JP2009202962A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide means for preventing erroneous detection of a paper size in an image forming device with both of a constitution for detecting the paper size of a recording paper housed in a paper-feeding cassette with a size dial, and a constitution for moving the paper-feeding cassette upward and downward immediately before the cassette is positioned to an insertion position. <P>SOLUTION: This image forming device 1 comprises a paper-feeding cassette 3 installed so as to be able to be inserted into and pulled out from a device body 2, an auxiliary roller 6 contacting a bottom of the paper-feeding cassette 3, a positioning concave groove 27 formed at the bottom of the paper-feeding cassette 3 in an arc-like shape and fitted with the auxiliary roller 6, a paper size sensor 7 provided so that a sensor filler 15 can be projected from a sensor body 14 installed movably upward and downward inside the device body 2, a sensor contact part 29 projecting from the paper-feeding cassette 3 contacting the paper size sensor 7 from below, and a filler operation part 26 installed to the paper-feeding cassette 3 and operating the projection of the sensor filler 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that uses a size dial to detect the size of a recording sheet stored in a paper feed cassette, and is particularly configured to move up and down immediately before the paper feed cassette is positioned at an insertion position. The present invention relates to an image forming apparatus.

  In an image forming apparatus that is configured as a printer, a copier, a facsimile, or the like and forms an image on recording paper, the recording paper to be supplied to an image forming unit provided inside the apparatus main body is stored in a paper feeding cassette. The paper feed cassette is provided so as to be inserted into and withdrawn from the apparatus main body. Here, as a method of detecting the paper size of the recording paper stored in the paper feed cassette, a method of providing a dedicated paper feed cassette for each paper size is conventionally used. According to this method, the number of paper feed cassettes increases as the type of paper size increases, and there is a problem that the image forming apparatus is increased in size. As another method capable of detecting the paper size of the recording paper while preventing such a problem, a method using a size dial has been conventionally used.

  FIG. 10 is a schematic perspective view showing the configuration of the lower part of the front surface of the image forming apparatus 70 using the size dial according to the conventional example (see Patent Document 1). In this image forming apparatus 70, a paper feed cassette 72 for storing recording paper is provided in an apparatus main body 71 that accommodates an image forming unit (not shown) so that it can be inserted and pulled out. A size dial 74 is turnably provided on the side surface of the main body 71 of the front cover 73 constituting the paper feed cassette 72. Although not shown in detail in FIG. 10, the size dial 74 has filler receiving grooves formed at predetermined intervals on the surface on the apparatus main body 71 side, and various paper sizes are indicated on the surface opposite to the apparatus main body 71. The letters are listed. On the other hand, a paper size sensor 75 for detecting the paper size of the recording paper stored in the paper feed cassette 72 is provided at a position facing the size dial 74 in the apparatus main body 71. The paper size sensor 75 includes a box-shaped sensor main body 76 attached in a fixed state with respect to the apparatus main body 71, and a plurality of sensor fillers 77 provided so as to be able to protrude from the sensor main body 76. Yes.

  In the image forming apparatus 70 configured as described above, after the user pulls out the paper feed cassette 72 to store the recording paper, the user turns the size dial 74 to display characters indicating the paper size of the recording paper stored in the paper feed cassette 72. Is adjusted so that it can be seen through the display window 78 formed on the front cover 73, and then the paper feed cassette 72 is inserted into the apparatus main body 71. When the paper feed cassette 72 is inserted into the apparatus main body 71, as shown in FIG. 11A, a part of the sensor filler 77 of the paper size sensor 75 is pressed by the size dial 74 and is immersed inside the sensor main body 76. Then, the other remaining parts are accommodated in the dial accommodating groove of the size dial 74, so that they protrude from the sensor body 76. The paper size of the recording paper stored in the paper feed cassette 72 is determined by the combination of the immersion and protrusion of the sensor filler 77.

