JP2016039444A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of an image signal due to ESD with a simple configuration.SOLUTION: A copier 100 includes an image reading unit 201, an image forming unit 401, a document feeding unit 301, and a pair of opening/closing mechanisms 302, 303 arranged on a top face of a bottom member 212 along one end 212A of the bottom member 212. An image sensor substrate 221 and an image processing substrate 402 are connected to each other with a cable 251. A facing member 280 electrically connecting to the bottom member 212 and a housing 411 is arranged opposite the cable 251. A conductive extension member 290 is arranged near the opening/closing mechanism 302 so as to electrically connect to the opening/closing mechanism 302. The extension member 290 is extended in an arrow Z direction so as to be distanced from the opening/closing mechanism 302. A far end formed in the arrow Z direction far from the opening/closing mechanism 302 is opened.SELECTED DRAWING: Figure 2

Description

  The present invention includes an image reading unit having an image reading unit for reading an original image and an image forming unit having an image processing unit for processing an image signal from the image reading unit, and the image reading unit and the image processing unit are connected by a cable. The present invention relates to an image forming apparatus configured to be connected by.

  The image forming apparatus includes an image reading unit having an image reading unit that reads an image formed on a document, and an image forming unit having an image forming unit that forms an image on a sheet, and the image reading unit is provided on the image forming unit. Is arranged. The image reading unit is configured by a printed circuit board (image sensor substrate) having a photoelectric conversion element that captures image information by exposing and scanning an original.

  The image forming unit is disposed on a side surface of the casing and has an image processing unit that performs image processing. This image processing unit is configured by a printed circuit board (image processing board) in which a semiconductor device such as a CPU is mounted on a printed wiring board.

  The image reading unit and the image processing unit are connected by a cable, and the image processing unit acquires an image signal from the image reading unit via the cable. On the image reading unit, a document pressing plate for pressing the document to the document table is disposed, and the document pressing plate can be opened and closed by an opening / closing mechanism.

  In recent years, this document pressing plate is often incorporated in a document feeding unit that automatically supplies a document to the image reading unit. Therefore, since the opening / closing mechanism needs to be able to open and close the document feeding unit while supporting the document feeding unit which is a heavy object, the opening / closing mechanism is made of a conductive member such as metal.

  Since an image signal (digital signal) is transmitted to the cable connecting the image reading unit and the image processing unit, radiation noise from the cable that is generated when the image signal is transmitted must be suppressed.

  Therefore, the end of the lower side of the back side of the conductive housing of the image reading unit and the end of the upper side of the back side of the conductive housing of the image forming unit opposite to each other are connected by a conductive connecting member. A cable is placed on the member. This connecting member functions as a return current path for the signal current passing through the cable. Radiation noise from the cable is suppressed by bringing the cable close to the connection member.

  However, since the opening / closing mechanism is composed of a conductive member as described above and is a movable part, it is difficult to cover the entire structure with an exterior such as a resin member, and the conductive member is exposed. Accordingly, electrostatic discharge (ESD) is likely to enter the housing of the image reading unit from the opening / closing mechanism.

  Noise current due to ESD that has entered the housing of the image reading unit passes through the connection member and propagates to the housing of the image forming unit. At that time, noise current propagates to the cable due to electromagnetic coupling with the cable arranged near the connection member, and there is a possibility that the image signal transmitted by the cable is deteriorated. In recent years, the image signal has a very high transmission rate due to high-speed image reading and image formation of the image forming apparatus and high-definition image, and is easily affected by noise such as ESD. It is coming.

  On the other hand, a method has been proposed in which a cable is shielded to make it less susceptible to noise such as ESD (see Patent Document 1).

JP 2011-146150 A

  However, when the method of Patent Document 1 is applied to a cable that connects the image reading unit and the image processing unit of the image forming apparatus, there is a problem that the product cost increases. Further, when the image reading unit needs to move with respect to the original when reading the original, the cable through which the image signal is transmitted is required to have sliding and bending performance. However, since the shielded cable described in Patent Document 1 has a shield layer, the sliding bending performance is low, and it is difficult to adopt the shielded cable described in Patent Document 1 in a particularly thin image reading unit. .

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can suppress degradation of an image signal due to ESD with a simple configuration.

  An image forming apparatus according to the present invention includes a conductive bottom member, a document table placed above the bottom member, on which a document is placed, and an image reading unit that reads an image of the document placed on the document table An image reading unit including: an image processing unit that acquires an image signal and performs image processing; an image forming unit that forms an image on a sheet based on an image processing result by the image processing unit; and the image forming unit A pair of image forming units having a housed conductive housing; an opening / closing member that is opened and closed with respect to the document table; and a top surface of the bottom member, along one end of the bottom member, An opening / closing mechanism that supports the opening / closing member so that the opening / closing member can be freely opened and closed, wherein at least one of the pair is made of a conductive member, and the bottom member is placed between the pair of opening / closing mechanisms with the upper surface of the bottom member facing up. Pulled out to one end side, the bottom A transmission line that is bent at one end of the material in a first direction toward the image processing unit, connects the image reading unit and the image processing unit, and transmits an image signal from the image reading unit to the image processing unit An electrically conductive opposing member formed to extend in the first direction while facing the cable from one end of the bottom member and grounded to the housing, and to at least one opening / closing mechanism Provided in the vicinity of the at least one opening / closing mechanism so as to be electrically connected, and formed extending in the first direction so as to be away from the at least one opening / closing mechanism, and in the first direction with respect to the at least one opening / closing mechanism. A conductive extension member having a far end as an open end, and a first distance in a first direction between a lower end of the at least one opening / closing mechanism and an open end of the extension member is the facing portion A second distance in a second direction orthogonal to the first direction between an end side extending in the first direction on the side close to the extending member and a center line extending in the first direction of the at least one opening / closing mechanism. On the other hand, it is set to be 0.70 times or more and 1.30 times or less.

