Media transport device, image reading device

Abstract

To reduce the size of a device by devising the configuration and placement of conventional ultrasonic sensors.SOLUTION: An ultrasonic detection unit comprises a transmitter sensor chip, a receiver sensor chip, a transmitter board on which the transmitter sensor chip is mounted, and a receiver board on which the receiver sensor chip is mounted. The receiving board is provided with an amplifier that amplifies the received ultrasonic signal detected by the receiver sensor chip, and a shielding member that covers at least a portion of the amplifier. The height of the receiver sensor chip relative to the receiver board is lower than the height of the shielding member relative to the receiver board.SELECTED DRAWING: Figure 30

Description

[Technical Field]

[0001] The present invention relates to a medium transport device that transports a medium, and an image reading device that includes the medium transport device. [Background technology]

[0002] Conventionally, a technique for detecting double feeding of media using an ultrasonic sensor has been used, as shown in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-25242 Summary of the Invention [Problem to be solved by the invention]

[0004] The use of ultrasonic sensors tends to lead to an increase in the size of the device. In the prior art, there was room for improvement in terms of miniaturizing the device by devising the configuration and arrangement of the ultrasonic sensor. [Means for solving the problem]

[0005] In order to solve the above problem, the medium conveying device of the present invention is a medium conveying device comprising a first pair of rollers that conveys a medium in a conveying direction, a second pair of rollers arranged downstream of the first pair of rollers in the conveying direction, and an ultrasonic detection unit arranged between the first pair of rollers and the second pair of rollers in the conveying direction, wherein the ultrasonic detection unit comprises a transmitting sensor chip that emits ultrasonic waves along a first axis toward a first surface of the medium being conveyed, a receiving sensor chip that is arranged on the first axis at a position where the medium is sandwiched between the transmitting sensor chip and the receiving sensor chip and receives ultrasonic waves, a transmitting board on which the transmitting sensor chip is mounted, a receiving board on which the receiving sensor chip is mounted, a receiving board on which the receiving sensor chip is mounted, an amplifier that is mounted on the receiving board and amplifies the received signal of the ultrasonic waves received by the receiving sensor chip, and a shielding member that is mounted on the receiving board and covers at least a portion of the amplifier, wherein the height of the receiving sensor chip relative to the receiving board is lower than the height of the shielding member relative to the receiving board.

[0006] The image reading device of the present invention is characterized by including the medium transport device and a reading unit that is positioned downstream of the second roller pair in the transport direction and that reads an image on the medium. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a perspective view of the scanner as seen from the front. [Figure 2] A view of the scanner's document transport path from the width direction. [Figure 3] FIG. 2 is a block diagram showing a control system of the scanner. [Figure 4] FIG. 10 is a perspective view showing a state in which the second unit is opened relative to the first unit. [Figure 5] Floor plan of the first unit. [Figure 6] FIG. 2 is a perspective view showing a state in which a cover provided on the first unit is attached. [Figure 7]FIG. 2 is a perspective view of the first unit with a cover removed. [Figure 8] FIG. 3 is a perspective view of the first unit as seen from the rear side. [Figure 9] FIG. 10 is a perspective view showing a fixed state of the transmission board holder. [Figure 10] Floor plan of the second unit. [Figure 11] FIG. 10 is a perspective view showing a fixed state of the receiving board holder. [Figure 12] 3 is a perspective view showing the positional relationship between a first roller pair, a second roller pair, a third roller pair, and an ultrasonic detection unit. FIG. [Figure 13] FIG. [Figure 14] FIG. [Figure 15] FIG. [Figure 16] FIG. [Figure 17] FIG. [Figure 18] FIG. [Figure 19] FIG. [Figure 20] FIG. [Figure 21] FIG. 2 is a cross-sectional view showing the structure of a transmitting sensor chip. [Figure 22] FIG. 2 is a cross-sectional view showing the configuration of an ultrasonic detection unit. [Figure 23] FIG. 4 is a diagram showing the positional relationship between an ultrasonic detection unit and a first roller pair. [Figure 24] 10A and 10B are diagrams showing the positional relationship between the ultrasonic detection unit and the second roller pair or the third roller pair. [Figure 25] FIG. 4 is a diagram showing the configuration of a second roller pair. [Figure 26] FIG. 2 is a cross-sectional perspective view showing the structure of a first reading unit. [Figure 27] FIG. 4 is a diagram showing the positional relationship between the sensor substrate of the first reading unit, the transmitting sensor chip, and the transmitting substrate. [Figure 28] FIG. 10 is a diagram showing the positional relationship between the second reading unit, the receiving sensor chip, and the receiving board. [Figure 29] FIG. 10 is a diagram showing the areas occupied by the first roller pair, the second roller pair, the transport motor, the transmitting sensor chip, the transmitting board, the receiving sensor chip, and the receiving board. [Figure 30] FIG. [Figure 31] FIG. [Figure 32] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be briefly described below. a transmitting sensor chip that emits ultrasonic waves along a first axis toward a first surface of the medium being transported; a receiving sensor chip that receives ultrasonic waves and is positioned on the first axis so as to sandwich the medium between the transmitting sensor chip and the receiving sensor chip; a transmitting board on which the transmitting sensor chip is mounted, the transmitting board having a substrate surface on which the transmitting sensor chip is mounted; a receiving board on which the receiving sensor chip is mounted, the receiving board having a substrate surface on which the receiving sensor chip is mounted; an amplifier that is mounted on the receiving board and that amplifies the ultrasonic wave received by the receiving sensor chip; and a shielding member that is mounted on the receiving board and that covers at least a portion of the amplifier, wherein the height of the receiving sensor chip relative to the receiving board is lower than the height of the shielding member relative to the receiving board.

[0009] According to this aspect, the height of the receiving sensor chip relative to the receiving board is lower than the height of the shielding member relative to the receiving board, and therefore the dimensions of the device can be reduced in a configuration in which the receiving board is equipped with the ultrasonic receiving unit and the shielding member.

[0010] A second aspect is an aspect dependent on the first aspect, characterized in that the first axis is inclined with respect to the surface of the medium passing between the transmitting sensor chip and the receiving sensor chip, the thickness of the transmitting sensor chip is thinner than the thickness of the transmitting substrate, the thickness of the receiving sensor chip is thinner than the thickness of the receiving substrate, and at least a portion of the transmitting sensor chip and at least a portion of the receiving sensor chip are within the range of the second roller pair in a direction normal to the surface of the medium at the nip position of the second roller pair.

[0011] According to this aspect, at least a portion of the transmitting sensor chip and at least a portion of the receiving sensor chip are within the range of the second roller pair in the direction normal to the surface of the medium at the nip position of the second roller pair, thereby reducing the device dimensions in the direction normal to the surface of the medium at the nip position of the second roller pair.

[0012] A third aspect is a dependent aspect of the first aspect, characterized in that the amplifier and the shielding member are provided on the receiving board on the opposite side to the side on which the receiving sensor chip is provided.

[0013] According to this aspect, since the amplifier and the shielding member are provided on the opposite side of the receiving board from the side on which the receiving sensor chip is provided, both sides of the receiving board can be effectively utilized, making it easier to miniaturize the receiving board, thereby reducing the dimensions of the device. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to the second aspect.

[0014] The fourth aspect is a dependent aspect of the first aspect, characterized in that a connector is provided on the surface of the receiving substrate opposite to the surface facing the receiving sensor chip, and the amplifier and the shielding member are arranged on the surface of the receiving substrate on which the connector is provided.

[0015] According to this aspect, the amplifier and the shielding member are disposed in the space created by the arrangement of the connector, so that the dimensions of the device can be reduced. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to the second aspect.

[0016] The fifth aspect is a dependent aspect of the first aspect, characterized in that, in the receiving board, the amplifier is arranged on the surface on which the receiving sensor chip is provided, and the shielding member covers the receiving sensor chip in addition to the amplifier.

[0017] According to this aspect, the shielding member covers the receiving sensor chip in addition to the amplifier, and by covering the amplifier and the receiving sensor chip with the same shielding member, it is possible to reduce the dimensions of the device while also preventing costs from increasing. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to the second aspect.

[0018] A sixth aspect is a dependent aspect of the first aspect, characterized in that at least a portion of the receiving substrate and at least a portion of the shielding member are within the range of the first roller pair in a direction normal to the surface of the medium at the nip position of the first roller pair, or are within the range of the second roller pair in a direction normal to the surface of the medium at the nip position of the second roller pair.

[0019] According to this aspect, at least a portion of the receiving substrate and at least a portion of the shielding member are within the range of the first roller pair in the direction normal to the surface of the medium at the nip position of the first roller pair, or are within the range of the second roller pair in the direction normal to the surface of the medium at the nip position of the second roller pair, thereby reducing the device dimensions in the direction normal to the surface of the medium at the nip position of the first roller pair or the second roller pair. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to any of the second to fifth aspects.

