JP5381529B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus capable of maintaining image quality by suppressing vibration displacement of a latent image writing device against an external impact on an image forming apparatus and an internal impact caused by an operation of the image forming apparatus.

  Some electrostatic imaging type image forming apparatuses such as printers, copiers, and facsimiles are equipped with a latent image writing device. When an impact from the inside due to the impact or the operation of the image forming apparatus is received, a problem of image disturbance due to a position change of the latent image writing apparatus occurs.

  In order to prevent image disturbance due to the position fluctuation of the latent image writing device, it is necessary to ensure the positional accuracy of the latent image writing device.

The following is a conventional technique for ensuring the positional accuracy of the latent image writing device.

  The image forming apparatus described in Patent Document 1 moves the latent image writing apparatus from an operation position where the latent image writing apparatus operates to a retreat position where no operation is performed, as necessary. It is configured to improve the attachment / detachment maintenance performance of the latent image carrier and its peripheral devices exposed from the largely opened opening and to secure the positional accuracy at the operation position of the latent image writing device.

  The latent image writing device that moves between the operating position and the retracted position is configured to rotate around a shaft that is spanned between support members of the image carrier, and is one end of the latent image writing device. By supporting each end of the image carrier at three points with a shaft serving as a rotation shaft, the other end of the image carrier is supported at three points, thereby preventing rattling during the movement of the latent image writing device. It is configured to do.

  With this configuration, even if the latent image writing device is repeatedly moved, the positional accuracy reproducibility of the latent image writing device with respect to the image carrier at the operation position can be ensured, and image stability in normal operation can be obtained. It has become.

  In Patent Documents 2 and 3, the basic configuration of Patent Document 1 is developed. The latent image writing device is supported by a method in which the latent image writing device is abutted against the cover frame by an urging spring when the upper cover that is in the retracted position is open. In a state where the upper cover which is the operating position is closed, the upper cover is supported by a method of abutting against the positioning portion of the casing side plate by the same urging spring, and the support engagement with the cover frame is released.

  The contents of Patent Documents 4 and 5 prevent the external vibration transmitted to the latent image writing apparatus from being blocked or attenuated, so that the joint between the latent image writing apparatus and the support frame of the latent image writing apparatus is prevented. The configuration is through a vibration rubber.

  Further, in Patent Document 5, the anti-vibration rubber is laminated with a plurality of types of rubber to achieve vibration attenuation in a wide frequency range. According to this configuration, it is possible to reduce or attenuate the absolute vibration of the latent image writing device and its internal configuration.

  However, the following problems exist in the above-described prior art.

  Patent Document 1 has a configuration in which the latent image writing device cannot be in a completely fixed state by fastening or the like to the housing of the image forming device. Therefore, particularly when the latent image writing device is forming a latent image on the image carrier, an artificial impact on the surface of the image forming device or on the device itself (e.g. walking vibration, operation impact on the operation panel, etc.) Etc.), or when an operation impact of a clutch or solenoid for causing intermittent operation in the operation in the apparatus occurs, the impact vibration is easily propagated from the image forming apparatus to the latent image writing apparatus. Due to the impact vibration, the relative positional relationship between the latent image writing device and the image carrier is likely to be temporarily broken, and there is a problem that image disturbance occurs.

  In particular, at the support point where the image carrier and the latent image writing device are supported by the same support, the relative position fluctuation between the image carrier and the latent image writing device is small and less affected, but the image carrier In the present configuration in which one end of the latent image writing device is supported by a shaft that spans between support members that support the end portions of the body, the shaft itself vibrates as a beam due to the impact described above. The position of the support point of the latent image writing device changes due to the amplitude, and the relative posture of the latent image writing device with respect to the image carrier changes, and accordingly, the latent image creation position on the image carrier easily changes. There was a problem of becoming.

  In Patent Documents 2 and 3, one end of the latent image writing device is configured to be abutted and engaged with a cover frame by being urged by a spring from an upper cover, and when an impact similar to the above is applied. A similar problem occurs due to the vibration of the cover frame itself.

  Particularly in this case, the cover frame is fixed to the upper cover, that is, coupled and integrated. When an external impact is applied to the upper cover, the impact is directly applied to the latent image writing device through the cover frame. Therefore, there is a problem that the amount of posture fluctuation of the latent image writing device is larger than that of the configuration of Patent Document 1.

  As means for solving the above problem, it is also effective to increase the outer diameter of the shaft member and increase the section modulus (bending rigidity) of the support member in order to increase the rigidity of the member that supports the latent image writing device. However, on the other hand, an increase in the weight of the apparatus due to an increase in the weight of the support member, and a restriction on the position where the shaft is disposed due to an increase in the size of the parts, resulting in a problem of increasing the size of the apparatus.

  The problem with the inventions of Patent Documents 4 and 5 is only the problem of the relative attitude variation between the image carrier and the latent image writing device. When the image carrier is supported by the support frame in place of the basic configuration of the present invention, the support frame and the image carrier to which external vibration is applied perform absolute vibration, but the latent image writing device is prevented. The vibration is attenuated and the absolute vibration is reduced (that is, it means that the vibration isolating rubber expands and contracts).

  Therefore, as a result, the relative postures of the image carrier and the latent image writing device are fluctuated by vibration, and the problems described in Patent Documents 1 to 3 are not solved. . Rather, the change in relative posture depends on the relative response amplitude due to the artificial vibration to the device itself and the transient vibration such as the operation shock to cause intermittent operation in the operation of the device. The connection is preferably a rigid connection.

  Generally, a rubber material has a lower rigidity than a polymer resin material such as metal or plastic, and is not effective for this problem. Furthermore, the parts made of rubber have a large variation with respect to their own dimensional shape itself, and when they are interposed between the support frame and the latent image writing device, the positional accuracy of the original latent image writing device itself is high. The problem of degradation occurs.

