JP2012132900A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of improving the hearing impression of a user.SOLUTION: An image forming device 1 includes a driving portion which is disposed close to a first wall portion 28, and supplies driving force required for image forming action; and a carrying portion which is disposed close to a second wall portion 27 and carries a sheet according to the image forming action. Assuming stationary sound generated when the driving portion supplies the driving force as first noise, nonstationary sound generated when the carrying portion carries the sheet as second noise, a first equivalent noise level value of the first noise collected at a first sound collecting position P1 as LA, and a second equivalent noise level value of the second noise collected at a second sound collecting position P2 as LB, the following condition (1) is satisfied. LA>Lb...(1).

Description

  The present invention relates to an image forming apparatus that forms an image on a sheet.

  2. Description of the Related Art Image forming apparatuses such as printers and copiers include a drive unit that supplies a driving force necessary for an image forming operation for forming an image on a sheet, and a transport unit that transports the sheet.

  Since the drive unit includes a motor, a gear, and the like for transmitting a driving force, and a cooling fan for cooling the interior of the machine, a steady sound is generated using these as a sound source. Further, the conveying unit also generates impact sound due to contact between the sheet and the guide when the sheet is conveyed, an electromagnetic clutch, and the like. Recent image forming apparatuses are required to be quiet and quiet. For example, Japanese Patent Application Laid-Open No. H10-228667 is known as a technique for achieving quietness and pleasantness without impairing the function of the image forming apparatus.

  In the image forming apparatus of Patent Document 1, a certain relationship is obtained from multiple regression analysis using parameters of each physical quantity, for example, a loudness value, a sharpness value, a tonality value, and an impulsiveness value, by statistically analyzing sound quality physical quantities from experiments. By satisfying the requirements, the noise is reduced and the sound is improved.

JP 2004-205269 A

  However, when performing an image forming operation, the image forming apparatus generates a complex composite sound such that the operation sound changes with time due to its structure. For this reason, it is difficult to unambiguously evaluate the user's auditory impression using a complicated correlation equation using the above parameters.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus capable of improving a user's audible impression and an evaluation unit that generalizes user's impression evaluation.

In order to achieve the above object, an image forming apparatus according to an aspect of the present invention is an apparatus main body having a housing that defines an accommodation space, and a first wall portion that defines one wall surface of the housing. And a second wall portion defining another wall surface different from the one wall surface, and an apparatus main body in which an image forming operation for forming an image on a sheet is performed in the housing space, and the housing space A drive unit that is disposed in the vicinity of the first wall and that supplies a driving force necessary for the image forming operation; and is disposed in the storage space in the vicinity of the second wall, and the sheet And a conveyance unit that conveys the image according to the image forming operation. The stationary sound generated when the driving unit supplies the driving force is referred to as a first noise, the non-stationary sound generated when the conveying unit conveys the sheet is referred to as a second noise, and the first wall. The first equivalent noise level value of the first noise picked up at the first sound pickup position separated from the outer surface of the part by the first distance is defined as LA, and the first distance from the outer surface of the second wall part When the second equivalent noise level value of the second noise picked up at the second sound pickup position separated by the same second distance is LB, the following condition (1) is satisfied.
LA> LB (1)

  In the image forming apparatus according to the present invention, the first equivalent noise level value LA is set larger than the second equivalent noise level value LB. Therefore, the second noise that is a non-stationary sound is easily masked by the first noise that is a stationary sound. Accordingly, the user listens to the entire noise generated by the image forming apparatus in a state where the first noise that is a stationary sound is emphasized more than the second noise that is an unsteady sound. As a result, the user's audible impression is improved, that is, the noise of the image forming apparatus is achieved.

In a preferred embodiment of the present invention, when the first sound pressure level of the first noise is DA and the second sound pressure level of the second noise is DB, the following conditions ( 2) is satisfied.
DA> DB (2)

  According to this configuration, the first sound pressure level DA of the first noise is set to be larger than the second sound pressure level DB of the second noise in a frequency band around 1 kHz that is particularly disturbing for the user. Therefore, the user's audible impression can be improved.

  In another preferred embodiment of the present invention, the transport section includes a guide member for transporting the sheet and a transport path defined by the guide member, and the unsteady sound is generated when the sheet is It includes an impact sound generated by colliding with the guide member when being transported on the transport path.

  The impact sound that the sheet collides with the guide member is particularly disturbing sound. However, according to the image forming apparatus of the present invention, the impact sound is masked by the first noise, so that the user's audible impression can be improved.

  In still another preferred embodiment of the present invention, the first wall portion has a first edge portion extending in the vertical direction of the device main body, and the second wall portion extends in the vertical direction of the device main body. And having a second edge in a state of being close to the first edge, and being arranged substantially orthogonal to the first wall.

