JP4717850B2 - Sheet body processing apparatus provided with ultrasonic sensor - Google Patents

Description

  The present invention relates to a sheet processing apparatus for performing predetermined processing in a processing unit on a sheet body (hereinafter referred to as “paper”) such as a document or paper transported via a transport path, and in particular, in the transport path. The present invention relates to a sheet processing apparatus including an ultrasonic sensor that detects multiple conveyance of a sheet.

  In an image forming apparatus and a sheet body processing apparatus such as an automatic document feeder applied to the image forming apparatus, a conveyance path is formed between a paper feeding unit that contains paper and a paper discharge unit through a processing unit. ing. A conveyance mechanism such as a conveyance roller or a conveyance belt is arranged in the conveyance path. In order to smoothly convey a sheet in the conveyance path and to properly process the sheet in the processing unit, it is necessary to convey a plurality of sheets so that they do not overlap in the conveyance path. If multiple sheets are transported with multiple sheets of paper, the processing conditions set in the processing unit will not be met and the processing state will deteriorate, and paper jams may occur in the transport path. Becomes higher.

  However, the characteristics of a plurality of sheets stored in the sheet feeding unit are likely to change according to environmental conditions such as humidity and temperature, and a plurality of sheets that are in close contact with each other are fed simultaneously from the sheet feeding unit. There is.

  Therefore, in the conventional sheet processing apparatus, a sensor for detecting the multiple conveyance state of the paper is arranged in the conveyance path. When the sensor detects the multiple conveyance of the sheet, the sheet processing apparatus stops the operations of the conveyance mechanism and the processing unit and prompts the user to remove the sheet from the conveyance path.

  As a sensor arranged in the conveyance path, there is one using an ultrasonic sensor (for example, see Patent Document 1). A transmitter and a receiver are arranged so as to face each other across the conveyance path, and an ultrasonic wave transmitted from the transmitter is received by the receiver. The amount of attenuation of the received signal when the sheet passes between the transmitter and the receiver is compared with a threshold value to detect multiple conveyance of the sheet.

  In a conventional sheet processing apparatus, a conveyance path is formed between a pair of guide plates that sandwich the front and back surfaces of a sheet, and the pair of guide plates are joined to each other. When the receiver and transmitter of the ultrasonic sensor are fixed to each of the pair of guide plates, vibration generated in the transmitter when transmitting ultrasonic waves propagates from one guide plate to the other guide plate and is transmitted to the receiver. The receiver erroneously detects the vibration propagated from a pair of guide plates as an ultrasonic wave that has passed through the paper, and even if paper multi-conveyance occurs, the received signal does not attenuate below the threshold, and multi-conveyance is accurately detected. Can not do it.

As a means for preventing the influence of vibration generated in the transmitter of the ultrasonic sensor on the received signal, a technique of providing a buffer material between the transmitter and the receiver is known (for example, see Patent Document 2 or 3). .)
Japanese Patent Laying-Open No. 2005-082350 Japanese Patent Application Laid-Open No. 07-159835 Japanese Utility Model Publication No. 01-156480

  However, if it is attempted to detect the multiple conveyance of the sheet by the ultrasonic sensor in the conveyance path of the sheet processing apparatus, it is necessary to attach the transmitter and the receiver with high positional accuracy. If the transmitter and the receiver are attached to the guide plate or the frame via a cushioning material such as rubber, the attachment position fluctuates and it becomes impossible to accurately detect the multiple conveyance of the paper.

  An object of the present invention is to devise the mounting state of the transmitter of the ultrasonic sensor with respect to the guide plate constituting the conveyance path, so that the receiver does not cause a false detection due to vibration generated in the transmitter when transmitting the ultrasonic wave. Another object of the present invention is to provide a sheet processing apparatus including an ultrasonic sensor capable of accurately detecting multiple conveyance of paper.

The sheet body processing apparatus provided with the ultrasonic sensor of the present invention includes first and second guide plates, an ultrasonic sensor, and a pedestal. The first and second guide plates are joined to each other at a portion through which the recording medium does not pass, and are disposed with a gap serving as a paper conveyance path between the thickness directions of the first and second guide plates. The ultrasonic sensor includes a transmitter and a receiver that are arranged to face each other across the conveyance path. The pedestal is attached to the first guide plate with the transmitter attached, and at least a part thereof is made of a resin material. The sheet body processing apparatus forms an image on the sheet conveyed in the conveyance path by the image forming unit, and detects multiple conveyance of the sheet in the conveyance path based on the reception signal of the receiver.

