Image forming apparatus

Abstract

To prevent an increase in size of an image forming apparatus, and reduce a situation in which a sound generated inside the apparatus and emitted from an ejection port is transmitted to the outside of the apparatus.SOLUTION: An image forming apparatus 1 comprises: an image forming unit 44 that forms an image on a recording medium; an ejection port 181 that ejects the recording medium on which the image is formed by the image forming unit; an ejection port surface 20 that is provided with the ejection port; an ejection tray 19 on which the recording medium ejected from the ejection port is loaded; a lower surface 41a of a document reading unit 41 that is provided opposite to the ejection tray 19; a side surface that is provided along an ejection direction A of the recording medium ejected from the ejection port; an in-barrel ejection space SP that is defined by at least the ejection port surface, the ejection tray, and a lower surface of the document reading unit, and a side surface, and accommodates the recording medium ejected from the ejection port; a plurality of sound absorption holes 111 that are provided at least in the ejection port surface, the ejection tray, and the lower surface of the document reading unit, and a side surface; and a sound absorption sheet 12 that is provided to cover the plurality of sound absorption holes on a side opposite to the in-barrel ejection space.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus equipped with a sound absorbing material. [Background technology]

[0002] In recent years, image forming devices such as copying machines have come to be widely used and installed in various environments. Therefore, the importance of quiet operation, which was previously a relatively low priority, is increasing. On the other hand, in office machines, as printing speeds increase, there is a tendency for sounds generated inside the device, such as drive sounds, paper sounds, and fan sounds, to increase, making noise reduction a major issue. In particular, the discharge space inside the body (discharged recording medium storage space) that stores recording media on which images are formed is always open so that users can quickly access the recording media, and sounds generated inside the device are released from the discharge port and leak out of the image forming device.

[0003] To address such problems, Patent Document 1 proposes providing a sound absorbing means using a Helmholtz resonator on the upper surface of the discharge space inside the body that contains the recording medium on which an image has been formed by the image forming unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-156766 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in recent years, there has been a demand for further miniaturization of image forming apparatuses, and the space available for installing sound absorbing means using Helmholtz resonators within the image forming apparatus is limited. The Helmholtz resonator is shaped like a container with a narrow entrance, and it is necessary to secure space for providing a cavity inside, which leads to an increase in the size of the main body of the image forming apparatus. In addition, the sound absorbing holes, which are the sound absorbing parts, are smaller in size than the internal cavity, so the number of sound absorbing holes that can be arranged is limited by the size of the cavity.

[0006] The present invention has been made in consideration of the above problems, and provides an image forming apparatus that can prevent the image forming apparatus from becoming larger and reduce the transmission of sound generated inside the apparatus and emitted from the discharge port to the outside of the apparatus. [Means for solving the problem]

[0007] In order to solve the above problems, an image forming apparatus according to an embodiment of the present invention comprises: an image forming unit that forms an image on a recording medium; an outlet for discharging the recording medium on which the image has been formed by the image forming unit; A wall portion provided with the exhaust port; a bottom portion on which the recording medium discharged from the discharge port is stacked; An upper portion provided opposite the bottom portion; a side portion provided along a discharge direction of the recording medium discharged from the discharge port; an ejection space defined by at least the wall portion, the bottom portion, the top portion, and the side portion, and configured to accommodate the recording medium ejected from the ejection port; A plurality of through holes provided in at least any of the wall portion, the bottom portion, the top portion, and the side portion; a sound absorbing material provided on the side of the portion in which the plurality of through holes are provided, opposite the exhaust space, so as to cover the plurality of through holes; The present invention is characterized by comprising: Effect of the Invention

[0008] According to the present invention, it is possible to prevent an image forming apparatus from becoming large in size, and to reduce transmission of sound generated inside the apparatus and emitted from the discharge port to the outside of the apparatus. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the image forming apparatus according to the first embodiment. [Diagram 3] FIG. 4 is a perspective view of an internal discharge space of the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view of the image forming apparatus when the discharge tray of the first embodiment is viewed from above. [Diagram 5] FIG. 4 is a schematic diagram showing the rear side of the internal paper ejection cover of the first embodiment. [Figure 6] 3 is a schematic diagram of a perforated surface of an internal paper ejection cover of the first embodiment. FIG. [Figure 7] 4 is a cross-sectional view of the perforated surface of the internal paper discharge cover and the sound absorbing sheet 12 of the first embodiment. [Figure 8] FIG. 11 is a perspective view showing an internal discharge space of an image forming apparatus according to another embodiment. [Figure 9] FIG. 11 is a diagram showing an internal paper discharge cover and a sound absorbing sheet according to another embodiment. [Figure 10] FIG. 11 is a cross-sectional view of an image forming apparatus according to a second embodiment. [Figure 11] FIG. 11 is a cross-sectional view of an image forming apparatus according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. EXAMPLES

[0011] The image forming apparatus 1 according to this embodiment will be described below with reference to the attached drawings. The sound absorbing means of this embodiment is used, for example, in the image forming apparatus 1 described below, but is not necessarily limited to this form. An embodiment of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the following embodiment should be appropriately changed depending on the configuration and various conditions of the device to which the present invention is applied. Therefore, unless otherwise specified, it is not intended to limit the scope of the present invention to only those.