  According to this configuration, since the first wall portion and the second wall portion are arranged substantially orthogonal to each other, it is possible to easily obtain an action (masking) for masking the second noise by the first noise.

In still another preferred embodiment of the present invention, the first sharpness value of the first noise picked up at a first sound pickup position separated from the outer surface of the first wall by a first distance is SA, When the second sharpness value of the second noise picked up at the second sound pickup position separated from the outer surface of the second wall portion by the same second distance as the first distance is SB, the following condition is further satisfied. (3) is satisfied.
SA> SB (3)

  The user's audible impression is often affected by the sharpness value included in the noise. For example, even if the sound pressure level of noise is relatively small, the user may feel uncomfortable if the sharpness value of the noise is large. According to the above configuration, for the first and second noises, in addition to the first and second equivalent noise levels, the first and second sharpness values are also evaluated, and the sharpness value SA of the first noise is the first noise level. It is set larger than the second sharpness value SB of 2 noises. Therefore, the user's audible impression can be improved more accurately.

An image forming apparatus according to another aspect of the present invention is an apparatus main body having a housing that defines an accommodation space, and a first wall portion that defines one wall surface of the housing, and the one wall surface. A second wall portion defining another different wall surface, and an apparatus main body in which an image forming operation for forming an image on a sheet is performed in the accommodation space, and the first wall portion in the accommodation space. A drive unit that is disposed close to the drive unit that supplies a drive force necessary for the image forming operation, and is disposed close to the second wall unit in the accommodation space, and conveys the sheet in accordance with the image forming operation. A stationary sound generated when the driving unit supplies the driving force is defined as a first noise, and an unsteady sound generated when the conveying unit conveys the sheet is defined as a first noise. 2 noises away from the outer surface of the first wall by a first distance The first sharpness value of the first noise picked up at one sound pickup position is SA, and the second sound pickup position that is separated from the outer surface of the second wall portion by the same second distance as the first distance. If the second sharpness value of the second noise collected in step SB is SB, the following condition (3) is satisfied.
SA> SB (3)

  According to the above configuration, the first sharpness value SA is set larger than the second sharpness value SB. Therefore, the first noise that is a stationary sound can be generated in a state where the high-frequency component of the second noise that is an unsteady sound is suppressed. That is, the user listens to the overall noise generated by the image forming apparatus in a state in which the noise at the time of supplying the driving force, which is a steady sound, is emphasized more than the noise during sheet conveyance, which often includes impact sound become. As a result, the user's audible impression is improved, that is, the noise of the image forming apparatus is achieved.

  According to the image forming apparatus of the present invention, the second noise that is a non-stationary sound is lower than the sound pressure level and / or the sharpness value of the first noise that is a stationary sound, so that a masking effect can be easily obtained. Improvement of the user's audible impression, that is, quietness and pleasantness are achieved.

1 is an external perspective view of an image forming apparatus according to a first embodiment of the present invention as viewed obliquely from the front right. FIG. 2 is an external perspective view of the image forming apparatus as viewed from the left front side. FIG. 2 is an external perspective view of the image forming apparatus as viewed obliquely from the rear. FIG. 3 is a rear perspective view of the image forming apparatus with the back cover and the extension cover removed. 2 is a cross-sectional view illustrating an internal configuration of the image forming apparatus. FIG. It is a figure which shows the result of the experiment conducted about the equivalent noise level. It is a figure which shows the relationship between the 1st sound pressure level of a 1st noise and the 2nd sound pressure level of a 2nd noise in the comparative example 1. It is a figure which shows the relationship between the 1st sound pressure level of a 1st noise, and the 2nd sound pressure level of a 2nd noise in the comparative example 2. FIG. It is a figure which shows the relationship between the 1st sound pressure level of a 1st noise, and the 2nd sound pressure level of a 2nd noise in the comparative example 3. It is a figure which shows the relationship between the 1st sound pressure level of 1st noise and the 2nd sound pressure level of 2nd noise in Example 1. FIG. It is a fluctuation comparison of the overall value of loudness based on ISO532B, and shows the result of measuring the loudness of the second noise for each of Example 1 and Comparative Example 2. It is a graph which shows the sound pressure level acquired about Example 3 and 4 and the comparative examples 4 and 5 which concern on the image forming apparatus of 2nd Embodiment which considers a sharpness value. It is a graph which shows the sharpness value acquired about the said Examples 3 and 4, and the comparative examples 4 and 5. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is an external perspective view of the image forming apparatus 1 according to the first embodiment of the present invention as seen from the right front side. FIG. 2 is an external perspective view of the image forming apparatus 1 as viewed obliquely from the left front. FIG. 3 is an external perspective view of the image forming apparatus 1 as viewed obliquely from the rear. The image forming apparatus 1 illustrates an in-body discharge type and monochrome type multifunction peripheral. Note that terms representing directions such as “up”, “down”, “left”, “right”, “front”, and “rear” are merely for the purpose of clarifying the description, and the present invention is not limited to this. It is not intended to limit.