  In this configuration, the transmitter is attached to the first guide member via the pedestal. The pedestal is at least partially made of a resin material. Even when the first and second guide plates are joined to each other, a part of the vibration propagation path from the transmitter to the base, the first and second guide plates to the receiver is made of a resin material. There is a part that has been. The vibration generated by the transmitter is alleviated by the resin material, and the vibration is not transmitted to the receiver attached to the second guide plate in a state that affects the received signal.

  The pedestal may include a fixing member made of a resin material. The fixing member fixes the transmitter in a direction along the output direction of the ultrasonic wave on the side opposite to the ultrasonic wave output side from the transmitter. Even when the transmitter generates vibration in the direction along the output direction of the ultrasonic wave, this vibration is alleviated by the fixed member, and the vibration generated by the transmitter affects the received signal at the receiver attached to the second guide plate. Can be prevented from being transmitted.

  The pedestal may fix the transmitter in a state where movement in a plane orthogonal to the output direction of the ultrasonic wave from the transmitter is restricted. The vibration in the direction along the output direction of the ultrasonic wave generated in the transmitter is mitigated by the fixing member, and the vibration generated by the transmitter is transmitted to the receiver attached to the second guide plate in a state that affects the received signal. Can be prevented.

  The first and second guide plates may be made of a metal material, and a portion of the pedestal excluding at least a part may be made of a metal material. Even if the vibration generated by the transmitter is easily transmitted from the pedestal to the receiver via the first and second guide plates, the vibration generated in the transmitter is mitigated by the fixing member, and the second guide plate It is possible to prevent transmission to the attached receiver in a state that affects the received signal.

  The resin material may be a material having a flexural modulus of 700 MPa to 7000 MPa. The vibration in the direction along the output direction of the ultrasonic wave generated in the transmitter is mitigated by the fixing member, and the vibration generated by the transmitter is transmitted to the receiver attached to the second guide plate in a state that affects the received signal. Can be prevented.

  According to this invention, the vibration generated by the transmitter is mitigated by the resin material existing in a part of the propagation path of the vibration from the transmitter to the receiver via the base and the first and second guide plates. be able to. It is possible to prevent vibrations from being transmitted to the receiver attached to the second guide plate in a state that affects the received signal. The receiver does not cause erroneous detection due to vibration generated in the transmitter when transmitting an ultrasonic wave, and multiple conveyance of paper can be accurately detected.

  Hereinafter, a sheet processing apparatus including an ultrasonic sensor according to the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus which is a sheet processing apparatus including an ultrasonic sensor according to an embodiment of the present invention. The image forming apparatus 100 forms a monochrome image on a predetermined sheet (sheet body) in accordance with image data obtained by scanning a document or image data transmitted from the outside.

  The image forming apparatus 100 includes an ADF (Auto Document Feeder) 1, an image reading unit 2, an optical writing unit 3, a developing device 4, a photoconductor 5, a charger 6, a cleaner unit 7, a transfer belt 8, a fixing unit 9, and paper feeding. A unit 400 and the like are provided.

  The ADF 1 includes a document tray 27, a document transport path S1, a paper discharge tray 36, and the like, and transports a document from which image data is to be read to a document reading position A. The document tray 27 places a bundle of documents. The document transport path S1 transports a document placed on the document tray 27 to the paper discharge tray 36 via the document reading position A. Details will be described later.

  The image reading unit 2 includes a light source holder 13, a mirror group 14, a CCD 15, and the like. When scanning the reading surface of the document conveyed from the document tray 27 to the document reading position A, the light source holder 13 and the mirror group 14 are stopped at predetermined positions.

  The light source holder 13 irradiates light on the reading surface of the document conveyed from the document tray 27 to the document reading position A. The light reflected by the reading surface is optically path-converted through the mirror group 14, imaged on the CCD 15, and converted into electronic image data.