  The present invention has been made in view of the above-described problems, and can suppress the vibration displacement of the support portion of the latent image writing device or the like with respect to an external impact or an impact during operation of the image forming apparatus, and can maintain image quality. An object is to provide an image forming apparatus.

  The image forming apparatus of the present invention includes an image carrier that carries a latent image on the surface, a first support member that supports one end of the image carrier, and a second support that supports the other end of the image carrier. A member, an inter-support member connecting member that bridges the first support member and the second support member, movable between an operation position for performing an exposure operation and a retracted position for not performing the exposure operation, and at least one end. A latent image writing device supported by the support member connecting member, the support member connecting member having flexibility, and a latent image writing device first support region and a latent image writing device. The latent image writing device first support region and the latent image writing device second support region are different in elasticity from each other.

  According to the present invention, without increasing the weight or size of the support of the latent image writing apparatus in the image forming apparatus, vibration displacement against external / internal shock to the latent image writing apparatus can be suppressed, and image formation is performed. The image quality of the apparatus can be maintained.

It is a schematic diagram around a rotating shaft according to an embodiment of the present invention. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a configuration diagram showing a process unit of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view illustrating an internal configuration of an image forming apparatus according to an embodiment of the present invention. 3 is a cross-sectional view of an optical writing unit left side positioning portion of the image forming apparatus according to the embodiment of the present invention. FIG. It is a vibration mode figure of the rotating shaft which concerns on embodiment of this invention. It is a schematic diagram around a rotating shaft according to an embodiment of the present invention. It is a perspective view around a rotating shaft according to an embodiment of the present invention. It is a schematic diagram around a rotating shaft according to an embodiment of the present invention. It is a figure which shows the displacement of the left side positioning protrusion which concerns on the conventional embodiment. It is sectional drawing which shows the displacement of the left side positioning protrusion which concerns on the conventional embodiment.

  Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a schematic sectional view showing a basic configuration example of an electrophotographic printer (hereinafter simply referred to as a printer) as an image forming apparatus according to an embodiment of the present invention. This example shows a full-color image forming apparatus using a general electrostatic imaging method, and does not limit the effect of the present invention.

  The printer includes process units 1Y, 1M, 1C, and 1K for forming toner images of yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K). These use Y, M, C, and K toners of different colors as the image forming material, but the other configurations are the same and are replaced when the lifetime is reached.

  Taking a process unit 1K for forming a K toner image as an example, as shown in FIG. 3, a drum-shaped photosensitive member 2K as a latent image carrier, a drum cleaning device 3K, a charge eliminating device (not shown), and a charging device 4K. And a developing device 5K. The process unit 1K, which is an image forming unit, is detachable from the printer body, and can be replaced as a consumable part at a time.

  The charging device 4K uniformly charges the surface of the photoreceptor 2K that is rotated clockwise in the drawing by a driving unit (not shown). The uniformly charged surface of the photosensitive member 2K is exposed and scanned by the laser beam L to carry an electrostatic latent image for K. The electrostatic latent image for K is developed into a K toner image by a developing device 5K using K toner (not shown). Then, it is transferred onto an intermediate transfer belt 16 described later.

  The drum cleaning device 3K removes transfer residual toner remaining on the surface of the photoreceptor 2K after being transferred onto the intermediate transfer belt 16. The static eliminator neutralizes residual charges on the photoreceptor 2K after cleaning. By this charge removal, the surface of the photoreceptor 2K is initialized and prepared for the next image formation. In the other color process units (1Y, M, C), Y, M, and C toner images are formed on the photoreceptors (2Y, M, C) in the same manner, and are formed on an intermediate transfer belt 16, which will be described later. Superimposed transfer.

  The developing device 5K includes a hopper unit 6K that stores K toner (not shown) and a developing unit 7K. In the hopper 6K, an agitator 8K, a stirring paddle 9K, a toner supply roller 10K, and the like that are rotationally driven by a driving unit (not shown) are disposed. The K toner in the hopper 6K moves toward the toner supply roller 10K by its own weight while being stirred by the rotational drive of the agitator 8K and the stirring paddle 9K. The toner supply roller 10K has a metal cored bar and a roller part made of foaming resin or the like coated on the surface thereof, and rotates while adhering the toner in the hopper part 6K to the surface of the roller part. To do.

  In the developing unit 7K of the developing device 5K, a developing roller 11K that rotates while contacting the photoconductor 2K and the toner supply roller 10K, and a thinning blade 12K that contacts the tip of the developing roller 11K are disposed. . The K toner adhered to the toner supply roller 10K in the hopper 6K is supplied to the surface of the development roller 11K at the contact portion between the development roller 11K and the toner supply roller 10K.

  When the supplied K toner passes through the contact position between the roller and the thinning blade 12K as the developing roller 11K rotates, the layer thickness on the roller surface is regulated. Then, the K toner after the layer thickness regulation adheres to the electrostatic latent image on the surface of the photosensitive member 2K in the developing region which is a contact portion between the developing roller 11K and the photosensitive member 2K. By this adhesion, the electrostatic latent image for K is developed into a K toner image.

  The process unit for K has been described with reference to FIG. 3, but the process units 1Y, M, and C for Y, M, and C also perform Y, M, and C on the surfaces of the photoreceptors 2Y, M, and C by a similar process. A C toner image is formed.

  2, the optical writing unit 70 is disposed above the process units 1Y, M, C, and K in the vertical direction. The optical writing unit 70, which is a latent image writing device, optically scans the photoreceptors 2Y, M, C, and K in the process units 1Y, M, C, and K with laser light L emitted from a laser diode based on image information. To do. By this optical scanning, electrostatic latent images for Y, M, C, and K are formed on the photoreceptors 2Y, M, C, and K. The optical writing unit 70 irradiates the photosensitive member through a plurality of optical lenses and mirrors while deflecting the laser light L emitted from the light source in the main scanning direction by the polygon mirror 71b that is rotationally driven by the polygon motor 71a. To do.

