JP2011016642A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device having a structure of avoiding inconvenience of impairing proper detection when a positioning projection hitches on an inner surface of a positioning hole, when fitting the positioning projection on the paper feeding cassette side to the positioning hole put in a float state.SOLUTION: A float support base 301 is held in an inclined state of projecting a left end part from a right end part in a state of not fitting the positioning projections 308a and 308b. The float support base rotates with a part near the right end part as the rotational center by following this entrance when entering the positioning hole of the positioning projections. Thus, when fitting the positioning projection on the paper feeding cassette side to the positioning hole of the float support base put in the float state, the positioning projection can be smoothly fitted without hitching on the inner surface of the positioning hole.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus having a configuration in which the size of a sheet stored in a paper feed cassette is detected on the image forming apparatus main body side.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copying machines, printers, facsimiles, and the like have been provided with a sheet feeding device for supplying sheets to an image forming unit, and sheets of various sizes are stacked and stored in the sheet feeding device. Some have a paper cassette that can. In order to record an image in an appropriate range of a sheet fed from the paper cassette, when the paper cassette is mounted on the image forming apparatus main body (hereinafter also referred to as the apparatus main body), It is necessary to make the apparatus main body determine the size of the stored sheet.

  As described above, in order to make the apparatus main body determine the size of the sheet stored in the paper feed cassette, various techniques for transmitting information on the sheet size from the paper feed cassette to the apparatus main body have been proposed. For example, an electrical push switch is provided on the main body side of the apparatus, and a plurality of pressing members (cams) that are displaced by operation according to the sheet size are provided in the paper feed cassette, thereby eliminating the need for electrical components in the paper feed cassette. An image forming apparatus having the above configuration has been proposed (see Patent Document 1).

  In the image forming apparatus described in Patent Document 1, the paper feed cassette is inserted into the apparatus main body while the cam on the paper feed cassette side is rotated according to the size of the sheet in the paper feed cassette. When the paper feed cassette is inserted into the apparatus main body, the cam on the paper feed cassette side is positioned by a positioning mechanism having positioning protrusions with respect to a plurality of push switches on the apparatus main body side. Then, the plurality of push switches arranged on the apparatus main body side are selectively turned on and off by the cam, whereby the size of the sheets stacked in the sheet feeding cassette can be determined on the apparatus main body side.

Japanese Patent Laid-Open No. 08-85634

  In the technique described in Patent Document 1, the electrical push switch has a float configuration with a spring or the like interposed between the apparatus body and the apparatus in order to allow variation in the position between the sheet feeding cassette and the apparatus body. Attached to the substrate holder. Then, the positioning projection provided on the sheet feeding cassette is fitted into the positioning hole of the substrate holder in the float state, so that the sheet feeding cassette is positioned with respect to the apparatus main body. However, although the substrate holder having the positioning hole is in a floating state, the positioning protrusion that is fixed to the paper feed cassette and linearly enters the positioning hole is caught on the inner surface of the positioning hole depending on the angle at the time of fitting. May bite. This phenomenon occurs more prominently when the substrate holder is pushed diagonally by the positioning protrusions. At this time, both of them bite by trying to enter further while the positioning protrusions are caught on the inner surface of the positioning hole. End up. At this time, the cam of the cam holder on the sheet feeding cassette side is not properly positioned with respect to the plurality of push switches, and the sheet size information is not accurately transmitted to the apparatus main body side.

  Therefore, the present invention has a structure that can avoid the inconvenience that the positioning projection is caught on the inner surface of the positioning hole and impairs proper detection when the positioning projection on the sheet feeding cassette side is fitted into the positioning hole in the float state. An object of the present invention is to provide an image forming apparatus including the above.

  In the image forming apparatus main body, the image forming apparatus main body includes a switch unit having a switch unit that detects a size of a sheet stored in the paper feeding cassette, and the paper feeding cassette includes the paper feeding unit when the image forming apparatus main body is mounted on the image forming apparatus main body. In the image forming apparatus including a transmission unit that transmits a size of a sheet in the cassette, the transmission unit includes a positioning protrusion that protrudes toward the switch unit, and the switch unit when the paper cassette is mounted. A switch switching portion that switches according to the sheet size in the cassette, and the switch unit has a positioning hole for fitting the positioning projection at one end portion and the switch portion at the other end portion. The image forming apparatus main body is provided with a support base rotatably supported via a biasing member, and the support base is inserted into the positioning hole in the position. When the fixing protrusion is not fitted, the one end is held in an inclined state protruding from the other end toward the sheet feeding cassette, and when the positioning protrusion is fitted into the positioning hole, the positioning protrusion Is configured to rotate about the part near the other end as the center of rotation following the entry into the positioning hole.

