JP2005345606A - Image forming apparatus, image forming apparatus manufacturing method, image forming apparatus modifying method, and tone quality evaluation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contribute to improvement in use environment by reducing unpleasant sound emitted from an image forming apparatus. <P>SOLUTION: A psychoacoustic parameter value is lowered by modifying a source of unpleasant sound so that the sound pressure level value, loudness value, sharpness value, tonality value, and impulsiveness value of acoustic physical quantity obtained from sound emitted from the image forming apparatus when image formation is carried out on an image formation sheet, which is collected in a sound collecting position 1m away from the end face of the image forming apparatus, and a probability P calculated using the output value (ppm) of the image formation sheet (A4-size in lateral direction) per minute, satisfy prescribed conditions. This realizes the image forming apparatus in which the psychoacoustic parameter is not higher than a tone quality evaluation value permissible for users. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, a manufacturing method of the image forming apparatus, a remodeling method of the image forming apparatus, and a sound quality evaluation method. Specifically, the present invention relates to a method for improving unpleasant sound generated by a complicated operation mode of the image forming apparatus. It is suitable for application to general office automation equipment, printers, home appliances and the like.

  In recent years, from the viewpoint of environmental friendliness, interest in noise problems has increased, and there are many requests for solving noise problems for office automation equipment in offices. Therefore, the noise reduction of OA equipment is being promoted.

  As a technique for solving the above-described noise problem, for example, Patent Document 1 relates to a noise masking device such as a laser beam printer or a copying machine. A sounding body that generates a masking sound for masking noise, and a masking sound control means that controls the sounding body and generates a masking sound having a frequency in a range including the main component frequency of the noise. A technique for reducing the above is disclosed.

  However, the technique disclosed in Patent Document 1 does not reduce the generated sound, but adds a masking sound to the generated sound, resulting in a drawback that the noise level increases. In addition, a sound generator for generating a masking sound and a control device and a speaker for generating a masking sound only during the generation time of the masked sound are required. In addition, there is a drawback that the cost is significantly increased.

In addition to the techniques described in the above patent documents, the following sound quality evaluation apparatus and sound quality evaluation method have been proposed.
Patent Document 2 relates to a sound quality evaluation device, a sound quality evaluation method, and a sound quality evaluation device. Low-frequency random noise generated in an air flow system such as exhaust sound from noise composed of many timbre sounds of an image forming apparatus. This makes it possible to evaluate only “go sound”, which is a serious noise, and facilitates the correspondence with psychological annoyance.

  Patent Document 3 relates to a sound quality evaluation method and a sound quality evaluation apparatus, which are recognized as harsh sounds from noises composed of many timbre sounds of an image forming apparatus and are sustained by a scanner motor or a charging device. Only the “keen sound”, which is a pure tone, is extracted and evaluated.

  Patent Document 4 relates to a sound quality evaluation method and a sound quality evaluation apparatus, and only “shear noise”, which is high-frequency random noise due to paper rubbing, in particular, from noise composed of many timbre sounds of an image forming apparatus. It is extracted and evaluated.

  Patent Document 5 relates to a sound quality evaluation method and a sound quality evaluation apparatus. From noise composed of many timbre sounds of an image forming apparatus, particularly from a pure sound having peaks at a plurality of adjacent frequencies due to a drive system beat. The “Won-won sound” is extracted and evaluated.

  Patent Document 6 relates to a sound quality evaluation method and a sound quality evaluation apparatus, and in noise composed of many timbre sounds of an image forming apparatus, there is no pure tone or beat, that is, no component protruding in a frequency waveform. Since it feels smooth, the annoyance that people feel is generically called “smoothness”, and the smoothness of the sound is extracted and evaluated.

  Patent Document 7 relates to a sound quality evaluation apparatus and a sound quality evaluation method, and performs a plurality of sound indexes after performing preprocessing necessary for calculation of various sound indexes on a digital signal of a sound to be evaluated. To do. At this time, not only the sound volume index is calculated, but also the high frequency pure tone index and the broadband noise index are calculated in consideration of the influence of noise on the subjective annoyance and discomfort. Then, an overall sound quality index is calculated based on the obtained magnitude index, high frequency pure tone index, and broadband noise index, and the calculation result is displayed. As a result, it is possible to evaluate the overall sound quality in consideration of the influence on the subjective sense of the person, such as noise generated from office equipment.

  These series of prior arts are a sound quality evaluation device and a sound quality evaluation method, and only a sound quality evaluation method is presented, and a sound quality improvement method or a device for improving sound quality of an actual product is not mentioned.

Patent Document 8 relates to an image forming apparatus and a sound quality improvement method, and a sheet by a conveyance mechanism in a sheet guide path that guides a sheet to a predetermined path via an image forming unit that forms an image on the sheet. During transport, the operating sound discomfort index S acquired based on the loudness value A and sharpness value B of the operating sound generated from the apparatus main body measured at a position 1 m away from the apparatus main body,
S = 0.01024269 × A ² + 0.30996744 × B−2.1386517
S <−0.3555
The paper conveying means has been improved so that it is set within the range to reduce psychological discomfort caused by sounds generated by the apparatus around the apparatus.

At present, various apparatuses equipped with image forming apparatuses such as copying machines, printers, and facsimile machines are installed in offices and the like. In this type of image forming apparatus, many parts are mechanically connected.
In addition, the image forming apparatus has a motor for driving these mechanisms and the like, and during the image forming operation, an operation sound of each part of the apparatus is generated, and this operation sound causes discomfort to the user. It can be a problem. In the past, these devices only have to be convenient. However, as the environment in the office has improved, there has been an increasing demand for solving noise problems for OA devices. The noise reduction has been promoted, and a considerable noise reduction has been achieved compared to before.

  Currently, an image forming apparatus generally uses a sound power level or a sound pressure level (ISO 7779) as a method for evaluating noise. However, since these are values of acoustic energy generated from office equipment such as copying machines and printers, the correlation with human subjective discomfort with noise may not be very good.

For example, when listening to sounds with the same sound pressure level (equivalent noise level Leq: energy averaged over the entire measurement time), the difference in discomfort may vary depending on the difference in sound frequency distribution or the presence or absence of impact sound. There may be.
Moreover, even if the value of the sound pressure level is small, it may be uncomfortable if a high frequency component, a pure sound component, or the like is included.

Therefore, in order to improve the office environment in the future, it is necessary not only to evaluate and reduce the sound power level and sound pressure level of OA equipment, but also to simultaneously evaluate and improve sound quality.
In order to evaluate and improve the sound quality, it is necessary to measure the sound quality quantitatively for the purpose of grasping the current situation and how much it has been improved before and after the improvement, but since the sound quality is not a physical quantity, it is quantitative. Measurement cannot be performed, and setting of a target value is difficult.

In the case of human sound quality evaluation, qualitative expressions such as “sound quality has been improved a little” or “substantially improved” are used. Furthermore, because of individual differences, it may be difficult to determine whether the evaluation differs from person to person or whether the obtained results can be generally said. If the sound quality cannot be expressed quantitatively with physical characteristics, objective evaluation of countermeasures is impossible.
For this reason, it is necessary to perform subjective evaluation experiments and perform statistical processing on the results to quantify sound quality.

  By the way, as a physical quantity for evaluating sound quality, there is a psychoacoustic parameter. Typical ones are as follows (units in parentheses). (For example, see Non-Patent Document 1)

・ Loudness (sone): loudness ・ Sharpness (acum): relative distribution of high frequency components ・ Tonality (tu): relative distribution of articulation and pure tone components ・ Roughness (asper): coarse sound Feeling ・ Fractation strength (vacil): Fluctuation strength, groaning, and others ・ Impulse (iu): Impact ・ Relative approach: Fluctuation

A device that can measure the psychoacoustic parameters has come out. As any parameter increases, discomfort tends to increase.
Among them, only loudness is standardized by ISO532B, but the basic concept and definition of other parameters are the same, but the program and calculation method differ depending on the original research by the instrument manufacturer. Usually, the measured values differ slightly depending on the manufacturer.
There are also original parameters developed by instrument manufacturers, such as impulsiveness and relative approach.
JP 09-193506 A JP-A-10-232163 Japanese Patent Laid-Open No. 10-253440 Japanese Patent Laid-Open No. 10-253442 JP-A-10-267742 Japanese Patent Laid-Open No. 10-267743 JP 2001-336975 A JP 2002-128316 A The Japan Society of Mechanical Engineers "7th Design Engineering and System Division Lecture" Aiming for an innovative leap in design and systems for the 21st century! "" November 10th and 11th, 1997 "Sound / Vibration and Design, Color and Design (1)" Section 089B

  By the way, noise generated from office automation equipment such as copiers and printers is composed of many timbre noises due to the complexity of the mechanism. For example, low-frequency heavy sounds, high-frequency high-pitched sounds, and shock noise are generated. Sound or the like is generated while changing in time from a plurality of sound sources such as a motor, paper, and solenoid.

  Although humans judge these sounds comprehensively to determine whether they are uncomfortable, it is considered that they are determined by weighting which part of the sound is particularly related to discomfort. That is, there are psychoacoustic parameters that have a large influence on discomfort due to the timbre of the machine and psychoacoustic parameters that have a small influence.

  By the way, there are various types of image forming apparatuses, such as a small low-speed machine installed on a desk, a medium-sized medium-speed machine installed on the desk side, or a large machine installed slightly away from the desk on the office floor. There is a high-speed machine. Further, there may be a case where the mode can be set depending on the resolution of the image, the color or monochrome image, and the thickness or material of the sheet member that outputs the image on a single machine. In this case, the image forming speed and the operating part of the machine may be different in one machine.

These are used in various ways depending on the size of the office and the needs of the user. The structure strength, the mechanical configuration, and the image forming process conditions differ depending on the machine, and the operating sound characteristics vary depending on the machine.
Further, in the case of an image forming apparatus having a plurality of modes in one unit, there are a plurality of image forming speeds depending on the selected mode, and a part that operates inside the image forming apparatus differs, so that a plurality of different operating sounds are generated depending on the mode. There is a case. That is, it is conceivable that the impression of the operating sound varies depending on the type of the image forming apparatus, and the uncomfortable sound source varies.

  In one machine, when the image forming mode is changed, the rotational speed of the drive system is changed, the generated frequency is changed, and the number of times the impact sound is generated per unit time is changed. In addition, the sound that is generated varies depending on the part that operates. In other words, the impression of the operating sound varies depending on the mode, and the sound source that feels uncomfortable varies.

  Therefore, there are various types of image forming apparatuses and a plurality of operation modes. When different sounds are generated depending on the modes, it is not sufficient to use a single apparatus or a single mode sound quality evaluation alone to improve sound quality. Yes, it is necessary to evaluate the sound quality for each device and mode.

  Sound quality evaluation of multiple image forming devices and image forming devices with multiple image forming modes is performed for each device and mode, and the results are comprehensively analyzed to derive a single sound quality evaluation formula to improve unpleasant sound sources. Thus, the problem of unpleasant sound in the office is solved by lowering the psychoacoustic parameter value and providing an image forming apparatus having a sound quality evaluation value or less that is acceptable to the user.

  The present invention has been made in consideration of the above-described circumstances, and is an image forming apparatus that relaxes psychological discomfort by improving the unpleasant sound source of the image forming apparatus, a method for manufacturing the image forming apparatus, and image formation An object is to provide a method for modifying a device and a method for evaluating sound quality.

  In order to solve the above problem, the invention according to claim 1 is an image forming apparatus for forming an image on an image forming target sheet, and the sound is picked up at a sound collecting position 1 m away from an end surface of the image forming apparatus. A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from sound generated by the image forming apparatus when image formation is performed on the image forming target sheet; The following formula (a) using the output numerical value (ppm) of the image forming target sheet (A4 size lateral direction) per minute

The probability P calculated by the following condition (b)

It is characterized by satisfying.

  According to a second aspect of the present invention, there is provided an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target sheet is picked up at a sound collecting position 1 m away from an end surface of the image forming apparatus. The sound pressure level value, the loudness value, the sharpness value, the tonality value, the impulsiveness value of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus during image formation, and the image forming target sheet per minute ( The following formula (d) using the output numerical value (ppm) of (A4 size lateral direction)

The probability P calculated by the following condition (b)

It is characterized by satisfying.

  According to a third aspect of the present invention, there is provided an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target sheet is picked up at a sound collecting position 1 m away from an end surface of the image forming apparatus. The sound pressure level value, the loudness value, the sharpness value, the tonality value, the impulsiveness value of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus when the image is formed, and the image forming speed for the image forming target sheet ( v: mm / s) and the following formula (a)

The probability P calculated by the following condition (e)

It is characterized by satisfying.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target sheet is picked up at a sound collecting position 1 m away from an end surface of the image forming apparatus. The sound pressure level value, the loudness value, the sharpness value, the tonality value, the impulsiveness value of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus during image formation, and the image forming target sheet per minute ( The following formula (d) using the output numerical value (ppm) of (A4 size lateral direction)

The probability P calculated by the following condition (e)

It is characterized by satisfying.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the image formation is performed in a plurality of image forming apparatuses having different image forming speeds or driving units or operations of the image forming means. The probability P satisfies the above condition regardless of the speed and the image forming mode.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the sound collection position is a neighbor position defined in ISO (International Organization For Standardization) 7779, The probability P calculated from at least the sound collection result of the sound in the front direction of the apparatus (surface having the operation unit) satisfies the condition.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, An average value of the probabilities P calculated from the sound collection results of four directions of sound in the front, rear, left and right of the apparatus satisfies the condition.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the sound collection position is a neighbor position defined in ISO (International Organization For Standardization) 7779, The probability P calculated from the sound collection result of sound in any one direction of at least the front, rear, left and right of the apparatus satisfies the condition.

  According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, All the probabilities P calculated from the sound collection results of the sound in the four directions, front, back, left, and right of the device satisfy the condition.

  According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, the image forming apparatus further includes a reduction unit that reduces a sound generated by the apparatus when an image is formed on the image forming target sheet. Features.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, a stepping motor that drives a predetermined portion during image formation on the image forming target sheet, and a bracket member that holds the stepping motor. Further, the pure sound component reducing means includes an elastic body disposed between the stepping motor and the bracket member.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to the tenth aspect of the present invention, the image forming apparatus further includes a stepping motor that drives a predetermined portion during image formation on the image formation target sheet, Drive control means for driving the stepping motor by microsteps is provided.

  A thirteenth aspect of the present invention is the image forming apparatus according to the tenth aspect of the present invention, further comprising a motor that drives a predetermined portion during image formation on the image forming target sheet, wherein the reducing means is in the vicinity of the motor. It has the Helmholtz resonator arrange | positioned in this.

  A fourteenth aspect of the present invention is the image forming apparatus according to the tenth aspect, further comprising: a cylindrical image carrier having a hollow portion; and a charging unit that charges the surface of the image carrier. The reducing means has a damping member that suppresses vibration of the image carrier in the hollow portion of the image carrier.

  According to a fifteenth aspect of the present invention, in the image forming apparatus according to the tenth aspect, the image forming apparatus is a guide member made of a flexible sheet that guides the image forming target sheet along a predetermined conveyance path, and is conveyed. The image forming apparatus further includes a guide member in which an end portion in contact with the image forming target sheet is a bent portion of the flexible sheet.

  According to a sixteenth aspect of the present invention, in the image forming apparatus according to the tenth aspect, the toner used for image formation on the image forming target sheet is a toner containing wax.

  According to a seventeenth aspect of the present invention, in the image forming apparatus according to the tenth aspect, the impact sound reducing means uses the operation of an electromagnetic clutch provided in each of the paper feed conveyance paths having a plurality of paper feed stages. It is characterized by comprising a paper feed / transport control means for controlling the electromagnetic clutch to be higher than the paper feed stage.

  The invention according to claim 18 is a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet, and picks up sound at a sound collecting position 1 m away from an end surface of the image forming apparatus to be manufactured. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by the image forming apparatus when image formation is performed on the image forming target sheet, for 1 minute The following formula (a) using the output numerical value (ppm) of the image forming target sheet (A4 size lateral direction)

The probability P calculated by the following condition (b)

A design step of designing each part of the apparatus so as to satisfy the above-mentioned requirements; and a manufacturing step of manufacturing the image forming apparatus according to the design content made by the design step.

  According to a nineteenth aspect of the present invention, there is provided a method of manufacturing an image forming apparatus that forms an image on an image forming target sheet, and picks up sound at a sound collecting position that is 1 m away from an end surface of the image forming apparatus to be manufactured. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by the image forming apparatus when image formation is performed on the image forming target sheet, for 1 minute The following formula (d) using the output numerical value (ppm) of the image forming object sheet (A4 size lateral direction)

The probability P calculated by the following condition (b)

A design step of designing each part of the apparatus so as to satisfy the above-mentioned requirements; and a manufacturing step of manufacturing the image forming apparatus according to the design content made by the design step.

  According to a twentieth aspect of the present invention, there is provided a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet, and the sound is collected at a sound collecting position 1 m away from an end surface of the image forming apparatus to be manufactured. A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from sound generated by the image forming apparatus when image formation is performed on the image forming target sheet; The following formula (a) using the image forming speed (v: mm / s) for the target sheet

The probability P calculated by the following condition (e)

A design step of designing each part of the apparatus so as to satisfy the above-mentioned requirements; and a manufacturing step of manufacturing the image forming apparatus according to the design contents made in the design step.

  According to a twenty-first aspect of the present invention, there is provided a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet, and the sound is picked up at a sound collecting position 1 m away from an end surface of the image forming apparatus to be manufactured. A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from sound generated by the image forming apparatus when image formation is performed on the image forming target sheet; Using the image forming speed (v: mm / s) for the target sheet, the following formula (d)

The probability P calculated by the following condition (e)

And a design step for designing each part of the apparatus so as to satisfy the requirements, and a manufacturing step for manufacturing the image forming apparatus in accordance with the design contents made by the design step.

  According to a twenty-second aspect of the present invention, there is provided a method of remodeling an image forming apparatus for forming an image on an image forming target sheet, wherein the image is picked up at a sound collection position 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collection step for collecting sound generated by the image forming apparatus when image formation is performed on the formation target sheet, and the image formation target sheet (A4) per minute obtained from a sound collection result in the sound collection step The following formula (a) using the output value (ppm) in the horizontal direction)

The probability P calculated by the following condition (b)

And a modification step for modifying the configuration of the apparatus so as to satisfy the above condition.