  By the way, in the image forming apparatus in which the paper feeding cassette is provided so as to be able to be inserted into and pulled out from the apparatus main body as described above, the paper feeding cassette can be smoothly inserted and pulled out inside the apparatus main body. In some cases, an auxiliary roller for assisting insertion and withdrawal in contact with the bottom of the sheet feeding cassette is rotatably provided. However, when this auxiliary roller is provided, the paper feed cassette inserted into the apparatus main body is likely to be misaligned, so it is necessary to position it so that it cannot move at the position where the paper feed cassette is inserted. Therefore, an arc-shaped positioning groove that fits into the auxiliary roller is formed at the bottom of the paper cassette, and when the paper cassette is inserted into the main body, this positioning groove is fitted into the auxiliary roller. A configuration in which the sheet feeding cassette is positioned by adopting this method has been conventionally employed.

  FIG. 12 is a schematic longitudinal sectional view showing the structure around the sheet feeding cassette 81 in particular, in the image forming apparatus 80 according to the conventional example provided with auxiliary rollers and positioning concave grooves. In this image forming apparatus 80, an auxiliary roller 83 is rotatably provided at a position inside the apparatus main body 82 from the outside of the apparatus, and on the front cover 84 side position at the bottom of the sheet feeding cassette 81. A convex arcuate positioning groove 85 is formed. According to such a configuration, when the paper feed cassette 81 is inserted along the guide rail 86 provided inside the apparatus main body 82, the edge 87 of the positioning groove 85 is supported as shown in FIG. 12A. After the contact with the roller 83, the sheet cassette 81 gradually floats until the edge 87 reaches the top of the auxiliary roller 83 as shown in FIG. 12B. When the paper feed cassette 81 is further inserted from the state shown in FIG. 12B, the paper feed cassette 81 gradually sinks as shown in FIG. 12C, and the positioning groove 85 is fitted into the auxiliary roller 83. As a result, the paper feed cassette 81 is positioned.

Japanese Patent Laid-Open No. 9-304982

  However, in the conventional image forming apparatus 70 that detects the paper size of the recording paper stored in the paper feed cassette 72 with the size dial 74, the paper feed cassette 72 is positioned at the insertion position as in the conventional image forming apparatus 80. If it is configured to move up and down immediately before, the paper size of the recording paper may be erroneously detected. More specifically, when the paper feed cassette 72 is slightly lifted just before the insertion position, the uppermost sensor filler 77 that is supposed to be pressed into the sensor main body 76 by the size dial 74 as shown in FIG. 11B, the third sensor filler 77 is accommodated in the filler accommodating groove 79 of the size dial 74, and when the paper feed cassette 72 sinks from this state, the top sensor filler 77 and the third from the top. The sensor filler 77 is housed in the filler housing groove 79 in a bent state by being pressed by the size dial 74 as shown in FIG. 11C. Accordingly, the uppermost sensor filler 77 that should be detected in the state of being immersed in the sensor main body 76 and the third sensor filler 77 from the top are detected in a state of protruding from the sensor main body 76. The wrong paper size is detected.

  The present invention has been made in view of such problems, and has a configuration in which the size of a recording sheet stored in a paper feed cassette is detected by a size dial, and immediately before the paper feed cassette is positioned at an insertion position. In an image forming apparatus having a configuration that moves up and down, a means for preventing erroneous detection of the paper size is provided.

  In order to achieve the above object, an image forming apparatus according to the present invention is provided so as to be able to be inserted into and withdrawn from an apparatus main body that accommodates an image forming unit, and to supply recording paper to be supplied to the image forming unit. A paper cassette, an auxiliary roller that is rotatably provided inside the apparatus main body and abuts the bottom of the paper feed cassette to assist insertion and withdrawal, and is formed in an arc shape at the bottom of the paper feed cassette The sensor filler protrudes and descends from a positioning concave groove for positioning the paper feeding cassette at the insertion position by fitting into the auxiliary roller, and a sensor main body provided in the apparatus main body so as to be movable up and down. A paper size sensor for determining the paper size of the recording paper stored in the paper feed cassette by detecting the protruding or immersed state of the sensor filler. A sensor abutting portion that protrudes from the paper feed cassette and abuts against the paper size sensor from below, and is provided on the paper feed cassette so as to face the apparatus main body. And a filler operation unit for operating the sensor filler to move in and out as it is pulled out.

