Media cassette, media feed device and image formation apparatus

Abstract

To improve the durability of a media cassette to be mounted on an image formation apparatus.SOLUTION: The present invention relates to a media cassette to be mounted on an image formation apparatus. The media cassette is detachable relative to an image formation apparatus body, and can be mounted with media. The media cassette comprises: a media mounting stand which can be mounted with media; and a regulation member which regulates the position of an end on the mounting side in the detachable direction of the media cassette relative to the media on the media mounting stand. The regulation member includes a regulation member side engagement part which is engageable with the media mounting stand, and the media mounting stand includes a body side engagement part provided with an engager which is engaged with the regulation member side engagement part and can position the regulation member. The engager is provided to extend in a direction orthogonal to the detachable direction and has an arch shape which curves to protrude toward the detachable side in the detachable direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus having a media cassette. [Background technology]

[0002] Conventionally, image forming devices such as electrophotographic printers, facsimile machines, and copiers are provided with a media cassette that can hold a plurality of media and is detachably attached to the image forming device main body. In conventional image forming devices, the media placed in the media cassette are fed one sheet at a time by a media feeding means, transported to the image forming means, and then an image is formed on the media.

[0003] Conventional media cassettes for image forming devices are provided with a regulating member that regulates the position of a medium placed therein. Conventionally, media cassettes have been known in which the media cassette body has a second engagement portion that engages with a first engagement portion provided on the regulating member to position the regulating member (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-250816 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional image forming devices, when a media cassette is inserted or removed with media loaded, a load is placed on the second engagement portion on the media tray main body from the regulating member, so there is a need to further improve the durability of the second engagement portion provided on the media cassette main body for media cassettes mounted in conventional image forming devices.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a media cassette with improved durability. [Means for solving the problem]

[0007] The first invention is a media cassette that is detachably attached to an image forming apparatus main body and can have media placed thereon, the media cassette having a media placement stand on which the media can be placed, and a regulating member that regulates the position of the mounting side end of the media cassette on the media placement stand in the attachment / detachment direction relative to the media, the regulating member having a regulating member side engaging portion that can engage with the media placement stand, the media placement stand having a main body side engaging portion equipped with an engaging element that can engage with the regulating member side engaging portion to position the regulating member, the engaging element being provided extending in a direction perpendicular to the attachment / detachment direction and having an arch shape that curves so as to protrude toward the detachment side in the attachment / detachment direction.

[0008] A medium supplying device according to a second aspect of the present invention is characterized by having the medium cassette according to the first aspect of the present invention.

[0009] The image forming apparatus according to the third aspect of the present invention is characterized by having the medium cassette according to the first aspect of the present invention. Effect of the Invention

[0010] According to the present invention, it is possible to improve the durability of a medium cassette installed in an image forming apparatus. [Brief description of the drawings]

[0011] [Figure 1] 4 is a plan view of a portion of a paper cassette (paper placement table) according to the embodiment where a tail guide is attached. FIG. [Diagram 2] 1 is a perspective view of a printer according to an embodiment. [Diagram 3] 1 is a schematic side cross-sectional view showing an internal configuration of a printer according to an embodiment. [Figure 4] FIG. 2 is a perspective view of a paper cassette according to the embodiment. [Diagram 5] FIG. 4 is a bottom view of the tail guide body according to the embodiment. [Figure 6] FIG. 2 is a perspective view of a lock lever according to the embodiment. [Figure 7] 11 is a perspective view showing a state in which a spring is attached to a spring receiving portion of the lock lever according to the embodiment. FIG. [Figure 8] FIG. 4 is an enlarged perspective view of a portion of the rack unit according to the embodiment. [Figure 9] FIG. 4 is a bottom view of the lock lever according to the embodiment. [Figure 10] 2 is an end view taken along line AA' in FIG. 1. [Figure 11] 11 is an enlarged view of an engagement portion between a lock lever and a rack portion in the end view of FIG. 10. FIG. [Figure 12] 4 is an enlarged view of a portion of a cross section (cross section in the attachment / detachment direction) of an engagement element that constitutes a rack portion according to the embodiment. FIG. [Figure 13] 13 is a top view of one of the engagement elements constituting the rack portion according to the embodiment and rib portions at both ends of the engagement element. FIG. [Figure 14] 6 is a conceptual diagram showing stresses generated in an engagement element that constitutes the rack portion according to the embodiment. FIG. [Figure 15] 13A and 13B are conceptual diagrams showing a method for designing the arch shape of an engagement element according to the embodiment. [Figure 16] 13 is a diagram showing parameters that change with the radius of an arch shape that constitutes an engagement element according to the embodiment. FIG. [Figure 17] 13 is a diagram showing the values ​​of each parameter when the radius of the arch shape constituting the engaging element according to the embodiment is changed. FIG. [Figure 18] FIG. 13 is a diagram showing a model of an engagement element used in a simulation performed to confirm the effects of the embodiment. [Figure 19] 11 is a graph showing the relationship between the tangent angle and the maximum stress in the engagement element, which is derived from the results of a simulation performed to confirm the effects of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (A) Main embodiment Hereinafter, an embodiment of a medium cassette, a medium supplying device, and an image forming device according to the present invention will be described in detail with reference to the drawings. In this embodiment, an example in which the image forming device of the present invention is applied to a printer will be described. Also, in this embodiment, an example in which the medium supplying device and the image forming device of the present invention are mounted on a printer will be described.

[0013] (A-1) Configuration of the embodiment FIG. 2 is a perspective view of the printer 1 according to this embodiment.