  According to a twenty-third aspect of the present invention, there is provided a method for remodeling an image forming apparatus for forming an image on an image forming target sheet, wherein the image is picked up at a sound collecting position 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collection step for collecting sound generated by the image forming apparatus when image formation is performed on the formation target sheet, and a sound pressure level value, a loudness value of an acoustic physical quantity obtained from a sound collection result in the sound collection step, The following formula (d) using a sharpness value, a tonality value, an impulsiveness value, and an output numerical value (ppm) of the image forming target sheet (A4 size lateral direction) per minute

The probability P calculated by the equation is the following condition (b)

And a modification step for modifying the configuration of the apparatus so as to satisfy the above condition.

According to a twenty-fourth aspect of the present invention, there is provided a remodeling method of an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming is performed at a sound collecting position 1 m away from an end surface of the image forming apparatus to be remodeled A sound collection step for collecting sound generated by the image forming apparatus when image formation is performed on the target sheet, and a sound pressure level value, a loudness value, and a sharpness of an acoustic physical quantity obtained from a sound collection result in the sound collection step Value, tonality value, impulsiveness value, and the following formula (a) using the image forming speed (v: mm / s) for the image forming target sheet

The probability P calculated by the equation is the following condition (e)

And a modification step for modifying the configuration of the apparatus so as to satisfy the above condition.

  The invention according to claim 25 is a method for remodeling an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming is performed at a sound collecting position 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collection step for collecting sound generated by the image forming apparatus when image formation is performed on the target sheet, and a sound pressure level value, a loudness value, and a sharpness of an acoustic physical quantity obtained from the sound collection result in the sound collection step The following equation (d) using the value, the tonality value, the impulsiveness value, and the image forming speed (v: mm / s) for the image forming target sheet

The probability P calculated by the following condition (e)

And a modification step for modifying the configuration of the apparatus so as to satisfy the above condition.

  According to a twenty-sixth aspect of the present invention, there is provided a method for evaluating a sound generated by an image forming apparatus that forms an image on an image forming target sheet at the time of image formation, and a plurality of types of sounds generated by the image forming apparatus at the time of image formation. The paired comparison method is used for the evaluation, and the logistic regression analysis is performed using the difference in psychoacoustic parameter values as the explanatory variable. Formula (f)

And substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (f), and defining P = 0.5 at that time, the probability of sound discomfort A sound quality evaluation formula for predicting sound quality is derived, and sound quality evaluation is performed using the derived sound quality evaluation formula.

  According to a twenty-seventh aspect of the present invention, there is provided a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming apparatus evaluates a plurality of types of sounds generated during image formation by a paired comparison method. The logistic regression analysis was performed using the difference in psychoacoustic parameter values as an explanatory variable, and the following formula for the probability of discomfort in sound quality from the results.

And substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (f), and defining P = 0.5 at that time, the probability of sound discomfort A sound quality evaluation formula for predicting the sound quality is derived, and using the derived sound quality evaluation formula, each part of the apparatus is designed so that the sound quality evaluation based on the sound quality evaluation formula satisfies a predetermined condition, and an image forming apparatus is manufactured according to the design contents It is characterized by.

  The invention according to claim 28 is a method of remodeling an image forming apparatus for forming an image on an image forming target sheet, and is based on a pair comparison method with respect to a plurality of types of sounds generated by the image forming apparatus during image formation. An evaluation is performed, and a logistic regression analysis is performed using the probability of unpleasantness of two sounds as a target variable and the difference between psychoacoustic parameter values as an explanatory variable.

And substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (f), and defining P = 0.5 at that time, the probability of sound discomfort The sound quality evaluation formula for predicting the sound quality is derived, the sound quality evaluation of the image forming apparatus to be modified is performed using the derived sound quality evaluation formula, and the image forming apparatus to be modified is based on the sound quality evaluation result. It is characterized by modifying the configuration.

  According to the present invention, it is possible to reduce an operation sound from giving an unpleasant feeling to a user even in various types of image forming apparatuses and a plurality of operation modes.

Preferred embodiments of an image forming apparatus, a manufacturing method of the image forming apparatus, a remodeling method of the image forming apparatus, and a sound quality evaluation method according to the present invention will be described in detail below.
The present invention is a remodeling method for evaluating noise generated by a general image forming apparatus as described below and taking measures to reduce discomfort given to humans by the noise based on the evaluation. Prior to the description of the method, the configuration of a general image forming apparatus will be described. Note that the present invention is not limited to this embodiment.

(A) Configuration of Image Forming Apparatus There are various forms of image forming apparatuses with different image forming speeds, structures, and apparatus sizes, and typical ones are shown below.

(A-1) Image Forming Apparatus Having Multiple Modes FIG. 1 is an explanatory diagram showing an example of the overall configuration of an image forming apparatus (apparatus having multiple modes) according to an embodiment of the present invention. In FIG. 1, the image forming apparatus is a digital color printer that employs an electrophotographic system, and includes an optical unit 1, a photoreceptor unit 3, a developing unit 4, a transfer unit 5, a fixing unit 46, and a paper feeding unit. 110.
At the time of image formation, an image formation target sheet (including printing paper, OHP sheet, etc., but hereinafter referred to as paper) accommodated in a paper feeding unit 110 disposed at the bottom of the image forming apparatus is shown from the lower right side of the figure. It is transported along a predetermined transport path that rises diagonally to the left. The sheet thus transported is fed out from the sheet feeding unit 110 and is conveyed along the oblique conveyance path from the lower right side to the upper left side of the drawing to the upper side of the sheet feeding unit 110. During this time, the sheet is similarly passed between the four photosensitive units 3, the developing unit 4 and the transfer unit 5 arranged side by side along the conveyance path, and a predetermined image is transferred. The sheet on which the image has been transferred is conveyed to a fixing unit 46 that is disposed further obliquely to the left of the photosensitive unit 3, the developing unit 4, and the transfer unit 5, and the transferred image is fixed by the fixing unit 46.

  As shown in FIG. 2, the optical unit 1 is a unit that extends along an oblique sheet conveyance path such as the lower right to the upper left direction in FIG. 2, and has a housing 11 arranged along that direction. doing. Laser diodes (LD) 17 (Bk: black), 18 (C: cyan), 19 (M: magenta), and 20 (Y: yellow) for each of four colors are attached to the upper portion of the housing 11.

  The housing 11 includes a polygon mirror motor 2 for main scanning line scanning, two-layer fθ lenses 21 and 22 for dot position correction, and long WTL lenses 23, 24, 25 for correcting surface tilt. 26, a cylinder lens or the like for correcting a laser beam diameter (not shown) is attached.

  The polygon mirror motor 2 is integrally formed with two upper and lower six-sided mirrors 27, and the polygon mirror 27 is irradiated with laser light emitted from the LDs 17, 18, 19, and 20. The LDs 17, 18, 19, and 20 corresponding to the respective colors emit light in accordance with the conveyance timing of the paper, and the light (indicated by bold lines in the figure) is a cylinder lens, a polygon mirror 27, two-layer fθ lenses 21 and 22, a long length The photosensitive drum 28 of each color is irradiated via the WTL lenses 23, 24, 25, and 26.

  As the LD unit 17 corresponding to black, it is preferable to adopt a two-beam type. That is, by adopting a two-beam LD, two beams can be written simultaneously when forming a monochrome image, and rapid writing can be performed while suppressing the number of rotations of the polygon mirror motor 2. By reducing the rotation speed of the polygon mirror motor 2 in this way, it is possible to obtain an effect of suppressing noise and an effect of extending the life of the motor.

  For example, when printing in the color mode, the rotational speed of the polygon mirror 27 is 29528 rpm (revolution sperminute) and the printing speed is 28 ppm (pagesperminute). The printing speed is 38 ppm.

  Returning to FIG. 1, the structure of the photosensitive unit 3, the developing unit 4, and the transfer unit 5 in the image forming apparatus will be described. As shown in the figure, this image forming apparatus employs a four-drum tandem image forming method, and this method improves the printing speed in the full-color printing mode and the monochrome printing mode. . Further, as described above, the photoconductor unit 3, the developing unit 4, and the transfer unit 5 are disposed obliquely, thereby reducing the installation space, thereby reducing the size of the entire apparatus.

  The photosensitive unit 3 and the developing unit 4 are independent units for each color. That is, the photosensitive unit 3 and developing unit 4 for magenta (M), the photosensitive unit 3 and developing unit 4 for cyan (C), the photosensitive unit 3 and developing unit 4 for yellow (Y), and black (Bk). 1) and the developing unit 4 are arranged in the above order from the lower right side to the upper left side in FIG. The M, C, and Y photoconductor units 3 except for Bk have exactly the same structure, so that any new unit (M, C, Y) may be used. Good.

The transfer unit 5 is a unit extending along the oblique direction below the photosensitive unit 3 and the developing unit 4 arranged in the oblique direction in the above-described order, and is disposed along the oblique direction. ing. The transfer unit 5 includes a plurality of rollers and an endless transfer belt 29 wound around the rollers. When the roller is rotated by a motor (not shown), the transfer belt 29 is rotated counterclockwise in the drawing, and the sheet fed from the paper feeding unit 110 is placed on the transfer belt 29 and is moved from the lower right side to the upper left side of the drawing. To the side. Further, a P sensor 6 is disposed on the downstream side in the transport direction of the transfer unit 5 (upper left in the drawing), and the P sensor 6 detects the density of the P sensor pattern formed on the transfer belt 29. The detection result is used for control.

Here, sectional views of the photosensitive unit 3 and the developing unit 4 corresponding to the colors shown in FIG. 3 are shown. As shown in the figure, the photosensitive unit 3 has a photosensitive drum 28 (for example, φ30). The photosensitive drum 28 has a hollow cylindrical shape and can be rotated clockwise in the drawing by a driving mechanism described later.
A charging roller 36 (for example, φ11) is disposed above the photosensitive drum 28. The surface of the charging roller 36 is disposed at a position separated from the surface of the photosensitive drum 28 by about 0.05 mm. The charging roller 36 is rotated in the opposite direction to the photosensitive drum 28, that is, counterclockwise in the drawing, and applies a uniform charge on the surface of the photosensitive drum 28.

A cleaning brush 37 is disposed above the charging roller 36. A cleaning brush 39 and a counter blade 38 are disposed on the upper left side of the photosensitive drum 28, and the photosensitive drum 28 is cleaned by these.
A waste toner collection coil 40 is disposed on the left side of the cleaning brush 39, and the waste toner collected by the waste toner collection coil 40 is conveyed to the waste toner bolt 16 shown in FIG. ing.
Next, the developing unit 4 adopts a dry two-component magnetic brush developing system, and includes a developing roller 30, a developing doctor 31, a conveying screw left 32, a conveying screw right 33, a toner concentration sensor 34, And an agent cartridge 35.

  Next, the drive mechanism of the photoreceptor unit 3 will be described with reference to FIG. The photoconductor unit 3 is provided for each color, and there are four units. Three photoconductor units 3 for M, C, and Y (for color), and a photoconductor unit 3 for Bk Are driven by separate drive mechanisms. That is, the color photoconductor unit 3 is driven by the color drum drive motor 41 as a drive source and the gears 43 and 44 and the joint 45 that transmit this drive force.

  On the other hand, the black photoconductor unit 3 is driven by another gear 44 and a joint 45 which use another black drum drive motor 42 as a drive source and transmit this drive force. Accordingly, during color mode printing, only the color drum drive motor 41 operates and the black drum drive motor 42 stops. On the other hand, during monochrome mode printing, only the black drum drive motor 42 operates and the color drum drive motor 41 stops. The color drum drive motor 41 and the black drum drive motor 42 are stepping motors.

  As shown in FIGS. 5 and 6, the fixing unit 46 employs a belt fixing system, and the belt has a smaller heat capacity than the fixing roller. There are advantages over the method used, such as shortening the warm-up time and lowering the roller set temperature during standby.

  The fixing unit 46 heats and pressurizes the sheet on which the image has been transferred, and fixes the toner image on the sheet. The fixing unit 46 includes a fixing belt 13 and an oil application unit 47. In the oil application unit 47, the gel oozes out from the oil and is supplied from the application felt 48 to the application roller 49. A small amount of silicone oil is applied to the fixing belt 13 while the application roller 49 rotates.

  By thus applying oil to the fixing belt 13, the fixing belt 13 and the paper are easily peeled off. The application operation by the oil application unit 47 is performed every time one sheet is conveyed, and oil application is performed each time one sheet is conveyed by a mechanism having a solenoid and a spring (not shown). The unit 47 is driven and brought into contact with the fixing belt 13. On the other hand, when one sheet of paper passes, the oil application unit 47 is separated from the fixing belt 13 by the above mechanism.

Further, as shown in FIG. 5, a cleaning roller 50 is provided on the upstream side of the fixing belt 13 in the sheet conveyance direction, and the cleaning roller 50 adsorbs dirt on the fixing belt 13, thereby performing belt cleaning. Made.
The above is the configuration of the fixing unit 46, and the sheet that has passed through the fixing unit 46 is conveyed to the main body tray 90 shown in FIG.

  Next, the configuration of the paper feeding unit 110 will be described with reference to FIG. The paper feeding unit 110 has three trays, a first tray 9, a second tray 10, and a manual paper feeding tray 8. Each of these trays employs an FRR paper feeding system as a system for feeding out the paper stored in the tray. The feed mechanism using the FRR paper feed system is reversely rotated with respect to a paper feed roller that is driven to rotate in the paper feed direction in order to separate the paper fed from the paper bundle stacked in the paper feed tray one by one. It has a configuration in which a roller is in contact.

  Under this configuration, the reverse roller is applied with a weak torque in the opposite direction to the paper feed roller via the torque limiter, so that the reverse roller is in contact with the paper feed roller, or one sheet of paper is In the state of entering between the rollers, the sheet rotates with the sheet feeding roller, while in the state of being separated from the sheet feeding roller, or in the state in which two or more sheets enter between the rollers, it rotates in the reverse direction. For this reason, when the multi-feed paper enters, the paper in contact with the reversing roller is returned to the downstream side in the paper feeding direction, and multi-feed is prevented.

The sheets stored in the first tray 9 are separated by the first sheet feeding unit 51 and sent out from the first tray 9. Then, the fed sheet is transported by the relay roller 53 and reaches the transport roller 55. Here, the sheet is conveyed toward the upper left registration roller 7 while being turned by the conveyance roller 55.
The conveyed sheet hits the resist roller 7 that is stopped, and thereby the skew of the sheet is corrected. Then, timing adjustment with the image forming process by the photoconductor unit 3 or the like is performed, a registration clutch (not shown) is connected at a predetermined timing, the registration roller 7 is driven, and the sheet is conveyed toward the transfer unit. Thereafter, the sheet is conveyed by the transfer belt 29 as described above, and is subjected to processing such as predetermined image transfer.

  The paper stored in the second tray 10 is transported toward the transport roller 55 by the second paper feed unit 52 and the relay roller 54, and thereafter the same as the paper stored in the first tray 9. It is. Further, the paper set on the manual feed tray 8 is transported toward the registration roller 7 by the paper feed unit 56, and the subsequent processing is the same as the paper transport from the first tray 9.

Next, a configuration for driving the first paper feed unit 51 and the second paper feed unit 52 that feed paper from the first tray 9 and the second tray 10 as described above will be described.
As shown in FIG. 8, both these units are driven by a single stepping motor 83, and the driving force is transmitted to each unit via a first paper feed clutch 57 and a second paper feed clutch 58. Is called. That is, when the paper is sent out from the first tray 9, only the first paper feed clutch 57 is engaged, and when the paper is sent out from the second tray 10, only the second paper feed clutch 58 is engaged.

  As described above, this image forming apparatus has the color photoconductor unit 3 and the like, and can perform color printing as well as monochrome printing. More specifically, as shown in Table 1, the printer has four printing modes such as “monochrome mode”, “color mode 1”, “color mode 2”, and “OHP / thick paper mode”, which are operated by the user. When a mode is selected by operating a unit or the like, a control unit (operation control unit) of the image forming apparatus (not shown) controls each unit according to the selection and operates each unit in the operation mode.

In this image forming apparatus, the control unit switches the image forming speed to three types (182.5 mm / s = 38 ppm (pagesperminute), 125.0 mm / s = 28 ppm, 62.5 mm / s = 14 ppm) depending on the mode selected by the user. It has become.
That is, control is performed so that the rotational speeds of the motors such as the stepping motor 83, the black drum driving motor 42, and the color drum driving motor 41 are changed according to the selected operation mode. In this specification, “ppm” refers to the number of output sheets per minute of A4 landscape paper.

  Here, in the high-resolution “color mode 2” and “OHP / thick paper mode”, the printing speed (image forming speed) is 14 ppm, whereas in the “monochrome mode”, the printing speed is 38 ppm, which is nearly three times higher. There is a speed difference. In order to realize such a large speed difference with a single motor, this image forming apparatus employs a stepping motor as a drive source for a paper transport mechanism system and the like.

(A-2) Configuration of Desktop (Desktop) Image Forming Apparatus FIG. 9 is an explanatory diagram showing a configuration example of the image forming apparatus (desktop) according to the embodiment of the present invention. The image forming apparatus is a digital monochrome printer that employs an electrophotographic system, and operates in a single mode (monochrome print only).
In FIG. 9, a photosensitive drum 301 on which an electrostatic latent image and a toner image are formed, a transfer roller 302 for transferring a toner image formed on the photosensitive drum 301 to a recording sheet, and a toner on the photosensitive drum 301 Process cartridge 303 for forming an image, main body paper feed tray 304 for feeding out recording paper one by one, bank paper feed tray 305 for feeding out recording paper one by one in the same manner as the main body paper feed tray 304, and one sheet of recording paper are inserted A manual feed tray 306 for feeding paper, a fixing unit 307 for fixing the toner image transferred to the recording paper by the action of heat and pressure, a writing unit 308 for writing an image on the photosensitive drum 301, and after fixing A paper discharge tray 309 for discharging the recording paper, a paper feed roller 310 for feeding out the recording paper, and alignment with the toner image on the photosensitive drum 301 Registration rollers 311 to start / stop to perform, and a discharge roller 312 for conveying the recording paper to the discharge tray 309.

  In FIG. 9, the image forming apparatus is provided with a paper feed conveyance system such as a main body paper feed tray 304, a bank paper feed tray 305, a manual feed tray 306, a paper feed roller 310, and a registration roller 311. After the image is transferred from the paper feed conveyance system through the image forming side of the process cartridge 303, the image is discharged to the paper discharge tray 309 through the fixing unit 307 and the paper discharge roller 312. This image forming speed is 90 mm / s.