  The charger 6 uniformly charges the surface of the photoconductor 5 to a predetermined potential. In the image forming apparatus 100 of the present embodiment, the charger type charger 6 is used, but a contact type roller type or brush type charger can also be used.

  The optical writing unit 3 employs a two-beam method including two laser irradiation units 16A and 16B in order to cope with high-speed printing processing, and exposes the surface of the photoconductor 5 based on input image data. To form an electrostatic latent image. The laser irradiation units 16A and 16B irradiate laser light based on the image data. The mirror groups 17A and 17B reflect the irradiated laser light and guide it to the uniformly charged surface of the photoconductor 5.

The developing device 4 is disposed in the vicinity of the surface of the photoreceptor 5 and visualizes the electrostatic latent image formed on the surface of the photoreceptor 5 with toner. The transfer belt 8 is stretched in a loop between a plurality of rollers below the photoreceptor 5, and has a resistance value of about 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm. Inside the loop-shaped movement path of the transfer belt 8, a transfer roller 22 that presses against the photoconductor 5 with the transfer belt 8 interposed therebetween is provided. A predetermined transfer voltage is applied to the transfer roller 22, and the toner image carried by the photoconductor 5 is transferred to a sheet passing through a transfer position between the transfer belt 8 and the photoconductor 5.

  The cleaner unit 7 removes and collects the toner remaining on the surface of the photoconductor 5 after the toner image is transferred to the paper.

  The fixing device 9 includes a heating roller 23 and a pressure roller 24. The heating roller 23 is heated to a temperature at which the toner can be melted by an internal heater. The pressure roller 24 is pressed against the peripheral surface of the heating roller 23 with a predetermined pressure. The fixing device 9 firmly fixes the toner image on the paper by heating and pressurizing the recording paper passing between the heating roller 23 and the pressure roller 24. The sheet that has passed through the fixing device 9 is discharged to a discharge tray 12 mounted on one side surface of the image forming apparatus 100.

  The paper feed unit 400 includes paper feed cassettes 401, 402, 403, 404, a manual feed tray 405, and the like. Each of the paper feed cassettes 401, 402, 403, 404 stores a plurality of sheets of the same size. On the manual feed tray 405, paper of a size or quality that is not frequently used is placed.

  The paper feed unit 400 feeds paper one by one from one of the paper feed cassettes 401, 402, 403, 404 and the manual feed tray 405. The sheet fed from the sheet feeding unit 400 is transported to the transfer position between the photoreceptor 5 and the transfer belt 8 via the transport path 10 and the transport path 11. Thereafter, the toner image is transferred and fixed on the sheet as described above, and is discharged to the discharge tray 12.

  FIG. 2 is a cross-sectional view illustrating a schematic configuration of an ADF that is a sheet processing apparatus including an ultrasonic sensor according to an embodiment of the present invention. The ADF 1 includes a document tray 27, a pickup roller 28, a paper feed roller 30 and a separating roller 29, a driving roller 32 and a pressing roller 31, a registration roller 33, a paper discharge roller 35, and a paper discharge tray 36.

  The pickup roller 28 sends out the uppermost document in the document bundle placed on the document tray 27 to the document conveyance path 213. The paper feed roller 30 and the separating roller 29 convey the documents sent to the document conveyance path 213 to the downstream side of the document conveyance path 213 while separating the documents one by one.

  The driving roller 32 and the pressing roller 31 convey the document along the document conveyance path 213. The pressing roller 31 is a driven roller that presses the document against the driving roller 32. The registration roller 33 is disposed on the downstream side of the driving roller 32 and the pressing roller 31 in the direction of the arrow F1 that is the document conveyance direction. The registration roller 33 sends out the document so that the document passes through the document reading position A on the document table 34 at a predetermined timing. The rotation axis of the registration roller 33 is arranged in a direction orthogonal to the arrow F1 direction. The paper discharge roller 35 discharges the document whose image has been read to the paper discharge tray 36.

  The document tray 27 can move in the vertical direction, and when a bundle of documents is placed, a sensor (not shown) detects it. When a printing request is made by the user, the document tray 27 moves upward so that the recording paper comes into contact with the pickup roller 28.