[0014] FIG. 3 is a schematic cross-sectional side view showing the internal configuration of the printer 1 according to this embodiment.

[0015] The printer 1 as an image forming device forms an image on a medium, namely, paper M, by electrophotography based on data etc. supplied from an external source. The printer 1 has at least an image forming section 10, a paper supply unit 20 as a medium supply device, a paper transport section 30, a transfer unit 40, a fixing unit 50, a paper discharge unit 60 and a paper stacker 70.

[0016] The paper supply unit 20 has a paper cassette 21 as a medium cassette capable of mounting (stacking) a plurality of sheets of paper M, a cassette housing section 22 that houses the paper cassette 21, and a paper feed section 23 that feeds the sheets of paper M placed in the paper cassette 21. The paper feed section 23 has a pickup roller 231 and a paper feed roller 232, and separates the sheets of paper M stacked (placed) in the paper cassette 21 one by one and feeds them downstream in the paper transport direction (towards the image forming section 10). The sheets of paper M fed from the paper feed section 23 are supplied to the image forming section 10 via the paper transport section 30.

[0017] The cassette housing section 22 is disposed at the bottom of the printer 1, and the paper cassette 21 is structured to be detachable from the printer 1 body (cassette housing section 22). In Fig. 3, an "attachment / detachment direction" which is a direction in which the paper cassette 21 slides when it is attached to or detached from the cassette housing section 22, an "attachment direction" (attachment side) which is a direction in which the paper cassette 21 slides when it is attached (inserted) into the cassette housing section 22, and a "detachment direction" (detachment side) which is a direction in which the paper cassette 21 slides when it is detached (removed) from the cassette housing section 22 are illustrated with arrows. In the following, for ease of explanation and illustration, the "attachment / detachment direction" may be referred to as the "front-rear direction", the attachment direction as the "rear direction", and the detachment direction as the "front direction", as shown in Fig. 3. In the printer 1 of this embodiment, the attachment / detachment direction and the paper transport direction (media transport direction) are configured to coincide (be parallel), but the attachment / detachment direction and the paper transport direction (media transport direction) may also be configured to be different directions (for example, perpendicular to each other).

[0018] The paper transport section 30 includes a first transport roller 31 and a second transport roller 32, and transports the paper M fed from the paper feed section 23 to the image forming section 10.

[0019] Image forming section 10 develops a toner image (developer image) and transfers it onto paper M as a medium, and has four exposure sections 110 (110-1 to 110-4) and four image drum units 120 (120-1 to 120-4).

[0020] Image drum units 120-1 to 120-4 are equipped with toner (developer) of yellow, magenta, cyan, and black, respectively, and are means (developing means) for developing a toner image (developer image) using the toner equipped therein. Note that the number (number of channels) of image drum units 120 / exposure units 110 equipped in image forming section 10 is not limited to the above example.

[0021] Each of image drum units 120-1 to 120-4 has developing device 121, charger 122, and photosensitive unit 123. Exposure units 110-1 to 110-4 are exposure means that expose photosensitive unit 123 of image drum units 120-1 to 120-4 to form an electrostatic latent image, and are configured with a plurality of light-emitting elements arranged in the main scanning direction. Charger 122 is a means for uniformly charging the surface of photosensitive unit 123. Exposure units 110-1 to 110-4 are a means for selectively exposing the uniformly charged surface of photosensitive unit 123 to light to form an electrostatic latent image. Developing device 121 is a means for developing a toner image (developer image) by attaching toner (developer of a corresponding color) to the electrostatic latent image formed on the surface of photosensitive unit 123.

[0022] Each of image drum units 120-1 to 120-4 has a developer 121, a charger 122, and a photosensitive unit 123. Exposure units 110-1 to 110-4 are exposure units that expose photosensitive unit 123 of image drum units 120-1 to 120-4 to form an electrostatic latent image. Charger 122 is a unit that uniformly charges the surface of photosensitive unit 123. Exposure units 110-1 to 110-4 are a unit that selectively exposes the uniformly charged surface of photosensitive unit 123 to form an electrostatic latent image. 121 is a unit that develops a toner image (developer image) by attaching toner (developer of a corresponding color) to the electrostatic latent image formed on the surface of photosensitive unit 123. Exposure unit 110 may be an LED head in which LEDs (Light Emitting Diodes) are arranged as light-emitting elements in the axial direction of image drum unit 120, or may be a laser scanning unit equipped with a laser irradiation unit and a polygon mirror.

[0023] Transfer unit 40 includes four transfer rollers 41 (41-1 to 41-4) and transfer belt 42. Transfer belt 42 is a means for transporting paper M between image drum units 120-1 to 120-4 and transfer devices 41-1 to 41-4. Transfer devices 41-1 to 41-4 are means for transferring toner images developed on the opposing image drum units 120-1 to 120-4 (photosensitive units 123) to paper M transported by transfer belt 42.

[0024] The fixing unit 50 includes a heat roller 510 and a pressure roller 520 that are controlled to have predetermined temperatures, and fixes the image transferred onto the paper M by heat and pressure.

[0025] The paper discharge unit 60 includes a first paper discharge roller 61 and a second paper discharge roller 62, and conveys the paper M on which the image has been fixed for discharge.

[0026] The paper stacker 70 stacks the discharged paper M on top of the printer 1.

[0027] Next, the configuration of the paper cassette 21 will be described.

[0028] FIG. 4 is a perspective view of the paper cassette 21. As shown in FIG.

[0029] In the paper cassette 21, the paper M is placed on the upper surface of a paper placement table 211 serving as a medium placement table.