  A writing unit 308 including an LD unit, a polygon mirror, an fθ lens (all not shown) and the like are disposed above the process cartridge 303. In addition, although not shown, a drive transmission system including a drive motor, a solenoid, and a clutch (mechanical clutch, electromagnetic clutch) for rotationally driving the photosensitive drum 301 and each roller is provided. In the image forming apparatus configured as described above, driving sound of the drive motor and the drive transmission system, operation sound of the solenoid clutch, feeding sound of the recording paper, charging sound, and the like are emitted during image formation.

  FIG. 10 is an explanatory diagram showing a configuration example of the process cartridge 303 in FIG. The process cartridge 303 includes a charging roller 321 as a charging unit, a developing roller 322 as a developing unit, a cleaning blade 323 as a cleaning unit, an agitator 325 that stirs toner 324 and sends it to the developing roller 322, and a stirring shaft 326. And a developing blade 327. The charging roller 321 includes a cored bar 321a and a charging unit 321b.

  Around the photosensitive drum 301 as an image carrier, a charging roller 321, a developing roller 322, and a cleaning blade 323 are arranged under predetermined conditions. The toner 324 in the process cartridge 303 is stirred by the agitator 325 and the stirring shaft 326 and is conveyed to the developing roller 322. The toner 324 attached to the roller surface by the magnetic force in the developing roller 322 is negatively charged by frictional charging when passing through the developing blade 327. The negatively charged toner moves to the photosensitive drum 301 by the bias voltage and adheres to the electrostatic latent image.

  When the recording paper sent by the registration roller 311 passes between the photosensitive drum 301 and the transfer roller 302, the toner on the photosensitive drum 301 is transferred to the recording paper by the positive charge from the transfer roller 302. The toner remaining on the photosensitive drum 301 is scraped off by the cleaning blade 323 and is collected as waste toner in a tank above the cleaning blade 323. The parts other than the transfer roller 302 are integrated as a process cartridge 303 so that the user can replace it.

  FIG. 11 is an explanatory diagram showing the configuration of the charging roller 321 in FIG. As shown in FIGS. 10 and 11, the charging roller 321 is charged so that the surface of the photosensitive drum 301 is uniformly primary charged by being driven by frictional force while always contacting the photosensitive drum 301 at a predetermined pressure. It is a member. As shown in FIG. 10, the charging roller 321 includes a cored bar 321a serving as a rotating shaft and a charging unit 321b formed concentrically around the cored bar 321a.

  When the charging roller 321 is charged, an AC voltage is superimposed on the DC voltage on the cored bar portion 321a via the electrode terminal 331, the charging roller pressure spring 332, and the conductive bearing 333 from a high voltage power source. The applied bias voltage is applied, and the charging roller 321 uniformly charges the photosensitive drum 301 to the same voltage as the DC component of the bias voltage. The AC component of the bias voltage functions to uniformly charge the photosensitive drum 301 by the charging roller 321 uniformly.

  By the way, when the photosensitive drum 301 is contact-charged by the charging roller 321, an attractive force and a repulsive force act alternately between the surfaces of the charging roller 321 and the photosensitive drum 301 due to the AC component of the bias voltage, and the charging roller 321. Causes vibration. This vibration of the charging roller 321 causes an irritating vibration sound (charging sound) having a high frequency in the charging roller 321 itself, and is also transmitted to the photosensitive drum 301 side to vibrate the photosensitive drum 301 and generate noise. Let

(A-3) Configuration of Medium-Speed Image Forming Apparatus FIG. 12 is a front view showing a schematic configuration of an image forming apparatus (medium-speed digital copying machine) according to the embodiment of the present invention. In FIG. 12, the image forming apparatus mainly includes a main body 401 and a paper feed bank unit 402 capable of two-stage paper feed. Since the main body 401 is provided with a two-stage paper feed tray, the function of the image forming apparatus can be exhibited only by the main body 401 without the paper feed bank unit 402. Further, instead of the paper supply bank unit 402, an inexpensive supply storage table (not shown) having the same outer shape can be attached. A route indicated by a solid arrow in the drawing is a paper conveyance route at the time of image formation when paper is fed from the first tray 410 of the main body 401. When paper is fed from the second tray 411 of the main body 401 and the first tray 412 and the second tray 413 of the paper feed bank unit 402, the paper transport route is indicated by a broken line. Specifically, it joins the same route as the first tray 410 of the main body 401.

  Inside the main body 401, a charging roller 407, a writing system optical unit 404, a developing roller 408, a transfer roller 409, and the like arranged around a drum-shaped photoconductor 406 are arranged. A unit 403, a registration roller pair 416, a toner bottle 421, a fixing device 417, a paper discharge roller pair 419, and the like are arranged.

  Next, the operation of the image forming apparatus will be described. First, document data is read by the reading system optical unit 403 and converted into a digital electric signal. This digital electrical signal is subjected to image processing and sent to the writing optical unit 404. A light beam 405 based on the digital signal is emitted from the writing system optical unit 404 and irradiated onto the photoconductor 406. The photosensitive member 406 is driven to rotate counterclockwise in FIG. 12, and the surface is uniformly charged by the charging roller 407, and the original image is written on the charged surface by the writing system optical unit 404 as described above. As a result, an electrostatic latent image is formed on the photosensitive member 406, and this latent image is visualized as a toner image by the developing roller 408. Toner is supplied from a toner bottle 421 to a developing unit including the developing roller 408.

  On the other hand, a paper supply operation will be described using an example in which paper is fed from the first tray 410 of the main body 401. Only one sheet is separated from the first-stage tray 410 in which the sheets are stacked and stacked by the sheet feeding roller 414. The separated sheet is turned upward while being assisted by the conveyance auxiliary roller 415, and is directed upward, is abutted against the registration roller pair 416, is subjected to registration adjustment and timing adjustment, and then proceeds to the image forming unit. .

  An image formed of toner on the photoconductor 406 is transferred to the paper when the paper passes between the photoconductor 406 and the transfer roller 409. Thereafter, the toner is conveyed to the fixing device 417, and the toner is fixed on the paper by the fixing roller pair 418 of the fixing device 417, and is discharged to the paper discharge tray 420 by the paper discharge roller pair 419. The image forming speed of the image forming apparatus according to the above embodiment is, for example, about 122 mm / s, and 27 images can be formed per minute.

(A-3) Configuration of Large (Console Type) Image Forming Apparatus FIG. 13 is an explanatory diagram showing a configuration example of an image forming apparatus (console type) according to an embodiment of the present invention. That is, the overall height is designed to be used by installing on the floor surface, and the whole is the upper part (ADF (automatic document feeder) 510, scanner 520, writing unit 530, image forming engine 540) 500, lower part (bank). A console type digital MFP (multi-function printer) composed of a paper feed unit 570) is shown. In other words, there may be provided a normal copy function, a printer function according to an instruction from a personal computer, and a facsimile function. This type of image forming apparatus is generally a high speed machine.

  The upper part 500 includes an optical unit in which optical elements (scanner 520 and writing unit 530) are housed in a casing, an image forming engine 540 positioned below the optical unit, and an ADF 510 disposed on the upper part of the casing.

  In FIG. 13, a photosensitive drum 501 as an image carrier on which an electrostatic latent image is formed, a charging charger 502, a developing unit 503, a transfer / separation charger 504, a cleaning unit 505, a fixing unit 506, a registration roller 507, a document table. 511, contact glass 512, exposure lamp 513, first mirror 514, second mirror 515, third mirror 516, imaging lens 517, CCD 518, mirror 519, and caster 590 with a lock function.

  That is, the scanner 520 includes a contact glass 512 on which a document is placed and a scanning optical system. The scanning optical system includes a first carriage on which an exposure lamp 513 and a first mirror 514 are mounted, a second carriage that holds the second mirror 515 and the third mirror 516, an imaging lens 517, and a CCD 518. . A first carriage that is driven by a stepping motor and moves at a constant speed when reading an original is provided, and a second carriage that is driven at a speed half that of the first carriage.

  A document (not shown) on the contact glass 512 is optically scanned by the first carriage and the second carriage, and the reflected light obtained there is an exposure lamp 513, a first mirror 514, a second mirror 515, a third mirror. An image is formed on the CCD 518 via the mirror 516 and the imaging lens 517, and photoelectrically converted.

The writing unit 530 includes a laser output unit, an fθ lens, a mirror (all not shown), and the like. The laser output unit is provided with a laser diode and a polygon mirror which are laser light sources.
The image signal output from the image processing unit is converted into laser light having an intensity corresponding to the image signal by the writing unit 530, and is shaped into a light beam having a fixed shape by a collimating lens, an aperture, and a cylinder lens, and then converted into a polygon mirror. Irradiated and output. The laser beam output from the writing unit 530 is applied to the photosensitive drum 501 through the mirror 519. The laser beam that has passed through the fθ lens is applied to a beam sensor (not shown) that generates a main scanning synchronization detection signal arranged outside the image area.

  The ADF 510 conveys originals set on the original table 511 one by one to the contact glass 512, and discharges them after reading. That is, the document is set on the document table 511 and the width direction is aligned by the side guide. The documents on the document table 511 are fed one by one from the bottom document by a feed roller, and are sent onto the contact glass 512 by the transport belt. After the document on the contact glass 512 is read, the document is discharged onto the discharge tray by the transport belt and the discharge roller.

  The recording sheets stacked on the first tray 571, the second tray 572, the third tray 573, and the fourth tray 574 of the bank sheet feeding unit 570 are the first sheet feeder 575, the second sheet feeder 576, and the second sheet feeder 576, respectively. The paper is fed by a third paper feeding device 577 and a fourth paper feeding device 578 and further conveyed by a bank vertical conveyance unit 579 and a main body vertical conveyance unit 580. When the leading edge of the recording paper is detected by a registration sensor (not shown), the recording paper is conveyed for a predetermined time, and then temporarily stops at the nip portion of the registration roller 507 and enters a standby state.

  The waiting recording paper is sent to the photosensitive drum 501 side in accordance with the timing of the image valid signal, and is brought into close contact with the photosensitive drum 501 by the transfer on of the transfer / separation charger 504, and the image is transferred. Further, the recording paper is separated from the photosensitive drum 501 by separation on from the photosensitive drum 501. The recording paper onto which the toner image has been transferred is conveyed by a conveying device, fixed by the heat and pressure action of the fixing unit 506 including a fixing roller and a pressure roller, and discharged to the outside by a paper discharge roller 581. . The image forming speed of the image forming apparatus according to the embodiment is, for example, about 362 mm / s.

As described above, the image formation on the photosensitive drum 501 is performed by irradiating the charge charged on the photosensitive drum 501 by the charger 502 with the laser beam to form an electrostatic latent image, and the developing unit 503 performs the photosensitive operation. An image is formed on the body drum 501.
When double-sided printing is performed using the double-sided unit 585, the recording sheet after fixing is guided to the double-sided conveyance path 586 by the switching claw 582, and is accumulated on the double-sided tray through the feed roller and the separation roller. The recording paper accumulated in the tray is brought into contact with the feed roller when the tray is raised, and is fed to the main body vertical conveyance unit 580 when the feed roller rotates, and is re-fed to the registration roller 507 and then back to the back surface. Is printed.

  When performing reverse paper discharge, the recording paper is guided to the reverse tray by the switching claw, and when the trailing edge of the recording paper passes the reverse detection sensor, the transport roller is reversed and guided to the paper discharge tray. Paper is ejected to the set tray.

(B) Sound quality evaluation method The present invention is a remodeling method for evaluating noise generated by the image forming apparatus as described above, and taking measures to reduce discomfort caused to the person by the noise based on the evaluation. A method for evaluating noise generated during image formation by the image forming apparatus having the above configuration will be described.

  As a method for evaluating the sound quality, it is conceivable to derive a sound quality evaluation formula that can predict the sound quality from the experimental results obtained by the Scheffe paired comparison method. In the paired comparison method, two stimuli pairs are created for a stimulus that is difficult to be absolutely evaluated, such as a sound generated by an image forming apparatus, and a pair is formed by all combinations of stimuli to be evaluated. The difference is obtained, and a relative average score is given for each stimulus. This method focuses on the fact that it is difficult for humans to evaluate one stimulus, but it is relatively easy to compare two stimuli to determine which is better or worse. It is.

For example, if there are three stimuli A1, A2, A3,
y1 = μ + α1, y2 = μ + α2, y3 = μ + α3
And For simplicity, it is assumed that this model is composed only of the total average μ and the main effect αi (i = 1, 2, 3). In addition, the sum of the main effects is set to 0, as in the general constraint necessary for parameter estimation in the design of experiments.
α1 + α2 + α3 = 0 (1)

  The fact that absolute evaluation is impossible means that there is no idea about the value of μ, so that y1, y2, and y3 cannot be measured directly. As described above, the difference between the two stimuli By removing, μ disappears and can be expressed by the difference of the main effect only.

y1-y2 = (μ + α1) − (μ + α2) = α1-α2 (2)
y1−y3 = (μ + α1) − (μ + α3) = α1−α3 (3)
y2-y3 = (μ + α2) − (μ + α3) = α2-α3 (4)
Where (2) + (3) is
2y1- (y2 + y3) = 2α1- (α2 + α3)
However, according to the constraint equation (1), 2y1- (y2 + y3) = 3α1
It becomes. That is, the effect of each stimulus can be extracted. Then, if the effect of each stimulus at this time is expressed by a linear function by the difference in physical characteristics of the image forming apparatus,
α1-α2 = b (x1-x2) (5)
The relationship is obtained. Here, b is a constant. Similar relationships can be obtained for other combinations of xi (i = 1, 2, 3... N).

  The intercept cancels because it models the difference between the two stimuli. Therefore, multiple regression analysis using the difference in scores (difference between the scores of a pair of sounds obtained from a paired comparison experiment) as the objective variable and the difference between multiple physical characteristics (such as psychoacoustic parameters) as explanatory variables. As a result, a model for predicting the difference in evaluation is obtained. That is, when a physical characteristic value of two sounds to be compared is input, a model that can output a prediction of an evaluation difference such as how discomfort is different between the two sounds can be obtained.

  The present inventor applies a neural network model of a standard type (only one hidden layer) as shown in FIG. 14 as a sound quality evaluation prediction model separately from the evaluation difference prediction model as described above. did. For the analysis, statistical analysis software “JMP (registered trademark of SAS Institute)” was used.

Neural network analysis is a technique for building a flexible function network from input signals and predicting the output response from it. The model can be expressed only with the main effect, and there is no need to consider the interaction. It is effective for prediction when the output function is nonlinear and unknown.
There may be a plurality of hidden layers. In other words, as long as the number of hidden layers is sufficient, any aspect can be approximated with arbitrary accuracy.

In addition, the following items are raised as disadvantages.
・ Because there is a hidden layer between input and output and complicated processing is performed, physical interpretation of the neural network model is difficult.
・ It tends to be overfit for specific data, and there is a tendency that future data prediction cannot be performed well.
-Since it is not a fixed fitting method for unknowns, the objective function often converges before the unknowns stabilize.
・ Because there is a local optimal solution, a different result may be obtained each time the analysis is performed, or many of the converged estimated values may not be optimal.

  Since there is a local optimal solution, the model estimation is repeated many times using a random starting estimate. Since processing is performed using a random starting estimation value, the parameter estimation value changes each time an analysis (trial) is performed. Therefore, it is necessary to repeat the trial and examine the stability of the model. One start estimate and one iteration using it are called a tour. In the statistical analysis software “JMP”, the default number of tours is set to 20, and a simple model can be applied to 20 tours well.

The actual calculation was performed as follows.
First, the input variable xi is scaled to a range of 0-1. The hidden layer Hj is obtained by converting and adding input variables scaled in the range of 0 to 1 with an S-shaped function (normal logistic (sigmoid)) function.
The output variable y is scaled to a range of 0 to 1 by adding the hidden layer Hj, and further linearly transformed.

  The above is the explanation of the neural network analysis, and the present inventor has derived the sound quality evaluation formula using the neural network analysis and performed the sound quality evaluation using the evaluation formula. Hereinafter, the process will be described in detail based on actual experiments and the like.

The flow of the sound quality evaluation experiment of the image forming apparatus, the identification of the unpleasant sound source, and the derivation of the sound quality evaluation formula are as follows.
(1) Collection of operation sound of image forming apparatus (2) Analysis of operation sound (3) Creation of test sound from collected operation sound (4) Measurement of psychoacoustic parameters of test sound (5) For each model or mode Of the paired comparison method using the test sound of the test piece (Modification of Scheffe's paired comparison method Ura)
(6) Identification of unpleasant sound source (7) Creation of difference model analysis data (8) Derivation of formula for predicting uncomfortable probability between two sounds (9) Model formula (sound quality evaluation formula) for predicting unpleasant probability of sound Derivation (10) Verification of derived sound quality evaluation formula

Details of the above process will be described below.
(1) Collection of operation sound of image forming apparatus The operation sound of the image forming apparatus was recorded by binaural (binaural) recording using a dummy head HMS (Head Measurement System) III manufactured by Head Acoustics. This is because by performing binaural recording and reproducing with dedicated headphones in this way, it can be reproduced as if a human actually heard the sound generated by the machine.
In addition, as described above, the image forming apparatus that is a device under test executes image forming operations at three types of image forming speeds according to the operation mode for an image forming apparatus having a plurality of modes. Measurement was performed for each of the three operation modes.
Further, since the desktop type (desktop) image forming apparatus, the medium-speed image forming apparatus, and the large-sized (console type) image forming apparatus have only a monochrome single mode, their operations were measured.

The measurement conditions are as follows (see FIG. 15).
・ Sound recording environment ・ ・ ・ Semi-anechoic room ・ Dummy head 203 ear position (sound collecting position) 204 ・ ・ ・ Height 1.2m
Horizontal distance of 1 m (1 ± 0.03) from the end surface of the device 201 to be measured, the width direction is the center position of the device. • Recording direction: Four directions: front (surface with the operation unit 202 of the image forming apparatus), rear surface, and left and right surfaces.・ Recording mode ... FF (Free field: for anechoic room)
・ HP filter 22Hz

  The height of the dummy head is set to 1.2 m in consideration of the fact that there are many cases where an instruction is issued from a personal computer or the like while the user is seated as a recent method of using the image forming apparatus. . Of course, the dummy head may be installed at a height of 1.5 m in consideration of a state where a human is standing.

