Ultrasonic devices, double feed detection devices, transport devices, and scanners

Abstract

To provide an ultrasonic device that is resistant to the adhesion of foreign matter to the ultrasonic transmitting and receiving surfaces and capable of transmitting ultrasonic waves at high sound pressure or receiving ultrasonic waves with high sensitivity; a double-feed detection device equipped with such an ultrasonic device and capable of detecting double-feeds with high accuracy; a transport device equipped with such a double-feed detection device; and a scanner equipped with such a transport device. [Solution] An ultrasonic device comprising an ultrasonic element having an ultrasonic transmitting and receiving surface for performing at least one of ultrasonic transmission and ultrasonic reception, and a housing for housing the ultrasonic element, wherein the housing has a reflective surface for reflecting the ultrasonic, a waveguide for propagating the ultrasonic, and an opening provided at one end of the waveguide through which the ultrasonic passes, and the length of the waveguide is longer than the width of the waveguide.

Description

Technical Field

[0001] The present invention relates to an ultrasonic device, a double-feed detection device, a conveying device, and a scanner.

Background Art

[0002] Patent Document 1 discloses an ultrasonic device that detects double feeding of sheets using an ultrasonic device. This ultrasonic device includes a pair of ultrasonic devices arranged across a sheet conveyance path. Ultrasonic waves are transmitted from one ultrasonic device, and the ultrasonic waves transmitted through the sheet are received by the other ultrasonic device. As a result, based on the intensity of the received signal of the ultrasonic waves, a sheet conveyance device for a scanner capable of detecting that a plurality of sheets are fed simultaneously can be realized.

[0003] Further, Patent Document 1 discloses that an ultrasonic device is arranged inside a shield portion having an opening, and a mesh-like protection member for suppressing intrusion of foreign matter is provided at the opening through which ultrasonic waves pass.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is room for improvement in the ultrasonic device of Patent Document 1. Specifically, when the mesh has a coarse mesh size, foreign matters such as paper dust that have passed through the protection member adhere to the surface of the ultrasonic device, resulting in a problem that the transmission and reception sensitivity of ultrasonic waves decreases. Further, when the mesh size is made finer, when cleaning the foreign matter adhering to the surface of the protection member with a cleaning liquid, the moisture of the cleaning liquid and the paper dust mix and tend to adhere to the protection member, resulting in a problem that the transmission and reception sensitivity of ultrasonic waves decreases.

[0006] Therefore, there is a need for an ultrasonic device that is resistant to the adhesion of foreign matter to the ultrasonic transmitting and receiving surfaces, and that can transmit ultrasonic waves with high sound pressure or receive ultrasonic waves with high sensitivity. [Means for solving the problem]

[0007] An ultrasonic device according to an application example of the present invention is, An ultrasonic element having an ultrasonic transmitting and receiving surface that performs at least one of ultrasonic transmission and ultrasonic reception, A housing for the ultrasonic element, Equipped with, The aforementioned enclosure is The reflective surface that reflects the ultrasonic waves, A waveguide for propagating the aforementioned ultrasonic waves, An opening is provided at one end of the waveguide through which the ultrasonic waves pass, It has, The length of the waveguide is longer than the width of the waveguide.

[0008] The double-feed detection device according to an application example of the present invention is: An ultrasonic device according to an application example of the present invention, comprising a transmitting ultrasonic device in which the transmitting and receiving surface transmits ultrasonic waves, An ultrasonic device according to an application example of the present invention, wherein the transmitting and receiving surface is a receiving ultrasonic device that receives the ultrasonic waves, Equipped with, The transmitting ultrasonic device and the receiving ultrasonic device are arranged on either side of the medium transport path. The transmitting ultrasonic device transmits the ultrasonic waves, the receiving ultrasonic device receives the ultrasonic waves that have passed through the medium, and detects double feeding of the medium based on the intensity of the received signal.

[0009] A transport device according to an application example of the present invention, The system is equipped with a double-feed detection device according to an application example of the present invention, and transports the medium along the transport path of the medium.

[0010] A scanner according to an application example of the present invention is A transport device according to an application example of the present invention, A reading unit that reads an image attached to the medium, is provided.

Brief Description of the Drawings

[0011] [Figure 1] It is a perspective view of the scanner according to the first embodiment viewed from the front. [Figure 2] It is a side sectional view showing the document conveyance path of the scanner in FIG. 1. [Figure 3] It is a block configuration diagram showing the control system of the scanner in FIG. 1. [Figure 4] It is a side sectional view showing the configuration of the double-feed detection device. [Figure 5] It is a side sectional view showing the configuration of the ultrasonic device. [Figure 6] It is a perspective view of the main board etc. shown in FIG. 5. [Figure 7] It is a side sectional view of the main part of the ultrasonic element shown in FIG. 6. [Figure 8] It is a diagram showing a model simulating the waveguide of the ultrasonic device in FIG. 5. [Figure 9] It is a simulation result obtained by three-dimensionally analyzing the sound pressure distribution in the plane intersecting the Pf axis of FIG. 5 when ultrasonic waves are transmitted from the ultrasonic device shown in FIG. 5. [Figure 10] It is a simulation result obtained by three-dimensionally analyzing the sound pressure distribution in the plane intersecting the Pe axis of FIG. 5 when ultrasonic waves are transmitted from the ultrasonic device shown in FIG. 5. [Figure 11] In the analysis shown in FIGS. 9 and 10, it is a simulation result showing how ultrasonic waves transmitted from the opening propagate in free space. [Figure 12] It is a simulation result obtained by analyzing the sound pressure distribution of an ultrasonic device having a waveguide that does not satisfy Equation (6). [Figure 13] It is a simulation result obtained by analyzing the sound pressure distribution of an ultrasonic device having a waveguide that does not satisfy Equation (6). [Figure 14]Figures 12 and 13 show the simulation results illustrating how ultrasound transmitted from the aperture propagates through free space. [Figure 15] This is a side cross-sectional view showing the configuration of an ultrasonic device according to the second embodiment. [Figure 16] This is a side cross-sectional view showing the configuration of an ultrasonic device according to the third embodiment. [Figure 17] This is a side cross-sectional view showing the configuration of an ultrasonic device according to the fourth embodiment. [Figure 18] Figure 17 is a perspective view of the protective member shown. [Modes for carrying out the invention]

[0012] The ultrasonic device, double-feed detection device, transport device, and scanner according to the present invention will be described in detail below based on the embodiments shown in the attached drawings.

[0013] 1. First Embodiment 1.1. Scanner Overview Figure 1 is a perspective view of the scanner 100 according to the first embodiment, viewed from the front. Figure 2 is a side cross-sectional view showing the document transport path of the scanner 100 in Figure 1. Figure 3 is a block diagram showing the control system of the scanner 100 in Figure 1.

[0014] The scanner 100 is a so-called sheet-feed type scanner. The scanner 100 comprises a transport device 95 shown in Figure 2, and a first reading unit 32 and a second reading unit 33 shown in Figure 2. The transport device 95 comprises a supply path R0, a transport path R1, a reading path R2, and an ejection path R3 shown in Figure 2, as well as a double-feed detection device 58. The transport device 95 transports the original document P shown in Figure 2 along a predetermined path. The double-feed detection device 58 detects double feeding of the original document P as it passes through the transport path R1. The first reading unit 32 reads the first side S1 of the original document P shown in Figure 2, and the second reading unit 33 reads the second side S2 of the original document P shown in Figure 2, which is opposite to the first side S1.

[0015] In the figures of this application, the three mutually orthogonal axes, the X-axis, Y-axis, and Z-axis, are illustrated with arrows. The direction along the X-axis is called the "X-direction," the direction along the Y-axis is called the "Y-direction," and the direction along the Z-axis is called the "Z-direction." Furthermore, the tip of each arrow is described as "plus," and the base is described as "minus."

[0016] As shown in Figure 1, the scanner 100 has a horizontally elongated rectangular shape when viewed from the front. In this embodiment, the width direction, which is the direction in which the longer side of the scanner 100 extends, is the X direction, the depth direction is the Y direction, and the height direction is the Z direction. The direction in which the document P is transported is called downstream, and the direction opposite to downstream is called upstream. In the following figures, dimensions and scales may differ from those of the actual documents for the sake of clarity.

[0017] As shown in Figure 1, the scanner 100 comprises a main body 70 and a stand 71 that supports the main body 70. The stand 71 is placed on a mounting surface 90 shown in Figure 2. The mounting surface 90 is a horizontal surface, such as the top surface of a desk.

[0018] As shown in Figures 1 and 2, the main body 70 includes a first unit 41, a second unit 42, and a third unit 43. The second unit 42 and the third unit 43 are rotatable together with respect to the first unit 41 around a pivot axis (not shown) parallel to the X-axis. Specifically, the lock on the second unit 42 and the third unit 43 to the first unit 41 can be released by sliding the locking member 72 shown in Figure 1 in the X-minus direction. The locking member 72 is a sliding open / close button that switches between engaging and disengaging the two units.

