JP2015199602A - image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus with which when an image is formed on narrow-width sheets, the sheets can be separated correctly on a one-by-one basis to reliably pick up one sheet at a time and therefore sheets can be prevented from being fed in an overlapped state.SOLUTION: The image forming apparatus is configured such that a lift mechanism 90 raises upward a support lever 102 to raise upward a pressure plate 51 located above the support lever 102, and when narrow-width sheets 3 are set in a sheet cassette 11 and the sheet cassette 11 is received in a cassette reception part 50 of a laser beam printer 1, a lift release mechanism 91 moves the support lever 102 from the raised position to a horizontal position to lower the pressure plate.

Description

  The present invention relates to an image forming apparatus including a sheet cassette that can be guided according to the width size of a sheet stored in the sheet cassette.

  2. Description of the Related Art Conventionally, various sheet cassettes that can be guided according to the width size of a sheet that is used and accommodated in an image forming apparatus have been proposed.

  For example, in Japanese Patent Application Laid-Open No. 61-2443736, each of the two sheet width regulating plates is formed with a jump table operating piece having a cam surface protruding on the lower surface of the sheet placing table, and is rotated on the sheet placing table. In the jump table provided so as to be movable, a paper supply device is described in which a sliding slope is formed in sliding contact with the cam surface.

  In such a paper supply device, when a paper having a narrow paper width, such as a postcard, is used, the paper width regulating plate is moved to the center of the paper placement table. At this time, in response to the movement of the paper restricting plate, the cam surface of the jumping base operating piece provided on the paper width restricting plate is brought into sliding contact with the jumping base sliding slope, whereby the jumping base is placed on the paper placement table. Appears upward from the surface.

  This prevents the tip of small and stiff paper such as postcards from drooping, and allows the paper to be fed in the direction of the paper feed roller. Thus, it is possible to perform paper feeding without being performed.

Japanese Patent Laid-Open No. 61-243736

  In the paper feeding device disclosed in Patent Document 1, when a small size paper such as a postcard is used, when the paper width restricting plate is moved toward the center of the paper placing table, the jumping base is moved in conjunction with this. It protrudes upward from the paper placement surface of the table. As a result, the number of small-size sheets that can be placed on the sheet placement table is limited in accordance with the amount of upward movement of the jump table.

  However, in general, the user wants to print on as many sheets as possible, and in order to reduce the number of sheets set on the sheet mounting table, the user often forcibly sets the sheets on the sheet mounting table exceeding the limit number.

  As described above, when the number of sheets exceeds the limit on the sheet table, the sheets are strongly pressed against each other, so that the friction between the sheets becomes too large. As a result, there is a problem that the paper cannot be normally taken into the printing apparatus.

  Further, it is difficult to separate the sheets one by one, and there is a problem that the pickup of the sheets fails due to being taken into the printing apparatus in a state where a plurality of sheets are overlapped.

  The present invention solves the problems of the prior art, and when forming an image on a sheet having a small width size, the sheet can be properly separated one by one and the sheet can be reliably picked up. An object of the present invention is to provide an image forming apparatus capable of preventing the sheets from being fed in a state where they are overlapped.

  In order to achieve the above object, an image forming apparatus according to an embodiment of the present invention includes a sheet cassette that stores a plurality of sheets, a cassette storage that stores the sheet cassette, and a sheet cassette that is stored in the cassette storage. An image forming apparatus including an image forming unit that forms an image on a fed sheet, a pressure plate disposed at a bottom of the sheet cassette, on which a plurality of sheets are stacked, and a sheet provided on the sheet cassette. A side guide that guides the width direction of the sheet and is movable in accordance with the width size of the sheet, and a sheet upper limit regulation that is provided at a position facing the pressure plate by the side guide and regulates an upper limit of sheets stacked on the pressure plate And when the side guide is moved to a position narrower than a predetermined sheet width, the pressure is interlocked with the movement of the side guide. A lift mechanism for lifting and provided in the cassette accommodating portion, and wherein said further comprising a lift releasing mechanism for releasing the lift function of the lift mechanism when accommodating the sheet cassette in the cassette accommodating portion.

  In order to achieve the above object, an image forming apparatus according to an embodiment of the present invention includes a sheet cassette that stores a plurality of sheets, a cassette storage that stores the sheet cassette, and a sheet cassette that is stored in the cassette storage. An image forming apparatus including an image forming unit that forms an image on a fed sheet, a pressure plate disposed at a bottom portion of the sheet cassette, on which a plurality of sheets are stacked, and a lift for lifting and holding the pressure plate And a lift release mechanism which is provided in the cassette housing portion and operates the lift mechanism to lower the pressure plate when the sheet cassette is housed in the cassette housing portion.

  In the image forming apparatus according to an embodiment of the present invention, in the sheet cassette accommodated in the cassette accommodating portion, the sheet cassette is loaded on the pressure plate on the side guide that guides the width direction of the sheet and is movable in accordance with the sheet width size. A seat upper limit restricting portion for restricting the upper limit of the sheet to be provided, and when the side guide is moved to a width position narrower than a predetermined sheet width, the lift mechanism and the cassette housing that lifts the pressure plate in conjunction with the movement of the side guide A lift releasing mechanism is provided for releasing the lift function of the lift mechanism when the sheet cassette is accommodated in the cassette accommodating portion.

  Here, when a sheet narrower than a predetermined sheet width is set in the sheet cassette, the side guide is moved in accordance with the sheet width size. At this time, since the pressure plate is lifted via the lift mechanism, the number of sheets that can be stacked on the pressure plate is restricted by the distance between the sheet upper limit restricting portion of the side guide and the pressure plate. As a result, excessive sheets are not forcibly set in the sheet cassette.