  In the image forming apparatus according to the present invention, a positioning boss protrudes from the sensor body of the paper size sensor, and a long hole is formed in the apparatus body, and the positioning boss is inserted through the long hole. The paper size sensor is provided in the apparatus main body so as to be movable up and down.

  The image forming apparatus according to the present invention includes a pressing member that presses the sensor body of the paper size sensor downward.

  According to the image forming apparatus of the present invention, even if the sheet feeding cassette moves up and down immediately before the positioning concave groove is fitted to the auxiliary roller and positioned, the sheet size sensor follows the sheet feeding cassette. Also move up and down. Therefore, there is no error in the operation of the sensor filler by the filler operation unit, so that the paper size of the recording paper stored in the paper feed cassette can be accurately determined regardless of the vertical movement of the paper feed cassette.

  According to the image forming apparatus of the present invention, when the paper size sensor does not receive an upward pressing force from the paper feed cassette, the positioning boss is positioned at the lowest position of the long hole by its own weight. Positioned. When the paper size sensor receives an upward pressing force due to the floating of the paper feed cassette, the positioning boss moves upward along the elongated hole, so that the paper size sensor follows the paper feed cassette. Furthermore, when the paper size sensor is released from the upward pressing force by sinking the paper cassette, the positioning boss moves downward along the elongated hole by its own weight, thereby following the paper cassette. Sink. Thus, the paper size sensor can be provided in the apparatus main body so as to be movable up and down with a simple configuration.

  Further, according to the image forming apparatus of the present invention, the paper size sensor receives the downward pressing force from the pressing member. Therefore, when the paper size sensor does not receive the upward pressing force from the paper feeding cassette, and from the paper feeding cassette When released from the upward pressing force, the paper size sensor is reliably positioned with the positioning boss at the lowest position of the slot.

  First, the configuration of an image forming apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view illustrating an appearance of an image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 is a copy facsimile multifunction machine having a document copying function, a facsimile communication function, an Internet communication function, and the like, and an image is recorded on a recording sheet based on image data read from a document or image data received by facsimile. An image forming unit (not shown) to be formed is accommodated inside the apparatus main body 2. A paper feed cassette 3 for storing a standard size recording paper to be supplied to the image forming unit is provided at the lower front of the apparatus main body 2 so as to be inserted and pulled out.

  FIG. 2 is a view showing the lower front portion 4 of the apparatus main body 2 constituting the image forming apparatus 1 shown in FIG. 1, and shows a state in which one of the paper feed cassettes 3 is pulled out. Inside the apparatus main body 2, a guide rail 5 extends along the insertion and withdrawal directions of the paper feed cassette 3, and an auxiliary roller 6 is provided close to the end of the guide rail 5 on the front side of the apparatus. . A paper size sensor 7 is provided obliquely above the auxiliary roller 6, and a blind cover 8 is provided to cover various members such as the paper size sensor 7.

  The guide rail 5 is for guiding insertion and withdrawal of the paper feed cassette 3 into the apparatus main body 2. The guide rail 5 is made of metal or the like, and as shown in FIG. 2, the flat receiving surface 9 that receives the bottom portion of the paper feed cassette 3 and the left and right end portions of the paper feed cassette 3 are in contact with each other and shifted laterally. And a regulating surface 10 that regulates the above.