[0019] Furthermore, by rotating the second unit 42 and the third unit 43 relative to the first unit 41, a portion of the document transport path can be exposed. The document transport path refers to at least one of the supply path R0, transport path R1, reading path R2, and discharge path R3.

[0020] In particular, by opening the second unit 42 relative to the first unit 41, the supply path R0, the transport path R1, and the reading path R2 can be exposed. Also, by rotating the third unit 43 relative to the second unit 42, the discharge path R3 downstream from the reading path R2 can be exposed.

[0021] The third unit 43 is engaged with the second unit 42 by a snap-fit ​​structure (not shown). By applying an external force to the third unit 43, the engagement of the third unit 43 with the second unit 42 is released, and the third unit 43 can be opened.

[0022] The main body 70 rotates around the pivot axis 60 relative to the stand 71. This allows the main body 70 to assume two positions: a normal reading position and a booklet reading position.

[0023] The orientation of the main unit 70 shown in Figures 1 and 2 is the normal reading orientation. From this normal reading orientation, the main unit 70 is rotated so that the reading path R2 approaches horizontal. This allows transition to a booklet reading orientation (not shown). As shown in Figure 1, an operation unit 73 is provided on the front of the main unit 70. The operation unit 73 is equipped with several operation buttons 73a to 73c. ​​Functions such as a power button and a reading button are assigned to the operation buttons 73a to 73c, and they accept user operation.

[0024] 1.2. Manuscript transport route Next, the document transport path in scanner 100 will be explained with reference to Figure 2. In Figure 2, the thick dashed line shows the transport path through which the document P is transported.

[0025] In this document transport path, the supply path R0, transport path R1, reading path R2, and discharge path R3 are arranged in that order from the upstream side, transporting the document P from the document support unit 75 to the front surface 42b of the second unit 42. The front surface 42b is the output tray. Examples of documents P include sheet documents, card documents, booklet documents, etc.

[0026] The supply path R0 is the upstream section before the first roller pair 20. The transport path R1 is the section between the first roller pair 20 and the second roller pair 21. The reading path R2 is the section between the second roller pair 21 and the third roller pair 22.

[0027] The first unit 41 constitutes the lower part of the supply path R0, the transport path R1, and the reading path R2. The second unit 42 constitutes the upper part of the supply path R0, the transport path R1, and the reading path R2. The discharge path R3 is formed between the second unit 42 and the third unit 43.

[0028] In the normal reading position shown in Figure 2, the reading path R2 is connected to the ejection path R3 by the flap 35. In the booklet reading position, the flap 35 is in the position shown by the dashed line in Figure 2, and the reading path R2 is not connected to the ejection path R3. In this case, the original document P is ejected from the reading path R2 diagonally downward (Y-minus direction) in front of the main unit 70.

[0029] The normal scanning orientation is suitable for scanning images attached to sheet-like documents, i.e., documents P that have low rigidity and are easily bent. The booklet scanning orientation is suitable for scanning documents P that have high rigidity and are not easily bent, such as plastic cards and booklets.

[0030] As shown in Figure 2, the original document P is supported in an inclined position by the support section 74b and the document support section 75 before scanning. The support section 74b is the part of the upper cover 74 in Figure 1 that has rotated to stand upright. The upper cover 74 rotates around a rotation point (not shown) to open and close the document feeding opening for the original document P.

[0031] As shown in Figure 1, the document support unit 75 is housed inside the upper cover 74 when the upper cover 74 is closed. When the upper cover 74 is open, the two document support units 75 rotate and stand upright on top of the main unit 70, as shown by the dotted line in Figure 1, so that they can support the document P. The scanner 100 employs a so-called center feeding system, so that the center position of the document P in the X direction (width direction) is the same regardless of the size of the document P. The upper cover 74 and the document support units 75 are components of the first unit 41.

[0032] In Figure 2, when multiple documents P are set in the document support unit 75, the uppermost document P is fed downstream by the roller 20a of the first roller pair 20. The first roller pair 20 consists of a driving roller 20a and a driven roller 20b.

[0033] The roller 20a is provided on the second unit 42. The roller 20a is a drive roller that rotates by obtaining power from the transport motor 47 shown in Figure 3.

[0034] Roller 20b is provided in the first unit 41. Roller 20b faces roller 20a via the supply path R0. A torque limiter (not shown) is attached to roller 20b. This suppresses double feeding of the document P.

[0035] As shown in Figure 2, the transport direction of the document P in the transport path R1 is denoted as Pf. Note that the scanner configuration is not limited to a configuration in which the document is fed from the topmost document P, but may also be configured in which the lower roller 20b is a drive roller and roller 20a is a driven roller, and the document is fed from the bottommost document P.

[0036] A double-feed detection device 58 is provided in the transport path R1. The double-feed detection device 58 has an ultrasonic device 50a and an ultrasonic device 50b that are positioned opposite each other on either side of the transport path R1. The double-feed detection device 58 detects double feeding of the original document P as it passes through the transport path R1. Specifically, ultrasonic device 50a transmits ultrasound, and ultrasonic device 50b receives the ultrasound. In other words, the double-feed detection device 58 has a pair of ultrasonic devices, an ultrasonic device 50a for transmitting and an ultrasonic device 50b for receiving, and the ultrasonic devices 50a and 50b are positioned on either side of the transport path R1 (transport route) for the sheet-like original document P (medium). Ultrasonic device 50a transmits ultrasound, and ultrasonic device 50b receives the ultrasound that has passed through the original document P, and the double-feed of the original document P is detected based on the strength of the received signal.

[0037] A second pair of rollers 21 is provided downstream of the first pair of rollers 20. The second roller pair 21 consists of a roller 21a provided on the first unit 41 and a roller 21b provided on the second unit 42. The roller 21b is provided so as to be able to move back and forth relative to the roller 21a. The roller 21b is also pressed toward the roller 21a by a pressing member (not shown), such as a coil spring. As a result, the roller 21b moves back and forth relative to the roller 21a according to the thickness of the document P being transported. Both the roller 21a and the roller 21b are powered and rotated by the transport motor 47.

[0038] When the second unit 42 is closed relative to the first unit 41, rollers 21a and 21b come into contact. When the second unit 42 is opened relative to the first unit 41, rollers 21b and 21a move apart.

[0039] Downstream of the second roller pair 21, a first reading unit 32 and a second reading unit 33 are arranged opposite each other. The first reading unit 32 is provided in the first unit 41, and the second reading unit 33 is provided in the second unit 42.

[0040] The first reading unit 32 reads the first side S1 of the document P, and the second reading unit 33 reads the second side S2 of the document P opposite to the first side S1. The second reading unit 33 is provided so as to be able to move forward and backward relative to the first reading unit 32 and is pressed toward the first reading unit 32 by a pressing spring 34 (pressing member). As a result, the second reading unit 33 moves forward and backward relative to the first reading unit 32 according to the thickness of the document P being transported. Examples of the first reading unit 32 and the second reading unit 33 include contact-in-sensor (CISM) modules.

[0041] A third roller pair 22 is provided downstream of the first reading unit 32 and the second reading unit 33. The third roller pair 22 consists of a roller 22a provided on the first unit 41 and a roller 22b provided on the second unit 42. The roller 22b is provided so as to be able to move back and forth relative to the roller 22a. The roller 22b is also pressed toward the roller 22a by a pressing member (not shown), such as a coil spring. As a result, both the roller 22a and the roller 22b rotate by obtaining power from the transport motor 47.

[0042] When the second unit 42 is closed relative to the first unit 41, rollers 22a and 22b come into contact. When the second unit 42 is opened relative to the first unit 41, roller 22b separates from roller 22a. When the second unit 42 is opened, the first reading section 32 and the second reading section 33 are exposed, allowing for cleaning. At this time, the ultrasonic devices 50a and 50b are also exposed and can be cleaned together. For minor dirt, it is preferable to remove foreign matter with an air blower, and for stubborn dirt, it is preferable to clean with a cleaning solution.

[0043] A flap 35 is provided downstream of the third roller pair 22. The flap 35 rotates to switch between the two document transport paths described above. The flap 35 rotates in conjunction with the switching of the orientation of the main body 70. One configuration for rotating the flap 35 in conjunction with the switching of the orientation of the main body 70 is a configuration in which the flap 35 rotates mechanically in conjunction with the orientation of the main body 70 by an interlocking mechanism, such as a cam mechanism (not shown). However, the configuration is not limited to this, and the flap 35 may be rotated by a solenoid (not shown).

[0044] The discharge path R3 is also called the U-turn path because it causes the document P, which has been transported in the Z-minus direction, to make a U-turn along the flap 35 and be discharged in the Z-plus direction.