  Below the process units 1Y, 1M, 1C, and 1K, there is disposed a transfer unit 15 that moves the endless intermediate transfer belt 16 endlessly in the counterclockwise direction while stretching. In addition to the intermediate transfer belt 16, the transfer unit 15 serving as transfer means includes a driving roller 18, a driven roller 17, four primary transfer rollers 19Y, 19M, 19C, 19K, a secondary transfer roller 20, a belt cleaning device 21, and a cleaning device. A backup roller 22 and a residual toner collecting device 23 are provided.

  The intermediate transfer belt 16 is stretched by a driving roller 18, a driven roller 17, a cleaning backup roller 22, and four primary transfer rollers 19Y, 19M, 19C, and 19K disposed inside the loop. Then, it is moved endlessly in the same direction by the rotational force of the driving roller 18 that is driven to rotate counterclockwise in the figure by a driving means (not shown).

  The four primary transfer rollers 19Y, 19M, 19C, and 19K sandwich the intermediate transfer belt 16 that is moved endlessly in this manner between the photoreceptors 2Y, 2M, 2C, and 2K. By this sandwiching, primary transfer nips for Y, M, C, and K where the surface of the intermediate transfer belt 16 and the photoreceptors 2Y, 2M, 2C, and 2K abut are formed.

  A primary transfer bias is applied to each of the primary transfer rollers 19Y, 19M, 19C, and 19K by a transfer bias power source (not shown). A transfer electric field is formed between the next transfer rollers 19, Y, M, C, and K. In place of the primary transfer rollers 19Y, 19M, 19C, and 19K, a transfer charger, a transfer brush, or the like may be employed.

  When the K toner formed on the surface of the photoconductor 2K of the K process unit 1K enters the K primary transfer nip as the photoconductor 2K rotates, the photoconductor is exposed to light due to the transfer electric field and the nip pressure. Primary transfer is performed on the transfer belt 16 from the body 2K. The intermediate transfer belt 16 on which the K toner image has been primarily transferred in this way passes over the primary transfer nip for C, M, and Y along with the endless movement thereof, and then on the photoreceptors 2C, M, and Y. The C, M, and Y toner images are sequentially superimposed and transferred onto the K toner image. A four-color toner image is formed on the intermediate transfer belt 16 by the primary transfer of superposition.

  While the secondary transfer roller 20 of the transfer unit 15 is disposed outside the loop of the intermediate transfer belt 16, the intermediate transfer belt 16 is sandwiched between the drive roller 18 inside the loop. By this sandwiching, a secondary transfer nip where the surface of the intermediate transfer belt 16 and the secondary transfer roller 20 abut is formed. A secondary transfer bias is applied to the secondary transfer roller 20 by a transfer bias power source (not shown). By this application, a secondary transfer electric field is formed between the secondary transfer roller 20 and the driving roller 18.

  Below the transfer unit 15, a paper feed cassette 30 that stores a plurality of recording papers P in a bundle of sheets is slidably attached to the printer housing. In the paper feed cassette 30, a paper feed roller 30a is brought into contact with the uppermost recording paper P of the paper bundle. By rotating the paper feeding roller 30a counterclockwise at a predetermined timing, the recording paper P To the paper feed path 31.

  A registration roller pair 32 is disposed near the end of the paper feed path 31. The registration roller pair 32 stops the rotation of the rollers as soon as the recording paper P delivered from the paper feed cassette 30 is sandwiched between the rollers. Then, the rotational movement is restarted at a timing at which the sandwiched recording paper P can be synchronized with the four-color toner image on the intermediate transfer belt 16 in the above-described secondary transfer nip, and the recording paper P is sent out toward the secondary transfer nip. .

  The four-color toner image on the intermediate transfer belt 16 brought into close contact with the recording paper P at the secondary transfer nip is secondarily transferred onto the recording paper P under the influence of the secondary transfer electric field and the nip pressure. A full color toner image is formed on P. The recording paper P having the full-color toner image formed on the surface in this manner is separated from the secondary transfer roller 20 and the intermediate transfer belt 16 by the curvature when passing through the secondary transfer nip. Then, the toner is fed into a fixing device 34 described later via a post-transfer conveyance path 33.

  The transfer residual toner that has not been transferred to the recording paper P adheres to the intermediate transfer belt 16 after passing through the secondary transfer nip. This is cleaned from the belt surface by the belt cleaning device 21 in contact with the surface of the intermediate transfer belt 16. The cleaning backup roller 22 disposed inside the loop of the intermediate transfer belt 16 backs up the cleaning of the belt by the belt cleaning device 21 from the inside of the loop. The residual toner cleaned from the surface of the intermediate transfer belt 16 by the belt cleaning device 21 is recovered to the residual toner recovery device 23.

  The fixing device 34 forms a fixing nip by a fixing roller 34a containing a heat source such as a halogen lamp (not shown) and a pressure roller 34b that rotates while contacting the fixing roller 34a with a predetermined pressure. The recording paper P fed into the fixing device 34 is sandwiched between the fixing nips such that the unfixed toner image carrying surface is brought into close contact with the fixing roller 34a. Then, the toner in the toner image is softened by the influence of heating and pressurization, and the full color image is fixed.

  The recording paper P discharged from the fixing device 34 passes through the post-fixing conveyance path 35 and is then sandwiched between the rollers of the paper discharge roller pair 37, and the upper surface of the upper cover 50 is rotated by the rotation of the paper discharge roller pair 37. Stacked in the stack part.

  The upper cover 50 and the optical writing unit 70 are supported so as to be rotatable about the rotation shaft 100 as indicated by the arrows in the drawing, and are rotated counterclockwise in the drawing to be attached to the casing. It will be in an open state. Then, the upper opening of the housing is greatly exposed to the outside. Thereby, each of the four process units 1Y, 1M, 1C, and 1K can be easily attached and detached from the upper opening in the direction of the arrow in the figure.

  Hereinafter, for the sake of simplicity, the front side in the direction orthogonal to the illustrated surface in FIG. 2 is defined as the front surface of the printer, and the back side is defined as the rear surface. In the figure, the right side is the right side and the left side is the left side. However, as a matter of course, the front / rear / right / left direction may be set in any way and does not limit the effect of the present invention.