  The auxiliary roller 6 is for smooth insertion and withdrawal of the paper feed cassette 3. As shown in FIG. 2, the auxiliary roller 6 is formed by integrally molding a cylindrical roller body 11 and a support shaft 12 projecting left and right from the roller body 11 with resin or the like. The auxiliary roller 6 configured as described above has a support shaft 12 rotatably supported by a support body 13 provided in the vicinity of the end portion of the guide rail 5 on the front side of the apparatus. It is located at a height substantially equal to the receiving surface 9 of the rail 5. Therefore, the auxiliary roller 6 abuts against the bottom of the paper feed cassette 3 guided along the guide rail 5 and rotates as the paper feed cassette 3 is inserted and pulled out. As a result, the paper feed cassette 3 is assisted by the auxiliary roller 6 to reduce friction with the guide rail 5 and can be smoothly inserted and pulled out.

  The paper size sensor 7 is for detecting the paper size of the recording paper stored in the paper feed cassette 3. Here, FIG. 3 is a diagram showing the configuration of the paper size sensor 7, FIG. 3A is a schematic perspective view seen from the front side, and FIG. 3B is a schematic perspective view seen from the back side. As shown in FIG. 3A, the paper size sensor 7 includes a sensor main body 14 in which a resin or the like is molded into a box shape, a sensor filler 15 that can be projected and retracted from the surface of the sensor main body 14, and the sensor main body 14. And a projecting portion 16 that projects from one side surface to the side. Here, four substantially rectangular filler protrusions 17 are formed on the surface of the sensor main body 14 in a vertical line. The four sensor fillers 15 are plate-like members made of resin or the like, and are provided so as to be able to appear and disappear from the inside of the sensor main body 14 through the filler protrusions 17. Each sensor filler 15 is urged in a direction protruding from the sensor main body 14 by an unillustrated elastic member or the like, and is in a state of protruding from the sensor main body 14 when no external force is applied. According to the paper size sensor 7 configured as described above, a combination pattern of protrusions or immersions of the four sensor fillers 15 corresponding to various standard sizes of the recording paper is stored in advance. Each immersion state is detected and compared with a previously stored pattern, whereby the paper size of the recording paper stored in the paper feed cassette 3 is determined.

  Further, as shown in FIG. 3B, two positioning bosses 18 project from the back surface of the sensor body 14. The positioning boss 18 is for positioning the paper size sensor 7 with respect to the apparatus main body 2. Each positioning boss 18 has substantially the same shape of a truncated cone, and is provided at predetermined intervals in the vertical direction.

  The sheet size sensor 7 configured as described above is attached to the apparatus main body 2 so as to be movable up and down. Here, FIG. 4 is a schematic front view showing a state in which the blindfold cover 8 is removed from the state shown in FIG. FIG. 5 is a schematic front view showing a state in which the paper size sensor 7 is removed from the state shown in FIG. As shown in FIG. 5, a frame member 19 made of metal or the like is provided above the auxiliary roller 6 inside the apparatus main body 2. Two frame members 19 are provided at predetermined intervals in the vertical direction. The long hole 20 is formed. Here, the two long holes 20 have the same shape, and the width dimension thereof is substantially equal to the outer diameter of the positioning boss 18 of the paper size sensor 7, and the length dimension of the two long holes 20 rises in the paper feed cassette 3 described later. It is formed slightly larger than the width. The distance from the lowermost position of the upper elongated hole 20 to the lowermost position of the lower elongated hole 20 is equal to the distance between the centers of the two positioning bosses 18 of the paper size sensor 7.