  The document is conveyed by the driving roller 32 and the pressing roller 31, and the front end is abutted against the resist roller 33 in a stopped state. Thereby, when the document is skewed, the skew of the document is corrected. As described above, the registration roller 33 starts rotating at a timing when the document is sent onto the document table 34 at a predetermined timing.

  In addition, the ADF 1 includes a double feed detection sensor 37 in the vicinity of the driving roller 32 and the pressing roller 31 disposed on the downstream side in the direction of the arrow F 1 with respect to the paper feeding roller 30 and the separating roller 29. The double feed detection sensor 37 is an ultrasonic sensor, and includes a wave transmitter 38 and a wave receiver 39 as shown in FIG. 3, and when the document D is overlapped and conveyed to the document conveyance path S1, the document D is detected. Detect double feed. The wave transmitter 38 corresponds to the transmitting unit of the present invention, and the wave receiver 39 corresponds to the receiving unit of the present invention.

  The multi-feed detection sensor 37 is usually provided even when the originals D are overlapped and sent to the original transport path S1. This is because the document D is conveyed at a high speed so as to correspond to the above, and there is a possibility that multiple conveyance occurs even if the separation roller 29 is provided.

  The ultrasonic sensor is hardly affected by the thickness, color, etc. of the recording paper as compared with the optical sensor and has few false detections.

  As shown in FIG. 6, the wave transmitter 38 faces the wave receiver 39 across the document conveyance path S <b> 1 so as to be inclined with respect to the arrow F <b> 2 direction which is a direction orthogonal to the arrow F <b> 1 direction. The transmitter 38 outputs an ultrasonic wave in one direction toward the receiver 39. 6 is an enlarged cross-sectional view showing a mounting state of the first pedestal 41, the second pedestal 42, and the double feed detection sensor 37 as seen from the direction of the arrow Y shown in FIG.

  The wave receiver 39 is located on the output direction of the ultrasonic wave output from the wave transmitter 38, receives the ultrasonic wave, and converts it into electrical energy. As in the present embodiment, the arrangement positions of the transmitter 38 and the receiver 39 are inclined with respect to the direction of the arrow F2, so that the output direction of the ultrasonic waves is not orthogonal to the surface direction of the document D. It is for doing so. In other words, when the output direction of the ultrasonic wave is orthogonal to the surface direction of the document D, the ultrasonic wave reflected from the document D is reflected on the upper surface of the document transport path S1 and reaches the wave receiver 39, and erroneous detection occurs. Because it will do.

  As shown in FIG. 3, the drive roller 32 and the pressing roller 31 carry out the conveyed document D at a predetermined carry-out angle so as to press the document D down the document conveyance path S1. For this reason, the drive roller 32 is disposed downstream of the pressing roller 31 in the direction of the arrow F1.

  The double feed detection sensor 37 is an area in which the document D is conveyed along the document conveyance path S1 while being in contact with the bottom surface of the document conveyance path S1, specifically, the document D unloaded from the driving roller 32 and the pressing roller 31. Double feed of the document D is detected in the vicinity of a contact point C between the leading edge and the bottom surface of the document transport path S1.

  The ultrasonic wave transmitted from the transmitter 38 is attenuated when passing through the document D. Here, when one document D passes between the transmitter 38 and the receiver 39, and when the two documents DA and DB overlap each other as shown in FIG. As shown in FIG. 5, the attenuation amount of the ultrasonic wave received by the receiver 39 is different from the case of passing between the receiver 39 and the receiver 39. This is because the ultrasonic wave transmitted from the transmitter 38 is greatly attenuated by a slight air layer where the originals DA and DB overlap.

  A control unit (not shown) provided in the image forming apparatus 100 compares the level of the electric energy converted by the receiver 39 shown in FIG. 5 with a predetermined threshold value, so that the document D is normally processed. It is determined whether the sheets are being conveyed one by one or in a multiple conveyance state. The control unit controls the operation of the entire image forming apparatus. FIG. 5 is an explanatory diagram showing the relationship between the number of documents to be fed and the electrical energy of ultrasonic waves received by the wave receiver 39.