  According to the present invention, the support base is held in an inclined state in which one end portion protrudes from the other end portion when the positioning projection is not fitted, and when the positioning projection enters the positioning hole, it follows this and is closer to the other end portion. It is comprised so that it may rotate centering on this part. As a result, when the paper feeding cassette is mounted, the positioning protrusions that enter the positioning holes of the support table that are held in an inclined state come into contact with the inner surface of the positioning holes and push the support table and rotate it to the switch section. It goes to the set state in which the switch switching unit is brought into contact. For this reason, when the positioning projection on the sheet feeding cassette side is fitted into the positioning hole of the support base in the floated state, the positioning projection fits smoothly without being caught on the inner surface of the positioning hole. Accordingly, it is possible to reliably avoid the inconvenience that the positioning protrusion is caught on the inner surface of the positioning hole and impairs proper detection.

FIG. 3 is a plan view of a sheet feeding cassette in a state where sheets with a narrow sheet size width are stacked. (A) is a perspective view of a size detection lever and its vicinity, (b) is a perspective view of the base end part vicinity of a size detection lever, (c) is a top view of a size detection lever and its vicinity. (A) is a perspective view of a size detection lever and its vicinity, (b) is a perspective view of the base end part vicinity of a size detection lever, (c) is a top view of a size detection lever and its vicinity. (A) is another perspective view of the size detection lever and its vicinity, (b) is a perspective view of the vicinity of the base end of the other size detection lever, (c) is a bottom view of another size detection lever and its vicinity. (A) is another perspective view of the size detection lever and its vicinity, (b) is a perspective view of the vicinity of the base end of the other size detection lever, (c) is a bottom view of another size detection lever and its vicinity. 1 is a cross-sectional view illustrating a schematic configuration of a copier that is an example of an image forming apparatus according to the present invention. (A) is a front view which shows a switch unit, (b) is a top view of a switch unit. FIG. 3 is a plan view showing a state in the middle of mounting the paper feed cassette to the image forming apparatus main body. The perspective view which shows the state of FIG. 8 in the state looked down from diagonally upward. FIG. 3 is a plan view showing a state in which a paper feed cassette is completely attached to the image forming apparatus main body.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the drawings. In the following, the case where the image forming apparatus is a copying machine will be described. However, the present invention is not limited to this, and it is needless to say that the image forming apparatus may be a printer, a facsimile, or a complex machine thereof. FIG. 6 is a sectional view showing a schematic configuration of a copying machine to which the present invention is applied.

  In FIG. 6, reference numeral 100 denotes a copying machine as an image forming apparatus, and 101 denotes a copying machine main body as an image forming apparatus main body. An image reading unit 130 for reading a document D placed on a platen glass 120 a as a document placement table by an automatic document feeder 120 is provided on the upper part of the copying machine main body 101. Below the image reading unit 130, an image forming unit 102 and a sheet feeding device 103 that feeds the sheet S to the image forming unit 102 are provided.

  The image forming unit 102 includes a photosensitive drum 112, a developing device 113, a laser scanner unit 111, and the like. The sheet feeding apparatus 103 includes sheet cassettes 11 and 12 that store sheets S of various sizes and are detachably attached to the copying machine main body 101. The sheet feeding device 103 includes a suction conveyance belt 21 that is a conveyance belt as a sheet feeding unit that feeds the sheets S stored in the sheet feeding cassettes 11 and 12. The configuration for sucking and feeding out the sheet including the suction conveyance belt 21 is unitized.

  Next, an image forming operation of the copying machine 100 having such a configuration will be described. When an image reading signal is output from the control device 500 provided in the copying machine main body 101 to the image reading unit 130, the image reading unit 130 reads an image. Thereafter, a laser beam corresponding to the electrical signal is emitted from the laser scanner unit 111 onto the photosensitive drum 112. At this time, the photosensitive drum 112 is charged in advance, and an electrostatic latent image is formed by irradiating light, and then the electrostatic latent image is developed by the developing unit 113, whereby a toner image is formed on the photosensitive drum. Is formed. On the other hand, when a paper feed signal is output from the control device 500 to the sheet feeding device 103, the sheet S is fed from the paper feeding cassette 11 or the paper feeding cassette 12. Thereafter, the fed sheet S is sent to a transfer unit constituted by the photosensitive drum 112 and the transfer charger 118 in synchronization with the toner image on the photosensitive drum by the registration roller 117.

  Next, the toner image is transferred to the sheet sent to the transfer unit in this way, and then conveyed to the fixing unit 114. Thereafter, the unfixed transfer image is fixed on the sheet S by being heated and pressed by the fixing unit 114. Then, the sheet on which the image is fixed in this manner is discharged from the copying machine main body 101 to the sheet discharge tray 119 by the discharge roller 116.