[0020] A seventh aspect is an aspect dependent on the first aspect, characterized in that the first axis is inclined with respect to the surface of the medium passing between the transmitting sensor chip and the receiving sensor chip, and when calibrating the ultrasonic detection unit, ultrasonic waves are received by the receiving sensor chip while a bias voltage is applied to the receiving sensor chip, and the received signal is amplified by the amplifier.

[0021] According to this aspect, when a piezoelectric element is used for the receiving sensor chip, variations in the polarization direction of the piezoelectric element are less likely to occur, an efficient amplitude can be obtained, and an appropriate receiving signal can be output. It should be noted that this aspect is not limited to the first aspect, but may be subordinate to any of the second to sixth aspects.

[0022] The eighth aspect is a dependent aspect of the seventh aspect, characterized in that the first axis is inclined with respect to the surface of the medium passing between the transmitting sensor chip and the receiving sensor chip, and when detecting a double feed of media using the ultrasonic detection unit, the receiving sensor chip receives ultrasonic waves while a bias voltage is applied to the receiving sensor chip, and the received signal is amplified by the amplifier.

[0023] According to this aspect, when a piezoelectric element is used for the receiving sensor chip, variations in the polarization direction of the piezoelectric element are less likely to occur, an efficient amplitude can be obtained, and an appropriate receiving signal can be output.

[0024] The image reading device of the ninth aspect is characterized by comprising the medium conveying device of any of the first to eighth aspects and a reading unit located downstream of the second roller pair in the conveying direction and configured to read an image on the medium. According to this aspect, the image reading device can achieve the effects of any one of the first to eighth aspects described above.

[0025] The present invention will be specifically described below. In the following, as an example of an image reading device, a scanner 1 capable of reading at least one of a first side S1 and an opposite second side S2 of a document P, which is an example of a medium, is taken as an example. The scanner 1 is a so-called sheet-fed type scanner that reads the document P while moving it between a first reading unit 32 and a second reading unit 33, which will be described later. In this specification, the document P includes not only sheet-shaped documents but also card-shaped documents and booklet-shaped documents. The scanner 1 can be regarded as a medium conveying device 100 from the viewpoint of conveying a document P, which is an example of a medium. In this case, the scanner 1 includes the medium conveying device 100, and a first reading unit 32 and a second reading unit 33, which will be described later.

[0026] In the XYZ coordinate system shown in each figure, the X axis direction is the width direction of the device and also the width direction of the original, the Y axis direction is the depth direction of the device, and the Z axis direction is the vertical direction. In this embodiment, the +Y direction is the direction from the rear to the front of the device, and the -Y direction is the direction from the front to the rear of the device. Also, the left direction as viewed from the front of the device is the +X direction, and the right direction is the -X direction. In the following description, the direction in which the document P is transported may be referred to as "downstream," and the opposite direction may be referred to as "upstream."

[0027] <Scanner Overview> 1, the scanner 1 includes a device main body 2 and a device support part 6 that supports the device main body 2. The device support part 6 is placed on a mounting surface GS of the device. The mounting surface GS is, for example, a surface parallel to a horizontal plane. The device main body 2 is configured to include a first unit 3, a second unit 4, and a third unit 5.

[0028] The second unit 4 and the third unit 5 are rotatable relative to the first unit 3 around a rotation axis (not shown) parallel to the X-axis direction. The second unit 4 and the third unit 5 can rotate integrally relative to the first unit 3 around the rotation axis. Reference symbol 8a in FIG. 1 indicates an unlocking portion. The user can unlock the second unit 4 and the third unit 5 relative to the first unit 3 by sliding the unlocking portion 8a in the -X direction. Rotating the second unit 4 and the third unit 5 relative to the first unit 3 exposes a portion of the document transport path (see FIG. 4). In particular, opening the second unit 4 relative to the first unit 3 exposes the upstream feed path R0, downstream feed path R1, and reading transport path R2, which will be described later.

[0029] The third unit 5 can rotate about a rotation axis (not shown) parallel to the X-axis direction relative to the first unit 3 and the second unit 4. By rotating the third unit 5 relative to the second unit 4, a U-turn discharge path R3 (see FIG. 2) downstream from the reading conveyance path R2 (described later) can be exposed. In other words, the U-turn discharge path R3 is formed between the third unit 5 and the second unit 4.

[0030] Furthermore, the third unit 5 is held relative to the second unit 4 by a snap-fit ​​structure not shown, and when the user applies external force to the third unit 5, the third unit 5 is released from its position relative to the second unit 4, allowing the third unit 5 to be opened.

[0031] The device main body 2 is rotatable around the main body rotation axis 6c (see FIG. 2) relative to the main body support part 6, and in this embodiment, the device main body 2 can hold two positions by rotating. The position of the device main body 2 shown in FIG. 2 is one of the two positions, and is the normal reading position. Note that the device main body 2 can take a booklet reading position (not shown) by rotating from this normal reading position so that the reading transport path R2 approaches horizontal.

[0032] 1, an operation unit 7 made up of a plurality of operation buttons is provided on the front of the device. In this embodiment, the plurality of operation buttons are made up of operation buttons 7a, 7b, and 7c, and user operations are accepted by these buttons.

[0033] <Scanner document transport path> Next, the document transport path in the scanner 1 will be described with reference to Fig. 2. In Fig. 2, the thick dashed line indicates the transport path along which the document P is transported. Reference symbol R0 denotes a conveying path upstream of the first roller pair 13, and is hereinafter referred to as an upstream feeding path R0. Reference symbol R1 denotes a conveying path between the first roller pair 13 and the second roller pair 16, which will be hereinafter referred to as a downstream feeding path R1. The reference symbol R2 denotes a transport path between the second roller pair 16 and the third roller pair 20, and is hereinafter referred to as the reading transport path R2. The reading transport path R2 is a transport path facing the first reading unit 32 and the second reading unit 33, which will be described later. The first unit 3 constitutes the upstream feeding path R0, the downstream feeding path R1, and the lower side of the reading transport path R2, and the second unit 4 constitutes the upstream feeding path R0, the downstream feeding path R1, and the upper side of the reading transport path R2. Further, the reference symbol R3 denotes a conveyance path that reverses upward from the third roller pair 20, and is hereinafter referred to as a U-turn discharge path R3. The U-turn discharge path R3 is formed between the second unit 4 and the third unit 5.

[0034] The normal reading position of the device body 2 (FIG. 2) is a position in which the reading transport path R2 is connected to the U-turn discharge path R3 by the flap 35. In the booklet reading position (not shown) of the device body 2, the flap 35 is in the position indicated by the two-dot chain line, the reading transport path R2 is not connected to the U-turn discharge path R3, and the document P is discharged from the reading transport path R2 in a diagonally downward direction including a +Y direction component and a -Z direction component. The normal reading position is suitable for reading a sheet-like document P, that is, a document P that has low rigidity and is easily bent. The booklet reading position is suitable for reading a document P that has high rigidity and is not easily bent, such as a plastic card or booklet.

[0035] The document transport path will be further explained below. The document P to be fed is supported in an inclined position by the document support section 11 and the document support 9. When multiple documents P are supported on the document support section 11, the top document P is sent downstream by the feed roller 14. The document support section 11 is formed in the upper opening / closing section 10. The upper opening / closing section 10 is rotatable around a rotation axis (not shown), and opens and closes the feed port by rotating. The document support 9 can be stored in the upper opening / closing unit 10 or deployed from the upper opening / closing unit 10. Fig. 1 shows the state in which the upper opening / closing unit 10 is closed, and Fig. 2 shows the state in which the upper opening / closing unit 10 is open and the document support 9 is deployed. The upper opening / closing unit 10 and the document support 9 constitute a first unit 3. The scanner 1 employs a so-called center feeding system, and the center position of the document P in the X-axis direction, i.e., in the width direction, is consistent regardless of the size of the document P.

[0036] The feeding roller 14 and the separation roller 15 constitute a first roller pair 13 . The feed roller 14 is provided in the second unit 4. The feed roller 14 receives power from a transport motor 47 (see FIG. 3) and rotates. A separation roller 15 is provided in the first unit 3 at a position opposite the feed roller 14. A rotational torque is applied to the separation roller 15 by a torque limiter 15b (see FIG. 6), and the separation roller 15 prevents multiple documents P from being fed. In addition, in this embodiment, the feed roller 14 is provided above the original documents P placed on the original document support section 11, and the topmost original document P is fed first, but the feed roller 14 may also be provided below the original documents P placed on the original document support section 11, and the bottommost original document P is fed first.

[0037] An ultrasonic detector 50 is provided on the downstream feeding path R1 downstream of the first roller pair 13. The ultrasonic detector 50 includes a transmitting unit 50A and a receiving unit 50B that are arranged opposite each other across the downstream feeding path R1. The controller 80 (see FIG. 3) can detect double feeding of the document P based on a signal transmitted from the receiving unit 50B. In FIG. 2, the positions, sizes, and shapes of the transmitting unit 50A and the receiving unit 50B are shown conceptually, and details thereof will be explained again later with reference to FIG. 4 and subsequent figures. In this embodiment, the transmitting unit 50A is arranged below the downstream feed path R1 and the receiving unit 50B is arranged above the downstream feed path R1, but this is not limited to this, and the receiving unit 50B may be arranged below the downstream feed path R1 and the transmitting unit 50A may be arranged above the downstream feed path R1.