  As shown in FIG. 6, the transmitter 38 is fixed by screws 61 in a state of being fitted into the opening 41 </ b> A of the first base 41. Further, the wave receiver 39 is fixed by screws 62 in a state of being fitted into the opening 42A of the second pedestal 42 as shown in FIG. The transmitter 38 and the receiver 39 are positioned by the opening 41A and the opening 42A. The positions of the transmitter 38 and the receiver 39 positioned by the opening 41A and the opening 42A correspond to the first predetermined position and the second predetermined position of the present invention.

  The first pedestal 41 is fixed to the outer wall upper surface 60A (corresponding to the first guide plate of the present invention) of the document transport path S1 with two screws 65 and 66. The through holes 75 and 76 of the first pedestal 41 that pass through the screwed portions of the screws 65 and 66 are long holes in which grooves are formed along the direction of the arrow F2. Therefore, it is possible to adjust the position of the first pedestal along the arrow F2 direction. The screws 65 and 66 and the through holes 75 and 76 correspond to the position adjusting means of the present invention.

  The second pedestal 42 is fixed to the outer wall bottom surface 60B (corresponding to the second guide plate of the present invention) of the document transport path S1 with two screws 67 and 68. The through holes 77 and 78 of the second pedestal 42 that pass through the screwed portions of the screws 67 and 68 have a diameter that allows the screwed portions to pass therethrough. Therefore, the position of the second pedestal 42 cannot be adjusted along the arrow F2 direction, and the second pedestal 42 is fixed at one point by screws 67 and 68.

  FIG. 7 is an explanatory diagram showing a procedure of a sensor mounting method for mounting the first pedestal 41, the second pedestal 42, and the double feed detection sensor 37 using the pedestal position adjusting jig. When attaching the double feed detection sensor 37 in a production process or the like, the operator first fixes the second pedestal 42 using screws 67 and 68 and opens the second positioning member 82 in the opening 42A as shown in FIG. Through the document transport path S1 (member mounting step).

As for the 2nd positioning member 82, the shape of fitting part 82A fitted to opening 42A is the same shape as wave receiver 39, and cylindrical extension part 82B has extended from fitting part 82A. In the extending portion 82B, the shaft extends in the output direction of the ultrasonic wave output from the transmitter 38 in a state where the second positioning member 82 is inserted into the opening 42A. The second positioning member 82 is positioned by the opening 42A. Further, the fitting portion 82A is formed with a protruding portion 82C that fits into a screwing hole into which the screw 62 is screwed. The second positioning member 82 is fixed to the second pedestal 42 by fitting the protruding portion 82C into the screw hole.
Note that the attachment of the second pedestal 42 and the attachment of the second positioning member 82 may be either first or simultaneously.

  Next, the first pedestal 41 is temporarily fixed with screws 65 and 66. Thereafter, as shown in FIG. 7B, the first positioning member 81 is inserted into the opening 41A toward the inside of the document conveyance path S1. At this time, the through-hole 81C formed in the first positioning member 81 is externally fitted to the extending portion 82B of the second positioning member (pedestal positioning step). At this time, the through hole 81C is externally fitted to the extending portion 82B in the output direction of the ultrasonic wave output from the wave transmitter 38. Thereby, the one end side of the extension part 82B penetrates. The first pedestal 41 may not be temporarily fixed. The output direction of the ultrasonic wave corresponds to the predetermined direction of the present invention.

  In the first positioning member 81, the shape of the fitting part 81A fitted to the opening 41A is the same as that of the wave transmitter 38, and a cylindrical extending part 81B extends from the fitting part 81A. The first positioning member 81 is positioned by the opening 41A. Further, the first positioning member 81 is fixed by being externally fitted to the second positioning member 82.

  As described above, the positions of the first pedestal 41 and the second pedestal 42 are determined in a state where the first positioning member 81 and the second positioning member 82 are fitted in the output direction of the ultrasonic wave. Thereafter, in this state, the first pedestal 41 is moved and adjusted along the direction of the arrow F2 and fixed using the screws 65 and 66 (pedestal fixing step). In addition, the 1st positioning member 81 and the 2nd positioning member 82 comprise the base position adjustment jig of this invention.

