Patent Application
20200387080
The present disclosure relates to image forming apparatuses, such as copying machines and printers, that form an image on a recording sheet using an electrophotographic method.
There is an electrophotographic image forming apparatus with an optical scanning apparatus that emits laser light to a charged surface of a photosensitive drum to form an electrostatic latent image on the photosensitive drum. The optical scanning apparatus includes a light source, optical system components, such as a rotary polygon mirror that deflects a light beam emitted from the light source, a mirror, and a lens, and an optical box that is a housing to cover the optical system components.
The optical scanning apparatus is controlled by a control unit of the image forming apparatus. A control signal for controlling the optical scanning apparatus is transmitted from the control unit to the optical scanning apparatus through a flexible flat cable (FFC). The flexible flat cable includes a plurality of conductive lines. The conductive lines emit electromagnetic wave noise. The electromagnetic wave noise can cause driving of the image forming apparatus to become unstable to lead to poor image forming. For example, Japanese Patent Application Laid-Open No. 2012-247510 discusses a cable that is connected to a substrate on a side wall of an optical scanning apparatus. A control signal is transmitted from a main body apparatus to the optical scanning apparatus through the cable.
In some image forming apparatuses, an optical scanning apparatus is situated to face a rear plate that constitutes a portion of a housing of a main body of the image forming apparatus. For example, Japanese Patent Application Laid-Open No. 2002-287063 discusses a structure in which a front side of an optical scanning apparatus is screwed to a front plate and a back surface side is fixed to a rear plate via a plate spring. With this structure, the optical scanning apparatus is maintained in a state of being fixed to a housing of a main body of an image forming apparatus at a position facing the rear plate.
In some image forming apparatuses, a metal rear plate in a grounded state is situated on a back surface side of a main body of the image forming apparatus. In a case where an optical scanning apparatus is attached to an apparatus body at a position facing a rear plate, a flexible flat cable extending from the optical scanning apparatus toward a control unit is sometimes arranged near the rear plate.
However, even with this structure, the rear plate and the flexible flat cable are not maintained in a state of being reliably in contact with each other. Thus, electromagnetic wave noise can be emitted from the flexible flat cable and causes poor image forming.
According to an aspect of the present disclosure, an image forming apparatus includes a metal rear plate on a back surface side of the image forming apparatus and grounded, a photosensitive drum, an optical box attached to a position facing the rear plate through an opening of a side surface of the image forming apparatus, the optical box including a substrate that includes a connector and a light source configured to emit a light beam to which the photosensitive drum is exposed, a flexible flat cable connected to the connector and configured to transmit a signal to drive the substrate, and a guide member configured to curve the flexible flat cable toward the side surface and guide the flexible flat cable toward the side surface along a wall portion of the rear plate that faces the optical box in a front-rear direction, the flexible flat cable extending from the connector toward the wall portion, and the guide member being on the wall portion, wherein a first virtual line is defined as a perpendicular line from the connector to the wall portion and a second virtual line is defined as a perpendicular line from the guide member to the first virtual line, and wherein a distance from a connection portion of the flexible flat cable that is connected to the connector to a portion of the flexible flat cable that is guided by the guide member is longer than a sum of a length of the first virtual line and a length of the second virtual line, and the flexible flat cable guided by the guide member is in contact with the wall portion.
Further features and aspects of the present disclosure will become apparent from the following description of example embodiments with reference to the attached drawings.
An example embodiment of the present disclosure will be described below with reference to the drawings. Unless otherwise specified, sizes, materials, shapes, and relative positions of below-described components are not intended to limit the scope of the disclosure thereto.
The image forming apparatus 1 includes an intermediate transfer belt 20 onto which the respective toner images formed by the image forming units 10Y, 10M, 10C, and 10Bk (hereinafter, also referred to simply as “image forming unit 10”) are transferred. The intermediate transfer belt 20 transfers the toner images transferred from the image forming units 10 onto a recording sheet P. The image forming units 10Y, 10M, 10C, and 10Bk have a substantially similar structure except for the colors of toners used by the respective image forming units 10. Hereinafter, the image forming unit 10Y will be described as an example of the image forming unit 10. Overlapped descriptions of the image forming units 10M, 10C, and 10Bk are omitted.