[0038] A second roller pair 16 is provided downstream of the feed roller 14 and the separation roller 15. The second roller pair 16 is composed of a second lower roller 17 provided in the first unit 3 and a second upper roller 18 provided in the second unit 4. The second upper roller 18 is provided so as to be able to move toward and away from the second lower roller 17, and is pressed toward the second lower roller 17 by a pressing member (not shown), such as a coil spring. This causes the second upper roller 18 to move toward and away from the second lower roller 17 depending on the thickness of the document P being transported. The second lower roller 17 and the second upper roller 18 are both rotated by power received from a transport motor 47 (see FIG. 3). When the second unit 4 is closed relative to the first unit 3, the second lower roller 17 and the second upper roller 18 come into contact with each other. When the second unit 4 is opened relative to the first unit 3, the second upper roller 18 moves away from the second lower roller 17.

[0039] A first reading unit 32 and a second reading unit 33 are disposed facing each other downstream of the second roller pair 16. The first reading unit 32 is provided in the first unit 3, and the second reading unit 33 is provided in the second unit 4. The first reading unit 32 reads the bottom surface, i.e., the first surface S1, of the document P supported by the document support unit 11, and the second reading unit 33 reads the top surface, i.e., the second surface S2, of the document P supported by the document support unit 11. The second reading unit 33 is provided so as to be able to move forward and backward relative to the first reading unit 32, and is pressed toward the first reading unit 32 by a pressing spring 34, which is an example of a pressing member. This causes the second reading unit 33 to move forward and backward relative to the first reading unit 32 depending on the thickness of the document P being transported. In this embodiment, the first reading unit 32 and the second reading unit 33 are configured as contact image sensor modules (CISMs).

[0040] A third roller pair 20 is provided downstream of the first reading unit 32 and the second reading unit 33. The third roller pair 20 is composed of a third lower roller 21 provided in the first unit 3 and a third upper roller 22 provided in the second unit 4. The third upper roller 22 is provided so as to be able to move forward and backward relative to the third lower roller 21, and is pressed against the third lower roller 21 by a pressing member (not shown), for example a coil spring. The third lower roller 21 and the third upper roller 22 are both rotated by power received from a conveyance motor 47 (see FIG. 3). When the second unit 4 is closed relative to the first unit 3, the third lower roller 21 and the third upper roller 22 come into contact with each other. When the second unit 4 is opened relative to the first unit 3, the third upper roller 22 moves away from the third lower roller 21.

[0041] A flap 35 is provided downstream of the third roller pair 20. The flap 35 switches the document transport path as described above by rotating. In this embodiment, the flap 35 is configured to rotate in conjunction with the change in position of the device main body 2. In this embodiment, the flap 35 is rotated in conjunction with the change in position of the device main body 2 by a linkage mechanism (not shown), for example a cam mechanism, which mechanically rotates the flap in conjunction with the position of the device main body 2. However, the flap 35 may also be configured to rotate by a solenoid (not shown). In this case, the control unit 80 (see FIG. 3), which performs various controls, drives the solenoid to rotate the flap 35 based on detection information from a position detection sensor (not shown).

[0042] A fourth roller pair 24 and a fifth roller pair 28 are provided on the U-turn discharge path R3. The fourth roller pair 24 is composed of a fourth drive roller 25 provided in the third unit 5 and a fourth driven roller 26 provided in the second unit 4. The fourth driven roller 26 is provided so as to be able to move toward and away from the fourth drive roller 25, and is pressed toward the fourth drive roller 25 by a pressing member (not shown), such as a coil spring. This allows the fourth driven roller 26 to move toward and away from the fourth drive roller 25 depending on the thickness of the document P being transported. The fourth drive roller 25 is driven by a transport motor 47 (see FIG. 3). The fourth driven roller 26 is a roller that is driven to rotate.

[0043] The fifth roller pair 28 is composed of a fifth drive roller 29 provided in the third unit 5 and a fifth driven roller 30 provided in the second unit 4. The fifth driven roller 30 is provided so as to be able to move toward and away from the fifth drive roller 29, and is pressed toward the fifth drive roller 29 by a pressing member (not shown), such as a coil spring. This causes the fifth driven roller 30 to move toward and away from the fifth drive roller 29 depending on the thickness of the document P being transported. The fifth drive roller 29 is driven by a transport motor 47 (see FIG. 3). The fifth driven roller 30 is a roller that is rotated by the transport motor 47.

[0044] When the third unit 5 is closed relative to the second unit 4, the fourth drive roller 25 and the fourth driven roller 26 come into contact, and the fifth drive roller 29 and the fifth driven roller 30 also come into contact. When the third unit 5 is opened relative to the second unit 4, the fourth drive roller 25 and the fourth driven roller 26 move apart, and the fifth drive roller 29 and the fifth driven roller 30 also move apart. The document P discharged from the U-turn discharge path R3 is discharged obliquely upward including a −Y direction component by the fifth roller pair 28, and is supported in an inclined posture by the upper surface 4a of the second unit 4.

[0045] 2 indicates the direction normal to the first surface S1 and the opposite second surface S2 of the document P at the document nip position of the first roller pair 13. In most cases, the first surface S1 and the opposite second surface S2 of the document P are parallel, and therefore, hereinafter, when there is no need to distinguish between them, they will be collectively referred to as document surface S. The arrow Da2 indicates the normal direction to the document surface S of the document P that passes between the transmitting unit 50A and the receiving unit 50B of the ultrasonic detection section 50. An arrow Da3 indicates the normal direction to the document surface S at the document nip position of the second roller pair 16. The arrow Da4 indicates the normal direction to the document surface S of the document P passing between the first reading unit 32 and the second reading unit 33. An arrow Da5 indicates the normal direction to the document surface S at the document nip position of the third roller pair 20. In this embodiment, the differences between the normal directions Da1, Da2, Da3, Da4, and Da5 are slight, and as an example, the difference between the maximum angle and the minimum angle is within 5°. Therefore, hereinafter, when there is no need to distinguish between the normal directions, they will be referred to as the normal direction Da. 2, the direction indicated by the arrow Fp is perpendicular to the normal direction Da and indicates the direction in which the document P is transported. Hereinafter, this direction will be referred to as the transport direction Fp. In addition, in Figure 4 and subsequent figures, the X-Fp-Da coordinate system will be used in some cases.

[0046] <Scanner control system> Next, the control system of the scanner 1 will be described with reference to FIG. The control unit 80 includes a calculation unit 81 configured with a CPU (Central Processing Unit) and the like, and a storage unit 85 configured with a non-volatile memory or a volatile memory. The first reading unit 32, the second reading unit 33, the transport motor 47, and the ultrasonic detection unit 50 are connected to and controlled by the control unit 80. The transport motor 47 is the drive source for the feed roller 14, the second lower roller 17, the second upper roller 18, the third lower roller 21, the third upper roller 22, the fourth drive roller 25, and the fifth drive roller 29.

[0047] The control unit 80 is connected to an interface unit 86, and receives various data and signals input from an external device 87 such as a personal computer, and outputs the read data read by the scanner 1 to the external device 87.

[0048] The storage unit 85 stores various data and programs for controlling the scanner 1. The calculation unit 81 reads and executes various programs stored in the storage unit 85, thereby functioning as a transport control unit 82, a reading control unit 83, a multiple feed determination unit 84, and the like.

[0049] The transport control unit 82 controls the transport motor 47 to rotate the above-mentioned rollers, thereby feeding, transporting, and discharging the document P. The reading control unit 83 controls the first reading unit 32 and the second reading unit 33 while the document P is being transported, and causes them to read the image of the document P.

[0050] The multifeed determining section 84 is a state detecting section that detects the state of the document P, and in this embodiment, determines whether the document P has been multifed based on a reception signal input from a receiving circuit 59 (described later). Specifically, when the voltage value of the received signal is smaller than a predetermined threshold, it is determined that the document P has been multi-fed. When the multi-feed determination unit 84 determines that a multi-feed has occurred, the transport control unit 82 stops transporting the document P.

[0051] <Basic configuration of ultrasonic detection unit> Next, the basic configuration of the ultrasonic detection unit 50 will be described. 22, the ultrasonic detection unit 50 is configured to include a pair of ultrasonic elements. One of the pair of ultrasonic elements is a transmitting sensor chip 53, which transmits ultrasonic waves. The other of the pair of ultrasonic elements is a receiving sensor chip 56, which receives ultrasonic waves. The transmitting sensor chip 53 and the receiving sensor chip 56 are arranged opposite to each other on a sensor central axis Lx, which is an example of a first axis, with the document P conveyed along the downstream feeding path R1 sandwiched therebetween.

