoted by δ2, where a distance between the top wall e2and the projecting walls h2, i2of the outer casing42is denoted by δ3, where a distance between the side walls f2, g2of the outer casing42is denoted by δ4, where the outer diameter of the spring S1is denoted by D1, where the inner diameter of the spring S1is denoted by d1, where the outer diameter of the spring S2is denoted by D2, where the inner diameter of the spring S2is denoted by d2, and where the maximum diameter of the damper Dp is denoted by D3, the following formulae are satisfied.
D1<δ1=δ2<δ3=δ4
D2<d1
D3<d2

A contact member61as a first engagement member is disposed adjacently to the end wall j1in the inner casing41. The contact member61has a square pillar shape as to be contained in the inner casing41, and is formed with a first engagement surface m1for engaging and fixing the one ends of the springs S1, S2and the damper Dp to the end surface on a side of the end85.

A contact member62as a second engagement member is disposed adjacently to the end wall j2in the outer casing42. The contact member62includes a flange portion63as a first contact portion formed adjacently with the end wall j2, and a projecting portion64as a second contact portion formed projecting toward the side of the end86from the flange portion63. The flange portion63has a rectangular shape contained in the outer casing42, and the projecting portion64has a cylindrical shape contained in the spring S1. A second engagement surface m2is formed at an end surface of the flange portion63on the side of the end83for engaging and contacting the other end of the spring S1, and a third engagement surface m3is formed at an end surface of the projecting portion64on the side of the end83for engaging and contacting the other end of the spring S2and the damper Dp.

Where the scanner unit13is open and where the distance Lh between the holes H1, H2takes the maximum value Lhmax, the spring S1is engaged with the first and second engagement surfaces m1, m2, and enters into a compressed state between the first and second engagement surfaces m1, m2. It is to be noted that where the distance between holes H1, H2takes the maximum value Lhmax, the engagement portions h1′, i1′ and the engagement portions h2′, i2are engaged with each other, thereby keeping a state that the inner casing41is pulled out of the outer casing42in a prescribed amount. The spring S2and the damper Dp at that time engage only the first engagement surface m1and does not engage the third engagement surface m3.

That is, where the length of the spring S1at a time of no load, or namely a free length is denoted by LS1, where the free length of the spring S2is denoted by LS2, where the free length of the damper Dp is denoted by Ld, where the length between the first and second engagement surfaces m1, m2when the length Lh between the holes H1, H2takes the maximum value Lhmax, or namely the maximum length is denoted by Lm1, and where the maximum length between the first and third engagement surfaces m1, m3is denoted by Lm2, the following formulae are satisfied.
Lm1<LS1
Lm2<Lm1
LS2<Lm2
Ld<LS2

Next, respective states of the scanner support unit40when the scanner unit13is open and closed are described.

FIG. 8is a view showing a first state of the scanner support unit according to the embodiment of the invention;FIG. 9is a view showing a second state of the scanner support unit according to the embodiment of the invention;FIG. 10is a view showing a third state of the scanner support unit according to the embodiment of the invention; andFIG. 11is a view showing a fourth state of the scanner support unit according to the embodiment of the invention. It is to be noted that inFIGS. 8 to 11, a single dot chain line NL indicates a center line of the scanner support unit40when the inclined angle β takes the minimum value or namely 16 (sixteen) degrees.

InFIGS. 8 to 11, the scanner support unit40includes the inner casing41, the outer casing42, the springs S1, S2, and the damper Dp.

FIG. 8shows a state of the scanner support unit40where the open angle α of the scanner unit13(see,FIG. 2) is set to the maximum value αmax or namely 56 (fifty six) degrees and the inclined angle β is set to 38 (thirty eight) degrees.

In this situation, the inner casing41is pulled out of the outer casing42in the maximum amount, and the engagement portions h1′, i1′ (see,FIG. 6) and the engagement portions h2′, i2′ are engaged with each other. The spring S1engages the first and second engagement surfaces m1, m2and enters in a compressed state between the first and second engagement surfaces m1, m2. The spring S2and the damper Dp at that time do not engage the third engagement surface m3.

Accordingly, the spring S1urges the outer casing42in a direction moving the outer casing42toward the scanner unit13with urging force FS1-1according to the compressed amount of the spring S1and urges the scanner unit13in a direction opening the scanner unit13.

FIG. 9shows a state of the scanner support unit40where the open angle α of the scanner unit13is set to 15 (fifteen) degrees and the inclined angle β is set to 28 (twenty eight) degrees.

In this situation, the inner casing41is pushed into the outer casing42in a prescribed amount. The spring S1engages the first and second engagement surfaces m1, m2and enters in a compressed state between the first and second engagement surfaces m1, m2. The spring S2engages the first and third engagement surfaces m1, m3and enters in a compressed state between the first and third engagement surfaces m1, m3. The damper Dp at that time does not engage the third engagement surface m3.