The image forming unit 10Y includes the photosensitive drum 50Y, a charging roller 12Y, a development device 13Y, and a primary transfer roller 15Y. The charging roller 12Y uniformly charges the photosensitive drum 50Y. The development device 13Y develops an electrostatic latent image formed on the photosensitive drum 50Y by an optical scanning apparatus, which will be described below, using the toner and forms a toner image. The primary transfer roller 15Y transfers the formed toner image to the intermediate transfer belt 20. A primary transfer portion is formed by the primary transfer roller 15Y and the photosensitive drum 50Y with the intermediate transfer belt 20 therebetween. A predetermined transfer voltage is applied to the primary transfer roller 15Y so that the toner image formed on the photosensitive drum 50Y is transferred onto the intermediate transfer belt 20.
The intermediate transfer belt 20 is an endless belt stretched around a first belt conveyance roller 21 and a second belt conveyance roller 22 and is rotated in the direction of an arrow H. The toner images formed by the image forming units 10Y, 10M, 10C, and 10Bk are transferred onto the intermediate transfer belt 20 being rotated. The four image forming units 10 are arranged parallel to each other and vertically under the intermediate transfer belt 20. With this arrangement, the toner images formed on the photosensitive drum 50 based on image information about the respective colors are transferred onto the intermediate transfer belt 20.
Further, the first belt conveyance roller 21 and a secondary transfer roller 60 are pressed against each other with the intermediate transfer belt 20 therebetween. With this arrangement, a secondary transfer portion is formed by the first belt conveyance roller 21 and the secondary transfer roller 60 with the intermediate transfer belt 20 therebetween. The recording sheet P is inserted into the secondary transfer portion, and the toner images are transferred from the intermediate transfer belt 20 onto the recording sheet P. The untransferred toner that remains on the surface of the intermediate transfer belt 20 is collected by a cleaning apparatus (not illustrated).
The image forming units 10Y, 10M, 10C, and 10Bk, which respectively form yellow, magenta, cyan, and black toner images, are arranged in this order from an upstream side with respect to the secondary transfer portion in a rotation direction (the direction of the arrow H) of the intermediate transfer belt 20.
Vertically under the image forming units 10 is situated the optical scanning apparatus that scans laser light (light beam) over each of the photosensitive drums 50 corresponding to the respective colors and forms an electrostatic latent image on a surface of each of the photosensitive drums 50.
The optical scanning apparatus herein includes the optical scanning apparatus 40, a rotary polygon mirror (not illustrated), and a reflection mirror (not illustrated). Further, the optical scanning apparatus 40 contains optical members such as a rotary polygon mirror 42 and a reflection mirror 62. The optical scanning apparatus 40 according to the present example embodiment includes four semiconductor lasers (not illustrated) that emit laser light beams modulated based on the image information about the respective colors. The plurality of semiconductor lasers is light sources that expose the respective corresponding photosensitive drums 50. The rotary polygon mirror 42 is rotated at high speed by a polygon motor (not illustrated). In this way, the laser light beams emitted from the semiconductor lasers are reflected to scan the photosensitive drums 50 along a rotation axis direction (main scan direction) of the photosensitive drums 50. Each laser light beam emitted from the semiconductor lasers and reflected by the rotary polygon mirror 42 is guided to an optical system component, such as a lens, in the optical scanning apparatus 40 and is emitted from the inside to the outside of the optical scanning apparatus 40 through a transmission member covering an exit opening at the top of the optical scanning apparatus 40. The respective laser light beams emitted from the optical scanning apparatus 40 expose the photosensitive drums 50.
While the single optical scanning apparatus 40 emits a light beam to each of the four photosensitive drums 50 in the present example embodiment, example embodiments are not limited to the present example embodiment. Each of the four image forming units 10 may include the optical scanning apparatus 40 to emit a single light beam from each optical scanning apparatus 40 to the single corresponding photosensitive drum 50.