  After the sheets are set in the sheet cassette, when the sheet cassette is accommodated in the cassette accommodating portion of the image forming apparatus, the lifting function of the pressure plate by the lift mechanism is canceled by the lift releasing mechanism provided in the cassette accommodating portion, and the pressure plate Is lowered. When the pressure plate is lowered as described above, the plurality of sheets set in the sheet cassette are not pressed against each other, and the friction generated between the sheets is remarkably reduced.

  Accordingly, the sheet can be normally taken into the printing apparatus reliably, and the sheets are separated one by one and prevented from being taken into the image forming apparatus in a state where a plurality of sheets are overlapped. Can be reliably picked up.

  An image forming apparatus according to an embodiment of the present invention is provided at a bottom portion of a sheet cassette, lifts and holds a pressure plate on which a plurality of sheets are stacked, and provided in a cassette housing portion. A lift release mechanism that operates the lift mechanism to lower the pressure plate when housed in the unit. When a sheet is set in the sheet cassette, since the pressure plate is lifted by the lift mechanism, the number of sheets that can be set in the sheet cassette is regulated according to the lift position of the pressure plate. As a result, excessive sheets are not forcibly set in the sheet cassette.

  After the sheets are set in the sheet cassette, when the sheet cassette is accommodated in the cassette accommodating portion of the image forming apparatus, the lift mechanism is operated by the lift releasing mechanism provided in the cassette accommodating portion, and the pressure plate is lowered. When the pressure plate is lowered as described above, the plurality of sheets set in the sheet cassette are not pressed against each other, and the friction generated between the sheets is remarkably reduced.

  Accordingly, the sheet can be normally taken into the printing apparatus reliably, and the sheets are separated one by one and prevented from being taken into the image forming apparatus in a state where a plurality of sheets are overlapped. Can be reliably picked up.

It is a principal part side sectional view of the laser printer concerning a 1st embodiment of the present invention. It is a perspective view which shows the state which set the side guide to the sheet | seat of a standard size in the sheet cassette used for the laser printer which concerns on 1st Embodiment of this invention. FIG. 3 is a perspective view of the sheet cassette shown without the pressure plate in the perspective view shown in FIG. 2 according to the first embodiment of the present invention. It is explanatory drawing which expands and shows the principal part of a side guide adjustment mechanism in the state which set the side guide which concerns on 1st Embodiment of this invention to the sheet | seat of standard size. It is a perspective view which shows the state which set the side guide to the postcard size sheet | seat except the pressure plate in the sheet cassette used for the laser printer which concerns on 1st Embodiment of this invention. In the perspective view shown in FIG. 5, it is a perspective view of the sheet cassette shown except a control lever. It is explanatory drawing which expands and shows the principal part of a side guide adjustment mechanism in the state which set the side guide which concerns on 1st Embodiment of this invention to the postcard size sheet | seat. FIG. 2 is a schematic cross-sectional view showing a part of the main part of the sheet cassette before the sheet cassette according to the first embodiment of the present invention is set in the cassette housing part of the laser printer. FIG. 3 is a schematic cross-sectional view showing a part of the main part of the sheet cassette in a state where the sheet cassette according to the first embodiment of the present invention is being set in the cassette housing part of the laser printer. FIG. 3 is a schematic cross-sectional view showing a part of the main part of the sheet cassette just before the setting of the sheet cassette to the cassette housing part of the laser printer according to the first embodiment of the present invention is completed. FIG. 3 is a schematic cross-sectional view showing a part of the main part of the sheet cassette in a state where the setting of the sheet cassette to the cassette housing part of the laser printer according to the first embodiment of the present invention is completed. FIG. 5 is a side sectional view of a main part of the laser printer in a state where a pressure plate is raised through a driving mechanism of the laser printer after the setting of the sheet cassette to the cassette housing portion of the laser printer is completed. It is a perspective view which shows the state which set the side guide to the sheet | seat of a standard size in the sheet cassette used for the laser printer which concerns on 2nd Embodiment. It is explanatory drawing which expands and shows the principal part of a side guide adjustment mechanism in the state which set the side guide to the sheet | seat of standard size. It is explanatory drawing which expands and shows a part of principal part of a side guide adjustment mechanism further in the state which set the side guide to the sheet | seat of standard size. It is a perspective view which shows the state which set the side guide to the postcard size sheet | seat except the pressure plate in the sheet cassette used for a laser printer. It is explanatory drawing which expands and shows a part of side guide adjustment mechanism in the state which set the left side guide to the postcard size sheet | seat. It is explanatory drawing which shows typically the change of the state of a control lever and a support lever, when moving a side guide from a standard size sheet | seat to a postcard size sheet | seat. It is explanatory drawing which shows typically the principal part of the lift mechanism before setting a sheet cassette in the cassette accommodating part of a laser printer. It is explanatory drawing which shows typically the principal part of a lift mechanism in the state which is setting the sheet cassette in the cassette accommodating part of a laser printer. It is explanatory drawing which shows typically the principal part of a lift mechanism in the state which the setting of the sheet cassette with respect to the cassette accommodating part of a laser printer was completed.

Hereinafter, the present invention will be described based on an embodiment in which a laser printer is embodied with reference to the drawings.
(First embodiment)
<Overall configuration of laser printer>
As shown in FIG. 1, a laser printer 1 as an example of an image forming apparatus forms an image on a feeder unit 4 for feeding a sheet 3 (see FIG. 8 and the like) into a main body casing 2 and the sheet 3. The image forming unit 5 is provided.

A front cover 2a that can be opened and closed is provided on the front side of the main casing 2 (in the following description, the right in FIG. 1 is the front and the left is the rear), and is open from the opening that is formed when the front cover 2a is opened. A process cartridge 30 described later is detachable.
<Configuration of feeder section>
The feeder unit 4 is detachably mounted on a cassette housing unit 50 provided at the bottom of the main body casing 2 and is installed below the sheet 3 at the lower part of the sheet cassette 11 so as to feed paper. In order to lift the seat 3, there are provided a pressure plate 51 that is swingably provided so that the front is lifted, and a lift plate 52 that is installed below the pressure plate 51 and lifts the pressure plate 51 from below. The lift plate 52 is supported by the sheet cassette 11 at the rear end 53 so as to be rotatable. As will be described later, the lift plate 52 is rotated around the rear end 53 by being given a rotational driving force by a driving force from the apparatus main body. Thus, the pressure plate 51 is lifted.

