JP7147534B2 - ultrasonic device - Google Patents

Description

The present invention relates to ultrasound devices.

2. Description of the Related Art Conventionally, there has been known a device that detects the state of an object using ultrasonic waves (see, for example, Patent Document 1).
The apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200003 has a multi-feeding sensor that detects multi-feeding of sheets conveyed by a sheet conveying device. This double feed sensor includes a transmitter sensor unit that transmits ultrasonic waves so as to pass through the sheets, and a receiver sensor unit that receives the ultrasonic waves that have passed through the sheets. The double feed sensor described in Patent Document 1 is provided with a cover member for protecting the circuit board to which the sender sensor unit is fixed.

JP 2016-159986 A

However, the multi-feed sensor described in Patent Document 1 cannot protect the ultrasonic transmission/reception surface of the multi-feed sensor. For example, when a paper medium or the like is used as a sheet, foreign matter such as paper dust may be generated. If such foreign matter accumulates on the ultrasonic transmission/reception surface of the double feed sensor, there is a problem that the transmission sensitivity and reception sensitivity of ultrasonic waves are lowered.

An ultrasonic device according to a first application example performs at least one of transmitting ultrasonic waves along a first axis and receiving ultrasonic waves input along the first axis. and a protective member provided on the first axis and covering the ultrasonic element, wherein the protective member has a plurality of holes for passing the ultrasonic waves traveling along the first axis. characterized by having

In the ultrasonic device according to this application example, the shield portion is configured to have a substantially cylindrical shape with the first axis as the central axis, and the ultrasonic element is arranged so as to be surrounded by the inner circumferential surface of the cylinder of the shield portion. , the shield portion extends along the first axis from a position surrounding the ultrasonic element, and has a passage hole for allowing the ultrasonic wave to pass through at the extending tip portion, and the protective member is provided in the shield portion. It is preferable that it is provided so as to cover the passage hole.

In the ultrasonic device of this application example, it is preferable that a sound absorbing portion surrounding the passage hole is provided on a surface of the extending distal end portion of the shield portion opposite to the ultrasonic element.

In the ultrasonic device of this application example, the plurality of wires are arranged along a first direction intersecting the first axis and a second direction intersecting the first axis and the first direction. A normal line of a plane including the first direction and the second direction is preferably inclined with respect to the first axis.

In the ultrasonic device of this application example, it is preferable that a normal line of a plane including the first direction and the second direction is inclined at an angle of 5° or more with respect to the first axis.

In the ultrasonic device of this application example, the ultrasonic element performs at least one of transmitting the ultrasonic waves toward the object and receiving the ultrasonic waves input from the object, The first axis is inclined at a first angle with respect to a normal to the object, and a normal to a plane containing the first direction and the second direction is inclined with respect to a normal to the object in the It is preferably slanted at a second angle different from the first angle.

In the ultrasonic device of this application example, the ultrasonic element has a first surface on which the ultrasonic waves are transmitted or received and a second surface opposite to the first surface, and the ultrasonic element is The pedestal has a third surface perpendicular to the first axis, to which the second surface of the ultrasonic element is bonded, and a fourth surface provided on the opposite side of the third surface. It is preferable that the normal to the fourth surface is inclined with respect to the first axis.

In the ultrasonic device of this application example, it is preferable that the normal to the fourth surface is inclined at an angle of 5° or more with respect to the first axis.

In the ultrasonic device of this application example, a pair of the ultrasonic elements is provided, one of the pair of ultrasonic elements is a transmission section that transmits the ultrasonic waves, and the other of the pair of ultrasonic elements is: It is preferable that the transmitting section and the receiving section are provided at positions facing each other on the first axis.

In the ultrasonic device according to this application example, the ultrasonic element receives the ultrasonic waves from the target object, outputs a received signal, and detects the state of the target object based on the received signal. is preferably provided.

1 is an external view showing a schematic configuration of an image scanner according to a first embodiment; FIG. FIG. 2 is a side cross-sectional view schematically showing a conveying section of the image scanner of the present embodiment; 1 is a cross-sectional view showing a schematic configuration of an ultrasonic sensor according to this embodiment; FIG. FIG. 2 is a schematic cross-sectional view of part of the transmission main body of the embodiment; The figure which shows schematic structure of the protection member of this embodiment. FIG. 10 is a diagram showing changes in the voltage value of the received signal when the distance from the transmitter to the protective member is changed in a plurality of patterns in which the angle of the normal to the protective member with respect to the central axis of the sensor is different; FIG. 10 is a diagram showing waveforms of received signals when ultrasonic waves are transmitted from the transmission unit when the protection member is arranged perpendicular to the central axis of the sensor and paper is not arranged; 8 is a diagram showing changes in the signal D2 in FIG. 7 when the angle between the normal to the protective member and the center axis of the sensor is changed; FIG. A diagram for explaining the dimensions of the protection member and the receiver main body of the present embodiment. FIG. 2 is a block diagram showing the control configuration of the image scanner of this embodiment; Sectional drawing which shows schematic structure of the ultrasonic sensor in 2nd embodiment. FIG. 10 is a diagram showing changes in received signals when the distance from the protective member on the transmitting section side to the paper is changed when the sound absorbing section and the protective member are not provided in the shield section. FIG. 10 is a diagram showing changes in received signals when the distance from the protective member on the transmitting section side to the paper is changed when the sound absorbing section is provided in the shield section without providing the protective member. Sectional drawing which shows schematic structure of the ultrasonic sensor in 3rd embodiment. FIG. 11 is a diagram showing received signals when the distance from the protective member on the transmission unit side to the paper is changed in the second embodiment; FIG. 11 is a diagram showing received signals when the distance from the protective member on the transmission unit side to the paper is changed in the third embodiment; FIG. 5 is a cross-sectional view showing a schematic configuration of an ultrasonic sensor according to Modification 1; FIG. 5 is a cross-sectional view showing a schematic configuration of an ultrasonic sensor according to Modification 2; FIG. 11 is a cross-sectional view showing a schematic configuration of an ultrasonic sensor according to Modification 3; FIG. 11 is a cross-sectional view showing a schematic configuration of an ultrasonic sensor according to Modification 3; FIG. 11 is a plan view showing a configuration example of a protection member according to Modification 4; FIG. 12 is a plan view showing another configuration example of the protection member according to Modification 4; FIG. 12 is a plan view showing another configuration example of the protection member according to Modification 4; FIG. 12 is a plan view showing another configuration example of the protection member according to Modification 4; FIG. 12 is a plan view showing another configuration example of the protection member according to Modification 4; FIG. 11 is a cross-sectional view showing the configuration of a transmission unit according to Modification 5; FIG. 11 is a perspective view showing the configuration of a transmission pedestal according to Modification 5; FIG. 11 is a plan view showing the configuration of a transmission pedestal according to Modification 5; FIG. 11 is a schematic diagram showing another example of the inclined end face of the transmission base portion of Modification 5; FIG. 11 is a schematic diagram showing another example of the inclined end face of the transmission base portion of Modification 5;

[First embodiment]
A first embodiment will be described below.
FIG. 1 is an external view showing a schematic configuration of an image scanner 10 of this embodiment. FIG. 2 is a side cross-sectional view showing an outline of the conveying section of the image scanner 10. As shown in FIG. Note that FIG. 2 is a side cross-sectional view of the image scanner 10 when viewed from the main scanning direction (X direction) orthogonal to the transport direction (Y direction).

[Schematic Configuration of Image Scanner 10]
The image scanner 10 is an example of electronic equipment, and as shown in FIG. As shown in FIG. 2, inside the apparatus main body 11 are a transport unit 13 that transports the paper P, a scanning unit 14 that reads the image of the transported paper P, and an ultrasonic sensor that detects double feeding of the paper P. 15 and a control unit 16 for controlling the image scanner 10 are provided. In this embodiment, an example in which the ultrasonic sensor 15 detects multi-feeding of the sheets P with the sheet P as the object is shown, but the present invention is not limited to this. As the object, for example, various media such as films and fabrics can be used.

As shown in FIGS. 1 and 2, the apparatus main body 11 is provided with a feed port 11A at a connection position with the sheet support 12. As shown in FIG. The sheets P placed on the sheet support 12 are fed one by one to the feed port 11A. The fed sheet P is transported along a predetermined transport path 130 in the apparatus main body 11 by the transport unit 13 . After the image is read by the scanning unit 14 at the reading position in the middle of the transportation, the sheet is ejected from the ejection port 11B opened at the lower front side of the apparatus main body 11 .

[Configuration of Conveyor 13]
The transport unit 13 transports a plurality of sheets of paper P set on the paper support 12 one by one in the transport direction (Y direction). That is, the transport unit 13 guides and feeds the paper P fed from the feed port 11A into the apparatus main body 11 and transports the fed paper P along the predetermined transport path 130 .

More specifically, the transport unit 13 includes a first feed roller pair 131 arranged on the upstream side (−Y side) of the transport path 130 in the Y direction, and and a second feeding roller pair 132 arranged on the downstream side (+Y side). Further, the transport unit 13 includes a first transport roller pair 133 arranged on the -Y side and a second transport roller pair 134 arranged on the +Y side with the paper P reading position interposed therebetween.

The first feeding roller pair 131 is composed of a first drive roller 131A and a first driven roller 131B. Similarly, the second feed roller pair 132 is composed of a second drive roller 132A and a second driven roller 132B. Also, the first conveying roller pair 133 is composed of a third driving roller 133A and a third driven roller 133B. Similarly, the second transport roller pair 134 is composed of a fourth driving roller 134A and a fourth driven roller 134B. Each of the driven rollers 131B to 134B is driven (rotated together) by the rotation of the paired drive rollers 131A to 134A.