[0012] (Image forming device) FIG. 1 is a perspective view of an image forming apparatus 1 of the first embodiment. FIG. 2 is a cross-sectional view of the image forming apparatus 1 of the first embodiment. The image forming apparatus 1 of the first embodiment is an internal paper discharge type. In the image forming apparatus 1 of the first embodiment, the side on which a user stands when operating the operation unit 10 is called the "front (or front)" and the opposite side is called the "back (or rear)". In addition, the left side as viewed from the front is called the "left" and the right side as viewed from the front is called the "right". Therefore, FIG. 2 shows a cross-section of the image forming apparatus 1 when viewed from the front.

[0013] 1 and 2, the image forming apparatus 1 includes a document reading section (reading device) 41, a sheet feeding section 42, a sheet transport section 43, an image forming section 44, a fixing section 45, and an operation section 10. The image forming section 44 includes four photoconductor drums 6Y, 6M, 6C, and 6K used to form a toner image. Each of the photoconductor drums 6Y, 6M, 6C, and 6K rotates clockwise in FIG. 2. Around each of the photoconductor drums 6Y, 6M, 6C, and 6K, chargers 8Y, 8M, 8C, and 8K, developers 4Y, 4M, 4C, and 4K, and cleaners 7Y, 7M, 7C, and 7K are disposed, respectively. The photoconductor drums 6Y, 6M, 6C, and 6K, the chargers 8Y, 8M, 8C, and 8K, the developers 4Y, 4M, 4C, and 4K, and the cleaners 7Y, 7M, 7C, and 7K constitute the imaging units 3Y, 3M, 3C, and 3K as process cartridges. The imaging units 3Y, 3M, 3C, and 3K constitute an image forming section 44 as an image forming means.

[0014] An intermediate transfer belt 14 is disposed above the image forming unit 44 as an intermediate transfer means so as to contact the photosensitive drums 6Y, 6M, 6C, and 6K. The intermediate transfer belt 14 is stretched around a driving roller 62 and two driven rollers 63 and 65. The intermediate transfer belt 14 rotates counterclockwise in FIG. 2. Primary transfer rollers 5Y, 5M, 5C, and 5K are disposed opposite the photosensitive drums 6Y, 6M, 6C, and 6K across the intermediate transfer belt 14. The primary transfer rollers 5Y, 5M, 5C, and 5K form primary transfer sections between the intermediate transfer belt 14 and the photosensitive drums 6Y, 6M, 6C, and 6K, respectively. Toner supply sections 32Y, 32M, 32C, and 32K that supply toner of each color to the developing units 4Y, 4M, 4C, and 4K are disposed above the intermediate transfer belt 14.

[0015] The imaging unit 3Y forms a yellow toner image, the imaging unit 3M forms a magenta toner image, the imaging unit 3C forms a cyan toner image, and the imaging unit 3K forms a black toner image. The imaging units 3Y, 3M, 3C, and 3K have almost the same structure, so the imaging unit 3Y will be described below. The surface of the photoconductor drum 6Y is uniformly charged by the charger 8Y. The exposure unit 15 irradiates the uniformly charged surface of the photoconductor drum 6Y with light modulated by a yellow image signal to form a latent image on the surface of the photoconductor drum 6Y. The developing unit 4Y develops the latent image on the surface of the photoconductor drum 6Y with yellow toner supplied from the toner supply unit 32Y, and forms a yellow toner image on the photoconductor drum 6Y.

[0016] As the photoconductor drum 6Y rotates, the yellow toner image reaches a primary transfer portion where the photoconductor drum 6Y comes into contact with the intermediate transfer belt 14. A primary transfer bias is applied from an electrical board (not shown) to the primary transfer roller 5Y disposed opposite the photoconductor drum 6Y, causing the primary transfer roller 5Y to transfer the yellow toner image on the surface of the photoconductor drum 6Y to the intermediate transfer belt 14. Similarly, the magenta, cyan and black toner images formed on the surfaces of the photoconductor drums 6M, 6C and 6K are transferred sequentially to the intermediate transfer belt 14 by the primary transfer rollers 5M, 5C and 5K.

[0017] The sheet S as a recording medium stored in the sheet feeding section 42 as a feeding unit is sent out by the pickup roller 67, and is separated one by one by the separation feeding section 16 and fed to the registration roller 9. The registration roller 9 starts conveying the sheet S in synchronization with the toner image transferred onto the intermediate transfer belt 14, and conveys the sheet S to the secondary transfer section T2 formed between the secondary transfer roller 28 and the intermediate transfer belt 14. The secondary transfer roller 28 transfers the toner image on the intermediate transfer belt 14 to the sheet S at the secondary transfer section T2. ​​The sheet S with the transferred toner image is conveyed to the fixing section 45. The fixing section 45 heats and pressurizes the sheet S, whereby the toner is melted and mixed and fixed to the sheet S to form a color image on the sheet S. The sheet S with the image formed thereon is discharged to the discharge tray 19 by the discharge roller 18 provided downstream of the fixing section 45. The discharge roller 18 has a discharge port 181 for discharging the sheet S.