  According to the present invention, the noise current discharged to the bottom member of the image reading unit through the opening / closing mechanism is absorbed by the conductive extension member that is electrically conducted to one end of the bottom member of the image reading unit. Therefore, it is possible to suppress the noise current from flowing through the one end of the bottom member to the opposing member. As a result, the cable and the path through which the noise current flows can be separated, so that induction of noise in the cable due to electromagnetic coupling can be suppressed, and deterioration of the image signal propagating through the cable can be suppressed with a simple structure. .

1 is an explanatory diagram showing a schematic configuration of a copying machine as an example of an image forming apparatus according to a first embodiment of the present invention. 1 is a perspective view of a copying machine when a copying machine as an example of an image forming apparatus according to a first embodiment of the present invention is viewed from the back side. 1 is a partial rear view of a copying machine according to a first embodiment of the present invention. 5 is a graph showing a simulation result when ESD is applied to the copying machine according to the first embodiment of the present invention and a simulation result when ESD is applied to a copying machine of a comparative example. 5 is a graph showing a simulation result of voltage values received by the image processing board when the length of the extending member of the copying machine according to the first embodiment of the present invention is changed. 6 is a diagram for explaining a simulation result of voltage values received by the image processing board when the extending member of the copying machine according to the first embodiment of the present invention is offset in the second direction with respect to the support. FIG. . 6 is a graph showing a simulation result of voltage values received by the image processing board when the width of the extending member of the copying machine according to the first embodiment of the present invention is changed. FIG. 7 is a perspective view of a copying machine when a copying machine as an example of an image forming apparatus according to a second embodiment of the present invention is viewed from the back side. FIG. 9 is a perspective view of a copying machine when a copying machine as an example of an image forming apparatus according to a third embodiment of the present invention is viewed from the back side. It is a perspective view of a copying machine when the copying machine of a comparative example is seen from the back side.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is an explanatory diagram showing a schematic configuration of a copying machine as an example of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view of the copier when the copier as an example of the image forming apparatus according to the first embodiment of the present invention is viewed from the back side.

  As shown in FIGS. 1 and 2, the copying machine 100 as an image forming apparatus includes an image reading unit 201 and an image forming unit 401 disposed below the image reading unit 201. Further, the copying machine 100 includes a document feeding unit 301 as an opening / closing member disposed above the image reading unit 201.

  Further, as shown in FIG. 2, the copying machine 100 includes a pair of opening / closing mechanisms 302 and 303 that support the document feeding unit 301 so as to be openable and closable with respect to the image reading unit 201. The image forming unit 401 supports the image reading unit 201, and the image reading unit 201 supports the document feeding unit 301 via the opening / closing mechanisms 302 and 303.

  The image forming unit 401 includes a conductive (for example, metal) casing 411 as illustrated in FIG. 2, an image forming unit 420 that forms an image on a sheet (recording paper) as illustrated in FIG. A sheet feeding unit 430 that feeds the sheet to the forming unit 420. Further, the image forming unit 401 includes an image processing substrate 402 as an image processing unit as shown in FIGS. 1 and 2. Note that the housing 411 is preferably grounded to the ground G. The housing | casing 411 is formed in the substantially rectangular parallelepiped shape. The image forming unit 420 and the sheet feeding unit 430 are accommodated in the housing 411. The image processing board 402 is a printed circuit board having a semiconductor device such as a CPU and a printed wiring board on which the semiconductor device is mounted.

  The image reading unit 201 is attached to the image forming unit 401 and has a conductive (for example, metal) casing 213 as shown in FIG. The housing 213 includes a case 211 formed in a substantially rectangular parallelepiped shape, and a bottom member 212 that supports the case 211. The bottom member 212 is formed in a flat plate shape extending in the horizontal direction, and is larger than the outer shape of the case 211 when viewed from a direction perpendicular to the top surface of the bottom member 212. That is, the bottom member 212 is formed on the back side of the copying machine 100 so as to protrude from the case 211, and a part and one end (one side) 212 </ b> A of the bottom member 212 are exposed to the outside from the case 211.

  An opening is formed in the upper part of the case 211. The image reading unit 201 includes a platen glass 214 that is disposed in the opening of the case 211 and is supported by the case 211 as a document table. Therefore, the platen glass 214 is disposed above the bottom member 212 and spaced from the bottom member 212. The platen glass 214 is a transparent portion formed of a transparent member.

  Further, the image reading unit 201 has an image sensor substrate 221 as an image reading unit that moves relative to the document placed on the platen glass 214 (on the document table) and reads the document image. The image sensor substrate 221 is disposed between the bottom member 212 and the platen glass 214, that is, inside the case 211.

  The image sensor substrate 221 includes a line sensor (photoelectric conversion element) (not shown) such as a CCD image sensor or a CMOS image sensor, and a light emitting element (not shown) formed to extend in the direction of arrow Y, which is the main scanning direction. . The image sensor substrate 221 moves with respect to the document on the platen glass 214 by moving in the arrow X direction which is the sub-scanning direction (moving direction) intersecting (orthogonal) with respect to the arrow Y direction by a moving mechanism (not shown). To scan in the direction of arrow X. The ground conductor of the image sensor substrate 221 is arranged in a non-grounded state with respect to the bottom member 212.

  The image sensor substrate 221 and the image processing substrate 402 are electrically connected by a flexible cable 251 such as a flexible flat cable. This cable 251 serves as a transmission line for image signals. Specifically, one end 251A (FIG. 1) of the cable 251 is connected to the image sensor substrate 221 with a connector or the like, and the other end 251B of the cable 251 is connected to the image processing substrate 402 with a connector or the like. The cable 251 has a plurality of conductor lines. The image sensor substrate 221 performs signal processing for generating an image signal for signal transmission through the cable 251 based on the captured image information.