  Next, the first positioning member 81 and the second positioning member 82 are removed, and instead the transmitter 38 and the receiver 39 are attached as shown in FIG. 6 (attachment step). Thereby, the positional accuracy of the transmitter 38 and the receiver 39 attached by removing the first positioning member 81 and the second positioning member 82 can be ensured.

  Further, the first positioning member 81 and the second positioning member 82 are positioned using the opening 41A as the first positioning means for positioning the transmitter 38 and the receiver 39 and the opening 42A as the second positioning means. Therefore, it is not necessary to form a new positioning hole, and it is possible to prevent the first pedestal 41 and the second pedestal 42 from increasing in size only for positioning. Therefore, it is possible to reduce the space required only for positioning while ensuring the positional accuracy of the transmitter 38 and the receiver 39 (the first pedestal 81 and the second pedestal 82).

  In the present embodiment, the first positioning member 81 is provided with a through hole 81C, and the first positioning member 81 is externally fitted to the second positioning member 82 from above, so that the operator looks into the through hole 81C from above. The external fitting operation can be performed while visually recognizing the position of the second positioning member 82. Therefore, the first positioning member 81 can be easily fitted on the second positioning member 82 from above, and the workability of attaching the first base 41 and the second base 42 can be improved.

  In the present embodiment, a plurality of grooves 82D are formed on one end side of the extending portion 82B of the second positioning member 82 by providing a partition wall. The groove 82D has a groove direction parallel to a direction orthogonal to the extending direction of the extending part 82B, and is used as an index representing the protruding amount of the extending part 82B. By this index, the operator can visually check the distance between the first pedestal 41 and the second pedestal 42 in a state where the first positioning member 81 and the second positioning member 82 are fitted. One end side of the fitting portion 81A corresponds to the penetrating portion of the present invention. In addition, the index is not limited to the groove 82D, and any index can be used as long as the distance between the first pedestal 41 and the second pedestal 42 such as a scale can be visually observed.

  In addition, the structure which does not protrude the 1st positioning member 81 at the one end side of the extension part 82B may be sufficient. For example, as shown in FIG. 8, a first positioning member 81 having a fitting hole 91 and a peep hole 92 may be used. The fitting hole 91 is externally fitted to the extending portion 82B. The peep hole 92 communicates with the fitting hole 91 on one end side, and the other end side is exposed to the outside on the fitting portion 81A side.

  Therefore, the operator can perform work while confirming the position of the extending portion 82B from the peep hole 92. Moreover, since the peeping hole 92 is smaller than the diameter of the extension part 82B, it has a function of a stopper that restricts the extension part 82B from being fitted into the fitting hole 91 too much. Therefore, the distance between the first pedestal 41 and the second pedestal 42 can always be kept constant. Moreover, as shown in FIG. 9, the structure without the peep hole 92 may be sufficient.

  In this embodiment, since only the first pedestal 41 can be adjusted in position along the direction of the arrow F2, there is no need to adjust the positions of the two pedestals while adjusting the pedestal. Can be improved. In addition, since the first pedestal 41 that can be adjusted in position is disposed above the second pedestal 42, it is easy for the operator to adjust the position of the first pedestal 41, and the workability of mounting the pedestal is improved. Can be made.

  In this embodiment, the wave transmitter 38 is fixed to the first pedestal 41 and the wave receiver 39 is fixed to the second pedestal 42, but the reverse may be possible. Further, the direction of position adjustment of the first pedestal 41 is the arrow F2 direction, but it is not particularly limited to this, and the direction in which the output direction of the ultrasonic wave is inclined with respect to the surface direction of the document being conveyed. If it is.

  Further, in the present embodiment, as shown in FIG. 1, a double feed detection sensor 137 having the same configuration as the double feed detection sensor 37 is disposed on the paper transport path 11 on the original transport path S1, and the paper on which an image is formed. Prevents double feed. The double feed detection sensor 137 is an ultrasonic sensor, and includes a wave transmitter 138 and a wave receiver 139, and detects multiple conveyance of sheets conveyed in the conveyance path 11 with a plurality of sheets overlapped. The transmitter 138 corresponds to the transmitter of the present invention, and the receiver 139 corresponds to the receiver of the present invention.