  Here, FIG. 6 is an explanatory diagram for explaining the attachment of the paper size sensor 7 to the apparatus main body 2 and the vertical movement of the paper size sensor 7, and the periphery of the frame member 19 is viewed from the back side of the apparatus. Indicates the state. As shown in FIGS. 6A and 6B, the paper size sensor 7 is attached to the surface side of the frame member 19 by inserting the two positioning bosses 18 into the two long holes 20, respectively. Can be moved up and down from the state where each is positioned at the lowest position of each slot 20 to the state where each positioning boss 18 is positioned at the top position of each slot 20. Furthermore, as shown in FIG. 6, a sponge (pressing member) 21 is interposed in a compressed state between the upper surface of the sensor main body 14 and the inner surface of the blind cover 8. As a result, the sheet size sensor 7 has its positioning bosses 18 positioned at the end of the long holes 20 as shown in FIG. 6A in a state in which no external force is applied due to its own weight and further downward pressure from the sponge 21. It is positioned in a state where it is located at the lower position.

  The material and shape of the sensor body 14 constituting the paper size sensor 7 and the material, shape and number of sensor fillers 15 are not limited to the present embodiment, and can be appropriately changed in design. Further, as means for pressing the sensor main body 14 downward, elastic members such as various springs and rubber may be used instead of the sponge 21 of the present embodiment. Furthermore, the sponge 21 of this embodiment is not an essential constituent element of the present invention, and the paper size sensor 7 is positioned in a state where each positioning boss 18 is positioned at the lowest position of each long hole 20 only by its own weight. You can also However, when the sensor body 14 is pressed downward with the sponge 21 as in the present embodiment, the sheet size sensor 7 that has moved to the state shown in FIG. There is an advantage of surely returning to the state shown in FIG.

  The blind cover 8 is used to hide various members such as the paper size sensor 7 from the outside of the apparatus. As shown in FIG. 2, the blind cover 8 is manufactured by resin molding or the like in accordance with the internal shape of the apparatus main body 2, and passes through the filler for avoiding interference with the sensor filler 15 of the paper size sensor 7. A window 22 is formed. As shown in FIG. 2, the blind cover 8 is attached so as to cover various members such as the paper size sensor 7 so that the filler passage window 22 is aligned with the position of the sensor filler 15. At this time, the protruding portion 16 of the paper size sensor 7 shown in FIG. 3 is exposed without being covered by the blindfold cover 8.

  On the other hand, FIG. 7 is a schematic perspective view showing the configuration of the paper feed cassette 3. As shown in the figure, the paper feed cassette 3 includes a cassette main body 24 for storing recording paper, a front cover 25 provided on the front side of the cassette main body 24, and a cassette main body 24 side of the front cover 25. A size dial (filler operation unit) 26 provided on the surface is provided.

  Here, as shown in FIG. 7, the cassette body 24 is formed with an upwardly convex arcuate positioning groove 27 at a position on the front cover 25 side on the bottom surface thereof. The positioning groove 27 is used to position the paper feed cassette 3 inserted into the apparatus main body 2 so that it cannot move. The concave groove 27 for positioning is formed in an arc shape that fits into the auxiliary roller 6 shown in FIG. According to such a configuration, when the paper feed cassette 3 is inserted into the apparatus main body 2 with its bottom face in contact with the guide rail 5, the image forming apparatus shown in FIG. Similar to the 80 sheet cassette 81, after the edge 28 of the positioning groove 27 abuts the auxiliary roller 6, the edge 28 moves to the top along the peripheral surface of the auxiliary roller 6. In the meantime, the paper feed cassette 3 gradually rises. When the paper feeding cassette 3 is further inserted from there, the paper feeding cassette 3 is gradually moved as the edge 28 of the positioning groove 27 moves downward along the peripheral surface of the auxiliary roller 6. Sink into. Then, when the positioning concave groove 27 is fitted into the auxiliary roller 6, the paper feed cassette 3 is positioned at the insertion position.

  Further, as shown in FIG. 7, a flat sensor contact portion 29 is provided on the side of the cassette body 24 on the size dial 26 side so as to protrude sideways. The sensor abutting portion 29 inserts the paper feed cassette 3 into the apparatus main body 2 and, as shown in FIG. 6A, the protruding portion of the paper size sensor 7 when the bottom surface of the cassette main body 24 is in contact with the guide rail 5. 16 abuts from below. Note that the shape of the sensor contact portion 29 can be appropriately changed in accordance with the shape and installation position of the paper size sensor 7.