[0030] In FIG. 4, a direction perpendicular to the attachment / detachment direction (front-rear direction) on the upper surface of paper placement table 211 is shown as a "left-right direction" with an arrow.

[0031] A tail guide 212 is attached to the top surface of the paper loading tray 211 as a regulating member that regulates the position of the rear end of the paper M loaded on the paper loading tray 211. The tail guide 212 is attached so as to be movable in the front-rear direction. This allows multiple types of paper M with different dimensions in the front-rear direction to be loaded on the paper loading tray 211. In addition, a left side guide 213 and a right side guide 214 that regulate the left-right position of the paper M loaded on the paper loading tray 211 are arranged on the top surface of the paper loading tray 211. The left side guide 213 and the right side guide 214 are movable in the left-right direction and can move toward and away from each other. This allows multiple types of paper M with different dimensions in the left-right direction to be loaded on the paper loading tray 211.

[0032] A front cover 210 is provided on the front (front end) of the paper cassette 21, and this front cover 210 forms part of the housing at the lower front of the printer 1. When the paper cassette 21 runs out of paper M, the operator can detach (remove) the paper cassette 21 from the cassette housing section 22 and replenish (place) paper M on the paper placement table 211.

[0033] A pickup roller 231 and a paper feed roller 232 are disposed above the front side of the paper cassette 21 when the paper cassette 21 is inserted inside the printer 1. The pickup roller 231 separates and feeds the paper M one sheet at a time, and the paper feed roller 232 transports (feeds) the separated paper M.

[0034] Next, the details of the configuration in which the tail guide 212 is attached to the paper supply unit 20 will be described.

[0035] As shown in Fig. 4, a rail 216 is provided on the upper surface of the paper placement tray 211 to guide / restrict the tail guide 212 so that it moves only in the attachment / detachment direction. In other words, the rail 216 is arranged to extend in the attachment / detachment direction. The tail guide 212 is slidably attached to this rail 216. Also, on the upper surface of the paper placement tray 211, on the left side of the rail 216, a rack section 215 is arranged that constitutes a mechanism (hereinafter referred to as a "lock mechanism") that fixes (locks) the position of the tail guide 212 so that it is parallel to the rail 216. Furthermore, on the upper surface of the paper placement tray 211, on the right side of the rail 216, a positioning guide 217 is arranged to position the tail guide 212 so that it is parallel to the rail 216.

[0036] Tail guide 212 has a tail guide main body 300 and a lock lever 400 that is detachably attached to tail guide main body 300. Tail guide main body 300 has a guide portion 301 that regulates the position of the rear end of paper M placed on paper placement table 211, and a support portion 302 that supports guide portion 301 below guide portion 301. Support portion 302 is attached to rail 216 so as to be able to slide freely.

[0037] A portion of the lock lever 400 fits under the tail guide main body 300 (support portion 302) and engages with the rack portion 215 to form the lock mechanism described above, which fixes the position of the tail guide 212.

[0038] FIG. 5 is a bottom view of the tail guide body 300. FIG.

[0039] In FIG. 5, the portion recessed from the bottom surface (lower surface) of the tail guide body 300 is shown with hatching (diagonal line pattern), and the hole (through hole) portion is shown colored black.

[0040] 5, a groove 302a is provided on the bottom surface of the tail guide body 300 to engage with the rail 216 and allow the tail guide 212 to slide (in the attachment / detachment direction). The bottom surface of the tail guide body 300 is also provided with an accommodation portion 302b, which is a groove (recess) for accommodating the lock lever 400, and an accommodation portion 302c, which is a groove (recess) for accommodating the positioning guide 217. Furthermore, protruding rotating shafts 302i and 302j are disposed at both ends near the center of the accommodation portion 302b (near the center in the attachment / detachment direction) so as to face each other. The pair of rotating shafts 302i and 302j function as a single rotating shaft for rotatably supporting the lock lever 400.

[0041] FIG. 6 is a perspective view of the lock lever 400. As shown in FIG.

[0042] FIG. 6(a) is a perspective view of the lock lever 400 as viewed obliquely from above, and FIG. 6(b) is a perspective view of the lock lever 400 as viewed obliquely from below.

[0043] As shown in FIG. 6, the lock lever 400 has a fixed portion 402 that contacts and engages with the rack portion 215 of the paper loading platform 211 on the underside of the tail guide main body 300 (support portion 302), and an operation portion 401 for receiving operation from the user (e.g., operation of being pressed by a finger).

[0044] As shown in Fig. 4, a hole 302h is provided on the bottom surface of the tail guide main body 300, into which the operating portion 401 of the lock lever 400 can be inserted from below. When the lock lever 400 is inserted into the tail guide main body 300 (hole 302h), the operating portion 401 becomes one with the guide portion 301, and further the fixing portion 402 is accommodated in the accommodating portion 302c on the lower side of the tail guide main body 300 and becomes one with the support portion 302. As described above, the lock lever 400 is attached so as to be one with the tail guide main body 300. In addition, as shown in Fig. 6, an engagement portion 405 is provided on the front end portion of the lower surface of the support portion 302 as a regulating member side engagement portion for engaging with the rack portion 215.

[0045] 6, the fixed part 402 is provided at both ends (both ends in the left-right direction) near the center in the attachment / detachment direction with a pair of bearing parts 403, 404 that engage with the rotating shafts 302i, 302j on the tail guide main body 300 side. In other words, when the lock lever 400 is attached to the tail guide main body 300 (when the rotating shafts 302i, 302j are engaged with the bearing parts 403, 404), it becomes freely rotatable about the rotating shafts 302i, 302j as the rotation axes.