  The image forming apparatus 1 includes an apparatus main body 2 having a substantially rectangular parallelepiped housing structure that defines an accommodation space. In the apparatus main body 2, an image forming operation for forming an image on a sheet is performed. The apparatus main body 2 includes a substantially rectangular parallelepiped lower casing 20, a substantially rectangular parallelepiped upper casing 22 disposed above the lower casing 20, and a connection that connects the lower casing 20 and the upper casing 22. And a housing 23. The lower housing 20 accommodates various devices for image forming operations, and the upper housing 22 accommodates various devices for optically reading a document image. An in-cylinder space surrounded by the lower casing 20, the upper casing 22, and the connecting casing 23 serves as an in-cylinder discharge unit 24 that can store a sheet after image formation.

  The in-cylinder space used as the in-cylinder sheet discharge unit 24 is open to the outside on the front surface and the left side surface of the apparatus main body 2. The user can insert his / her hand through these open portions and take out the sheet after image formation from the in-body sheet discharge unit 24. A bottom surface 241 of the inner space is defined by the upper surface of the lower housing 20.

  An operation panel unit 25 protrudes from the front surface of the upper housing 22. The operation panel unit 25 includes an operation key 251 including a numeric keypad and a start key, an LCD touch panel 252 and the like, and receives input of various operation instructions from the user. The user can input the number of sheets to be printed and the like and input the print density and the like through the operation panel unit 25. On the upper housing 22, a pressing cover 226 (not shown in FIG. 2) for pressing a document from which an image is read is disposed. The presser cover 226 is attached to the upper housing 22 so as to be rotatable at the rear edge thereof.

  A paper feed cassette 211 that houses a sheet on which image forming processing is performed is mounted on the lower housing 20. The paper feed cassette 211 can be pulled out from the front surface of the lower housing 20 in the forward direction. The paper feeding cassette 211 is a cassette provided for automatic paper feeding.

  The apparatus main body 2 has a plurality of exterior covers that constitute the appearance of the image forming apparatus 1. As such an exterior cover, a front cover 21 disposed on the front side of the image forming apparatus 1, a right side cover 28 disposed on the right side of the image forming apparatus 1, and a left side of the image forming apparatus 1 are disposed. The left side cover 26 and the back cover 27 disposed on the back side of the image forming apparatus 1 are used.

  The front cover 21 is disposed between the paper feed cassette 211 and the in-body paper discharge unit 24, and constitutes the appearance of the front part of the image forming apparatus 1 together with the front surface of the paper feed cassette 211.

  The right side cover 28 is a cover member that extends in the vertical direction of the apparatus main body 2 from the lower portion of the lower housing 20 to the upper portion of the connection housing 23. The right side cover 28 is provided with a manual feed tray 35 that can be freely opened and closed. The right side cover 28 has a rear edge 28 a (FIG. 1) that extends in the vertical direction of the apparatus main body 2. The back cover 27 described later has a right edge portion 27 a (FIG. 3) extending in the vertical direction of the apparatus main body 2. The right side cover 28 and the back cover 27 are arranged so that the rear edge portion 28a and the right edge portion 27a form an angle of approximately 90 degrees with each other in the state of being close to the vertical direction of the apparatus main body 2.

  The left side cover 26 includes a lower cover 262 disposed on the left side surface portion of the lower housing 20 and an upper cover 261 disposed on the left side surface portion of the upper housing 22. An extension cover 29 is provided in a range from a portion of the left side cover 26 near the back cover 27 to a portion of the back cover 27 near the left side cover 26. The expansion cover 29 is attached to the apparatus main body 22 by snap fitting, and the user can easily remove and attach the expansion cover 29.

  FIG. 4 is a rear perspective view of the image forming apparatus 11 with the back cover 27 and the extension cover 29 removed. As shown in the figure, when the back cover 27 and the extension cover 29 are removed, a back frame 30 that constitutes a part of the framework of the apparatus main body 22 appears. The back frame 30 is a flat frame made of sheet metal. The back frame 30 is provided with a plurality of mechanisms and members that are involved in an image forming operation described later. Specifically, the rear frame 30 includes a motor 31 that supplies a driving force necessary for the image forming operation, a fan 32 for discharging heat generated in the apparatus main body 22 to the outside, and a main unit that controls the image forming operation. A controller box 33 for accommodating a control board and the like, a gear box 35 for accommodating a gear group for transmitting the driving force of the motor 31, and the like are disposed. The controller box 33 is provided with a fan 34 for discharging the heat generated in the controller box 33. Hereinafter, the motor 31, the gear group of the gear box 35, the fans 32 and 34, and the like are collectively referred to as a drive unit for convenience.