[0018] The image forming apparatus 1 can operate in a single-sided printing mode in which an image is formed on one side of the sheet S, and a double-sided printing mode in which an image is formed on both sides of the sheet S. In the single-sided printing mode, as described above, the sheet S on which an image is formed on one side of the sheet S is discharged to the discharge tray 19 by the discharge rollers 18. In the double-sided printing mode, the sheet S on which an image is formed on one side (first side) is conveyed to the reverse conveying path 21 by the reverse conveying rollers 18. The sheet S is conveyed again to the secondary transfer portion T2 by the reverse conveying rollers 17 arranged in the reverse conveying path 21. In the secondary transfer portion T2, a toner image is transferred to the back side (second side) of the sheet S. The sheet S is conveyed to the fixing portion 45, where the toner image is fixed to the back side of the sheet S to form a color image. The sheet S on which images are formed on both sides is discharged to the discharge tray 19 by the discharge rollers 18.

[0019] (Exhaust space inside the fuselage) Next, referring to FIG. 3, the internal discharge space SP as the discharge space of the image forming apparatus 1 of the first embodiment will be described. FIG. 3 is a perspective view of the internal discharge space SP of the first embodiment. In the image forming apparatus 1, the document reading unit 41 is disposed above the discharge tray 19 on which the sheets S discharged from the discharge port 181 are stacked. Between the discharge tray 19 and the document reading unit 41, the internal discharge space SP is formed in which the sheets S discharged from the discharge port 181 are stored. In the image forming apparatus 1, the image forming unit 44 is provided below the internal discharge space SP. In the image forming apparatus 1, an internal discharge cover 11 is provided on the rear side of the internal discharge space SP. In the image forming apparatus 1, a discharge port surface (wall portion) 20 in which the discharge port 181 is formed is provided on the right side of the internal discharge space SP. The internal discharge space SP is defined by at least four surfaces including the discharge tray 19 as the bottom surface (bottom part), the discharge outlet surface 20, the lower surface 41a of the document reading section 41 as the top surface (upper part), and the internal paper discharge cover 11 as the side surface (side part).

[0020] 4 is a cross-sectional view of the image forming apparatus 1 in which the discharge tray 19 of the first embodiment is viewed from above. The sheets S discharged from the discharge opening 181 are stored in the internal discharge space SP while being stacked on the discharge tray 19 in the internal discharge space SP. An internal discharge cover 11 serving as a perforated plate is provided on the rear side of the internal discharge space SP. The sheets S discharged from the discharge opening 181 are discharged in the direction indicated by the arrow in FIG. 4 (hereinafter referred to as discharge direction A). The internal discharge cover 11 constitutes a side surface (side portion) of the internal discharge space SP that is provided along the discharge direction A.

[0021] A sound absorbing sheet (sound absorbing material) 12 is provided in contact with the back side of the internal paper discharge cover 11. The internal paper discharge cover 11 and the sound absorbing sheet 12 constitute a sound absorbing device 13 that absorbs sound emitted from the discharge port 181. The sound absorbing sheet 12 is a sheet of a sound absorbing material such as an ethylene propylene diene rubber (EPDM) or urethane foam, glass fiber glass wool material, or mineral rock wool material. However, instead of the sound absorbing sheet 12, a plate-shaped, block-shaped, cotton-shaped, or other sound absorbing material may be used. The internal paper discharge cover 11 is provided with a plurality of sound absorbing holes 111 as described later with reference to Figs. 5 to 7. The plurality of sound absorbing holes 111 are a plurality of through holes that penetrate the internal paper discharge cover 11. All of the plurality of sound absorbing holes 111 are covered by the sound absorbing sheet 12 on the back side of the internal paper discharge cover 11. "The multiple sound absorbing holes 111 are covered by the sound absorbing sheet 12 on the back side of the internal paper discharge cover 11" means that the internal paper discharge cover 11 and the sound absorbing sheet 12 are adjacent to each other and overlap with the multiple sound absorbing holes 111 and the sound absorbing sheet 12 when viewed from a direction perpendicular to the internal paper discharge cover 11. A part of the main body operation sound emitted from the discharge port 181 passes through the sound absorbing holes 111 and enters the sound absorbing sheet 12, and as the sound is widely diffused therein, a part of the sound energy is converted into heat energy. This reduces the sound leaking out of the device main body.

[0022] The multiple sound absorbing holes 111 and the sound absorbing sheet 12 covering them may be provided over the entire area of ​​the internal paper discharge cover 11, or may be provided in a part of the internal paper discharge cover 11. The multiple sound absorbing holes 111 and the sound absorbing sheet 12 covering them may be provided in multiple parts of the internal paper discharge cover 11. Also, the multiple sound absorbing holes 111 and the sound absorbing sheet 12 covering them may be provided in a part of the internal paper discharge cover 11 on the opposite side of the discharge opening 181 with respect to the central position in the discharge direction A of the sheet S. By providing the multiple sound absorbing holes 111 and the sound absorbing sheet 12 covering them near the opening of the internal discharge space SP, it is possible to reduce the sound transmitted from the internal discharge space SP to the user.