  Next, the sheet feeding apparatus 103 will be described. FIG. 1 is a plan view showing a sheet feeding cassette 12 provided in the sheet feeding apparatus 103. Since the paper feed cassette 11 has substantially the same configuration as the paper feed cassette 12, the paper feed cassette 12 will be described in detail below. The paper feed cassette 12 is mounted on the copying machine main body 101 so that it can be pulled out in a direction perpendicular to the sheet feeding direction. In FIG. 1, an arrow a indicates a drawing direction in which the paper cassette 12 is pulled out from the copying machine main body 101, and an arrow b indicates a mounting direction in which the paper feeding cassette 12 is mounted on the copying machine main body 101. An arrow c indicates the sheet feeding direction in which the sheets stored in the sheet feeding cassette 12 are fed.

  The paper feed cassette 12 has a bowl-shaped cassette body 12A having an upper opening. The sheet feeding cassette 12 is disposed in the cassette body and has a pair of regulating plates 5 and 6 (hereinafter referred to as side regulating plates) for regulating the position of the side end portion in the width direction orthogonal to the sheet feeding direction. is doing. The sheet feeding cassette 12 has a regulating plate 13 (hereinafter referred to as a trailing end regulating plate) that regulates the position of the trailing end that is the upstream end of the sheet in the sheet feeding direction. The side regulating plates 5 and 6 are disposed on the cassette body 12A so as to be movable in the width direction in accordance with the position of the side edge of the sheet, and the trailing edge regulating plate 13 is arranged in accordance with the position of the trailing edge of the sheet. The cassette body 12A is arranged so as to be movable in the feeding direction. The side regulating plates 5 and 6 can be moved by the same amount of movement in the width direction so as to be separated from or approach each other by a rack and pinion mechanism (not shown).

  The sheet feeding apparatus 103 includes a size detection unit 14 that detects the size of the sheet stored in the cassette body 12A. The size detection unit 14 includes a plurality (two in the present embodiment) of size detection levers 7 and 8 and a switch unit 10 having a plurality (four in the present embodiment) button switches. Yes. Positioning projections 308a and 308b projecting toward the copier main body 101 when stored (mounted) are arranged vertically at the center in the left-right direction in FIG. 1 at the end of the cassette main body 12A where the size detector 14 is located. Is arranged. The size detection levers 7 and 8 are supported by the rotation shaft 9 so that the base end portions 7B and 8B can rotate about the rotation shaft 9 provided on the cassette body 12A. The size detection levers 7 and 8 are opposed to the rear side regulation plate 6 of the pair of side regulation plates 5 and 6, and are opposite to the side on which the sheet of the cassette body 12A is stored with respect to the side regulation plate 6. Is arranged. The size detection levers 7 and 8 are disposed so that the front end portions 7 </ b> A and 8 </ b> A are directed toward the side regulating plate 6 and are inclined with respect to the plate surface of the side regulating plate 6. The size detection levers 7 and 8 are urged in a direction in which the size detection levers 7 and 8 come into contact with the side regulating plate 6 by an urging member (not shown) (eg, a spring). The size detection levers 7 and 8 resist the urging force of an urging member (not shown) due to the pressing of the side restriction plate 6 as the side restriction plate 6 moves to the restriction position according to the size of the sheet. Rotate.

  The switch unit 10 includes a so-called multiple switch in which a plurality of button switches are arranged in a line. In the present embodiment, the switch unit 10 includes a quadruple switch having four button switches. The switch unit 10 has a base end via a float support base 301 described later so that the button switch is turned on / off by the base end portions 7B and 8B when the paper feed cassette 12 is mounted on the copier body 101. Arranged in the copying machine main body 101 so as to face the sections 7B and 8B. FIG. 1 shows a state in which the paper feed cassette 12 is mounted on the copying machine main body 101 and the base end portions 7B and 8B of the size detection levers 7 and 8 are turning on / off the button switches of the switch unit 10. ing. That is, on the base end portions 7B and 8B of the size detection levers 7 and 8, when the paper feed cassette 12 is mounted on the copying machine main body 101, the corresponding button switch of the switch portion 10 is turned ON / OFF according to the rotation position. An operation unit to be turned off is formed. An ON / OFF signal from the button switch of the switch unit 10 is sent to the control device 500 (FIG. 6), and the control device 500 determines the size of the sheet stored in the cassette body 12A based on the signal. .