The drive rollers 131A to 134A constituting the roller pairs 131 to 134 are rotationally driven by the power of a transport motor 135, which is their power source. The transport motor 135 is controlled by the controller 16 to drive the drive rollers 131A to 134A.
Further, the second driven roller 132B constituting the second feeding roller pair 132 is a retard roller, and the friction coefficient of the outer peripheral surface of the second driven roller 132B with respect to the paper P is the same as the friction coefficient of the outer peripheral surface of the second driving roller 132A with respect to the paper P. is larger than Therefore, the second feeding roller pair 132 functions as a separation mechanism that separates the sheets of paper P one by one and feeds them to the +Y side. Therefore, the plurality of sheets P stacked on the sheet support 12 by the rotation of the first feeding roller pair 131 are fed one by one from the feeding port 11A into the apparatus main body 11 in order from the top sheet, for example. Further, the sheets are separated one by one by the rotation of the second feeding roller pair 132 and fed to the +Y side.

[Configuration of scanning unit 14]
As shown in FIG. 2, between the first transport roller pair 133 and the second transport roller pair 134 of the transport path 130, a reading position for reading the image of the paper P is provided, and the scanning unit 14 is provided. there is
The scanning unit 14 is composed of a first scanning unit 14A and a second scanning unit 14B provided on both sides of the transport path 130 . The scanning unit 14 is composed of a light source 141 capable of irradiating the sheet P being conveyed with light, and an image sensor 142 extending in the main scanning direction (X direction). In the normal reading mode for reading the front surface of the paper P, the first scanning unit 14A performs the reading operation. perform a read operation together. The light source 141 and the image sensor 142 constituting the first scanning section 14A and the second scanning section 14B are connected to the control section 16, and perform scanning processing for reading an image of the paper P under the control of the control section 16. FIG.

[Configuration of Ultrasonic Sensor 15]
The ultrasonic sensor 15 is provided at a position between the second feed roller pair 132 and the first transport roller pair 133 on the transport path 130 . The ultrasonic sensor 15 is a multi-feeding sensor and detects multi-feeding of the sheets P transported by the transport unit 13 .

FIG. 3 is a cross-sectional view showing a schematic configuration of the ultrasonic sensor 15. As shown in FIG. Note that FIG. 3 shows a cross-sectional view of the ultrasonic sensor 15 when viewed from the Y direction.
The ultrasonic sensor 15 is configured with a pair of ultrasonic elements. One of the pair of ultrasonic elements is the transmitter 151 and transmits ultrasonic waves. The other of the pair of ultrasonic elements is a receiving section 152 for receiving ultrasonic waves.
As shown in FIG. 3, the transmitting unit 151 and the receiving unit 152 face each other on the center axis 15C (first axis) of the sensor, and are arranged across the transport path 130 along which the paper P is transported. there is
In the ultrasonic sensor 15 , ultrasonic waves are transmitted from the transmission section 151 to the sheet P transported along the transport path 130 by the transport section 13 . The ultrasonic waves transmitted from the transmitting unit 151 are input to the paper P, and the ultrasonic waves transmitted through the paper P are received by the receiving unit 152 . When the receiving unit 152 receives the ultrasonic waves, a received signal corresponding to the sound pressure of the received ultrasonic waves is output from the receiving unit 152, and double feeding of the paper P is detected based on the signal strength of the received signal. .

As shown in FIG. 3, the sensor center axis 15C is an axis that passes through the center of the transmitter 151 and the center of the receiver 152, and is the transmission/reception direction of ultrasonic waves. In this embodiment, the sensor central axis 15C is inclined at the first angle θ with respect to the normal line of the surface of the paper P transported on the transport path 130 .
If the sensor central axis 15C coincides with the normal direction of the surface of the paper P, the ultrasonic waves transmitted from the transmission unit 151 may be multiple-reflected between the paper P and the transmission unit 151 . Further, there is a possibility that the ultrasonic waves passing through the paper P may be multiple-reflected between the receiving unit 152 and the paper P. FIG. In this case, in the receiving unit 152, in addition to the ultrasonic waves that pass through the paper P from the transmitting unit 151 and are received by the receiving unit 152, the ultrasonic waves that are multiple-reflected between the paper P and the transmitting unit 151 are received. Ultrasonic waves multiple-reflected between the portion 152 and the paper P are received by the receiving portion 152, and accurate double feeding cannot be detected.
On the other hand, by inclining the sensor center axis 15C with respect to the normal line of the surface of the paper P, it is possible to reduce the reception of unnecessary ultrasonic wave components such as multiple reflected ultrasonic waves, resulting in highly accurate double feed detection. becomes possible.

In addition, the transmitting section 151 and the receiving section 152 are each provided with a shield section 153 and a protection member 154 . The shield part 153 and the protection member 154 are members for protecting the transmission part 151 and the reception part 152, which are ultrasonic elements. A detailed description of the shield part 153 and the protective member 154 will be given later.

[Configuration of transmitting unit 151 and receiving unit 152]
The transmission section 151 includes a transmission base section 151A and a transmission main body section 151B, and is attached to the transmission circuit board 31 . The transmission circuit board 31 is fixed in the apparatus body 11 so as to be parallel to the transport path 130 .
A base end surface 151A1 (fourth surface) of the transmission base portion 151A is fixed to the transmission circuit board 31, and a tip end surface 151A2 (third surface) opposite to the base end surface 151A1 is fixed to the base end surface. It inclines at the first angle θ with respect to the end surface 151A1. Then, by fixing the transmission body portion 151B to the distal end surface 151A2, the ultrasonic transmission surface 151C of the transmission unit 151 is fixed at an angle orthogonal to the sensor center axis 15C. Here, the transmission surface 151C of the transmission body portion 151B corresponds to the first surface from which ultrasonic waves are transmitted, and the surface of the transmission body portion 151B on the side fixed to the transmission base portion 151A (transmission side fixing surface 151B1) is , corresponds to the second surface opposite to the first surface. A transmission-side fixing surface 151B1 of the transmission main body 151B is joined to a tip-end-side end surface 151A2, which is the third surface, with an adhesive, double-sided tape, or the like.
The transmission main body 151B is an ultrasonic element that transmits ultrasonic waves along the sensor central axis 15C. A detailed configuration of the transmission main unit 151B will be described later.

The receiving section 152 has substantially the same configuration as the transmitting section 151 . That is, the receiver 152 includes a receiver pedestal 152A and a receiver main body 152B, and is fixed to the receiver circuit board 32 . The receiving circuit board 32 is fixed parallel to the transport path 130 within the apparatus main body 11 .
The base end face 152A1 of the receiver seat portion 152A is fixed to the receiver circuit board 32, and the tip end face 152A2 opposite to the base end face 152A1 is at a first angle θ with respect to the base end face 152A1. incline. By fixing the receiving main body portion 152B to the tip side end surface 152A2, the ultrasonic wave receiving surface 152C of the receiving portion 152 is fixed at an angle orthogonal to the sensor central axis 15C. Here, the receiving surface 152C of the main receiving unit 152B corresponds to the first surface on which ultrasonic waves are received, and the surface of the main receiving unit 152B on the side fixed to the receiving pedestal 152A (receiving side fixing surface 152B1) is , corresponds to the second surface opposite to the first surface. The receiving fixing surface 152B1 of the receiving body 152B is joined to the tip side end surface 152A2, which is the third surface, with an adhesive, double-sided tape, or the like.
The receiving body 152B is an ultrasonic element that receives ultrasonic waves input along the sensor central axis 15C.

In this embodiment, an example in which the transmission circuit board 31 and the reception circuit board 32 are provided independently is shown, but the present invention is not limited to this, and the transmission circuit board 31 and the reception circuit board 32 are integrated into one board. It is good also as a structure provided in. Also, at least one of the transmission circuit board 31 and the reception circuit board 32 may be composed of a plurality of boards.

[Detailed configuration of transmission main unit 151B]
Next, the configuration of the transmission main unit 151B will be described more specifically. Note that the receiving main unit 152B has the same configuration as the transmitting main unit 151B. Therefore, the detailed configuration of the reception main unit 152B is omitted.

FIG. 4 is a cross-sectional view of part of the transmission body 151B.
As shown in FIG. 4, the transmitter main body 151B includes an element substrate 21 and a piezoelectric element 22. As shown in FIG.
The element substrate 21 includes a substrate body portion 211 and a diaphragm 212 provided on one surface side of the substrate body portion 211 . Here, in the following description, the substrate thickness direction of the element substrate 21 is defined as the Z direction. The Z direction is the direction in which ultrasonic waves are transmitted, and is parallel to the sensor central axis 15C.
The substrate main body 211 is a substrate that supports the diaphragm 212 and is made of a semiconductor substrate such as Si. The substrate main body 211 is provided with an opening 211A penetrating through the substrate main body 211 along the Z direction.

The vibration plate 212 is made of SiO ₂ , a laminate of SiO ₂ and ZrO ₂ , or the like, and is provided on the −Z side of the substrate main body 211 . The diaphragm 212 is supported by the partition wall 211B of the substrate main body 211 forming the opening 211A, and closes the -Z side of the opening 211A. A portion of the diaphragm 212 that overlaps with the opening 211A when viewed in the Z direction constitutes a vibrating portion 212A.