  As described above, since the drive unit is disposed close to the inner surface of the back cover 27, the back cover 27 side is called a drive surface. When an image forming operation is started in the apparatus main body 2, noise generated in the drive unit leaks to the outer surface side of the back cover 27 via the back cover 27, that is, from the drive surface to an external environment where the user is active. Leak. Noise generated in the drive unit (hereinafter referred to as first noise) is a steady sound that is repeated at a constant period in accordance with the image forming operation. The back cover 27 is an example of the first wall portion of the present invention, and the inner surface and the outer surface of the back cover 27 are an example of the wall surface 1 of the present invention.

  Next, an image forming operation performed in the apparatus main body 2 will be described with reference to FIG. FIG. 5 is a cross-sectional view showing an internal configuration of the image forming apparatus 1. In the housing space of the apparatus main body 22, an image forming unit 40, a fixing unit 50, and a conveying unit 60 are disposed.

  The image forming unit 40 transfers an image onto a sheet supplied from the paper feed cassette 211 and forms an image on the sheet. The image forming unit 40 includes a photosensitive drum 41 that carries an electrostatic latent image, a charging unit 42 that charges the surface of the photosensitive drum 41, and a laser beam that transmits an electrostatic latent image corresponding to a document image to the surface of the photosensitive drum 41. The exposure unit 43 is formed by, for example, a developing unit 44 that forms an image by attaching a developer to the formed electrostatic latent image, the transfer roller 45 that transfers the image to a sheet, and the surface of the photosensitive drum 41 after the image transfer. A neutralizing unit 46 for neutralizing, a cleaning blade 47 for removing residual toner on the surface of the photosensitive drum 41, and the like are included.

  The fixing unit 50 fixes the image transferred on the sheet onto the sheet. The fixing unit 50 includes a fixing roller 51 having an energized heating element therein, and a pressure roller 52 disposed to face the fixing roller 51. The image on the sheet is heated and fixed on the sheet when passing through the nip portion between the fixing roller 51 and the pressure roller 52. An operation performed in the apparatus main body 2 including an image forming operation by the image forming unit 40 and an image fixing operation by the fixing unit 50 is referred to as an image forming operation.

  The transport unit 60 transports the sheets in the paper feed cassette 211 in the order of the image forming unit 40, the fixing unit 50, and the in-body discharge unit 24 in accordance with the image forming operation. It is arrange | positioned adjacent to. The conveyance unit 60 includes a conveyance path 70 that extends in the vertical direction of the apparatus main body 2 in the order of the image forming unit 40, the fixing unit 50, and the in-body sheet discharge unit 24, and a group of rollers disposed along the conveyance path 70. .

  The roller group includes a pickup roller 61, a pair of paper feed rollers 62 and a separation roller 63, a pair of registration rollers 64, and a pair of first discharge rollers 65 disposed from the upstream side to the downstream side in the sheet conveyance direction. And a pair of second discharge rollers 66.

  The pickup roller 61 takes out the sheet from the placement plate 212 of the paper feed cassette 211. The sheet feeding roller 62 conveys the sheet toward the pair of registration rollers 64, and the separation roller 63 prevents the sheets from being double-fed. The pair of registration rollers 64 convey the sheet at an appropriate timing toward the nip portion between the photosensitive drum 41 and the transfer roller 45 while correcting the oblique feeding of the sheet. The pair of first discharge rollers 65 and the pair of second discharge rollers 66 convey the sheet subjected to the fixing process toward the in-body discharge unit 24.

  The conveyance path 70 is defined by a plurality of guide members. As the guide members, for example, a first guide member 71, a pair of second guide members 72, a pair of third guide members 73, a pair of fourth guide members 74, and a pair of fifth guide members 75 are used.

  The first guide member 71 is for guiding the sheet to the nip portion between the sheet feeding roller 62 and the separation roller 63, and is disposed immediately upstream of the nip portion as viewed from the sheet conveying direction. . The pair of second guide members 72 are for guiding the sheet conveyed by the sheet feeding roller 62 to the pair of registration rollers 64, and are located immediately downstream of the sheet feeding roller 62 when viewed from the sheet conveying direction. It is arranged.

  The pair of third guide members 73 defines the angle of entry of the sheet with respect to the nip portion between the pair of registration rollers 64, and guides the sheet to the nip portion, as viewed from the sheet conveying direction. It is disposed immediately upstream of the nip portion. The pair of fourth guide members 74 extends between the nip portion between the pair of registration rollers 64 and the transfer nip portion between the photosensitive drum 41 and the transfer roller 45 and is conveyed from the pair of registration rollers 64. Is guided to the transfer nip.