[0045] The discharge path R3 is provided with a fourth roller pair 23 and a fifth roller pair 24. The fourth roller pair 23 consists of a roller 23a provided on the third unit 43 and a roller 23b provided on the second unit 42. Roller 23b is provided so as to be able to move back and forth relative to roller 23a. Roller 23b is also pressed toward roller 23a by a pressing member (not shown), such as a coil spring. As a result, roller 23b moves back and forth relative to roller 23a according to the thickness of the document P being transported. Roller 23a is a driven roller driven by the transport motor 47. Roller 23b is a driven roller.

[0046] The fifth roller pair 24 consists of a roller 24a provided on the third unit 43 and a roller 24b provided on the second unit 42. The roller 24b is provided so as to be able to move back and forth relative to the roller 24a. The roller 24b is also pressed toward the roller 24a by a pressing member (not shown), such as a coil spring. As a result, the roller 24b moves back and forth relative to the roller 24a according to the thickness of the document P being transported. The roller 24a is a driven roller driven by the transport motor 47. The roller 24b is a driven roller.

[0047] When the third unit 43 is closed relative to the second unit 42, rollers 23a and 23b come into contact. Similarly, rollers 24a and 24b come into contact.

[0048] When the third unit 43 is opened relative to the second unit 42, rollers 23a and 23b separate. Similarly, rollers 24a and 24b separate.

[0049] The original document P, having passed through the discharge path R3, is discharged in the Z-positive direction by the fifth roller pair 24 and supported in an inclined position by the front surface 42b of the second unit 42.

[0050] 1.3. Control System Next, we will explain the control system of the scanner 100 shown in Figure 3.

[0051] The control unit 80 comprises an arithmetic unit 81 having one or more processors, and a storage unit 85 composed of non-volatile memory and volatile memory.

[0052] The control unit 80 is connected to the first reading unit 32, the second reading unit 33, the transport motor 47, and the double-feed detection device 58, and the control unit 80 controls these in an overall manner.

[0053] The transport motor 47 is the drive source for rollers 20a, 21a, 21b, 22a, 22b, 23a, and 24a. Although each roller may have its own individual drive motor, in Figure 3 they are shown as part of the same functional block.

[0054] As shown in Figure 3, the scanner 100 includes an interface unit 86 that connects an external device 87 and a control unit 80.

[0055] The control unit 80 receives various data and signals input from external devices 87, such as a personal computer, via the interface unit 86. The control unit 80 also outputs the data read by the scanner 100 to the external devices 87.

[0056] The memory unit 85 stores various data and programs for controlling the scanner 100.

[0057] The calculation unit 81 reads and executes various programs stored in the storage unit 85 to realize the functions of the transport control unit 82, the read control unit 83, and the double-feed determination unit 84.

[0058] The transport control unit 82 controls the transport motor 47 to rotate the aforementioned rollers, thereby feeding, transporting, and ejecting the original document P.

[0059] The reading control unit 83 controls the first reading unit 32 and the second reading unit 33 while the document P is being transported, causing them to read the image of the document P.

[0060] The double-feed detection unit 84 detects the state of the original document P and determines whether the original document P has been double-feeded based on the received signal output from the double-feed detection device 58.

[0061] As described above, the double-feed detection device 58 includes an ultrasonic device 50a that transmits ultrasonic waves and an ultrasonic device 50b that receives ultrasonic waves. The ultrasonic device 50a includes an ultrasonic element 10 and a transmitting / receiving circuit 55. The ultrasonic device 50b also includes an ultrasonic element 10 and a transmitting / receiving circuit 55. Each transmitting / receiving circuit 55 can be switched between transmitting and receiving ultrasonic waves. That is, the transmitting / receiving circuit 55 of the ultrasonic device 50a functions as a transmitting circuit that transmits ultrasonic waves, causing the ultrasonic element 10 to emit ultrasonic waves of a frequency corresponding to the drive signal. The transmitting / receiving circuit 55 of the ultrasonic device 50b functions as a receiving circuit that receives ultrasonic waves, detecting the signal level of the ultrasonic waves incident on the ultrasonic element 10. Alternatively, a configuration with a dedicated transmitting circuit or receiving circuit may be provided. The double-feed determination unit 84 determines that the document P is being double-feeded if the voltage value of the received signal from the ultrasonic device 50b is smaller than a predetermined threshold. If the double-feed determination unit 84 determines that a double-feed has occurred, the transport control unit 82 stops transporting the document P.

[0062] 1.4. Double Feed Detection Device Figure 4 is a side cross-sectional view showing the configuration of the double-feed detection device 58. Figure 4 illustrates the side cross-sections of the main parts of ultrasonic devices 50a and 50b facing each other via the transport path R1. In Figure 4, the coordinate axes are defined as three mutually orthogonal axes: the X-axis, the transport direction Pf of the original document P, and the perpendicular direction Pe, which is perpendicular to the transport direction Pf.

[0063] The ultrasonic devices 50a and 50b shown in Figure 4 each include a housing 11. The ultrasonic waves emitted from the ultrasonic element 10 of the ultrasonic device 50a (transmitting ultrasonic device) propagate through the waveguide 14, are reflected by the reflective surface 13 of the housing 11, and then are emitted again through the waveguide 14 from the opening 12. Subsequently, the emitted ultrasonic waves pass through the transport path R1 and are incident on the ultrasonic device 50b (receiving ultrasonic device). In this embodiment, the ultrasonic devices 50a and 50b have the same configuration. Therefore, the ultrasonic waves that have passed through the transport path R1 are incident on the ultrasonic device 50b from the opening 12, are reflected by the reflective surface 13 through the waveguide 14, and then are incident on the ultrasonic element 10 of the ultrasonic device 50b through the waveguide 14 again.

[0064] Figure 4 illustrates the propagation path of the ultrasonic beam emitted from the ultrasonic element 10 of the ultrasonic device 50a, with the central axis 65 being used as the central axis. In other words, the ultrasonic waves propagate along the central axis 65. More specifically, the ultrasonic waves are emitted from the ultrasonic element 10 of the ultrasonic device 50a around the central axis 65a, reflected by the reflective surface 13, propagate around the central axis 65b, reflected by the reflective surface 13 on the receiving side, propagate around the central axis 65c, and enter the ultrasonic element 10 of the ultrasonic device 50b. Note that the central axes 65a to 65c are collectively referred to as the central axis 65.

[0065] The central axis 65b (perpendicular to the opening 12) may be perpendicular to the transport path R1, but in Figure 4 it is inclined at an angle θ. In other words, it is preferable that the central axis 65b is inclined rather than perpendicular to the document P to which the ultrasound is irradiated. By inclining the central axis 65b with respect to the transport path R1 in this way, multiple reflections of ultrasound between the document P and the ultrasound device 50a can be suppressed. Specifically, if the central axis 65b coincides with the perpendicular direction of the document P, that is, if the angle θ of the central axis 65b with respect to the document P is 90°, there is a risk that the ultrasound emitted from the ultrasound element 10 will be reflected multiple times between the document P and the ultrasound element 10.

[0066] The angle θ is preferably 50° or more and less than 90°, and more preferably 60° or more and 80° or less.

[0067] 1.5.Ultrasonic device Figure 5 is a side cross-sectional view showing the configuration of the ultrasonic device 50a. Figure 6 is a perspective view of the main substrate 9, etc., shown in Figure 5. Figure 7 is a side cross-sectional view of the main part of the ultrasonic element 10 shown in Figure 6. Here, the configuration of the ultrasonic device 50a shown in Figure 5 will be described as representative, but the configuration of the ultrasonic device 50b shown in Figure 4 is the same as the ultrasonic device 50a, only the arrangement is different. Note that it is not necessary for the configuration of the ultrasonic device 50b to be the same as the configuration of the ultrasonic device 50a, and the two may be different from each other.

[0068] The ultrasonic device 50a shown in Figure 5 includes a main circuit board 9 in addition to the ultrasonic element 10 and housing 11 described above.

[0069] The housing 11 is a case for housing the ultrasonic element 10. As shown in Figure 5, the housing 11 has a base portion 11a which is a plate-shaped portion substantially parallel to the transport path R1, a first wall 11b extending from the base portion 11a along the central axis 65a, a second wall 11c extending from the base portion 11a along the central axis 65b, and a third wall 11d facing the second wall 11c. The first wall 11b and the second wall 11c are provided to open in a V-shape from the base portion 11a. The inner surface of the base portion 11a is a flat reflective surface 13.

[0070] The inner surfaces of the first wall 11b and the third wall 11d are waveguides 14 that propagate ultrasonic waves emitted from the ultrasonic element 10 to the reflective surface 13. The central axis 65a passes through the center of this waveguide 14. The surface of the ultrasonic element 10 is called the transmitting / receiving surface 10a. The central axis 65a is perpendicular to the transmitting / receiving surface 10a.

[0071] An opening 12 is formed at the ends of the second wall 11c and the third wall 11d. In other words, the opening 12 is provided at one end of the waveguide 14, allowing the ultrasonic waves propagated by the waveguide 14 to pass through and be emitted into free space. The opening 12 has a rectangular shape when viewed from the side of the transport path R1. The inner surfaces of the second wall 11c and the third wall 11d are waveguides 14 that propagate the ultrasonic waves reflected by the reflective surface 13 to the opening 12. The central axis 65b passes through the center of this waveguide 14. The central axis 65b is also perpendicular to the opening 12.