[0052] In this ultrasonic detection unit 50, ultrasonic waves are emitted from the transmitting sensor chip 53 toward the first surface S1 of the document P being fed. The ultrasonic waves emitted from the transmitting sensor chip 53 are input to the document P, and the ultrasonic waves that pass through the document P are received by the receiving sensor chip 56. When the ultrasonic waves are received by the receiving sensor chip 56, a reception signal corresponding to the sound pressure of the received ultrasonic waves is output, and whether the document P is being fed multiple times is determined based on the signal strength of this reception signal.

[0053] The sensor central axis Lx is an axis passing through the center of the transmitting sensor chip 53 and the center of the receiving sensor chip 56, and is the direction of transmission and reception of ultrasonic waves. The sensor central axis Lx is perpendicular to the transmitting surface 53a, which is the top surface of the transmitting sensor chip 53, and the receiving surface 56a, which is the top surface of the receiving sensor chip 56. The sensor central axis Lx is inclined at an angle β with respect to the document surface S of the document P. Here, when the sensor central axis Lx coincides with the normal direction of the document surface S, that is, when the angle β is 90°, there is a risk that the ultrasonic waves transmitted from the transmitting sensor chip 53 will be multiply reflected between the document P and the transmitting sensor chip 53. Also, there is a risk that the ultrasonic waves that have passed through the document P will be multiply reflected between the receiving sensor chip 56 and the document P. In this case, in addition to the ultrasonic waves that have passed through the document P from the transmitting sensor chip 53 and are received by the receiving sensor chip 56, the receiving sensor chip 56 will also receive ultrasonic waves that have been multiply reflected between the document P and the transmitting sensor chip 53 and ultrasonic waves that have been multiply reflected between the receiving sensor chip 56 and the document P, and therefore accurate double feed detection will not be possible.

[0054] In contrast, by tilting the sensor central axis Lx with respect to the normal to the document surface S of the document P, reception of unnecessary ultrasonic components such as multiply reflected ultrasonic waves can be reduced, enabling highly accurate detection of double feed. The angle β can be set to a value between 60° and 80°, and is set to 70° in this embodiment.

[0055] Note that if the area of ​​the transmitting surface 53a of the transmitting sensor chip 53 is small, the beam diameter of the ultrasonic waves will be small. In this case, if the distance between the transmitting sensor chip 53 and the receiving sensor chip 56, i.e., the distance along the sensor central axis Lx, is short, the drop in sound pressure of the ultrasonic waves will be large when the transmitting sensor chip 53 is displaced from the sensor central axis Lx due to an installation error. Similarly, if the area of ​​the receiving surface 56a of the receiving sensor chip 56 is small, the drop in sound pressure will be large when the transmitting sensor chip 53 is displaced from the sensor central axis Lx. Therefore, it is preferable to ensure a certain distance between the transmitting sensor chip 53 and the receiving sensor chip 56, but if the distance between the transmitting sensor chip 53 and the receiving sensor chip 56 is too long, this will also result in a drop in sound pressure. In this embodiment, in view of the above, the distance along the sensor central axis Lx between the transmitting sensor chip 53 and the receiving sensor chip 56, i.e., the sensor-to-sensor distance, is set in the range of 15.0 mm to 30.0 mm, and is set to 24.9 mm as an example.

[0056] <Sensor chip configuration> The configuration of the ultrasonic detection unit 50 will be further described. As shown in FIG. 3, the transmitting substrate 52 is provided with a transmitting circuit 58 that controls the transmitting sensor chip 53, and the receiving substrate 55 is provided with a receiving circuit 59 that controls the receiving sensor chip .

[0057] The configuration of the transmitting sensor chip 53 will now be described with reference to FIG. The transmitting sensor chip 53 is configured to include a base substrate 213 , an element substrate 210 , and a piezoelectric element 220 . The element substrate 210 includes a substrate main body 211 and a diaphragm 212 provided on one surface of the substrate main body 211. In the following description, the substrate thickness direction of the element substrate 210 is referred to as the G direction. The G direction is the direction in which ultrasonic waves are transmitted, and is parallel to the sensor central axis Lx. Substrate main body 211 is a substrate provided on diaphragm 212, and is made of a semiconductor substrate such as Si. Substrate main body 211 is provided with opening 211A that penetrates substrate main body 211 along the G direction. The diaphragm 212 is supported by a base substrate 213. The diaphragm 212 and the base substrate 213 are fixed by adhesive. A space is provided between the base substrate 213 and the diaphragm 212 in which a piezoelectric element 220 is disposed. The diaphragm 212 may be fixed to the base substrate 213 in a stacked state.

[0058] The diaphragm 212 is made of SiO2 or a laminate of SiO2 and GrO2, and is provided on the -G side of the substrate main body 211. The diaphragm 212 closes the -G side of the opening 211A. The portion of the diaphragm 212 that overlaps with the opening 211A when viewed from the G direction forms the vibrating portion 212A.

[0059] Piezoelectric element 220 is provided on vibration plate 212 at a position overlapping each vibration portion 212A when viewed from the G direction. Piezoelectric element 220 is configured by laminating a first electrode 221, a piezoelectric film 222, and a second electrode 223 in this order on vibration plate 212.

[0060] Here, one vibration part 212A and a piezoelectric element 220 provided on the vibration part 212A constitute one ultrasonic transducer Tr. Although not shown in the figures, in this embodiment, such ultrasonic transducers Tr are arranged in a two-dimensional array structure to constitute the transmitting sensor chip 53. The transmitting circuit 58 (see FIG. 3) is electrically connected to each ultrasonic transducer Tr of the transmitting sensor chip 53, and generates a drive signal for driving each ultrasonic transducer Tr.

[0061] In the transmitting sensor chip 53, a pulse wave voltage of a predetermined frequency is applied between the first electrode 221 and the second electrode 223 of each ultrasonic transducer Tr, causing the piezoelectric film 222 to expand and contract. This causes the vibrating part 212A to vibrate at a frequency according to the opening width of the opening 211A, etc., and ultrasonic waves are transmitted from the vibrating part 212A toward the +G side along the sensor central axis Lx. In other words, the +G side surface of the element substrate 210 becomes the ultrasonic wave transmission surface 53a of the transmitting sensor chip 53.

[0062] The base substrate 213 of the transmitting sensor chip 53 is attached to the transmitting substrate 52 with a non-conductive adhesive via a resist. At least one of a chip tilt prevention pad (not shown) for preventing the transmitting sensor chip 53 from tilting relative to the transmitting substrate 52, a positioning mark (not shown) for the transmitting sensor chip 53 relative to the transmitting substrate 52, and an adhesive leakage prevention part (not shown) for preventing the non-conductive adhesive from spilling out is provided on the transmitting substrate 52. Furthermore, the transmitting sensor chip 53 is attached to the transmitting substrate 52 with silver paste at a position different from that of the chip tilt prevention pad (not shown), and the chip tilt prevention pad (not shown) is not used for electrical conduction.

[0063] Although the configuration of the receiving sensor chip 56 is not shown, the receiving sensor chip 56 has the same configuration as the transmitting sensor chip 53 described above. In this case, the +G side surface of the element substrate 210 serves as the ultrasonic wave receiving surface 56a of the receiving sensor chip 56. When ultrasonic waves reach the ultrasonic transducer Tr, the diaphragm 212 vibrates in response to the sound pressure of the ultrasonic waves. The vibration of the diaphragm 212 deforms the piezoelectric film 222, generating a potential difference between the first electrode 221 and the second electrode 223. As a result, a reception signal corresponding to the sound pressure of the received ultrasonic waves is output from the first electrode 221 of the ultrasonic transducer Tr. In other words, the ultrasonic waves are detected. A general circuit for processing the received signal input by receiving ultrasonic waves can be used as the receiving circuit 59 (FIG. 3) that processes the received signal. For example, the receiving circuit 59 can be configured with a band-pass filter, an amplifier, a sample-and-hold circuit, a comparator, etc. (not shown). Therefore, in view of the function of the amplifier, the receiving circuit 59 can also be called an amplifier. The ultrasonic detection unit 50 according to this embodiment has a voltage application unit 51 that applies a bias voltage to the receiving sensor chip 56. The voltage application unit 51 may be mounted on a dedicated board, may be mounted on the receiving board 55, or may be part of the control unit 80.

[0064] During calibration, the ultrasonic detection unit 50 receives ultrasonic waves through the receiving sensor chip 56 with a bias voltage applied to the receiving sensor chip 56, and the received signal is amplified by the receiving circuit 59. Calibration involves emitting ultrasonic waves from the transmitting sensor chip 53 in the absence of a document P, and adjusting the output of the transmitted ultrasonic waves based on the sound pressure of the ultrasonic waves received by the receiving sensor chip 56. When a piezoelectric element 220 is used in the receiving sensor chip 56, applying a bias voltage to the receiving sensor chip 56 reduces the variation in the polarization direction of the piezoelectric element 220, resulting in an efficient amplitude and enabling an appropriate receiving signal to be output.