  In the present embodiment, the size detection lever 7 is provided with two button switches corresponding to the switch unit 10, and there are four combinations of ON / OFF by the two button switches. Accordingly, the two button switches of the switch unit 10 output ON / OFF signals to the control device 500 (FIG. 6) in accordance with the rotational position of the size detection lever 7. Similarly, the size detection lever 8 is provided with two button switches corresponding to the switch unit 10, and there are four combinations of ON / OFF by the two button switches. Accordingly, the two button switches of the switch unit 10 output ON / OFF signals to the control device 500 in accordance with the rotational position of the size detection lever 8. The control device 500 determines the sheet size based on the combination of ON / OFF of these four button switches.

  By the way, in the present embodiment, the size detection levers 7 and 8 are formed with different lengths from the rotation shaft 9 serving as a rotation fulcrum to the distal end portions 7A and 8A. When the sheets of various widths that can be stored in the cassette main body 12A are classified into the large size and the small size, the size detection lever 8 can detect other large size sheets so that the large size sheet can be detected. The length is shorter than 7. That is, when a small size sheet is stored in the cassette body 12A, the size detection lever 8 does not contact the side regulating plate 6 and a large size sheet is stored as shown in FIG. Only when is it pressed by the side regulating plate 6 to rotate.

  When the large size sheet is stored in the cassette body 12A, the size detection lever 7 has a short distance between the side regulating plate 6 and the rotation fulcrum of the size detecting lever 7, and the amount of movement of the side regulating plate 6 is small. Therefore, the rotation amount (rotation angle) of the size detection lever 7 is small. On the other hand, the size detection lever 8 is shorter in length than the size detection lever 7 when a large sized sheet is stored in the cassette body 12A. The amount of rotation is larger than that of the lever 7. Therefore, by providing a plurality of size detection levers 7 and 8 having different lengths, it becomes possible to detect sheets of various widths widely existing from small to large sizes, and the detection accuracy of sheets of various sizes is improved. improves.

  Further, in the present embodiment, the side restriction plate 6 amplifies the amount of rotation of the size detection lever 7 that contacts the size detection lever 7 and rotates as the side restriction plate 6 moves to the restriction position. The protrusion 61 which is a part is provided (refer FIG. 2, FIG. 3). This “amplification” means that even if the side restricting plate 6 has the same movement amount, the rotation angle of the size detecting lever 7 decreases as the side restricting plate 6 moves and becomes closer to the pivot point of the size detecting lever 7. This means that the reduction rate of the rotation angle is reduced. That is, even if the side regulating plate 6 approaches the size detection lever 7, the rotation amount of the size detection lever 7 is made larger than usual. The protrusion 61 separates the size detection lever 7 from the side regulation plate 6 in accordance with the movement of the side regulation plate 6 in a direction approaching the pivot point of the size detection lever 7 when the size detection lever 7 comes into contact. And the amount of rotation of the size detection lever 7 is amplified. On the other hand, the protrusion 61 moves the size detection lever 7 to the side restriction plate 6 in accordance with the movement of the side restriction plate 6 away from the rotation fulcrum of the size detection lever 7 when the size detection lever 7 contacts. It is rotated in the direction of approaching, and the amount of rotation of the size detection lever 7 is amplified.

  Further, the side restriction plate 6 has a protrusion 62 which is an amplifying part that amplifies the amount of rotation of the size detection lever 8 that abuts on the size detection lever 8 and rotates as the side restriction plate 6 moves to the restriction position. (See FIGS. 4 and 5). The protrusion 62 separates the size detection lever 8 from the side restriction plate 6 in accordance with the movement of the side restriction plate 6 in a direction approaching the pivot point of the size detection lever 8 when the size detection lever 8 abuts. And the amount of rotation of the size detection lever 8 is amplified. On the other hand, the protrusion 62 moves the size detection lever 8 to the side restriction plate 6 in accordance with the movement of the side restriction plate 6 away from the rotation fulcrum of the size detection lever 8 when the size detection lever 8 contacts. It is rotated in the direction of approaching, and the amount of rotation of the size detection lever 8 is amplified.

  First, the operation of the size detection lever 7 will be described. FIG. 2 is an explanatory diagram illustrating a state of the size detection lever 7 when a sheet having a width A classified as a small size is stored in the cassette body 12A. In FIG. 2, the size detection lever 8 and the button switch that is turned ON / OFF are not shown.

  When a sheet having a width A classified as a small size is stored in the cassette body 12A, the tip 7A of the size detection lever 7 slides on the protrusion 61 as shown in FIGS. It is not in contact but is in sliding contact with the side regulating plate 6. The base end portion 7B of the size detection lever 7 is formed with an operation portion 70 including projections 72 and 73. The projections 72 and 73 of the size detection lever 7 are switch portions as shown in FIG. Ten two button switches 10a and 10b are pressed. That is, the two button switches 10a and 10b are turned on. Thereby, it is detected that the sheet stored in the cassette body 12A is the size of the width A.