  An image signal generated by the signal processing of the image sensor substrate 221 is transmitted to the image processing substrate 402 via the cable 251. The image processing board 402 executes image processing for image formation based on the acquired image signal. The image processing substrate 402 controls the laser scanner 421 and the like of the image forming unit 420 shown in FIG. 1 based on the image processing result, scans the photosensitive drum 422, and forms a latent image. The toner image developed on the photosensitive drum 422 according to the latent image is transferred onto the fed and conveyed sheet, and is fixed on the sheet by passing through the fixing device 423 of the image forming unit 420. By the operation of the image forming unit 420 described above, a document image read by the image sensor substrate 221 is formed on the sheet.

  The document feeding unit 301 is an automatic document feeder (ADF) that sends a document to a position on the platen glass 214 where an image can be read by the image sensor substrate 221, and a document pressing plate 371 ( 1). When the document is fed by the document feeding unit 301, the image sensor substrate 221 is fixed at a fixed position, and the document image can be read by moving the document in the arrow X direction with respect to the image sensor substrate 221. . When the user directly places a document on the platen glass 214, the image sensor substrate 221 can read the document image by moving the image sensor substrate 221 in the arrow X direction with respect to the document. That is, the document image is read by the image sensor substrate 221 by moving the document in the arrow X direction relative to the image sensor substrate 221.

  Although the document feeding unit 301 is disposed as the opening / closing member, the opening / closing member may be formed of a document pressing plate that presses the document against the platen glass 214. The document feeding unit 301 is an automatic document feeding device that sends a document. However, the document feeding unit 301 itself may be provided with other functions such as an image reading unit. Further, as an option, the document feeding unit may be configured to be mountable instead of the document crimping plate.

  The pair of opening / closing mechanisms 302 and 303 are fixed on the upper surface of the bottom member 212 with a gap along one end 212 </ b> A on the back surface side of the bottom member 212. That is, since the bottom member 212 is formed on the back side of the copying machine 100 so as to protrude from the case 211, the pair of opening / closing mechanisms 302 and 303 are formed on the upper surface of the bottom member 212 at a portion exposed to the outside from the case 211. It is fixed. At least one opening / closing mechanism 302 of the pair of opening / closing mechanisms 302 and 303 is made of a conductive member, that is, a metal, in order to support the document feeding unit 301 which is a heavy object so as to be freely opened and closed. In the first embodiment, both opening / closing mechanisms 302 and 303 are made of conductive members, that is, metals. Therefore, both the opening / closing mechanisms 302 and 303 are electrically connected to the bottom member 212. Since the bottom member 212 supports the case 211, the opening / closing mechanisms 302 and 303 are electrically connected to the case 211 via the bottom member 212.

  The document feeding unit 301 is supported by a pair of opening / closing mechanisms 302 and 303 so as to be openable / closable with respect to the platen glass 214. When the document feeding unit 301 is in the open position, the platen glass 214 is exposed to the outside, and a user places a document on the platen glass 214 or a document on which the user is placed on the platen glass 214. Can be removed. When the document feeding unit 301 is in the closed position, the document fed onto the platen glass 214 is pressed against the platen glass 214 and light from the image sensor substrate 221 is prevented from leaking to the outside.

  The image processing substrate 402 is disposed outside the housing 411 and is accommodated in a box 403 disposed outside the housing 411. The ground conductor of the image processing substrate 402 is grounded to the housing 411 with the four corners connected to the housing 411. The box 403 is formed of a conductive member, that is, metal, and is electrically connected to the housing 411.

  As the image sensor substrate 221 moves in the direction of arrow X, one end 251A of the cable 251 moves in the direction of arrow X, so that the cable 251 is bent and deformed in the case 211 so as to be bent. This curved position moves according to the movement position of the image sensor substrate 221 in the arrow X direction.

  The cable 251 whose one end 251A is connected to the image sensor substrate 221 is led out of the case 211 through an opening formed on the back side of the case 211 with the bottom member 212 therebetween. The cable 251 led out from the case 211 is drawn out from between the pair of opening / closing mechanisms 302 and 303 toward the one end 212 </ b> A of the bottom member 212. The cable 251 pulled out to the one end 212A side of the bottom member 212 is directed to the image processing substrate 402 at the one end 212A of the bottom member 212. The cable 251 intersects (orthogonally) the horizontal X and Y directions. Direction: arrow Z direction). The cable 251 is drawn into the box 403 and the other end 251 </ b> B is connected to the image processing substrate 402.

  The copying machine 100 is formed by extending in the direction of arrow Z while facing the cable 251 from one end 212A of the bottom member 212, connected to the box 403, and grounded to the housing 411 (that is, formed of metal). E) A counter member 280 is provided.

  The facing member 280 electrically connects the bottom member 212 and the housing 411 and is disposed along the cable 251. The conductive opposing member 280 functions as a return current path for suppressing radiation noise from the cable 251 by being along the cable 251. The facing member 280 is formed in a flat plate shape. The opposing member 280 has one end connected to the bottom member 212 and the other end connected to the box 403, and is electrically connected to the housing 411 through the box 403.

  Furthermore, the copying machine 100 includes an extension member 290 provided in the vicinity of the opening / closing mechanism 302 so as to be electrically connected to the opening / closing mechanism 302 in FIG. 2, at least one of the pair of opening / closing mechanisms 302 and 303. . The extending member 290 is a plate-shaped conductive member (that is, formed of metal) formed in a rectangular shape. The extending member 290 is formed to extend vertically downward (arrow Z direction) so as to move away from the opening / closing mechanism 302. The extending member 290 is an open end in which a far end (lower end) on the side far from the opening / closing mechanism 302 in the arrow Z direction is opened. That is, the lower end of the extending member 290 in the arrow Z direction is not in contact with the bottom member 212 or the casing 411.