[0065] Similarly, when detecting double feeding of documents P, the ultrasonic detection unit 50 receives ultrasonic waves through the receiving sensor chip 56 with a bias voltage applied to the receiving sensor chip 56, and the received signal is amplified by the receiving circuit 59. As a result, even when detecting double feeding of documents P, variations in the polarization direction of the piezoelectric element 220 are less likely to occur, an efficient amplitude can be obtained, and an appropriate received signal can be output.

[0066] <Configuration of transmitting sensor unit and receiving sensor unit> Next, the configurations of the transmitting unit 50A and the receiving unit 50B will be described. 4 shows a state in which the second unit 4 is opened relative to the first unit 3. When the second unit 4 is opened relative to the first unit 3, the inside of the first unit 3 and the inside of the second unit 4 are exposed. A transmission-side path forming member 36 is provided inside the first unit 3, and when the second unit 4 is opened relative to the first unit 3, the transmission-side path forming member 36 is exposed. A receiving path forming member 39 is provided inside the second unit 4, and when the second unit 4 is opened relative to the first unit 3, the receiving path forming member 39 is exposed. The transmitting path forming member 36 and the receiving path forming member 39 form a part of the upstream feeding path R0, a downstream feeding path R1, and a reading transport path R2.

[0067] As shown in Fig. 5, a cover 37 is provided on the transmission-side path forming member 36. The cover 37 is detachably provided on the transmission-side path forming member 36 so that it can be in an attached state as shown in Fig. 5 and Fig. 6, and in a removed state as shown in Fig. 7. The cover 37 is attachable to the transmission-side path forming member 36 by a snap-fit ​​structure (not shown). A circular opening 37a is formed in the cover 37, and the sensor central axis Lx of the ultrasonic detection unit 50 passes through the vicinity of the center of the opening 37a. A part of a first protective member 70, which will be described later, is exposed inside the opening 37a.

[0068] A transmitting unit 50A is provided inside the cover 37, and when the cover 37 is removed, the transmitting unit 50A is exposed as shown in Fig. 7. Note that even when the cover 37 is attached, a portion of the transmitting unit 50A is exposed, as shown in Fig. 6, but when the cover 37 is opened, an even larger portion of the transmitting unit 50A is exposed. When the cover 37 is attached as shown in Fig. 6, a portion of a first wall portion 60b of a transmitting board holder 60, which will be described later, is exposed.

[0069] Furthermore, a roller holding member 38 that holds the separation roller 15 is provided inside the cover 37, and when the cover 37 is removed, the roller holding member 38 can be removed, and thus the separation roller 15 can be replaced together with the roller holding member 38. In FIG. 6, reference numeral 15a denotes a rotation shaft of the separation roller 15, and reference numeral 15b denotes a torque limiter that applies separation torque to the separation roller 15.

[0070] In Figure 5, symbol Ba1 is the distance between the center of the rotation axis of the separation roller 15 and the center of the rotation axis of the second lower roller 17, i.e., the inter-axis distance, and symbol Ba2 is the distance between the center of the rotation axis of the second lower roller 17 and the center of the rotation axis of the third lower roller 21, i.e., the inter-axis distance. In this embodiment, the inter-axis distance Ba1 is shorter than the inter-axis distance Ba2. In other words, the path length of the downstream feeding path R1 is shorter than the path length of the reading transport path R2. In this embodiment, the center distance Ba1 is 29.1 mm, and the center distance Ba2 is 34.0 mm.

[0071] 8, a transport motor 47 and a main board 48 are provided on the −Da direction side of the transmission-side path forming member 36. The transport motor 47 is provided at the −X direction end on the rear side of the transmission-side path forming member 36. The main board 48 constitutes the above-mentioned control unit 80. Between the main board 48 and the transmission-side path forming member 36, a transmission unit 50A is provided as shown in FIG. The configuration of the transmitting unit 50A will be described in detail later, but the transmitting unit 50A has a transmitting board holder 60 as its base, and this transmitting board holder 60 is fixed to the transmitting side path forming member 36 by screws 61, 61.

[0072] 10, a circular opening 39a is formed in the receiving-side path forming member 39, and the sensor central axis Lx of the ultrasonic detection unit 50 is configured to pass through the vicinity of the center of the opening 39a. A part of a second protective member 73, which will be described later, is exposed inside the opening 39a. In addition, in Figure 10, symbol Bb1 is the distance between the center of the rotation axis of the feed roller 14 and the center of the rotation axis of the second upper roller 18, i.e., the inter-axial distance, and symbol Bb2 is the distance between the center of the rotation axis of the second upper roller 18 and the center of the rotation axis of the third upper roller 22, i.e., the inter-axial distance. In this embodiment, the inter-axis distance Bb1 is shorter than the inter-axis distance Bb2, ie, the path length of the downstream feeding path R1 is shorter than the path length of the reading transport path R2. In this embodiment, the center distance Bb1 is 30.0 mm, and the center distance Bb2 is 34.0 mm.

[0073] As shown in FIG. 11, a receiving unit 50B is provided on the +Da side of the receiving side path forming member 39. The configuration of the receiving unit 50B will be described in detail later, but the receiving unit 50B has a receiving board holder 62 as its base, and a fixed portion 62j, which is a component of this receiving board holder 62, is fixed to the receiving-side path forming member 39 by a receiving-side holder fixing screw 63. Note that reference numeral 39b denotes a positioning portion provided on the receiving-side path forming member 39, and the positioned portion 62k is positioned relative to the receiving-side path forming member 39 by fitting a hole 62e provided on the positioned portion 62k of the receiving board holder 62 into the positioning portion 39b. As a result of the above, the receiving board holder 62 is positioned relative to the receiving side path forming member 39 and fixed.

[0074] Next, the configurations of the transmitting unit 50A and the receiving unit 50B will be further explained with reference to FIG. 12 and subsequent figures. 12, the ultrasonic detection unit 50 is disposed in the space between the first roller pair 13 and the second roller pair 16. Arranged along the conveying direction Fp are the separation roller 15 constituting the first roller pair 13, the transmitting unit 50A, the second lower roller 17 constituting the second roller pair 16, and the third lower roller 21 constituting the third roller pair 20, in that order. Also arranged along the conveying direction Fp are the feed roller 14 constituting the first roller pair 13, the receiving unit 50B, the second upper roller 18 constituting the second roller pair 16, and the third upper roller 22 constituting the third roller pair 20, in that order.

[0075] As shown in FIGS. 13 and 14, the transmission unit 50A is configured by providing a transmission board 52 and a first protective member 70 in a transmission board holder 60. Similarly, the receiving unit 50B is configured by providing a receiving board 55 and a second protective member 73 on a receiving board holder 62.

[0076] 17 and 18, the transmission board holder 60 has screw holes 60e in the screw fixing portions 60j, 60k, and the screws 61 described with reference to Fig. 9 are passed through these screw holes 60e. Between the screw fixing portions 60j and 60k, a fixing portion 60a is formed so as to be positioned in the +Da direction from the screw fixing portions 60j, 60j. The fixing portion 60a is a portion for fixing the first protective member 70, and has a first opening 60f formed in the center (see Figs. 17, 18, and 22). The first opening 60f is formed so that the sensor central axis Lx of the ultrasonic detection unit 50 passes near the center of the first opening 60f.

[0077] Protective member positioning portions 60c, 60c are formed on the surface of the fixed portion 60a. The first protective member 70 is held by a first holding member 71, as shown in Fig. 19, and recesses 71a, 71a are formed in the first holding member 71. The recesses 71a, 71a fit into the protective member positioning portions 60c, 60c, thereby positioning the first holding member 71, i.e., the first protective member 70, with respect to the fixed portion 60a.

[0078] A cylindrical protrusion 60m is formed on the back side of the fixing portion 60a as shown in Fig. 18, and a screw hole 60g is formed in the protrusion 60m. Also, a board positioning portion 60d is formed on the back side of the fixing portion 60a as shown in Fig. 14. 15, an opening 52a and a recess 52b are formed in the transmitting board 52. The opening 52a fits over a protrusion 60m of the transmitting board holder 60, and the recess 52b fits over a board positioning portion 60d of the transmitting board holder 60, thereby positioning the transmitting board 52 relative to the transmitting board holder 60. Then, as shown in FIG. 14, the transmitting board fixing screw 54 fits into the screw hole 60g (FIG. 18), thereby fixing the transmitting board 52 to the transmitting board holder 60.

[0079] The transmitting board holder 60 holds the transmitting board 52 so that the transmitting surface 53a of the transmitting sensor chip 53 is inclined at an angle α1 with respect to the document surface S as shown in Fig. 22. As a result, the transmitting surface 53a of the transmitting sensor chip 53 and the receiving surface 56a of the receiving sensor chip 56 are parallel to each other, and the sensor central axis Lx is inclined at an angle β with respect to the document surface S.