[0046] 6, substantially cylindrical spring receivers 407, 408 are provided on the upper surface of fixed portion 402 at a portion (front end portion) corresponding to engagement portion 405. Spring receivers 407, 408 are housed in recesses 409, 410 formed on the upper surface of support portion 302, respectively.

[0047] FIG. 7 is a perspective view showing a state in which springs 411 and 412 are attached to spring receiving portions 407 and 408 of the lock lever 400, respectively.

[0048] In Fig. 6, in order to clarify the structure of the lock lever 400 main body, the springs 411 and 412 are removed, but in reality, as shown in Fig. 7, the lock lever 400 is attached to the tail guide main body 300 with the springs 411 and 412 attached thereto. Then, as shown in Fig. 5, substantially cylindrical spring receiving portions 302f and 302g that engage with the springs 411 and 412 are provided on the lower surface of the tail guide main body 300 at positions facing the spring receiving portions 407 and 408 of the lock lever 400. The spring receiving portions 302f and 302g are accommodated in recesses 302d and 302e formed on the lower surface of the tail guide main body 300 (inside the accommodation portion 302b).

[0049] When the lock lever 400 is attached to the tail guide body 300, the springs 411 and 412 are sandwiched between the upper surface of the lock lever 400 and the lower surface of the tail guide body 300. That is, the front end portion (the engagement portion 405 provided at the front end portion of the fixed portion 402) of the lock lever 400 attached to the tail guide body 300 is pressed against the lower rack portion 215 by the elastic force of the springs 411 and 412. When the front end portion (the engagement portion 405 on the lower surface) of the lock lever 400 is pressed against the rack portion 215, it engages with the rack portion 215 and the position (position in the attachment / detachment direction) is fixed. Also, as described above, the lock lever 400 rotates around the bearing portions 403 and 404 as the rotation axis, so that when a rearward stress is applied to the operation portion 401 of the lock lever 400, the front end portion of the fixed portion 402 moves upward and disengages from the rack portion 215, and movement in the attachment / detachment direction (movement along the rail 216) becomes possible. In other words, when the operating portion 401 of the lock lever 400 is operated by the user's finger or the like (for example, when the user's finger pinches the operating portion 401 together with the guide portion 301 of the tail guide main body 300 and pushes the operating portion 401 backward), the locking mechanism is released and the tail guide 212 becomes movable in the attachment / detachment direction, and when the operating portion 401 is released from the operation, the locking mechanism functions to fix the position (position in the attachment / detachment direction).

[0050] Next, the structure in which the rack portion 215 and the engaging portion 405 of the lock lever 400 engage with each other will be described in detail.

[0051] FIG. 8 is an enlarged perspective view of a portion of the rack portion 215. As shown in FIG.

[0052] As shown in FIG. 8, the rack section 215 has a structure in which tooth-shaped (blade-shaped; plate-shaped) engaging members 501 are arranged (standing) in the attachment / detachment direction. That is, in the rack section 215, a plurality of engaging members 501 are arranged as main body side engaging members. As shown in FIG. 8, each engaging member 501 is arranged so as to extend in the left-right direction. Note that the number of engaging members 501 arranged in the rack section 215 is not limited. Also, as shown in FIG. 8, rib members 502, 503 are arranged on both ends (both ends in the left-right direction) of each engaging member 501 as supporting members that support each engaging member 501 along the attachment / detachment direction. Note that each engaging member and the rib members 502, 503 are molded as one piece.

[0053] FIG. 9 is a bottom view of the lock lever 400. FIG.

[0054] 9, in the engagement portion 405 arranged on the bottom surface of the lock lever 400 (fixed portion 402), an engagement element 413 having a shape similar to that of the engagement element 501 of the rack portion 215 is provided upright along the attachment / detachment direction. Note that no rib portion is provided in the engagement portion 405 of the lock lever 400 (fixed portion 402). Also, the number of engagement portions 405 arranged on the lock lever 400 (fixed portion 402) is not limited, and may be one.

[0055] FIG. 1 is a plan view (viewed from above) of a portion of paper cassette 21 (paper placement table 211) where tail guide 212 is attached.

[0056] For convenience of illustration, FIG. 1 shows only the tail guide 212 and its peripheral elements (rack portion 215, rail 216, and positioning guide 217), and omits the illustration of other elements.

[0057] FIG. 10 is an end view taken along line AA' in FIG.

[0058] In FIG. 10, for the sake of clarity, only the spring 411 and the spring receiving portion 407 are shown in cross-sectional view.

[0059] FIG. 11 is an enlarged end view of the portion where the lock lever 400 (engagement portion 405) and the rack portion 215 (engagement element 501) engage with each other (hereinafter referred to as the "engagement portion") in the end view of FIG.

[0060] As shown in FIG. 11, the engagement pieces 413 of the lock lever 400 (engagement portion 405 ) are inserted into the gaps between the engagement pieces 501 of the rack portion 215 , whereby the lock lever 400 engages with the rack portion 215 .

[0061] Next, the shape of each of the engagement pieces 501 that constitute the rack portion 215 will be described.

[0062] FIG. 12 is an enlarged view of a portion of a cross section (cross section in the attachment / detachment direction) of an engagement piece 501 that constitutes the rack portion 215. As shown in FIG.

[0063] 12, in which the shapes of the engaging elements 501 and the intervals between the engaging elements 501 are all the same, three engaging elements 501-1 to 501-3 are arranged in order from the rear side. As shown in FIG. 12, each engaging element 501 is formed with a rear surface 501a as a first surface and a front surface 501b as a second surface.