  By the way, the sound generated by the image forming apparatus is usually different for each direction. This is because the positions of various motors, the sheet conveyance path, and the position of the paper discharge port are not located at the center of the apparatus but are distributed. Therefore, the sound produced by a certain sound source (such as a motor) can be heard well on the right side, but the sound collected for each direction is different, such as not being heard well on the left side. The sample sound used for the experiment described below may be collected in any direction, but when performing a paired comparison experiment, it is necessary to unify the sample sound in any one direction. Therefore, in this experiment, it is considered that the user has the most chances of listening on the front side, while the rear side of the normal image forming apparatus has little opportunity to hear the sound on the rear side that is installed along the wall. Therefore, we decided to use the sampled sound from the front side as the test sound.

(2) Analysis of operation sound Next, the operation sound of the image forming apparatus collected as described above was analyzed.
First, when an image forming apparatus having a plurality of modes was analyzed for noise when operating at a color printing speed of 28 ppm, an analysis result as shown in FIG. 16 was obtained. FIG. 16A represents a sound collected on the time axis, and FIG. 16B represents a sound collected on the frequency axis. From this result, seven main sound sources were extracted.
First, the fixing oil application impact sound of the fixing unit 46 was extracted on the time axis. On the frequency axis, color development drive system sound, paper feed stepping motor sound, charging sound, drum drive stepping motor sound, polygon mirror motor sound, and paper sliding sound were extracted.

  Next, when the noise when the color printing speed was operated at 14 ppm was analyzed, an analysis result as shown in FIG. 17 was obtained. FIG. 17A represents a sound collected on the time axis, and FIG. 17B represents a sound collected on the frequency axis. From this result, as the main sound source, the fixing oil application impact sound is extracted on the time axis, and the feeding stepping motor sound, charging sound, drum drive motor sound, polygon mirror motor sound, paper sliding sound are extracted on the frequency axis. Extracted.

  Next, when the noise when operating at a monochrome printing speed of 38 ppm was analyzed, an analysis result as shown in FIG. 18 was obtained. FIG. 18A shows a sound collected on the time axis, and FIG. 18B shows a sound collected on the frequency axis. From this result, as a main sound source, fixing oil application impact sound was extracted on the time axis, and development drive system sound, charging sound, drum driving stepping motor sound, and paper sliding sound were extracted on the frequency axis.

  Next, when the noise when the desktop (desktop) image forming apparatus (20 ppm) was operated was analyzed, an analysis result as shown in FIG. 19 was obtained. FIG. 19A represents a sound collected on the time axis, and FIG. 19B represents a sound collected on the frequency axis. From these results, metal (clutch / solenoid) impact sound and paper impact sound were extracted on the time axis as main sound sources, and main motor sound and AC charging sound were extracted on the frequency axis.

  Next, when the noise when the medium-speed image forming apparatus (27 ppm) was operated was analyzed, an analysis result as shown in FIG. 20 was obtained. FIG. 20A represents a sound collected on the time axis, and FIG. 20B represents a sound collected on the frequency axis. From these results, as the main sound source, paper feed sound and metal (clutch / solenoid) impact sound were extracted on the time axis, and main motor sound, paper feed sound, and paper sliding sound were extracted on the frequency axis.

  Next, when the noise when the large (console type) image forming apparatus (65 ppm) was operated was analyzed, an analysis result as shown in FIG. 21 was obtained. FIG. 21A represents a sound collected on the time axis, and FIG. 221B represents a sound collected on the frequency axis. From these results, paper impact sounds and metal (clutch / solenoid) impact sounds are extracted on the time axis as main sound sources, and paper impact sounds, bank motor sounds, development motor sounds, main motor sounds, paper on the frequency axis. The sliding sound was extracted.

(3) Creation of test sound from the collected operation sound Next, as described above, the sound collected at the position on the front side of the device was collected using “ArtemiS”, a sound quality analysis software manufactured by Head Acoustics. The sound was processed.

  As a sound processing method performed in this experiment, a sound during one cycle period of the printing operation is cut out from the collected original sound, and a part related to the main sound source extracted as described above among the sounds during the one cycle period. Filter processing was performed on the frequency axis or time axis, and processing for attenuating or enhancing these portions was performed. That is, three levels of sound (emphasis / original sound / attenuation) were created for each sound source extracted in one mode.

  As described above, the sounds collected on the front, rear, left and right sides of the image forming apparatus are different from each other, but on the front side created in this experiment rather than the range of psychoacoustic parameter values obtained from such four-direction sounds. It has been confirmed that the range of psychoacoustic parameter values obtained from three test sounds obtained by emphasizing and attenuating the collected sounds is wider. In other words, a subjective evaluation experiment using three sounds obtained by emphasizing and attenuating the sound collected on the front side as in this experiment covers the characteristics of the sound obtained from the sound collected in four directions. Therefore, the discomfort in the four directions can be calculated from the sound quality evaluation formula.

Based on the sound collected on the front side as described above, if three levels of sound (emphasis, original sound, attenuation) are created from the sound emitted by the main sound source extracted for each image forming apparatus, the sound generated at the time of each image formation Nine sounds were created based on the L9 orthogonal table with different levels of sound sources extracted for.
In Scheffe's paired comparison method (Ura's modified method), it is necessary to perform a comparison experiment with brute force combinations of the test sounds. 72 comparisons were made.

First, an image forming apparatus having a plurality of modes will be described. Tables 2 to 5 are descriptions relating to respective modes of the image forming apparatus having a plurality of modes.
Here, Table 2 shows three-level sounds created for the main sound sources (seven) extracted from the sounds collected when the image forming apparatus having a plurality of modes is operated at a color printing speed of 28 ppm. 9 shows the result of creating nine test sounds assigned based on the above. By assigning to the orthogonal table in this way, there is no correlation between each factor (change in the level of the sound source), so analysis can be performed ignoring changes in other factors.

  In Table 2 above (the same applies to the following tables), “−1” is a sound that is attenuated until the sound is almost inaudible, “0” is a sound at the level of the original sound, and “1” is the original sound. The sound is emphasized until the difference in level is clearly understood. For example, the test sound “color 28 ppm 9” in Table 2 has “0” attached to all sound sources, and thus indicates that all remain as original sounds.

  In Tables 2 to 9, the subjective evaluation values (scores) of the test sounds obtained by the Scheffe paired comparison method (Ura's modified method) are also shown. It should be noted that the total of subjective evaluation values (total of nine sounds) in Tables 2 to 9 is set to 0 in each table.

  Next, Table 3 shows the result of allocating the three levels of sounds created for the main sound sources (six) extracted from the sound collected when operating at a color printing speed of 14 ppm based on the L9 orthogonal table. . However, since the charging sound, the drum driving stepping motor sound, and the polygon mirror motor sound are sounds of the same tonality component, each test sound was set to the same level. The paper feed stepping motor sound is also a tonality component, but since this is an intermittently generated sound, it was decided to swing the level separately from the motor sound.

  In this experiment, three levels of sound are obtained from the psychoacoustic parameters loudness value, sharpness value, tonality value and impulsiveness value obtained from the sound collected in the front when the above three modes are mixed. (Emphasis, original sound, attenuation) were created, and these sounds were assigned based on the L9 orthogonal table to create test sounds. The results are shown in Table 5.

  As for the assignment of the loudness value, the emphasis was given to 38 ppm for monochrome, the intermediate one for 28 ppm, and the attenuated one for 14 ppm. That is, each level value of loudness was assigned according to the printing speed. The numerical values in parentheses in the table indicate each parameter value. In this experiment, since the effect of the printing speed (ppm), that is, the effect of the printing speed is also checked, the effect cannot be analyzed if the printing speed and the loudness value change in a completely proportional manner. Therefore, as shown in Table 5, even if the loudness values are the same level, a difference of about 1 (sone) is given to make a difference in the level of hearing.

Similarly, similar operations were performed on image forming apparatuses at other speeds.
Table 6 shows the result of allocating the three levels of sounds created for the main sound sources (three) extracted from the sound collected when operating at monochrome 20 ppm based on the L9 orthogonal table.

  Table 7 shows the result of allocating three levels of sound created for the main sound sources (four) extracted from the sound collected when operating at monochrome 27 ppm based on the L9 orthogonal table.

  Table 8 shows the results of allocating the three levels of sounds created for the main sound sources (six) extracted from the sound collected when operating at 65 ppm monochrome based on the L9 orthogonal table.

  Also, in this experiment, three values were obtained from the loudness value, sharpness value, tonality value, and impulsiveness value, which are psychoacoustic parameters obtained from the sound collected at the front when the three speeds of the monochrome machine were mixed. Level sounds (emphasis, original sound, attenuation) were created, and these sounds were assigned based on the L9 orthogonal table to create test sounds. The results are shown in Table 9.

Furthermore, the six sounds related to the image forming apparatus having a plurality of modes (14 ppm for color, 28 ppm for color, and 38 ppm for monochrome) and the six sounds of the image forming apparatus having a monochrome single mode were compared. Table 12 shows the 12 sounds.
The above is the details of the process of creating a test sound from the collected operating sound and creating an experiment.

(4) Measurement of psychoacoustic parameters of test sound Next, the psychoacoustic parameters of the test sound created as described above were obtained using the sound quality analysis software “ArtemiS” manufactured by Head Acoustics. In this sound quality analysis software, various settings can be selected when obtaining psychoacoustic parameters. In this experiment, default settings were adopted.

For example, for loudness, "FFT / ISO0532", "Filter / ISO0532" and "FFT / HEAD" can be selected as "Caluculationmethod", but the default "FFT / ISO0532" is adopted, and "SpectrumSize" is the default "SpectrumSize" 4096 ".
As for sharpness, the default “Fluctuation method” adopts “FFT / ISO532”, and the “Sharpnessmethod” adopts the default “Aures” among “Aures” and “vonBismarck”. “SpectrumSize” was set to the default “4096”. Other psychoacoustic parameters correlate with loudness and automatically change depending on the loudness setting.

  Using the sound quality analysis software set as described above, the psychoacoustic parameter values of the test sound created in the process of (3) “Creating a test sound from the collected operation sound” were obtained. The results are shown in Table 11.

(5) Paired comparison method experiment using test sound for each model or mode (Modification of Scheffe's paired comparison method Ura)
Next, the subjects who have the test sounds created as described above are evaluated, and the test sounds 1 to 9 created for each model or mode (Tables 2 to 10) are collected by the subjects (Table 10 only) 1 to 12) were compared to determine which is uncomfortable.

  In the comparison experiment, all combinations of two test sounds are extracted from nine test sounds, and N subjects compare all of the combinations. That is, since there are nine test sounds in one mode, there are 72 combinations, and the subject is made to compare them. Therefore, the evaluation of the combination of the sample sound 1 and the sample sound 2 is different from the evaluation of the combination of the sample sound 2 and the sample sound 1, and the combinations with different order of listening are also subject to the experiment. Become.

  In this comparison, for example, the test sound 1 is compared with the test sound 2, and when the subject evaluates the test sound 1 as unpleasant, the test sound 2 is uncomfortable. In this case, “−1 point” was set, and the results were collected and subjected to statistical processing. As a result, relative subjective evaluation values were obtained in the range of −1 to 1 with respect to nine test sounds. Such subjective evaluation values are also shown in Tables 2 to 5. Since the evaluation as described above is performed, it means that the larger the subjective evaluation value, the more unpleasant.

  For the combinations shown in Table 10, the scale of the experiment increases when a 12-round brute force comparison is performed. Therefore, in this experiment, the sounds of the image forming apparatuses having a plurality of modes and the sounds of the image forming apparatus of the monochrome single mode are compared. Was not performed because it was performed in another experiment (Comparison between Group I and Group III, and Group II and Group IV in the table below was not performed). That is, only four comparisons were performed: Group I and Group II, Group I and Group IV, Group II and Group III, and Group III and Group IV. Considering the order of comparison, one subject made 72 comparisons at a time. Since it is not a brute force pair comparison, a relative score of 12 sounds cannot be calculated, but difference data of discomfort of 2 sounds can be obtained.

(6) Identification of unpleasant sound source Next, unpleasant sound source is identified by six operating sounds of “color 28 ppm”, “color 14 ppm”, “monochrome 38 ppm”, “monochrome 20 ppm”, “monochrome 27 ppm”, and “monochrome 65 ppm”. It carried out for every experimental result implemented. Here, FIG. 22 to FIG. 36 are graphs showing the relationship between the level (emphasis, original sound, attenuation) of each sound source shown in Tables 2 to 4 and the subjective evaluation value. 37 to 40 are for Table 6, FIGS. 41 to 44 are for Table 7, and FIGS. 45 to 50 are for each sound source level (emphasis, original sound, attenuation) and subjective evaluation values. The relationship is shown in a graph.

  In this graph, the vertical axis represents the subjective evaluation value α, which means that the higher the value is, the more uncomfortable it is. The horizontal axis of the graph is the level of the sound source, that is, the sound pressure level level, “−1” attenuates the sound source, “0” remains the original sound, and “+1” emphasizes the sound source.

Further, “R ² ” in each figure is a contribution rate, and “R” is a correlation function. Here, the contribution rate indicates what percentage the sound source contributes to discomfort. The results shown in FIG. 22 indicate that the fixing oil application impact sound contributes 51% to discomfort. That is, if the correlation between the sound source level change and the subjective evaluation value (discomfort) change is high, the contribution rate increases. Note that the total contribution rate of each sound source in one mode is 100%, but there are some that are not exactly 100% due to rounding.

First, an unpleasant sound source of an image forming apparatus having a plurality of modes is examined.
Referring to the contribution ratios of the sound sources of “color 28 ppm” shown in FIGS. 22 to 28, the color development driving sound system, the paper feeding stepping motor sound, the AC charging sound, and the polygon mirror motor sound almost contribute to unpleasantness. I understand that there is no. However, according to later analysis, the three sound sources of the feeding stepping motor sound, charging sound, and polygon mirror motor sound are strongly related to the tonality (pure tone) component, which is actually unpleasant, but if the frequency of the pure tone is close, no measures are taken at the same time And found that discomfort is not improved.

Therefore, in other modes, these sound sources are set to the same level for each sample sound (see the process (3) and Tables 3 and 4). For this reason, only the color development driving sound among the sound sources hardly contributes to discomfort, so it is considered that there is no need for noise countermeasures. However, there are cases where improvement is necessary in the evaluation based on the sound power level.
On the other hand, in “Color 28 ppm”, the fixing oil application impact sound contributes most to discomfort, and the second contribution is paper sliding noise.

  According to the unpleasant sound source analysis results of “color 14 ppm” shown in FIGS. 29 to 32, the fixing oil application impact sound 43%, paper sliding sound 35%, paper feeding stepping motor sound 17%, charging sound, polygon mirror motor sound The total of the three sound sources of the drum drive motor sound was 3%.

  According to the unpleasant sound source analysis result of “monochrome 38 ppm” shown in FIGS. 33 to 36, the fixing oil application impact sound is 49%, the paper sliding sound is 38%, the sum of the charging sound and the drum drive motor sound is 10%, and the development drive The sound system was 3%.

  From the above analysis results, in the image forming apparatus having a plurality of modes, sound sources other than the sound of the development drive system contribute to unpleasantness, and if these sound sources are subjected to noise countermeasures, the uncomfortableness is reduced. You can see that

Next, an unpleasant sound source of the desktop (desktop) image forming apparatus is examined.
Since there are few conspicuous sound sources for this device, one of the factors that change the level was substituted with loudness.
Referring to the contribution ratio of each sound source of “monochrome 20 ppm” shown in FIGS. 37 to 40, the influence of loudness was great, and the discomfort of each sound source was not accurately known. It has been found that reducing the overall volume of hearing leads to a reduction in discomfort.

Next, the unpleasant sound source of the medium-speed image forming apparatus is examined.
Referring to the contribution ratio of each sound source of “monochrome 27 ppm” shown in FIG. 41 to FIG. 44, the paper feed sound was 9%, the paper sliding sound was 61%, the metal impact sound was 13%, and the motor drive system sound was 1%. .
In the medium-speed image forming apparatus, the paper sliding sound and the metal impact sound contribute to the uncomfortableness, and it can be understood that the discomfort can be reduced by taking noise countermeasures for these sound sources.

Next, the unpleasant sound source of the large (console type) image forming apparatus is examined.
Referring to the contribution ratio of each sound source of “monochrome 65 ppm” shown in FIGS. 45 to 50, metal impact sound 29%, paper sliding sound 42%, paper impact sound 0%, bank motor sound 3%, development motor sound 10%, main motor sound 1%.
In a large-sized (console type) image forming apparatus, metal impact sound and paper sliding sound contribute to discomfort, and it can be seen that discomfort can be reduced by taking noise countermeasures for these sound sources.

(7) Creation of analysis data of difference model Next, using the experimental results obtained by the above (5) “pair comparison method experiment with test sound for each model or mode (modified method of Scheffe's pair comparison method”), The probability that each sound is uncomfortable when the two sounds are compared is obtained. More specifically, A sound (sound previously presented) and B sound (sound presented later) are compared, and a value obtained by dividing the number of uncomfortable sounds by the total number of subjects is calculated. For example, in the case where there are 40 subjects, 30 people judge that A sound is uncomfortable by comparing A sound (pre-presented sound) and B sound (post-presented sound), and B sound is uncomfortable. Assuming that there are 10 people who are determined to be, the probabilities that the A and B sounds at this time are uncomfortable are obtained as follows.
A sound discomfort probability = 30/40, B sound discomfort probability = 10/40

  Table 12 shows a part of the difference between the scores calculated as described above and the psychoacoustic parameter values (analysis data of the difference model). Table 12 shows a part of the results for the test sound of “Color 28 ppm 1-9”.

  The calculation of the difference between the subjective evaluation values and the difference between the psychoacoustic parameters, that is, the difference between the psychoacoustic parameter values of the test sound 1 and the test sound 2 (see Table 11) in the above example, Sound combinations (72 patterns per experiment, 648 patterns of the nine experiments in Tables 2 to 10 and 56 patterns tested using other machines, so a total of 704 patterns) are calculated. At that time, if it was determined that one of the sounds was unpleasant in the paired comparison experiment, the measurement of the magnitude of the discomfort difference was overscaled and could not be measured. Excluded. As a result, 638 different difference data were obtained.