Meanwhile, the recording sheet P is stored in a sheet feeding cassette 2 situated in a lower part of the image forming apparatus 1. The recording sheet P is fed by a pickup roller 24 to a separation nip portion formed by a sheet feeding roller 25 and a retard roller 26. Driving is transmitted such that the retard roller 26 is rotated backward when the plurality of recording sheets P is fed by the pickup roller 24. In this way, the plurality of recording sheets P is singly conveyed to prevent feeding of more than one recording sheet P at the same time. The recording sheet P that is singly conveyed by the sheet feeding roller 25 and the retard roller 26 is conveyed to a conveyance path 27 extending substantially vertically along a right side surface of the image forming apparatus 1.
Then, the recording sheet P is vertically conveyed from the bottom of the image forming apparatus 1 toward the top through the conveyance path 27 to a registration roller 29. The registration roller 29 stops the conveyed recording sheet P and corrects the recording sheet P that is skewed. Thereafter, the registration roller 29 conveys the recording sheet P to the secondary transfer portion in synchronization with the timing at which the toner images on the intermediate transfer belt 20 are conveyed to the secondary transfer portion. Thereafter, the recording sheet P with the toner images transferred thereto at the secondary transfer portion is conveyed to a fixing device 3 and heated and pressed by the fixing device 3 so that the toner images are fixed to the recording sheet P. Then, the recording sheet P with the fixed toner images is discharged onto a sheet discharge tray 420 by a sheet discharge roller 28. The sheet discharge tray 420 is situated outside the image forming apparatus 1 and at the top of the main body of the image forming apparatus 1.
As described above, in full-color image forming by the image forming apparatus 1 according to the present example embodiment, the optical scanning apparatus 40 exposes the photosensitive drums 50Y, 50M 50C, and 50Bk of the image forming units 10 at respective predetermined timings based on image information about the respective colors. Consequently, toner images of the respective colors based on the image information about the respective colors are formed on the respective photosensitive drums 50. To acquire a high-quality full-color image, the positions at which the respective electrostatic latent images are formed by the optical scanning apparatus 40 are reproduced with high accuracy.
Further, a rear side plate 53 is situated on a back surface side of the apparatus body 100. The optical box 80 attached to the attachment portion 440 through the opening 419 is situated to face the rear plate 53.
The rotary polygon mirror 42 and a scanner motor 41 are attached to the bottom surface of the optical box 80. The rotary polygon mirror 42 deflects a laser light beam emitted from the light source 51. The scanner motor 41 rotates the rotary polygon mirror 42. The rotary polygon mirror 42 is a polygon mirror that rotates about a rotation axis. A laser light beam emitted from the light source 51 is reflected by the rotary polygon mirror 42, and the laser light beam reflected by the rotary polygon mirror 42 travels toward the photosensitive drum 50 that is a surface to be scanned. Further, a laser light beam emitted from the light source 51a is reflected by the rotary polygon mirror 42, and the reflected laser light beam travels toward the light reception sensor 59 mounted on the circuit substrate 45.