The piezoelectric element 22 is provided on the diaphragm 212 at a position overlapping each vibrating portion 212A when viewed from the Z direction. As shown in FIG. 4, the piezoelectric element 22 is constructed by stacking a first electrode 221, a piezoelectric film 222, and a second electrode 223 on a diaphragm 212 in this order.

Here, one ultrasonic transducer Tr is configured by one vibrating portion 212A and the piezoelectric element 22 provided on the vibrating portion 212A. Although illustration is omitted, in the present embodiment, the transmission body 151B is configured by arranging such ultrasonic transducers Tr in a two-dimensional array structure.

The piezoelectric film 222 of the transmission body 151B expands and contracts when a pulse wave voltage having a predetermined frequency is applied between the first electrode 221 and the second electrode 223 of each ultrasonic transducer Tr. As a result, the vibrating section 212A vibrates at a frequency corresponding to the opening width of the opening 211A, and ultrasonic waves are transmitted from the vibrating section 212A toward the +Z side along the sensor central axis 15C. That is, the surface of the element substrate 21 on the +Z side becomes the ultrasonic transmission surface 151</b>C of the transmission unit 151 .

As described above, the reception body section 152B has the same configuration as the transmission body section 151B, and has a configuration in which the transmission body section 151B shown in FIG. 4 is turned upside down. That is, in the receiver main body section 152B, the diaphragm 212 is arranged on the +Z side of the substrate main body section 211, and the piezoelectric element 22 is arranged on the +Z side of the diaphragm 212. FIG. Therefore, in the receiving body 152B, the −Z side surface of the element substrate 21 on which the diaphragm 212 is not provided becomes the receiving surface 152C, and receives the ultrasonic waves input from the −Z side toward the +Z side. When ultrasonic waves are input from the opening 211A along the sensor central axis 15C, the vibrating portion 212A of the receiving main body 152B vibrates. As a result, a potential difference is generated between the first electrode 221 side and the second electrode 223 side of the piezoelectric film 222, and a reception signal corresponding to the potential difference is output from the reception body 152B.

[Configuration of Shield Part 153 and Protection Member 154]
The shield section 153 is provided for each of the transmission section 151 and the reception section 152, as shown in FIG. The shield part 153 is made of a conductive material such as metal, and protects the transmitter body part 151B and the receiver body part 152B from static electricity and electromagnetic waves.
The shield part 153 has a substantially cylindrical shield wall 153A with the center axis of the sensor center axis 15C, and is fixed to the circuit board at the base end side and extends toward the transport path 130 side.
That is, the shield part 153 provided on the transmission part 151 side is fixed to the transmission circuit board 31 at the base end side, and extends toward the transport path 130 side (paper P side) with the sensor central axis 15C as the central axis. Therefore, the transmission base portion 151A and the transmission main body portion 151B are arranged so as to be surrounded by the cylindrical inner circumferential surface of the cylindrical shield wall 153A of the shield portion 153 .
Similarly, the shield part 153 provided on the receiving part 152 side is fixed to the receiving circuit board 32 at the base end side, and extends toward the transport path 130 side (paper P side) with the sensor central axis 15C as the central axis. Therefore, the receiver base portion 152A and the receiver main body portion 152B are arranged so as to be surrounded by the cylindrical inner peripheral surface of the cylindrical shield wall 153A of the shield portion 153 .

Further, the shield part 153 has a protruding part 153B protruding from the shield wall 153A toward the sensor central axis 15C at the end of the shield wall 153A on the transport path 130 side. The protruding portion 153B is provided with a passage hole 153C through which ultrasonic waves pass, at a position intersecting with the sensor central axis 15C. In other words, the shield part 153 on the side of the transmitting part 151 extends from a position surrounding the transmitting base part 151A and the transmitting main body part 151B to the side close to the transport path 130 along which the paper P is transported, and the extending tip part is the transmitting main body part. It has a passage hole 153C through which the ultrasonic wave transmitted from 151B passes. Further, the shield part 153 on the side of the receiving part 152 extends from a position surrounding the receiving base part 152A and the receiving body part 152B to the side close to the transport path 130 along which the paper P is transported. It has a passage hole 153C through which an ultrasonic wave to be received by 152B passes.
In this embodiment, as shown in FIG. 3, the projecting portion 153B is configured in a plate shape parallel to the transport path 130. As shown in FIG. That is, the normal to the projecting portion 153B is inclined at the first angle θ with respect to the sensor central axis 15C.
A protection member 154 is provided on the projecting portion 153B of the shield portion 153 so as to cover the passage hole 153C.

FIG. 5 is a diagram showing a schematic configuration of the protection member 154 of this embodiment. In FIG. 5, the Xm direction (first direction) and the Ym direction (second direction) are directions that intersect with the sensor center axis 15C, and the normal line of the XmYm plane is at the first angle with respect to the sensor center axis 15C. Tilt at θ. In the following description, the normal to the XmYm plane may be referred to as the normal to the protective member 154. FIG.
The protective member 154 is configured in a mesh shape by arranging a plurality of wire rods 154A having a wire direction in the Xm direction along the Ym direction and arranging a plurality of wire rods 154A having a wire direction in the Ym direction along the Xm direction. It is a filtered filter. Although FIG. 5 shows an example in which the Xm direction and the Ym direction intersect at 90°, the present invention is not limited to this, and the angle formed by the Xm direction and the Ym direction may be an angle other than 90°.
As the material of the wire rod 154A, metal materials such as copper, iron, brass, and SUS, alloy materials, and synthetic resins such as nylon and polyester can be used. In particular, it is preferable to use a material having conductivity, and in this case, resistance to static electricity and electromagnetic waves can be obtained.

Also, the wire diameter W1 of the wire rod 154A is preferably _less than the wavelength of the ultrasonic wave. As a result, the problem that the ultrasonic waves are irregularly reflected by the wire rod 154A of the protective member 154 is suppressed.

In such a protective member 154, a gap 154B is formed between a pair of wire rods 154A adjacent in the Xm direction and a pair of wire rods 154A adjacent in the Ym direction. In addition, the gap 154B corresponds to a hole through which the ultrasonic wave traveling along the sensor central axis 15C passes from the transmitting section 151 side to the receiving section 152 side. In the present embodiment, in order to suppress adhesion and accumulation of foreign matter such as paper dust on the transmitting surface 151C and the receiving surface 152C, the width of the gap 154B, that is, the distance between the adjacent wires 154A (opening W ₂ ) is It is preferable to make it 1 mm or less.

Also, the distance between the central axes of the wires 154A is defined as a pitch W3 _, and the porosity S is defined by the following (1).
S=100×(W ₂ /W ₃ ) ² (1)
In this embodiment, the porosity S is preferably 20% or more.
When the ultrasonic sensor 15 detects the multi-feeding of the paper P, it is determined whether or not the ultrasonic wave transmitted through the paper P is detected by the main receiving unit 152B. In other words, the ultrasonic waves transmitted from the transmitter body 151B need to be transmitted through the protective member 154 of the transmitter 151, the paper P, and the protective member 154 of the receiver 152 and input to the receiver body 152B. In this case, it is preferable that the sound transmittance of each protective member 154 is 50% or more in order to suppress the sound pressure drop of the ultrasonic waves received by the receiving body 152B.
Here, when the porosity S is less than 20%, the sound transmittance is less than 50%. Therefore, even when the paper P is not multi-fed in the transport path 130, the sound pressure of the ultrasonic waves received by the main receiving portion 152B is low, and the received signal is small. In this case, it becomes difficult to distinguish between the received signal and noise, and double feeding cannot be detected accurately.
On the other hand, when the porosity S is 20% or more, the sound transmittance is 50% or more. It is possible to detect double feeding by the sound wave sensor 15 .

In this embodiment, the protective member 154 as described above is provided so as to cover the passage hole 153C of the shield portion 153 . The protective member 154 is adhered and fixed to the ultrasonic element-side surface of the projecting portion 153B of the shield portion 153 with an adhesive or the like. In other words, when the paper P is conveyed to the position of the ultrasonic sensor 15, the protective member 154 is arranged between the transmission unit 151 and the paper P and between the reception unit 152 and the paper P.
As described above, the normal line of the projecting portion 153B of the shield portion 153 is inclined at the first angle θ with respect to the sensor central axis 15C. Therefore, the normal to the protective member 154 fixed to the projecting portion 153B, that is, the normal to the XmYm plane is also inclined at the first angle θ with respect to the sensor center axis 15C.

[Configuration for Suppressing Multiple Reflection of Ultrasonic Waves]
FIG. 6 shows a plurality of patterns in which the angles of the normal to the protective member 154 with respect to the sensor central axis 15C are different, and the distance L1 from the transmitting surface 151C of the transmitting section 151 to the protective member 154 _on the sensor central axis 15C is changed. FIG. 10 is a diagram showing changes in the voltage value of a received signal when In FIG. 6, the angle between the normal line of the protective member 154 and the central axis 15C of the sensor is changed to three patterns of 0°, 10°, and 20°. It shows the reception voltage of the reception signal output from the reception main unit 152B when the distance L1 is changed between ₃ mm and 10 mm.
In FIG. 6, signal A1 is a received signal when the normal to protective member 154 and sensor central axis 15C are parallel. A signal A2 is a signal received when the first angle θ between the normal to the protective member 154 and the sensor central axis 15C is 10°. A signal A3 is a signal received when the first angle θ between the normal to the protective member 154 and the sensor central axis 15C is 20°.
Considering the visibility of the signal A2, the display of the signal A3 when the distance L1 is changed from ₃ mm to 5 mm is omitted, but the same waveform is obtained after 5 mm.