  In addition, a pickup roller 61 that is in contact with the topmost sheet 3 stacked on the sheet cassette 11 from above is disposed above and in front of the sheet cassette 11, and a separation roller 62 is disposed in front of the pickup roller 61. . The separation roller 62 is disposed to face the separation pad 12 attached to the sheet cassette 11. In front of the separation roller 62, a paper dust removing roller 13 and a counter roller 14 are arranged to face each other. After the sheet 3 passes between the two rollers, the direction of the sheet 3 is changed backward along the conveyance path 19.

  Further, a registration roller 15 is disposed above the pickup roller 61.

In the feeder unit 4 configured as described above, the sheet 3 in the sheet cassette 11 is lifted by the lift plate 52 and the pressure plate 51, and the uppermost sheet 3 is sent to the separation roller 62 side by the pickup roller 61. Due to the friction between the separation roller 62 and the separation pad 12, only the uppermost sheet 3 is sent to the opposing roller 14 side and conveyed to the image forming unit 5 one by one.
<Configuration of image forming unit>
The image forming unit 5 forms an image on a sheet sent from the feeder unit by a known electrophotographic method.

  The image forming unit 5 includes a scanner unit 20, a process cartridge 30, a fixing unit 40, and the like. Since the scanner unit 20, the process cartridge 30, the fixing unit 40, and the like constituting the electrophotographic system and the image forming unit 5 are well known, detailed description thereof is omitted here.

The sheet on which the image is formed by the image forming unit 5 is conveyed to the paper discharge path 44 and is discharged onto the paper discharge tray 46 by the paper discharge roller 45.
<Configuration of sheet cassette>
Next, the configuration of the sheet cassette 11 will be described with reference to FIGS. A pressure plate 51 is rotatably supported on the bottom 70 of the sheet cassette 11 by two rotation support portions 71 (only the rotation support portion 71 on the left side in FIG. 2) is lifted up. A plurality of sheets 3 are stacked on the pressure plate 51 in a stacked state. As shown in FIG. 2, a guide hole 5 </ b> A is formed on the left side of the pressure plate 51, and a guide hole 51 </ b> B is formed on the right side of the pressure plate 51. The guide hole 51A guides the left side guide 72A when moving a left side guide 72A described later toward the center in the width direction of the pressure plate 51, and the guide hole 51B guides the right side guide 72B described later in the center in the width direction of the pressure plate 51. The right side guide 72B is guided when moving toward.

  On the left and right sides of the front side of the sheet cassette 11, a left side guide 72A and a right side guide 72B are disposed so as to be movable in the left-right direction. The side guides 72 </ b> A and 72 </ b> B guide the width direction of the sheet 3 and are configured to be movable with respect to the width size of the sheet 3.

  Further, at the front position on the upper edge of the left side guide 72A, the upper limit of the sheet 3 that extends in the horizontal direction facing the pressure plate 51 disposed on the bottom portion 70 of the sheet cassette 11 and is stacked on the pressure plate 51 is set. A sheet upper limit restricting portion 80A for restriction is provided. Similarly, a seat upper limit restricting portion 80B is provided at a front position on the upper edge of the right side guide 72B. The number of sheets 3 that can be stacked on the pressure plate 51 is restricted by a gap formed between the sheet upper limit restriction portions 80 </ b> A and 80 </ b> B and the pressure plate 51.

  Here, the moving mechanism of each side guide 72A, 72B is demonstrated based on FIG.3 and FIG.4. 3 and 4, the left side guide 72A is integrally formed of resin or the like, and extends from the rear side of the lower edge of the left side guide 72A toward the central portion in the width direction of the sheet cassette 11. Is formed horizontally, and a rack plate 75 on which rack teeth 74 are formed is provided on the distal end side (right end side) of the extending portion 73.

  A trapezoidal operating projection 81 is formed on the side edge of the rack plate 75 where the rack teeth 74 are formed. The operating protrusion 81 moves the side guides 72A and 72B toward each other toward the center in the width direction of the bottom portion 70 in accordance with the sheet 3 having a small width such as a postcard size (see FIGS. 5 to 7). An operation lever 82, which will be described later, is abutted and operated.

  Similarly to the left side guide 72A, the right side guide 72B is integrally formed of resin or the like, and extends from the front side of the lower edge of the right side guide 72B toward the center in the width direction of the sheet cassette 11. A protruding portion 76 is formed horizontally, and a rack plate 78 on which rack teeth 77 are formed is provided on the leading end side (left end side) of the extending portion 76.

  At the bottom portion 70 of the sheet cassette 11, the gear wheel 79 is rotatably supported at the center position in the width direction of the sheet 3 via the support portion 79 </ b> A while being separated from the side guides 72 </ b> A and 72 </ b> B by the same distance. Gear teeth (not shown) formed on the circumference of the gear wheel 79 are rack teeth 74 formed on the rack plate 75 of the left side guide 72A and racks formed on the rack plate 78 of the right side guide 72B. The teeth 77 mesh with each other.

  Further, an operating lever 82 is pivotally supported by a shaft 83 standing from the bottom 70 so as to be rotatable in the vicinity of the left side of the gear wheel 79. The actuating lever 82 has an upright portion 84 and a horizontal portion 85 formed integrally. A hook portion 86 is formed at the upper end of the standing portion 84, and the hook portion 86 guides the width direction of the standard size sheet 3 as shown in FIG. The engagement hole 101 is engaged. A protrusion 87 is formed on the horizontal portion 85 so as to face the rack teeth 74 of the rack plate 75 in the left side guide 72A. The protrusion 87 is in the width direction of the small sheet 3 such as a postcard size. When the side guides 72A and 72B are moved toward the central position in the width direction of the bottom portion 70, they are brought into contact with the operating projections 81 formed on the rack plate 75, whereby the operating lever 82 is In FIG. 4, it is rotated counterclockwise around the support shaft 83.