Accordingly, the spring S1with urging force FS1-2according to the compressed amount, and the spring S2with urging force FS2-2according to the compressed amount, urge the outer casing42in a direction moving the outer casing42toward the scanner unit13and urge the scanner unit13in a direction opening the scanner unit13. It is to be noted that the urging force FS1-1and the urging force FS1-2satisfy the following formula.
FS1-1<FS1-2

FIG. 10shows a state of the scanner support unit40where the open angle α of the scanner unit13is set to 5 (five) degrees and the inclined angle β is set to 20 (twenty) degrees.

The inner casing41at that time is further pushed into the outer casing42. The spring S1engages the first and second engagement surfaces m1, m2and enters in a compressed state between the first and second engagement surfaces m1, m2. The spring S2engages the first and third engagement surfaces m1, m3and enters in a compressed state between the first and third engagement surfaces m1, m3. The damper Dp engages the first and third engagement surfaces m1, m3.

Accordingly, the spring S1with urging force FS1-3according to the compressed amount, and the spring S2with urging force FS2-3according to the compressed amount, urge the outer casing42in a direction moving the outer casing42toward the scanner unit13and urge the scanner unit13in a direction opening the scanner unit13. It is to be noted that the urging force FS1-2and the urging force FS1-3satisfy the following formula.
FS1-2<FS1-3
The urging force FS2-2and the urging force FS2-3satisfy the following formula.
FS2-2<FS2-3

The damper Dp with urging force FDp-3until that the fluid for buffering in the cylinder portion67reaches a steady state, urges the outer casing42in a direction moving the outer casing42toward the scanner unit13and urges the scanner unit13in a direction opening the scanner unit13.

FIG. 11shows a state of the scanner support unit40where the open angle α of the scanner unit13is set to 0 (zero) degree and the inclined angle β is set to 16 (sixteen) degrees, or namely where the scanner unit13is closed.

In this situation, the inner casing41is further pushed into the outer casing42. The spring S1engages the first and second engagement surfaces m1, m2and enters in a compressed state between the first and second engagement surfaces m1, m2. The spring S2engages the first and third engagement surfaces m1, m3and enters in a compressed state between the first and third engagement surfaces m1, m3. The damper Dp engages the first and third engagement surfaces m1, m3.

Accordingly, the spring S1with urging force FS1-4according to the compressed amount, and the spring S2with urging force FS2-4according to the compressed amount, urge the outer casing42in a direction moving the outer casing42toward the scanner unit13and urge the scanner unit13in a direction opening the scanner unit13. It is to be noted that the urging force FS1-3and the urging force FS1-4satisfy the following formula.
FS1-3<FS1-4
The urging force FS2-3and the urging force FS2-4satisfy the following formula.
FS2-3<FS2-4

The damper Dp with urging force FDp-4until that the fluid for buffering in the cylinder portion67reaches a steady state, urges the outer casing42in a direction moving the outer casing42toward the scanner unit13and urges the scanner unit13in a direction opening the scanner unit13.

The position of the scanner unit13when the open angle α is set to 56 (fifty six) degrees is set to the first position as the opening position; the position of the scanner unit13when the open angle α is set to 0 (zero) degree is set to the second position as the closing position; the position of the scanner unit13when the open angle α is set to 15 (fifteen) degrees is set to the third position; the position of the scanner unit13when the open angle α is set to 5 (five) degrees is set to the fourth position. Accordingly, the scanner unit13is disposed in an openable manner between the first and second positions; the scanner unit13moves from the first position via the fourth and third positions to the second position and is closed; and the scanner unit13moves from the second position via the fourth and third positions to the first position and is open.

The spring S1is placed in a state normally compressed between the first and second positions to urge the scanner unit13; where the scanner unit13is placed at the third position, the springs S1, S2urge the scanner unit13; where the scanner unit13is placed at the fourth position, the springs S1, S2urge the scanner unit13, and the damper Dp, or the buffer member, buffers the motion of the scanner unit13; where the scanner unit13is placed at the second position, the springs S1, S2urge the scanner unit13.

Next, the operation of the scanner support unit40when the scanner unit13is open and closed is described.

As shown inFIG. 11, where the scanner unit13is closed and placed at the second position, the inclined angle β (see,FIG. 1) of the scanner support unit40is set to 16 (sixteen) degrees as the initial angle, and the open angle α of the scanner unit13is set to 0 (zero) degree, so that the springs S1, S2urge the scanner unit13in a direction opening the scanner unit13with the urging forces FS1-4, FS2-4. The spring constants of the springs S1, S2are set so that, when a moment generated in a direction opening the scanner unit13with the urging forces FS1-4, FS2-4is compared with a moment generated in a direction closing the scanner unit13by the self-weight, the moment generated in the direction opening the scanner unit13is slightly smaller than the moment generated in the direction closing the scanner unit13by the self-weight. Accordingly the scanner unit13maintains the closed state as far as not receiving any external force.