[0064] As shown in FIG. 12, in each of the engaging elements 501, the rear surface 501a is inclined forward, and the front surface 501b is vertical (not inclined). In FIG. 12, the position of the front end portion of the engaging element 501-1 (position in the attachment / detachment direction) is P1, the position of the rear end portion of the engaging element 501-2 is P2, the position of the front end portion of the rear surface 501a of the engaging element 501-2 is P3, and the position of the front end portion of the engaging element 501-2 is P4. In FIG. 12, the dimension between the positions P2 and P4 (the dimension of the lower end of each engaging element 501) is L1, the dimension between the positions P3 and P4 (the dimension of the upper end of each engaging element 501) is L2, the dimension between the positions P1 and P2 is L3, and the dimension between the positions P1 and P4 (the interval at which each engaging element 501 is arranged (hereinafter also referred to as the "pitch width") is L4. In FIG. 12, the height of each engaging element 501 is L5.

[0065] Here, L1 = 0.6 mm, L2 = 0.3 mm, and L3 = 0.4 mm at least at the center (center in the left-right direction) of each engaging element 501. This results in a pitch width of L4 = 1.0 mm at least at the center (center in the left-right direction) of each engaging element 501. Also, here, L5 = 1.0 mm.

[0066] The engaging elements 413 constituting the engaging portion 405 on the lock lever 400 side are also assumed to have the same shape and be arranged at the same pitch as the engaging elements 501. Therefore, a detailed description of the shape of the engaging elements 413 on the lock lever 400 side will be omitted here.

[0067] FIG. 13 is a diagram of one engagement piece 501 constituting the rack portion 215 and the rib portions 502, 503 on both ends thereof, as viewed from above.

[0068] In FIG. 13, the lines defining the upper end portion of the engaging piece 501 are omitted.

[0069] As shown in FIG. 13, the engaging piece 501 is not parallel to the left-right direction but has a curved arch shape that protrudes forward.

[0070] FIG. 14 is an image diagram showing stress generated in the engaging element 501 constituting the rack portion 215 shown in FIG.

[0071] FIG. 14(a) shows the case where the engaging element 501 is arch-shaped, and FIG. 14(b) is a diagram showing a hypothetical case where the engaging element 501 is not arch-shaped (i.e., is not curved but has a straight line in the left-right direction).

[0072] When the paper cassette 21 is attached or detached (inserted) in the image forming unit 10 (cassette housing unit 22), a rearward stress (load) is applied to the tail guide 212. Since the tail guide 212 is fixed at the engagement portion between the lock lever 400 (engagement portion 405) and the rack portion 215 (engagement piece 501), the stress applied to the tail guide 212 is applied to the engagement portion.

[0073] That is, as shown in Fig. 14, when the paper cassette 21 is attached or detached (inserted or removed), a rearward stress is applied to the engaging member 501 of the rack portion 215. In Fig. 14(a), the engaging member 501 has an arch shape that curves so as to protrude forward, so that part of the rearward tensile force applied to the engaging member 501 is converted into a compressive force in the left-right direction from the center portion (the center portion in the left-right direction) of the engaging member 501 and is received by the rib portions 502 and 503 at both ends, thereby reducing the rearward tensile force accordingly.

[0074] On the other hand, as shown in Fig. 14(b), if the shape of the engaging element 501 were linear (not arch-shaped), the tensile force would not be converted into a compressive force, and most of the rearward stress applied to the engaging element 501 would become a rearward tensile force. In other words, in the engaging element 501 of this embodiment, the arch-shaped engaging element can reduce the rearward tensile force. Since the destruction (breakage) of the engaging element 501 is caused by this rearward tensile force becoming a "shear stress," the durability of the engaging element 501 is improved by forming the engaging element 501 into an arch-shaped engaging element.

[0075] The durability of the rack section 215 also changes depending on the material used to mold the lock lever 400 and the rack section 215 that engage with each other. Here, the rack section 215 forms a part of the paper placement table 211 and is a structure that is integrally formed with the paper placement table 211. The material used for the lock lever 400 and the paper placement table 211 (including the rack section 215) is not limited, and various resin materials can be used, for example. In this embodiment, the lock lever 400 is described as using a POM material (polyacetal material), and the rack section 215 (paper placement table 211) is described as using a PS material (polystyrene material). In general, parts made of resin materials tend to be expensive (material cost and manufacturing cost) when a highly durable material is used. Therefore, in this embodiment, the relatively durable and costly POM material is used for small-sized parts, but the relatively durable and cost-effective PS material is used for the large-sized paper placement table 211 (including the rack section 215). In other words, in this embodiment, the durability of the rack portion 215 is lower than that of the lock lever 400, but by making the shape of the engaging member 501 arch-shaped as described above, the durability of the rack portion 215 can be improved (at the same cost) without changing the material.

[0076] Next, a method for designing the arch shape of the engaging element 501 will be described.

[0077] FIG. 15 is an image diagram showing a method for designing the arch shape of the engaging element 501. As shown in FIG.

[0078] Here, a case will be considered in which the rear end portion (rear surface 501a) and the front end portion (front surface 501b) of the engaging element 501 are designed to have arc shapes.

[0079] Fig. 15(a) shows a case where the shapes of the rear end portion (rear surface 501a) and front end portion (front surface 501b) of the engaging element 501 are designed as concentric circles with different radii. In Fig. 15(a), the shape of the rear end portion of the engaging element 501 is shaped along an arc of a circle with a radius R1 and a center at position P11. Also, in Fig. 15(a), the shape of the front end portion of the engaging element 501 is shaped along an arc of a circle with a radius R2 and a center at position P11. Here, R2 is the dimension obtained by adding L1 (here, 0.6 mm) to R1.