[0023] In this embodiment, the internal paper ejection cover 11 and the sound absorbing sheet 12 are in contact with each other. When the internal paper ejection cover 11 and the sound absorbing sheet 12 are in contact with each other, the vibration of the internal paper ejection cover 11 is reduced by the sound absorbing sheet 12. Therefore, the contact between the internal paper ejection cover 11 and the sound absorbing sheet 12 can further effectively lead to quieter operation of the image forming apparatus 1. In this embodiment, the sound absorbing sheet (sound absorbing material) 12 is provided in contact with the internal paper ejection cover 11, but the sound absorbing sheet 12 may be disposed away from the internal paper ejection cover 11.

[0024] Generally, the thicker the sound absorbing sheet 12, the easier it is to adapt to a wider frequency band of sounds and obtain a silencing effect, and this is therefore preferable. In this embodiment, in order to obtain a high effect at low cost, a sound absorbing sheet 12 made of EPDM foam and having a thickness of "5 mm" is used. Note that when an EPDM or urethane sound absorbing sheet 12 is used, if the sound absorbing sheet 12 is crushed, it becomes difficult to obtain a silencing effect. Therefore, the sound absorbing sheet 12 is attached between the wall surface of the device main body and the internal paper discharge cover 11 to prevent it from being crushed.

[0025] The internal discharge space SP is not limited to those shown in Figs. 3 and 4. Fig. 8 is a perspective view showing the internal discharge space SP1 of an image forming apparatus 101 according to another embodiment. In the image forming apparatus 101, the internal discharge space SP1 is configured so that a user standing in front of the operation unit 10 faces the discharge port 181. The internal discharge space SP1 of the image forming apparatus 101 can be defined by five surfaces including the discharge tray 19 as the bottom surface, the discharge port surface 20, the lower surface 41a of the document reading unit 41 as the upper surface provided opposite the discharge tray, the left side surface 22, and the right side surface 23. In this case, the sound absorbing device 13 consisting of the internal paper discharge cover 11 and the sound absorbing sheet 12 may be provided only on the left side surface (side surface) 22, or only on the right side surface (another side surface) 23, or may be provided on both the left side surface 22 and the right side surface 23.

[0026] (Inner paper exit cover) Next, the internal paper ejection cover 11 of this embodiment will be described with reference to FIG. 5. FIG. 5 is a schematic diagram showing the rear side of the internal paper ejection cover 11 of Example 1. The internal paper ejection cover 11 of this embodiment has a perforated surface (perforated wall surface portion) 112, a sound absorbing sheet adhesive surface 113, and a main body attachment portion 114. One or more sound absorbing holes 111 are formed in the perforated surface 112. The main body attachment portion 114 is provided with a hole 114a through which a screw passes. The internal paper ejection cover 11 is fixed to the main body of the image forming device 1 by passing a screw through the hole 114a and screwing it into a screw hole provided in the main body of the image forming device 1. At this time, a gap is formed between the internal paper ejection cover 11 and the main body of the image forming device 1 in which the sound absorbing sheet 12 is disposed so that the sound absorbing sheet 12 is not crushed.

[0027] An adhesive member such as an adhesive, glue, or double-sided tape is applied to the sound-absorbing sheet adhesive surface 113 for attaching the sound-absorbing sheet 12 to the internal paper discharge cover 11. Note that a fastening member such as a screw or bolt for attaching the sound-absorbing sheet 12 to the internal paper discharge cover 11 may be attached to the sound-absorbing sheet adhesive surface 113. In this embodiment, the sound-absorbing sheet 12 is attached to the internal paper discharge cover 11 with an adhesive double-sided tape. However, if the double-sided tape blocks even a part of the sound-absorbing holes 111, the sound-absorbing sheet 12 has a reduced silencing effect compared to when the holes are not blocked. Therefore, the double-sided tape is used to attach the sound-absorbing sheet 12 to the sound-absorbing sheet adhesive surface 113 (area indicated by diagonal lines) where the sound-absorbing holes 111 are not formed, in other words, to an area other than the area where the sound-absorbing holes 111 are formed.

[0028] The internal paper discharge cover 11 is not limited to the structure shown in FIG. 5. For example, the internal paper discharge cover 11 may be configured to hold the sound absorbing sheet 12 without using an adhesive member. FIG. 9 is a diagram showing an internal paper discharge cover 201 and a sound absorbing sheet 202 of another embodiment. FIG. 9(a) is a perspective view of the internal paper discharge cover 201 to which the sound absorbing sheet 202 is attached, seen from the opposite side (main body side, back side) with respect to the internal discharge space SP. The internal paper discharge cover 201 is provided with a hook-shaped portion (locking portion) 203, a slip-prevention portion 204, a boss 205, a central protrusion 206, and a lower protrusion 207. FIG. 9(b) is a front view of the sound absorbing sheet 202. The sound absorbing sheet 202 is provided at the upper left and upper right parts with cutout portions (locked portions) 208 that penetrate the sound absorbing sheet 202. FIG. 9(c) is a cross-sectional view taken along the line IXC-IXC in FIG. 9(a). 9(c), the hook-shaped portion 203 of the internal paper ejection cover 201 is inserted into the notch 208 of the sound absorbing sheet 202, so that the sound absorbing sheet 202 is hooked onto the hook-shaped portion 203. As a result, the sound absorbing sheet 202 is supported by the internal paper ejection cover 201 in a state in which it is suspended from the hook-shaped portion 203. When the internal paper ejection cover 201 is attached to the main body of the image forming apparatus 1, at least one of the hook-shaped portion 203, the stopper portion 204, the boss 205, the central protrusion 206, and the lower protrusion 207 of the internal paper ejection cover 201 abuts against the main body of the image forming apparatus 1. As a result, a gap is formed between the internal paper ejection cover 201 and the main body of the image forming apparatus 1 in which the sound absorbing sheet 202 is disposed, so that the sound absorbing sheet 202 is not crushed.