  The support shaft 83 is provided with a toggle spring 88 having one end locked to the upright portion 84 of the operating lever 82 and the other end locked to the bottom portion 70. The toggle spring 88 is actuated by the biasing force of the toggle spring 88. The lever 82 is always urged to rotate clockwise in FIG.

  As shown in FIG. 2 to FIG. 4, each sheet is guided to guide the width direction of a small sheet 3 such as a postcard size from the state in which the sheet width direction of a standard size sheet 3 (for example, A4 size sheet) is guided. When the side guides 72A and 72B are moved in the guide holes 51A and 51B toward the center position in the width direction of the sheet cassette 11, respectively, the rack plate 75 on the left side guide 72A side and the rack plate 78 of the right side guide 72B are While the gear wheels 79 are rotated by the rack teeth 74 and 77 in synchronization with each other, they are moved rightward and leftward, respectively. Then, immediately before the width between the side guides 72A and 72B becomes the width of the small sheet 3 such as a postcard, the hypotenuse 81A of the trapezoidal operation protrusion 81 formed on the rack teeth 74 is connected to the operation lever 82. It begins to abut against the protrusion 87. Then, when the width between the side guides 72A and 72B becomes the width of the sheet 3 having a small width such as a postcard, the protrusion 87 of the operation lever 82 is formed by the operation protrusion 81 as shown in FIG. Get over from the hypotenuse 81A to the upper side 81B. At this time, the operating lever 82 is rotated around the support shaft 83 in the clockwise direction against the urging force of the toggle spring 88. As a result, the hook portion 86 formed at the upper right end of the standing portion 84 is 100 engagement holes 101 are disengaged.

  A sheet rear end guide 89 for guiding the rear end of the sheet 3 is disposed at the rear end portion of the sheet cassette 11 so as to be slidable in the front-rear direction. When guiding the rear end of the standard size sheet 3, the sheet rear end guide 89 is disposed at the rear end portion of the sheet cassette 11 as shown in FIGS. 2 and 3, and has a width such as a postcard. When the rear end of the small sheet 3 is guided, it is moved and arranged in the front direction of the sheet cassette 11 as shown in FIGS.

  Subsequently, when the side guides 72A and 72B are moved toward the center in the width direction of the sheet cassette 11 in order to guide both sides of the sheet 3 having a small width such as a postcard, the side guides 72A and 72B are moved. A lift mechanism for lifting the pressure plate 51 in conjunction with the above will be described with reference to FIGS. 3, 5, and 6.

  As shown in FIGS. 3 and 5, the lift mechanism 90 basically includes a restriction lever 100 and a support lever 102. One end (rear end in FIGS. 3 and 5) of the regulating lever 100 is rotatably supported by a turning support portion 103 provided on the bottom 70 of the sheet cassette 11, and the other end (see FIG. 3, the front end in FIG. 5 is linked to one end of the support lever 102 (rear end in FIG. 3 and FIG. 5) and a pin 104 (see FIG. 8 and the like) so as to be able to rotate. An engagement hole 101 is formed in the regulation lever 100, and the upright portion 84 of the operation lever 82 is guided in the engagement hole 101 in the state of guiding the width direction of the standard size sheet 3 as shown in FIG. The hook part 86 formed in the is engaged.

  The other end of the support lever 102 (the front end in FIGS. 3 and 5) extends in the front-rear direction along a slide groove (not shown) formed in the bottom 70 of the sheet cassette 11, as shown in FIGS. A slidable slide lever 105 is rotatably supported at the upper end. The slide lever 105 is inserted into the slide groove and passes through the bottom portion 70, and a slider 106 is attached to the lower end of the slide lever 105 below the bottom portion 70. As will be described later, the slider 106 engages with an engaging portion 107 provided below the cassette housing portion 50 when the sheet cassette 11 is housed in the cassette housing portion 50 of the laser printer 1.

  As shown in FIGS. 3 and 5, a tension spring 108 is hung between the regulation lever 100 and the support lever 102, so that the regulation lever 100 and the support lever 102 are attached to the tension spring 108. The power is always biased in the direction of mutual folding.

  In the lift mechanism 90 configured as described above, in a state where the side guides 72A and 72B guide the width direction of the standard size sheet 3, as shown in FIG. The hooks 86 formed on the standing portions 84 of the operating lever 82 are engaged with the engaging holes 101 of the restricting lever 100 although they are urged in the direction in which they are folded together by the urging force of the tension spring 108. . Therefore, as shown in FIG. 3, the regulating lever 100 and the supporting lever 102 are arranged on the bottom portion 70 in a state of being expanded together without being folded on each other.

  Then, in order to guide the width direction of the sheet 3 having a small width such as a postcard, the side guides 72A and 72B are moved in the guide holes 51A and 51B of the pressure plate 51 toward the center position in the width direction of the sheet cassette 11, respectively. The rack plate 75 on the left side guide 72A side and the rack plate 78 on the right side guide 72B are moved rightward and leftward while rotating the gear wheel 79 in synchronization with each other by the rack teeth 74 and 77, respectively. The Then, immediately before the width between the side guides 72A and 72B becomes the width of the small sheet 3 such as a postcard, the hypotenuse 81A of the trapezoidal operation protrusion 81 formed on the rack teeth 74 is connected to the operation lever 82. It begins to abut against the protrusion 87. Then, when the width between the side guides 72A and 72B becomes the width of the sheet 3 having a small width such as a postcard, the protrusion 87 of the operation lever 82 is formed by the operation protrusion 81 as shown in FIG. Get over from the hypotenuse 81A to the upper side 81B. At this time, the operating lever 82 is rotated around the support shaft 83 in the clockwise direction against the urging force of the toggle spring 88. As a result, the hook portion 86 formed at the upper end of the upright portion 84 is From the engagement hole 101.