  FIG. 4 is a perspective view showing the internal configuration of the printer. A main body frame for supporting various devices is erected in the printer casing. The main body frame includes a front side plate 80, a rear side plate 90, a rotary shaft 100, a left side plate, a beam plate (not shown), and the like. It is configured. The front side plate 80 is a side plate disposed on the front side in the printer casing, and the rear side plate 90 is a side plate disposed on the rear side in the printer casing. The front side plate 80 and the rear side plate 90 are connected by a rotating shaft 100, a left side plate and a beam plate (not shown) so as to stand upright while facing each other with a predetermined distance.

  A transfer unit, four process units, and an optical writing unit 70 (not shown) are disposed between the front plate 80 and the rear plate 90 facing each other at a predetermined distance. In the drawing, only the rightmost K process unit 1K is visible among the four process units, and the other color process units are located immediately below the optical writing unit 70. Then it is not visible. Although not shown in the drawing, one end of each of the photoreceptors 2Y, M, C, and K in the four process units is rotatably supported by a front plate 80 and the other end by a rear plate 90.

  A front cover frame 72 is disposed between the optical writing unit 70 and the front plate 80, and a rear cover frame 73 is disposed between the optical writing unit 70 and the rear plate 90. It is supported by. The front cover frame 72 and the rear cover frame 73 may be fastened or integrally formed with an upper cover (not shown) (not shown).

  On the front side surface and the rear side surface of the optical writing unit 70, a front positioning shaft 70a and a rear positioning shaft 70b are projected. The front cover frame 72 has a front opening 72a, and the rear cover frame 73 has a rear opening 73a. The front positioning shaft 70a and the rear positioning shaft 70b each have a predetermined backlash, and the front opening 72a and the rear opening 73a.

  A front positioning groove 81 is formed in the front plate 80, and a rear positioning groove 91 is formed in the rear plate 90. The front positioning shaft 70a and the rear positioning shaft 70b penetrating the front opening 72a and the rear opening 73a are arranged in the front positioning. It is supported at the position of the groove 81 and the rear positioning groove 91. Further, between the front cover frame 72 and the front positioning shaft 70a and between the rear cover frame 73 and the rear positioning shaft 70b, a front pressing spring 74 and a rear side that press the optical writing unit in a predetermined direction, respectively. A pressing spring 75 is provided, and the amount of play between the front positioning groove 81, the rear positioning groove 91, the front positioning shaft 70a, and the rear positioning shaft 70b in the pressing direction by the front pressing spring 74 and the rear pressing spring 75 is reduced. Are set to be smaller than the backlash of the front opening 72a, the rear opening 73a, the front positioning shaft 70a, and the rear positioning shaft 70b.

  Thus, in the state shown in the figure, which is the operating position of the optical writing unit 70, the front positioning spring 70 and the rear pressing spring 75 cause the front positioning shaft 70a and the rear positioning shaft 70b to move to the front positioning groove 81 and the rear positioning groove 91, respectively. In the state where the optical writing unit 70, which is pressed and positioned at a predetermined position of the optical writing unit 70, rotates around the rotary shaft 100 and is opened with respect to the housing, which is the retracted position of the optical writing unit 70, the front pressing spring 74 and the rear The front positioning shaft 70a and the rear positioning shaft 70b are pressed and urged against the front opening 72a and the rear opening 73a by the side pressing spring 75, and are supported in a state where rattling of the optical writing unit 70 is suppressed.

  On the other hand, a left positioning protrusion 71 is disposed on the left side surface of the optical writing unit 70 and is engaged with the rotary shaft 100. Thus, the optical writing unit 70 is positioned by three-point support of the front positioning shaft 70a, the rear positioning shaft 70b, and the left positioning protrusion 71. FIG. 5 shows a cross-sectional view of the left side positioning portion of the optical writing unit 70. The left positioning protrusion 71 at the operating position is supported on the rotating shaft 100 by receiving a force downward in the vertical direction with respect to the rotating shaft 100 due to the weight of the optical writing unit 70.

  In order to prevent rattling when the optical writing unit 70 is opened, the holding spring 76 is installed in the optical writing unit 70, and the rotating shaft 100 is sandwiched between the left positioning protrusion 71 and the holding spring 76. However, since the purpose is to prevent rattling when the optical writing unit 70 is opened, the rotating shaft 100 of the holding spring 76 is pressed against the rotating shaft 100 with a weak force, and rotates with the holding spring 76 in the operating position. The shaft 100 may not be in contact.

  In such a configuration, when the optical writing unit 70 is in the operating position and an electrostatic latent image is formed on the photosensitive members 2Y, 2M, 2C, and 2K described in FIG. Or artificial external impact on the printer itself (for example, walking vibration, operation impact on the operation panel, etc.), or intermittent operation such as a clutch or solenoid that drives the paper feed roller 30a, the registration roller pair 32, etc. at a predetermined timing. When an impact occurs, the entire printer casing is vibrated by the impact, generating a transient vibration.

  At this time, as described above with reference to FIG. 4, the optical writing unit 70 is not completely fixed with respect to the printer housing, and the optical writing unit 70 itself has its own weight, the front pressing spring 74, the rear pressing spring. 75 and the holding spring 76 are biased and supported by the spring, so that the positional relationship with respect to the front plate 80 and the rear plate 90 which are the housings holding the photoreceptors 2Y, 2M, 2C, and 2K is temporarily lost. It becomes easy.

  In particular, at the support positions by the front positioning shaft 70a and the rear positioning shaft 70b that directly support the photoreceptors 2Y, M, C, and K and the optical writing unit 70 with the front plate 80 and the rear plate 90 that are the same support. The relative position variation between the photoconductors 2Y, M, C, and K and the optical writing unit 70 is small and has little influence, but the left positioning protrusion 71 that supports the optical writing unit 70 by the rotary shaft 100 At the support position, the rotation shaft 100 itself vibrates as a beam, so that a relative position variation between the photoconductors 2Y, 2M, 2C, and 2K and the optical writing unit 70 occurs.