[0029] 9(c) 。 Note that the hook-shaped portion 203 provided on the internal paper discharge cover 201 is not limited to the shape shown in Fig. 9(c) and may be a locking portion such as a protrusion. The cutout portion 208 provided on the sound absorbing sheet 202 is not limited to the shape shown in Fig. 9(b) and may be a locking portion such as a hole, a recess, or a through hole that can be locked to the locking portion provided on the internal paper discharge cover 201.

[0030] As already mentioned, in order to reduce the sound emitted from the internal discharge space SP to the outside of the image forming apparatus 1, it has been considered to provide a sound silencing mechanism in the internal discharge space SP. For example, a Helmholtz resonator is provided as a sound silencing mechanism in the internal discharge space SP to reduce the sound emitted from the internal discharge space SP to the outside of the image forming apparatus 1. However, in recent years, there has been a demand for further miniaturization of the image forming apparatus 1, and the space in the internal discharge space SP in which the Helmholtz resonator can be installed is limited. Specifically, if the frequency of the operation sound in the apparatus is assumed to be "500Hz", the speed of sound in air is "approximately 331000mm / s", so it is necessary to install a Helmholtz resonator with a depth of about "50mm". However, recent image forming apparatuses 1 do not have a large enough space to install a Helmholtz resonator of such a size.

[0031] Therefore, in this embodiment, a configuration is proposed in which the sound absorbing sheet 12 formed to a thickness of "5 mm" is held by the internal paper discharge cover 11 having a thickness of about "3 mm" to reduce noise. This makes it possible to reduce the sound emitted from the internal discharge space SP to the outside of the image forming apparatus 1 while suppressing the increase in size of the main body. As shown in FIG. 4, in Example 1, the depth (distance) L of the gap where the sound absorbing sheet 12 is disposed between the internal paper discharge cover 11 and the main body of the image forming apparatus 1 is set to about 6 mm in consideration of the thickness of the double-sided tape. Therefore, according to Example 1, the space required for disposing the sound absorbing device 13 can be significantly reduced compared to the case where a Helmholtz resonator is installed.

[0032] (Perforated wall part) Next, the configuration of the perforated surface 112 of the internal paper discharge cover 11 will be described with reference to FIG. 6. FIG. 6 is a schematic diagram of the perforated surface 112 of the internal paper discharge cover 11 of the first embodiment. In the first embodiment, the sound absorbing holes 111 formed on the perforated surface 112 are oblong holes with a radius d of "1.5 mm or more and 6 mm or less" and a width w of "3 mm or more and 30 mm or less" as shown in FIG. 6(a). It is not necessary to make the hole diameter of all the sound absorbing holes 111 the same. If the radius d of the sound absorbing holes 111 is smaller than 1.5 mm, the strength of the mold for resin molding the internal paper discharge cover 11 may be weakened. Therefore, the radius d is set to 1.5 mm or more. On the other hand, if the radius d is larger than 6 mm, that is, the diameter is larger than 12 mm, the width of an adult's finger is generally larger than 12 mm, so that the finger of a user taking out the sheet S loaded in the internal discharge space SP may mistakenly enter the sound absorbing hole 111. Therefore, the radius d is set to 6 mm or less. In the first embodiment, the radius d of all the sound absorbing holes 111 was set to "3 mm" and the width w was set to "20 mm."

[0033] The shape of the sound absorbing hole 111 is not limited to an elongated hole, and may be a round hole 121 with a radius d of 1.5 mm to 6 mm as shown in FIG. 6(b). Also, as shown in FIG. 6(c), it may be a square hole 131 with one side of 1.5 mm to 30 mm. If one side is longer than 30 mm, the strength and rigidity of the internal paper discharge cover 11 may not be maintained. However, as long as the strength and rigidity are sufficient to prevent the cover from breaking even when pressed from the outside, one side may be longer than 30 mm. Also, it is preferable that the sound absorbing holes 111, the round holes 121, or the square holes 131 of the elongated holes are evenly distributed, and in the first embodiment, the sound absorbing holes 111, the round holes 121, or the square holes 131 of the elongated holes are arranged at intervals a of 8 mm. In addition, in the portion of the internal paper discharge cover 11 with which the sheet S discharged from the discharge port 181 may come into contact, the sheet S may get caught in the square hole 131, so the shape of the sound absorbing hole 111 is preferably an elongated round hole or a round hole 121. The shape of the sound absorbing hole 111 does not necessarily have to be the same type of shape, and the sound absorbing holes 111 of a plurality of different shapes may be provided on the perforated surface 112.