The length of time from a timing at which the light reception sensor 59 receives a laser light beam to a start of forming a latent image on the photosensitive drum 50 by the laser light beam is desirably kept constant during operation. The light reception sensor 59 is arranged to keep the length of time constant during operation. Specifically, the light reception sensor 59 is used to determine a timing to emit a laser light beam from the light sources 51a to 51d. The light reception sensor 59 is situated immediately above the light source 51a (chip holder 46a). A laser light beam traveling toward the light reception sensor 59 and a laser light beam emitted from the light source 51a do not have an angle difference in the main scan direction. Meanwhile, the optical scanning apparatus 40 includes the plurality of light sources 51. For example, the light sources 51a and 51b, which are an example of a first light source, and the light sources 51c and 51d, which are an example of a second light source, are respectively arranged on right and left sides based on a plane that is perpendicular to a rotation axis of the rotary polygon mirror 42. For example, the optical paths of laser light beams that are respectively emitted from the light sources 51a and 51b, which are the two light sources arranged on one side, each have an angle difference (β) in the main scan direction (refer to
When the circuit substrate 45 is attached to the side wall portion 101d of the optical scanning apparatus 40, the chip holders 46a and 46b extend toward the inside of the optical scanning apparatus 40. Thus, the optical box 80 includes a partition portion (hereinafter, referred to as “case portion 101b”) having a shape to cover the light source 51. The side wall portion 101d of the optical box 80 to which the circuit substrate 45 is attached includes an opening 101c so that a laser light beam emitted from the light source 51 is guided to the rotary polygon mirror 42. The inside and the outside of the optical scanning apparatus 40 are connected through the opening 101c. In other words, air outside the optical scanning apparatus 40 can enter the optical scanning apparatus 40 through the opening 101c. Thus, it is desirable to seal the opening 101c with a sealing member that seals the opening 101c. In the present example embodiment, a cylindrical lens 65 also functions as the sealing member that seals the opening 101c. The opening 101c is at an end of the case portion 101b where the sealing member can be placed with ease. The case portion 101b is a partition that separates the inside and the outside of the optical scanning apparatus 40. The opening 101c is formed such that a laser light beam emitted from the light source 51a travels from the outside of the optical box 80 into the optical box 80 through the opening 101c. Further, the opening 101c is formed to allow a laser light beam to travel from the inside to the outside of the optical box 80 through the opening 101c so that the laser light beam reflected by the rotary polygon mirror 42 is received by the light reception sensor 59. The case portions 101b include seats 70d and 70g on which an optical component is to be placed.
How laser light beams are guided to the photosensitive drums 50 by the optical lenses 60a to 60f and the reflection mirrors 62a to 62h will be described below with reference to
A laser light beam LM emitted from the light source 51b and corresponding to the photosensitive drum 50M is deflected by the rotary polygon mirror 42, and the deflected laser light beam LM enters the optical lens 60a. The laser light beam LM having traveled through the optical lens 60a is reflected by the reflection mirrors 62b and 62c, and the reflected laser light beam LM enters the optical lens 60e, travels through the optical lens 60e, and then is reflected by the reflection mirror 62d. The laser light beam LM reflected by the reflection mirror 62d travels through a transparent window (not illustrated) and scans across the photosensitive drum 50M. Each laser light beam emitted from the light sources 51a and 51b and deflected by the rotary polygon mirror 42 first enters the optical lens 60a among the plurality of optical members.
A laser light beam LC emitted from the light source 51c and corresponding to the photosensitive drum 50C is deflected by the rotary polygon mirror 42, and the deflected laser light beam LC enters the optical lens 60c. The laser light beam LC having traveled through the optical lens 60c is reflected by the reflection mirrors 62e and 62f, and the reflected laser light beam LC enters the optical lens 60f, travels through the optical lens 60f, and then is reflected by the reflection mirror 62g. The laser light beam LC reflected by the reflection mirror 62g travels through a transparent window (not illustrated) and scans across the photosensitive drum 50C.
A laser light beam LBk emitted from the light source 51d and corresponding to the photosensitive drum 50Bk is deflected by the rotary polygon mirror 42, and the deflected laser light beam LBk enters the optical lens 60c. The laser light beam LBk having traveled through the optical lens 60c enters the optical lens 60d, travels through the optical lens 60d, and is then reflected by the reflection mirror 62h. The laser light beam LBk reflected by the reflection mirror 62h travels through the transparent window (not illustrated) and scans across the photosensitive drum 50Bk. Each laser light beam emitted from the light sources 51c and 51d and deflected by the rotary polygon mirror 42 first enters the optical lens 60c among the plurality of optical members.