[0080] Fig. 15(b) shows a case where the shapes of the rear end portion (rear surface 501a) and the front end portion (front surface 501b) of the engaging element 501 are designed by moving circles of the same shape (circles of the same radius) in the attachment / detachment direction (translating forward). In Fig. 15(b), the shape of the rear end portion of the engaging element 501 is shaped along an arc of a circle with a radius R and centered at position P11. Also, in Fig. 15(b), the shape of the front end portion of the engaging element 501 is shaped along an arc of a circle with a radius R and centered at position P12, which is translated forward from position P11 by L1 (here, 0.6 mm).

[0081] 15, the dimension of the engaging element 501 in the attachment / detachment direction (hereinafter referred to as "engagement element thickness") is L10, and the dimension of the engaging element 501 in the left-right direction (hereinafter referred to as "rack width") is "D." Here, D=11 mm.

[0082] In both the design method of Fig. 15(a) (designing method using concentric arcs) and the design method of Fig. 15(b) (designing method by translating arcs of the same shape), the shape of the engaging element 501 is arch-shaped. However, while the distribution of the engaging element thickness of the engaging element 501 is equal in the left-right direction in the design method of Fig. 15(b), the engaging element thickness differs between the center portion (center portion in the left-right direction) and both end portions (near the left and right rib portions 502, 503) in the design method of Fig. 15(a). Specifically, in the design method of Fig. 15(a), the engaging element thickness is greater at both end portions (near the left and right rib portions 502, 503) than at the center portion (center portion in the left-right direction).

[0083] It is preferable that the distribution of the thickness of the engaging element 501 is equal (uniform) in the left-right direction. The reason for this is that when the engaging element 413 constituting the engaging portion 405 on the lock lever 400 side and the engaging element 501 engage (mesh) with each other, the engaging element 413 having the same thickness in the left-right direction can easily engage with the engaging element 501. Therefore, in this embodiment, the following description will be given on the assumption that the arch shape of the engaging element 501 is designed using the design method of Fig. 15(b) (a method of designing by translating an arc of the same shape).

[0084] Next, suitable parameters to be applied to the arch shape of the engaging element 501 will be described.

[0085] 15(b) (a method of designing by translating an arc of the same shape) as described above. In this case, the radius R of the arc applied to the front end portion and the rear end portion of the engaging element 501 is important in determining the arch shape of the engaging element 501.

[0086] FIG. 16 is a diagram showing parameters a, b, and c that change with the radius R of the arch shape that constitutes the engaging element 501. In FIG.

[0087] 16, the shape of the rear end portion (rear surface 501a) of the engaging element 501 is formed by an arc of a circle with a radius R centered at position P21. Also, in Fig. 16, the shape of the front end portion (front surface 501b) of the engaging element 501 is formed by an arc of a circle with a radius R centered at position P22, which is moved forward from position P22 by the above-mentioned L1. Note that, here, as described above, L1 is 0.6 mm, the left-right positions of positions P21 and P22 are the center of the engaging element 501, and the rack width D is 11 mm. 16, the center position of the front end portion of the engaging member 501 (center position in the left-right direction; position of the apex of the arch shape) is shown as P23, the left end position of the front end portion of the engaging member 501 (position where it contacts the rib portion 503) is shown as P24, the line connecting positions P21 and P24 is shown as X1, the position where line X1 intersects with the rear end portion of the engaging member 501 is shown as P25, and the tangent to the arch shape at position P24 (tangent to the arc that constitutes the front end portion of the engaging member 501) is shown as tangent X2. Furthermore, in FIG. 16, the dimension in the attachment / detachment direction between positions P24 and P23 is shown as a [mm], the angle between tangent X2 and the attachment / detachment direction (rib portion 503) is shown as b [degrees], and the dimension between positions P24 and P25 is shown as c [mm]. Here, a is called the "protrusion amount" (protrusion amount of the arch shape), b is called the "tangent angle" (angle between the tangent of the arch shape and the attachment / detachment direction), and c is called the "minimum plate thickness." Note that since the plate thickness of the arch shape of engaging member 501 (the thickness of engaging member 501 when viewed from position P21) is slightly thinner around rib portions 502 and 503, the portions at positions P25 and P24 are the portions of engaging member 501 where the plate thickness is minimum.

[0088] Here, the design limitations regarding the protrusion amount a and the minimum plate thickness c will be considered.

[0089] The protrusion amount a is preferably equal to or greater than the pitch width L4. Here, the pitch width L4 is set to 1.0 mm, and a design restriction is imposed that the protrusion amount a must be equal to or greater than 1.0 mm. The reason for setting the protrusion amount a to equal to or greater than the pitch width L4 (1 mm) is to ensure a predetermined stress reduction rate (approximately 10% or more) when the engaging element 501 is formed in an arch shape.

[0090] Furthermore, as a restriction (manufacturing restriction) when molding paper placement platform 211 including rack section 215, minimum plate thickness c must be a predetermined value or more. Generally, when molding a resin material, it is processed by a process such as die machining, but if the thickness becomes less than a predetermined value, manufacturing becomes extremely difficult (or manufacturing costs become very high). In particular, it tends to be very difficult to mold a resin material into a shape with a thickness of 0.5 mm or less. Therefore, here, a design restriction is imposed that minimum plate thickness c must be 0.5 mm or more.