When the normal line of the protective member 154 and the central axis _15C of the sensor are parallel, as indicated by the signal A1 in FIG. The value (received voltage) fluctuates greatly. That is, when the relationship between the distance L ₁ from the transmission surface 151C to the protective member 154 and the wavelength λ of the ultrasonic wave is L ₁ =m×λ/2 (where m is an integer), the ultrasonic wave due to multiple reflection components reinforce each other. Also, when the relationship between the distance L ₁ and the wavelength λ of the ultrasonic wave is L ₁ ={(2m+1)/4}×λ, the ultrasonic waves due to multiple reflection components weaken each other.
_In this way, when the variation in the voltage value of the received signal increases when the distance L1 is changed, it means that the multiple reflection component of the ultrasonic wave is being received by the receiving section 152 . In such a case, noise components due to multiple reflected ultrasonic waves are included in the received signal, and the detection accuracy decreases when detecting double feeding based on the received signal.

On the other hand, by setting the _first angle θ to 10° or more as in the signal A2 and the signal A3, the variation of the received signal when the distance L1 is changed becomes small. This means that the multiple reflection component of the ultrasonic waves received by the receiver 152 is reduced. That is, by increasing the first angle θ, noise due to multiple reflection components can be suppressed, and detection accuracy can be improved when double feeding is detected based on received signals.

FIG. 7 shows the transmission from the receiving unit 152 when the transmitting unit 151 is caused to output an ultrasonic wave when the protective member 154 is arranged perpendicular to the sensor central axis 15C and the paper P is not arranged in the conveying path 130. FIG. 4 is a diagram showing waveforms of received signals;
In FIG. 7, a signal D1 is a received signal based on an ultrasonic wave that is input to the receiving body 152B without being reflected by any member.
Signal D2 is received based on ultrasonic waves transmitted from transmitting section 151, which are reflected by protective member 154 on the transmitting section 151 side, reflected by transmitting section 151, and then input to main receiving section 152B. is a signal.
The signal D3 is based on the ultrasonic wave that is reflected by the receiving unit 152, re-reflected by the protective member 154 on the side of the receiving unit 152, and then input to the main receiving unit 152B among the ultrasonic waves transmitted from the transmitting unit 151. is the received signal.
The signal D4 is received based on the ultrasonic waves that are reflected by the receiving section 152, reflected by the protective member 154 on the side of the transmitting section 151, and then input to the receiving main body section 152B among the ultrasonic waves transmitted from the transmitting section 151. is a signal.
A signal D5 is a received signal based on the ultrasonic wave that is reflected by the receiving unit 152, re-reflected by the transmitting unit 151, and then input to the main receiving unit 152B among the ultrasonic waves transmitted from the transmitting unit 151.

FIG. 8 shows two examples of changes in the signal D2 in FIG. 7 when the first angle θ between the normal to the protective member 154 and the sensor central axis 15C is changed, with L ₁ =10 mm and 30 mm. It is a diagram indicated by . As shown in FIG. 8, when the first angle θ between the normal to the protective member 154 and the sensor central axis 15C is increased, the voltage value of the received signal is decreased.

In order to suppress deterioration in detection accuracy of double feeding due to received signals based on multiple reflection, the voltage value of the received signal should be at least half the value of the received voltage when the first angle θ is 0°. , the inclination angle of the protective member 154 is preferably set.
In this case, as shown in FIG. 8, by setting the first angle θ to 5° or more, the voltage value of the received signal is less than half the value of the received signal when θ= ₀ ° regardless of the distance L1. , and it is possible to suppress multiple reflections between the protective member 154 and the transmission body 151B.
This relationship also holds in the receiver 152 . Therefore, by setting the first angle θ to 5° or more in the receiving section 152 as well, it is possible to suppress multiple reflection between the protective member 154 and the receiving body section 152B.

It is more preferable to set the first angle θ to 10° or more in each of the transmitting section 151 and the receiving section 152, taking into account the constructive and destructive effects of the ultrasonic waves due to the multiple reflection components described above.
FIG. 9 is a diagram showing the positional relationship between the protection member 154 and the receiver body 152B.
Let L2 be the distance between the protective member 154 and the receiving surface 152C _on the sensor central axis 15C. When an ultrasonic wave that is input to the receiving main body portion 152B along the sensor central axis 15C is reflected by the receiving surface 152C and re-reflected by the protective member 154 on the side of the receiving portion 152, the re-reflected ultrasonic wave is In the same plane as the receiving surface 152C, the input is made at a position separated from the sensor center axis 15C by a distance Ld=L ₂ ·tan (2θ).

As shown in FIG. 9, when the width of the receiving surface 152C in the plane including the sensor central axis 15C is W _A , it is preferable to provide the receiving body portion 152B satisfying W _A /2<Ld. That is, the width W _A of the receiving surface 152C preferably satisfies W _A <2L ₂ ·tan(2θ). As a result, it is possible to further suppress the inconvenience of receiving the ultrasonic waves re-reflected by the protective member 154 by the receiving body 152B.
More preferably, the width W _A of the receiving surface 152C satisfies W _A <Ld. That is, it is more preferable that the width W _A of the receiving surface 152C satisfies W _A <L ₂ ·tan(2θ). In this case, regardless of the position at which the ultrasonic waves are input to the receiving surface 152C, it is possible to prevent the ultrasonic waves reflected by the receiving surface 152C from being re-reflected by the protective member 154 and entering the receiving surface 152C again.
This relationship is also established in the transmission main unit 151B. Therefore, when the width of the transmission surface 151C is W _B , it is preferable to provide the transmission main body 151B satisfying W _B <2L ₁ ·tan(2θ), more preferably W _B <L ₁ ·tan( 2θ) is preferably satisfied.

Further, when an ultrasonic wave is transmitted from the transmission body portion 151B, in addition to the direction from the transmission surface 151C to the reception portion 152, the sensor also moves toward the transmission base portion 151A from the transmission side fixed surface 151B1 opposite to the transmission surface 151C. Ultrasonic waves are transmitted along the central axis 15C.
Here, when the normal to the base end surface 151A1 of the transmission base portion 151A coincides with the sensor center axis 15C, multiple reflections of ultrasonic waves occur between the base end surface 151A1 and the transmission body portion 151B. . Therefore, the multiple-reflected ultrasonic waves are superimposed on the ultrasonic waves traveling from the transmitting surface 151C toward the receiving unit 152, and the sound pressure of the transmitted ultrasonic waves fluctuates. .

On the other hand, in the present embodiment, as shown in FIG. 3, the proximal side end surface 151A1 of the transmission base portion 151A is inclined with respect to the distal side end surface 151A2. That is, the normal to the base end surface 151A1 is inclined with respect to the sensor central axis 15C.
As a result, the ultrasonic waves transmitted along the sensor central axis 15C from the transmitting main body 151B toward the transmitting base 151A are reflected by the base end surface 151A1 in a direction different from the sensor central axis 15C. multiple reflection is suppressed.

Here, when the voltage of the received signal is measured when the angle of the normal line of the base end face 151A1 with respect to the sensor central axis 15C is changed, measurement results substantially similar to those in FIG. 8 are obtained. That is, when the angle of the normal to the base end face 151A1 with respect to the sensor center axis 15C is within the range of ±5°, the received signal becomes large due to the multiple reflection component, and the double feeding detection accuracy becomes unstable.
On the other hand, by setting the angle of the normal to the base end face 151A1 with respect to the sensor central axis 15C to 5° or more, the influence of multiple reflection is suppressed, and by setting the angle to 10° or more, the influence of multiple reflection is reduced. It becomes possible to suppress more effectively.

[Circuit Configuration of Ultrasonic Sensor 15]
FIG. 10 is a block diagram showing the control configuration of the image scanner 10. As shown in FIG.
In this embodiment, as the circuit configuration of the ultrasonic sensor 15, the transmission circuit board 31 is provided with a transmission control circuit for controlling the driving of the transmission section 151, and the reception circuit board 32 is provided with a reception processing circuit for controlling the driving of the reception section 152. A circuit is provided. The circuit configuration of the ultrasonic sensor 15 is not limited to this. A circuit configuration for controlling the transmitter 151 may be provided integrally with the receiver circuit board 32 . In addition, these circuit configurations may be configured by a plurality of circuit boards.

In this embodiment, as shown in FIG. 10, a transmission circuit 311 is provided on the transmission circuit board 31 .
The transmission circuit 311 is electrically connected to each ultrasonic transducer Tr of the transmission body 151B, and generates a drive signal for driving each ultrasonic transducer Tr.

Further, the receiving circuit board 32 is provided with a receiving circuit and the like for processing the received signal and outputting it to the control section 16 . As the receiving circuit, a general circuit that processes a received signal input by receiving ultrasonic waves can be used. As shown in FIG. 10, the receiving circuit can be composed of a bandpass filter 321, an amplifier 322, a sample-and-hold circuit 323, a comparator 324, and the like. A received signal output from the main receiving unit 152B is input to the bandpass filter 321 . This received signal has noise components and the like removed by the bandpass filter 321 , is amplified by the amplifier 322 so as to have a predetermined signal strength or more, and is input to the sample-and-hold circuit 323 . The sample-and-hold circuit 323 samples the received signal at a predetermined frequency, and the sampled received signal is input to the comparator 324 . The comparator 324 detects a received signal whose signal strength exceeds a predetermined threshold among the sampled received signals and inputs it to the control unit 16 .