In order to minimize the size of the optical box 80, the optical scanning apparatus 40 has a structure as described below. The size of the optical box 80 is determined such that the reflection mirror 62 is long enough to guide each laser light beam to a scan surface and the optical box 80 has the smallest possible size to house the reflection mirror 62. In the optical box 80 with this size, the light source 51 is arranged to fit the side wall portion 101d of the optical box 80. In this way, the size of the entire optical scanning apparatus 40 is reduced.
In the present example embodiment, for example, the light source 51 that has an outer diameter of φ11.6 and includes eight light emitting points is used. In arranging the light sources 51 at the side wall portion 101d of the optical box 80, it is desirable to arrange the light sources 51 such that the two light sources 51 have a great angle difference, in order to prevent interference between two circuit substrates 45 in a case where the two light sources 51 on the same circuit substrate 45 have an angle difference only in the sub-scan direction (upward and downward directions). The angle difference between the two light sources 51 refers to an angle that is formed by optical paths 511a and 511b. The optical path 511a is an optical path of a laser light beam emitted from the light source 51a, and the optical path 511b is an optical path of a laser light beam emitted from the light source 51b. If the angle difference between the optical paths 511a and 511b of the two light sources 51 in the sub-scan direction increases, a reflection surface of the rotary polygon mirror 42 departs from an ideal position, and this increases errors of positions at which laser light beams arrive on the photosensitive drum 50. Consequently, image quality decreases. For example, decentering of the rotary polygon mirror 42 causes an irradiation position of a laser light beam on the photosensitive drum 50 to deviate.
In order to reduce the angle difference between the optical paths 511a and 511b of the two the light sources 51a and 51b in the sub-scan direction, the circuit substrate 45 is assumed to be situated away from the rotary polygon mirror 42. In this case, the side wall portion 101d of the optical scanning apparatus 40 on which the circuit substrate 45 is to be situated needs to be away from the rotary polygon mirror 42. In other words, the size of the optical box 80 in a front-rear direction increases. Thus, in order to minimize the size of the optical scanning apparatus 40 while maintaining adequate image quality, the circuit substrate 45 is arranged to have an angle difference also in the main scan direction and emit laser light beams. Thus, the side wall portion 101d of the optical box 80 can be situated near the rotary polygon mirror 42, and the size of the optical box 80 in a Y-axis direction is reduced. An angle β that is a second angle specified in
As illustrated in
The control signal is transmitted from the control unit to the circuit substrates 45a and 45b to control driving of the optical scanning apparatus 40. In this way, a desired latent image is formed on the photosensitive drum 50.
Further, as illustrated in
The rear plate 53 and the connector 58 are arranged to face each other so that the flexible flat cable 54 extends from the connector 58 toward the rear plate 53 and comes into contact with the rear plate 53. Details thereof will be described below. The flexible flat cable 54 is flexible, so that when the flexible flat cable 54 is in a curved state, a force to elongate is exerted on the flexible flat cable 54. Thus, a force to cancel the curved state is exerted on the flexible flat cable 54 curved near the rear plate 53, and the flexible flat cable 54 is pressed toward the rear plate 53, and the flexible flat cable 54 and the rear plate 53 come into contact with each other. The flexible flat cable 54 is brought into contact with the rear plate 53, which is made of a metal and grounded, so that the flexible flat cable 54 is also grounded. In this way, electromagnetic wave noise from the flexible flat cable 54 is reduced.
Methods of reducing electromagnetic wave noise from the flexible flat cable 54 are not limited to the above-described method in which a portion of the flexible flat cable 54 is brought into contact with the rear plate 53 that is grounded, and there is also a method in which, for example, each flexible flat cable 54 is covered with a metal plate. For example, a metal plate similar to the rear plate 53 can be arranged on the right and left sides of the optical box 80 so that the metal plates are on the front, rear, left, and right sides of the flexible flat cable 54. This method, however, has issues that installation of the new metal plates increases costs and the weight of the image forming apparatus 1 increases. With a method in which a holding member 55 (an example of a guide member) is placed in front of a wall portion 53a of the rear plate 53 and a portion of the flexible flat cable 54 is brought into contact with the rear plate 53 as in the present example embodiment, noise is controlled at low cost.