  FIG. 8 is a perspective view of a main part of a sheet conveyance path formed in the image forming apparatus. In the paper transport path 11 (corresponding to the transport path of the present invention), the wave transmitter 38 is fitted into the first pedestal 141 and fixed by the pressing plate 143 (corresponding to the fixing member of the present invention). The holding plate 143 is fixed by screws 161. The pressing plate 143 is a resin molded product, and materials such as polycarbonate (PC), polypropylene (PP), and ABS can be used. The bending elastic modulus of these materials is 700 MPa to 7000 MPa. The thickness of the pressing plate is 1 mm.

  FIG. 9 is a perspective view of the main part of the paper transport path viewed from another viewpoint. FIG. 10 is a perspective view showing positions of the transmitter, the pressing plate, and the opening in a state where the first pedestal is removed. The ultrasonic waves in the transmitter 138 are transmitted toward the opening 144. The holding plate 143 fixes the transmitter 138 on the back surface with respect to the transmission direction of the ultrasonic waves.

FIGS. 11A to 11D are diagrams illustrating experimental results of the double feed detection sensor. 11A to 11D are diagrams in which the vertical axis represents the output value of the reception signal of the receiver 139 and the horizontal axis represents time. In the “comparative example” shown in FIG. 11A, the pressing plate 143 is made of metal (material: iron, thickness: 1 mm). When a 52 g / m ² sheet is conveyed in a double feed state, the output of the received signal may exceed the threshold, and the double feed state cannot be detected.

In the “Example” shown in FIG. 11B, the pressing plate is made of resin (material: polycarbonate, thickness: 1 mm). As in the comparative example, when a 52 g / m ² sheet is conveyed in a double feed state, the output of the received signal is sufficiently lower than the threshold value, and the multiple conveyance state can be accurately detected.

In the “example” shown in FIG. 11C, the pressing plate is made of resin (material: polypropylene, thickness: 1 mm). As in the comparative example, when a 52 g / m ² sheet is conveyed in a double feed state, the output of the received signal is sufficiently lower than the threshold value, and the multiple conveyance state can be accurately detected.

In the “example” shown in FIG. 11D, the pressing plate is made of resin (material: ABS, thickness: 1 mm). As in the comparative example, when a 52 g / m ² sheet is conveyed in a double feed state, the output of the received signal is sufficiently lower than the threshold value, and the multiple conveyance state can be accurately detected.

  As shown in FIG. 12A, an upper guide plate (corresponding to a first guide plate of the present invention) 160A and a lower guide plate (corresponding to the second guide plate of the present invention) constituting the paper transport path 11. 160B is made of a metal material as a raw material, and is joined to each other at both ends in a direction orthogonal to the paper transport direction.

  For this reason, in the comparative example using the metal holding plate 143, the vibration generated in the transmitter 138 passes through the first pedestal 141, the upper guide plate 160 </ b> A, the lower guide plate 160 </ b> B, and the second pedestal 142. Propagate to the receiver 139.

  On the other hand, in the embodiment using the resin pressing plate 143, in particular, the vibration in the direction along the output direction of the ultrasonic waves generated on the back surface of the transmitter 138 is mitigated by the pressing plate 143, and the received signal It is considered that the vibration that affects the output of the signal did not propagate to the receiver 139.

  As shown in FIG. 12B, the inner diameter of a part of the opening 141A of the transmitter 138 in the first pedestal 141 is formed larger than the outer diameter of the transmitter 138, and the presser plate 143 is opened. 141 may be formed so that a part thereof is inserted between the inner peripheral surface of 141 and the outer peripheral surface of the transmitter 138. Thereby, in-plane vibration perpendicular to the output direction of the ultrasonic wave generated in the transmitter 138 can be reduced.

  As shown in FIG. 12C, an insertion member 141A made of a resin material may be disposed between the first pedestal 141 and the upper guide plate 160A. The vibration generated in the transmitter 138 is prevented from propagating from the first pedestal 141 to the upper guide plate 160A, and as a result, the vibration that affects the output of the received signal is prevented from propagating to the receiver 139. be able to.

  Further, the entire first pedestal 141 can be made of a resin material. By constituting at least a part of the parts constituting the first pedestal 141 with a resin material, the resin material is arranged in a part of the propagation path to the wave receiver 139 of the vibration generated in the wave transmitter 138, and the wave is transmitted. It suffices to reduce the vibration generated in the receiver 138 so that the vibration that affects the output of the received signal does not propagate to the receiver 139.