  The pair of fifth guide members 75 extends between the pair of first discharge rollers 65 and the pair of second discharge rollers 66, and the pair of second discharge rollers 66 conveys the sheet conveyed by the pair of first discharge rollers 65. To guide.

  Thus, since the conveyance part 60 is provided close to the inner surface of the right side cover 28, the right side cover 28 side is called a conveyance surface. When the image forming operation is started in the apparatus main body 2, the conveying unit 60 starts conveying the sheet. As the sheet is conveyed, noise is generated in the conveying unit 60. Noise generated in the transport unit 60 leaks to the outer surface side of the right side cover 28 via the right side cover 28, that is, leaks from the transport surface to the external environment where the user is active.

  An example of noise generated in the conveyance unit 60 is an impact sound caused by a sheet. During the conveyance of the sheet, the leading end and the trailing end in the conveyance direction of the sheet collide with a guide member that defines the conveyance path 70. Therefore, an impact sound is generated.

  Noise generated in the transport unit 60 (hereinafter referred to as second noise) is not a steady sound that is repeated at a constant period in accordance with the image forming operation, and does not have a constant period. It is an unsteady sound that varies irregularly and greatly over time. The right side cover 28 is an example of the second wall portion of the present invention, and the inner surface and the outer surface of the right side cover 28 are examples of other wall surfaces of the present invention.

Since the second noise generated in the transport unit 60 is an unsteady sound, it is very uncomfortable for the user. In order to reduce the noise of the image forming apparatus 1 and make the image forming apparatus 1 easy to use for the user, in the present embodiment, the image forming apparatus 1 is configured to satisfy the following conditional expression (1). .
LA> LB (1)

  LA represents a first equivalent noise level value of the first noise generated in the drive unit, and LB represents a second equivalent noise level value of the second noise generated in the transport unit 60.

  The first equivalent noise level value LA is a time average value calculated by measuring the noise level of the first noise for 10 seconds at the first sound collection position on the back cover 27 side (FIG. 3). The first sound collection position is a position away from the substantially central position in the left-right direction on the outer surface of the back surface of the image forming apparatus 1 by a predetermined first distance.

  The second equivalent noise level value LB is a time average value calculated by measuring the noise level of the second noise for 10 seconds at the second sound collection position (FIG. 1) on the right side cover 28 side. The second sound collection position is an outer surface of the right side surface portion of the image forming apparatus 1 and is a position away from the substantially central position in the left-right direction of the right side surface portion when the right side surface portion is the front surface by a predetermined second distance. The second distance is the same size as the first distance. In the present embodiment, the first distance and the second distance are 50 cm. The noise level generally indicates an A characteristic frequency weighted sound pressure level.

  In order to satisfy the conditional expression (1), in this embodiment, the transport unit 60 is improved so that the noise level of the second noise generated in the transport unit 60 is lowered. Specifically, the guide member is improved in order to reduce the impact sound generated when the sheet collides with the guide member or the registration roller 64.

  For example, the shape of the first guide member 71 is changed so that the rear end portion in the sheet conveyance direction does not collide violently with the first guide member 71 when the sheet passes through the nip portion between the sheet feeding roller 62 and the separation roller 63. is doing. In addition, the shape of the pair of second guide members 72 is changed so that the trailing end portion in the conveyance direction of the sheet that has passed through the nip portion between the sheet feeding roller 62 and the separation roller 63 does not collide violently with the pair of second guide members 72. is doing.

  Further, when the sheet is guided to the nip portion between the pair of registration rollers 64, in order to suppress the impact sound generated when the front end of the sheet in the conveyance direction comes into contact with one of the registration rollers 64, a pair of third rollers The shape of the guide member 73 is improved to change the entrance angle of the sheet with respect to the nip portion. Further, by improving the shape of the pair of fourth guide members 74 that guide the sheet to the transfer nip portion between the photosensitive drum 41 and the transfer roller 45, and changing the angle of entry of the sheet into the transfer nip portion, the sheet It is suppressed that the front-end | tip part of a conveyance direction collides with a pair of 4th guide member 74 intensely.

  Further, the shapes of the pair of fifth guide members 75 are changed so that the leading ends in the conveyance direction of the sheet that has passed through the pair of first discharge rollers do not collide violently with the pair of fifth guide members 75.

  FIG. 6 shows the results of an experiment conducted on the equivalent noise level. In the experiment, Comparative Examples 1 to 3 in which the conveyance unit 60 was not improved and Example 1 in which the above-described improvement of the conveyance unit 60 was performed were used. In the experiment, not only the first equivalent noise level value of the first noise and the second equivalent noise level value of the second noise, but also the equivalent noise level value of the noise leaking from the front surface and the equivalent noise level of the noise leaking from the left side surface. Values were also measured. In Comparative Example 1, the right side surface is the transport surface, and in Comparative Examples 2 and 3, the left side surface is the transport surface. That is, in Comparative Example 1, the second equivalent noise level value of the second noise was measured on the right side, and in Comparative Examples 2 and 3, the second equivalent noise level value of the second noise was measured on the left side. Ppm represents the number of printed sheets per minute.