  Specifically, as shown in the schematic diagram around the rotary shaft 100 when the printer is viewed from the left side in FIG. 10, the rotary shaft 100 vibrates as a beam having both ends held by the front side plate 80 and the rear side plate 90. . The vibration mode in which the displacement amount by the rotation shaft 100 at the position of the left positioning protrusion 71 is the largest is the primary vibration mode of the rotation shaft 100 as indicated by a broken line in the drawing. Further, this vibration is caused by the weight of the rotating shaft 100 itself or the support force of the left positioning protrusion 71 that bears a part of the weight of the optical writing unit 70 (not shown) according to the acceleration generated by an external impact or intermittent operation. It is a transient response vibration that is vibrated by the inertial force of.

  As a result, as shown in the schematic diagram of FIG. 11, when the support position of the left positioning protrusion 71 is displaced in the vertical direction, which is the arrow direction in the figure, due to the transient response vibration amplitude of the rotating shaft 100, the front positioning shaft 70a and the unillustrated Although the relative positional relationship of the rear positioning shaft 70b with respect to the photosensitive members 2Y, M, C, and K does not change, the relative positional relationship between the left positioning protrusion 71 and the photosensitive members 2Y, M, C, and K changes. As indicated by the middle broken line, the position of the optical writing unit 70 is inclined with respect to the positions of the photoconductors 2Y, 2M, 2C, 2K, and the surface positions of the photoconductors 2Y, 2M, 2C, 2K of the laser light L Fluctuates in the sub-scanning direction, resulting in image disturbance.

  As described above, the excitation force of the rotating shaft 100 is an inertial force including the own weight of the rotating shaft 100 according to the acceleration generated by an external impact or intermittent operation. Therefore, in order to suppress the amplitude of the rotating shaft 100, it is only necessary to increase the rigidity of the rotating shaft or reduce the mass. As described above, the rotating shaft 100 has a cylindrical rod shape, and if the same material is used, the rigidity of the rotating shaft 100 is proportional to the fourth power of the outer diameter D in FIG. Since the mass is proportional to the square of the outer diameter D, as a short-circuit method, the amplitude can be reduced by increasing the outer diameter D. On the other hand, increasing the weight leads to an increase in the weight of the printer and an increase in size.

  FIG. 1 is a schematic diagram of the periphery of a rotary shaft 100 as viewed from the left side of the printer, which is a characteristic configuration of the printer according to the present invention. The connection form of each member in the rotating shaft 100, the front side plate 80, the rear side plate 90, and the left positioning protrusion 71 that receives a part of its own weight of the optical writing unit 70 is the same as that shown in FIG. However, the rotating shaft 100 has flexibility and forms a stepped shape at the position of the stepped portion 100a.

  The left positioning protrusion 71 is in the left first support region 100b, which is a region from the rotary shaft first connecting portion 90a to the stepped portion 100a, which is a connecting portion with the rear plate 90, and the stepped portion 100a. The rotating shaft 100 is supported by the left positioning portion 101 which is substantially the same position in the axial direction. Accordingly, the rotation shaft 100 is between the left first support region 100b and the left second support region 100c which is a region up to the rotation shaft second connection portion 80a which is a connection portion between the front plate 80 and the rotation shaft 100. Form shapes that have different moduli of elasticity.

Note that the outer diameter Da of the rotating shaft 100 in the left first support region 100b is larger than the outer diameter Db of the rotating shaft 100 in the left second support region 100c (Da> Db). Since the rotating shaft 100 has a solid cylindrical shape, the bending rigidity in each region is proportional to the fourth power of the outer diameter due to the second moment of the cross section, and the mass per unit axial length of the rotating shaft 100 depends on the volume. It is proportional to the square of the outer diameter. Therefore, the bending stiffness of the rotating shaft 100 in the left first support region 100b is K1, the mass per unit length is M1, the bending stiffness of the rotating shaft 100 in the left second support region 100c is K2, and the mass per unit length is M2 means that K1 / M1> K2 / M2 is set (Da ² > Db ² ).

  Further, the length Lb of the left first support region 100b on the rotating shaft 100 is configured to be shorter than the length Lc of the left second support region 100c (Lb <Lc).

  As described above, the excitation force to the rotating shaft 100 generated by an external impact or intermittent operation is an inertial force including the own weight of the rotating shaft 100 according to the impact acceleration. According to this configuration, the primary vibration mode of the rotating shaft 100 is a mode in which the amplitude is biased toward the left second support region 100c as indicated by a broken line in the drawing. That is, the left second support region 100c can take most of the amplitude of the rotating shaft 100 that causes the position variation of the left positioning protrusion 71.

  This will be described in more detail with reference to FIG. 6 showing the vibration mode difference depending on the shape of the rotating shaft 100. FIG. 6 is a vibration mode diagram of the rotating shaft 100 when the shape of the rotating shaft 100 is changed. The vertical axis indicates the axial position of the rotating shaft 100, and the horizontal axis indicates the amount of deflection (amplitude) of the rotating shaft 100. It is. In the figure, the line indicated by the curve P is the vibration mode of the rotating shaft 100 in the present embodiment described in FIG.

  A line indicated by a curve Q is a vibration mode of the rotating shaft 100 in the form of FIG. 11 formed in a uniform cross section by the rotating shaft 100 outer diameter Da of the left first support region 100b in FIG. 1 (D = Da). A line indicated by a curve R is a vibration mode of the rotary shaft 100 in the form of FIG. 11 formed in a uniform cross section by the rotary shaft 100 outer diameter Db of the left second support region 100c in FIG. 1 (D = Db). The line shown by the curve S is the vibration mode of the rotating shaft 100 in the form of FIG. 11 having an outer diameter D having the same mass as the rotating shaft 100 in FIG. 1 and having a cross section (Da> D> Db) . Note that the positions of the left positioning portion 101 of the optical writing unit 70 are indicated by 101P, 101Q, 101R, and 101S, respectively, in FIG.