(8) Deriving a formula for predicting the uncomfortable probability between two sounds The prediction formula based on neural network analysis becomes difficult to handle as the number of hidden layer units increases and the number of parameters that must be input increases. Therefore, this time, a model equation for deriving the uncomfortable probability of the printer sound was derived using a relatively simple acoustic physical quantity with the number of hidden layer units limited to one.

FIG. 51 is an example of a neural network that predicts the discomfort probability of a printer sound when the number of units in the hidden unit layer is 1.
The sound pressure level, loudness, sharpness, tonality, and impulsiveness were used as the acoustic physical quantities for the input variables that predict discomfort. The acoustic physical quantity is not limited to this, and may be adjusted by including other acoustic physical quantities.
In order to investigate the stability of the model, 30 trials were performed. The standard deviation σ of the error of the results of 30 trials and the average value of the estimated values of the parameters are shown in Table 13.
As a result, it was found that the estimated value of the parameter takes a close value although it varies depending on the trial, and R ² of each trial does not change. Therefore, this model was found to be stable.

FIG. 52 is a result of the neural network analysis, which is a result of graphing the relationship between the input acoustic physical quantity difference and the output discomfort probability at the center of each psychoacoustic parameter difference = 0. From FIG. 52, it can be seen that if the difference in acoustic physical quantity is large, the probability of discomfort increases, and in the case of the neural network analysis, it is difficult to physically interpret the parameters, but this neural network model is It turned out to be a reasonable result.
If the sound element corresponding to each acoustic physical quantity is reduced, that is,
・ Reduce the sound pressure level,
・ Reduce the amount of hearing (loudness),
・ Reduce high-frequency components (sharpness),
・ Reduce the pure tone component (tonality)
・ Reduce the impact sound (impulsiveness)
It has been found that discomfort can be reduced.
Therefore, the following formula | equation was derived | led-out here using the parameter average value of 30 trials.

By inputting the psychoacoustic parameter values of the two sounds as described above, the sound quality evaluation formula (g) that can predict the unpleasant probability when comparing the two sounds can be derived.
Here, FIG. 53 shows a scatter diagram of measured values of discomfort probabilities when a pair of two sounds are compared and predicted values derived using the above model formula. As shown in the figure, the contribution rate of discomfort is as high as 84%, indicating that the reliability of this model formula is high.

(9) Derivation of sound quality evaluation formula for predicting sound discomfort probability In the model derived as described above, it is possible to predict the discomfort probability when comparing two sounds, but this is ultimately necessary in sound quality evaluation. Is the discomfort probability of a single sound. Therefore, the sound quality capable of obtaining the relative discomfort probability in the population for a certain extracted sound from the model for predicting the discomfort probability when the two sounds are compared as follows. The evaluation formula was derived.

  First, an overall average value (see Table 11) of each test sound used in the experiment as each psychoacoustic parameter is substituted into the above equation (g), and the unpleasant probability p = 0.5 at that time, that is, The probability of discomfort when the sound when each parameter value is average was compared with other sounds of the population was defined as 50%.

Average sound pressure level = 53.20447531
Average loudness = 7.672124521
Average sharpness value = 2.318540442
Tonality average = 0.094018723
Impulsiveness average value = 0.550099991

Substituting these average values into the first equation of equation (g) to obtain H1,
0.5 = (0.975467197−3.478346509 × H1) × 0.246207214 + 0.673778545
H1 = 0.483358833
Substituting this H1 into the second equation of equation (g) to obtain z,
1 / (1 + exp (-z)) = 0.483358833
z = −0.066589263
That is, when the average value of the acoustic physical quantity is input, the intercept may be set in the equation of z so that z = −0.066589263. Therefore, the third expression of the expression (g) is transformed as follows:

z = −1.15114874
−0.942323095 × {(Sound pressure level i−1.960862153) /3.512899468)}
−0.798796482 × {(Loudness i−0.874143464) /1.729794703)}
-0.803986484 × {(Sharpness i-0.142615233) /0.532633662)}
−0.369146333 × {(Tourity i−0.001250576) /0.05706103)}
-0.833354743 × {(Impulsiveness i-0.023534937) /0.19504408)}

  By substituting the average value of the acoustic physical quantity into this equation and calculating the intercept, the intercept = 2.95298603 can be derived.

z = −0.066589263
= −1.15114874
−0.942323095 × {(53.20447531−1.960862153) /3.512899468)}
−0.798796482 × {(7.672124521−0.874143464) /1.729794703)}
−0.803986484 × {(2.318540442−0.142615233) /0.532633662)}
−0.369146333 × {(0.094018723−0.001250576) /0.05706103)}
−0.833354743 × {(0.550099991−0.023534937) /0.19504408)} + section

  Therefore, it can be converted into a model formula (d) that predicts the probability of feeling uncomfortable with a single test sound.

This time, the average value of all data was used as the reference value, but it is possible to change the reference value due to environmental changes. It is also possible to calculate the uncomfortable probability of the sound generated by the image forming apparatus after improvement using the psychoacoustic parameter value obtained from the sound of the image forming apparatus before improvement as a reference value.
The above equation (d) derived as described above estimates the change in the probability of superiority or inferiority due to deviation from the average value, and the probability when the average value of the physical quantity of sound is input is 0.5. I'm calculating. As this probability increases, discomfort increases. By using this sound quality evaluation formula, the condition of the psychoacoustic parameter where the probability P is equal to or less than a predetermined probability can be obtained.

Note that it is very difficult to test all the test sounds of a plurality of models and a plurality of modes by the conventional paired comparison method of Scheffe (a modified method of Ura). This is because Scheffe's paired comparison method (Ura's modified method) requires a pairwise comparison of the round-robin combinations of the test sounds.
For example, as in the present experimental example, there are 8 experiments with 9 sound samples and 1 experiment with 12 sound samples. In the experiment with 12 test sounds, since the sound is taken out of the 9 sound experiments, it is not a new test sound, so it is excluded and the number of test sounds is 9 × 8 = 72. In other words, you have to make a pair comparison with a round-robin combination of 72 sounds.
72 x 71 = 5112
A street comparison needs to be made, but this is virtually impossible. Here, since ninety-eight comparative experiments are performed, there are 648 comparisons, and the load on the subject is extremely small.
In addition, in the conventional Scheffe method, when it is desired to perform evaluation by incorporating a new test sound, a brute force combination experiment is required again.

However, in this method, a pairwise comparison is made with a brute force combination of test sounds (for example, nine sounds) of a new machine, and the difference data may be analyzed in addition to the previous data.
This method needs to derive the sound quality evaluation formula based on the difference data, and derive the sound quality evaluation formula for the single sound using the overall average value. There is.

  Note that, as described in (8) above, the coefficient of the neural network acquired as a result of the neural network analysis of 30 trials shown in Table 13 can take a range of twice the standard deviation (2σ). Along with this, the intercept range also becomes a value obtained by substituting the upper limit value and the lower limit value of the coefficients of each neural network. Table 14 shows a summary of the average value of each parameter and the lower and upper limits of the parameter.

  When the above equation (d) is modified assuming that the coefficient and the intercept can be taken within this range, the following equation (a) is obtained, and this equation (a) is used as a sound quality evaluation equation for predicting the unpleasant probability P. it can.

(10) Verification of the derived sound quality evaluation formula Next, the prediction accuracy of the prediction formula (sound quality evaluation formula) for the uncomfortable probability P derived as described above was verified.
This verification was performed by comparing the actual measurement value of the discomfort probability P with the predicted value derived using the sound quality evaluation formula (d). The actual measurement values of the uncomfortable probability P are the above eight experiments (“color 28 ppm”, “color 14 ppm”, “monochrome 38 ppm”, “mode mix”, “monochrome 20 ppm”, “monochrome 27 ppm”, “monochrome 65 ppm”, “monochrome” In addition to obtaining actual measurement values of discomfort probabilities from the results of “Mix”), predicted values corresponding to these values were derived using a sound quality evaluation formula.

  As the actual value of the discomfort probability, a value obtained by dividing the sum of the discomfort index of each test sound by the overall evaluation number is used. More specifically, from Table 12, in the experiment on the test sound of “color 28 ppm 1 to 9”, the denominator of the discomfort probability is the following value. When the experiment is performed by 35 people, each of the 9 test sounds is compared with the other 8 sounds, so that 8 sounds × 2 (replacement of comparison order) × 35 people = 560 people.

On the other hand, the numerator will be described by taking the test sound 1 of “color 28 ppm 1 to 9” as an example, and it is determined that the test sound 1 is uncomfortable when compared with other test sounds 2 to 9 (including reverse order). The total number of persons who were 10 (test sound 1-test sound 2 and I was uncomfortable 2 persons, test sound 2-test sound 1 and J was unpleasant 8 persons, and so on), 20 people, 20 If people, 19, 19, 50, 5, 5, and 5 people, the sum of 148 people is the numerator.
Therefore, in this case, the actual measurement value of the uncomfortable probability of the test sound 1 in the “color mode 1” is 48/560 = 0.26.

  In the above procedure, an actual measurement value of the probability of discomfort is obtained for each test sound of each of the eight experiments, and a predicted value is obtained by substituting the physical quantity of sound (psychoacoustic parameter) into the sound quality evaluation formula (d). obtain. Table 15 shows the measured discomfort probability and Table 16 shows the predicted discomfort probability by the neural network as a result of obtaining the actually measured discomfort probability and the predicted probability for each test sound in each mode.

FIG. 54 shows each of eight experiments (“Color 28 ppm”, “Color 14 ppm”, “Monochrome 38 ppm”, “Mode Mix”, “Monochrome 20 ppm”, “Monochrome 27 ppm”, “Monochrome 65 ppm”, “Monochrome Mix”). FIG. 5 is a graph in which values predicted using the above formula (d) (horizontal axis) and measured values (vertical axis) are compared and plotted. The experiment of comparing the six sounds related to the image forming apparatus having a plurality of modes (color 14 ppm, color 28 ppm, monochrome 38 ppm) and the six sounds related to the image forming apparatus having the monochrome single mode shown in Table 10 is as follows. Since it is not a comparison of brute force combinations, the relative discomfort probability of 12 sounds cannot be calculated. For this reason, it was not possible to plot on the graph.
As shown in FIG. 54, the overall slope of this graph is 0.98, which is almost 1, and the overall contribution rate is 93%. Therefore, in any of the eight experiments, it is considered that the accuracy of the predicted value of the score derived by the above equation (a) is high.

  In deriving a predicted value for verification, an intercept (= F) is obtained from the average value of psychoacoustic parameters for each experiment (each mode), and an equation obtained by slightly modifying the equation (d) using the intercept as an intercept is obtained. Derived for each mode, the predicted value was determined using the derived formula. Such adjustment was performed because it was necessary to verify the accuracy of the predicted value by comparing the measured value and the predicted value of each experiment. An actual measurement value of the discomfort probability is obtained by each of the eight experiments, because this is the discomfort probability that holds for each experiment. When the verification is not performed, the above formula (d) can be used as the sound quality evaluation formula without performing such adjustment. Table 17 shows the adjustment values for reference. When the value of “difference from the overall average” is added to the value of the intercept obtained by substituting the average value of each mode, the same expression as the above expression (d) is obtained.

  Now, it is considered that the accuracy of the predicted value (evaluation) obtained by the equation (d) derived as described above is high, but when the discomfort probability P, which is the evaluation obtained in this way, becomes a value, the person is uncomfortable. It is important to stop feeling. Therefore, the following experiment was conducted to confirm this.

For the test sound of 14ppm color, 28ppm color, 38ppm monochrome, 65ppm monochrome, the subjects asked all the test sounds 1-9 for each speed experiment, and then listened to each sound again. An experiment was conducted to evaluate the uncomfortableness of the test sound in three stages.
Since the test sound of 65 ppm monochrome was larger between the test sound 1 and the test sound 5 than the interval between the other sounds, it was created in advance between the test sound 1 and the test sound 5. Unevaluated sample sounds 10 and 11 were prepared. Table 22 shows the physical quantities of the test sounds 10 and 11. As a result, the results shown in Table 18 to Table 22 were obtained.

  In the table, “A” is an acceptable sound, “C” is an unacceptable sound, and “B” is an intermediate sound. Of the sound quality evaluation values of the sound evaluated as “A” (values calculated by the equation (d)), assuming that the maximum value is an allowable value, ppm of each experiment and image formation speed (mm / s) The allowable value for each is as shown in Table 23.

  FIG. 55 is a graph in which the relationship between the ppm value and the allowable value is approximated based on the results shown in Table 21. The approximate expression is

It is. The contribution ratio representing the accuracy of this equation is R ² = 0.86.
FIG. 56 is a graph in which the relationship between the image forming speed (mm / s) and the allowable value is approximated based on the results shown in Table 21. The approximate expression is

It is. The contribution ratio representing the accuracy of this equation is R ² = 0.89.
As shown in Table 21, if the discomfort probability P calculated from the sound generated when operating at each speed (ppm or image forming speed mm / s) is less than or equal to an allowable value, the discomfort is hardly felt. .

As described above, by using the above formula (d), (c), or formula (a), a psychoacoustic parameter value that can be obtained from a physical quantity of sound can be obtained without actually performing a subjective evaluation experiment. The discomfort index S, which is an evaluation of discomfort, can be obtained simply by doing.
Even if the apparatus has a plurality of operation modes having different image forming speeds (mm / s and ppm) and the image forming apparatus has different image forming speeds according to the above formulas (b) and (d), It is possible to determine what value the discomfort probability P obtained for each item does not cause discomfort.
The method for evaluating the quality of sound emitted from the image forming apparatus and the method for deriving the sound quality evaluation formula used for the sound quality evaluation have been described above.

(C) Remodeling method As described above, the present invention is a remodeling method that evaluates noise generated by the image forming apparatus as described above and takes measures to reduce discomfort caused to the person by the noise based on the evaluation. In the following, a specific example of measures for modifying the image forming apparatus having the above-described configuration to reduce the sound generated by the image forming apparatus from causing discomfort to humans will be described.

  First, in order to evaluate the sound emitted by the image forming apparatus, the sound emitted by the image forming apparatus is collected by the same method as the above-described (1) “collecting operation sound of the image forming apparatus”. Here, the sampling position is the position of the neighbor specified in ISO 7779 (see FIG. 17), the distance is 1.00 ± 0.03 m from the projection of the horizontal plane of the reference box, and the height is 1.2 ± 0.03 m or 1.50 above the floor. The position is ± 0.03m.

Further, as shown in FIG. 15, sounds are collected on all four sides such as the front, left and right sides and rear side where the operation unit is provided, and psychoacoustic parameters are obtained from the respective sound collection results to obtain the discomfort probability P as the sound quality. It may be determined by an evaluation formula to determine whether or not the discomfort probability P for each surface is within an allowable value, or the discomfort probability P from the sound collection results collected only on the front surface or only one surface side. You may make it determine by calculating | requiring.
Alternatively, an average value of psychoacoustic parameter values obtained from sounds collected on the four sides may be derived, and it may be determined whether or not the discomfort probability P obtained from the average value is within an allowable value.

  In order to prevent people on any of the four sides from feeling uncomfortable, it is preferable to collect sound at all positions on the four sides. Satisfactory evaluation can also be made by collecting sound on the front side, which has high characteristics.

  When the discomfort probability P obtained as described above exceeds the above-described allowable value, there is a high possibility that the person feels uncomfortable, so each part of the apparatus is set so that the discomfort probability P is equal to or less than the allowable value. Various modifications are made to. On the other hand, when the uncomfortable probability P is less than or equal to the allowable value, it can be determined that there is little possibility that a person will feel uncomfortable and that it is not necessary to take measures against noise.

  As described above, the uncomfortable probability P decreases the sound pressure level, reduces the volume of hearing (loudness), reduces high frequency components (sharpness), reduces pure sound components (tonality), and reduces the impact sound. By taking measures such as (impulsiveness), it can be reduced, and by reducing this, discomfort given to people can be reduced. Therefore, a specific countermeasure example for reducing the psychoacoustic parameters will be described below.

(1) Measures for reducing tonality (pure sound component) ◆ Image forming apparatus having a plurality of modes (1-1) Reduction of drum driving stepping motor sound First, an example of measures for reducing tonality will be described. As a measure for reducing tonality, there is a method of reducing drum drive stepping motor sound. As shown in FIGS. 16, 17, and 18, the drum drive motor generates sound in any of the operation modes. And this sound contains many frequency components of the input pulse to the stepping motor.

57 and 58 are diagrams showing a drum drive mechanism including a color drum drive motor 41 and a black drum drive motor 42 before modification. As shown in these drawings, the color drum drive motor 41, the black drum drive motor 42, and the gears 43 and 44 are held by a motor bracket 59.
The motor bracket 59 is a member obtained by giving strength to a sheet metal by drawing or the like. A housing attachment portion (screw hole or the like) of the image forming apparatus is formed by bending, and the motor bracket 59 is fixed to the housing at this attachment portion.

  Four gears 44 arranged side by side are rotatably held by the motor bracket 59. Of these gears 44, the rightmost gear 44 in FIG. 57 and the gear 61 attached to the motor shaft of the black drum drive motor 42 are engaged with each other. As a result, the gear 44 is rotated by the black drum drive motor 42, and the photosensitive drum 28 (see FIG. 3) for forming a monochrome image is rotated accordingly.

Of the three gears 44 other than the gear 44 described above, the two left-side gears 44 in FIG. 57 are rotated by the motor shaft 62 of the color drum drive motor 41.
Further, the second gear 44 and the third gear 44 from the left are both meshed with the relay gear 43, whereby the third gear 44 is rotated with the rotation of the second gear 44. That is, with the rotation of the color drum drive motor 41, the three gears 44 are rotated, whereby the C, M, and Y photoconductive drums 28 (see FIG. 3) are rotated simultaneously. Yes.

  The gear for driving the photosensitive drum as described above adopts a special anti-vibration structure etc. for the motor installation so that the distance between the shafts of the gear can be accurately adjusted to the design value with module 0.5. Not done. That is, the black drum drive motor 42 and the color drum drive motor 41 are directly attached to the motor bracket 59 and fixed.

  By directly attaching the motor to the motor bracket 59 in this way, the vibration of the motor during operation propagates to the motor bracket 59 solidly and is amplified and radiated. The sound generated due to this is a sound containing a lot of driving frequency components of the stepping motor which is a drum driving motor.

  In order to reduce the generation of such a sound with a significant driving frequency component of the stepping motor, as shown in FIG. 59, the color bracket driving motor 41 and the black drum driving motor 42 are connected to a motor bracket 65 via a vibration-proof rubber mount 60. To be attached to. That is, the anti-vibration rubber mount 60 serves as a reduction means for reducing the sound generated as described above.