[0072] Therefore, in the ultrasonic device 50a shown in Figure 5, the waveguide 14 is composed of two parts connected by a reflective surface 13 provided in the middle. The part extending from the ultrasonic element 10 to the reflective surface 13 (the part extending along the central axis 65a) is called the "first part 141," and the part extending from the reflective surface 13 to the opening 12 (the part extending along the central axis 65b) is called the "second part 142."

[0073] With this configuration, the ultrasonic waves emitted from the ultrasonic element 10 shown in Figure 5 are reflected by the reflective surface 13 and emitted from the opening 12. In other words, the ultrasonic element 10 cannot be directly seen through the opening 12. Therefore, even if foreign matter enters the waveguide 14 through the opening 12, the probability of it adhering to the transmitting / receiving surface 10a of the ultrasonic element 10 can be reduced.

[0074] Examples of materials that can be used to construct the housing 11 include metal and resin. If the housing 11 is made of metal, a shielding effect can be obtained to protect the ultrasonic element 10 from the effects of static electricity and electromagnetic waves. If the housing 11 is made of resin, the housing 11 can be efficiently formed by injection molding. For example, in the housing 11 shown in Figure 5, if the part including the base 11a and the parts including the first wall 11b, second wall 11c, and third wall 11d are each made as injection molded parts, the molding efficiency will be increased.

[0075] A main circuit board 9 is mounted between the end of the first wall 11b and the end of the third wall 11d. An ultrasonic element 10 is mounted on the main circuit board 9.

[0076] As shown in Figure 6, the main circuit board 9 is a rectangular circuit board. Notches 9a for screw fastening are provided on both short sides of the main circuit board 9.

[0077] The surface of the main circuit board 9 is mounted with an ultrasonic element 10, a transmitting / receiving circuit 55, a cover member 76, and the like. The ultrasonic element 10 is a rectangular component when viewed from above.

[0078] As shown in Figure 7, the ultrasonic element 10 comprises a base substrate 8, an element substrate 3 superimposed on it, and a vibrating part 7. The base substrate 8 is a mounting substrate and has a plurality of terminals (not shown) on its lower surface. The element substrate 3 comprises a semiconductor substrate 1 and a diaphragm 2.

[0079] An example of a semiconductor substrate 1 is a silicon substrate. The semiconductor substrate 1 has multiple through-holes, or openings 1a, arranged in a grid pattern. The openings 1a are separated by partition walls 1b.

[0080] The diaphragm 2 is composed of, for example, a laminate in which multiple SiO2 films are stacked. However, the configuration of the diaphragm 2 is not limited to this, and it may be a laminate in which multiple layers of SiO2 films and ZrO2 films are stacked alternately. The diaphragm 2 is provided on the surface of the semiconductor substrate 1 on the base substrate 8 side so as to cover multiple openings 1a.

[0081] A vibrating section 7 is provided in the portion 2a of the diaphragm 2 that overlaps with the opening 1a. The vibrating section 7 shown in Figure 7 consists of a first electrode 4, a piezoelectric element 5, and a second electrode 6, which are laminated on the diaphragm 2. The first electrode 4 is a solid electrode and is provided to cover all of the openings 1a and the partition wall 1b. The piezoelectric element 5 is selectively provided in the portion 2a that overlaps with the opening 1a. Examples of materials for the piezoelectric element 5 include, but are not limited to, lead zirconate titanate (PZT). The second electrode 6 is provided in a stripe shape along the direction of extension of the short side of the main substrate 9, for example. A space is provided between the vibrating section 7 and the base substrate 8 so as not to hinder the vibration of the vibrating section 7.

[0082] As shown in Figure 7, one ultrasonic transducer Tr is formed by a vibrating section 7 provided corresponding to the opening 1a. Then, as shown in Figure 6, multiple ultrasonic transducers Tr are arranged in a matrix on the transmitting / receiving surface 10a of the ultrasonic element 10. The ultrasonic transducers Tr are electrically connected to the transmitting / receiving circuit 55.

[0083] The surface of the main circuit board 9 shown in Figure 6 is provided with a metal cover member 76 that covers the ultrasonic element 10 and the transmitting / receiving circuit 55. The cover member 76 has an opening 76a that exposes the transmitting / receiving surface 10a of the ultrasonic element 10. The cover member 76 is supplied with a power potential such as GND, protecting the ultrasonic element 10 and the transmitting / receiving circuit 55 from static electricity and electromagnetic waves. Note that the cover member 76 is not essential and may be omitted if the housing 11 is made of metal and has shielding properties.

[0084] A connector 77 is mounted on the back of the main board 9. A cable (not shown) is connected to the connector 77. This electrically connects the ultrasonic device 50a to the control unit 80 shown in Figure 3.

[0085] In FIG. 5, a cross-section in the short side direction of the main board 9 is shown. The main board 9 is screwed and fixed to the housing 11 by two cutout holes 9a shown in FIG. 6, which are provided before and after in the depth direction (X direction).

[0086] FIG. 8 is a diagram showing a model M simulating the waveguide 14 of the ultrasonic device 50a in FIG. 5.

[0087] The model M shown in FIG. 8 is obtained by linearly extending the waveguide 14 shown in FIG. 5 and simplifying it into a rectangle with length L and width D. One short side of the model M is the transmission / reception surface 10a, and the other short side is the opening 12. Therefore, the length L is the sum of the length of the central axis 65a from the transmission / reception surface 10a of the ultrasonic element 10 to the reflection surface 13 and the length of the central axis 65b from the reflection surface 13 to the opening 12. Also, the width D represents the length in the direction orthogonal to the central axes 65a and 65b within the cross-section shown in FIG. 5 and the length in the direction orthogonal to the cross-section shown in FIG. 5, respectively.

[0088] In the ultrasonic device 50a according to the present embodiment, the waveguide 14 is configured such that the length L is longer than the width D. That is, in the model M, D < L holds. The ultrasonic wave emitted from one short side of the model M is divided into a component that propagates substantially parallel along the long side and a component that is reflected by the inner surface of the model M. These components strengthen or weaken each other by interference, but when D < L holds, the probability of strengthening in the vicinity of the opening 12 is higher than when L ≤ D holds. As a result, an ultrasonic device 50a capable of transmitting an ultrasonic wave with a high sound pressure in the vicinity of the opening 12 can be realized. Also, an ultrasonic device 50b capable of receiving an ultrasonic wave with high sensitivity can be realized.

[0089] Therefore, by having an opening 12, a reflective surface 13, and a waveguide 14 in the housing 11, and by satisfying the above-described relationship between the length L and width D of the waveguide 14, it is possible to realize an ultrasonic device 50a in which foreign matter is less likely to adhere to the transmitting / receiving surface 10a of the ultrasonic element 10 and ultrasonic waves can be transmitted at high sound pressure, or an ultrasonic device 50b in which foreign matter is less likely to adhere to the transmitting / receiving surface 10a of the ultrasonic element 10 and ultrasonic waves can be received with high sensitivity.

[0090] Furthermore, by providing such ultrasonic devices 50a and 50b, it is possible to realize a double-feed detection device 58 that is easy to maintain and has high accuracy in determining double-feeds.

[0091] Furthermore, by incorporating such a double-feed detection device 58, it is possible to realize a conveying device 95 that is easy to maintain and has high accuracy in detecting double feeds.

[0092] Furthermore, by incorporating such a transport device 95, it is possible to realize a scanner 100 that is easy to maintain, has high accuracy in detecting double feeds, and is easy to handle.

[0093] Furthermore, it is preferable that the length of the first portion 141 in the direction extending along the central axis 65a (perpendicular to the transmitting / receiving surface 10a) is longer than the width of the first portion 141. In addition, it is preferable that the length of the second portion 142 in the direction extending along the central axis 65b (perpendicular to the opening 12) is longer than the width of the second portion 142.

[0094] With this configuration, ultrasonic attenuation is more easily suppressed in both the first part 141 and the second part 142. Therefore, an ultrasonic device 50a capable of transmitting ultrasonic waves at a higher sound pressure, or an ultrasonic device 50b capable of receiving ultrasonic waves with higher sensitivity, can be realized.

[0095] Furthermore, the length L of model M is preferably optimized based on the wavelength λ and propagation angle α of the ultrasound emitted from the ultrasonic element 10. This increases the probability of constructive interference of ultrasound in the vicinity of the aperture 12. This effect can be explained using the following formula.