[0034] FIG. 7 is a cross-sectional view of the perforated surface 112 and the sound absorbing sheet 12 of the internal paper discharge cover 11 of the first embodiment. FIG. 7 is a cross-sectional view taken on a plane parallel to the thickness direction (front-rear direction) of the internal paper discharge cover 11. As shown in FIG. 7, the sound absorbing holes 111 are inclined at an inclination angle θ toward the discharge port 181 with respect to the surface of the internal paper discharge cover 11. In the first embodiment, the sound absorbing holes 111 are inclined 30 degrees (θ=30 degrees) toward the discharge port 181 with respect to the surface of the internal paper discharge cover 11. However, the inclination angle θ of the sound absorbing holes 111 with respect to the surface of the internal paper discharge cover 11 is not limited to 30 degrees. The inclination angle θ may be any number of degrees, but since the discharge port 181 and the internal paper discharge cover 11 are disposed at a substantially right angle when the main body of the image forming apparatus 1 is viewed from above, it is preferable that the inclination angle θ is set in a range of 45 degrees or less. In this case, the main body operation sound emitted from exhaust port 181 is more likely to enter sound absorption holes 111, further improving the noise reduction effect.

[0035] In addition, the ratio of the area occupied by the multiple sound absorbing holes 111 to the surface area of ​​the part of the main body (main body part) corresponding to the perforated surface 112 and the multiple sound absorbing holes 111 (total area of ​​the back surface of the internal discharge space SP) is preferably "35% or more". This is because if the ratio of the area occupied by the multiple sound absorbing holes 111 is less than 35%, an effective sound absorbing effect cannot be obtained. If the ratio of the area occupied by the multiple sound absorbing holes 111 is more than 50%, the rigidity of the resin internal discharge cover 11 generally becomes very low, and effective rigidity of the internal discharge cover 11 may not be obtained. Therefore, the ratio of the area of ​​the multiple sound absorbing holes 111 to the surface area of ​​the perforated surface 112 and the multiple sound absorbing holes 111 (total area of ​​the back surface of the internal discharge space SP) is preferably "35% or more and 50% or less". In Example 1, taking into consideration the processability of the sound absorption holes 111 on the internal paper output cover 11 and the rigidity of the internal paper output cover 11, the ratio of the area occupied by the multiple sound absorption holes 111 to the area of ​​the perforated surface 112 and the multiple sound absorption holes 111 is 35% or more and 50% or less per unit area.

[0036] As described above, by using the internal paper discharge cover 11 in which the multiple sound absorbing holes 111 are formed and the multiple sound absorbing holes 111 are covered by the sound absorbing sheet 12, the main body operation sound emitted from the discharge port 181 can be silenced in a small space. That is, when a part of the main body operation sound emitted from the discharge port 181 diffuses through the sound absorbing holes 111 in the sound absorbing sheet 12, a part of the sound energy is converted into heat energy, and the main body operation sound is silenced. As a result, according to the first embodiment, a large sound silencing effect can be obtained in a small space without using a conventional Helmholtz resonator, so that the main body of the image forming apparatus 1 can be prevented from becoming large. According to the first embodiment, the image forming apparatus 1 can be prevented from becoming large, and the sound generated inside the apparatus and emitted from the discharge port can be reduced from being transmitted to the outside of the apparatus. In this embodiment, a sound absorbing configuration consisting of the internal paper discharge cover 11 having the multiple sound absorbing holes 111 and the sound absorbing sheet 12 is arranged on the back surface of the internal discharge space SP. This reduces the amount of sound reflected from the back surface toward the front side of image forming apparatus 1 (the side where a user operating operation unit 10 stands), which is preferable for the user. EXAMPLES

[0037] Next, a second embodiment will be described with reference to Fig. 10. The configuration of the second embodiment is different from that of the first embodiment in that an internal paper discharge cover 211 is provided at the top of the internal discharge space SP. However, other configurations are the same as those of the first embodiment, so similar configurations are denoted by similar reference numerals and detailed descriptions are omitted.

[0038] Fig. 10 is a cross-sectional view of an image forming apparatus 1 according to a second embodiment. In the second embodiment, as shown in Fig. 10, a configuration is adopted in which an internal paper discharge cover 211 having a plurality of sound absorbing holes 111 is provided above the internal discharge space SP. The internal paper discharge cover 211 in the second embodiment forms the upper surface of the internal discharge space SP. A sound absorbing device 213 consisting of the internal paper discharge cover 211 and a sound absorbing sheet 212 is attached to the outer surface (lower surface) of the bottom plate (lower part) of the document reading unit 41. In the second embodiment, the sound absorbing sheet (sound absorbing material) 212 is provided in contact with the internal paper discharge cover 211, but the sound absorbing sheet 212 may be disposed away from the internal paper discharge cover 211.

[0039] By covering the sound absorbing holes 111 with the sound absorbing sheet 212, part of the main body operation sound emitted from the exhaust port 181 enters the sound absorbing sheet 212 through the sound absorbing holes 111. When the sound is widely diffused within the sound absorbing sheet 212, part of the sound energy is converted into heat energy, making the sound quieter. It is desirable that the ratio of the area occupied by the multiple sound absorbing holes 111 to the total area of ​​the bottom plate (lower surface) of the document reading unit 41 is "not less than 35% and not more than 50%."