Figure 3 is an explanatory view showing a state of the size detecting lever 7 when the sheet width A + 2 × L ₁ is classified into a small size is contained in the cassette body 12A. In FIG. 3, the size detection lever 8 and the button switch that is turned ON / OFF are not shown. The sheet of width A + 2 × L ₁ is larger in size than the sheet of width A by width 2 × L ₁ . Thus, the side regulating plates 6, when a reference restriction position for restricting the side edge of the sheet width A, moves the moving amount L ₁ in the size detecting lever 7 side. Here, when the size difference between the sheet having the width A and the sheet having the width 2 × L ₁ is slight, the amount of rotation of the size detection lever is merely determined by sliding the tip of the size detection lever to the side regulating plate. Will be small.

  Therefore, in the present embodiment, as shown in FIG. 3A, the side regulating plate 6 is provided with a protrusion 61, and the rotation amount of the size detection lever 7 is amplified by the protrusion 61. The protrusion 61 protrudes from the side regulating plate 6 on the size detection lever side. As shown in FIG. 3C, the protrusion 61 has a sliding contact portion 61 a with which the tip end portion 7 </ b> A of the size detection lever 7 is in sliding contact, and is slid so as to amplify the rotation amount of the size detection lever 7. The amount of protrusion of the contact portion 61a from the side regulating plate 6 changes. Specifically, the amount of protrusion is such that the size detection lever 7 is rotated in a direction away from the side restriction plate 6 as the side restriction plate 6 moves in a direction approaching the rotation fulcrum of the size detection lever 7. It has changed.

In FIG. 3C, the two-dot chain line indicates the side regulating plate 6 when the sheet having the size of the width A is moved to the regulating position for regulating the sheet. Moving amount L ₁ moves the side regulating plates 6 relative to the regulating position for regulating the sheet size of the width A of the size detecting lever 7 side, the distal end portion 7A of the size detecting lever 7, the sliding contact portion 61a of the protrusion 61 Slidably contacts and moves along the slidable contact portion 61a. Thus, the size detecting lever 7 is rotated in the same rotation amount as moved to the position shown without side regulating plate projections 61 in dashed lines in moving distance L greater amount of movement L ₂ than _1. That is, the rotation amount of the size detection lever 7 is amplified by the protrusion 61. In this way, the tip 7A of the size detection lever 7 is in sliding contact with the protrusion 61 and the size detection lever 7 rotates in the direction of the arrow in FIG. 3C, so that the size detection lever as shown in FIG. 7 is disengaged from the button switch 10b and the pressure is released. That is, the button switch 10a is turned on and the button switch 10b is turned off. Thereby, the detected that the sheet contained in the cassette body 12A is sized width A + 2 × L _1.

  Next, the operation of the size detection lever 8 will be described. FIG. 4 is an explanatory diagram illustrating a state of the size detection lever 8 when a sheet having a width B classified as a large size is stored in the cassette body 12A. In FIG. 4, the size detection lever 7 and the button switch that is turned on and off are not shown.

  When a sheet having a width B classified as a large size is stored in the cassette body 12A, the front end 8A of the size detection lever 8 slides on the side regulating plate 6 as shown in FIGS. Touching. An operation unit 80 including projections 82 and 83 is formed at the base end 8B of the size detection lever 8, and the projections 82 and 83 of the size detection lever 8 are two button switches 10c and 10d of the switch unit 10. (See FIG. 4B). That is, the two button switches 10c and 10d are turned on. As a result, it is detected that the sheet stored in the cassette body 12A has a width B size.

  The operation units 70 and 80 constitute a switch switching unit that switches the switch unit 10 according to the sheet size in the sheet cassette 12 when the sheet cassette 12 is mounted. Further, a sheet feeding cassette 12 transmits a sheet size in the sheet feeding cassette 12 when the sheet feeding cassette 12 is mounted on the copying machine main body 101 from positioning projections 308a and 308b, which will be described later, and operation units 70 and 80 as switch switching units. A transmission unit provided in the paper cassette 12 is configured.

Figure 5 is an explanatory view showing a state of the size detecting lever 8 when the sheet width B + 2 × L ₃ classified into large size is contained in the cassette body 12A. In FIG. 5, the size detection lever 7 and the button switch that is turned ON / OFF are not shown. A sheet of width B + 2 × L ₃ is larger in size than a sheet of width B by a width 2 × L ₃ . Thus, the side regulating plates 6, when a reference restriction position for restricting the side edge of the sheet width B, and the movement amount of movement L ₃ in size detecting lever 8 side. Here, when the size difference between the sheet of width B and the sheet of width 2 × L ₃ is slight, the amount of rotation of the size detection lever is merely determined by sliding the tip of the size detection lever to the side regulating plate. Will be small.