  As shown in FIG. 6, in Comparative Examples 1 to 3, since the transport unit 60 was not improved, the first equivalent noise level value LA of the first noise is higher than the second equivalent noise level value LB of the second noise. And LA> LB which is the conditional expression (1) is not satisfied.

  On the other hand, in the first embodiment, since the above-described transport unit 60 has been improved, the first equivalent noise level value LA of the first noise is larger than the second equivalent noise level value LB of the second noise, and the conditional expression (1) is satisfied. In addition, it was confirmed that the equivalent noise level value on the front side and the equivalent noise level value on the left side were lower than those in Comparative Examples 1 to 3 by satisfying conditional expression (1).

FIGS. 7 to 10 show a 1/3 octave band spectrum analysis in which the obtained frequency characteristics are divided by 1/3 octave bands from the FFT analysis results, and the spectrum of each band is expressed by F (flat) characteristics. The relationship between the first sound pressure level of the first noise and the second sound pressure level of the second noise is shown, the vertical axis represents the sound pressure level (dB), and the horizontal axis represents the frequency (Hz). 7 to 9 correspond to Comparative Examples 1 to 3, respectively, and FIG. 10 corresponds to Example 1. As is apparent from FIGS. 7 to 9, in Comparative Examples 1 to 3, the first sound pressure level is lower than the second sound pressure level in the 1 kHz frequency band. In contrast, in the first embodiment, the first sound pressure level is higher than the second sound pressure level in the 1 kHz frequency band.

In the present embodiment, the first sound is improved in the frequency band of 630 Hz to 3 kHz including 1 kHz that is physiologically and psychologically unpleasant for humans (unpleasant for users) by improving the transport unit 60 as described above. The following conditional expression (2) in which the pressure level is higher than the second sound pressure level is satisfied.
DA> DB (2)
DA represents the first sound pressure level of the first noise, and DB represents the second sound pressure level of the second noise.

  FIG. 11 is a comparison of fluctuations in the overall value of loudness based on ISO532B, and shows the results of measuring the loudness of the second noise for each of Example 1 and Comparative Example 2. In FIG. 11, the vertical axis represents loudness and the horizontal axis represents the number of sample points. As shown in the figure, it was confirmed that the loudness of the second noise of Example 1 was lower than the loudness of the second noise of Comparative Example 2 in all the sample points.

  Further, as shown in FIG. 6, the auditory impression of Example 1 that satisfies the conditional expressions (1) and (2) is compared with the auditory impression of Comparative Examples 1 to 3 that do not satisfy the conditional expressions (1) and (2). It was confirmed that it was good. The auditory impression was evaluated by a paired comparison method.

  In the image forming apparatus 1 according to the first embodiment described above, in the driving unit, a useful sound source effective for the mask is arranged on the transport unit 60 side, whereby the first equivalent of the first noise generated in the driving unit. The noise level value LA is set to be larger than the second equivalent noise level value LB of the second noise generated in the transport unit 60 (conditional expression (1)). Therefore, the second noise that is a non-stationary sound is easily masked by the first noise that is a stationary sound. That is, in this embodiment, the first noise is used as a masking sound. Accordingly, the user listens to the entire noise generated by the image forming apparatus 1 in a state where the first noise that is a stationary sound is emphasized more than the second noise that is an unsteady sound (a state in which a mask effect is obtained). It will be. As a result, the user's audible impression is improved, that is, the noise of the image forming apparatus 1 is achieved.

  In the present embodiment, the first sound pressure level DA of the first noise is set to be larger than the second sound pressure level DB of the second noise in the 1 kHz frequency band that is particularly disturbing for the user (conditional expression). (2)). Therefore, the user's audible impression can be improved.

  Furthermore, in the present embodiment, the second noise generated in the transport unit 60, particularly the impact sound that is an unsteady sound generated due to the collision with the guide member or the registration roller 64 during sheet transport, Since it is suppressed by improving the first guide member 71 to the fifth guide member 75, it is easily masked by the first noise.

  Furthermore, in the present embodiment, the back cover 27 in which the drive unit is disposed close to the right side cover 28 in which the transport unit 60 is disposed in close proximity is disposed at an angle of approximately 90 degrees. Therefore, the effect of masking the second noise by the first noise can be easily obtained.

  As is apparent from the above description, the image forming apparatus 1 according to the first embodiment includes an evaluation unit that generalizes the user's impression evaluation by further satisfying the conditional expression (1), preferably the conditional expression (2). It is to provide.