  The amplitudes of the rotating shaft 100 generated by external impact or intermittent operation are compared. First, when the curves Q and R are compared, the form indicated by the curve Q is different from the form indicated by the curve R in that the outer diameter D of the rotating shaft 100 is larger. When the outer diameter D increases, the inertial force of the rotating shaft 100, which is an excitation force, increases due to the increase in the own weight. However, the effect of increasing the bending rigidity is greater than this influence. Is smaller (101Q <101R).

  Next, each is compared with the curve P which is this embodiment. As the vibration mode, the curve P is substantially the same as the curve Q at the axial position close to the rotary shaft first connecting portion 90a, and the curve R is substantially the same at the axial position close to the rotary shaft second connecting portion 80a. It becomes. Therefore, the displacement of the rotating shaft 100 becomes a vibration mode biased toward the left second support region 100c, and the displacement amount of the left positioning portion 101 can be minimized (101P> 101Q> 101R). Furthermore, the axial position of 101Q in the curve Q is the same as the 101P position, that is, even when the left positioning portion 101 is simply brought close to the rotary shaft first connecting portion 90a and the 101P position of the curve P is compared with 101P. The amount of displacement at the position is substantially the same.

  That is, even if the outer diameter of the rotating shaft 100 is uniformly increased, the curve P means that the same effect is obtained without causing an increase in weight or an increase in size. Further, as can be seen by comparing the curve P and the curve S, when the mass of the rotating shaft 100 is the same, the displacement amount at the 101P position is approximately 1/4 (difference SP1) of the displacement amount at the 101S position, and the curve S. In this case, the displacement amount at the 101P position of the curve P is approximately ½ of the displacement amount of the curve S (difference SP2) even if the position of the left positioning portion 101 in the axial direction of the rotation axis 101 is the same as the 101P position. Could get.

  As described above, the function of the present invention is that the length of the left first support region 100b and the rigidity and mass of the rotating shaft 100 in the left first support region 100b are different from those of the left second support region 100c. The posture of the optical writing unit 70 is reduced by reducing the displacement due to the vibration of the left first support region 100b by providing the continuity and allowing the left second support region 100c to receive the displacement due to the vibration of the rotating shaft 100. Can be stabilized.

  Next, examples according to the present invention that can obtain further effects will be described. FIG. 7 is a schematic diagram of the vicinity of the rotary shaft 100 when the printer is viewed from the left side in the present embodiment. Although the basic configuration is the same as that of FIG. 1, the difference from the above-described embodiment is that vibration damping means is added to the left second support region 100c. As described above, in order to reduce the displacement due to the vibration of the left first support region 100b, the displacement of the rotation shaft 100 due to the vibration is received by the left second support region 100c having low rigidity. Therefore, in order to further attenuate this vibration, it is effective to provide a damping means for imparting a vibration damping effect to the left second supporting region 100c having a large displacement amount by the displacement itself.

  As shown in FIG. 7, a cylindrical anti-vibration rubber 102 is coated on the outer periphery of the rotation shaft 100 of the left second support region 100c, which is a region where the outer diameter of the rotation shaft 100 is small, as vibration damping means. The anti-vibration rubber 102 may be formed by integrally vulcanizing and molding urethane rubber, EPDM rubber or the like to the rotating shaft 100, or may be formed by press-fitting or bonding a tube-shaped material to the rotating shaft 100. Of course, the same effect can be obtained by using a viscoelastic body such as natural rubber, resin rubber, or elastomer.

  As described above, the rotating shaft 100 vibrates in a mode biased toward the left second support region 100c. That is, the anti-vibration rubber 102 provided in the left second support region 100c having a large deformation amount is also subjected to a large bending deformation in a similar manner, and the anti-vibration rubber 102 is installed in the left first support region 100b having a small deformation amount. The vibration of the rotating shaft 100 can be damped with a large damping effect. In addition, since the left positioning protrusion 71 can be directly supported on the rotating shaft 100 without the vibration isolating rubber 102 interposed in the left positioning portion 101, deformation such as expansion and contraction of the vibration isolating rubber 102 generated when subjected to vibration. However, it does not affect the left positioning part 101. Furthermore, the object can be achieved without causing a variation in the dimensions of the vibration isolating rubber 102 itself or a change in the position of the left positioning protrusion 71 due to a change in dimension at the time of joining.

  FIG. 8 is a perspective view of the periphery of the rotary shaft 100 showing a development example of the present invention. The rotary shaft 100 has a stepped shape in the middle of the axial direction as in the embodiments described so far. The thicker end of the outer diameter is directed to the rear side plate 90 and the thinner end is directed to the front side plate 80. Each is connected. A fixing auxiliary metal fitting 103 is provided at a connecting portion between the rotary shaft 100 and the rear plate 90, and the rotary shaft 100 is firmly fixed to the rear plate 90 by a fastening screw 104.

  On the other hand, the connecting portion between the rotating shaft 100 and the front side plate 80 only restricts the axial displacement of the rotating shaft 100 by the E ring 105, and the connecting strength of the rotating shaft 100 and the rear side plate 90 is The structure is relatively higher than the connection strength with the front side plate 80. Further, a vibration-proof rubber 102 is coated on the outer periphery of the rotating shaft 100 having a thin outer diameter, and the left positioning protrusion 71 of the optical writing unit 70 (not shown) is supported by a region having a large outer diameter of the rotating shaft 100. Has been.