[0096] The solid line drawn inside Model M in Figure 8 represents the propagation path r1 of the ultrasonic component that propagates approximately parallel to the long side of Model M, from the ultrasonic waves emitted from one of the short sides of Model M. The dashed line drawn in Figure 8 represents the propagation path r2 of the component that is reflected from the inner surface of Model M. In Model M shown in Figure 8, as an example, propagation paths r1 and r2 intersect at the midpoint of length L and at the aperture 12. In other words, interference occurs at these two locations. Hereafter, these two locations will be referred to as interference points i1 and i2. In designing the waveguide 14, it is necessary to optimize the length L and width D so that the two components interfere reinforcely with each other at the aperture 12. An example of the calculation formula is explained below.

[0097] In Model M shown in Figure 8, propagation path r2 intersects propagation path r1 at propagation angle α. Furthermore, let X1 be the distance from the transmitting / receiving surface 10a to the interference point i1 (midpoint of length L), and let X2 be the distance from the transmitting / receiving surface 10a to the point where propagation path r2 is first reflected by the inner wall surface of Model M. In this case, the path difference Δp between distance X1 and distance X2 is expressed by the following equation (1).

[0098]

number

[0099] When this path difference Δp is an integer multiple of the ultrasonic wavelength λ, constructive interference occurs at the interference point i1. In this case, the path difference Δp is expressed by equation (2) below, using the wavelength λ.

[0100]

number

[0101] In equation (2) above, n is an integer. Thus, equation (3) below can be derived from equations (1) and (2) above.

[0102]

number

[0103] Furthermore, by rearranging equation (3) above, we can derive equation (4) below.

[0104]

number

[0105] In equation (4) above, the distance X1 is expressed in terms of wavelength λ. To extend this distance X1 to the length L, which is the total length of model M, we replace the distance X1 in equation (4) with length L. In other words, we assume that only interference point i2 exists in model M (interference point i1 does not exist). Then, the condition for constructive interference to occur at the opening 12 is expressed in equation (5) below.

[0106]

number

[0107] In equation (5) above, k is an integer. Therefore, in designing the waveguide 14, the length L and width D should be set such that equation (5) above holds true.

[0108] Note that equation (5) above represents the most ideal design value. In designing the waveguide 14, it is preferable to satisfy equation (6) below.

[0109]

number

[0110] By designing the waveguide 14 to satisfy equation (6) above, the probability of constructive interference occurring at the aperture 12 can be particularly increased. This makes it possible to realize an ultrasonic device 50a capable of transmitting ultrasonic waves at a higher sound pressure, or an ultrasonic device 50b capable of receiving ultrasonic waves with higher sensitivity. Furthermore, it is possible to realize a double-feed detection device 58 with high accuracy in determining double-feeds.

[0111] The integer k in equation (6) above is not particularly limited, but is preferably set to a value such that the width D of the waveguide 14 is 1 / 5 or less of the length L of the waveguide 14. This ensures that the propagation angle α falls within an appropriate range, thereby realizing an ultrasonic device 50a capable of transmitting ultrasonic waves with high sound pressure near the opening 12, or an ultrasonic device 50b capable of receiving ultrasonic waves with high sensitivity.

[0112] The length L is preferably, for example, 15 mm to 40 mm, and more preferably 18 mm to 30 mm.

[0113] Furthermore, the width D is preferably, for example, 1 mm to 10 mm, and more preferably 2 mm to 5 mm.

[0114] As mentioned above, width D represents the length in the direction perpendicular to the central axes 65a and 65b within the cross-section shown in Figure 5, and the length in the direction perpendicular to the cross-section shown in Figure 5. These lengths may be the same or different from each other.

[0115] On the other hand, in model M shown in Figure 8, if interference points i1 and i2 exist, it is desirable to optimize the positional relationship between interference point i1 and the reflective surface 13.

[0116] Specifically, it is preferable that the interference point i1 is located between the ultrasonic element 10 and the reflective surface 13, and more preferably located directly in front of the reflective surface 13. This allows the component propagating along propagation path r1 and the component propagating along propagation path r2 to be incident on the reflective surface 13 in a narrowly focused state. As a result, variations in the reflection angle of the ultrasonic waves at the reflective surface 13 can be suppressed. Note that "directly in front of the reflective surface 13" refers, for example, to a range within 1 / 4 of the length of the central axis 65a from the reflective surface 13.

[0117] Furthermore, while Model M shown in Figure 8 simplifies the model by not considering the near-field limit distance, it may be necessary to consider it. The near-field limit distance refers to the distance over which the effects of disturbances in the near-field range of ultrasonic waves generated by the ultrasonic element 10 extend. When the size of the transmitting / receiving surface 10a of the ultrasonic element 10 is d, the near-field limit distance X0 is given by X0 = d 2 It can be calculated as / (4λ). Therefore, when determining the design value of the waveguide length L of waveguide 14, you may use the value obtained by adding the near-field limit distance X0 to the value calculated by the above equations (1) to (6).

[0118] Furthermore, the interference point i2 may be designed to be shifted outward from the aperture 12. If the amount of this shift is F0, then the amount of shift F0 can be determined by calculation or experiment. For example, an approximate formula obtained from experimentation is F0 = 0.0162 × D 3.8076 The amount of shift F0 may be calculated based on the above. In this case, the design value of the waveguide length L may be the value obtained by subtracting the amount of shift F0 from the value calculated by equations (1) to (6) above.

[0119] Furthermore, as shown in Figure 5, the reflective surface 13 is located on the central axis 65a and the central axis 65b. The central axis 65a and the central axis 65b are inclined with respect to the normal 61 of the reflective surface 13. In other words, the normal 61 of the reflective surface 13 is inclined with respect to both the central axis 65a (perpendicular to the transmitting / receiving surface 10a) and the central axis 65b (perpendicular to the opening 12).

[0120] With this configuration, the probability of the ultrasonic waves emitted from the ultrasonic element 10 shown in Figure 5 being reflected by the reflective surface 13 and emitted from the opening 12 can be increased. In addition, the probability of the ultrasonic waves reflected by the reflective surface 13 returning to the ultrasonic element 10 can be reduced. As a result, the sound pressure of the ultrasonic waves emitted from the opening 12 can be sufficiently increased.

[0121] Furthermore, by changing the propagation direction of the ultrasonic waves via the reflective surface 13, it becomes possible to house the ultrasonic element 10 inside the housing 11. As a result, even if foreign matter such as paper dust enters the inside of the housing 11 through the opening 12, the foreign matter remains on the reflective surface 13, thereby reducing the probability of foreign matter adhering to the transmitting / receiving surface 10a of the ultrasonic element 10. This suppresses attenuation of the ultrasonic waves emitted from the ultrasonic element 10 due to foreign matter. In addition, foreign matter remaining on the reflective surface 13 can be easily cleaned, for example, by air blowing, as will be described later.

[0122] Furthermore, the ultrasonic device 50b can increase the reception sensitivity of ultrasonic waves incident from the opening 12, reduce the probability of foreign matter adhering to the ultrasonic element 10, and allow for easy removal of foreign matter.

[0123] The central axes 65a and 65b shown in Figure 5 are inclined in opposite directions via the normal 61 of the reflective surface 13.

[0124] With this configuration, the ultrasonic waves emitted from the ultrasonic element 10 shown in Figure 5 can be reflected by the reflective surface 13 and then emitted from the opening 12 while suppressing the attenuation of the ultrasonic waves. This makes it possible to realize an ultrasonic device 50a capable of transmitting ultrasonic waves with high sound pressure.

[0125] In this case, it is preferable that the angle between the normal 61 and the central axis 65a (the angle of incidence of ultrasonic waves on the reflective surface 13) is equal to the angle between the normal 61 and the central axis 65b (the angle of reflection of ultrasonic waves on the reflective surface 13). This increases the reflection efficiency of ultrasonic waves on the reflective surface 13, allowing high-sound-pressure ultrasonic waves to be transmitted from the opening 12.

[0126] In this specification, "angles are equal" means that the difference between two angles is 5° or less. Furthermore, it is not mandatory for the two angles to be equal; they may be different.

[0127] The central axis 65a (perpendicular to the transmitting / receiving surface 10a) and the central axis 65b (perpendicular to the opening 12), as shown in Figure 5, intersect each other on the reflective surface 13.

[0128] With this configuration, when ultrasonic waves propagating along the central axis 65a are reflected by the reflective surface 13, the reflection efficiency can be sufficiently increased. This makes it possible to realize an ultrasonic device 50a capable of transmitting high-sound-pressure ultrasonic waves from the opening 12. Furthermore, it is possible to realize an ultrasonic device 50b capable of receiving ultrasonic waves with high sensitivity.

[0129] Figure 9 shows the simulation results obtained by analyzing the sound pressure distribution in three dimensions in a plane intersecting the Pf axis in Figure 5 when ultrasound is transmitted from the ultrasonic device 50a shown in Figure 5. The horizontal axis of Figure 9 represents the position in the X direction in Figure 5, and the vertical axis of Figure 9 represents the position in the Pe direction in Figure 5. The sound pressure distribution in Figure 9 is the distribution at a position 10 mm away from the opening 12 shown in Figure 5 in the X-plus direction. In Figure 9, the area enclosed by the ring-shaped light-colored region indicates that the sound pressure is relatively higher compared to the surrounding area.