[Second Embodiment]
Next, an image forming apparatus according to the second embodiment will be described in which the sharpness value is added or the sharpness value is mainly considered for the first noise generated in the drive unit and the second noise generated in the transport unit 60. . The configuration of the image forming apparatus is basically the same as the configuration of the image forming apparatus 1 described above with reference to FIGS.

  The sharpness value is an index indicating the sharpness of sound, and the sharpness value becomes higher as more sharp high-frequency sounds that are annoying to noise are included. The sharpness value is roughly determined by the ratio of the energy amount of the high frequency sound to the total energy amount of the sound. Specifically, the back cover 27 side is obtained by numerically analyzing the collected sound data acquired for calculating the first equivalent noise level value LA and the second equivalent noise level value LB used in the first embodiment. In addition, the sharpness value on the right side cover 28 side can be obtained. In practice, the numerical analysis can be executed using commercially available sound quality evaluation software compliant with ISO532B.

In the second embodiment, the first sharpness value of the first noise collected at the first sound collection position separated from the outer surface of the back cover 27 (first wall portion) by the first distance is SA, and the right side cover 28 is used. When the second sharpness value of the second noise picked up at the second sound pickup position separated from the outer surface of the (second wall portion) by the same second distance as the first distance is SB, the following condition ( The image forming apparatus is configured to satisfy 3).
SA> SB (3)

  The first sharpness value SA is obtained by using commercially available sound quality evaluation software based on the above-mentioned ISO 532B for the first noise data obtained by measuring for 10 seconds at the first sound collection position (FIG. 3) on the back cover 27 side. It is a value obtained by analyzing. The second sharpness value SA is obtained by using commercially available sound quality evaluation software based on the above-mentioned ISO 532B based on the second noise data obtained by measuring for 10 seconds at the second sound collection position (FIG. 1) on the right side cover 28 side. It is a value obtained by using and analyzing. Note that the first distance and the second distance are also 50 cm in this second embodiment.

  The user's audible impression is often affected by the sharpness value included in the noise. Although noise generated by the sheet is included in the noise generated in the conveyance unit 60, the high-frequency component is dominant in such impact noise. That is, it is noise with a high sharpness value, and is generally noise that many users feel uncomfortable. Even if the sound pressure level of the noise itself is relatively small, the user may feel uncomfortable if the sharpness value of the noise is large. Accordingly, not only the conditional expression (1) related to the first and second equivalent noise levels mentioned in the first embodiment or the conditional expression (2) related to the first and second sound pressure levels is satisfied, but the first and second It is desirable that the image forming apparatus satisfy the conditional expression (3) regarding the 2 sharpness value. Alternatively, it is desirable that the image forming apparatus satisfy at least the conditional expression (3).

  In such an image forming apparatus, the first sharpness value SA is set larger than the second sharpness value SB. Therefore, it is possible to generate the first noise, which is a stationary sound, which is emitted from the drive unit in a state where the high-frequency component of the second noise, which is an unsteady sound, which is emitted from the transport unit 60 is suppressed. In other words, the user listens to the overall noise generated by the image forming apparatus in a state where the noise at the time of supplying the driving force, which is a steady sound, is emphasized more than the impulsive sound generated by sheet conveyance. Thereby, the annoying feature of the impact sound can be improved by the driving sound in the high frequency range. As a result, the user's audible impression is improved, that is, the noise of the image forming apparatus is achieved.

  In order to satisfy both of the conditional expressions (1) to (2) and the conditional expression (3), or to satisfy at least the conditional expression (3), the device to be given to the conveying unit 60 of the image forming apparatus is described above. This is basically the same as the first embodiment. For example, in order to reduce the impact sound generated when the sheet collides with the guide member or the registration roller 64, the material and shape of the second, third, fourth, and fifth guide members 72, 73, 74, and 75 are changed. An improvement (contact angle adjustment) is provided to the image forming apparatus that improves and reduces the impact of the sheet colliding with the guide member and the registration roller 64.

  12 and 13 show the results of experiments conducted for both the equivalent noise level [dB] and the sharpness value [acum]. In the experiment, the image forming apparatus according to Examples 2 and 3 in which the above-described improvement was performed on the conveyance unit 60 and the image forming apparatus according to Comparative Examples 4 and 5 in which no special improvement was performed on the conveyance unit 60 are used. It was. In the experiment, not only the first and second equivalent noise level values and the first and second sharpness values for the first and second noises, but also the equivalent noise level value and sharpness value of noise leaking from the front surface, and the left side surface. The equivalent noise level value and the sharpness value of the noise leaking from were also measured. 12 and 13, ppm indicates the number of printed sheets per minute.