  As described above, when the hook portion 86 of the standing portion 84 is disengaged from the engagement hole 101 of the regulating lever 100, the slide lever 105 moves rearward in FIG. 5 along the slide groove of the bottom portion 70 by the biasing force of the pulling spring 108. Is done. As a result, the support lever 102 rises upward as shown in FIG. As a result, the pressure plate 51 located above the support lever 102 is lifted upward.

  With the support lever 102 lifted upward in this way, the number of sheets 3 with a small width such as a postcard that can be stacked on the pressure plate 51 is equal to the sheet upper limit restricting portion 80A of the left side guide 72A and the right side guide 72B. It is regulated by a gap formed between the sheet upper limit regulating unit 80B and the pressure plate 51. As a result, the unnecessary sheets 3 are not forcibly set on the pressure plate 51.

  Next, the lift release mechanism 91 that releases the lift function of the lift mechanism configured as described above will be described with reference to FIGS. As described above, in the state in which the width direction of the sheet 3 having a small width such as a postcard is guided by the side guides 72A and 72B, as shown in FIG. 8, the support lever 102 is as shown in FIG. The pressure plate 51 is raised by the urging force of the tension spring 108, and therefore the pressure plate 51 is lifted upward by the support lever 102.

  At this time, the slide lever 105 coupled to the lower end of the support lever 102 is slid along the slide groove of the bottom portion 70 and moved to the rear side based on the support lever 102 being raised.

  When the sheet cassette 11 is accommodated in the cassette accommodating portion 50 of the laser printer 1, the slider 106 attached to the lower end of the slide lever 105 also moves rearward together with the sheet cassette 11 as shown in FIG. 9. As a result, the slider 106 engages with the engaging portion 107 disposed below the cassette housing portion 50 of the laser printer 1.

  When the sheet cassette 11 is further accommodated in the accommodating portion 50 (inserted backward), as shown in FIG. 10, the slider 106 engages with the engaging portion 107 and moves further rearward. Since the sheet cassette 11 is moved to the rear side in the absence, the slide lever 105 moves to the front side of the sheet cassette 11 along the slide groove. As a result, the support lever 102 is gradually inclined rearward from the state where it is raised against the urging force of the tension spring 108. Thereby, the inclination state of the control lever 100 is gradually moved to a horizontal state.

  At this time, the hook portion 86 formed on the standing portion 34 of the operating lever 82 is engaged with the engaging hole 101 of the regulating lever 100.

  Then, when the sheet cassette 11 is moved backward to the final setting position of the cassette housing portion 50, the sheet cassette 11 is further moved to the rear side with the slider 106 engaged with the engaging portion 107 as shown in FIG. Therefore, both the regulation lever 100 and the support lever 102 are in a horizontal state. During this time, the hook portion 86 is moved within the engagement hole 101 of the restriction lever, but the engagement between the hook portion 86 and the engagement hole 101 is maintained.

  According to the lift release mechanism 91 described above, after the sheet 3 having a small width is set in the sheet cassette 11, when the sheet cassette 11 is accommodated in the cassette accommodating portion 50 of the laser printer 1, the support lever 102 is raised. The platen 51 is moved from the raised state to the horizontal state, whereby the pressure plate 51 is lowered. When the pressure plate 51 is lowered in this way, the plurality of sheets 3 set in the sheet cassette 11 are not pressed against each other, and the friction generated between the sheets 3 is remarkably reduced. . Accordingly, the sheet 3 can be normally taken into the laser printer 1 reliably, and the sheets 3 are separated one by one and prevented from being taken into the laser printer 1 in a state where a plurality of sheets 3 are overlapped. Thus, the sheet 3 can be reliably picked up.

  In order to form an image on the sheet 3 after the sheet cassette 11 is accommodated in the cassette accommodating portion 50 of the laser printer 1 as described above, the lift plate 52 is driven by the rotational driving force applied from the apparatus main body of the laser printer 1. 12, it is rotated counterclockwise around the rear end 53 and lifted upward. As a result, the pressure plate 51 is lifted upward around the rotation support portion 71 via the lift plate 52. In this state, the sheet 3 at the uppermost position of the sheets 3 stacked on the pressure plate 51 is easily picked up by the pickup roller 61.

In the present embodiment, the pressure plate 51 is lifted upward when the side guides 72A and 72B are combined with a sheet 3 having a small width such as a postcard. However, when the size is adjusted to a size other than the postcard, the pressure plate 51 May be configured to be lifted upward.
(Second Embodiment)
Next, a laser printer according to the second embodiment will be described with reference to FIGS.

  Here, the laser printer according to the second embodiment basically has the same configuration as the laser printer 1 according to the first embodiment. Therefore, here, the configuration of the printer according to the second embodiment is described. Among these, for the same configuration as the laser printer 1 according to the first embodiment, the description of the laser printer 1 according to the first embodiment will be referred to, and the description thereof will be omitted, and the laser according to the first embodiment will be omitted. The same components / members in the printer 1 are basically described with the same reference numerals.

  In the laser printer 1 according to the first embodiment described above, the lift mechanism 90 of the pressure plate 51 in the sheet cassette 11 starts from the state in which the width direction of the standard size sheet 3 is guided by the side guides 72A and 72B. When guiding the width direction of the small sheet 3, the side guides 72 </ b> A and 72 </ b> B are moved toward the center position in the width direction of the sheet cassette 11 to engage the hook portion 86 of the operating lever 82 with the restriction lever 100. The support plate 102 is lifted by the urging force of the pulling spring 108 by removing it from the hole 101 and lifting the pressure plate 51.