  The extending member 290 is formed to extend from one end 212A of the bottom member 212 in the arrow Z direction. The extending member 290 is formed of a member different from the bottom member 212, and a proximal end (upper end) on the side close to the opening / closing mechanism 302 in the arrow Z direction is fixed to one end 212 </ b> A of the bottom member 212 with a fixing member 291 such as a screw. It is fixed with. Thereby, the extending member 290 is electrically connected to the opening / closing mechanism 302.

  Thus, since the extending member 290 is fixed by the fixing member 291, for example, in the manufacturing process, after the image reading unit 201 is assembled to the image forming unit 401, the extending member 290 is moved to the bottom member 212. It is possible to attach. Accordingly, the extending member 290 does not get in the way during the operation of assembling the image reading unit 201 to the image forming unit 401. Further, when the image reading unit 201 is removed from the image forming unit 401 for maintenance or the like (when opened), the extending member 290 may be removed first. Accordingly, the extending member 290 does not get in the way when the image reading unit 201 is removed (opening operation).

  The extension member 290 has been described as being fixed to the bottom member 212 with a fixing member (fastener) 291 such as a screw. However, the fixing method is not limited to this, and the extension member 290 may be electrically connected. Any fixing method may be used. Further, the extending member 290 and the bottom member 212 may be integrally formed.

  FIG. 3 is a partial rear view of the copying machine 100 according to the first embodiment of the present invention. The opening / closing mechanism 302 includes a support body 312 having a rectangular parallelepiped shape, a fixed portion, and a swing portion that swings with respect to the fixed portion. The fixed portion is fixed to the support body 312, and the swing portion is a document feeder. A hinge mechanism 311 fixed to the unit 301. The opening / closing mechanism 302 includes a pair of flanges 313 that extend outward from the lower end of the support 312 in parallel with the arrow X direction, and the flanges 313 are fixed to the upper surface of the bottom member 212. Note that the flange 313 may be formed to extend inside the support body 312.

  The support 312 extends in the arrow Z direction at the portion facing the one end 212A side of the bottom member 212, and is opposed to the side (first side) 312A on the side close to the facing member 280 in the arrow X direction and the arrow X direction. The member 280 has a side (second side) 312B on the far side. Further, the extending member 290 extends in the arrow Z direction, the side (third side) 290C closer to the opposing member 280 in the arrow X direction, and the side (fourth side) farther from the opposing member 280 in the arrow X direction. ) 290D.

  The hinge mechanism 311 is supported on the upper surface of the support body 312. The hinge mechanism 311 viewed from the arrow Z direction is smaller or the same size as the support 312.

  As shown in FIG. 3, when viewed from the arrow Y direction, the center line extending in the arrow Z direction passing through the center of the opening / closing mechanism 302 in the arrow X direction extends in the arrow Z direction passing through the center of the support 312 in the arrow X direction. It is the central line. Hereinafter, the center line of the opening / closing mechanism 302 or the center line of the support 312 is referred to as a center line C1. Therefore, the center line C <b> 1 is also the center line of the entire opening / closing mechanism 302 and also the center line of the support body 312.

  The support body 312 and the flange 313 are integrally formed. For example, a single plate is bent into a convex shape. Therefore, the support 312 has a through hole in the arrow Y direction with the flange 313 fixed to the bottom member 212.

  The distance (first distance) in the arrow Z direction between the lower end 302A of the opening / closing mechanism 302 and the lower end (open end) 290B of the extending member 290 is L1. In addition, the distance (second distance) between an end 280A extending in the arrow Z direction on the opposite member 280 closer to the extending member 290 (opening / closing mechanism 302) and the center line C1 of the opening / closing mechanism 302 is L2. In the first embodiment, since the lower end 302A of the opening / closing mechanism 302 and the upper end 290A of the extending member 290 are at the same level (match) in the arrow Z direction, L1 is the same as the upper end 290A of the extending member 290. It is the length in the arrow Z direction with the lower end 290B. As shown in FIG. 3, the width in the arrow X direction of the support 312 is D1, and the width of the extending member 290 in the arrow X direction is D2.

  Here, a copying machine of a comparative example when the extending member 290 is not disposed will be described. FIG. 10 is a perspective view showing a copying machine of a comparative example. In the copying machine 100X of the comparative example shown in FIG. 10, the same components as those of the copying machine 100 of the first embodiment are denoted by the same reference numerals and description thereof is omitted. That is, the copying machine 100X omits the extending member 290 in the copying machine 100, and the other configuration is the same as that of the copying machine 100.

  Next, in order to facilitate understanding of the phenomenon in the first embodiment, resonance due to ESD when ESD is applied to the opening / closing mechanism 302 on the right side of the image reading unit 201 in the copying machine 100X of the comparative example shown in FIG. The phenomenon will be described. The resonance phenomenon when ESD is applied to the left opening / closing mechanism 302 of the image reading unit 201 is the same as the resonance phenomenon when ESD is applied to the right opening / closing mechanism 303, and thus the description thereof is omitted. .

  Since the ESD current includes a high-frequency component, it has a property of propagating not at the inside of the conductor but at the edge of the conductor. Therefore, the ESD applied to the point P of the opening / closing mechanism 302 on the right side of the image reading unit 201 mainly flows through the corner of the opening / closing mechanism 302 and propagates to the bottom member 212 where the opening / closing mechanism 302 is electrically connected. Since the opening / closing mechanism 302 is disposed at the end of the bottom member 212, the ESD current propagates through the rear side edge (one end 212A) of the bottom member 212 where the opening / closing mechanism 302 is disposed. Then, the ESD current branches into a horizontal edge and a vertical edge outside the facing member 280.

  The ESD current flowing through the edge in the horizontal direction of the facing member 280 flows through the edge on the back side of the bottom member 212 as it is. The ESD current that flows to the edge in the vertical direction of the facing member 280 flows to the box 403 of the image forming unit 401.