[0080] Furthermore, a first wall portion 60b is formed upstream of the fixed portion 60a in the conveying direction Fp, as shown in Figures 13, 14, 17, and 18, and a second wall portion 60h is formed downstream of the fixed portion 60a in the conveying direction Fp. The first wall portion 60b is located in a position that is visible from the outside when the cover 37 is closed as shown in FIG. 6, and serves to protect the transmitting board 52 from foreign matter, liquid, and the like. Although not shown in the drawings, when the first wall portion 60b is viewed from upstream in the conveyance direction Fp, it is positioned so as to overlap with part of the transmitting substrate 52 and the entire transmitting sensor chip 53. In other words, when the first wall portion 60b is viewed from upstream in the conveyance direction Fp, it is positioned so that part of the transmitting substrate 52 and the entire transmitting sensor chip 53 are hidden by the first wall portion 60b.

[0081] Next, the receiving board holder 62 has the fixed portion 62j and the positioned portion 62k described with reference to Fig. 11, and the fixing portion 62a is formed between the fixed portion 62j and the positioned portion 62k so as to be positioned in the -Da direction from the fixed portion 62j and the positioned portion 62k. The fixing portion 62a is a portion for fixing the second protective member 73, and a second opening 62f is formed in the center (see Fig. 22), and the second opening 62f is formed so that the sensor central axis Lx of the ultrasonic detection unit 50 passes near the center of the second opening 62f.

[0082] 14, protective member positioning portions 62c, 62c are formed on the surface of the fixed portion 62a. The second protective member 73 is held by a second holding member 74, and recesses 74a, 74a are formed in the second holding member 74. The recesses 74a, 74a fit into the protective member positioning portions 62c, 62c, thereby positioning the second holding member 74, i.e., the second protective member 73, with respect to the fixed portion 62a.

[0083] As shown in FIG. 13, a protruding board positioning portion 62d is formed on the back side of the fixing portion 62a. A recess 55b is formed in the receiving board 55. The recess 55b fits into the board positioning portion 62d. Although not shown, the receiving board holder 62 is formed with a protrusion and a screw hole similar to the protrusion 60m and screw hole 60g of the transmitting board holder 60, respectively. The receiving board 55 is also formed with an opening similar to the opening 52a of the transmitting board 52 (see FIG. 15). The receiving board 55 is positioned relative to the receiving board holder 62 by fitting this opening with the protrusion of the receiving board holder 62 and fitting the recess 55b of the receiving board 55 with the board positioning portion 62d of the receiving board holder 62. The receiving board 55 is fixed to the receiving board holder 62 by fitting the receiving board fixing screw 57 into the screw hole, as shown in FIG. 13.

[0084] The receiving board holder 62 holds the receiving board 55 so that the receiving surface 56a of the receiving sensor chip 56 is inclined at an angle α1 with respect to the document surface S, as shown in Fig. 22. As a result, the receiving surface 56a of the receiving sensor chip 56 and the transmitting surface 53a of the transmitting sensor chip 53 are parallel to each other, and the sensor central axis Lx is inclined at an angle β with respect to the document surface S.

[0085] As described above, in this embodiment, the transmitting board 52 is fixed to the transmitting-side path forming member 36, which is a member that forms the document transport path, via the transmitting board holder 60, and the receiving board 55 is fixed to the receiving-side path forming member 39, which is a member that forms the document transport path, via the receiving board holder 62. This stabilizes the distance between the document P and the transmitting sensor chip 53, and the distance between the document P and the receiving sensor chip 56, and therefore stabilizes the detected value of the ultrasonic waves.

[0086] Next, the configuration of the transmission board 52 will be described. 13 to 15, the transmitting substrate 52 is a rectangular substrate having short sides E1 and long sides E2, and one of the short sides E1 is formed with the recess 52b as described above. The transmitting substrate 52 is disposed so that the short side E1 is aligned with the conveyance direction Fp. The transmitting sensor chip 53 is fixed in a state in which it is placed on the substrate surface 52d of the transmitting substrate 52, and no other members such as a base are interposed between the transmitting sensor chip 53 and the substrate surface 52d except for the adhesive.

[0087] A connector 52c is provided on the opposite side of the board surface 52d of the transmission board 52, and a transmission side cable 76 (see FIGS. 13 and 14) is connected to this connector 52c. A first enclosing member 65 is provided on the board surface 52d of the transmitting board 52. In this embodiment, the first enclosing member 65 is made of a metal plate and is fixed to the transmitting board 52 with an adhesive. An opening 65a is formed in the first enclosing member 65 so that the sensor central axis Lx of the ultrasonic detection unit 50 passes through the vicinity of the center of the opening 65a. The first enclosing member 65 is provided along the substrate surface 52d as shown in FIG.

[0088] The transmitting board fixing screw 54 includes a head portion with a screwdriver fitting hole, a threaded portion with an external thread, and a tip portion at the end of the external thread. The threaded portion is attached to a mounting portion on the same side of the board surface 52d of the transmitting board 52 as the transmitting sensor chip 53, specifically, to the threaded hole 60g (see FIGS. 18 and 22). Note that the threaded portion may also be attached to a mounting portion, i.e., a threaded hole, on the opposite side of the board surface 52d of the transmitting board 52 from the transmitting sensor chip 53. When the transmitting board 52 is fixed to the transmitting board holder 60, the position of the tip 54a of the transmitting board fixing screw 54 is in the -Da direction in the normal direction Da from the position 65b of the first enclosing member 65 that is furthest in the +Da direction. Furthermore, the direction along the sensor center axis Lx from the transmitting unit 50A toward the receiving unit 50B is defined as the +Lx direction, and the opposite direction is defined as the -Lx direction. When the transmitting board 52 is fixed to the transmitting board holder 60, the position of the tip 54a of the transmitting board fixing screw 54 is located in the +Lx direction relative to the first enclosure member 65. Furthermore, the distance from the board surface 52d of the transmitting board 52 to the first enclosing member 65 is shorter than the length of the threaded portion of the transmitting board fixing screw .

[0089] 16, symbol t0 denotes the total thickness of the transmitting substrate 52 and the transmitting sensor chip 53, symbol t1 denotes the thickness of the transmitting substrate 52, and symbol t2 denotes the thickness of the transmitting sensor chip 53. The thickness t2 of the transmitting sensor chip 53 is thinner than the thickness of the transmitting substrate 52. For example, the thickness of the transmitting substrate 52 may be 0.8 to 1.2 mm, and particularly 1.0 mm. For example, the thickness of the transmitting sensor chip 53 may be 0.5 to 0.7 mm, and particularly 0.578 mm. For example, the distance from the board surface 52d of the transmitting board 52 to the first enclosing member 65 can be set to 1.2 to 1.6 mm, and particularly 1.4 mm.

[0090] Next, the configuration of the receiving board 55 will be described. In this embodiment, as shown in FIGS. 13 and 14, the shape and dimensions of the receiving board 55 are the same as those of the transmitting board 52. That is, the receiving board 55 is a rectangular board having a short side E1 and a long side E2, and is provided so that the short side E1 is aligned with the conveyance direction Fp. The receiving board 55 is provided with a connector 55c, to which a receiving cable 77 is connected.

[0091] The configuration of the receiving board 55 will be further described below with reference to Fig. 30. For convenience of illustration, the receiving board 55 is drawn horizontally in Figs. The receiving sensor chip 56 is fixed in place on the first substrate surface 55d of the receiving substrate 55, and no other components such as a base are interposed between the receiving sensor chip 56 and the first substrate surface 55d, except for adhesive. The first substrate surface 55d is the surface facing the transmitting sensor chip 53, and the reference numeral 55e is the surface opposite to the first substrate surface 55d. The connector 55c is provided on the second substrate surface 55e.

[0092] The first substrate surface 55d is provided with a second enclosing member 67. In this embodiment, the second enclosing member 67 is made of a metal plate and is fixed to the receiving substrate 55 with an adhesive. The second enclosing member 67 has an opening (not shown) similar to the transmitting-side opening 65a shown in Fig. 15. The opening is formed so that the sensor central axis Lx of the ultrasonic detection unit 50 passes near the center of the opening. The second enclosing member 67 is provided along the first substrate surface 55d.

[0093] Next, a receiving circuit 59 is provided on the second substrate surface 55e. The receiving circuit 59 is in the form of a semiconductor chip, and for example, an ASIC (Application Specific Integrated Circuit) is used. The receiving circuit 59 is mounted and fixed on the second substrate surface 55e, and no other members such as a base are interposed between the receiving circuit 59 and the second substrate surface 55e, except for an adhesive. The receiving circuit 59 is covered with a shielding member 91. In this embodiment, the shielding member 91 is made of a metal plate, similar to the second enclosing member 67, in order to obtain an electromagnetic shielding effect. The shielding member 91 is fixed to the second board surface 55e with an adhesive.