  FIG. 9 shows a schematic diagram of the periphery of the rotary shaft 100 when the printer is viewed from the left side in this development example. As shown in FIG. 9, as the end support form of the rotating shaft 100, the rotating shaft first connecting portion 90 a that is a connecting portion with the rear plate 90 is fixed, and the rotating shaft first connecting portion that is the connecting portion with the front plate 80 is used. The two connecting portions 80a can be simplified as simple support. The rotating shaft 100 has a larger amplitude when the same excitation force is applied to the simple support than to the fixed end support form. Therefore, as shown by the broken line in FIG. As a result, the left side second support region 100c vibrates in a shape with a biased amplitude. Since the anti-vibration rubber 102 is coated on the left second support region 100c, the anti-vibration rubber 102 absorbs larger vibration energy, and the vibration of the left positioning portion 101 can be suppressed.

  As described above, the above-described embodiment has the following features.

  As a first feature, the inter-support member connecting member is flexible and includes a latent image writing device first support region and a latent image writing device second support region, and the latent image document. It is preferable that the elastic moduli of the first support area of the inserting device and the second support area of the latent image writing device are different from each other.

  The purpose of the first feature is that when a latent image writing device that is not identical to the casing on which the latent image carrier is supported receives a vibration force generated by an impact, the latent image The deformation mode of the support is made non-uniform so that the vibration of the support is received in a region that does not directly contribute to the support of the embedding device, and the vibration amplitude of the region that directly contributes to the support of the latent image writing device is suppressed. It is.

  The effect of the first feature is that vibration displacement of the latent image writing device support portion can be suppressed without increasing the weight and size of the support and latent image writing device.

  The action of the first feature is that each region in the support body has a relative difference in rigidity or mass, and the deformation of the support body due to the excitation force is not targeted, and the vibration is transferred to the latent image writing device. In other words, the amplitude of the support portion of the latent image writing apparatus is reduced by concentrating on a region that does not directly contribute to support of the latent image writing device.

  As a second feature, the inter-support member connecting member has a latent image writing from a connecting portion with the first supporting member to a first latent image writing device support portion on which the latent image writing device is supported. A latent image writing device second support region from a connecting portion between the device first support region and the second support member to the front of the first latent image writing device support portion where the latent image writing device is supported Are connected to each other, and the bending rigidity in the first support region of the latent image writing device is K1 and the mass per unit length is M1 with respect to the direction in which the first support member and the second support member are bridged. And K1 / M1> K2 / M2, where K2 is the bending stiffness in the second support area of the latent image writing device and M2 is the mass per unit length, and the first latent image writing device support section. Is in front of the connecting portion of the first support area of the latent image writing device and the second support area of the latent image writing device. It is preferable that the latent image writing device the first support region side near.

  The purpose of the second feature is due to the weight of the support itself, which is an excitation force generated by an impact, in the support of the latent image writing device that is not identical to the casing on which the latent image carrier is supported. Reduce the vibration amplitude of the region that directly contributes to the support of the latent image writing device by making the inertial force as small as possible and to allow the support to vibrate in the region that does not directly contribute to the support of the latent image writing device. It is.

  The function of the second feature is that, for each region in the support body of the latent image writing device, the region that does not directly contribute to the support of the latent image writing device has a lower mass relative to the support portion region and is supported. The inertia force due to the weight of the entire part is reduced, or the rigidity is relatively lowered, and the displacement generated by the inertia force is concentrated. That is, by dividing the bending rigidity in the support portion of the latent image writing device by the mass per unit length so as to be relatively large with respect to the region that does not directly contribute to the support, That is, the vibration of the support member caused by the impact excitation is concentrated in a region that does not directly contribute to the support of the latent image writing device.

  As a third feature, the inter-support member connecting member is an inter-support member shaft member integrally formed as a support shaft when the latent image writing device rotates and moves between the operating position and the retracted position. Preferably, the outer diameter of the first support area of the latent image writing device is larger than the outer diameter of the shaft member between the support portions in the second support area of the latent image writing device.

  The purpose of the third feature is to reduce the inertia force due to the weight of the support itself by a simple method as much as possible, and to allow the support to vibrate in an area that does not directly contribute to the support of the latent image writing device. It is to suppress the vibration amplitude of the region that directly contributes to the support of the image writing apparatus.

  The effect of the third feature is to achieve the above object with a simple configuration.

  The operation of the third feature is that the support area of the latent image writing device is about a support shaft for moving the latent image writing device shared as a support member of the latent image writing device from the operating position to the retracted position. The above-mentioned object is easily achieved by making the outer diameter relatively thick and making the outer diameter relatively small in the region that does not directly contribute to the support of the latent image writing device.

  As a fourth feature, the connecting member between the support members has a length of the first support region of the latent image writing device with respect to a direction spanning between the first support member and the second support member. It is preferable that the length of the second support area of the latent image writing device is shorter.

  The problem of the fourth feature is that a higher effect can be obtained with respect to the vibration displacement suppressing effect of the latent image writing device support section.

  The fourth feature is that the relative bending rigidity of the support shaft of the latent image writing device can be further increased by shortening the axial length of the support region. By bringing the support of the apparatus close to the connecting portion between the support shaft and the housing, the latent image writing device can be supported in a place where the deformation amount due to the vibration of the support shaft is small.

  As a fifth feature, it is preferable that the support member-to-support member connecting member includes vibration damping means connected to the latent image writing device second support region.

  The purpose of the fifth feature is to obtain an efficient damping effect by providing vibration damping means in a region that does not directly contribute to support of the latent image writing apparatus in which vibration is concentrated.

  The effect of the fifth feature is that the generated vibration can be attenuated early.

  The fifth feature is that the vibration energy transmitted to the vibration attenuating means is concentrated by providing the vibration attenuating means in the locally concentrated vibration part. Thereby, the vibration damping means can efficiently absorb vibration energy and obtain a high damping effect.

  As a sixth feature, it is preferable that the vibration damping means is a substantially cylindrical elastic member and is applied to the outer periphery of the inter-support member connecting member in the second support area of the latent image writing device.

  The purpose of the sixth feature is to provide a substantially cylindrical elastic member (anti-vibration rubber, etc.) that exhibits a damping effect by deformation in a portion with a large amount of deformation, aiming at a high damping effect and writing a latent image. The configuration is such that the support position accuracy of the apparatus is not adversely affected.