  Here, since the impedance of the connecting portion between the vertical edge of the facing member 280 and the end of the bottom member 212 is lower than that of the end of the bottom member 212, current is concentrated. On the other hand, since the corner of the opening / closing mechanism 302 in the vertical direction and the end of the bottom member 212 at the connecting portion of the bottom member 212 are open ends, the impedance is increased and the potential variation is increased. From these two phenomena, the connecting portion between the vertical edge of the opposing member 280 and the end of the bottom member 212 becomes an antinode of the current, and the central portion of the opening / closing mechanism 302 in the direction of the arrow X becomes a node of current. A resonance phenomenon occurs at a frequency where the distance L2 is ¼ wavelength. The current intensity distribution due to resonance is shown by a dotted line in FIG.

  Since the cable 251 is disposed at a position facing the opposing member 280 where the ESD current strongly flows due to the resonance phenomenon, the ESD current is electromagnetically coupled to the cable 251, and noise current due to ESD is induced in the cable 251, and the image signal Will be affected.

  On the other hand, in the copier 100 of the first embodiment, the ESD current applied to the point P of the right opening / closing mechanism 302 basically flows through a path substantially similar to that of the copier 100X of the comparative example.

  In FIG. 2, an extending member 290 having a length L1 is connected to one end 212A of the bottom member 212 in the vicinity of the lower end 302A of the opening / closing mechanism 302. Further, it is assumed that L1 = L2, and the extending member 290 is arranged so that the center line C1 of the opening / closing mechanism 302 (support body 312) and the center line C2 of the extending member 290 coincide. In FIG. 3, the extending member 290 is illustrated as being shifted from the center line C <b> 1 and the center line C <b> 2.

  As a result, the lower end 290B of the extending member 290 becomes a node of current where the potential fluctuation increases at a quarter wavelength of the resonance frequency, and the upper end 290A of the extending member 290 connected to the bottom member 212 is low at the resonance frequency. Impedance becomes an antinode of current. The current intensity distribution due to resonance is shown by a dotted line in FIG.

  Therefore, the noise current at the resonance frequency is confined in the upper end 290A of the extending member 290, is difficult to propagate along the peripheral edge (one end 212A) of the bottom member 212, and is generated in the section of the distance L2 of the one end 212A of the bottom member 212. Resonance is suppressed. Therefore, the current caused by resonance flowing in the facing member 280 is also reduced, and the propagation of ESD to the cable 251 disposed at the position facing the facing member 280 is also suppressed.

  As described above, according to the first embodiment, since the extending member 290 is connected to the bottom member 212, the ESD current due to resonance is confined in the extending member 290. Thereby, since the cable 251 and the path through which the ESD current flows can be separated from each other, induction of noise in the cable 251 due to electromagnetic coupling is suppressed, and deterioration of an image signal propagating through the cable 251 with a simple structure is suppressed. be able to.

  In order to confirm the above effects, the results of electromagnetic field simulation calculations for the shapes of the copying machine 100 of the first embodiment and the copying machine 100X of the comparative example will be described.

  The length L1 of the extending member 290 in the arrow Z direction is set to 130 [mm] which is the same as the distance L2. Further, the width D2 of the extending member 290 in the arrow X direction is set to 90 [mm], which is the same as the width D1 of the support body 312 of the opening / closing mechanism 302 in the arrow X direction. The extending member 290 is arranged so that the center line C1 of the support 312 and the center line C2 of the extending member 290 coincide with each other.

  The cable 251 is a flat cable, is not in contact with the opposing member 280, and the gap in the depth direction between the cable 251 and the opposing member 280 is 2 [mm].

  The cable 251 has three conductor lines, one in the middle as a signal line, and both adjacent signal lines as ground lines. The signal line was terminated on the image sensor substrate 221 with a resistance of 10 [Ω] assuming a driver IC, and terminated on the image processing substrate 402 with a resistance of 1 [MΩ] assuming a receiver IC. The ground line was connected to the ground of each substrate. The lowermost part of the image forming unit 401 is disposed at a position of 80 mm from the ground G. The ground G was a plain conductor.

  FIG. 4 is a graph showing a simulation result when ESD is applied to the copying machine 100 of the first embodiment and a simulation result when ESD is applied to the copying machine 100X of the comparative example. FIG. 4 shows a voltage calculation result of the termination resistance 1 [MΩ] on the image processing board 402 side when the initial charge value of ESD is 10 [KV] and ESD is applied to the point P of the right opening / closing mechanism 302. ing. In the graph shown in FIG. 4, the horizontal axis represents elapsed time and the vertical axis represents voltage value. For comparison, the calculation result in the copying machine 100X of the comparative example is also shown. From the calculation result, it can be seen that the copying machine 100 of the first embodiment can suppress the peak of the envelope of the induced voltage due to ESD more than the copying machine 100X of the comparative example.

  Next, a case where the extending member 290 is arranged so that the center line C1 of the opening / closing mechanism 302 and the center line C2 of the extending member 290 coincide with each other, and the distance L1 is changed while the distance L2 is constant will be described. .

  FIG. 5 is a graph showing a simulation result of voltage values received by the image processing board 402 when the length L1 of the extending member 290 is changed. The voltage value shown in FIG. 5 is an average value of the peak of the induced voltage caused by the ESD noise current generated in the termination resistor 1 [MΩ] on the image processing substrate 402 side. For comparison, the calculation results in the copying machine 100X of the comparative example are also shown. The distance L2 was 130 [mm].

  The following was found from the simulation results shown in FIG. The length of the extending member 290 is set so that the distance L1 is 0.70 times or more and 1.30 times or less with respect to the distance L2, that is, L1 / L2 is 0.70 or more and 1.30 or less. Thus, it was found that there was a noise reduction effect of 10% or more compared to the comparative example.