  As the anti-vibration rubber mount 60, for example, a stepping motor mount manufactured by NOK Co., Ltd. can be used, and the stepping motor mount is used in a test to test the effect of noise countermeasures described later.

A drum drive mechanism in which an anti-vibration rubber mount 60 is interposed between the motor bracket 65 and the drum drive motor will be described with reference to FIGS.
If the anti-vibration rubber mount 60 is interposed between the drum drive motor and the motor bracket 65, the accuracy of the inter-shaft distance of each gear deteriorates. For this reason, this drum drive mechanism is configured to transmit the driving force from the motor shaft to the gear 44 and the like via the timing belt mechanism, instead of directly engaging the motor shaft with the gear.

  More specifically, timing pulleys 66 and 67 are attached to the motor shafts of the color drum driving motor 41 and the black drum driving motor 42, respectively, and a two-stage gear / motor is driven by the timing belt 70 wound around the timing pulleys 66 and 67. The driving force of the motor is transmitted to the pulleys 63 and 64. That is, the two-stage gear / pulleys 63 and 64 are rotated with the rotation of the motor shaft.

  The two-stage gear / pulley gear is engaged with the drum driving gear 44 described above. As a result, the gear 44 can be rotated in accordance with the rotation of the drum drive motor, and the photosensitive drum 28 (see FIG. 3) can be rotated, as in the configuration before the remodeling.

  The motor bracket 65 is bent so that the portion that holds the motor (the lower portion in FIG. 61) protrudes to the opposite side of the motor from the upper portion. The anti-vibration rubber mount 60 is arranged in contact with the motor bracket 65 in the space formed in the protruding portion, and the motor (41, 42) on the opposite side of the anti-vibration rubber mount 60 from the motor bracket 65 has its motor shaft mounted on the motor bracket 65. Are arranged so as to protrude from the surface on the opposite side (left side in FIG. 61). As described above, the structure is such that the motor bracket 65 and the motor are not directly held, but are held with the anti-vibration rubber mount 60 interposed therebetween.

  In this configuration, the two-stage gears / pulleys 63 and 64 are arranged on the left side of the motor bracket 65 in FIG. 61 (the side on which the gear 44 is arranged), so that the motor shaft protrudes to the left side in FIG. It is necessary to let However, by forming a protruding portion on the motor bracket 65 as described above, the motor arrangement position itself can be on the left side of FIG. 61, thereby eliminating the need to lengthen the motor shaft. Therefore, it is possible to suppress the eccentricity of the motor shaft that may be caused by lengthening the motor shaft and the generation of noise caused by the eccentricity.

  In this configuration, it is preferable to increase the strength of the stud 69 for attaching the two-stage gear / pulleys 63 and 64. When the strength of the stud 69 is insufficient, the gear 44 and the two-stage gears / pulleys 63 and 64 mesh with each other while being eccentric, and the drum shaft 68 is also eccentric via the bearing 700. This is because the eccentricity of the drum shaft 68 may affect the image formed on the paper, and it is necessary to increase the strength of the stud 69 in order to prevent such a problem.

In addition to the above-described anti-vibration rubber mount, an elastic body that can absorb the vibration of the motor to some extent may be used.
The measures for reducing the drum driving stepping motor sound have been described above.

(1-2) Reduction of Paper Feeding Stepping Motor Sound Next, a countermeasure for reducing paper feeding stepping motor sound will be described. As described above, the sheet feeding motor of the image forming apparatus is the stepping motor 83 (see FIG. 8), and the conveyance of the sheet from the tray is performed by controlling the driving of the stepping motor. As a measure for reducing the motor noise, there is a method of setting the drive control content of the stepping motor 83 as follows, and the control content will be described.

Figure 62 is a diagram for explaining the movement of the stepping motor rotor is driven by a step angle theta _0. The step angle of the stepping motor is determined by the mechanical structure. Normally, the rotor moves at a time by such a step angle θ. Therefore, when the step angle θ is large, the movement is not smooth and vibrations occur. This causes noise.

  Therefore, in this configuration, so-called micro-step driving is performed in which the stepping motor is driven at a step angle smaller than the step angle θ determined by the mechanical structure by control by an electronic circuit as shown in the figure. That is, by performing current supply control such that the current value supplied to one phase of the excitation phase is gradually increased while the current value supplied to the other one phase is gradually decreased ((A) to 62 in FIG. 62). (See (E)), it is possible to drive at a step angle smaller than the step angle θ, and smooth the movement to reduce noise.

  FIG. 63 is a diagram showing a 1-2 phase excitation sequence which is one of microstep driving of the stepping motor. 1-2 phase excitation is an excitation method that alternately repeats one phase excitation for exciting the coil one phase at a time and two phase excitation for exciting the coil two phases at a time. When a stepping motor is driven using this excitation method, The motor step angle is halved, and the movement of the rotor is smoother than normal driving, and vibration can be reduced.

(1-3) Reduction of Polygon Mirror Motor Sound Next, countermeasures for reducing the sound generated by the polygon mirror motor will be described with reference to FIG. As shown in FIG. 64, in this measure, a Helmholtz resonator 71 is attached in the vicinity of the polygon mirror motor 2. More specifically, a Helmholtz resonator 71 is attached to the upper part of the housing 11 that holds the polygon mirror motor 2.

Helmholtz resonator 71 has a cavity forming member 72a for forming the cavity 72 of the volume V _1. The cavity forming member 72 a is formed integrally with the housing 11, and an opening hole 73 (cross-sectional area Sb) leading to the cavity 72 is formed at a portion facing the polygon mirror motor. Here, if the thickness of the portion where the opening hole 73 is formed is Tb, the opening hole 73 corresponds to a short tube having a length Tb and an opening area Sb in a general Helmholtz resonator. This structure functions as a Helmholtz resonator 71.

Under this configuration, when the polygon mirror motor 2 is driven and a sound pressure acts on the entrance of the opening hole 73 by the vibration, the air (medium) in the opening hole 73 (short pipe) performs an integral motion, and the inside of the cavity 72 This causes a pressure change in the air. Such a phenomenon is equivalent to the mass point-spring model of the dynamic system, assuming that the air in the opening hole 73 (short pipe) is a mass point and the pressure change due to the volume change of the air in the cavity 72 is a spring. Resonance (resonance) occurs with respect to the Helmholtz resonance frequency. That is, since the acoustic energy of this Helmholtz resonance frequency is confined in the cavity 72, the sound is reduced for the external space.
Here, the Helmholtz resonance frequency Fh (Hz) is calculated by the following equation.
Fh = C / 2π (Sb / (V1 · Tb)) ^1/2
C: Speed of sound

That is, (thickness of the portion where the opening hole 73 of the words housing 11 is provided) the opening area Sb, the length Tb of the opening hole 73, the resonance by changing the volume V ₁ of the cavity 72 formed by the cavity forming member 72a The frequency Fh, that is, the frequency of the sound to be reduced can be changed. Therefore, if the dimensions and the like of the above parts are designed so as to match the frequency at which the level becomes the highest among the sounds generated when the polygon mirror motor 2 is driven, the sounds generated by the polygon mirror motor 2 can be effectively obtained. Can be reduced.

  From the noise measurement results described above (see FIGS. 16 to 18), although the polygon mirror motor sound is extracted as noise in the color mode, the sound is not so noticeable as noise in the monochrome mode. . In such a case, the dimensions and the like of each part may be determined so that the Helmholtz resonance frequency matches the frequency of the highest level among the sounds generated by the polygon mirror motor in the color mode as described above. On the other hand, when the level of other frequencies is high in the monochrome mode, a Helmholtz resonator may be separately provided so that this frequency becomes the resonance frequency.

  In addition, a Helmholtz resonator may be provided for each corresponding frequency as described above, but a mechanism for changing the opening area Sb of the opening hole 73 in the color mode and the monochrome mode may be provided. . For example, by providing a lid member or the like that can be moved between a position where the opening hole 73 is blocked to some extent and a position where the opening hole 73 is not blocked, and moving the lid member according to the mode, the resonance frequency in each mode is changed to each mode. It may be varied so as to match the frequency at which the level sometimes increases.

(1-4) Reduction of Charging Sound Next, a countermeasure for reducing charging noise will be described. The charged sound is sound generated as follows. That is, when the charging roller 36 charges the photosensitive drum 28 (see FIG. 3), the attractive force is generally generated between the surface of the charging roller 36 and the surface of the photosensitive drum 28 due to the AC component of the bias voltage. Repulsive forces act alternately, causing vibration between them. The sound radiated from the photosensitive drum 28 by this vibration is a charging sound, and the sound is an unpleasant pure sound with a high frequency, and is generally an AC component frequency and an integral multiple frequency component (harmonic component). Consists of.

  Such measures for reducing the charging noise will be described with reference to FIGS. 65 and 66. FIG. As shown in FIG. 40, a vibration damping member 74 is disposed in the hollow portion of the photosensitive drum 28 that has been subjected to charging noise countermeasures. The damping member 74 has a hollow cylindrical base portion 75 extending in the axial direction of the photosensitive drum 28 and a plurality of blade portions 76 projecting radially from the base portion 75, and the central axis of the base portion 75 is photosensitive. It arrange | positions so that it may correspond with the center axis | shaft of the body drum 28 substantially.

The tip of each blade portion 76 of the vibration damping member is in pressure contact with the inner surface of the photosensitive drum 28, whereby the vibration damping member 74 is held in the photosensitive drum 28. Here, it is preferable that the blade | wing part 76 is comprised with elastic materials, such as thermoplastic resin materials, such as rubber | gum, resin, or the material containing these, for example, the material containing urethane rubber, a polypropylene resin, a polyamide resin.
By using an elastic material as the blade portion 76, the tip of the blade portion 76 is pressed against and held by the photosensitive drum 28 by its elastic force. This eliminates the need for a bonding operation or a positioning operation using an adhesive or the like, and facilitates an attachment operation and a removal operation.

As described above, the vibration damping member 74 is arranged so that the blade portion 76 is in pressure contact with the inner surface side of the photosensitive drum 28, so that the vibration damping member 74 acts to suppress vibration of the photosensitive drum 28.
Accordingly, it is possible to suppress vibration of the photosensitive drum 28 that occurs during charging by the charging roller 36 described above. In addition, since the member for suppressing the vibration of the photosensitive drum 28 is installed inside the photosensitive drum 28 as described above, it is not necessary to take measures such as newly taking a space for installing the damping member. .

  The means for suppressing the vibration of the photosensitive drum 28 to reduce the noise is not limited to the vibration damping member 74 having the above-described configuration, and measures such as fitting a metal column into the hollow portion of the photosensitive drum 28 are taken. Alternatively, a commercially available damping material (for example, a rubber damper manufactured by Yokohama Rubber Co., Ltd.) may be attached.

◆ Desktop type (desktop) image forming apparatus As shown in FIG. 19, AC charging sound is also generated in the desktop type (desktop) image forming apparatus. Also in this case, the above-mentioned means can suppress the generation of AC charging noise.

(2) Measures for reducing sharpness (high frequency component) ◆ Image forming apparatus having a plurality of modes (2-1) Reduction of paper sliding noise Next, measures for reducing sharpness (high frequency component) will be described. As a measure for reducing sharpness, there is a method of reducing paper sliding noise. Note that the paper sliding noise is a sound generated when the conveyed paper slides with a member or the like.

  As described above, the sheets stored in the first tray 9 or the second tray 10 of the image forming apparatus having a plurality of modes are fed out from each tray by the first sheet feeding unit 51 or the second sheet feeding unit 52 and relayed. It is conveyed to the position of the registration roller 7 by the roller 53 and the conveying roller 55 (see FIG. 7).

  Here, FIGS. 67A and 67B show a case where the paper stored in the first tray 9 or the second tray 10 is conveyed to form an image (during normal printing) and a case where printing is performed without conveying the paper (free). The result of frequency analysis (1/3 octave band analysis) by measuring the noise generated by the image forming apparatus is shown. FIG. 68 is a graph showing a difference in sound pressure level in each frequency band obtained from normal printing and free-running noise shown in the analysis result.

  That is, the sound pressure level for each frequency band shown in FIG. 68 is a difference in noise content generated by the image forming apparatus due to whether or not the sheet is sent out from the first tray 9 or the second tray 10 and conveyed. It means that the sound pressure level is increased in each frequency band as shown in FIG. 68 by conveying the paper.

  From the graph shown in FIG. 68, there are two differences of 3 (dB) or more between normal printing and free running in a band centering on 200 to 250 Hz and a band of 3.15 kHz or more. . Note that the difference of 3 dB or more means that the acoustic energy is twice or more.

Examining the above analysis results, it has been found that the band component centered at 200 to 250 Hz is caused by the sound generated when the sheet and the registration roller 7 collide.
On the other hand, it was found that the component in the frequency band of 3.15 kHz or more is caused by the sound generated when the paper slides on the member or the like during paper conveyance.
Further, in the band centering around 12.5 kHz to 16 kHz, there is a difference of 7 (dB) or more, and this band has a great influence on the sharpness value. From this, it can be seen that reducing the sheet sliding noise is effective as a noise countermeasure.

Hereinafter, a countermeasure for reducing the sliding noise of the sheet conveyed by the sheet feeding unit, the relay roller 53, and the conveying roller 55 will be described with reference to FIG.
As shown in FIG. 69, the conveyance roller 55 is a roller that has a plurality of rollers passing through its shaft, and includes a roller 55a and a roller 55b that are disposed to face each other with the sheet conveyance path interposed therebetween. Then, the sheet 55 conveyed along the conveyance path A (the sheet fed out from the first tray 9) or the sheet conveyed along the conveyance path B (the sheet fed out from the second tray 10) is the roller 55a. , 55b and conveyed toward the registration roller 7 by rollers 55a, 55b.

Guide members 80, 81, 82 for conveying the paper along a predetermined path are disposed in the vicinity of the conveyance roller 55.
The guide member 80 forms a space for guiding the paper conveyed along the conveyance path A together with the rollers 55a between the rollers 55a and 55b. The guide member 80 forms a space for guiding the sheet conveyed along the conveyance path B together with the guide member 81 toward the rollers 55a and 55b.

  A guide member 77 made of a treadable sheet (for example, a mylar sheet) extending in the paper transport direction (vertical direction in the figure) is attached to the downstream side of the guide member 80 in the transport direction (upper side in FIG. 69). The guide member 77 guides the sheet conveyed from the conveying paths A and B toward the rollers 55a and 55b.

  As shown in FIG. 70, at the position where the roller 55a is arranged so as not to intersect with the roller 55a at the front end portion of the guide member 77, a notch portion 77a is formed by cutting or the like. The tip is brought into contact with the roller 55a and 55b so as to be surely guided.

  Therefore, as shown in FIG. 71, the sheet from the conveyance path A is conveyed while sliding on the leading end portion of the guide member 77. The conventional general guide member 77 is manufactured by shearing a flexible sheet into a predetermined shape, and a burr is usually provided at the tip portion (shear portion). It is very difficult to remove such burrs one by one, which requires cost and time. Therefore, normally, such an operation is not performed, and an awkward noise is generated by the sliding of the front end portion with the burr and the paper.

  Therefore, in this configuration, by employing the guide member 77 having the configuration shown in FIG. 72, it is possible to reduce annoying noise caused by the sliding of the paper and the leading end portion of the guide member 77 as described above. .

  As shown in FIG. 73, a conventional guide member made of a flexible sheet uses a flexible sheet having a thickness t sheared into a predetermined shape as it is as a guide member 77, and the leading edge on which the paper slides. The part is a sheared part. On the other hand, in the configuration shown in FIG. 72, a flexible sheet having a thickness of t / 2 is folded to overlap two sheets so that the bent portion becomes the tip portion of the guide member 77. By adopting the guide member 77 having such a configuration, the leading end portion on which the sheet conveyed as described above slides is a bent portion, a portion not subjected to shearing, and a smooth R shape. Become.

  Therefore, it is possible to reduce generation of annoying noise caused by burrs in the sheared portion as described above. Further, since the thickness of the two stacked sheets is the same as that of the conventional guide member 77, the required elastic force can be exhibited and the function as the guide member is not hindered.

◆ Large-sized (console-type) image forming apparatus An example of reducing paper sliding noise will be shown for a large-sized (console-type) image forming apparatus.
First, the configuration of the conveyance path, which is the sound source of the paper sliding sound, and the cause of occurrence will be described. FIG. 74 is an explanatory diagram showing a detailed configuration of the rollers and guide plates of the main body vertical conveyance unit 580 in the image forming apparatus shown in FIG. That is, it is a cross-sectional view of a conveyance portion that guides conveyance from a paper feed tray and conveyance from an intermediate tray for double-sided copying in the direction of a registration roller. FIG. 75 is an explanatory diagram showing the relationship between the recording paper and the flexible sheet 559 when noise is not taken.

  In FIG. 74, a pair of rollers 550 and 551 having a plurality of rollers arranged on a shaft as a pair is used as a first transport roller pair for transporting the recording paper, and the recording paper transported from the paper feed tray is illustrated in FIG. Rotate to transport in the direction. In addition, among rollers 552, 553, and 554 having a plurality of rollers arranged on a shaft, a pair of rollers 552 and 553 is formed to form a second conveyance roller pair that conveys the recording paper, and is conveyed from the intermediate tray. The recording paper is rotated so as to be conveyed in the direction B shown in the figure. Further, the roller 552 and the roller 554 are paired to form a third transport roller pair for transporting the recording paper, and the roller 552 and the roller 554 are rotated so as to transport in the C direction in the drawing, that is, the registration roller direction.

  Guide plates 555 and 556 are provided in the conveyance path of the first conveyance roller pair that is rotated so as to convey in the direction of arrow A, and the guide plates 555 and 556 have roller portions of the rollers 550 and 551. There is a hole to escape. Similarly, guide plates 557 and 558 are provided in the conveyance path of the second conveyance roller pair that rotates so as to convey in the direction of arrow B. The guide plates 557 and 558 are provided with rollers 552 and 553. There is a hole to escape the roller. Further, in the conveyance path of the third conveyance roller pair that rotates so as to convey in the direction of arrow C, there are extended portions of the guide plates 556 and 557, and these run away from the roller portions of the rollers 552 and 554. There is a hole in. That is, the conveyance force by the conveyance roller pair and the conveyance performance by the guide plate are ensured.