[0091] In view of the above, it is necessary to consider the optimum range of radius R to set the protrusion amount a to 1.0 mm or more and the minimum plate thickness c to 0.5 mm or more.

[0092] FIG. 17 is a diagram showing the values ​​of the parameters a, b, and c when the radius R of the arch shape constituting the engaging piece 501 is changed.

[0093] 17 shows parameters a, b, and c when radius R is ∞ (infinity), 15.625 mm, 10 mm, and 6 mm. When radius R is ∞ (infinity), the shape of engaging element 501 is not an arch shape but a straight line (the shapes of the front end portion and the rear end portion of engaging element 501 are lines parallel to the left and right).

[0094] As shown in Fig. 17, when the radius R = 15.625 mm, the protrusion amount a is 1.0 mm. Also, as shown in Fig. 17, when the radius R = 10 mm, the minimum plate thickness c = 0.506 mm. Therefore, in order to comply with the above design restrictions, it is clear that the radius R needs to be within the range shown in the following formula (1). 15.625mm≧Radius R≧10.0mm…(1)

[0095] As shown in Fig. 17, when the radius R = 15.625 mm, [protrusion amount a = 1.0 mm, tangent angle b = 69.4 degrees, minimum plate thickness c = 0.563 mm]. Also, as shown in Fig. 17, when the radius R = 10 mm, [protrusion amount a = 1.648 mm, tangent angle b = 56.6 degrees, minimum plate thickness c = 0.506 mm]. From the above, it can be seen that in order to comply with the above design restrictions, the protrusion amount a, tangent angle b, and minimum plate thickness c must be within the ranges of the following formulas (2), (3), and (4), respectively. 1mm≦Protrusion amount a≦1.648mm…(2) 56.6°≦Tangential angle b≦69.4°…(3) 0.506mm≦Minimum plate thickness c≦0.563mm…(4)

[0096] (A-2) Operation of the embodiment Next, the operation of the printer 1 according to this embodiment will be described.

[0097] For example, in the image forming unit 10, when the paper cassette 21 is inserted with a plurality of sheets of paper M placed (stacked) on the paper placement tray 211, a rearward inertial force is applied to the sheets of paper M. The inertial force is transmitted as stress from the sheets of paper M to the rack unit 215 (the engagement piece 501) via the tail guide 212 and the lock lever 400.

[0098] At this time, as shown in FIG. 14(a), in the engaging member 501 of the rack portion 215, stress is applied mainly to the arch-shaped protruding portion (the central portion in the left-right direction), but part of the rearward stress applied to the engaging member 501 is converted into a compressive force in the left-right direction from the central portion (the central portion in the left-right direction) of the engaging member 501, and therefore the tensile force in the rearward direction is reduced by that amount.

[0099] (A-3) Effects of the embodiment According to this embodiment, the following effects can be obtained.

[0100] Each of the engaging members 501 of the rack section 215 has an arch shape that curves so as to protrude forward. As a result, the stress acting on each of the engaging members 501 of the rack section 215 is divided into a tensile force in the rear direction and a compressive force in the left-right direction, as shown in FIG. 14(a). At this time, the engaging member 501 is divided into a large proportion of compressive force and a small proportion of tensile force due to the arch-shaped structure. Therefore, in this embodiment, the tensile force that affects the destruction of the engaging member 501 is small, and as a result, durability can be improved without changing the material or pitch width of the rack section 215 (each engaging member 501). The durability of the rack section 215 (each engaging member 501) can be improved by widening the pitch width, but this would widen the positioning pitch (positioning grid width) of the tail guide 212. If the positioning pitch (positioning grid width) of the tail guide 212 is widened, the gap between the paper M placed on the paper placement table 211 and the tail guide 212 may widen, which is not preferable because it may cause paper feeding problems. However, if the shape of each engaging element 501 of the rack portion 215 is simply made arch-shaped as described above, there is no need to widen the pitch width, and therefore the positioning pitch of the tail guide 212 is not affected.

[0101] In addition, in the rack portion 215 of this embodiment, both left and right ends of each engaging element 501 are supported by the rib portions 502, 503. As a result, in the rack portion 215 of this embodiment, the compressive force generated in each engaging element 501 is received by the rib portions 502, 503, thereby improving durability.

[0102] Here, a description will be given of a simulation (hereinafter, the results of the present simulation) performed by the inventor of the present application to verify the effect (reduction in pulling force) of forming each of the engaging elements 501 into an arch shape.

[0103] In this simulation, the maximum value of stress (hereinafter referred to as "maximum stress") generated when a predetermined stress was applied to the engaging element 501 of each model shown in Figure 18 (each model of Figures 18(a) to 18(d)) was obtained.

[0104] In this simulation, ANSYS (registered trademark) Workbench (static structural force test) was used as the simulation environment. In this simulation, when a stress (rearward stress) of 350 [N] was applied to the engaging element 501 of each model shown in Fig. 18, the distribution of tensile forces acting on each part of the engaging element 501 was confirmed, and the largest value among them was extracted as the maximum stress [MPa]. Note that the above-mentioned 350 [N] is the stress that occurs when 250 sheets of A4 size paper are placed (stacked) on the paper cassette 21 (paper placement table 211) and the paper cassette 21 is attached or detached.

[0105] FIG. 18 is a diagram showing a model of the engaging element 501 used in this simulation.