  As shown in FIG. 12, in Comparative Examples 4 and 5, since the transport unit 60 was not improved, the first equivalent noise level value LA of the first noise is higher than the second equivalent noise level value LB of the second noise. And LA> LB in the conditional expression (1) is not satisfied. Further, as shown in FIG. 13, the second noise sharpness value SB is larger than the first noise sharpness value SA, and SA> SB of the conditional expression (3) is not satisfied.

  On the other hand, in Examples 2 and 3, since the improvement of the transport unit 60 described above was performed, the first equivalent noise level value LA of the first noise is larger than the second equivalent noise level value LB of the second noise, Conditional expression (1) is satisfied. Further, the second sharpness value SB of the second noise is suppressed more than the sharpness value SA of the first noise, and SA> SB of the conditional expression (3) is also satisfied.

  For such image forming apparatuses according to Examples 2 and 3 and image forming apparatuses according to Comparative Examples 4 and 5, the auditory impression was evaluated by a paired comparison method. As a result, it was confirmed that the auditory impressions of Examples 2 and 3 satisfying conditional expressions (1) and (3) were better than those of Comparative Examples 4 and 5 that did not satisfy conditional expressions (1) and (3). It was done.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 21 Front cover 26 Left side cover 27 Back cover (1st wall part)
28 Right side cover (second wall)
30 Rear frame 31 Motor 32 Fan 33 Controller box 35 Gear box 40 Image forming unit 50 Fixing unit 60 Conveying unit 70 Conveying path 71 First guide member 72 Second guide member 73 Third guide member 74 Fourth guide member 75 Fifth guide Member P1 First sound collection position P2 Second sound collection position

Claims (6)

An apparatus main body having a housing that defines an accommodation space, and a first wall portion that defines one wall surface of the housing, and a second wall portion that defines another wall surface different from the one wall surface. An apparatus main body in which an image forming operation for forming an image on a sheet is performed in the accommodation space;
A drive unit that is disposed in the housing space in proximity to the first wall and supplies a drive force necessary for the image forming operation;
A conveying unit disposed in the housing space in proximity to the second wall and conveying the sheet in accordance with the image forming operation;
With
A stationary noise generated when the driving unit supplies the driving force is a first noise,
The unsteady sound generated when the transport unit transports the sheet is defined as second noise.
The first equivalent noise level value of the first noise collected at the first sound collection position separated from the outer surface of the first wall by a first distance is defined as LA,
When the second equivalent noise level value of the second noise picked up at the second sound pickup position separated from the outer surface of the second wall portion by the same second distance as the first distance is LB,
An image forming apparatus that satisfies the following condition (1).
LA> LB (1) The image forming apparatus according to claim 1.
The first sound pressure level of the first noise is DA,
When the second sound pressure level of the second noise is DB,
An image forming apparatus that satisfies the following condition (2) in a frequency band around 1 kHz.
DA> DB (2) The image forming apparatus according to claim 2.
The transport unit includes a guide member for transporting the sheet, and a transport path defined by the guide member,
The non-stationary sound includes an impact sound generated when the sheet collides with the guide member when the sheet is conveyed along the conveyance path. The image forming apparatus according to claim 1,
The first wall has a first edge extending in the vertical direction of the apparatus main body,
The second wall portion extends in the up-down direction of the apparatus main body, has a second edge portion in a state of being close to the first edge portion, and is disposed substantially orthogonal to the first wall portion. Image forming apparatus. In the image forming apparatus according to any one of claims 1 to 4,
SA is a first sharpness value of the first noise collected at a first sound collection position separated from the outer surface of the first wall by a first distance;
When the second sharpness value of the second noise picked up at the second sound pickup position separated from the outer surface of the second wall portion by the same second distance as the first distance is SB,
Furthermore, an image forming apparatus that satisfies the following condition (3).
SA> SB (3) An apparatus main body having a housing that defines an accommodation space, and a first wall portion that defines one wall surface of the housing, and a second wall portion that defines another wall surface different from the one wall surface. An apparatus main body in which an image forming operation for forming an image on a sheet is performed in the accommodation space;
A drive unit that is disposed in the housing space in proximity to the first wall and supplies a drive force necessary for the image forming operation;
A conveying unit disposed in the housing space in proximity to the second wall and conveying the sheet in accordance with the image forming operation;
With
A stationary noise generated when the driving unit supplies the driving force is a first noise,
The unsteady sound generated when the transport unit transports the sheet is defined as second noise.
SA is a first sharpness value of the first noise collected at a first sound collection position separated from the outer surface of the first wall by a first distance;
When the second sharpness value of the second noise picked up at the second sound pickup position separated from the outer surface of the second wall portion by the same second distance as the first distance is SB,
An image forming apparatus that satisfies the following condition (3).
SA> SB (3)

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