  The size dial 26 is for causing the image forming apparatus 1 to recognize the paper size of the recording paper stored in the paper feed cassette 3 by operating the sensor filler 15 of the paper size sensor 7. As shown in FIG. 7, the size dial 26 is a cylindrical member made of resin or the like, and a plurality of scales 30 for displaying various standard sizes of recording paper are attached to the peripheral surface thereof at predetermined intervals. In addition, a filler receiving groove 31 that can receive the sensor filler 15 of the paper size sensor 7 is formed at a predetermined location on one end face thereof. The size dial 26 configured as described above is rotatably supported on the cassette body 24 side of the front cover 25 as shown in FIG.

  When using the size dial 26, the user pulls out the paper feed cassette 3 from the apparatus main body 2 and stores recording paper of a desired paper size, and then the scale 30 fits the paper size of the recording paper stored. Turn dial 26 to adjust. When the paper feed cassette 3 is inserted into the apparatus main body 2, the size dial 26 is placed at a position opposite to the sensor filler 15, like the uppermost sensor filler 15 shown in FIG. 8A and the third sensor filler 15 from the top. When there is the filler receiving groove 31, the sensor filler 15 biased in the protruding direction as described above is stored in the filler receiving groove 31 in a state of protruding from the sensor main body 14 as shown in FIG. 8B. On the other hand, when there is no filler receiving groove 31 of the size dial 26 at the opposite position of the sensor filler 15 as in the second sensor filler 15 from the top and the fourth sensor filler 15 from the top shown in FIG. When pressed, the sensor filler 15 is immersed in the sensor body 14 against the urging force. The paper size of the recording paper stored in the paper feed cassette 3 is determined by detecting the protruding or immersing state of the four sensor fillers 15.

  The operational effects of the image forming apparatus 1 configured as described above will be described. FIG. 9 is a schematic diagram for explaining the function and effect of the image forming apparatus 1. As described above, when the paper feed cassette 3 is inserted into the apparatus main body 2, the sensor abutting portion of the paper feed cassette 3 as shown in FIG. 6A in a state where the bottom surface of the cassette main body 24 is in contact with the guide rail 5. 29 abuts against the protrusion 16 of the paper size sensor 7 from below. In this state, when the paper feed cassette 3 is inserted into the apparatus back side along the guide rail 5, the edge 28 of the positioning groove 27 contacts the auxiliary roller 6 as described above. It gradually floats until it reaches the top along its circumference after contact. The sheet size sensor 7 receives an upward pressing force from the sensor contact portion 29 of the sheet feeding cassette 3 due to the lifting of the sheet feeding cassette 3. Here, the paper size sensor 7 is attached to the frame member 19 of the apparatus main body 2 so as to be movable up and down as described above. Accordingly, when the paper size sensor 7 receives the upward pressing force from the paper feed cassette 3, each positioning boss 18 moves upward from the lowest position of each elongated hole 20 against the downward pressing force received from the sponge 21. As a result, it floats following the paper feed cassette 3. Then, when the edge 28 of the positioning groove 27 shown in FIG. 7 reaches the top of the auxiliary roller 6 and the lifting of the paper feed cassette 3 stops, the lifting of the paper size sensor 7 also stops. At this time, in the paper size sensor 7, as shown in FIG. 6B, each positioning boss 18 reaches the uppermost position of each long hole 20.