  On the other hand, in the laser printer 1 according to the second embodiment, the lift mechanism 201 of the pressure plate 51 in the sheet cassette 11 starts from a state in which the width direction of the standard size sheet 3 is guided by the side guides 72A and 72B. When switching to the state in which the width direction of the sheet 3 having a small width is guided, the cam groove 200 and the cam pin are interlocked with the movement of the side guides 72A and 72B toward the center position in the width direction of the sheet cassette 11. By using the interaction with 203, the regulating plate 202 is moved rearward, so that the slide lever 105 is moved rearward by the urging force of the tension spring 108, the support lever 102 is raised, and the pressure plate 51 is raised. This is different from the laser printer 1 according to the first embodiment in the configuration as described above.

  Further, the height at which the lift mechanism 201 raises the support lever 102 and lifts the pressure plate 51 is such that the width of the sheet 3 with a small width such as a postcard is set in the side guides 72A and 72B with the sheet cassette 11 removed from the laser printer 1. It becomes the highest when the state is guided (FIG. 18C), and it becomes the second highest when the side guides 72A and 72B are guided in the width direction of the standard size sheet 3 (FIG. 18). 18 (B)), when the sheet cassette 11 is attached to the laser printer 1, it is configured to be lowest regardless of the positions of the side guides 72A and 72B (FIG. 18A). This is different from the laser printer 1 according to the first embodiment.

  Next, the configuration of the sheet cassette 11 used in the laser printer 1 according to the second embodiment will be described with reference to FIGS.

  As shown in FIGS. 13 and 16, a left side guide 72 </ b> A and a right side guide 72 </ b> B are arranged on the left and right sides of the front side of the sheet cassette 11 so as to be movable in the left and right directions. The side guides 72 </ b> A and 72 </ b> B guide the width direction of the sheet 3 and are configured to be movable with respect to the width size of the sheet 3.

  Further, as shown in FIG. 14, a pressure plate 51 disposed on the bottom portion 70 of the sheet cassette 11 (see FIGS. 19 to 21 and omitted in FIGS. 13 to 17) is located at the front position on the upper edge of the left side guide 72A. A sheet upper limit restricting portion 80A that extends in the horizontal direction and restricts the upper limit of the sheets 3 stacked on the pressure plate is provided. Similarly, a seat upper limit restricting portion 80B is provided at a front position on the upper edge of the right side guide 72B. The number of sheets 3 that can be stacked on the pressure plate 51 is restricted by a gap formed between the sheet upper limit restriction portions 80 </ b> A and 80 </ b> B and the pressure plate 51.

  Here, the moving mechanism of each side guide 72A, 72B is demonstrated based on FIG. 13 thru | or FIG. 13 to 15, the left side guide 72A is integrally formed of resin or the like, and extends from the rear side of the lower end edge of the left side guide 72A toward the central portion in the width direction of the sheet cassette 11. Is formed horizontally, and a rack plate 75 on which rack teeth 74 are formed is provided on the distal end side (right end side) of the extending portion 73.

  A cam groove 200 is formed in the extending portion 73. The cam groove 200 is formed by continuously forming a first straight cam portion 200A, an inclined cam portion 200B, and a second straight cam portion 200C.

  Here, a cam pin 203 erected on the front end of a restriction plate 202 that is arranged to be movable in the front-rear direction on the front side of the rack teeth 74 in the rack plate 75 is loosely fitted in the cam groove 200.

  Similarly to the left side guide 72A, the right side guide 72B is integrally formed of resin or the like, and extends from the front side of the lower edge of the right side guide 72B toward the center in the width direction of the sheet cassette 11. A protruding portion 76 is formed horizontally, and a rack plate 78 on which rack teeth 77 are formed is provided on the leading end side (left end side) of the extending portion 76.

  At the bottom portion 70 of the sheet cassette 11, the gear wheel 79 is rotatably supported at the center position in the width direction of the sheet 3 via the support portion 79 </ b> A while being separated from the side guides 72 </ b> A and 72 </ b> B by the same distance. Gear teeth (not shown) formed on the circumference of the gear wheel 79 are rack teeth 74 formed on the rack plate 75 of the left side guide 72A and racks formed on the rack plate 78 of the right side guide 72B. The teeth 77 mesh with each other.

  The lift mechanism 201 is disposed in the vicinity of the left side of the gear wheel 77, and the lift mechanism 201 has a restriction plate 202. A cam pin 203 that is loosely fitted in the cam groove 200 is erected at the tip of the regulation plate 202, and a long-hole-shaped guide groove 205 that extends in the front-rear direction is formed. A guide pin 206 provided on the bottom 70 of the sheet cassette 11 is loosely fitted in the guide groove 205.

  As shown in FIGS. 19 to 21, the lift mechanism 201 is provided with a slide lever 105.

  As shown in FIG. 19, a slider 106 is provided at the lower end of the slide lever 105. Support shafts 207 are provided on both sides of the upper portion of the side surface of the slide lever 105, and each support shaft 207 supports the end portion of the support lever 102 in a rotatable manner. Ribs 320 are provided on both sides of the lower portion of the side surface of the slide lever 105.

  Here, the relationship between the positions of the side guides 72A and 72B and the height of the pressure plate 51 when the sheet cassette 11 is detached from the laser printer 1 will be described first.

  As shown in FIGS. 13 to 15, when the side guides 72 </ b> A and 72 </ b> B are in a position for guiding the sheet width direction of a standard size sheet 3 (for example, an A4 size sheet), the cam pin 203 of the regulation plate 202 is The first straight cam portion 200A of the cam groove 200 formed in the extending portion 73 is loosely fitted.

  In this state, the regulation lever 100 and the support lever 102 are in a state of being lifted to a predetermined height from the bottom 70 of the sheet cassette 11 by the biasing force of the tension spring 108 as shown in FIG. At this time, the pressure plate 51 is lifted upward to the first height by the support lever 102.