[0106] 18(a) to 18(d), the maximum stress was calculated for each of a model where the radius R is 5.5 mm (hereinafter referred to as "R5.5"), a model where the radius R is 6 mm (hereinafter referred to as "R6"), a model where the radius R is 10 mm (hereinafter referred to as "R10"), and a model where the shape of the engaging element 501 is a straight line rather than an arch shape (i.e., R = ∞) (hereinafter simply referred to as "straight line"). Note that the tangent angles b of the R5.5 model, R6 model, R10 model, and straight line model are 0 degrees, 23.6 degrees, 56.6 degrees, and 90 degrees, respectively.

[0107] As a result of this simulation, the maximum stress of the R6 model was 66.3 [MPa], the maximum stress of the R10 model was 73.0 [MPa], and the maximum stress of the straight line model was 84.1 [MPa]. Note that this simulation was unable to analyze the maximum stress of the R5.5 model.

[0108] FIG. 19 is a graph showing the relationship between the tangent angle b of the engaging element 501 and the maximum stress, which is derived from the results of this simulation.

[0109] In the graph of FIG. 19, the horizontal axis represents the tangent angle, and the vertical axis represents the maximum stress (maximum value of tensile force).

[0110] From the above simulation results, it was found that the tensile force of each arch-shaped model (R6 model and R10 model) is reduced compared to the straight model. For example, the tensile force of the straight model is 81.1 MPa, while the tensile force of the R10 model is 73.0 MPa, so in this case, the arch shape has the effect of reducing the tensile force by approximately 13.2%.

[0111] (B) Other embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments such as those exemplified below.

[0112] (B-1) In the above embodiment, the paper supply unit 20 (including the cassette housing section 22 and the paper cassette 21) as the medium supply device is integrated with the printer 1, but the paper supply unit 20 may be configured to be separable from the main body of the image forming section 10. Also, the printer 1 may be configured so that one or more independent / separate paper supply units 20 can be added (stacked) below.

[0113] (B-2) In the above embodiment, an example was described in which the arch shape of the rear end portion (rear surface 501a) and the front end portion (front surface 501b) of the engaging element 501 was designed as a perfect circular (precise circular) arc, but if the arch shape is to be formed, it may be designed as an elliptical arc. [Explanation of symbols]

[0114] 1... printer, 10... image forming section, 20... paper supply unit, 21... paper cassette, 22... cassette storage section, 23... paper feed section, 30... paper transport section, 31... first transport roller, 32... second transport roller, 40... transfer unit, 41, 41-1 to 41-4... transfer roller, 42... transfer belt, 50... fixing unit, 60... paper discharge unit, 61... first paper discharge roller, 62... second paper discharge roller, 70... paper stacker, 110, 110-1 to 110-4... exposure section, 120, 120-1 to 120-4... image drum unit, 121... developer, 122... charger, 123... photosensitive section, 210... front cover, 211... paper placement table, 212... tail guide, 213... left side guide, 214... right side guide, 215... rack section, 216... rail, 2 17...positioning guide, 231...pickup roller, 232...paper feed roller, 300...tail guide body, 301...guide portion, 302...support portion, 302a...groove, 302b...accommodating portion, 302c...accommodating portion, 302d...recess, 302e...recess, 302f...spring receiving portion, 302g...spring receiving portion, 302h...hole, 302i...rotating shaft, 302j...rotating shaft, 400...lock lever , 401...operation portion, 402...fixed portion, 403...bearing portion, 404...bearing portion, 405...engagement portion, 407...spring receiving portion, 408...spring receiving portion, 409...recess, 410...recess, 411...spring, 412...spring, 413...engagement element, 501...engagement element, 501a...rear surface, 501b...front surface, 502...rib portion, 503...rib portion, 510...heat roller, 520...pressure roller

Claims

1. A medium cassette that is detachably attached to an image forming apparatus main body and capable of holding a medium therein, a medium placement stage on which the medium can be placed, and a regulating member that regulates the position of an end of the medium on the medium placement stage in a direction in which the medium cassette is attached and detached, the regulating member has a regulating member side engaging portion that is engageable with the medium placement table, the medium placement platform has a main body side engaging portion including an engaging element that can engage with the regulating member side engaging portion to position the regulating member, The engaging piece is provided on the medium placement table so as to extend in a direction perpendicular to the mounting / removal direction, and has an arch shape that is curved so as to protrude toward the removal side in the mounting / removal direction. A media cassette comprising:

2. In the main body side engaging portion, a plurality of the engaging elements are arranged in the attachment / detachment direction, Each of the engaging members has a first surface extending in a direction perpendicular to the mounting direction on the medium mounting table, and a second surface provided on the removal side of the mounting direction from the first surface, and the shape of the second surface is a shape obtained by translating the shape of the first surface toward the removal side of the mounting direction.

2. The media cassette of claim 1.

3. 3. The media cassette of claim 2, wherein the first surface has a shape of an arc.

4. In the main body side engaging portion, a plurality of the engaging elements are arranged at a predetermined pitch width along the attachment / detachment direction, The amount of protrusion of the first surface toward the detachment side in the attachment / detachment direction due to the curvature is greater than the pitch width.

4. The media cassette of claim 3.

5. In each of the engaging members, a tangent angle formed by a tangent to an end of the second surface in a direction perpendicular to the mounting direction on the medium placement table and the mounting direction is set to be 56.6 degrees or more and 69.4 degrees or more.

5. The media cassette of claim 4.

6. 2. The medium cassette according to claim 1, wherein the main body side engaging portion has support portions that support the engaging element at both ends of the engaging element in a direction perpendicular to the mounting and demounting direction on the medium loading platform.

7. A medium supplying device comprising the medium cassette according to any one of claims 1 to 5.

8. 6. An image forming apparatus comprising the medium cassette according to claim 1.

Images