[0040] The sound absorbing holes 111 and the sound absorbing sheet 212 may be provided in the entire area of ​​the internal paper discharge cover 211, or may be provided in a part of the internal paper discharge cover 211. The sound absorbing holes 111 and the sound absorbing sheet 212 may be provided in a plurality of parts of the internal paper discharge cover 211. The sound absorbing holes 111 and the sound absorbing sheet 212 may be provided in a portion of the internal paper discharge cover 211 on the side where the operation unit 10 is provided with respect to the central position in a direction (front-rear direction) perpendicular to the discharge direction A of the recording medium and perpendicular to the up-down direction. According to the second embodiment, it is possible to prevent the image forming apparatus 1 from becoming large, and to reduce the transmission of sound generated inside the apparatus and emitted from the discharge port to the outside of the apparatus. EXAMPLES

[0041] Next, a third embodiment will be described with reference to Fig. 11. The configuration of the third embodiment differs from that of the first embodiment in that an internal paper discharge cover 311 is provided on the discharge tray 19 as the bottom surface (bottom portion) of the internal discharge space SP, and an internal paper discharge cover 411 is provided on the discharge port surface 20 as the wall portion. However, other configurations are the same as those of the first embodiment, and therefore similar configurations are denoted by similar reference numerals and detailed description thereof will be omitted.

[0042] 11 is a cross-sectional view of the image forming apparatus 1 of the third embodiment. In the third embodiment, as shown in FIG. 11, an internal paper discharge cover 311 having a plurality of sound absorbing holes 111 is provided below the internal discharge space SP, and an internal paper discharge cover 411 having a plurality of sound absorbing holes 111 in a wall portion where the discharge port 181 is provided is provided. The internal paper discharge cover 311 in the third embodiment forms the lower surface of the internal discharge space SP. A sound absorbing device 313 consisting of the internal paper discharge cover 311 and a sound absorbing sheet 312 is attached to the discharge tray 19 as a sheet stacking surface. In the third embodiment, the sound absorbing sheet (sound absorbing material) 312 is provided in contact with the internal paper discharge cover 311, but the sound absorbing sheet 312 may be disposed away from the internal paper discharge cover 311. By covering the sound absorbing holes 111 of the internal paper discharge cover 311 with the sound absorbing sheet 312, part of the main body operation sound emitted from the discharge port 181 enters the sound absorbing sheet 312 through the sound absorbing holes 111. When the sound is widely diffused within the sound absorbing sheet 312, part of the sound energy is converted into heat energy, making the sound quieter. It is desirable that the ratio of the area occupied by the multiple sound absorbing holes 111 to the total area of ​​the discharge tray 19 be "35% or more and 50% or less."

[0043] The internal paper discharge cover 411 in the third embodiment constitutes a wall of the internal discharge space SP. The sound absorbing device 413 consisting of the internal paper discharge cover 411 and the sound absorbing sheet 412 is attached to the discharge port surface 20 on which the discharge port 181 is formed. In the third embodiment, the sound absorbing sheet (sound absorbing material) 412 is provided in contact with the internal paper discharge cover 411, but the sound absorbing sheet 412 may be disposed away from the internal paper discharge cover 411. By covering the sound absorbing holes 111 of the internal paper discharge cover 411 with the sound absorbing sheet 412, a part of the main body operation sound emitted from the discharge port 181 enters the sound absorbing sheet 412 through the sound absorbing holes 111. When the sound is widely diffused in the sound absorbing sheet 412, a part of the energy of the sound is converted into heat energy, and the sound becomes quieter. It is desirable that the ratio of the area occupied by the multiple sound absorbing holes 111 to the total area of ​​the discharge port surface 20 is "35% or more and 50% or less." In the third embodiment, both the internal discharge covers 311 and 411 are provided in the internal discharge space SP, but only one of the internal discharge covers 311 or 411 may be provided.

[0044] The sound absorbing structure may be arranged on any member facing the internal discharge space SP. For example, the sound absorbing structure (sound absorbing device 313) may be arranged on the sheet stacking surface (discharge tray 19) (see FIG. 11). Also, the sound absorbing structure (sound absorbing device 413) may be arranged on the discharge port surface 20 on which the discharge port 181 is formed (see FIG. 11). Also, the sound absorbing structure (sound absorbing device 13) may be arranged on the side surface of the internal discharge space SP (see FIG. 4). Also, the sound absorbing structure (sound absorbing device 213) may be arranged on the upper surface of the internal discharge space SP (see FIG. 10).

[0045] Sound absorbing structures may be arranged on multiple surfaces facing the internal discharge space SP. For example, sound absorbing structures may be arranged on both the bottom plate of the document reading unit 41 and the back surface of the internal discharge space SP. Sound absorbing structures may also be arranged on the bottom plate of the document reading unit 41, the back surface of the internal discharge space SP, and the sheet stacking surface (discharge tray 19). Sound absorbing structures may also be arranged on the bottom plate of the document reading unit 41, the back surface of the internal discharge space SP, the sheet stacking surface (discharge tray 19), and the discharge port surface 20 on which the discharge port 181 is formed.