  When a standard size sheet is stacked on the pressure plate when the support lever 102 is in the state shown in FIG. 18B, the weight of the sheet and the force with which the user pushes the sheet are applied to the upper end of the support lever 102. At this time, since the support lever 102 is tilted as shown by a one-dot chain line in FIG. 19, a force is applied to the slider 106 in the direction shown in FIG. However, at this time, as shown by a one-dot chain line in FIG. 19, the rib 320 provided on the side surface of the slide lever 105 is at a height in contact with the bottom plate 70, so that the rib 320 contacts the stopper 310 provided on the bottom plate 70. Then, the slider 106 does not move further forward in FIG. Therefore, the height of the pressure plate 51 can be kept at the first height against the weight of the sheet and the force with which the user pushes the sheet.

  When the side guides 72A and 72B are moved toward the center in the width direction of the sheet cassette 11 in order to guide the width direction of the sheet 3 having a small width such as a postcard size, the left side guide 72A side The rack plate 75 and the rack plate 78 of the right side guide 72B are moved rightward and leftward, respectively, while rotating the gear wheel 79 in synchronization with each other by the rack teeth 74, 78.

  While the side guides 72A and 72B are moved as described above, the first linear cam portion 200A first moves to the right, and the cam pin 206 reaches the left end of the inclined cam portion 200B. During this time, the first straight cam portion 200A only moves in the right direction, and the guide pin 206 is in contact with the rear end portion of the guide groove 205 as shown in FIG.

  In this state, the regulation lever 100 and the support lever 102 maintain the state shown in FIG.

  As the side guides 72A and 72B are further moved, the inclined cam portion 200B moves to the right, and the cam pin 203 moves to the left end portion of the inclined cam portion 200B. At this time, the limiter 201 is moved toward the rear of the sheet cassette 11 by the cam action of the inclined cam portion 200 </ b> B and the cam pin 203. Based on this, as shown in FIG. 18B, the relationship between the regulating lever 100 and the supporting lever 102 is that the regulating lever 100 and the supporting lever 102 are both slightly tilted, and the cam pin 203 is further tilted by the cam portion. When reaching the left end portion of 200B, as shown in FIG. 18C, the regulating lever 100 is further tilted and the support lever 102 is raised to the upright state by the biasing force of the tension spring 108. At this time, the guide pin 206 is moved along the guide groove 205 to the front end portion of the guide groove 205 and is in contact with the front end portion.

  In the state where the support lever 102 is raised upward as described above, the pressure plate 51 located on the upper side of the support lever 102 is raised to the second height higher than the first height, as in the first embodiment. Lifted to.

  When the side guides 72A and 72B are further moved, the width between the side guides 72A and 72B becomes the width of the small sheet 3 such as a postcard as shown in FIG. During this time, the second straight cam portion 200C moves further to the right, and the cam pin 203 moves from the left end portion of the inclined cam portion 200B to the left end portion of the second straight cam portion 200C. At this time, the cam pin 203 is only moved along the second linear cam portion 200C, and the limiter 201 is not moved. At this time, the guide pin 206 remains in contact with the front end portion of the guide groove 205.

  When a small sheet 3 such as a postcard is stacked on the pressure plate when the support lever 102 is in the state of FIG. 18C, the weight of the sheet and the force by which the user pushes the sheet is applied to the upper end of the support lever 102. At this time, as indicated by a one-dot chain line in FIG. 19, the rib 320 provided on the side surface of the slide lever 105 is at a height in contact with the bottom plate 70, so that the rib 30 contacts the stopper 330 provided on the bottom plate 70. The slider 106 does not move further forward in FIG. Therefore, the height of the pressure plate 51 can be kept at the first height against the weight of the sheet and the force with which the user pushes the sheet.

  As described above, when the sheet cassette 11 is detached from the laser printer 1, the support lever 102 is lifted upward, so that the number of sheets 3 that can be stacked on the pressure plate 51 is as follows. It is limited to the number of sheets that can be accommodated in a gap formed between the sheet upper limit restricting portion 80A of the side guide 72A and the sheet upper limit restricting portion 80B of the right side guide 72B and the pressure plate 51.

  Further, the gaps formed between the sheet upper limit restricting portion 80A of the left side guide 72A and the sheet upper limit restricting portion 80B of the right side guide 72B and the pressure plate 51 are the seats of the standard size seat 3 in the side guides 72A and 72B. The side guides 72A and 72B are smaller than the case where the side guides 72A and 72B are in the position for guiding the sheet width direction of the sheet 3 having a size smaller than the standard size. Therefore, the number of sheets 3 smaller than the standard size that can be set on the pressure plate 51 can be smaller than the number of sheets 3 of the standard size that can be set on the pressure plate 51.

  In the mechanism described above, the number of sheets 3 that can be set on the pressure plate 51 in conjunction with changing the positions of the side guides 72A and 72B is arbitrarily set by designing the shape of the cam groove 200 to a preferable shape. It can also be changed.

  For example, in this embodiment, the number of sheets 3 that can be set on the pressure plate 51 by providing two straight portions of the first straight cam portion 200A and the second straight cam portion 200C in the cam groove 200 has a width such as a postcard. The number of sheets corresponding to a small sheet and the number of sheets corresponding to a sheet having a large width such as A4 are changed in two stages. If three straight portions are provided in the cam groove 200, the number of sheets 3 that can be set on the pressure plate 51 is set to a number corresponding to a small width sheet such as a postcard and a medium width sheet such as A5. The number of sheets corresponding to the number of sheets and the number of sheets corresponding to a sheet having a large width such as A4 can be changed in three stages.

  Next, a lift release mechanism 210 that releases the lift function of the lift mechanism 201 of the pressure plate 51 in the laser printer 1 according to the second embodiment will be described.