[0094] 30, reference symbol t10 denotes the thickness of the receiving substrate 55, which is the same as the thickness t1 (see FIG. 16) of the transmitting substrate 52. Reference symbol t11 denotes the height of the receiving circuit 59 relative to the second substrate surface 55e. Reference symbol t12 denotes the height of the shielding member 91 relative to the second substrate surface 55e. Furthermore, reference symbol t13 denotes the height of the receiving sensor chip 56 relative to the first substrate surface 55d, and reference symbol t14 denotes the height of the second enclosing member 67 relative to the first substrate surface 55d.

[0095] For example, the thickness t10 can be set to 0.8 to 1.2 mm, and particularly 1.0 mm. As an example, the height t11 ​​can be set to 0.9 to 1.3 mm, and particularly 1.1 mm. As another example, the height t12 can be set to 1.8 to 2.2 mm, and particularly 2.0 mm. As another example, the height t13 can be set to 0.5 to 0.7 mm, and in particular, 0.578 mm. As another example, the height t14 can be set to 1.2 to 1.6 mm, and particularly 1.4 mm.

[0096] 22, the receiving board fixing screw 57 includes a head portion with a screwdriver fitting hole, a threaded portion with an external thread, and a tip portion at the end of the external thread. The threaded portion is attached to a mounting portion on the same side of the first board surface 55d of the receiving board 55 as the receiving sensor chip 56, specifically, to the threaded hole 62g. Note that the threaded portion may also be attached to a mounting portion on the opposite side of the first board surface 55d of the receiving board 55 from the receiving sensor chip 56, i.e., to the threaded hole. When the receiving board 55 is fixed to the receiving board holder 62, the position of the tip 57a of the receiving board fixing screw 57 is located in the +Da direction from the position 67b of the second enclosing member 67 that is furthest in the -Da direction in the normal direction Da. Furthermore, when the receiving board 55 is fixed to the receiving board holder 62, the position of the tip 57a of the receiving board fixing screw 57 is located in the -Lx direction from the second enclosing member 67 in the axial direction of the sensor central axis Lx. Furthermore, the distance from the first board surface 55d of the receiving board 55 to the second enclosing member 67 is shorter than the length of the threaded portion of the receiving board fixing screw 57.

[0097] As described above, the transmitting substrate 52 is provided with the first enclosing member 65, which is a member that surrounds the transmitting sensor chip 53 and is a plate-like member that is provided along the transmitting substrate 52. The receiving substrate 55 is provided with the second enclosing member 67, which is a member that surrounds the receiving sensor chip 56 and is a plate-like member that is provided along the receiving substrate 55. This makes it possible to protect the transmitting sensor chip 53 or the receiving sensor chip 56 from external forces. Furthermore, in this embodiment, the first enclosing member 65 and the second enclosing member 67 are made of a metal material, so that the transmitting sensor chip 53 or the receiving sensor chip 56 can be protected from electromagnetic waves.

[0098] As described above, the receiving board 55 has a receiving circuit 59 that amplifies the ultrasonic wave reception signal received by the receiving sensor chip 56, and a shielding member 91 that is provided on the receiving board 55 and covers at least a portion of the receiving circuit 59. The height t13 of the receiving sensor chip 56 relative to the receiving substrate 55 is lower than the height t12 of the shield member 91 relative to the receiving substrate 55. This allows the dimensions of the device to be reduced in a configuration in which the receiving sensor chip 56 and the shield member 91 are provided on the receiving substrate 55. In this embodiment, the shielding member 91 covers the entire receiving circuit 59, but it may cover only a part of the receiving circuit 59. In this embodiment, the height t13 of the receiving sensor chip 56 relative to the receiving substrate 55 is lower than the height t11 ​​of the receiving circuit 59 relative to the receiving substrate 55. In this embodiment, the height t14 of the second enclosing member 67 relative to the receiving board 55 is lower than the height t12 of the shield member 91 relative to the receiving board 55. In this embodiment, the height t12 of the shield member 91 with respect to the receiving substrate 55 is It is lower than the height t15 of the connector 55c relative to the receiving board 55.

[0099] In this embodiment, the receiving circuit 59 and the shielding member 91 are provided on the second substrate surface 55e of the receiving substrate 55, which is opposite to the first substrate surface 55d on which the receiving sensor chip 56 is provided. This allows for effective use of both surfaces of the receiving substrate 55, making it easier to miniaturize the receiving substrate 55. This allows for reduced device dimensions.

[0100] In this embodiment, a connector 55c is provided on the second board surface 55e of the receiving board 55. The receiving circuit 59 and the shield member 91 are disposed on the second board surface 55e of the receiving board 55 where the connector 55c is provided. As a result, the receiving circuit 59 and the shielding member 91 are disposed in the space created by the arrangement of the connector 55c, and the dimensions of the device can be reduced.

[0101] 31, the receiving circuit 59 may be disposed on the first substrate surface 55d of the receiving substrate 55 on which the receiving sensor chip 56 is provided. In this case, the shielding member 91 may cover the receiving sensor chip 56 in addition to the receiving circuit 59. By covering the receiving circuit 59 and the receiving sensor chip 56 with the same shielding member 91 in this way, it is possible to reduce the size of the device and also prevent an increase in costs. When the receiving circuit 59 and the receiving sensor chip 56 are provided on the first substrate surface 55d, the receiving circuit 59 and the receiving sensor chip 56 may of course be covered with separate shielding members as shown in FIG. In addition, in all of the embodiments in Figures 30, 31, and 32, the receiving sensor chip 56 and the receiving circuit 59 are provided on a single receiving substrate 55, but the receiving sensor chip 56 and the receiving circuit 59 may be provided on separate substrates and arranged side by side to achieve an arrangement equivalent to that in Figures 30, 31, and 32.

[0102] <Configuration of the first protective member and the second protective member> Next, the first protective member 70 and the second protective member 73 will be described in detail. In this embodiment, the first protective member 70 and the second protective member 73 are made of the same material, and the second holding member 74 that holds the second protective member 73 is also made of the same material as the first holding member 71 that holds the first protective member 70. Therefore, in the following, we will explain the first protective member 70 and the first holding member 71, and will omit explanations of the second protective member 73 and the second holding member 74.

[0103] In this embodiment, the first protective member 70 is a filter formed in a mesh shape. Figure 20 shows an enlarged view of a portion of the first protective member 70. 20, the first protective member 70 is a filter formed in a mesh shape by intersecting wires 70a. Note that, although Fig. 20 shows an example in which the wires 70a intersect at 90°, the present invention is not limited to this and the wires 70a may intersect at an angle other than 90°. The wire 70a may be made of metals such as copper, iron, brass, or SUS, alloys, or synthetic resins such as nylon or polyester. In this embodiment, polyester is used as an example.

[0104] It is preferable that the diameter of the wire material 70a is less than the wavelength of the ultrasonic waves, thereby preventing the ultrasonic waves from being diffused by the wire material 70a of the first protection member 70. In the first protective member 70, an opening 70b is formed between each pair of adjacent wires 70a. The opening 70b corresponds to a hole that allows ultrasonic waves to pass through. To prevent foreign matter such as paper dust from adhering to or accumulating on the transmitting surface 53a of the transmitting sensor chip 53 and the receiving surface 56a of the receiving sensor chip 56, it is preferable that the width of the opening 70b, i.e., the opening width Wa, be 1 mm or less. However, in this embodiment, the opening width Wa is set to 30 μm or less, for example, 22 μm, so that the cleaning agent does not pass through the opening 70b when the device is cleaned with the cleaning agent. In Figures 12-14 and 19, the first protective member 70 or the second protective member 73 is shown in a mesh-like shape to clearly show that it is a mesh-like member, but the crossing angle of the wires 70a and the opening width Wa are shown for convenience only.

[0105] As described above, the first protective member 70 and the second protective member 73 are mesh-like members, and therefore ultrasonic waves can pass through the first protective member 70 and the second protective member 73 smoothly.

[0106] The opening width Wa of the mesh member is 30 μm or less, so when the device is cleaned with a cleaning agent, the cleaning agent is prevented from adhering to the transmitting sensor chip 53 through the first protective member 70, or from adhering to the receiving sensor chip 56 through the second protective member 73. As a result, the strength of the ultrasonic waves received by the receiving sensor chip 56 is reduced, and problems that lead to false detection can be prevented.

[0107] 19, the above-described first protective member 70 is held by a first holding member 71 having an opening 71b that exposes the first protective member 70. The first protective member 70 is held by the first holding members 71 by being sandwiched between two first holding members 71. Double-sided tape (not shown) is used between the first protective member 70 and the first holding member 71, thereby integrating the first protective member 70 and the first holding member 71. The relationship between the second protection member 73 and the second holding member 74 is the same as the relationship between the first protection member 70 and the first holding member 71 described above.