[0046] Noise reduction can also be achieved by installing a sound absorbing structure consisting of an internal paper discharge cover 11 with multiple sound absorbing holes 111 and a sound absorbing sheet 12 as a kit, i.e., as an optional unit, in a location facing the discharge space of the image forming device. [Explanation of symbols]

[0047] 1...Image forming device 12...Sound absorbing sheet 19…Outlet tray 20…Discharge port surface 41a…Bottom surface 44...Image forming section 111...Sound absorbing hole 181...Exhaust port A…Discharge direction SP…Inner body discharge space

Claims

1. an image forming unit that forms an image on a recording medium; an outlet for discharging the recording medium on which the image has been formed by the image forming unit; A wall portion provided with the exhaust port; a bottom portion on which the recording medium discharged from the discharge port is stacked; An upper portion provided opposite the bottom portion; a side portion provided along a discharge direction of the recording medium discharged from the discharge port; an ejection space defined by at least the wall portion, the bottom portion, the top portion, and the side portion, and configured to accommodate the recording medium ejected from the ejection port; A plurality of through holes provided in at least any of the wall portion, the bottom portion, the top portion, and the side portion; a sound absorbing material provided on the side of the portion in which the plurality of through holes are provided, opposite the exhaust space, so as to cover the plurality of through holes; An image forming apparatus comprising:

2. A plurality of through holes are provided in the side portion, The image forming apparatus according to claim 1 , wherein the sound absorbing material is provided on a side of the side portion opposite to the discharge space.

3. The image forming apparatus according to claim 2 , wherein the plurality of through holes are provided in a portion of the side portion.

4. 3. The image forming apparatus according to claim 2, wherein a ratio of an area occupied by the plurality of through holes to an area of ​​the side portion is 35% or more and 50% or less per unit area.

5. A plurality of through holes are provided in the upper portion, The image forming apparatus according to claim 1 , wherein the sound absorbing material is provided on a side of the upper portion opposite to the discharge space.

6. Further comprising an operation unit operated by a user, The image forming apparatus according to claim 5 , wherein the plurality of through holes are provided on a side of the upper portion where the operation unit is provided.

7. Further comprising another side portion provided opposite the side portion, the plurality of through holes are provided on the other side portion or on both the side portion and the other side portion, The sound absorbing material is provided on the opposite side of the exhaust space with respect to the other side portion, The image forming apparatus according to claim 1 , wherein the sound absorbing material is provided on a side of the side portion opposite to the discharge space when the plurality of through holes are provided in the side portion.

8. The image forming apparatus according to claim 1 , wherein the sound absorbing material is in a sheet form.

9. The sound absorbing material is formed in a sheet shape from any one of ethylene propylene diene rubber or urethane foam, glass wool, and rock wool, The image forming apparatus according to claim 1 , wherein the sound absorbing material abuts against the portion where the plurality of through holes are provided.

10. 8. The image forming apparatus according to claim 1, wherein the plurality of through holes are circular holes having a radius of 1.5 mm to 6 mm or oblong holes having a radius of 1.5 mm to 6 mm and a width of 3 mm to 30 mm.

11. The image forming apparatus according to claim 1 , wherein the plurality of through holes are rectangular holes each having a side of 1.5 mm to 30 mm.

12. The image forming apparatus according to claim 1 , wherein the plurality of through holes are inclined toward the wall portion.

13. 8. The image forming apparatus according to claim 1, wherein the sound absorbing material is adhered to any one of the wall portion, the bottom portion, the top portion, and the side portion by an adhesive member.

14. A locking portion is provided on any one of the wall portion, the bottom portion, the upper portion, and the side portion, The sound absorbing material is provided with a latched portion, The image forming apparatus according to claim 1 , wherein the engaged portion of the sound absorbing material is engaged with the engaging portion of the portion in which the plurality of through holes are provided.

15. a reading device provided above the discharge space for reading an image of a document; The image forming apparatus according to claim 1 , wherein the reading device comprises the upper portion.

16. an image forming unit that forms an image on a recording medium; an outlet for discharging the recording medium on which the image has been formed by the image forming unit; a discharge space in which the recording media discharged from the discharge port are accommodated in a stacked state; a member facing the discharge space and defining the discharge space; A plurality of through holes provided in the member; a sound absorbing material provided on the member on the opposite side to the exhaust space so as to cover the plurality of through holes; An image forming apparatus comprising:

17. 17. The image forming apparatus according to claim 16, wherein the member in which the plurality of through holes are provided is a side portion provided along a discharge direction of the recording medium discharged from the discharge port.

18. a bottom portion on which the recording medium discharged from the discharge port is stacked, The image forming apparatus according to claim 16 , wherein the member having the plurality of through holes is provided opposite to the bottom portion.

19. 17. The image forming apparatus according to claim 16, wherein the member in which the plurality of through holes are provided is a bottom portion on which the recording medium discharged from the discharge port is stacked.

20. The image forming apparatus according to claim 16 , wherein the member in which the plurality of through holes are provided is a wall portion in which the discharge port is provided.

21. 21. The image forming apparatus according to claim 16, wherein the sound absorbing material is in a sheet form.

Images