Therefore, in the present embodiment, as shown in FIG. 5A, the side regulating plate 6 is provided with a protrusion 62, and the rotation amount of the size detection lever 8 is amplified by the protrusion 62. The protrusion 62 protrudes from the side regulating plate 6 on the size detection lever side. As shown in FIG. 5C, the protrusion 62 is provided so as to abut on a protrusion 8 </ b> C that is a portion closer to the rotation fulcrum than the tip 8 </ b> A of the size detection lever 8. In FIG. 5C, the two-dot chain line indicates the side regulating plate 6 when the sheet having the size of the width B is moved to the regulating position that regulates the sheet. Moving amount L ₃ moves the side regulating plates 6 relative to the restricted position for restricting the size of the sheet width B of the size detecting lever 8 side, in contact with the protruding portion 8C protrusion 62 of the size detecting lever 8, the tip The portion 8A is separated from the side regulating plate 6. As a result, the size detection lever 8 is rotated by the same rotation amount as when the side regulating plate without the protrusion 62 is moved to the position indicated by the broken line with the movement amount L ₄ larger than the movement amount L ₃ . That is, the rotation amount of the size detection lever 8 is amplified by the protrusion 62.

As described above, the size detection lever 8 rotates in the direction indicated by the arrow in FIG. 5C when the projection 8C of the size detection lever 8 contacts the projection 62, and the size detection is performed as shown in FIG. 5B. The protrusion 83 of the lever 8 is released from the button switch 10d, and the pressing is released. That is, the button switch 10c is turned on and the button switch 10d is turned off. Thereby, the detected that the sheet contained in the cassette body 12A is sized width B + 2 × L _3.

  As described above, the two size detection levers 7 and 8 selectively select the button switches 10a, 10b, 10c, and 10d of the switch unit 10 as the side restriction plate 6 moves to the restriction positions corresponding to various sizes. ON / OFF. And the signal of a different pattern is output from the switch part 10 to the control apparatus 500 (FIG. 6). Then, the size of the sheets stored in the sheet feeding cassette 12 is determined by the control device 500.

  Next, the configuration of the switch unit 15 that supports the switch unit 10 of the size detection unit 14 in a floated state and the periphery thereof will be described in detail. The switch unit 15 is provided in the copying machine main body 101 and includes a switch unit 10 that detects the size of the sheet S stored in the sheet feeding cassette 12. That is, as shown in FIG. 7, the switch unit 15 includes a float support base 301 as a support base that supports the switch unit 10, pressurizing springs 302a, 302b, and 302c as biasing members, and the copier body 101 side. And a regulation table 303 attached to the vehicle. Each of the pressure springs 302a, 302b, and 302c is a coil spring that biases the float support base 301 toward the paper feed cassette 12 entering the copying machine main body 101 side.

  The float support base 301 is generally formed in a substantially rectangular shape when viewed from the front, and is positioned at the left end portion in the drawing so as to face the positioning protrusions 308a and 308b arranged vertically at the center portion at the end portion on the paper feed cassette 12 side. Positioning holes 301a and 301b are formed vertically. That is, the float support base 301 has positioning holes 301a and 301b for fitting the positioning protrusions 308a and 308b at the left end (one end) in the drawing. The float support base 301 includes the pressure springs 302a to 302c on the copier main body 101 side (image forming apparatus main body side) in a state where the switch portion 10 is provided at the right end portion (the other end portion) together with the positioning holes 301a and 301b. It is supported so that it can rotate freely.

  As will be described in detail later, the positioning protrusions 308a and 308b that protrude toward the switch unit 15 are formed so that they gradually become thinner toward the front in the entry direction of the paper feed cassette 12, and the tip is rounded. . The inner peripheral surfaces of these positioning holes 301a and 301b are formed along a direction perpendicular to the front surface of the float support base 301 (the surface facing the sheet cassette 12 side), as shown in FIG. 7B. . Therefore, when the sheet feeding cassette 12 is not mounted, as shown in FIG. 8, the positioning holes 301a and 301b have an angle (α in FIG. 7B) with respect to the entering positioning projections 308a and 308b. Configured. Further, in the float support base 301, a hole 306 is formed in the center portion in FIG. 7A, and the switch portion 10 extends along the vertical direction in a state where the front end is faced in the notched portion of the right end portion. Is installed. The hole 306 is formed larger than the locking portions 304a and 304b of the restricting projection 304 so as to have a backlash.