[0130] In Figure 9, the central part of the horizontal axis and the lower end of the vertical axis are the points closest to the opening 12. In Figure 9, a single light-colored annular region is observed in this area. The color gradually changes from this light-colored annular region outwards to the surrounding area.

[0131] Figure 10 shows the simulation results obtained by analyzing the sound pressure distribution in three dimensions in a plane intersecting the Pe axis in Figure 5 when ultrasonic waves are transmitted from the ultrasonic device 50a shown in Figure 5. The horizontal axis of Figure 10 represents the position in the Pf direction in Figure 5, and the vertical axis of Figure 10 represents the position in the X direction in Figure 5.

[0132] In Figure 10, the central point on both the horizontal and vertical axes is the area closest to the opening 12. In Figure 10, a single light-colored annular region is visible in this area. The color gradually changes from this light-colored annular region outwards.

[0133] The simulation results shown in Figures 9 and 10 suggest the existence of a so-called unimodal sound pressure distribution, as there is only one sound pressure peak. In a unimodal sound pressure distribution, it is easy to concentrate the ultrasonic energy at the peak. Therefore, it is possible to realize an ultrasonic device 50a capable of transmitting ultrasonic waves at high sound pressure, or an ultrasonic device 50b capable of receiving ultrasonic waves with high sensitivity. Furthermore, the double-feed detection device 58 can improve the signal-to-noise ratio (S / N ratio) of the received signal, thereby particularly improving the accuracy of double-feed detection.

[0134] Figure 11 shows the simulation results illustrating how the ultrasonic waves transmitted from the aperture 12 propagate through free space FS in the analysis shown in Figures 9 and 10.

[0135] The simulation results shown in Figure 11 show that ultrasound with a unimodal sound pressure distribution propagates while maintaining a unimodal sound pressure distribution even in free space FS. Therefore, the simulation results shown in Figure 11 suggest that the sound pressure of ultrasound passing through the document P can be sufficiently increased by using the ultrasound device 50a that satisfies equation (6) above. Similarly, it suggests that the ultrasound device 50b that satisfies equation (6) above can be received with higher sensitivity by using the ultrasound device 50b that satisfies equation (6) above.

[0136] The waveguide 14 of the ultrasonic device 50a shown in Figure 5 is designed to satisfy equation (6) above. Therefore, the above simulation results support the usefulness of satisfying equation (6) above.

[0137] Figures 12 and 13 also show simulation results that differ from those described above. The simulation results shown in Figures 12 and 13 were obtained by analyzing the sound pressure distribution for an ultrasonic device having a waveguide that does not satisfy equation (6) above. Figures 12 and 13 are the same as Figures 9 and 10, except that the design conditions of the waveguide being simulated are different.

[0138] The simulation results shown in Figures 12 and 13 suggest the existence of a so-called bimodal sound pressure distribution, as there are two sound pressure peaks. In a bimodal sound pressure distribution, the energy at the peaks is dispersed, causing the sound pressure to decrease.

[0139] Figure 14 shows the simulation results illustrating how ultrasound transmitted from the aperture propagates through free space (FS) in the analyses shown in Figures 12 and 13.

[0140] The simulation results shown in Figure 14 show how ultrasound with a bimodal sound pressure distribution propagates in free space (FS). Compared to the simulation results shown in Figure 11, the simulation results in Figure 14 show that the ultrasound attenuates immediately after being emitted into free space (FS).

[0141] 2. Second Embodiment Next, an ultrasonic device according to the second embodiment will be described. Figure 15 is a side cross-sectional view showing the configuration of the ultrasonic device 50a according to the second embodiment.

[0142] The second embodiment will be described below, focusing on the differences from the first embodiment, and similar matters will be omitted from the description. In Figure 15, components identical to those in the first embodiment are denoted by the same reference numerals.

[0143] The ultrasonic device 50a shown in Figure 15 is the same as the ultrasonic device 50a shown in Figure 5, except that the configuration of the housing 11 is different. The configuration of the ultrasonic device 50a, described later, is also applicable to the ultrasonic device 50b.

[0144] The housing 11 shown in Figure 15 has a first discharge hole 151. The first discharge hole 151 does not need to be located in a position different from the opening 12 of the housing 11, but in Figure 15 it is located in the first wall 11b. In particular, in Figure 15 the first discharge hole 151 is provided so as to penetrate the portion of the first wall 11b adjacent to the base 11a. As a result the first discharge hole 151 faces the reflective surface 13, so even if foreign matter enters from the opening 12 as shown by the white arrow in Figure 15, it becomes easier to discharge the foreign matter through the first discharge hole 151. Specifically, by blowing air towards the opening 12 using an air duster or the like (not shown), foreign matter can be easily discharged from the first discharge hole 151 by being carried by the airflow. As a result, an ultrasonic device 50a can be realized in which foreign matter is less likely to adhere to the transmitting and receiving surface 10a of the ultrasonic element 10.

[0145] Furthermore, the cross-sectional shape of the first discharge hole 151 shown in Figure 15 (the cross-sectional shape of the plane perpendicular to the Pf axis) is preferably elongated horizontally in the X direction along the reflective surface 13. This allows foreign matter accumulated on the reflective surface 13 to be discharged more efficiently through the first discharge hole 151.

[0146] Furthermore, the placement of the first discharge hole 151 is not limited to the above position, but can be any position that allows foreign matter that has entered the waveguide 14 to be discharged. This provides the effect of easily discharging foreign matter through the first discharge hole 151.

[0147] The following describes an example of the design procedure for the waveguide 14 provided with the first discharge hole 151. In the following description, of the width D of the Model M described above, the length in the direction perpendicular to the central axis 65a within the cross-section shown in Figure 15 is defined as "width w1", and the length in the direction perpendicular to the central axis 65b is defined as "width w2". Furthermore, of the width D, the length on the central axis 65a in Figure 15 perpendicular to the cross-section of Figure 15 is defined as "depth d1", and the length on the central axis 65b in Figure 15 perpendicular to the cross-section of Figure 15 is defined as "depth d2". In addition, of the length L, the length on the central axis 65a in Figure 15 is defined as "length L1", and the length on the central axis 65b in Figure 15 is defined as "length L2".

[0148] First, the depths d1 and d2 are tentatively determined according to the size of the ultrasonic element 10. Preferably, the depths d1 and d2 are longer than 1 times the length of the ultrasonic element 10 in its extending direction, but less than 3 times.

[0149] Next, based on the depths d1 and d2, the first provisional lengths L1 and L2 are calculated using equations (1) to (6) above. It is assumed that the reflective surface 13 is located immediately after the interference point i1 shown in Figure 8.

[0150] Next, the widths w1 and w2 are tentatively set to the same values ​​as the depths d1 and d2. Then, based on the tentatively set widths w1 and w2, the second tentative lengths L1 and L2 are calculated using the above formulas (1) to (6).

[0151] Next, the length L1 is determined by averaging the first provisional length L1 and the second provisional length L1. Similarly, the length L2 is determined by averaging the first provisional length L2 and the second provisional length L2.

[0152] Next, the optimal widths w1 and w2 are determined by simulation using the difference L1-L3 (the difference obtained by subtracting the opening length L3 of the first discharge hole 151 from the determined length L1) and the determined length L2. In the simulation, values ​​are estimated that yield a unimodal sound pressure distribution as shown in Figures 9 and 10, while varying the widths w1 and w2. The opening length L3 only needs to be long enough for a cleaning tool to enter the first discharge hole 151, for example, so it should be between 2 mm and 5 mm.

[0153] Next, we compare the widths w1 and w2 estimated by the simulation with the tentatively determined widths w1 and w2. We repeat the simulation until the difference between the two is less than 1% of the tentatively determined w1 and w2. The widths w1 and w2 at the end of the simulation are then determined. In this way, the widths w1 and w2, depths d1 and d2, and lengths L1 and L2 can be determined.

[0154] If lengths L1 and L2 are changed during the simulation, they may be compared to the lengths L1 and L2 determined before the simulation. In this case, the simulation may be repeated until the difference between the two is less than or equal to 1% of the lengths L1 and L2 determined before the simulation. The lengths L1 and L2 at the end of the simulation can then be considered the determined values. In the second embodiment described above, the same effects as in the first embodiment can be obtained.

[0155] 3. Third Embodiment Next, an ultrasonic device according to the third embodiment will be described. Figure 16 is a side cross-sectional view showing the configuration of the ultrasonic device 50a according to the third embodiment.

[0156] The third embodiment will be described below, focusing on the differences from the second embodiment, and similar matters will be omitted from the explanation. In Figure 16, components identical to those in the second embodiment are denoted by the same reference numerals. The ultrasonic device 50a shown in Figure 16 is the same as the ultrasonic device 50a shown in Figure 15, except that the configuration of the housing 11 is different. The configuration of the ultrasonic device 50a, described later, is also applicable to the ultrasonic device 50b.