Further, electromagnetic wave noise emitted from the flexible flat cable 54 can affect the other electronic components in the apparatus body 100 and can also affect other electronic devices outside the apparatus body 100. With the method according to the present example embodiment of the present disclosure, electromagnetic wave noise that is emitted to the outside of the image forming apparatus 1 is also reduced.
Although hidden and not visible in
The flexible flat cable 54 extending from the connector 58 of the circuit substrate 45a toward the wall portion 53a is bent near the wall portion 53a toward the opening 419 and forms a curved portion C1. The flexible flat cable 54 that forms the curved portion C1 and extends toward the opening 419 is held on the rear plate 53 by the holding member 55 attached to the rear plate 53. The flexible flat cable 54 guided by the holding member 55 to be cabled along the wall portion 53a is bent along the shape of the rear plate 53 and extends along the wall portion 53b to the control unit of the apparatus body 100. Since the flexible flat cable 54 has flexibility, a force to elongate is exerted on the flexible flat cable 54 when the flexible flat cable 54 is curved, so that a portion of the flexible flat cable 54 in the vicinity of the curved portion C1 is pressed against the wall portion 53a of the rear plate 53.
Alternatively, the flexible flat cable 54 can be bent in the vicinity of the wall portion 53a of the rear plate 53 from the connector 58 toward the opening 419 and the bent line portion can be brought into contact with the rear plate 53. The bent line is formed as described above to realize more stable cabling along the wall portion 53a of the rear plate 53. At this time, the holding member 55 may guide the flexible flat cable 54 so that the bent line comes into contact with the wall portion 53a of the rear plate 53.
In the present example embodiment, the holding member 55 is fixed to the wall portion 53a of the rear plate 53. In this way, the flexible flat cable 54 is supported at a position facing the wall portion 53a. A function of the holding member 55 is to hold the flexible flat cable 54 along the wall portion 53a at a position facing the wall portion 53a. As illustrated in
Further, it is desirable, but not required, that the holding member 55 should have a function of fixing the flexible flat cable 54 to the rear plate 53. In the present example embodiment, the holding member 55 merely guides the flexible flat cable 54 along the wall portion 53a to maintain the state where the flexible flat cable 54 extending from the connector 58 to the wall portion 53a is in contact with the wall portion 53a.
To simplify description, the flexible flat cable 54 is divided into three regions 54a, 54b, and 54c as illustrated in
In the present example embodiment, the distance of the surface 54a in a lengthwise direction of the flexible flat cable 54 is set longer than the distance from the connector 58 to the wall portion 53a. Thus, the flexible flat cable 54 is in contact with the wall portion 53a at the curved portion C1, and the surface 54a is slightly curved. The holding member 55 holds the flexible flat cable 54 on the rear plate 53 in order to maintain the state of the flexible flat cable 54 in the above-described state. The holding member 55 holds the flexible flat cable 54 so that the contact state in which the flexible flat cable 54 and the rear plate 53 are in contact with each other is maintained, and the flexible flat cable 54 is reliably grounded.
The holding member 55 includes two arms that are an upper arm portion 55a and a lower arm portion 55b. The upper arm portion 55a holds the flexible flat cable 54 to clutch the flexible flat cable 54 from vertically above. Further, the lower arm portion 55b holds the flexible flat cable 54 to clutch the flexible flat cable 54 from vertically below. A main role of the lower arm portion 55b is to support the flexible flat cable 54.
In the present example embodiment, the flexible flat cable 54 is held by being sandwiched between the upper arm portion 55a and the wall portion 53a. In this way, the flexible flat cable 54 is guided by the holding member 55.
For example, in the present example embodiment, the state where the flexible flat cable 54 “is guided” by the holding member 55 refers to a state where the flexible flat cable 54 is held by the holding member 55.
A state where, for example, the flexible flat cable 54 is not held by the upper arm portion 55a and is supported by the lower arm portion 55b is also considered as the state where the flexible flat cable 54 is guided by the holding member 55.