  Thereafter, when the sheet feeding cassette 3 is further inserted into the back of the apparatus, as the edge portion 28 of the positioning groove 27 shown in FIG. 7 moves downward along the peripheral surface of the auxiliary roller 6, The paper feed cassette 3 gradually sinks. Due to the sinking of the paper feed cassette 3, the paper size sensor 7 is not subjected to an upward pressing force from the paper feeding cassette 3. Therefore, the paper size sensor 7 that receives the downward pressing force from the sponge 21 is provided with each positioning boss. As 18 moves downward along the long holes 20, it sinks following the paper feed cassette 3. Then, when the sinking of the paper feed cassette 3 is stopped by fitting the positioning concave groove 27 to the auxiliary roller 6, the sinking of the paper size sensor 7 is also stopped. At this time, in the paper size sensor 7, as shown in FIG. 6A, each positioning boss 18 has reached the lowest position of each slot 20.

  Here, before the paper feed cassette 3 inserted into the apparatus main body 2 starts to float, as shown in FIG. 8A, the size dial 26 has the second sensor filler 15 from the top of the paper size sensor 7 and the top. Filler receiving grooves 31 are respectively formed at positions facing the fourth sensor filler 15, and no filler receiving grooves 31 are formed at positions facing the top sensor filler 15 and the third sensor filler 15 from the top. Shall.

  In this case, when the paper feed cassette 3 starts to float, as shown in FIG. 9A, the size dial 26 floats by a predetermined distance while approaching the paper size sensor 7, while the paper size sensor 7 also feeds the paper feed cassette 3. Is lifted by the same distance as the size dial 26. Accordingly, in the size dial 26 after being lifted, the filler receiving groove 31 is still formed at a location facing the second sensor filler 15 from the top and the fourth sensor filler 15 from the top, and the size filler 26 from the top. The filler receiving groove 31 is not formed at a location facing the third sensor filler 15 from the first. When the size dial 26 approaches the paper size sensor 7, the uppermost sensor filler 15 and the third sensor filler 15 from the top are pressed by the size dial 26, and a part of them is immersed in the sensor body 14. Part of the second sensor filler 15 from the top and the fourth sensor filler 15 from the top are accommodated in the filler accommodation groove 31. In FIG. 9A, the size dial 26 before the lifting and the paper size sensor 7 are indicated by a one-dot chain line, and the illustration of the sensor fillers 15 is omitted for the paper size sensor 7 before the lifting.

  Thereafter, when the paper feed cassette 3 starts to sink, as shown in FIG. 9B, the size dial 26 sinks by a predetermined distance while further approaching the paper size sensor 7, while the paper size sensor 7 also has its own weight. The pressing force from the sponge 21 sinks the same distance as the size dial 26. Therefore, in the size dial 26 after the sinking, the filler receiving groove 31 is still formed at a position facing the second sensor filler 15 from the top and the fourth sensor filler 15 from the top, and the uppermost sensor filler 15 and The filler receiving groove 31 is not formed at a location facing the third sensor filler 15 from the top. As the size dial 26 further approaches the paper size sensor 7, the uppermost sensor filler 15 and the third sensor filler 15 from the top are pressed by the size dial 26 and immerse into the sensor body 14 deeper than FIG. 9A. The second sensor filler 15 from the top and the fourth sensor filler 15 from the top are accommodated in the filler accommodation groove 31 deeper than FIG. 9A. In FIG. 9B, the size dial 26 before sinking and the paper size sensor 7 are indicated by alternate long and short dash lines, and the illustration of each sensor filler 15 is omitted for the paper size sensor 7 before sinking.

  After that, when the paper feed cassette 3 is positioned and its sinking is stopped, the top sensor filler 15 and the third sensor filler 15 from the top are in an immersive state by the paper size sensor 7. It is detected that the sensor filler 15 and the fourth sensor filler 15 from the top are in a protruding state. Based on the detection result, the paper size of the recording paper stored in the paper feed cassette 3 is determined.