  Further, the length of the extending member 290 is set so that the distance L1 is 0.75 to 1.25 times the distance L2, that is, L1 / L2 is 0.75 to 1.25. By setting, it was found that there was a noise reduction effect of 20 [%] or more with respect to the comparative example.

  Furthermore, the length of the extending member 290 is set so that the distance L1 is 0.90 times or more and 1.20 times or less with respect to the distance L2, that is, L1 / L2 is 0.90 or more and 1.20 or less. By setting, it was found that there was a noise reduction effect of 30 [%] or more with respect to the comparative example.

  Next, the case where the length L1 of the extending member 290 is kept constant and the position of the extending member 290 in the arrow X direction is changed will be described.

  FIG. 6 is a diagram for explaining the simulation result of the voltage value received by the termination resistor of the image processing substrate 402 when the extending member 290 is offset in the arrow X direction (second direction) with respect to the support 312. FIG. FIG. 6A shows a voltage calculation result of the termination resistance 1 [MΩ] on the image processing substrate 402 side when the position of the extending member 290 is changed. For comparison, the calculation results in the copying machine 100X of the comparative example are also shown. FIG. 6B is a view for explaining the extending member 290 offset by each offset amount.

  Here, the width D1 of the support 312 of the opening / closing mechanism 302 is 90 [mm], and the width D2 of the extending member 290 is 30 [mm].

  From the calculation results, when the extending member 290 is arranged at a position where the center line C1 of the support 312 and the center line C2 of the extending member 290 coincide with each other in the direction of the arrow X, the most effective noise reduction effect is obtained. It was found that there was a reduction effect of 31 [%] relative to the comparative example. It has been found that when the extending member 290 is offset in the direction of the arrow X from there, the noise reduction effect becomes smaller as the offset amount increases.

  Specifically, when the extending member 290 is disposed at a position between a position offset by 75 [mm] to the left and a position offset by 60 [mm] to the right, the extension member 290 is 10 [%] or more with respect to the comparative example. It was found that there was a noise reduction effect. That is, when the extending member 290 is arranged in the direction of the arrow X, the side 290D is closer to the opposing member 280 than the side 312A by 15 [mm], and the side 290C is located at a position that coincides with the side 312B. It was found that there was a noise reduction effect of 10% or more compared to the comparative example.

  Further, when the extending member 290 is disposed at a position between the position offset by 30 [mm] to the left and the position offset by 45 [mm] to the right, the noise reduction is 20 [%] or more compared to the comparative example. I found it effective.

  Further, when the extending member 290 is arranged at a position where the center line C1 of the support 312 and the center line C2 of the extending member 290 coincide with each other in the direction of the arrow X, 30% with respect to the comparative example. It was found that the above noise reduction effect was obtained. Moreover, when the extending member 290 is arrange | positioned in the position between the position offset 15 [mm] to the right, it turned out that there exists a noise reduction effect of 30 [%] or more with respect to a comparative example.

  Next, a case where the width D2 of the extending member 290 is changed will be described. FIG. 7 is a graph showing a simulation result of voltage values received by the image processing board 402 when the width D2 of the extending member 290 is changed. FIG. 7 shows a voltage calculation result in the termination resistance 1 [MΩ] on the image processing substrate 402 side when the width D2 of the extending member 290 is changed. For comparison, the calculation results in the copying machine 100X of the comparative example are also shown. The width D1 of the support body 312 of the opening / closing mechanism 302 is set to 90 [mm], the extending member 290 is disposed at the center of the support body 312 of the opening / closing mechanism 302, and the width D2 is changed from 30 [mm] to 90 [mm]. I let you. In this case, it was found that there was no significant change in the noise reduction effect. From the above, it has been found that the width D2 of the extending member 290 has little influence on the noise reduction effect even if it is arbitrarily set within the range of one third or more of the width D1 and not more than the width D1. At this time, it is desirable that the extending member 290 is disposed at a position including the central portion of the opening / closing mechanism 302.

[Second Embodiment]
Next, an image forming apparatus according to a second embodiment of the present invention will be described. FIG. 8 is a perspective view of the copier when the copier as an example of the image forming apparatus according to the second embodiment of the present invention is viewed from the back side. Note that in the second embodiment, identical symbols are assigned to configurations similar to those in the first embodiment and descriptions thereof are omitted.

  The copying machine 100A includes an image forming unit 401A, an image reading unit 201 having a configuration similar to that of the first embodiment, a document feeding unit 301, and a pair of opening / closing mechanisms 302 and 303.

  The image forming unit 401A includes a housing 411A, an image forming unit 420 (see FIG. 1), a sheet feeding unit 430 (see FIG. 1), and an image processing substrate 402 as an image processing unit, as in the first embodiment. have.

  The image sensor substrate 221 and the image processing substrate 402 of the image reading unit 201 are electrically connected by a cable 251. The copying machine 100A includes a conductive box 403 in which an image processing board 402 is disposed and fixed to a side portion (specifically, a rear side portion) of the housing 411A. Further, the copying machine 100A includes an opposing member 280 that is connected to the box 403 and is electrically connected to the housing 411A via the box 403.

  In the second embodiment, the housing 411A includes a conductive top member 412 having one end 412A extending to one end 212A of the bottom member 212. The top member 412 is formed in a flat plate shape extending in the horizontal direction (arrow Y direction) so as to protrude rearward at the upper part of the housing 411A. The positions of the one end 212A of the bottom member 212 and the one end 412A of the top member 412 coincide with each other in the arrow Y direction.

  Between the one end 212A of the bottom member 212 and the one end 412A of the top member 412, a conductive member 295 such as a gasket that electrically connects the bottom member 212 and the top member 412 is disposed. The conductive member 295 is disposed immediately below the position where the opening / closing mechanism 302 is fixed on the bottom member 212.

  The extending member 290 is formed to extend from the vicinity of the conductive member at one end 412A of the top member 412 in the arrow Z direction that is the first direction.