  The effect of the sixth feature is that the generated vibration can be attenuated at an early stage, and the support position accuracy of the latent image writing device can be ensured.

  The action of the sixth feature is that by applying anti-vibration rubber to the outer periphery of the region that does not directly contribute to the support of the latent image writing device having a thin outer diameter, the vibration is locally concentrated in this region, The deformation of the anti-vibration rubber is increased, and a high vibration damping effect can be exhibited. Further, the region directly contributing to the support of the latent image writing device is not covered with an anti-vibration rubber, and a rubber material having poor dimensional stability is not interposed between the latent image writing device and the support member. The target effect can be achieved without deteriorating the positioning stability of the writing device.

  As a seventh feature, the inter-support member connecting member includes a fixing auxiliary unit that fixes both the inter-support member connecting member and the first support member to a first connecting portion, and the fixing auxiliary unit includes: It is preferable that the connection strength between the connection member between the support members and the first support member is higher than the connection strength between the connection member between the support members and the second support member.

  The purpose of the seventh feature is to take a form that gives a relative difference in the connection strength of the support to the casing so as to further obtain a relative difference in rigidity in each region of the support.

  The function of the seventh feature is that a fixing auxiliary member is added to the connecting portion of the support to the housing in the region that directly contributes to the support of the latent image writing device, and the substantially complete fixing state is obtained. On the other hand, the connection part of the support body to the housing in the region that does not directly contribute to the support of the latent image writing device is in a substantially simple support state. Thereby, the bending rigidity in each area | region of a support body becomes remarkably high in the direction of a substantially completely fixed state area | region with respect to a substantially simple support state area | region, and can make a further local vibration concentration.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described herein with reference to specific embodiments, it will be understood that various modifications and changes may be made specifically without departing from the broader spirit and scope of the invention as defined in the claims. is there.

1Y, M, C, K process unit 2Y, M, C, K photoconductor 3K drum cleaning device 4K charging device 5K developing device 6K hopper unit 7K developing unit 8K agitator 9K stirring paddle 10K toner supply roller 11K developing roller 12K thinning Blade 15 Transfer unit 16 Intermediate transfer belt 17 Driven roller 18 Drive roller 19Y, M, C, K Primary transfer roller 20 Secondary transfer roller 21 Belt cleaning device 22 Cleaning backup roller 23 Residual toner collection device 30 Paper feed cassette 30a Paper feed Roller 31 Paper feed path 32 Registration roller pair 33 Conveyance path 34 Fixing device 34a Fixing roller 34b Pressure roller 35 Conveyance path 37 Discharge roller pair 50 Upper cover 70 Optical writing unit 70a Front positioning shaft 70b Rear positioning shaft 71 Left positioning protrusion 71a Polygon motor 71b Polygon mirror 72 Front cover frame 72a Front opening 73 Rear cover frame 73a Rear opening 74 Front pressing spring 75 Rear pressing spring 76 Holding spring 80 Front plate 81 Front positioning groove 90 Rear plate 91 Rear positioning Groove 100 Rotating shaft 100a Stepped portion 100b Left first support region 100c Left second support region 101 Left positioning portion 102 Anti-vibration rubber L Laser light P Recording paper

JP 2007-164141 A JP 2007-164128 A JP 2007-192894 A JP 2000-111822 A JP 2007-133252 A

Claims (7)

An image carrier carrying a latent image on the surface;
A first support member that supports one end of the image carrier;
A second support member for supporting the other end side of the image carrier;
A support member connecting member that bridges the first support member and the second support member;
A latent image writing device that is movable between an operation position for performing an exposure operation and a retracted position for not performing the exposure operation, and at least one end of which is supported by the inter-support member connecting member,
The connecting member between the support members is flexible and includes a latent image writing device first support region and a latent image writing device second support region, and the latent image writing device first support region. And the latent image writing device second support region have different elastic moduli. The supporting member connecting member is
A latent image writing device first support region from a connecting portion with the first support member to a first latent image writing device support portion on which the latent image writing device is supported;
A latent image writing device second support region from a connecting portion with the second support member to a front side of the first latent image writing device support portion where the latent image writing device is supported is connected. ,
The latent image writing device has a bending stiffness K1 and a mass per unit length M1 in the first support region of the latent image writing device with respect to the direction in which the first support member and the second support member are bridged. When the bending stiffness in the second support region is K2, and the mass per unit length is M2, K1 / M1> K2 / M2,
The first latent image writing device support section includes a connection portion between the latent image writing device first support area and the latent image writing apparatus second support area and the vicinity of the latent image writing apparatus first support area side. The image forming apparatus according to claim 1.   The inter-support member connecting member is an inter-support member shaft member integrally formed as a support shaft when the latent image writing device rotates and moves between the operating position and the retracted position. 3. The image forming apparatus according to claim 1, wherein an outer diameter of the first support area of the image forming device is larger than an outer diameter of the shaft member between the support portions in the second support area of the latent image writing apparatus. .   The inter-support member connecting member is configured to set the length of the first support area of the latent image writing device to the latent image writing direction in a direction spanning between the first support member and the second support member. The image forming apparatus according to claim 1, wherein the image forming apparatus is shorter than a length of the second support region of the apparatus.   5. The image forming apparatus according to claim 1, wherein the connecting member between supporting members includes a vibration damping unit connected to the second support area of the latent image writing device. 6. The image according to claim 5, wherein the vibration damping means is a substantially cylindrical elastic member and is covered on an outer periphery of the inter-support member connecting member in the second support area of the latent image writing device.

Image forming apparatus. The connecting member between support members includes a fixing auxiliary means for fixing both the connecting member between support members and the first supporting member to a first connecting part,
The fixing auxiliary means is characterized in that the connection strength between the connection member between the support members and the first support member is higher than the connection strength between the connection member between the support members and the second support member. Item 7. The image forming apparatus according to any one of Items 1 to 6.

Images