  Thus, even if the paper feed cassette 3 moves up and down before being positioned at the insertion position, the paper size sensor 7 also moves up and down following this, so the vertical direction between the size dial 26 and the paper size sensor 7 The positional relationship to is not changed. Therefore, as described in the image forming apparatus 70 according to the conventional example, the operation of each sensor filler 15 by the size dial 26 is not distorted, and the paper size of the recording paper is not erroneously detected. Thereby, the paper size of the recording paper stored in the paper feed cassette 3 can be accurately determined without being affected by the vertical movement before positioning of the paper feed cassette 3.

  The image forming apparatus according to the present invention is not limited to a copy facsimile multifunction peripheral, and may be configured as, for example, a copy-only machine having only a copy function or a facsimile-only machine having only a facsimile communication function.

1 is a schematic perspective view showing an appearance of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a view showing a lower front portion 4 of the apparatus main body 2 constituting the image forming apparatus 1 and shows a state in which one of the paper feed cassettes 3 is pulled out. 3A and 3B are diagrams illustrating a configuration of a paper size sensor 7, in which FIG. 3A is a schematic perspective view seen from the front surface side, and FIG. 3B is a schematic perspective view seen from the back surface side. The schematic front view which shows the state which removed the blindfold cover 8 from the state shown in FIG. FIG. 5 is a schematic front view illustrating a state in which the paper size sensor 7 is removed from the state illustrated in FIG. 4. FIG. 7 is an explanatory diagram for explaining the attachment of the paper size sensor 7 to the apparatus main body 2 and the vertical movement of the paper size sensor 7, and shows a state in which the periphery of the frame member 19 is viewed from the back side of the apparatus. FIG. 3 is a schematic perspective view showing a configuration of a paper feed cassette 3. The schematic diagram for demonstrating operation of the sensor filler 15 by the size dial 26. FIG. FIG. 3 is a schematic diagram for explaining the function and effect of the image forming apparatus 1. The schematic perspective view which showed the structure of the lower part of the front especially about the image forming apparatus 70 using the size dial which concerns on a prior art example. FIG. 6 is a schematic diagram for explaining the positional relationship between a paper size sensor 75 and a size dial 74 when the paper feed cassette 72 is moved up and down. FIG. 3 is a schematic longitudinal sectional view showing a structure around a sheet feeding cassette 81, in particular, for an image forming apparatus 80 according to a conventional example provided with auxiliary rollers and positioning concave grooves.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 3 Paper feed cassette 6 Auxiliary roller 7 Paper size sensor 14 Sensor main body 15 Sensor filler 18 Positioning boss 20 Elongated hole 21 Sponge (pressing member)
26 Size dial (filler operation part)
27 Groove for positioning 29 Sensor contact part

Claims (3)

A paper feed cassette that is provided so as to be able to be inserted into and withdrawn from an apparatus main body that accommodates the image forming unit, and that stores recording paper supplied to the image forming unit;
An auxiliary roller that is rotatably provided inside the apparatus main body and abuts against the bottom of the paper feed cassette to assist the insertion and withdrawal of the paper feed cassette;
A positioning groove formed in an arc shape at the bottom of the paper feed cassette, and for positioning the paper feed cassette at an insertion position by fitting with the auxiliary roller;
A sensor filler is provided so as to be able to move in and out from a sensor main body provided in the apparatus main body so as to be movable up and down, and by detecting the protrusion or immersion state of the sensor filler, the recording paper stored in the paper feed cassette A paper size sensor for determining the paper size;
A sensor abutting portion that protrudes from the sheet feeding cassette and abuts against the sheet size sensor from below;
A filler operation unit that is provided on the sheet feeding cassette so as to face the apparatus main body, and that operates the sensor filler to move in and out as the sheet feeding cassette is inserted and pulled out;
An image forming apparatus comprising:   A positioning boss protrudes from the sensor body of the paper size sensor, and a long hole is formed in the apparatus main body. The paper size sensor is inserted into the apparatus main body by inserting the positioning boss into the long hole. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided so as to be vertically movable.   The image forming apparatus according to claim 2, further comprising a pressing member that presses a sensor body of the paper size sensor downward.

Images