[0157] The housing 11 shown in Figure 16 has a second discharge hole 152. The second discharge hole 152 does not need to be located in a position different from the opening 12 and the first discharge hole 151, but in Figure 16 it is located in the second wall 11c. In particular, in Figure 16 the second discharge hole 152 is provided so as to penetrate the portion of the second wall 11c adjacent to the base 11a. As a result the second discharge hole 152 faces the reflective surface 13, so even if foreign matter enters through the opening 12 as shown by the white arrow in Figure 16, the foreign matter can be discharged more easily through the first discharge hole 151 or the second discharge hole 152. As a result, an ultrasonic device 50a can be realized in which foreign matter is particularly less likely to adhere to the transmitting and receiving surface 10a of the ultrasonic element 10.

[0158] Furthermore, the cross-sectional shape of the second discharge hole 152 shown in Figure 16 (the cross-sectional shape of the plane perpendicular to the Pf axis) is preferably elongated horizontally in the X direction along the reflective surface 13. This allows foreign matter accumulated on the reflective surface 13 to be discharged more efficiently through the second discharge hole 152.

[0159] Furthermore, the placement of the second discharge hole 152 is not limited to the above-mentioned position, but is acceptable as long as it is in a position that allows foreign matter that has entered the waveguide 14 to be discharged. In the third embodiment described above, the same effects as in the second embodiment can be obtained.

[0160] 4. Fourth Embodiment Next, an ultrasonic device according to the fourth embodiment will be described. Figure 17 is a side cross-sectional view showing the configuration of the ultrasonic device 50a according to the fourth embodiment.

[0161] The fourth embodiment will be described below, focusing on the differences from the first embodiment, and similar matters will be omitted from the description. In Figure 17, components identical to those in the first embodiment are denoted by the same reference numerals.

[0162] The ultrasonic device 50a shown in Figure 17 is the same as the ultrasonic device 50a shown in Figure 5, except that a protective member 17 is added. The configuration of the ultrasonic device 50a, described later, is also applicable to the ultrasonic device 50b.

[0163] The ultrasonic device 50a shown in Figure 17 has a mesh-like protective member 17 provided in the opening 12.

[0164] Figure 18 is a perspective view of the protective member 17 shown in Figure 17. The protective member 17 shown in Figure 18 is attached to the support frame 16. The support frame 16 is a resin frame with a rectangular outer shape and has a rectangular opening 16b. The opening 16b is set to be slightly larger than the opening 12. The protective member 17 is attached to the opening 16b of the support frame 16. Notch holes 16a for screw fastening are provided on both short sides of the support frame 16. These notch holes 16a can be used as screw holes to fix the support frame 16 to the opening 12. In this way, the protective member 17 can be attached so as to close the opening 12.

[0165] The protective member 17 is a filter configured in a mesh-like manner, for example, by arranging wires in an intersecting pattern. Examples of wires include resin materials such as polyester, and metal materials such as copper, iron, brass, and stainless steel.

[0166] Furthermore, since the ultrasonic device 50a is equipped with a first discharge hole 151, even if fine foreign matter passes through the protective member 17 and enters the waveguide 14, it can be easily cleaned. Therefore, the protective member 17 is required to have a function to prevent the entry of larger foreign matter. For this reason, the protective member 17 preferably uses a filter with a large mesh opening such that foreign matter does not easily adhere to it even when cleaned with cleaning solution. In the fourth embodiment described above, the same effects as in the second embodiment can be obtained.

[0167] 5. Effects of the above embodiment As described above, the ultrasonic devices 50a and 50b according to the embodiment include an ultrasonic element 10 and a housing 11. The ultrasonic element 10 has an ultrasonic transmitting and receiving surface 10a that performs at least one of transmitting and receiving ultrasonic waves. The housing 11 houses the ultrasonic element 10. The housing 11 also has a reflective surface 13, a waveguide 14, and an opening 12. The reflective surface 13 reflects ultrasonic waves. The waveguide 14 propagates ultrasonic waves. The opening 12 is provided at one end of the waveguide 14, through which ultrasonic waves pass. The length L of the waveguide 14 is longer than the width D of the waveguide 14.

[0168] With this configuration, foreign matter is less likely to adhere to the ultrasonic transmitting and receiving surface 10a, and an ultrasonic device 50a capable of transmitting ultrasonic waves at high sound pressure or an ultrasonic device 50b capable of receiving ultrasonic waves with high sensitivity can be realized.

[0169] In the ultrasonic devices 50a and 50b according to the above embodiment, it is preferable that the following equation (6) is satisfied when the length of the waveguide 14 is L, the propagation angle of the ultrasonic waves propagating through the waveguide 14 is α, and the wavelength of the ultrasonic waves is λ.

[0170]

number

[0171] This configuration significantly increases the probability of constructive interference occurring at the aperture 12. This makes it possible to realize an ultrasonic device 50a capable of transmitting ultrasound at a higher sound pressure, or an ultrasonic device 50b capable of receiving ultrasound with higher sensitivity.

[0172] In the ultrasonic devices 50a and 50b according to the above embodiment, it is preferable that the width D of the waveguide 14 is 1 / 5 or less of the length L of the waveguide 14.

[0173] With this configuration, the propagation angle α falls within an appropriate range, making it possible to realize an ultrasonic device 50a capable of transmitting ultrasonic waves with high sound pressure near the aperture 12, or an ultrasonic device 50b capable of receiving ultrasonic waves with high sensitivity.

[0174] In the ultrasonic devices 50a and 50b according to the above embodiment, it is preferable that the reflective surface 13 is located on the central axis 65a (perpendicular to the transmitting / receiving surface 10a).

[0175] With this configuration, the probability of the ultrasonic waves emitted from the ultrasonic element 10 being reflected by the reflective surface 13 and emitted from the opening 12 can be increased.

[0176] In the ultrasonic devices 50a and 50b according to the above embodiment, the reflective surface 13 is located in the middle of the waveguide 14. The waveguide 14 has a first portion 141 and a second portion 142. The first portion 141 extends from the ultrasonic element 10 to the reflective surface 13 along the central axis 65a (perpendicular to the transmitting / receiving surface 10a). The second portion 142 extends from the reflective surface 13 to the opening 12 along the central axis 65b (perpendicular to the opening 12). Preferably, the length of the first portion 141 in the direction of extension of the central axis 65a is longer than the width of the first portion 141. Preferably, the length of the second portion 142 in the direction of extension of the central axis 65b is longer than the width of the second portion 142.

[0177] With this configuration, ultrasonic attenuation is more easily suppressed in both the first part 141 and the second part 142. Therefore, an ultrasonic device 50a capable of transmitting ultrasonic waves at a higher sound pressure, or an ultrasonic device 50b capable of receiving ultrasonic waves with higher sensitivity, can be realized.

[0178] In the ultrasonic devices 50a and 50b according to the above embodiment, it is preferable that the normal 61 of the reflective surface 13 is inclined with respect to both the central axis 65a (perpendicular to the transmitting / receiving surface 10a) and the central axis 65b (perpendicular to the opening 12).

[0179] With this configuration, the probability of the ultrasonic waves emitted from the ultrasonic element 10 shown in Figure 5 being reflected by the reflective surface 13 and emitted from the opening 12 can be increased. In addition, the probability of the ultrasonic waves reflected by the reflective surface 13 returning to the ultrasonic element 10 can be reduced. As a result, the sound pressure of the ultrasonic waves emitted from the opening 12 can be sufficiently increased.

[0180] In the ultrasonic devices 50a and 50b according to the above embodiment, it is preferable that the central axis 65a (perpendicular to the transmitting / receiving surface 10a) and the central axis 65b (perpendicular to the opening 12) are inclined in opposite directions via the normal 61 of the reflecting surface 13.

[0181] With this configuration, the ultrasonic waves emitted from the ultrasonic element 10 shown in Figure 5 can be reflected by the reflective surface 13 and then emitted from the opening 12 while suppressing the attenuation of the ultrasonic waves.

[0182] In the ultrasonic devices 50a and 50b according to the above embodiment, it is preferable that the central axis 65a (perpendicular to the transmitting / receiving surface 10a) and the central axis 65b (perpendicular to the opening 12) intersect each other on the reflecting surface 13.

[0183] With this configuration, for example, when ultrasonic waves propagating along the central axis 65a are reflected by the reflective surface 13, the reflection efficiency can be sufficiently increased.

[0184] In the ultrasonic devices 50a and 50b according to the above embodiment, it is preferable that the central axis 65b (perpendicular to the opening 12) is inclined with respect to the original document P (object to be irradiated) onto which the ultrasonic waves are irradiated.

[0185] With this configuration, multiple reflections of ultrasound between the original document P and the ultrasound devices 50a and 50b can be suppressed.

[0186] In the ultrasonic devices 50a and 50b according to the above embodiment, the housing 11 may have a first discharge hole 151 provided at a different position from the opening 12.