  That is, when the sheet cassette 11 is detached from the laser printer 1 as shown in FIGS. 19 to 21, the support lever 102 is pulled as shown in FIG. The pressure plate 51 is raised by the urging force of the spring 108. Therefore, the pressure plate 51 is lifted upward by the support lever 102.

  At this time, the slide lever 105 coupled to the lower end of the support lever 102 is slid along the slide groove of the bottom portion 70 and moved to the rear side based on the support lever 102 being raised.

  When the sheet cassette 11 is accommodated in the cassette accommodating portion 50 of the laser printer 1, as shown in FIG. 20, the slider 106 attached to the lower end of the slide lever 105 also moves rearward along the slide groove. As a result, the slider 106 is guided by the slope 110 of the engaging portion 107 disposed below the cassette housing portion 50 of the laser printer 1 and rides on the upper surface of the engaging portion 107 and is lifted upward. 109 is contacted. As a result, the rib 320 provided on the side surface of the slide lever 105 is lifted to a position where it does not contact the stopper 310 and the stopper 330 provided on the bottom plate 70. If the sheet cassette 11 is further accommodated in the cassette accommodating portion 50 of the laser printer 1 from this state, the slider 106 remains at the level of the step 109 of the engaging portion 107, and the sheet cassette 11 moves to the rear side. The slider 106 moves to the front side of the sheet cassette 11 while maintaining the position where the rib 320 does not contact the stoppers 310 and 330 with respect to the sheet cassette 11. As a result, the lower end of the support lever 102 moves to the front side of the sheet cassette 11 against the urging force of the tension spring 108, the support lever 102 tilts to the rear side, and the tilt of the regulating lever 100 approaches a horizontal state.

  Further, when the sheet cassette 11 is moved leftward to the final set position of the accommodating portion 52, the slider 106 remains engaged with the engaging portion 107 as shown in FIG. The sheet cassette 11 is moved to the left while keeping the position where 320 does not contact the stopper 310 and the stopper 330. Then, as shown in FIG. 18A, the slider 106 moves to a position where both the regulation lever 100 and the support lever 102 become horizontal. As a result, the pressure plate is lowered to a third position lower than the first position.

  According to the lift releasing mechanism 210 described above, when the sheet cassette 11 is accommodated in the cassette accommodating portion 50 of the laser printer 1, the support lever 102 is moved from the raised state to the horizontal state. Thus, the pressure plate 51 is lifted to the first height or the second height in conjunction with the positions of the side guides 72A and 72B, and more than either the first height or the second height. Lowered to a lower third height. When the pressure plate 51 is lowered in this way, a gap formed between the sheet upper limit restricting portions 80A and 80B and the pressure plate 51 is widened, so that a plurality of sheets 3 set in the sheet cassette 11 are mutually connected. In addition, the friction generated between the sheets 3 is remarkably reduced. Therefore, the sheet 3 can be reliably picked up. That is, it is possible to prevent the sheets 3 from being taken into the laser printer 1 in a state where a plurality of sheets are overlapped, and to reliably separate the sheets 3 one by one and take them into the laser printer 1.

  In addition, this invention is not limited to the said embodiment, Of course, various improvement and deformation | transformation are possible within the range which does not deviate from the summary of this invention.

DESCRIPTION OF SYMBOLS 1 Laser printer 3 Sheet 5 Image formation part 11 Sheet cassette 50 Cassette accommodating part 51 Pressure plate 70 Bottom part 72A Left side guide 72B Right side guide 80A Sheet upper limit control part 80B Sheet upper limit control part 90 Lift mechanism 91 Lift release mechanism 100 Control lever 102 Support Lever 106 Slider 107 Engaging portion 108 Pulling spring

Claims (4)

Image forming apparatus comprising: a sheet cassette that stores a plurality of sheets; a cassette storage unit that stores the sheet cassette; and an image forming unit that forms an image on a sheet fed from the sheet cassette stored in the cassette storage unit In the device
A pressure plate disposed at the bottom of the sheet cassette and loaded with a plurality of sheets;
A side guide that is provided in the sheet cassette and is movable in accordance with the width size of the sheet while guiding the width direction of the sheet;
A sheet upper limit restricting portion that is provided at a position facing the pressure plate in the side guide and restricts an upper limit of sheets stacked on the pressure plate;
A lift mechanism that lifts the pressure plate in conjunction with the movement of the side guide when the side guide is moved to a position narrower than a predetermined seat width;
An image forming apparatus, comprising: a lift releasing mechanism provided in the cassette housing portion and releasing a lift function of the lift mechanism when the sheet cassette is housed in the cassette housing portion. The lift mechanism is
A lever for lifting the pressure plate;
A spring member for urging the lever in the direction of lifting the pressure plate;
A slider slidable according to the biasing force of the spring member,
The lift release mechanism is
An engaging portion that is provided in the cassette housing portion and engages with the slider when the sheet cassette is housed in the cassette housing portion and lowers the lever against the urging force of the spring member. The image forming apparatus according to claim 1, wherein: Image forming apparatus comprising: a sheet cassette that stores a plurality of sheets; a cassette storage unit that stores the sheet cassette; and an image forming unit that forms an image on a sheet fed from the sheet cassette stored in the cassette storage unit In the device
A pressure plate disposed at the bottom of the sheet cassette and loaded with a plurality of sheets;
A lift mechanism for lifting and holding the pressure plate;
An image forming apparatus, comprising: a lift releasing mechanism provided in the cassette housing portion and operating the lift mechanism to lower the pressure plate when housing the sheet cassette in the cassette housing portion. The lift mechanism is
A lever for lifting the pressure plate;
A spring member for urging the lever in the direction of lifting the pressure plate;
A slider slidable according to the biasing force of the spring member,
The lift release mechanism is
An engaging portion that is provided in the cassette housing portion and engages with the slider when the sheet cassette is housed in the cassette housing portion and lowers the lever against the urging force of the spring member. The image forming apparatus according to claim 3.

Images