The state where the flexible flat cable 54 “is guided” by the holding member 55 is not limited to a state where the flexible flat cable 54 is held or supported by the holding member 55. To guide the flexible flat cable 54, the holding member 55 is brought into contact with the flexible flat cable 54 to direct a cabling direction of the flexible flat cable 54. In this case, a contact portion of the holding member 55 and the flexible flat cable 54 corresponds to a portion that is guided by the holding member 55.
The upper arm portion 55a and the lower arm portion 55b may both press the flexible flat cable 54 against the wall portion 53a of the rear plate 53. In this case, not only the curved portion C1 of the flexible flat cable 54 but also a portion of the flexible flat cable 54 that is held by the holding member 55 are in contact with the wall portion 53a of the rear plate 53. The upper arm portion 55a presses one of the surfaces of the surface 54b of the flexible flat cable 54 that is opposite to the surface facing the wall portion 53a, whereby the flexible flat cable 54 is brought into contact with the wall portion 53a. A minimal function of the holding member 55 is the function of holding the flexible flat cable 54, so that the holding member 55 does not have to include the function of bringing the flexible flat cable 54 into contact with the wall portion 53a of the rear plate 53. For example, the holding member 55 may hold the flexible flat cable 54 by sandwiching the front and back surfaces of the flexible flat cable 54. The flexible flat cable 54 is arranged not to move with respect to the rear plate 53 so that the contact state where the flexible flat cable 54 is in contact with the wall portion 53a of the rear plate 53 at the curved portion C1 is maintained.
As illustrated in
As illustrated in
The surface 54a of the flexible flat cable 54, which is the region from the connection portion that is connected to the connector 58 to the contact portion that is in contact with the wall portion 53a of the rear plate 53, is curved to the right side of the apparatus body 100 from the line segment QS. Specifically, the length of the surface 54a in the lengthwise direction of the flexible flat cable 54 is longer than a length X1 of the line segment QS. Thus, the surface 54a is curved and is in contact with the wall portion 53a of the rear plate 53. In the present example embodiment, the flexible flat cable 54 has a flexural strength of 100 MPa or greater. Thus, the flexible flat cable 54 extending from the connector 58 is always in a state of being pressed against the wall portion 53a of the rear plate 53 and the shape of the flexible flat cable 54 is maintained in this state. While the value of 100 MPa or greater is described as an example of the flexural strength of the flexible flat cable 54 in present example embodiment, even in a case where the flexural strength is less than the above-described value, if the length of the surface 54a of the flexible flat cable 54 is longer than the length X1, which is the distance of the line segment QS, the flexible flat cable 54 being curved attempts to elongate, so that the flexible flat cable 54 comes into contact with the wall portion 53a of the rear plate 53.
Further, the distance from the portion of the flexible flat cable 54 that is held by the holding member 55 to the portion of the flexible flat cable 54 that is in contact with the wall portion 53a of the rear plate 53, i.e., the length of the surface 54b in the lengthwise direction of the flexible flat cable 54, is longer than a length X2 of the line segment PR. In order to reliably bring a portion of the flexible flat cable 54 into contact with the wall portion 53a of the rear plate 53, the shape of the flexible flat cable 54 is maintained such that (1) the length of the surface 54a in the lengthwise direction of the flexible flat cable 54 is longer than the length X1 of the line segment QS and (2) the length of the surface 54b in the lengthwise direction of the flexible flat cable 54 is longer than the length X2 of the line segment PR. Thus, in the present example embodiment, the flexible flat cable 54 is guided by the holding member 55 such that the length from the portion of the flexible flat cable 54 that is held by the holding member 55 to the connection portion of the flexible flat cable 54 that is connected to the connector 58 is longer than the sum of X1+X2, which is the sum of the length X2 of the line segment PR and the length X1 of the line segment QS.