  One end of each of the pressure springs 302 a, 302 b, 302 c is supported on the regulation base 303, and the other end of each of the pressure springs 302 a, 302 b, 302 c is supported on the float support base 301. Among these, the pressurizing springs 302b and 302c rotate the float support base 301 beyond a certain angle (α in FIG. 7B) by engagement of a restriction projection 304 and a locking portion 304a and 304b described later. It is compressed to a state where it is restricted so as not to move. The angle α (FIG. 7B), which is the inclination of the float support base 301 when the paper feed cassette 12 is not mounted, always supplies the sheet even if the positioning holes 301a and 301b have variations such as component tolerances. It is defined so as to face the device 103 (FIG. 6). Between the positioning holes 301a and 301b on the back surface of the float support base 301, a support portion 301c for stably supporting the other end of the pressure spring 302a is provided.

  In other words, the restricting base 303 is provided with a restricting protrusion 304 that protrudes toward the float support base 301, and the restricting protrusion 304 is a locking portion that is formed long in the vertical direction of FIG. have. The upper and lower locking portions 304a and 304b of the locking portion are formed as inclined surfaces as shown in FIGS. In FIG. 7B, the angle formed between the front surfaces of the locking portions 304 a and 304 b and the back surfaces thereof is set to be the same as the angle α of the float support base 301. When the sheet feeding cassette 12 is not mounted, the float support table 301 is in contact with the back surfaces of the locking portions 304a and 304b so that the float support table 301 is located on the back side of the hole 306. A stopper surface 305 is formed to be held in an inclined state.

  As shown in FIG. 8, an abutting portion 309 is formed between the positioning projections 308 a and 308 b and the operation portions 70 and 80 at the end of the sheet feeding cassette 12. Each of the positioning protrusions 308a and 308b has a main body portion 308d having a size smaller than the inner diameter of the corresponding positioning holes 301a and 301b, and a tapered portion 308e that gradually narrows from the main body portion 308d toward the tip. The positioning protrusions 308a and 308b contact the periphery of the positioning holes 301a and 301b after inserting the respective tapered portions 308e into the corresponding positioning holes 301a and 301b, respectively, and hold the switch unit 15 in the set state. have. Here, the set state means a mounted state of the paper feed cassette 12 in which the operation units 70 and 80 as switch switching units are brought into contact with the switch unit 10. The positioning protrusions 308a and 308b abut on the rear end of the main body 308d and the float support base 301 in which the main body 308d is fitted in the positioning holes 301a and 301b. Thus, the set state is stably maintained. At this time, the positioning step 309c is the same as the butting portion 309 so that the abutting portion 309 presses and supports the front surface of the float support base 301 (the surface facing the paper feed cassette 12) together with the positioning step portion 308c. It is formed at a height (the same amount of protrusion).

  As described above, in the float support base 301, when the positioning protrusions 308a and 308b are not fitted in the positioning holes 301a and 301b, the left end portion (one end portion) protrudes from the right end portion (the other end portion) toward the sheet feeding cassette. Held in an inclined state. When the positioning protrusions 308a and 308b are fitted in the positioning holes 301a and 301b, the float support base 301 follows the approach of the positioning protrusions 308a and 308b into the positioning holes 301a and 301b and moves toward the right end (the other end). Rotate around the center of rotation. Thereby, the set state of FIG. 10 in which the operation units 70 and 80 are brought into contact with the switch unit 10 is obtained. Here, the “inclined state” means that the plane including the opening portions of the positioning holes 301a and 301b (surface facing the positioning protrusions 308a and 308b) is perpendicular to the protruding direction of the positioning protrusions 308a and 308b. The state of leaning.

That is, when the paper feed cassette 12 is not attached to the copying machine main body 101, the stopper surface 305 of the float support base 301 comes into contact with the back surfaces of the locking portions 304a and 304b, and the float support base 301 is shown in FIG. It is in the inclined state shown. The spring forces of the pressure springs 302a to 302c in this state are W1, W2, and W3, respectively, and the distance from the restricting projection 304 to the pressure positions of the pressure springs 302a to 302c in the direction of FIG. Are set so as to satisfy the following expression (1).
M1 × W1≈M2 × W2 + M3 × W3 (1)
With this setting, the float support base 301 is stably stopped at the position shown in FIG. 7B when the paper feed cassette 12 is not mounted.