[Configuration of control unit 16]
As shown in FIG. 10, the control unit 16 includes a calculation unit 161 configured by a CPU (Central Processing Unit) or the like, and a storage unit 162 configured by a recording circuit such as a memory.
The control unit 16 is connected to the transport motor 135 , the scanning unit 14 and the ultrasonic sensor 15 of the transport unit 13 and controls driving of these transport motor 135 , the scanning unit 14 and the ultrasonic sensor 15 . The control unit 16 is connected to the interface unit 17 and receives various data and signals input from an external device 51 such as a personal computer, and outputs read data read by the image scanner 10 to the external device 51 . or

Various data and various programs for controlling the image scanner 10 are recorded in the storage unit 162 .
By reading and executing various programs stored in the storage unit 162, the calculation unit 161 functions as a conveyance control unit 161A, a reading control unit 161B, a multi-feed determination unit 161C, and the like, as shown in FIG.

The transport control unit 161A controls the transport motor 135 of the transport unit 13 to rotate the plurality of roller pairs 131 to 134, thereby feeding the paper P set on the paper support 12 into the apparatus main body 11 one by one. send. Further, the transport control unit 161A transports the fed paper P along the transport path 130. FIG.
The reading control unit 161B controls the scanning unit 14 to read the image of the paper P while the paper P is being conveyed.

The multi-feed determination unit 161C is a state detection unit that detects the state of the paper P. In this embodiment, the ultrasonic sensor 15 is controlled to detect the state of the paper P based on the received signal input from the reception unit 152. Judge double feeding.
Specifically, when the voltage value of the received signal is smaller than a predetermined threshold value, it is determined that the sheets P are multi-fed. It should be noted that the transport control unit 161A stops the transport of the paper P when the multi-feeding determination unit 161C determines that the paper P is multi-feeding.

[Action and effect of the present embodiment]
The ultrasonic sensor 15 of this embodiment includes a transmission unit 151 that performs transmission processing for transmitting ultrasonic waves to the paper P along the sensor central axis 15C, and an ultrasonic wave that is input from the paper P along the sensor central axis 15C. and a receiving unit 152 that performs a receiving process for receiving. In this embodiment, a mesh-shaped protective member 154 is provided between the transmitting section 151 and the paper P and between the receiving section 152 and the paper P. As shown in FIG.
In such a configuration, the protective member 154 can prevent foreign substances such as paper dust from entering, and can prevent the foreign substances from adhering or accumulating on the transmitting surface 151C or the receiving surface 152C. Therefore, it is possible to suppress a decrease in the ultrasonic wave transmission/reception sensitivity of the ultrasonic sensor 15 .
Further, in the image scanner 10, since ultrasonic wave transmission/reception processing can be performed by the ultrasonic wave sensor 15 with high transmission/reception sensitivity, multi-feeding of the paper P can be accurately performed based on the reception signal output from the reception main unit 152B. Detection can be performed.

The ultrasonic sensor 15 of the present embodiment includes a shield portion 153 having a substantially tubular shield wall 153A with the sensor central axis 15C as the central axis. The transmitting section 151 and the receiving section 152 are arranged so as to be surrounded by a shield wall 153A of the shield section 153. The shield section 153 extends from the position surrounding the transmitting section 151 and the receiving section 152 to the transport path 130 along which the sheet P is transported. It extends to the side. A passage hole 153C through which ultrasonic waves pass is provided at the extension tip portion of the shield portion 153 on the conveying path 130 side, and a protection member 154 is provided to cover the passage hole 153C.
Therefore, the transmitting section 151 and the receiving section 152 are surrounded by the protective member 154 and the shield section 153 . That is, the protection member 154 can prevent foreign matter from entering from directions along the sensor central axis 15C, and the shield portion 153 can prevent foreign matter from entering from directions other than the sensor central axis 15C.
In addition, since the shield part 153 is made of a conductive material, it is possible to suppress the effects of static electricity and electromagnetic waves on the transmission main body part 151B and the reception main body part 152B.

In the ultrasonic sensor 15 of this embodiment, the normal line of the protection member 154 is inclined with respect to the sensor central axis 15C.
Therefore, in the ultrasonic sensor 15 of the present embodiment, multiple reflection of ultrasonic waves between the transmitter 151 and the protective member 154 and multiple reflection of ultrasonic waves between the receiver 152 and the protective member 154 are suppressed. can do.
In particular, when the ultrasonic sensor 15 is used as a multi-feed sensor as in the present embodiment, the reception signal increases when the receiving section 152 receives multiple reflection components of ultrasonic waves. In this case, even when a plurality of sheets P are conveyed to the conveying path 130, a reception signal having a predetermined voltage value or more may be output, and there is a possibility that double feeding of the sheets cannot be properly determined. On the other hand, in the present embodiment, the inconvenience of inputting the multiple reflection component of the ultrasonic wave to the receiving unit 152 is suppressed, and double feeding can be detected with high detection accuracy.

In this embodiment, the normal to the protective member 154 is inclined at a first angle θ of 5° or more with respect to the sensor central axis 15C.
In this case, the voltage value of the received signal caused by the ultrasonic waves multiple-reflected between the main receiving unit 152B and the protective member 154 on the receiving unit 152 side is the received signal when the first angle θ = 0°. can be less than half the voltage value of Also, the distance between the protection member 154 on the transmission section 151 side and the reception body section 152B is greater than the distance between the protection member 154 on the reception section 152 side and the reception body section 152B. Therefore, even when the ultrasonic waves that are multiple-reflected between the main receiving section 152B and the protective member 154 on the transmitting section 151 side are input to the main receiving section 152B, the received voltage is the first angle θ=0° is less than half the voltage value of the received signal.
That is, by setting the first angle θ to 5° or more as described above, it is possible to reduce the voltage value of the received signal when the multiple reflection component of the ultrasonic wave is received by the receiving main unit 152B, thereby suppressing variations in the received signal. can do. As a result, stable multi-feeding detection processing can be performed.

In this embodiment, the protection member 154 is configured in a mesh shape by arranging _a plurality of wires 154A along the Xm direction and the Ym direction. smaller than the wavelength of the transmitted ultrasound. Therefore, it is possible to prevent the ultrasonic waves transmitted by the transmission unit 151 from being irregularly reflected by the protective member 154 .

The image scanner 10 of the present embodiment has a multi-feed determination unit 161C that detects multi-feed of the paper P based on the reception signal output from the reception unit 152 of the ultrasonic sensor 15 as described above. there is As described above, in the present embodiment, adhesion and deposition of foreign matter on the transmitter 151 and the receiver 152 of the ultrasonic sensor 15 are suppressed, so the transmission sensitivity of the transmitter 151 and the reception sensitivity of the receiver 152 are increased. can be maintained. Therefore, the multi-feed determination unit 161C can accurately determine the multi-feed of the sheets P based on the received signal output from the ultrasonic sensor 15 as described above.

[Second embodiment]
Next, a second embodiment will be described.
The second embodiment differs from the first embodiment in that a sound absorbing portion is further provided in the shield portion 153 shown in the first embodiment.
In the following description, items that have already been described are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

FIG. 11 is a cross-sectional view showing a schematic configuration of an ultrasonic sensor 15A according to the second embodiment.
In this embodiment, the ultrasonic sensor 15A includes a transmitter 151, a receiver 152, a shield 153, and a protective member 154, as in the first embodiment.
In this embodiment, the sound absorbing portion 155 is provided on the surface of the shield portion 153 facing the transport path 130, that is, the surface of the protruding portion 153B facing the transport path 130. As shown in FIG.
The sound absorbing portion 155 is configured by providing a porous member such as urethane. In this embodiment, as shown in FIG. 11, an example in which a sound absorbing portion 155, which is a porous member having a sound absorbing characteristic, is provided on the protruding portion 153B is shown, but the present invention is not limited to this. As the sound absorbing portion 155, the surface of the protruding portion 153B facing the conveying path 130 may be subjected to surface roughening or the like to scatter ultrasonic waves.

12 and 13 are diagrams showing changes in the received signal by the sound absorbing portion 155. FIG. FIG. 12 shows the case where the distance LP from the surface of the protective member 154 facing the paper _P to the paper P on the transmission unit 151 side is changed when the shield 153 is not provided with the sound absorbing portion 155 and the protective member 154. is a diagram showing changes in the received signal of . FIG. 13 is a diagram showing changes in the received signal when the distance _LP is changed when the sound absorbing portion 155 is provided in the shield portion 153 without providing the protective member 154 .
When the sound absorbing portion 155 is not provided in the shield portion 153, as shown in FIG. 12, the variation in the voltage value of the received signal increases when the distance LP is changed, and the variation in the _voltage value is 5.9%. became. This indicates that the ultrasonic wave component multiple-reflected between the projecting portion 153B and the paper P is large.
On the other hand, as shown in FIG. 13, when the sound absorbing portion 155 was provided in the shield portion 153, the variation in the _voltage value of the received signal was 2.1% when the distance LP was varied. That is, by providing the sound absorbing portion 155, the ultrasonic waves multiple-reflected between the projecting portion 153B and the paper P are reduced.