  In the second embodiment, the extending member 290 is configured as a member separate from the top member 412, and a fixing member (fastening) such as a screw is provided near the opening / closing mechanism 302 (in the vicinity of the conductive member) at one end 412 </ b> A of the top member 412. G) It is fixed with 291. Specifically, the upper end of the extending member 290 in the arrow Z direction is an open end that is fixed to the one end 412A of the top member 412 by the fixing member 291 and the lower end of the extending member 290 in the arrow Z direction is opened. Therefore, the lower end of the extending member 290 in the arrow Z direction is not in contact with the housing 411A.

  Here, the distance L1 is a distance (first distance) in the arrow Z direction between the lower end of the opening / closing mechanism 302 and the lower end (open end) of the extending member 290. In the second embodiment, the distance L1 is the length of the extending member 290 in the arrow Z direction, the length of the conductive member in the arrow Z direction (thickness), and the length of the bottom member in the arrow Z direction (thickness). ).

  Note that the ratio L1 / L2 between the distance L1 and the distance (second distance) L2 and the offset range of the extending member 290 in the arrow X direction are the same as those in the first embodiment, and a description thereof is omitted.

  As described above, according to the second embodiment, as in the first embodiment, the bottom member 212 and the top member 412 are connected by the conductive member 295, and the extending member 290 is connected to the top member 412. Can be confined by the extending member 290. Thereby, since the cable 251 and the path through which the ESD current flows can be separated from each other, induction of noise in the cable 251 due to electromagnetic coupling is suppressed, and deterioration of an image signal propagating through the cable 251 with a simple structure is suppressed. be able to.

  Further, since the extending member 290 is arranged in the image forming unit 401A, it is possible to take measures even when it is difficult to add the extending member 290 to the image reading unit 201 due to problems such as assembling.

  The extension member 290 is described as being fixed to the top member 412 with a fixing member (fastener) 291 such as a screw. However, the fixing method is not limited to this, and the extension member 290 may be electrically connected. Any fixing method may be used. Further, the extending member 290 may be integrated with the top member 412 instead of a separate member.

  Moreover, although the case where the top member 412 and the bottom member 212 are connected by the conductive member 295 such as a gasket has been described, the connection method is not limited to this, and any connection is possible as long as it is electrically conductive. It may be a method. Further, the conductive member 295 may be omitted as long as at least electrical conduction between the one end 212A of the bottom member 212 and the one end 412A of the top member 412 is ensured.

[Third Embodiment]
Next, an image forming apparatus according to a third embodiment of the present invention will be described. FIG. 9 is a perspective view of the copier when the copier as an example of the image forming apparatus according to the third embodiment of the present invention is viewed from the back side. Note that in the third embodiment, identical symbols are assigned to configurations similar to those in the first and second embodiments and descriptions thereof are omitted.

  The copying machine 100B includes an image forming unit 401, an image reading unit 201, a document feeding unit 301, and a plurality of (for example, two) opening / closing mechanisms 302 and 303 having the same configuration as that of the first embodiment.

  Similar to the first embodiment, the image forming unit 401 includes a housing 411, an image forming unit 420 (see FIG. 1), a sheet feeding unit 430 (see FIG. 1), and an image processing substrate 402 as an image processing unit. Have. The image sensor substrate 221 and the image processing substrate 402 of the image reading unit 201 are electrically connected by a cable 251.

  The copying machine 100B includes a conductive box 403 in which an image processing substrate 402 is disposed and fixed to a side portion of the housing 411 (specifically, a side portion on the back side). The copier 100 </ b> B includes a counter member 280 that is connected to the box 403 and is electrically connected to the housing 411 through the box 403. The facing member 280 is disposed along the cable 251 and connected to the bottom member 212. Thereby, the opposing member 280 electrically connects the bottom member 212 and the housing 411. The conductive opposing member 280 functions as a return current path for suppressing radiation noise from the cable 251 by being along the cable 251.

  In the third embodiment, an extending member 290 electrically connected to one end 212A on the back side on the bottom member 212 at a position where the opening / closing mechanism 302 is fixed is provided. The extending member 290 is disposed so as to extend from the bottom member 212 in a vertically downward direction (arrow Z direction). The upper end of the extending member 290 is fixed so as to be electrically connected to the one end 212A of the bottom member 212.

  In the third embodiment, the copying machine 100 </ b> B includes a box 413 that is fixed to the housing 411 and contains a circuit board. The box 413 may be made of metal (conductive member) or resin.

  The extending member 290 is a member different from the box 413 and is formed as a rectangular flat plate, and also serves as a lid member for the box 413. An opening H is formed on a side surface of the box 413 (specifically, a surface in the rear side of the copying machine), and the extending member 290 is formed to extend to a position where the opening H of the box 413 is blocked. It is fixed to the box 413 by a fixing member (fastening member) 292 such as. The upper end of the extending member 290 is fixed to one end 212A of the bottom member 212 by a fixing member 291.

  Here, the distance L1 is a distance (first distance) in the arrow Z direction between the lower end of the opening / closing mechanism 302 and the lower end (open end) of the extending member 290. In the third embodiment, the distance L1 is the length of the extending member 290 in the arrow Z direction, as in the first embodiment.

  As described above, in the third embodiment, similarly to the first embodiment, the extending member 290 is connected to the bottom member 212, and resonance due to ESD is confined by the extending member 290. Thereby, since the cable 251 and the path through which the ESD current flows can be separated from each other, induction of noise in the cable 251 due to electromagnetic coupling is suppressed, and deterioration of an image signal propagating through the cable 251 with a simple structure is suppressed. be able to.

  Furthermore, since the extending member 290 also serves as a lid member for the box 413, the cost can be reduced by reducing the number of members and molds, and the assemblability can be improved.