  The configuration of the double feed detection sensor 137 can be similarly implemented in the double feed detection sensor 37.

  Further, the positional relationship between the openings 141A and 142A is maintained with high accuracy by the positioning method shown in FIG. Since the position of the transmitter 138 can be maintained with high accuracy by the opening 141A, the fixing position of the transmitter 138 can be fixed by the holding plate 143 without fluctuation, and the positional accuracy is improved and erroneous detection is performed. It is possible to achieve both of prevention.

  Finally, the description of the above-described embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. Furthermore, in the present embodiment, the image forming apparatus and the ADF have been described. However, the present invention can be applied to any sheet body processing apparatus including an ultrasonic sensor. For example, there is a paper feeding device that conveys a recording paper to a predetermined position.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus as a sheet body processing apparatus including an ultrasonic sensor according to an embodiment of the present invention. It is sectional drawing which shows the structure of the outline of ADF as the sheet | seat body processing apparatus. It is sectional drawing to which a part of same ADF was expanded. It is sectional drawing to which a part of same ADF was expanded. It is explanatory drawing which shows the relationship between the double feed number of a document, and the electrical energy of the ultrasonic wave which the receiver received. It is an expanded sectional view which shows the attachment state of the base and double feed detection sensor seen from the arrow Y direction of FIG. (A) And (B) is explanatory drawing which shows the procedure of the sensor attachment method which attaches a 1st base, a 2nd base, and a double feed detection sensor using a base position adjustment jig. FIG. 3 is a perspective view of a main part of a paper conveyance path formed in the image forming apparatus. It is a perspective view of the principal part of the paper conveyance path seen from another viewpoint. FIG. 6 is a perspective view showing positions of a transmitter, a pressing plate, and an opening in a state where a first pedestal is removed. (A)-(D) are figures which show the experimental result of a double feed detection sensor. (A) is a cross-sectional view of the main part of the paper transport path, (B) is a cross-sectional view of the main part of the paper transport path of an image forming apparatus according to another embodiment of the present invention, (C) is this FIG. 10 is a cross-sectional view of a main part of a sheet conveyance path of an image forming apparatus according to still another embodiment of the invention.

Explanation of symbols

11-paper transport path (transport path)
37,137-Double feed detection sensor (ultrasonic sensor)
38,138-Transmitter (transmitter)
39,139-receiver (receiver)
41,141-first pedestal 41A, 141A-opening 42,142-second pedestal 42A, 142A-opening 160A-upper guide plate (first guide plate)
160B-lower guide plate (second guide plate)

Claims (5)

A first guide plate and a second guide plate provided with a gap serving as a conveyance path for the sheet body between the thickness directions of each other;
An ultrasonic sensor including a transmitter and a receiver arranged to face each other across the conveyance path;
A pedestal attached to the first guide plate in a state in which the transmitter is attached, and a pedestal at least partially made of a resin material,
The first and second guide plates are joined to each other at a portion through which the recording medium does not pass,
A sheet processing apparatus including an ultrasonic sensor that detects multiple conveyance of a sheet in the conveyance path based on a reception signal of the receiver. The pedestal includes a fixing member that fixes the transmitter in a direction along an ultrasonic output direction on a side opposite to an ultrasonic output side from the transmitter, and the fixing member is made of a resin material. Item 12. A sheet processing apparatus comprising the ultrasonic sensor according to Item 1 . The sheet processing with the ultrasonic sensor according to claim 1 or 2 , wherein the pedestal fixes the transmitter in a state where movement in a plane orthogonal to an output direction of the ultrasonic wave from the transmitter is restricted. apparatus. The ultrasonic sensor according to any one of claims 1 to 3 , wherein the first and second guide plates are made of a metal material, and a portion excluding the at least part of the pedestal is made of a metal material. Sheet body processing apparatus. The sheet processing apparatus provided with the ultrasonic sensor according to any one of claims 1 to 4 , wherein the resin material is a material having a flexural modulus of 700 MPa to 7000 MPa.

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