[Action and effect of the present embodiment]
In this embodiment, the following effects can be obtained in addition to the effects described in the first embodiment.
The ultrasonic sensor 15A of the present embodiment is provided with a sound absorbing portion 155 surrounding the passage hole 153C on the surface of the projecting portion 153B of the shield portion 153 facing the paper P. As shown in FIG.
With such a configuration, multiple reflection of ultrasonic waves between the shield part 153 and the paper P can be suppressed. As described above, when the multiple reflection component is received by the receiving unit 152, the received signal becomes large, so there is a possibility that the multi-feeding of the sheets P cannot be properly determined. In the present embodiment, such multiple reflection components can be suppressed, and multi-feeding of sheets P can be properly determined.

[Third embodiment]
Next, a third embodiment will be described.
In the first embodiment and the second embodiment, the normal line of the protective member 154 is inclined at the first angle θ with respect to the sensor center axis 15C, and matches the normal line of the target paper P. . In contrast, the third embodiment differs from the first and second embodiments in that the normal line of the protective member 154 is inclined with respect to the normal line of the paper P. FIG.

FIG. 14 is a cross-sectional view showing a schematic configuration of an ultrasonic sensor 15B according to the third embodiment.
In FIG. 14, the sound absorbing portion 155 is provided on the projecting portion 153B as in the second embodiment.
In this embodiment, the sensor center axis 15C is inclined at the first angle θ with respect to the normal line of the paper P, as shown in FIG. Also, the normal to the protruding portion 153B, that is, the normal to the XmYm plane of the protective member 154 is inclined with respect to the normal to the paper P at a second angle φ different from the first angle θ.
That is, the normal line of the protective member 154 is inclined at an angle θ−φ with respect to the sensor central axis 15C, and the XmYm plane of the protective member 154 is inclined at an angle θ+φ and is slanted.

FIG. 15 is a diagram showing received signals when the distance LP from the surface of the protective member 154 on the transmission unit 151 side facing the paper P to the paper _P is varied in the second embodiment. FIG. 16 is a diagram showing received signals when the distance _LP is varied in the third embodiment.
In the first embodiment and the second embodiment, multiple reflection between the receiving surface 152C and the protective member 154 and between the transmitting surface 151C and the protective member 154 can be suppressed. Further, in the second embodiment, multiple reflection between the protruding portion 153B and the paper P can be suppressed by providing the sound absorbing portion 155 . However, as shown in FIG. 15, when the distance LP was changed, the voltage value of the received signal varied slightly, and the _voltage value variation was 6.1%. This indicates that multiple reflection occurs between the protective member 154 and the paper P transported on the transport path 130 because the protective member 154 and the paper P transported to the transport path 130 are parallel or substantially parallel.

On the other hand, as shown in FIG. 16, in the third embodiment, the degree of variation in the _voltage value of the received signal was 0.8% when the distance LP was varied. This means that multiple reflection between the protective member 154 and the paper P is suppressed.
That is, in this embodiment, between the receiving surface 152C and the protective member 154, between the transmitting surface 151C and the protective member 154, between the projecting portion 153B and the paper P, and between the protective member 154 and the paper P In each of the above, multiple reflection of ultrasonic waves is suppressed, and it is possible to effectively suppress the inconvenience of noise components caused by multiple reflection being superimposed on the received signal.

[Action and effect of the present embodiment]
In this embodiment, the following effects can be obtained in addition to the effects of the first embodiment and the second embodiment described above.
That is, in this embodiment, the sensor center axis 15C is inclined at the first angle θ with respect to the normal line of the transport path 130 along which the paper P is transported, as in the first embodiment. Also, the normal to the XmYm plane of the protective member 154 is inclined at a second angle φ different from the first angle θ with respect to the normal to the transport path 130 .
In this case, multiple reflection of ultrasonic waves between the protective member 154 and the paper P can be suppressed in addition to between the transmitting section 151 and the protective member 154 and between the receiving section 152 and the protective member 154 . Further, as in the second embodiment, multiple reflection of ultrasonic waves between the projecting portion 153B and the paper P can be suppressed by providing the sound absorbing portion 155 surrounding the passage hole 153C.
For this reason, in the present embodiment, it is possible to further suppress the inconvenience of receiving the multiple-reflected ultrasonic waves by the receiving unit 152, and it is possible to appropriately determine whether the sheets P are multi-fed.

[Modification]
In addition, the present invention is not limited to the above-described embodiments, and includes modifications, improvements, and configurations obtained by appropriately combining each embodiment within the scope of achieving the object of the present invention. It is.

[Modification 1]
In the above-described first to third embodiments, the example in which the sensor center axis 15C is inclined with respect to the normal line of the paper P is shown, but the present invention is not limited to this. FIG. 17 is a diagram showing the configuration of an ultrasonic sensor 15D according to Modification 1. As shown in FIG.
As shown in FIG. 17, the transmitter 151 may be arranged such that the sensor central axis 15C is parallel or substantially parallel to the normal line of the paper P. As shown in FIG. In this case, the normal line of the protective member 154 is configured to be inclined to the sensor central axis 15C.
In such a configuration, multiple reflection between the transmitting section 151 and the protective member 154 and between the receiving section 152 and the protective member 154 is suppressed. Also, multiple reflections between the protective member 154 and the paper P are suppressed. In addition, the space for arranging the ultrasonic sensor 15D can be made smaller than when the sensor central axis 15C is inclined. In addition, since the space for arranging the ultrasonic sensor 15D can be reduced, the size of the electronic device such as the image scanner 10 can be reduced.

[Modification 2]
FIG. 18 is a cross-sectional view showing the configuration of an ultrasonic sensor 15E according to Modification 2. As shown in FIG.
In the third embodiment, the configuration in which the normal to the sensor central axis 15C and the protective member 154 is inclined with respect to the normal to the paper P has been described. Here, in the third embodiment, the transmission surface 151C and the protection member 154 on the side of the transmission unit 151 are inclined in the same direction with respect to the normal line of the paper P, that is, in FIG. Indicated.
On the other hand, the sensor central axis 15C may be inclined in a different direction with respect to the normal line of the paper P, as shown in FIG. As shown in FIG. 18, the transmitting surface 151C and the receiving surface 152C may be arranged so that the right shoulder is upward, and the protective member 154 is arranged so that the right shoulder is downward.

[Modification 3]
19 and 20 are diagrams showing configurations of ultrasonic sensors 15F and 15G according to Modification 3. FIG.
In each of the above-described embodiments, the protective member 154 has a planar shape by arranging a plurality of wires 154A on the XmYm plane. On the other hand, as in an ultrasonic sensor 15F shown in FIG. 19, the protection member 154 may be bent to have two inclined surfaces. Also, as in an ultrasonic sensor 15G shown in FIG. 20, the protection member 154 may have a curved surface. In either case, multiple reflection between the protective member 154 and the ultrasonic element and multiple reflection between the protective member 154 and the paper P can be suppressed.

19 and 20 are examples in which the sensor center axis 15C is inclined with respect to the normal line of the paper P, but as shown in FIG. In this case, similarly, the protection member 154 may be bent to have two inclined surfaces, or may have a curved surface.

[Modification 4]
In each of the above-described embodiments, the protection member 154 has an example in which a plurality of wires 154A are arranged along the Xm direction and the Ym direction to form a mesh, but the protection member 154 is not limited to this.
21 to 25 are plan views showing schematic configurations of protective members according to modifications.
For example, as shown in FIG. 21, the protection member 154C may be configured by arranging a plurality of wires 154C1 in parallel. The plurality of wires 154C1 may be parallel to the Xm direction, may be parallel to the Ym direction, or may be parallel to directions inclined in the Xm direction and the Ym direction. In this case, the gap 154C2 between the adjacent wires 154C1 corresponds to a hole through which ultrasonic waves pass along the central axis of the sensor.

Further, as shown in FIG. 22, the protective member 154D may be configured by a flat plate, for example, and provided with a plurality of through holes 154D1 penetrating the flat plate in the plate thickness direction.
In the example shown in FIG. 22, the through-hole 154D1 has a configuration in which a plurality of square-shaped through-holes 154D1 are provided along the Xm direction and the Ym direction, but the shape of the through-hole 154D1 is not limited to this. For example, as shown in a protective member 154E shown in FIG. 23, a slit-shaped through hole 154E1 extending in one direction may be provided.
Furthermore, a configuration in which a plurality of through-holes having different shapes are provided in the flat plate-shaped protection member may be employed.
For example, in the protection member 154F shown in FIG. 24, the through holes 154F1 are arranged along a plurality of concentric circles centered on the central point of the protection member 154F, each having a different arc length.
Further, as shown in a protective member 154G shown in FIG. 25, a configuration may be adopted in which a plurality of through holes 154G1 having different shapes and sizes are arranged.
These through holes 154D1, 154E1, 154F1, and 154G1 correspond to holes through which ultrasonic waves pass along the central axis of the sensor.

Furthermore, the gaps 154B and 154C2 in the above embodiment and FIG. 21, and the through holes 154D1, 154E1, 154F1 and 154G1 shown in FIGS. A hole extending along 15C, but not limited to this.
For example, the protective member may be composed of a porous member. Examples of the porous member include a nonwoven fabric and a foam material having an open cell structure. In such a protective member, the interstices of the non-woven fabric and the open-cell structure of the foam material serve as holes that allow communication from the transmitting section 151 side surface of the protective member to the receiving section 152 side surface, and the sensor center axis 15C. to pass ultrasonic waves along.
In addition, any shape may be employed as long as it has a plurality of holes that allow communication from one surface of the protective member to the other surface and allows ultrasonic waves to pass through the holes along the central axis of the sensor.