  When the paper feeding cassette 12 inserted into the copying machine main body 101 approaches the switch unit 15 (FIGS. 8 and 9), first, the positioning protrusions 308a and 308b are positioned in the positioning holes 301a and 301b of the switch unit 15. Start to touch the inner surface. Then, the float support base 301 resists the left end portion of the float support base 301 against the pressure spring 302a by the frictional force generated when the tapered portions 308e of the positioning protrusions 308a and 308b are slidably contacted with the inner peripheral surfaces of the positioning holes 301a and 301b. Then, it is pushed into the regulation table 303 side. For this reason, the float support base 301 rotates in the direction indicated by the arrow g in FIG. 8 with the portion (the portion closer to the right end) where the stopper surface 305 abuts (engages) the back surfaces of the locking portions 304a and 304b as the rotation center. Be moved. Further, the positioning step portion 308c and the abutting portion 309 come into contact with the front surface of the float support base 301 while the inner peripheral surfaces of the positioning holes 301a and 301b and the outer peripheral surfaces of the positioning projections 308a and 308b are parallel to each other. The mutual position with the paper cassette 12 is determined. Then, until the sheet feeding cassette 12 enters the normal position with respect to the copying machine main body 101, the float support base 301 is also integrally rotated, whereby the set state of FIG. 10 is obtained.

  In the above description, after the tapered portions 308e of the tapered positioning protrusions 308a and 308b enter, the main body portion 308d and the inner peripheral surfaces of the positioning holes 301a and 301b are substantially parallel to each other, so Is extremely small. Therefore, even if the pressure springs 302a to 302c have a weak spring force, the positioning protrusions 308a and 308b are inserted into the positioning holes 301a and 301b in a very stable state, and the feeding cassette 12 is placed in the copying machine main body. 101 can be stored. In the present embodiment, the size detection unit 14 is applied to the sheet size detection switch unit 15. However, for example, the size detection unit 14 may be applied to positioning of a float unit that needs to be positioned.

  As described above, according to the present embodiment, the float support base 301 is held in the aforementioned inclined state when the positioning protrusions 308a and 308b are not fitted, and when the positioning protrusions 308a and 308b enter the positioning holes 301a and 301b. Follow this. And the float support stand 301 rotates centering | focusing on the contact part of the stopper surface 305 and latching | locking part 304a, 304b. Thus, when the paper feed cassette 12 is mounted on the copying machine main body 101, the positioning protrusions 308a and 308b that enter the positioning holes 301a and 301b of the float support base 301 that are held in an inclined state in advance are the inner surfaces of the positioning holes 301a and 301b. To touch. Then, the positioning protrusions 308a and 308b go to the set state while pushing and rotating the float support base 301. Therefore, when the positioning projections 308a and 308b are fitted into the positioning holes 301a and 301b of the float support base 301 in the float state, the positioning projections 308a and 308b are smoothly fitted without being caught on the inner surfaces of the positioning holes 301a and 301b. be able to. Thereby, it is possible to reliably avoid the inconvenience that the positioning protrusions 308a and 308b are caught on the inner surfaces of the positioning holes 301a and 301b to impair proper detection.

DESCRIPTION OF SYMBOLS 10 ... Switch part, 12 ... Paper feed cassette, 15 ... Switch unit, 70, 80 ... Transmission part, Switch switching part (operation part), 100 ... Image forming apparatus (copier), 101 ... Image forming apparatus main body (copier) Main body), 301 ... Support base (float support base), 301a, 301b ... Positioning hole, 308a, 308b ... Transmission part (positioning projection), 308c ... Positioning step part, 308d ... Main body part, 308e ... Taper part, S ... Sheet

Claims (3)

The image forming apparatus main body includes a switch unit having a switch unit that detects a size of a sheet stored in the paper feeding cassette, and the sheet in the paper feeding cassette is mounted on the paper feeding cassette when the image forming apparatus main body is mounted. In an image forming apparatus including a transmission unit that transmits the size of
The transmission unit includes a positioning projection that protrudes toward the switch unit, and a switch switching unit that switches the switch unit according to the sheet size in the sheet feeding cassette when the sheet feeding cassette is mounted.
The switch unit has a positioning hole for fitting the positioning protrusion at one end portion, and is rotatable to the image forming apparatus main body side via a biasing member in a state having the switch portion at the other end portion. With a supported support,
When the positioning protrusion does not fit into the positioning hole, the support base is held in an inclined state in which the one end protrudes toward the sheet feeding cassette from the other end, and the positioning protrusion is in the positioning hole. When fitting, it is configured to follow the entry of the positioning protrusion into the positioning hole and rotate around the other end portion as a rotation center.
An image forming apparatus. The positioning protrusion has a main body portion having a size smaller than the inner diameter of the positioning hole, and a tapered portion gradually narrowing from the main body portion toward the tip.
The image forming apparatus according to claim 1. The positioning projection has a positioning step portion projecting outward from the main body portion at the rear end of the main body portion, and the positioning step portion is brought into contact with the support base in which the main body portion is fitted into the positioning hole. To maintain a set state in which the switch switching unit is brought into contact with the switch unit,
The image forming apparatus according to claim 2.

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