  A flexible sheet 559 extending in the recording paper conveyance direction is attached to the downstream end portion of the guide plate 555, and is provided so as to guide the recording paper. A conveyance path is formed so that the recording paper conveyed from the A direction is also conveyed in the C direction.

  Here, the recording paper conveyed in the B direction from the intermediate tray often has a downward curl, and in order to prevent the occurrence of folding or jamming (paper jam), a flexible sheet (specifically, Polyester film, product name: Mylar) 559 is bent in the right direction in the figure. Accordingly, the recording paper conveyed in the A direction from the paper feed tray enters between the rollers 552 and 554 by bypassing the front end of the flexible sheet 559.

  At this time, in the case of an unmeasured flexible sheet 559 as shown in FIG. 75, the recording paper is conveyed while sliding the tip of the flexible sheet 559. However, since the surface of the recording paper has fiber irregularities, and the flexible sheet 559 has burrs on the end surface due to shearing processing, the irregularities progress on the fibers on the recording paper surface, so that the flexible sheet The burr at the edge portion of 559 and the recording paper vibrate and generate a loud noise, resulting in noise. Note that it is very costly and time-consuming to remove burrs at the edge of the flexible sheet 559 one by one. Therefore, as shown below, countermeasures for reducing paper sliding noise were made by devising the flexible sheet 559.

76 and 77 show examples of the flexible sheet 559 according to the embodiment of the present invention. Note that this is the same as in the case of an image forming apparatus having a plurality of modes.
76 and 77, the leading edge of the flexible sheet 559 attached to the guide plate 555 slides when the recording paper conveyed from the direction of arrow A in FIG. In order to reduce (the surface of the paper has a certain degree of surface roughness and a sound containing a lot of high frequency components is generated when the edge is slid), a bent portion 559a is formed. The surface of the flexible sheet 559 is extremely smooth, and even if the bent portion 559a is provided, the smoothness is not lost.

(3) Measures to reduce impulsiveness (impact component) ◆ Image forming apparatus having a plurality of modes In the image forming apparatus having the above-described configuration, the occurrence of impulsiveness is mostly caused by fixing oil application sound (see FIG. 16 to FIG. 18). In the image forming apparatus configured as described above, the fixing oil application sound is configured to drive the oil application unit 47 and contact the fixing belt 13 each time a sheet is conveyed in order to suppress an increase in oil consumption. Adopted (see FIG. 6). Since such a contact / separation sound generated every time the sheet is conveyed is generated shockingly, it causes discomfort.

  The noise problem due to the fixing oil application sound can be solved by using an oilless toner as a toner used for image formation. That is, since the oil-less toner includes wax in the toner, the separation between the fixing belt and the paper is good without performing the oil application operation as described above. For this reason, it is not necessary to use the oil application unit 47, and it is possible to prevent the generation of impact sound due to the contact and separation between the oil application unit 47 and the fixing belt 13 described above. When using oilless toner, it is necessary to modify the image forming process configuration of the photoconductor unit 3 and the like so as to be suitable for the oilless toner.

◆ Large-sized (console type) image forming apparatus FIG. 78 is an explanatory diagram showing the configuration of the paper feed / drive system of the bank paper feed unit 570 in FIG. As shown in FIG. 13, the image forming apparatus in this embodiment is configured to be capable of four-stage paper feeding, and the upper stage makes the conveyance path shorter, so that image formation becomes quicker. Therefore, frequently used A4 size recording paper is set in the first level (the top level), and the B4 and A3 sizes, which are generally used less frequently, are set in the third and fourth levels (lower level). Often, this type of recording paper is loaded.

In FIG. 78, grip rollers 567 are arranged in each of the four stages of paper feeding devices, and the recording paper fed from each paper feeding device goes upward via the grip rollers 567.
The grip roller 567 is provided with a driven roller 569 facing each other and is pressurized by a pressure spring 568. The grip roller 567 and a paper separation mechanism (not shown) are driven by a bank motor 561 and convey the recording paper to the upper portion 500.

  An intermediate clutch 562, an intermediate clutch 563, an intermediate clutch 564, and an intermediate clutch 565 are provided on each shaft of the grip roller 567 from the top. These intermediate clutches 562 to 565 are constituted by electromagnetic clutches, and grip the driving force using the bank motor 561 transmitted to the electromagnetic clutch gear via a timing belt and a gear train as the current is turned on / off. The roller 567 is rotated or non-rotated. This drive mechanism is provided in order to increase the processing efficiency by feeding the recording paper during image formation to control the space between the recording papers to the minimum. The relay sensor 566 is used for taking an image writing timing and for detecting a jam (paper jam).

  By the way, the main factor of the metal impact sound in the image forming apparatus is the operation sound of the intermediate clutch of the bank paper feeding unit 570 (the metal collision sound that the disks are attracted by the force of the electromagnet in the clutch ON operation). I know. These four intermediate clutches operate each time one sheet of recording paper is fed. In order to simplify the control, it is configured to operate even if paper is fed from any stage of the bank paper feeding unit 570. For this reason, even if paper is fed from the first stage of the bank paper feeding unit 570, the second to fourth stage grip rollers 567 that do not need to be driven are also driven. When paper is fed from the fourth stage (bottom 1), the recording paper is not conveyed upward unless all the grip rollers 567 are operated, so that all the intermediate clutches 562 to 565 need to be operated.

  However, as described above, frequently used paper is fed from the uppermost stage of the bank paper feeding unit 570 or the second tray. The third and fourth stages are used less frequently because they are loaded with recording paper having a low usage frequency.

  The metal impact noise is generated greatly when the intermediate clutches 562 to 565 of the bank paper feeding unit 570 are operated simultaneously. Therefore, when the first stage of the bank is used, only the intermediate clutch 562 is operated. The energy generation of the metal impact sound can be suppressed to ¼. In this way, by controlling so that only the intermediate clutch in the upper stage of the bank used for paper feeding is operated, it is possible to suppress noise and consumption of electric energy.

FIG. 79 is a flowchart showing an example of control of the intermediate clutch of the bank paper feeding unit 570.
First, it is determined whether or not the first-stage sheet feeding is performed. If the first-stage sheet feeding is performed (YES in step S11), the intermediate clutch 562 is operated (step S12).
If it is not the first-stage paper feed but the second-stage paper feed (NO in step S11, YES in S13), the intermediate clutches 562 and 563 are operated (step S14).

Further, if it is not the second-stage paper feed but the third-stage paper feed (NO in step S13, YES in S15), the intermediate clutches 562 to 564 are operated (step S16).
Further, when the third-stage sheet feeding is not performed, that is, the fourth-stage sheet feeding (sheet feeding from the lowest tray) (NO in step S15), the intermediate clutches 562 to 565 are operated (step S17).

  In this way, by performing control to turn on only the necessary intermediate clutch and not operating the lower intermediate clutch that is less frequently used, it is possible to suppress the occurrence of metal impact noise.

FIG. 80 is a graph showing changes in metal impact sound before and after improvement of control of the intermediate clutch. “Before improvement” means that four intermediate clutches are operated simultaneously. The metal impact sound improvement is obtained by operating only the first-stage intermediate clutch 562. According to this, the impact sound of the clutch is a high-frequency broadband noise of about 1 k to 20 kHz, and contributes not only to impulsiveness but also sharpness and loudness. In this way, the unpleasant sound can be reduced by suppressing the sound source of the impact sound.
The specific example of the countermeasure for reducing the unpleasant probability P has been described above.

  The present inventor measures the sound emitted by the image forming apparatus to which the above measures are taken under the same conditions as when the sound generated by the image forming apparatus before the countermeasure is measured, and determines the effect of the countermeasure from the measurement result. confirmed. The measurement results to be compared below are obtained by collecting sound on the front side of the image forming apparatus when the image forming apparatus is operated at a color of 28 ppm.

FIG. 81 shows the noise analysis results after the countermeasures. Comparing the analysis result after the countermeasure shown in the figure with the analysis result before the countermeasure (see FIG. 10), the paper feeding stepping motor noise is reduced by about 10 (dB), the charging noise is about 5 (dB), and the drum drive The motor sound is reduced by about 8 (dB), and the polygon mirror motor sound is also reduced by about 10 (dB).
In addition, the fixing oil application sound was eliminated. From the above, it can be seen that the sound produced by each sound source can be reduced by taking the above measures.

82 to 85 further compare the frequency distributions in the four directions before and after the countermeasures.
The pure tone component is reduced in each direction. In addition, although the cause is unknown in four directions, 400Hz rose.
Table 24 shows a comparison result of the psychoacoustic parameter value obtained from the measurement result before the countermeasure and the uncomfortable probability P based on the sound quality evaluation formula (d).
Table 25 shows a comparison result of the psychoacoustic parameter value obtained from the measurement result after the countermeasure and the discomfort probability P based on the sound quality evaluation formula (d).

  As can be seen from these tables, the value of the discomfort probability P is lower after taking countermeasures for the average values in each direction and the four directions. Also,

P ≦ 0.3194Ln (ppm) −0.7472 ・ ・ ・ ・ ・ ・ （b）
Or P ≦ 0.2831Ln (v) −1.0675 ・ ・ ・ ・ ・ ・ (e)

Therefore, the allowable value of the discomfort probability P at 28 ppm (125 mm / s) is 0.32 in the case of the formula (b), and 0.30 in the case of the formula (c). Only the right surface exceeded the allowable value, but the average values in the other directions and the four directions were smaller than the allowable value.

  Therefore, the image forming apparatus has been remodeled so as to cause almost no discomfort except for the right side by the above measures, and it can be said that the image forming apparatus hardly feels discomfort considering the average values in the four directions. Further, from the results shown in FIGS. 82 to 85, further improvement in sound quality can be expected by reducing 400 Hz for which the cause is unknown, and it is possible to set the value to the allowable value or less on the right side.

(D) Application example of the present invention Note that the present invention evaluates the sound quality of the image forming apparatus using the sound quality evaluation formula derived as described above so that the evaluation result (discomfort probability P) satisfies a predetermined condition. Therefore, an image forming apparatus can be provided. Therefore, as shown in FIG. 86, the present invention can be applied when developing and manufacturing a new product.
Specifically, what kind of configuration is adopted for each part of the image forming apparatus so that the sound quality evaluation (discomfort probability P) based on the sound quality evaluation formula satisfies a predetermined condition is designed (S1: design process). The image forming apparatus is manufactured in accordance with the design content in which the discomfort probability P obtained from the sound emitted by the image forming apparatus satisfies a predetermined condition (S2: manufacturing process).

Through such a manufacturing process, an image forming apparatus that hardly generates unpleasant noise can be manufactured, and such an image forming apparatus can be provided to the user.
The present invention can also be applied as a noise countermeasure for image forming apparatuses once sold. That is, the sound generated by the image forming apparatus already sold or the like is measured as described above, and the discomfort probability P is derived from the measurement result using the sound quality evaluation formula. Whether the derived discomfort probability P satisfies a predetermined condition If it is satisfied, it is considered that there is almost no unpleasant noise, and it is determined that no modification is necessary.
On the other hand, when the derived discomfort probability P does not satisfy the predetermined condition, various modifications as described above are performed on each part of the image forming apparatus so that the discomfort probability P satisfies the predetermined condition. Accordingly, it is possible to provide an image forming apparatus that hardly generates unpleasant noise.