[Modification 5]
In the first embodiment, the transmitting section 151 and the receiving section 152 constituting the ultrasonic sensor 15 each have a shield section 153 having a substantially cylindrical shield wall 153A, and one end of the shield section 153 is connected to the transmission circuit board. 31 or the receiving circuit board 32. FIG. In addition, the shield part 153 has a substantially tubular shield wall 153A, and is configured such that the transmission base part 151A and the transmission main body part 151B or the reception base part 152A and the reception main body part 152B are provided inside the tube.
On the other hand, the configuration of the shield portion is not limited to the above embodiment, and may be configured as shown in FIG. 26, for example.
FIG. 26 is a schematic cross-sectional view of a transmitter 151D according to Modification 5. As shown in FIG. Although the transmission section 151D will be described here, the reception section can have the same configuration.
In FIG. 26, the direction parallel to the sensor center axis 15C is the Zh direction, the direction orthogonal to the Zh direction is the Xh direction, and the Zh direction and the direction orthogonal to the Xh direction are the Yh direction, and ultrasonic waves are transmitted in the +Zh direction. will be described below. FIG. 26 is a cross-sectional view of the transmission section 151D taken along a plane parallel to the XhZh plane including the Xh direction and the Zh direction.
As shown in FIG. 26, the transmission unit 151D includes a transmission base portion 151E to which the transmission main body portion 151B is joined, a first shield portion 153D1 and a second shield portion 153D2 that are arranged to sandwich the transmission base portion 151E, have
The first shield part 153D1 and the second shield part 153D2 are tubular members having a central axis parallel to the sensor central axis 15C, and the shape of the inner peripheral surface of the cylinder when viewed along the Zh direction is oriented in the Xh direction. It has a rectangular shape with two parallel sides and two sides parallel to the Yh direction.

FIG. 27 is a perspective view of the transmission base portion 151E. FIG. 28 is a plan view of the transmission base portion 151E viewed from the +Zh side.
The transmission pedestal portion 151E is a block-shaped member that is rectangular in plan view when viewed from the sensor central axis 15C. and a side edge 151G.
A joint surface 151F1 (third surface) orthogonal to the sensor center axis 15C is provided at the tip end 151F. A transmission-side fixed surface 151B1 (second surface) opposite to the transmission surface 151C (first surface) of the transmission body 151B is bonded to the joint surface 151F1.
In addition, a plurality of stepped portions 151F2 for positioning the transmission body portion 151B are provided at the tip end portion 151F. For example, in the example shown in FIG. 28, the stepped portions 151F2 are provided on the ±Yh side and the -Xh side of the joint surface 151F1, respectively, and position the transmitter body portion 151B.

The proximal end portion 151G has an inclined end surface 151G1 (fourth surface), a connection surface 151G2, and a substrate joint portion 151G3.
The inclined end surface 151G1 is a surface whose normal is inclined with respect to the sensor central axis 15C, and is provided at a position overlapping the transmitting surface 151C of the main transmitting body 151B in a plan view along the sensor central axis 15C. . In this example, the inclined end surface 151G1 is inclined toward the -Zh side toward the +Xh side, but the inclination direction of the inclined end surface 151G1 is not limited to this. It may be tilted or may be tilted in another direction.
The connection surface 151G2 is a surface continuous from the inclined end surface 151G1 on the +Xh side of the inclined end surface 151G1. A wiring hole 151H penetrating from the connection surface 151G2 to the joint surface 151F1 is provided in the transmission base portion 151E, and the wiring or FPC connecting the transmission main body portion 151B and the transmission circuit board 31A is inserted through the wiring hole 151H. be done.

A pair of substrate joint portions 151G3 are provided at both ends in the Yh direction of the inclined end surface 151G1 so as to sandwich the inclined end surface 151G1. The substrate joint portion 151G3 is a protruding portion that protrudes toward the −Zh side from the inclined end surface 151G1, and the substrate joint surface 151G4 that contacts the transmission circuit board 31A and the end portion of the transmission circuit board 31A are positioned on the projecting tip side. A holding portion 151G5 is provided. Specifically, the substrate joint surface 151G4 is a plane that is inclined with respect to the sensor central axis 15C, and is a plane that is substantially parallel to the extending direction of the wiring cable 31A2 connected to the transmission circuit board 31A via the connector 31A1. be. Further, the substrate holding portion 151G5 is configured by a surface rising in a direction intersecting the substrate bonding surface 151G4.
By fixing the transmission circuit board 31A to the board joint surface 151G4, the ultrasonic waves transmitted from the transmission side fixing surface 151B1 of the transmission main body 151B to the transmission base portion 151E side are directed along the sensor central axis 15C to the inclined end surface 151G1. and reaches the transmission circuit board 31A, it is reflected in a direction inclined with respect to the sensor center axis 15C by the transmission circuit board 31A. Therefore, it is possible to suppress multiple reflection due to the ultrasonic waves being reflected from the transmission circuit board 31A toward the sensor central axis 15C.

As shown in FIG. 28, the transmission base portion 151E has a shape in which a distal end portion 151F and a proximal end portion 151G overlap when viewed from above in the Zh direction. That is, the dimension along the Yh direction of the front end portion 151F and the dimension from the +Yh side end surface of the +Yh side substrate bonding portion 151G3 to the -Yh side end surface of the -Yh side substrate bonding portion 151G3 are the same dimension. It substantially matches the Yh-direction dimension of the cylinder inner peripheral surface of the first shield portion 153D1 and the second shield portion 153D2.
In addition, the dimension along the Xh direction of the tip end portion 151F and the dimension from the -Xh side edge of the inclined end surface 151G1 to the +Xh side edge of the connection surface 151G2 are the same dimension, and the first shield portion 153D1 and the second shield part 153D2.
Then, on the peripheral surface of the transmission pedestal portion 151E, an exposed portion 151J1 that protrudes to the ±Yh side from the region where the distal end portion 151F and the proximal end portion 151G overlap when viewed in the Zh direction, A flange portion 151J2 projecting to the ±Xh side is provided.

When viewed in the Zh direction, the exposed portion 151J1 has a dimension substantially the same as the thickness of the first shield portion 153D1 and the second shield portion 153D2 from the area where the distal end portion 151F and the proximal end portion 151G overlap. It protrudes in the Yh direction. The exposed portion 151J1 has an exposed surface 151J3 parallel to the XhZh plane. The exposed surface 151J3 can position the transmitter 151D by coming into contact with a fixed portion in the electronic device to which the transmitter 151D is fixed.
When viewed in the Zh direction, the flange portion 151J2 has a dimension substantially equal to the thickness of the first shield portion 153D1 and the second shield portion 153D2 from the region where the distal end portion 151F and the proximal end portion 151G overlap. It protrudes in the Xh direction.

The first shield portion 153D1 is provided on the +Zh side of the transmission base portion 151E, and the -Zh side end contacts the exposed portion 151J1 and the +Zh side end surface of the collar portion 151J2. As a result, a +Zh side portion of the transmission base portion 151E including the tip end portion 151F to which the transmission main body portion 151B is fixed is arranged on the inner circumference of the cylinder of the first shield portion 153D1.
A first passage hole 153C1 is provided along the sensor central axis 15C on the −Zh side of the first shield portion 153D1, and a transmission surface 151C of the transmission body portion 151B is arranged facing the first passage hole 153C1. be.

A second passage hole 153C2 communicating with the first passage hole 153C1 is provided at the +Zh side open end of the first shield portion 153D1. The second passage hole 153C2 is a hole portion having a first inclined central axis 15C1 inclined with respect to the sensor central axis 15C, and a hole cross section perpendicular to the first inclined central axis 15C1 is the sensor center of the first passage hole 153C1. It is larger than the hole cross-section perpendicular to the axis 15C. Between the first through hole 153C1 and the second through hole 153C2, a step surface 153C3 is provided that connects the edge of the first through hole 153C1 to the edge of the second through hole 153C2. The stepped surface 153C3 is a plane perpendicular to the first inclined center axis 15C1, and the protective member 154 is arranged on the stepped surface 153C3. Thereby, the normal line of the protection member 154 is inclined with respect to the sensor central axis 15C.
A cap 153E having a third passage hole 153E1, which is a through hole along the sensor center axis 15C, is fitted to the +Zh side end surface of the first shield portion 153D1. The cap 153E holds the protective member 154 by sandwiching the protective member 154 with the step surface 153C3.

The second shield portion 153D2 is provided on the −Zh side of the transmission base portion 151E, and the +Zh side end contacts the −Zh side end faces of the exposed portion 151J1 and the collar portion 151J2. As a result, a part of the transmission base portion 151E on the -Zh side including the proximal end portion 151G is arranged on the cylinder inner peripheral side of the second shield portion 153D2.
The second shield part 153D2 includes a tubular first tubular part 153D3 having a central axis that is the sensor central axis 15C, and a tubular second tubular part 153D3 that is centered around a second inclined central axis 15C2 that is inclined with respect to the sensor central axis 15C. and a cylindrical portion 153D4.
A transmission base portion 151E and a transmission circuit board 31A fixed to the transmission base portion 151E are arranged on the cylinder inner peripheral side of the first cylinder portion 153D3.
A wiring cable 31A2 connected to the transmission circuit board 31A is disposed on the second tubular portion 153D4, and the wiring cable 31A2 is pulled out from an open end of the second tubular portion 153D4 on the side opposite to the first tubular portion 153D3.