With the printer section12(see,FIG. 2), in a case that a paper jamming occurs or that the toner cartridge25a(see,FIG. 3) is replaced, if the operator grips the scanner unit13to exert his force in the opening direction, the moment generated in the direction opening the scanner unit13becomes larger than the moment generated in the direction closing the scanner unit13by the self-weight, so that the scanner unit13can be opened with slight force.

Subsequently, as shown inFIG. 10, where the scanner unit13is open and placed at the fourth position, the inclined angle β of the scanner support unit40becomes larger, and the open angle α of the scanner unit13is set to 5 (five) degrees, thereby making smaller the moment generated in the direction closing the scanner unit13by the self-weight. As shown inFIG. 9, if the scanner unit13is further open and placed at the third portion, the engagement between the spring S2and the third engagement surface m3is released, and only the spring S1urges the scanner unit13in the direction opening the scanner unit13with the urging force FS1-4. With this operation, the moment generated in the direction opening the scanner unit13is made smaller.

As shown inFIG. 8, where the scanner unit13is further open and placed at the first position, the open angle α of the scanner unit13is set to 56 (fifty six) degrees, and the engagement portions h1′, i1′ and the engagement portions h2′, i2′ are engaged with each other, so that the scanner unit13is stopped in that state. The spring constant of the spring S1is set so that, when the moment generated in the direction opening the scanner unit13with the urging force FS1-4is compared with the moment generated in the direction closing the scanner unit13by the self-weight, the moment generated in the direction opening the scanner unit13is slightly larger than the moment generated in the direction closing the scanner unit13by the self-weight. Accordingly, the scanner unit13maintains the open state as far as not receiving any external force.

In this situation, when the scanner unit13is open, the scanner unit13may not be open vigorously, because the urging force urging the scanner unit13in the opening direction is made smaller, as the open angle α of the scanner unit13is made larger.

Subsequently, in a state shown inFIG. 8, if the operator grips the scanner unit13to exert his force in the closing direction, the moment generated in the direction opening the scanner unit13becomes smaller than the moment generated in the direction closing the scanner unit13by the self-weight, so that the scanner unit13can be closed with slight force.

As the inclined angle β of the scanner support unit40is made smaller and as the open angle α of the scanner unit13is made smaller, the moment generated in the direction closing the scanner unit13by the self-weight is made larger, and the spring S2is engaged with the third engagement surface m3as shown inFIG. 9, so that the springs S1, S2urge the scanner unit13in the direction opening the scanner unit13with the urging force FS1-4. With this operation, the moment generated in the direction opening the scanner unit13is made larger.

Where the inclined angle β of the scanner support unit40is further made smaller, and as shown inFIG. 10, where the open angle α of the scanner unit13becomes 5 (five) degrees, the damper Dp engages the third engagement surface m3, thereby buffering the motion of the scanner unit13.

In this situation, when the scanner unit13is closed, as the open angle α is made smaller, not only the urging force urging in the direction opening the scanner unit13is made larger, but also the motion of the scanner unit13is buffered by the damper Dp, so that the scanner unit13may not be closed vigorously.

According to the embodiment thus described, as the scanner support unit40includes the springs S1, S2and the damper Dp, the spring S1urges the scanner unit13when the scanner unit13is placed at the first portion, and the springs S1, S2urge the scanner unit13with the urging forces FS1-2, FS2-2when the scanner unit13is placed at the third position, so that the scanner unit13may not be open and closed vigorously. The damper Dp buffers the motion of the scanner unit13when the scanner unit13is placed at the fourth position, thereby surely preventing the scanner unit13from closing vigorously.

The MFP11, therefore, does not receive any impact at the end of the opening and closing operation of the scanner unit13, so that controllability at a time opening and closing the scanner unit13can be improved even where the scanner unit13is made in a larger size.

Because the scanner support unit40is formed inside with no more than the springs S1, S2and the damper Dp, not only the support unit structure for supporting the scanner unit13can be simplified, but also the MFP11itself can be made in a smaller size.

In the embodiment, because the springs S1, S2are made in a double structure, the scanner unit13can be supported adequately, thereby making smaller the load exerted to the hinge gh1(see,FIG. 2). Therefore, the durability of the MFP11can be improved.

Although in this embodiment the scanner support unit40is disposed at each side of the MFP11, the unit40can be provided at either one side.

Although in this embodiment the first and second springs S1, S2as the urging members are disposed, urging members in a plural number, e.g., three or more, may be arranged.

In this embodiment, the MFP11is described, but this invention is applicable to such as, e.g., printers, photocopiers, and facsimile machines.