[0187] This configuration offers the advantage of easily discharging foreign matter through the first discharge hole 151.

[0188] In the ultrasonic devices 50a and 50b according to the above embodiment, the housing 11 may have a second discharge hole 152 provided at a different position from the opening 12 and the first discharge hole 151.

[0189] This configuration offers the advantage of making it easier to discharge foreign matter through the first discharge hole 151 or the second discharge hole 152.

[0190] The ultrasonic devices 50a and 50b according to the above embodiment may have a mesh-like protective member 17 provided in the opening 12. With this configuration, the protective member 17 can prevent large foreign objects from entering.

[0191] The double-feed detection device 58 according to the above embodiment is an ultrasonic device 50a according to the above embodiment, comprising a transmitting ultrasonic device whose transmitting / receiving surface 10a transmits ultrasonic waves, and an ultrasonic device 50b according to the above embodiment, whose transmitting / receiving surface 10a receives ultrasonic waves. The transmitting ultrasonic device and the receiving ultrasonic device are arranged on either side of the document transport path (the transport path of the document P (medium)). The transmitting ultrasonic device transmits ultrasonic waves, and the receiving ultrasonic device receives the ultrasonic waves that have passed through the document P, and a double-feed of the document P is detected based on the strength of the received signal.

[0192] With this configuration, a double-feed detection device 58 is obtained in which foreign matter is less likely to adhere to the ultrasonic transmitting and receiving surface 10a of the ultrasonic devices 50a and 50b, maintenance is easy, and the accuracy of double-feed detection is high.

[0193] The transport device 59 according to the above embodiment includes a double-feed detection device 58 according to the above embodiment and transports the document P along the document transport path (transport path of the document P (medium)).

[0194] This configuration makes it possible to realize a conveying device 95 that is easy to maintain and has high accuracy in detecting double feeding.

[0195] The scanner 100 according to the above embodiment comprises a transport device 95 according to the above embodiment and a reading unit (first reading unit 32 and second reading unit 33) that reads an image attached to an original document P (medium).

[0196] This configuration makes it possible to realize a scanner 100 that is easy to maintain, has high accuracy in detecting double feeds, and is easy to handle.

[0197] The ultrasonic device, double-feed detection device, transport device, and scanner of the present invention have been described above based on the illustrated embodiments, but the present invention is not limited thereto. For example, the ultrasonic device, double-feed detection device, transport device, and scanner of the present invention may be configured such that each part of the embodiment is replaced with any component having a similar function, or any component may be added to the embodiment.

[0198] Furthermore, the ultrasonic device of the present invention can be applied to electronic devices other than scanners. For example, in a printing device (printer) equipped with a print head that prints an image on paper being transported along a transport path, a double-feed detection device using the ultrasonic device of the present invention may be applied to detect double feeding of the medium. Even with this configuration, the same effects as those of the above embodiments can be obtained. [Explanation of Symbols]

[0199] 1...Semiconductor substrate, 1a...Opening, 1b...Partition, 2...Diaphragm, 2a...Part, 3...Element substrate, 4...First electrode, 5...Piezoelectric element, 6...Second electrode, 7...Vibrating part, 8...Base substrate, 9...Main substrate, 9a...Notch, 10...Ultrasonic element, 10a...Transmitting / receiving surface, 11...Housing, 11a...Base, 11b...First wall, 11c...Second wall, 11d...Third wall, 12...Opening, 13...Reflecting surface, 14...Waveguide, 16...Support frame, 16a...Notch, 16b...Opening, 17...Protective member, 20...First roller pair, 20a...Roller, 20b...Roller, 21...Second roller Pair, 21a...Roller, 21b...Roller, 22...Third Roller Pair, 22a...Roller, 22b...Roller, 23...Fourth Roller Pair, 23a...Roller, 23b...Roller, 24...Fifth Roller Pair, 24a...Roller, 24b...Roller, 32...First Reading Unit, 33...Second Reading Unit, 34...Pressure Spring, 35...Flap, 41...First Unit, 42...Second Unit, 42b...Front, 43...Third Unit, 47...Transport Motor, 50a...Ultrasonic Device, 50b...Ultrasonic Device, 55...Transmit / Receive Circuit, 58...Double Feed Detection Device, 59...Transport Device, 60... Rotating axis, 61...normal, 65...central axis, 65a...central axis, 65b...central axis, 65c...central axis, 70...main body, 71...stand, 72...locking member, 73...operating unit, 73a...operating button, 73b...operating button, 73c...operating button, 74...upper cover, 74b...support unit, 75...document support unit, 76...cover member, 76a...opening, 77...connector, 80...control unit, 81...calculation unit, 82...transport control unit, 83...reading control unit, 84...double feed detection unit, 85...storage unit, 86...interface unit, 87...external device, 90...mounting surface, 95...transport device, 100...Scanner, 141...First part, 142...Second part, 151...First ejection hole, 152...Second ejection hole, D...Width, FS...Free space, L...Length, L1...Length, L2...Length, M...Model, P...Original document, Pe...Perpendicular direction, Pf...Transport direction, R0...Feed path, R1...Transport path, R2...Reading path, R3...Ejection path, S1...First surface, S2...Second surface, Tr...Ultrasonic transducer, X1...Distance, X2...Distance, d1...Depth, d2...Depth, i1...Interference point, i2...Interference point, r1...Propagation path, r2...Propagation path, w1...Width, w2...Width, α...Propagation angle, θ...Angle

Claims

1. An ultrasonic element having an ultrasonic transmitting and receiving surface that performs at least one of ultrasonic transmission and ultrasonic reception, A housing for the ultrasonic element, Equipped with, The aforementioned enclosure is The reflective surface that reflects the ultrasonic waves, A waveguide for propagating the aforementioned ultrasonic waves, An opening is provided at one end of the waveguide through which the ultrasonic waves pass, It has, An ultrasonic device characterized in that the length of the waveguide is longer than the width of the waveguide.

2. The ultrasonic apparatus according to claim 1, where L is the length of the waveguide, α is the propagation angle of the ultrasonic waves propagating through the waveguide, and λ is the wavelength of the ultrasonic waves, and the following equation is satisfied. [Math 1] [In the above formula, k is an integer.]

3. The ultrasonic apparatus according to claim 1, wherein the width of the waveguide is 1 / 5 or less of the length of the waveguide.

4. The ultrasonic apparatus according to claim 1, wherein the reflective surface is provided on a perpendicular line to the transmitting and receiving surface.

5. The reflective surface is positioned in the middle of the waveguide. The waveguide is, A first portion extending from the ultrasonic element to the reflective surface along the perpendicular line of the transmitting and receiving surface, A second portion extending from the reflective surface to the opening along the perpendicular line of the opening, It has, The length of the first portion in the direction of extension of the perpendicular on the transmitting and receiving surface is longer than the width of the first portion. The ultrasonic apparatus according to claim 1, wherein the length of the second portion in the direction of extension of the perpendicular of the opening is longer than the width of the second portion.

6. The ultrasonic apparatus according to claim 5, wherein the normal of the reflective surface is inclined with respect to both the perpendicular of the transmitting and receiving surface and the perpendicular of the opening.

7. The ultrasonic apparatus according to claim 6, wherein the perpendicular of the transmitting and receiving surface and the perpendicular of the opening are inclined in opposite directions to each other via the normal of the reflecting surface.

8. The ultrasonic apparatus according to claim 7, wherein the perpendicular line of the transmitting and receiving surface and the perpendicular line of the opening intersect each other on the reflecting surface.

9. The ultrasonic device according to claim 5, wherein the perpendicular line of the opening is inclined with respect to the object to be irradiated with the ultrasonic waves.

10. The ultrasonic device according to claim 1, wherein the housing has a first discharge hole provided at a position different from the opening.

11. The ultrasonic apparatus according to claim 10, wherein the housing has a second discharge hole provided at a position different from the opening and the first discharge hole.

12. The ultrasonic device according to claim 10, further comprising a mesh-like protective member provided in the opening.

13. An ultrasonic device according to any one of claims 1 to 12, wherein the transmitting and receiving surface is a transmitting ultrasonic device for transmitting ultrasonic waves, An ultrasonic device according to any one of claims 1 to 12, wherein the transmitting and receiving surface is a receiving ultrasonic device for receiving the ultrasonic waves, Equipped with, The transmitting ultrasonic device and the receiving ultrasonic device are arranged on either side of the medium transport path. A double-feed detection device characterized by transmitting ultrasonic waves from the transmitting ultrasonic device, receiving the ultrasonic waves that have passed through the medium with the receiving ultrasonic device, and detecting double-feeding of the medium based on the intensity of the received signal.

14. A conveying device comprising the double-feed detection device described in claim 13, and characterized in that it conveys the medium along the conveying path of the medium.

15. The conveying device according to claim 14, A reading unit that reads an image attached to the aforementioned medium, A scanner characterized by having the following features.

Images