A material of the rear plate 53 is a metal (iron). Thus, the rear plate 53 is used as an electrical ground of the image forming apparatus 1. The rear plate 53 as the ground reduces noise emission. Thus, the flexible flat cable 54 is brought into contact with the noise-reducing member so that noise emission from the flexible flat cable 54 is reduced. Further, especially the optical scanning apparatus 40 easily emits noise because high-speed signals are input to the optical scanning apparatus 40. Thus, the state where the flexible flat cable 54 connected to the circuit substrate 45a of the optical scanning apparatus 40 is in contact with the rear plate 53 is effective for noise reduction.
Further, there is a type of the flexible flat cable 54 that is with a shield. In the flexible flat cable 54 that is with the shield, a resin sheet covering both sides of a conductor is covered with a metal foil sheet in order to reduce an effect of electric signal noise on an electric signal that is transmitted through the conductor of the flexible flat cable 54. Even in a case where the flexible flat cable 54 with the shield is used, the flexible flat cable 54 is reliably grounded if the flexible flat cable 54 is guided by the holding member 55 such that a portion of the flexible flat cable 54 is brought into contact with the metal rear plate 53.
As illustrated in
In the optical scanning apparatus 40 of the facing scanning system, the rotary polygon mirror 42 is situated in the vicinity of a center of the optical box 80. Thus, the circuit substrates 45a and 45b on which the light sources 51a, 51b, 51c, and 51d that emit a light beam toward the rotary polygon mirror 42 are provided are also situated close to each other in the vicinity of the center of the optical box 80 in the rightward and leftward directions. Thus, the connector 58 attached to the circuit substrate 45a is not situated, for example, near a left end portion of the optical box 80, i.e., near the opening 419 in a state where, the optical scanning apparatus 40 is attached to the apparatus body 100. Thus, the connector 58 is situated closer to the right side of the apparatus body 100 than the holding member 55 is.
There are not only the optical scanning apparatuses of the facing scanning system described above but also the optical scanning apparatuses of a one-side scanning system. The term “one-side scanning system” refers to a system in which a light beam incident on the rotary polygon mirror 42 is deflected to one side by the rotary polygon mirror 42 being rotated.
In the optical scanning apparatus 40 of the one-side scanning system, for example, the rotary polygon mirror 42 is situated near the left end of the optical box 80. Therefore, a circuit substrate on which a light source that emits a light beam toward the rotary polygon mirror 42 is mounted is also situated close to the left side of the optical box 80 in the rightward and leftward directions. Thus, a connector attached to the circuit substrate can be situated near the left end portion of the optical box 80, i.e., near the opening 419 in a state where the optical scanning apparatus 40 is attached to the apparatus body 100. Specifically, the connector can be situated on the left side of the holding member 55. In other words, the connector 58 is situated upstream of the holding member 55 in the direction of attachment of the optical box 80 to the apparatus body 100. Even in this case, the flexible flat cable 54 is still brought into contact with the wall portion 53a of the rear plate 53 by defining the distance of the length X1 and the length of the surface 54a and defining the distance of the length X2 and the length of the surface 54b as described above with reference to
The descriptions of the example embodiment described above are mere examples in all aspects and are not limitative. For example, the connector 58 may be attached to the circuit substrate 45a such that the lengthwise direction of the connector 58 is perpendicular to the vertical direction. In this case, the flexible flat cable 54 extends from the connector 58 toward the wall portion 53a of the rear plate 53 with one of the surfaces of the flexible flat cable 54 facing vertically upward. Then, the flexible flat cable 54 comes into contact with the wall portion 53a, is folded several times, and is then cabled toward the opening 419. The length of the flexible flat cable 54 from the connection portion that is connected to the connector 58 to the contact portion that is in contact with the wall portion 53a is set longer than the direct distance between the connector 58 and the contact portion so that the flexible flat cable 54 is brought into contact with the wall portion 53a.
While the present disclosure has been described with reference to example embodiments, it is to be understood that the disclosure is not limited to the disclosed example embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-107373, filed Jun. 7, 2019, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-107373 | Jun 2019 | JP | national |