1 is an explanatory diagram illustrating an example of the overall configuration of an image forming apparatus (an apparatus having a plurality of modes) according to an embodiment of the present invention. It is explanatory drawing which shows the structural example of the optical unit in FIG. FIG. 2 is an explanatory diagram illustrating a cross-sectional view of a photoconductor unit and a development unit corresponding to a certain color in FIG. 1. FIG. 2 is an explanatory diagram illustrating a configuration example of a driving mechanism of the photosensitive unit in FIG. 1. FIG. 2 is an explanatory diagram illustrating a configuration example of a fixing unit in FIG. 1. FIG. 2 is an explanatory diagram illustrating a configuration example of a fixing unit in FIG. 1. FIG. 2 is an explanatory diagram illustrating a configuration example of a sheet feeding unit in FIG. 1. It is explanatory drawing which shows the structure of the 1st paper feed unit and the 2nd paper feed unit in FIG. It is explanatory drawing which shows the structural example of the image forming apparatus (desktop type) which concerns on embodiment of this invention. FIG. 10 is an explanatory diagram illustrating a configuration example of a process cartridge in FIG. 9. It is explanatory drawing which shows the structural example of the charging roller in FIG. 1 is a front view showing a schematic configuration of an image forming apparatus (medium speed digital copying machine) according to an embodiment of the present invention. It is explanatory drawing which shows the structural example of the image forming apparatus (console type) which concerns on embodiment of this invention. It is explanatory drawing which shows the neural network model of the standard type (only one hidden layer) used as a prediction model of sound quality evaluation. It is explanatory drawing of the measurement conditions in extraction | collection of the operation sound of an image forming apparatus. FIG. 10 is an explanatory diagram illustrating an analysis result of operation sound when an image forming apparatus having a plurality of modes operates at a color printing speed of 28 ppm. It is explanatory drawing which shows the analysis result of the operation sound when operating with the color printing speed of 14 ppm with respect to the image forming apparatus having a plurality of modes. It is explanatory drawing which shows the analysis result of the operation sound when the monochrome printing speed operates at 38 ppm for the image forming apparatus having a plurality of modes. It is explanatory drawing which shows the analysis result of the operation sound when a desktop type (desktop) image forming apparatus (20 ppm) operates. It is explanatory drawing which shows the analysis result of the operation sound when a medium-speed image forming apparatus (27 ppm) operate | moves. It is explanatory drawing which shows the analysis result of an operation sound when a large sized (console type) image forming apparatus (65 ppm) operate | moves. It is a graph which shows the relationship between the sound pressure level level of fixing oil application sound, and subjective evaluation value when it operates by color 28ppm. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound when it operate | moves with color 28ppm, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of a drum STM sound, and subjective evaluation value when it operate | moves by color 28ppm. It is a graph which shows the relationship between the sound pressure level level of a color development drive sound, and subjective evaluation value when it operate | moves by color 28ppm. It is a graph which shows the relationship between the sound pressure level level of a paper feeding STM sound, and a subjective evaluation value when it operates by color 28ppm. It is a graph which shows the relationship between the sound pressure level level of AC charging sound, and a subjective evaluation value when it operates by color 28ppm. It is a graph which shows the relationship between the sound pressure level level of a polygon mirror motor sound, and a subjective evaluation value when it operate | moves by color 28ppm. It is a graph which shows the relationship between the sound pressure level level of fixing oil application sound, and subjective evaluation value when it operate | moves by color 14ppm. It is a graph which shows the relationship between the sound pressure level level of AC electrification, a polygon, and a drum STM sound, and a subjective evaluation value when it operates by color 14ppm. It is a graph which shows the relationship between the sound pressure level level of a paper feeding STM sound, and a subjective evaluation value when it operates by color 14ppm. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound when it operate | moves with 14 ppm of colors, and a subjective evaluation value. It is a graph which shows the relationship between the sound pressure level level of development drive system sound, and a subjective evaluation value when it operates by monochrome 38ppm. It is a graph which shows the relationship between the sound pressure level level of fixing oil application sound, and subjective evaluation value when it operates by monochrome 38ppm. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound and a subjective evaluation value when it operate | moves by monochrome 38ppm. It is a graph which shows the relationship between the sound pressure level level of AC charging and drum STM sound, and subjective evaluation value when it operates by monochrome 38ppm. It is a graph which shows the relationship between a loudness level and subjective evaluation value at the time of operate | moving by monochrome 20ppm. It is a graph which shows the relationship between the sound pressure level level of a metal impact sound, and subjective evaluation value at the time of operate | moving by monochrome 20ppm. It is a graph which shows the relationship between the sound pressure level level of AC charging sound, and a subjective evaluation value when it operates by monochrome 20ppm. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound and a subjective evaluation value at the time of operating by monochrome 20ppm. It is a graph which shows the relationship between the sound pressure level level of a paper feeding sound, and a subjective evaluation value when it operates by monochrome 27ppm. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound and a subjective evaluation value when it operate | moves by monochrome 27ppm. It is a graph which shows the relationship between the sound pressure level level of a metal impact sound, and a subjective evaluation value when it operates by monochrome 27ppm. It is a graph which shows the relationship between the sound pressure level level of motor drive system sound, and a subjective evaluation value when it operates by monochrome 27ppm. It is a graph which shows the relationship between the sound pressure level level of a metal impact sound, and a subjective evaluation value at the time of operating by monochrome 65ppm. It is a graph which shows the relationship between the sound pressure level level of a paper sliding sound and a subjective evaluation value at the time of operate | moving by monochrome 65ppm. It is a graph which shows the relationship between the sound pressure level level of a paper impact sound, and subjective evaluation value at the time of operate | moving by monochrome 65ppm. It is a graph which shows the relationship between the sound pressure level level of a bank motor sound, and a subjective evaluation value when it operate | moves by monochrome 65ppm. It is a graph which shows the relationship between the sound pressure level level of a developing motor sound, and subjective evaluation value at the time of operate | moving by monochrome 65ppm. It is a graph which shows the relationship between the sound pressure level level of a main motor sound, and a subjective evaluation value at the time of operating by monochrome 65ppm. It is an example of a neural network that predicts the discomfort probability of printer sound when the number of units in the hidden unit layer is 1. It is a graph showing the relationship between the difference of the input acoustic physical quantity and the unpleasant probability of output about the result of the neural network analysis. It is a scatter diagram of an actual measurement value of an unpleasant probability when a pair of two sounds are compared and a predicted value derived using a model formula. It is a scatter diagram of a predicted value and a measured value using formula (d) for every eight experiments. 22 is a graph that approximates the relationship between ppm values and allowable values based on the results shown in Table 21. FIG. 22 is a graph that approximates the relationship between an image forming speed (mm / s) and an allowable value based on the results shown in Table 21. FIG. It is a diagram showing a drum drive mechanism including a color drum drive motor and a black drum drive motor before remodeling an image forming apparatus having a plurality of modes. It is a diagram showing a drum drive mechanism including a color drum drive motor and a black drum drive motor before remodeling an image forming apparatus having a plurality of modes. It is a figure which shows the drum drive mechanism after remodeling of the image forming apparatus which has multiple modes. It is a general view which shows the drum drive mechanism which interposed the vibration-proof rubber mount between the motor bracket and the drum drive motor. FIG. 5 is a partial view showing a drum drive mechanism in which a vibration isolating rubber mount is interposed between a motor bracket and a drum drive motor. It is a figure for demonstrating the motion of the rotor of the stepping motor driven by step angle (theta) ₀ . It is a figure which shows the sequence of 1-2 phase excitation which is one of the micro step drive of a stepping motor. It is a figure for demonstrating the countermeasure which attaches a Helmholtz resonator to the upper part of the housing holding a polygon mirror motor, and reduces the sound which a polygon mirror motor emits. It is a figure for demonstrating the countermeasure which reduces the charging sound at the time of a charging roller charging a photoconductor drum. It is a figure for demonstrating the countermeasure which reduces the charging sound at the time of a charging roller charging a photoconductor drum. When an image is formed by conveying paper stored in the first tray or the second tray (during normal printing) and when printing is performed without conveying the paper (during free run) It is a graph which shows the result of having measured the noise to emit and performing frequency analysis (1/3 octave band analysis). 68 is a graph showing a difference in sound pressure level in each frequency band obtained from noise during normal printing and free run shown in the analysis result of FIG. 67. FIG. 5 is a diagram for explaining measures for reducing sliding noise of a sheet conveyed by a sheet feeding unit, a relay roller, and a conveying roller. 6 is a diagram for explaining a configuration for reliably guiding a sheet to a roller 55. FIG. FIG. 6 is a diagram for explaining that a sheet from a conveyance path A is conveyed while sliding on a leading end portion of a guide member. It is explanatory drawing at the time of using the flexible sheet | seat of thickness t / 2 sheared to the predetermined shape as a guide member. It is explanatory drawing at the time of using the flexible sheet | seat of thickness t sheared to the predetermined shape as a guide member as it is. It is explanatory drawing which shows the detailed structure of the roller of the main body vertical conveyance unit in the image forming apparatus of FIG. 13, and a guide plate. It is explanatory drawing which shows the relationship between the recording paper at the time of noise non-measures, and a flexible sheet. It is an example of the flexible sheet | seat concerning embodiment of this invention. It is an example of the flexible sheet | seat concerning embodiment of this invention. It is explanatory drawing which shows the structure of the paper supply and drive system of the bank paper supply unit in FIG. It is a flowchart which shows the example of control of the intermediate clutch of a bank paper supply unit. It is a graph which shows the change of the metal impact sound before and after improvement of control of an intermediate clutch. It is a figure which shows the analysis result of the noise which the image forming apparatus which gave the countermeasure emits. It is a figure which shows the analysis result of the noise which the image forming apparatus before improvement and after improvement improves (front side). It is a figure which shows the analysis result of the noise which the image forming apparatus before improvement and after improvement improves (rear side). It is a figure which shows the analysis result of the noise which the image forming apparatus before and after improvement produces (left side). It is a figure which shows the analysis result of the noise which the image forming apparatus before improvement and after improvement improves (right side surface). It is process drawing which shows the development and manufacturing process of a new product.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical unit, 1 ... Paper, 2 ... Polygon mirror motor, 3 ... Photosensitive unit, 4 ... Developing unit, 5 ... Transfer unit, 6 ... P sensor, 7 ... Registration roller, 8 ... Manual feed tray, 8 ... Paper feed Tray, 9 ... first tray, 10 ... second tray, 11 ... housing, 110 ... feed section, 13 ... fixing belt, 16 ... waste toner bolt, 17 ... laser diode (LD) unit (Bk: black), 18 ... LD unit (C: Cyan), 19 ... LD unit (M: Magenta), 20 ... LD unit (Y: Yellow), 21, 22 ... Two-layer fθ lens, 23, 24, 25, 26 ... Long WTL lens 27 ... Polygon mirror, 27 ... 6-sided polygon mirror, 28 ... photosensitive drum, 29 ... transfer belt, 30 ... developing roller, 31 ... developing doctor, 32 ... conveying screw left, 3 ... Conveying screw right, 34 ... Toner density sensor, 35 ... Agent cartridge, 36 ... Charging roller, 37 ... Cleaning brush, 38 ... Counter blade, 39 ... Cleaning brush, 40 ... Waste toner collection coil, 41 ... Color drum drive motor 42 ... black drum drive motor, 43, 44 ... gear, 44 ... gear, 45 ... joint, 46 ... fixing unit, 47 ... oil application unit, 48 ... application felt, 49 ... application roller, 50 ... cleaning roller, 51 ... First paper feeding unit 52 ... Second paper feeding unit 53 ... Relay roller 54 ... Relay roller 55 ... Conveying roller 56 ... Feeding unit 57 ... First paper feeding clutch 58 ... Second paper feeding clutch 59 ... Motor bracket, 60 ... Anti-vibration rubber mount, 61,62 ... Gear, 63,64 ... Double gear / Pooh , 65: Motor bracket, 66, 67 ... Timing pulley, 68 ... Drum shaft, 69 ... Stud, 70 ... Timing belt, 700 ... Bearing, 71 ... Helmholtz resonator, 72 ... Cavity, 72a ... Cavity forming member, 73 ... Opening Hole, 74 ... damping member, 75 ... base, 76 ... blade, 77 ... guide member, 77a ... notch, 80, 81, 82 ... guide member, 83 ... stepping motor, 90 ... body tray, 201 ... covered Measuring device 202... Operation unit of image forming apparatus 203. Dummy head 204 204 Dummy head ear position (sound collecting position) 301. Photosensitive drum 302 302 Transfer roller 303 Process cartridge 304 Main body Paper feed tray, 305 ... Bank paper feed tray, 306 ... Manual feed tray, 307 ... Fixing unit, 308 ... Writing unit 309 ... discharge tray, 310 ... feed roller, 311 ... registration roller, 312 ... discharge roller, 321 ... charging roller, 321a ... core metal part, 321b ... charging part, 322 ... developing roller, 323 ... cleaning blade, 324 ... Toner, 325 ... Agitator, 326 ... Stirrer shaft, 327 ... Developing blade, 331 ... Electrode terminal, 332 ... Charging roller pressure spring, 333 ... Conductive bearing, 401 ... Main body, 402 ... Paper feed bank unit, 403 ... Reading system optical unit, 404 ... writing system optical unit, 405 ... light beam, 406 ... photoconductor, 407 ... charging roller, 408 ... developing roller, 409 ... transfer roller, 410 ... first-stage tray of main body, 411 ... of main body Second-stage tray, 412... First-stage tray of paper supply bank unit 402, 413. 402 second tray, 414... Paper feed roller, 415 .. conveyance auxiliary roller, 416... Registration roller pair, 417... Fixing device, 418 .. fixing roller pair, 419. ... Toner bottle 500. Upper part 501 Photoconductor drum 502 502 Charger charger 503 Development unit 504 Transfer / separation charger 505 Cleaning unit 506 Fixing unit 507 Registration roller 510 ADF 511: Document table 512: Contact glass 513: Exposure lamp 514: First mirror 515: Second mirror 516: Third mirror 517: Imaging lens 518: CCD 519: Mirror 520: Scanner 530: Writing unit, 540: Image forming engine, 570: Bank paper feeding unit 571 ... 1st tray, 572 ... 2nd tray, 573 ... 3rd tray, 574 ... 4th tray, 575 ... 1st paper feeder, 576 2nd ... paper feeder, 777 ... 3rd paper feeder, 578 ... Fourth sheet feeding device, 579 ... Bank vertical conveying unit, 580 ... Main body vertical conveying unit, 581 ... Discharge roller, 582 ... Switching claw, 585 ... Double-sided unit, 586 ... Double-sided conveying path, 590 ... Caster with lock function , 550 to 554 ... roller, 555 to 558 ... guide plate, 559 ... flexible sheet, 559a ... bent part, 561 ... bank motor, 562 to 565 ... intermediate clutch, 566 ... relay sensor, 567 ... grip roller, 568 ... Pressure spring, 569 ... driven roller.

Claims (28)

An image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target sheet picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus is subjected to image forming. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by the image forming apparatus, and output value of the image forming target sheet (A4 size lateral direction) per minute The following formula (a) using (ppm)
The probability P calculated by the following condition (b)
An image forming apparatus characterized by satisfying the above. An image forming apparatus for forming an image on an image forming target sheet, wherein the image is formed when image forming is performed on the image forming target sheet picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus. The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of the acoustic physical quantity obtained from the sound emitted from the forming apparatus, and the output numerical value of the image forming target sheet (A4 size lateral direction) per minute ( ppm) and the following formula (d)
The probability P calculated by the following condition (b)
An image forming apparatus characterized by satisfying the above. An image forming apparatus for forming an image on an image forming target sheet, wherein the image is formed when image forming is performed on the image forming target sheet picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus. The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value, and image forming speed (v: mm / s) of the image forming target sheet obtained from the sound emitted from the forming apparatus are used. The following formula (a)
The probability P calculated by the following condition (e)
An image forming apparatus characterized by satisfying the above. An image forming apparatus for forming an image on an image forming target sheet, wherein the image is formed when image forming is performed on the image forming target sheet picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus. The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of the acoustic physical quantity obtained from the sound emitted from the forming apparatus, and the output numerical value of the image forming target sheet (A4 size lateral direction) per minute ( ppm) and the following formula (d)
The probability P calculated by the following condition (e)
An image forming apparatus characterized by satisfying the above.   5. The image forming apparatus according to claim 1, wherein the image forming speed is different from the image forming speed and the image forming mode. An image forming apparatus, wherein the probability P satisfies the condition.   5. The image forming apparatus according to claim 1, wherein the sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, and at least the front surface of the apparatus (a surface having an operation unit). The image forming apparatus characterized in that the probability P calculated from the sound collection result of the sound in the direction satisfies the condition.   5. The image forming apparatus according to claim 1, wherein the sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, and sounds in four directions, front, rear, left, and right of the apparatus. An image forming apparatus, wherein an average value of the probabilities P calculated from each of the sound pickup results of the above satisfies the condition.   5. The image forming apparatus according to claim 1, wherein the sound collection position is a neighbor position defined in ISO (International Organization For Standardization) 7779, and is at least one of front, rear, left, and right of the apparatus. An image forming apparatus, wherein the probability P calculated from a sound collection result of a direction sound satisfies the condition.   5. The image forming apparatus according to claim 1, wherein the sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, and sounds in four directions, front, rear, left, and right of the apparatus. An image forming apparatus characterized in that all the probabilities P calculated from the respective sound collection results satisfy the condition.   10. The image forming apparatus according to claim 1, further comprising a reduction unit configured to reduce a sound generated by the apparatus when an image is formed on the image forming target sheet.   11. The image forming apparatus according to claim 10, further comprising: a stepping motor that drives a predetermined portion during image formation on the image forming target sheet; and a bracket member that holds the stepping motor, and the pure sound component reducing unit. Has an elastic body interposed between the stepping motor and the bracket member.   The image forming apparatus according to claim 10, further comprising a stepping motor that drives a predetermined part when forming an image on the image forming target sheet, wherein the pure sound component reducing unit drives the stepping motor to perform microstep driving. An image forming apparatus comprising a control unit.   The image forming apparatus according to claim 10, further comprising a motor that drives a predetermined portion when forming an image on the image forming target sheet, wherein the reduction unit includes a Helmholtz resonator disposed in the vicinity of the motor. An image forming apparatus.   The image forming apparatus according to claim 10, further comprising: a cylindrical image carrier having a hollow portion; and a charging unit that charges the surface of the image carrier. An image forming apparatus comprising a vibration damping member for suppressing vibration of the image carrier in a hollow portion.   The image forming apparatus according to claim 10, wherein the guide member is a guide member made of a flexible sheet that guides the image forming target sheet along a predetermined transport path, and is in contact with the transported image forming target sheet. The image forming apparatus further comprises a guide member that is a bent portion of the flexible sheet.   11. The image forming apparatus according to claim 10, wherein the toner used for image formation on the image forming target sheet is a toner containing wax.   The image forming apparatus according to claim 10, wherein the impact sound reduction unit uses an electromagnetic clutch provided in each of the paper feed conveyance paths having a plurality of paper feed stages as an electromagnetic clutch that is equal to or higher than the paper feed stage to be used. An image forming apparatus comprising: a sheet feeding / conveying control unit that controls the image forming apparatus. A method for manufacturing an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target sheet is picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus to be manufactured. A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from a sound emitted by the image forming apparatus when performing image formation, and the image forming target sheet (A4) per minute. The following formula (a) using the output value (ppm) in the horizontal direction)
The probability P calculated by the following condition (b)
A method for manufacturing an image forming apparatus, comprising: a design step for designing each part of the apparatus so as to satisfy the requirements; and a manufacturing step for manufacturing the image forming apparatus in accordance with a design content made by the design step. A method for manufacturing an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target sheet is picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus to be manufactured. A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from a sound emitted by the image forming apparatus when performing image formation, and the image forming target sheet (A4) per minute. The following formula (d) using the output value (ppm) in the horizontal direction)
The probability P calculated by the following condition (b)
A method for manufacturing an image forming apparatus, comprising: a design step for designing each part of the apparatus so as to satisfy the requirements; and a manufacturing step for manufacturing the image forming apparatus in accordance with a design content made by the design step. An image forming apparatus manufacturing method for forming an image on an image forming target sheet, wherein the image is picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus to be manufactured. The sound pressure level value, the loudness value, the sharpness value, the tonality value, the impulsiveness value of the acoustic physical quantity obtained from the sound emitted from the image forming apparatus when forming, and the image forming speed (v: mm / s) and the following formula (a)
The probability P calculated by the following condition (e)
A method for manufacturing an image forming apparatus, comprising: a design step for designing each part of the apparatus so as to satisfy the requirements; and a manufacturing step for manufacturing the image forming apparatus according to a design content made by the design step. An image forming apparatus manufacturing method for forming an image on an image forming target sheet, wherein the image is picked up at a sound pickup position 1 m away from an end surface of the image forming apparatus to be manufactured. The sound pressure level value, the loudness value, the sharpness value, the tonality value, the impulsiveness value of the acoustic physical quantity obtained from the sound emitted from the image forming apparatus when forming, and the image forming speed (v: mm / s) and the following formula (d)
The probability P calculated by the following condition (e)
A method for manufacturing an image forming apparatus, comprising: a design step for designing each part of the apparatus so as to satisfy the requirements; and a manufacturing step for manufacturing the image forming apparatus in accordance with a design content made by the design step. A method for remodeling an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target sheet is image-formed at a sound collecting position 1 m away from an end surface of the image forming apparatus to be remodeled. Sometimes a sound collecting step for picking up sound generated by the image forming apparatus, and an output numerical value (ppm) of the image forming target sheet (A4 size lateral direction) per minute obtained from a sound collecting result in the sound collecting step ) And the following formula (a)
The probability P calculated by the following condition (b)
And a remodeling step of remodeling the configuration of the apparatus so as to satisfy the requirements. A method of remodeling an image forming apparatus for forming an image on an image forming target sheet, wherein image forming is performed on the image forming target sheet at a sound collecting position 1 m away from an end face of the image forming apparatus to be remodeled. A sound collecting step for collecting sound emitted by the image forming apparatus, and a sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness of an acoustic physical quantity obtained from a sound collecting result in the sound collecting step. The following formula (d) using the value and the output numerical value (ppm) of the image forming target sheet (A4 size lateral direction) per minute
The probability P calculated by the equation is the following condition (b)
And a remodeling step of remodeling the configuration of the apparatus so as to satisfy the requirements. An image forming apparatus remodeling method for forming an image on an image forming target sheet, wherein the image forming target sheet is image-formed at a sound collecting position 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collecting step for picking up sound generated by the image forming apparatus, and a sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of an acoustic physical quantity obtained from the sound collecting result in the sound collecting step. And the following formula (a) using the image forming speed (v: mm / s) for the image forming target sheet
The probability P calculated by the equation is the following condition (e)
And a remodeling step of remodeling the configuration of the apparatus so as to satisfy the requirements. An image forming apparatus remodeling method for forming an image on an image forming target sheet, wherein the image forming target sheet is image-formed at a sound collecting position 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collecting step for collecting the sound generated by the image forming apparatus, and a sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from the sound collecting result in the sound collecting step. And the following formula (d) using the image forming speed (v: mm / s) for the image forming target sheet
The probability P calculated by the following condition (e)
And a remodeling step of remodeling the configuration of the apparatus so as to satisfy the requirements. An image forming apparatus for forming an image on an image formation target sheet is a method for evaluating a sound generated at the time of image formation, and a plurality of types of sounds generated by the image forming apparatus at the time of image formation are evaluated by a paired comparison method. A logistic regression analysis is performed using the probability of discomfort of two sounds by the evaluation as an objective variable and the difference between psychoacoustic parameter values as an explanatory variable, and the following formula (f) relating to the sound quality discomfort probability is obtained from the result.
And substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (f), and defining P = 0.5 at that time, the probability of sound discomfort A sound quality evaluation method characterized by deriving a sound quality evaluation formula for predicting sound quality and performing sound quality evaluation using the derived sound quality evaluation formula. An image forming apparatus manufacturing method for forming an image on an image forming target sheet, wherein a plurality of types of sounds generated by the image forming apparatus during image formation are evaluated by a paired comparison method. Logistic regression analysis is performed with the probability of discomfort as the objective variable and the difference in psychoacoustic parameter values as the explanatory variable.
And substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (f), and defining P = 0.5 at that time, the probability of sound discomfort A sound quality evaluation formula for predicting the sound quality is derived, and using the derived sound quality evaluation formula, each part of the apparatus is designed so that the sound quality evaluation based on the sound quality evaluation formula satisfies a predetermined condition, and an image forming apparatus is manufactured according to the design contents A method for manufacturing an image forming apparatus. A method of remodeling an image forming apparatus for forming an image on a sheet to be image formed, wherein the image forming apparatus evaluates a plurality of types of sounds generated at the time of image formation by a paired comparison method, and two sounds by the evaluation The logistic regression analysis is performed using the difference in psychoacoustic parameters as an explanatory variable, and the following equation (f) relating to the sound quality discomfort probability is performed.
And substituting the average value of the psychoacoustic parameter values used in the derivation of the above equation into the above equation (f), and defining P = 0.5 at that time, the probability of sound discomfort The sound quality evaluation formula for predicting the sound quality is derived, the sound quality evaluation of the image forming apparatus to be modified is performed using the derived sound quality evaluation formula, and the image forming apparatus to be modified is based on the sound quality evaluation result. A method for remodeling an image forming apparatus, wherein the structure is remodeled.