  Even if the box 413 is formed of a conductive member, the lower end of the extending member 290 in the arrow Z direction acts as an open end against high-frequency noise, and as in the first embodiment, A current standing wave having the upper end of the extending member 290 as an antinode and a node at the lower end is generated. Therefore, as in the first embodiment, noise can be prevented from being induced in the cable 251.

  Moreover, although the extension member 290 demonstrated the case where it fixes to the bottom member 212 and the box 413 with fixing members (fasteners) 291 and 292, such as a screw, the fixing method is not limited to this, and is electrically Any fixing method may be used as long as it is conductive.

  The present invention is not limited to the embodiments described above, and many modifications are possible within the technical idea of the present invention.

  In the first to third embodiments, the case where the image forming apparatus is a copier has been described. However, the present invention is not limited to this. For example, the present invention may be applied to a facsimile, a copier and a multifunction machine of a facsimile, or the like. Is applicable.

  Moreover, although the 1st-3rd embodiment demonstrated the case where the extension member 290 was provided corresponding to the opening / closing mechanism 302 among the opening / closing mechanisms 302 and 303 provided in a pair, it is not limited to this. When the opening / closing mechanism 303 is formed of a conductive member such as metal, the extending member having the same configuration as the extending member 290 described in the first to third embodiments is provided for the opening / closing mechanism 303. May be provided.

DESCRIPTION OF SYMBOLS 100 ... Copy machine (image forming apparatus), 201 ... Image reading unit, 212 ... Bottom member, 212A ... One end, 214 ... Platen glass (original plate), 221 ... Image sensor substrate (image reading part), 251 ... Cable, 280 ... opposing member, 280A ... end side, 290 ... extending member, 290A ... upper end, 290B ... lower end (far end, open end), 301 ... document feeding unit (opening / closing member), 302 ... opening / closing mechanism, 302A ... lower end, 401 ... Image forming unit, 402 ... Image processing substrate (image processing unit), 411 ... Case, 420 ... Image forming unit

Claims (14)

An image reading unit having a conductive bottom member, a document table disposed above the bottom member, on which a document is placed, and an image reading unit that reads an image of the document placed on the document table; ,
An image processing unit that acquires an image signal and performs image processing, an image forming unit that forms an image on a sheet based on an image processing result by the image processing unit, and a conductive casing that houses the image forming unit An image forming unit having
An opening and closing member that is opened and closed with respect to the document table;
A pair of opening / closing mechanisms provided on the top surface of the bottom member so as to be along one end of the bottom member, wherein at least one of the pair is made of a conductive member;
The top surface of the bottom member is turned up and pulled out from between the pair of opening / closing mechanisms toward one end of the bottom member, and is bent in a first direction toward the image processing unit at one end of the bottom member. A cable connecting the reading unit and the image processing unit, and serving as a transmission line through which an image signal is transmitted from the image reading unit to the image processing unit;
A conductive opposing member formed extending in the first direction while facing the cable from one end of the bottom member, and grounded to the housing;
Provided in the vicinity of the at least one opening / closing mechanism so as to be electrically connected to the at least one opening / closing mechanism, and extending in the first direction so as to be away from the at least one opening / closing mechanism; A conductive extension member having an open end at a far end in the first direction with respect to the opening / closing mechanism,
The first distance in the first direction between the lower end of the at least one opening / closing mechanism and the open end of the extending member is an end side extending in the first direction on the side close to the extending member in the opposing member; Set to be 0.70 times or more and 1.30 times or less with respect to a second distance in a second direction orthogonal to the first direction with respect to a center line extending in the first direction of the at least one opening / closing mechanism. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the first distance is set to be 0.75 times or more and 1.25 times or less with respect to the second distance.   The image forming apparatus according to claim 1, wherein the first distance is set to 0.90 times or more and 1.20 times or less with respect to the second distance. The at least one opening / closing mechanism includes a hinge mechanism, a support body having a rectangular parallelepiped shape that supports the hinge mechanism, and a flange that is formed extending from a lower end of the support body and is fixed to an upper surface of the bottom member; Have
In the portion facing the one end side of the bottom member, the support body has a first side that extends in the first direction and is closer to the opposing member, and a second side that is far from the opposing member. ,
The extending member is formed in a rectangular shape and extends in the first direction, and has a third side near the opposing member and a fourth side far from the opposing member;
In the second direction, the extending member has a position where the fourth side is closer to the opposing member by 15 [mm] than the first side, and a position where the third side coincides with the second side. The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed at a position therebetween.   The extending member includes a position where the third side coincides with the first side in the second direction, and a position where the fourth side is 15 [mm] farther from the opposing member than the second side. The image forming apparatus according to claim 4, wherein the image forming apparatus is disposed at a position therebetween.   A position in which the extending member extends in the second direction, a center line extending in the first direction of the extending member coincides with a center line extending in the first direction of the support, and the third side 6. The image forming apparatus according to claim 4, wherein the image forming apparatus is disposed at a position between the support and a position that coincides with a center line extending in the first direction.   The extending member is disposed in a position where the center line extending in the first direction of the support and the center line extending in the first direction of the extending member coincide with each other in the second direction. The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein the extending member is formed to extend from one end of the bottom member in the first direction.   The image forming apparatus according to claim 8, wherein the extending member is configured by a member different from the bottom member, and is fixed to the bottom member by a fixing member. The housing has a conductive top member having one end extending to one end of the bottom member;
At least one end of the bottom member and one end of the top member are electrically connected,
The image forming apparatus according to claim 1, wherein the extending member is formed to extend from one end of the top member in the first direction.   The image forming apparatus according to claim 10, wherein the extending member is configured by a member different from the top member, and is fixed to the top member by a fixing member.   The conductive member that is disposed between at least one end of the bottom member and one end of the top member and electrically conducts the bottom member and the top member is provided. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the extending member is a lid member of a box fixed to the casing.   The image forming apparatus according to claim 1, wherein the opening / closing member is a document feeding unit that feeds a document to the document table.

Images