The transmission base portion 151A shown in the first embodiment has a configuration in which the proximal end surface 151A1 is fixed to the transmission circuit board 31, but the inclined end surface 151G1 of the transmission base portion 151E according to the fifth modification has Other members such as the transmission circuit board 31A are not joined. Therefore, the shape of the inclined end face 151G1 is not limited to the planar shape shown in FIGS. 27 and 28. FIG.
For example, as shown in FIGS. 29 and 30, the inclined end face 151G1 of the transmission base portion 151E may be bent.
As shown in FIG. 29, the inclined end surface 151G1 includes a first inclined surface 151G6 that inclines toward the +Zh side from the end on the -Xh side toward the +Xh side, and a first inclined surface 151G6 that inclines toward the +Xh side from the end on the +Xh side toward the -Xh side. and a second inclined surface 151G7 inclined to the +Zh side.
Further, as shown in FIG. 30, the inclined end surface 151G1 includes a third inclined surface 151G8 inclined toward the -Zh side from the -Xh side end toward the +Xh side, and a third inclined surface 151G8 inclined toward the -Xh side from the +Xh side end toward the -Xh side. and a fourth inclined surface 151G9 inclined toward the -Zh side as it goes.
In addition, the inclined end surface 151G1 may be curved in a cylindrical shape, a spherical shape, or may be formed in a cone shape.

[Modification 6]
In the first embodiment, the image scanner 10 was exemplified as an example of the electronic device, but the electronic device is not limited to this. In a printing apparatus (printer) provided with a print head for printing an image on the printing paper conveyed on the conveying path 130, the above-described ultrasonic sensor 15, 15A, 15B, 15D, 15E, 15F and 15G may be applied.

In such a printing apparatus, the ultrasonic sensors 15, 15A, 15B, 15D, 15E, 15F, and 15G may be used when determining the type of printing paper. That is, the printing apparatus stores table data that associates the signal strength of the signal received from the receiving unit 152 with the type of printing paper in the storage unit. A control unit (computer) provided in the printing apparatus functions as a state detection unit, refers to the table data, and determines the type of printing paper corresponding to the signal received from the reception unit 152 . In this case, the printing apparatus can form an optimum image on the printing paper according to the type of printing paper.
Further, the object is not limited to the paper P or the printed paper, and may be a film, a fabric, or the like, as described above.

Further, the ultrasonic sensors 15, 15A, 15B, 15D, 15E, 15F, and 15G as described above may be applied to a flow velocity detection device that detects the flow velocity of fluid flowing through a pipe or the like. In other words, when ultrasonic waves are transmitted to a fluid, which is an object, and ultrasonic waves passing through the fluid are received, the traveling direction of the ultrasonic waves changes according to the flow velocity of the fluid. At this time, the flow velocity of the fluid can be measured by detecting changes in the voltage value of the received signal. In such a flow velocity detection device, since the flow velocity of the fluid is measured from the voltage change of the received signal, it is necessary to accurately direct the sound axis of the ultrasonic waves transmitted from the transmitter to the receiver and set the reference position. There is By using the ultrasonic sensor as described above, the reference position can be accurately set, and the flow velocity detection accuracy of the flow velocity detection device can be improved.

Further, in the above-described embodiments, the ultrasonic sensors 15, 15A, 15B, 15D, 15E, 15F, and 15G including the transmitter 151 that transmits ultrasonic waves and the receiver 152 that receives ultrasonic waves are illustrated. On the other hand, the ultrasonic device may be configured with only a transmitting section that transmits ultrasonic waves, or may be configured with only a receiving section that receives ultrasonic waves.
For example, in ultrasonic devices such as data transmission devices that transmit data by ultrasonic waves, insect repellent devices and animal repellent devices that use ultrasonic waves to repel insects and animals, and tactile transmission devices that use ultrasonic waves for haptics, only the transmission part may be provided. Further, an ultrasonic device such as a data receiving device for receiving an ultrasonic signal transmitted from a data transmitting device using ultrasonic waves may be configured to include only a receiving section.
In an ultrasonic apparatus provided with only a transmitting section, transmission sensitivity is lowered when foreign matter adheres to the transmitting surface of the transmitting section. In addition, in an ultrasonic apparatus provided with only a receiving section, reception sensitivity is lowered when foreign matter adheres to the transmission surface of the receiving section. On the other hand, as described above, by providing a mesh-shaped protective member at a position a predetermined distance from the transmitting surface and the receiving surface, it is possible to suppress the intrusion of foreign matter, reduce the transmission sensitivity of the transmitting unit, and prevent the receiving unit from It is possible to suppress the decrease in the reception sensitivity of the
In addition, in an ultrasonic apparatus provided with only a transmission section, when multiple reflections of ultrasonic waves occur, residual vibration affects the accuracy of ultrasonic waves to be transmitted next. For example, in a data transmission device that transmits data using ultrasonic waves, residual signals may prevent the next transmission of data from being correctly transmitted. On the other hand, as in the above-described embodiment, if the protective member is configured to be inclined with respect to the normal line of the transmitting surface, multiple reflection can be effectively suppressed, so that the influence of residual signals can be suppressed.

Furthermore, although an example of an ultrasonic apparatus in which a transmitting unit and a receiving unit are separate units has been described, a configuration in which one transmitting/receiving unit that performs transmission/reception processing of ultrasonic waves is provided may be employed. In this case, the transmitting/receiving unit transmits ultrasonic waves to the object to be measured, and receives the reflected ultrasonic waves that have been reflected by the object to be measured and returned to the transmitting/receiving unit. In this case, it can be used as a distance measurement sensor that measures the distance from the ultrasonic sensor to the object to be measured based on the time from when the transmitter/receiver transmits the ultrasonic wave to when the transmitter/receiver receives the reflected ultrasonic wave. can be done.

In addition, the specific structure for carrying out the present invention may be configured by appropriately combining the above-described embodiments and modifications within the scope of achieving the object of the present invention, or may be appropriately changed to another structure. You may

DESCRIPTION OF SYMBOLS 10... Image scanner (electronic device), 15, 15A, 15B, 15D, 15E, 15F, 15G... Ultrasonic sensor, 16... Control part, 31... Transmission circuit board, 32... Receiving circuit board, 130... Conveyance path, 151 Transmitting portion 151A Transmitting base portion 151A1 Base end surface 151A2 Distal end surface 151B Transmitting body portion 151C Transmitting surface 152 Receiving portion 152A Receiving base portion 152A1 Base end End face 152A2 Tip side end face 152B Receiving body 152C Receiving surface 153 Shield part 153A Shield wall 153B Projection 153C Passing hole 154, 154C, 154D, 154E, 154F, 154G Protective member 154A, 154C1 Wire rod 154B, 154C2 Gap (rear part) 154D1, 154E1, 154F1, 154G1 Through hole 155 Sound absorbing part 161 Computing part 161C Multi-feed determining part.

Claims (8)

an ultrasonic element configured to at least one of transmit ultrasonic waves to an object along a first axis and receive ultrasonic waves input along the first axis;
a protective member provided on the first shaft and covering the ultrasonic element;
with
The protective member has a plurality of holes through which the ultrasonic waves traveling along the first axis pass, and a plurality of wire rods in a first direction intersecting the first axis, and the first axis and the arranged along a second direction intersecting the first direction,
the first axis is inclined at a first angle with respect to the normal of the object;
A normal line of a plane containing the first direction and the second direction is inclined at a second angle different from the first angle with respect to the normal line of the object.
An ultrasonic device characterized by: In the ultrasonic device according to claim 1,
A shield portion configured in a substantially cylindrical shape with the first axis as a central axis,
The ultrasonic element is arranged so as to be surrounded by the cylinder inner peripheral surface of the shield part,
The shield part extends along the first axis from a position surrounding the ultrasonic element, and has a passage hole for allowing the ultrasonic wave to pass through at the extending tip part,
The ultrasonic device, wherein the protection member is provided so as to cover the passage hole of the shield section. In the ultrasonic device according to claim 2,
The ultrasonic device according to claim 1, wherein a sound absorbing portion surrounding the passage hole is provided on a surface of the extending distal end portion of the shield portion opposite to the ultrasonic element. In the ultrasonic device according to claim 1 ,
The ultrasonic device, wherein a normal line of a plane including the first direction and the second direction is inclined at an angle of 5° or more with respect to the first axis. In the ultrasonic device according to any one of claims 1 to 4 ,
The ultrasonic element has a first surface on which the ultrasonic waves are transmitted or received and a second surface opposite to the first surface,
A pedestal for holding the ultrasonic element,
The pedestal includes a third surface orthogonal to the first axis, to which the second surface of the ultrasonic element is bonded, and a fourth surface provided on the opposite side of the third surface,
The ultrasonic device, wherein the normal to the fourth surface is inclined with respect to the first axis. In the ultrasonic device according to claim 5 ,
The ultrasonic device, wherein the normal to the fourth surface is inclined at an angle of 5° or more with respect to the first axis. In the ultrasonic device according to any one of claims 1 to 6 ,
A pair of the ultrasonic elements is provided, one of the pair of ultrasonic elements is a transmitting section that transmits the ultrasonic waves, and the other of the pair of ultrasonic elements is a receiving section that receives the ultrasonic waves. can be,
The ultrasonic device, wherein the transmitting section and the receiving section are provided at positions facing each other on the first axis. In the ultrasonic device according to any one of claims 1 to 7 ,
The ultrasonic element receives the ultrasonic wave from the object and outputs a received signal,
An ultrasound apparatus, comprising: a state detection unit that detects a state of the object based on the received signal.

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