[0108] Next, the first protective member 70 is held by the transmitting board holder 60 so as to be inclined at an angle α2 with respect to the document surface S, as shown in Figure 22. Similarly, the second protective member 73 is held by the receiving board holder 62 so as to be inclined at an angle α2 with respect to the document surface S. As a result, the angle formed between the first protective member 70 and the second protective member 73 becomes 0°, that is, the first protective member 70 and the second protective member 73 are parallel to each other. In this embodiment, the angle α2 is set to be different from the angle α1, and specifically, the angle α2 is set to be smaller than the angle α1.

[0109] That is, if the angle α2 and the angle α1 are set to the same angle, that is, if the transmitting surface 53a and the first protective member 70 are parallel, multiple reflections of ultrasonic waves will occur between the transmitting surface 53a and the first protective member 70, and accurate double feeding detection may not be possible. The same applies when the receiving surface 56a and the second protective member 73 are parallel. However, since the angle α2 is set to a different angle from the angle α1 as described above, the multiple reflections can be suppressed and double feed detection can be performed appropriately. In this embodiment, as an example, the angle α1 is set to 20°, and the angle α2 is set to 15°.

[0110] The distance between the transmitting surface 53a and the first protective member 70 is also a factor that can cause multiple reflections of ultrasonic waves. That is, if the distance between the transmitting surface 53a and the first protective member 70 is short, multiple reflections of ultrasonic waves will occur, and based on this viewpoint, in this embodiment, the distance between the transmitting surface 53a and the first protective member 70, i.e., the distance along the sensor central axis Lx, is set to 4.0 mm to 6.0 mm, and is set to 4.89 mm, for example.

[0111] The first protective member 70 described above is held by the transmitting board holder 60 together with the transmitting board 52, thereby suppressing variations in the distance between the transmitting sensor chip 53 and the first protective member 70. As a result, multiple reflections of ultrasonic waves between the transmitting sensor chip 53 and the first protective member 70 can be appropriately suppressed. Similarly, the second protective member 73 is held by the receiving substrate holder 62 together with the receiving substrate 55, which reduces variations in the distance between the receiving sensor chip 56 and the second protective member 73. As a result, multiple reflections of ultrasonic waves between the receiving sensor chip 56 and the second protective member 73 can be appropriately reduced.

[0112] The transmission board holder 60 also has a first opening 60f on the sensor central axis Lx that allows ultrasonic waves to pass through, and the first protective member 70 is provided on the surface of the transmission board holder 60 so as to cover the first opening 60f. Similarly, the receiving substrate holder 62 has a second opening 62f on the sensor central axis Lx that allows ultrasonic waves to pass through, and the second protective member 73 is provided on the surface of the receiving substrate holder 62 so as to cover the second opening 62f. This provides the following effects. If foreign matter remains attached to the first protective member 70 or the second protective member 73, the strength of the ultrasonic waves received by the receiving sensor chip 56 will decrease, which may result in erroneous detection. In this case, it is necessary to replace the first protective member 70 or the second protective member 73 or to perform maintenance such as cleaning. In this embodiment, the first protective member 70 is provided on the surface of the transmission board holder 60 so as to cover the first opening 60f, which makes it easy to replace and maintain the first protective member 70. Similarly, the second protective member 73 is provided on the surface of the receiving board holder 62 so as to cover the second opening 62f, which makes it easy to replace and maintain the second protective member 73.

[0113] As explained with reference to FIG. 22, the transmitting sensor chip 53 and the receiving sensor chip 56 are inclined at an angle α1 as a first angle with respect to the surface of the document P passing between the transmitting sensor chip 53 and the receiving sensor chip 56. The first protective member 70 and the second protective member 73 are inclined at an angle α2, which is a second angle, with respect to the surface of the document P passing between the transmitting sensor chip 53 and the receiving sensor chip 56. The angle α1 and the angle α2 are different, and the angle α2 is gentler than the angle α1. This provides the following effects.

[0114] If the first protective member 70 and the second protective member 73 are parallel to the surface of the document P passing between the transmitting sensor chip 53 and the receiving sensor chip 56, paper dust and other particles are likely to adhere to the first protective member 70 and the second protective member 73. However, since the first protective member 70 and the second protective member 73 are inclined at an angle α2 with respect to the surface of the document P passing between the transmitting sensor chip 53 and the receiving sensor chip 56, the adhesion of foreign matter such as paper dust to the first protective member 70 and the second protective member 73 can be suppressed.

[0115] Furthermore, since the transmitting sensor chip 53 and the receiving sensor chip 56 are inclined at an angle α1 with respect to the surface of the document P passing between the transmitting sensor chip 53 and the receiving sensor chip 56, multiple reflections of ultrasonic waves between the transmitting sensor chip 53 and the document P or between the receiving sensor chip 56 and the document P can be suppressed. Furthermore, since the angles α1 and α2 are different, multiple reflections of ultrasonic waves between the transmitting sensor chip 53 and the first protective member 70 can be suppressed, and multiple reflections of ultrasonic waves between the receiving sensor chip 56 and the second protective member 73 can also be suppressed.

[0116] 5 to 7, the scanner 1 is provided with a transmission-side path forming member 36, which is a member that forms the reading transport path R2, which is a document transport path between the first roller pair 13 and the second roller pair 16, and which fixes the transmission board holder 60. The transmission-side path forming member 36 is provided with a removable cover 37, and when the cover 37 is attached, the transmission board holder 60 is covered by the cover 37. When the cover 37 is removed, the separation roller 15 becomes replaceable and the transmission board holder 60 is exposed. In particular, the first protection member 70 is exposed. This allows easy access to the transmission board holder 60. As a result, for example, replacement and maintenance of the first protection member 70 becomes easy.

[0117] The transmitter board holder 60 also has a fixing portion 60a that fixes the first protective member 70, the transmitter board 52 is fixed to the back side of the fixing portion 60a, and the fixing portion 60a has a first wall portion 60b that is a wall portion facing the side of the fixed transmitter board 52 and covers at least a part of the transmitter board 52. As a result, if a foreign object tries to get around to the transmitter board 52 from the side of the fixing portion 60a, it can be blocked by the first wall portion 60b.

[0118] <Relationship between the configuration of the ultrasonic detection unit and other components of the scanner> Next, the relative positional relationship between the configuration of the ultrasonic detection unit 50 and other components of the scanner 1 will be described. First, the positional relationship between the ultrasonic detection unit 50 and the first roller pair 13 will be described with reference to Fig. 23. Fig. 23 shows the positional relationship between the ultrasonic detection unit 50 and the first roller pair 13 as viewed from upstream in the conveying direction Fp. In Fig. 23, the feed roller 14 and separation roller 15 that make up the first roller pair 13 are indicated by two-dot chain lines. As shown in the figure, at least a part of the transmitting sensor chip 53 and at least a part of the receiving sensor chip 56 are inside the range Ua1 of the first roller pair 13 in the normal direction Da to the document surface S at the nip position of the first roller pair 13. This makes it possible to reduce the device dimensions in the normal direction Da.

[0119] In this embodiment, the entire transmitting sensor chip 53 and the entire receiving sensor chip 56 are located inside the range Ua1 in the normal direction Da, but a part of the transmitting sensor chip 53 and a part of the receiving sensor chip 56 may be located inside the range Ua1 in the normal direction Da. Alternatively, a part of the transmitting sensor chip 53 and the entire receiving sensor chip 56 may be located inside the range Ua1 in the normal direction Da. Alternatively, the entire transmitting sensor chip 53 and a part of the receiving sensor chip 56 may be located inside the range Ua1 in the normal direction Da.

[0120] In this embodiment, at least a part of the receiving substrate 55 and at least a part of the shield member 91 are located inside the range Ua1 of the first roller pair 13 in the normal direction Da to the document surface S at the nip position of the first roller pair 13. This makes it possible to reduce the dimensions of the device in the normal direction Da. In this embodiment, the entire receiving board 55 and the entire shielding member 91 are located inside the range Ua1 in the normal direction Da, but only a portion of the receiving board 55 or a portion of the shielding member 91 may be located inside the range Ua1 in the normal direction Da.

[0121] Note that reference symbol 14a denotes the rotation axis of the feed roller 14, and reference symbol 15a denotes the rotation axis of the separation roller 15. In this embodiment, the distance between the axial centers of the rotation axes 14a and 15a, i.e., the inter-axial distance dk1, is 16.6 mm, which is shorter than the distance between the transmitting sensor chip 53 and the receiving sensor chip 56, i.e., the inter-sensor distance of 24.9 mm. This makes it possible to reduce the area occupied by the first roller pair 13 in the direction along the inter-axial distance dk1, thereby enabling the device dimensions to be reduced. In this embodiment, the shaft diameter of the rotating shaft 14a is 6.0 mm, and the shaft diameter of the rotating shaft 15a is 3.0 to 6.0 mm, for example 3.9 mm or 5.18 mm, both of which are larger than the thickness of the transmitting sensor chip 53 or the receiving sensor chip 56, 0.578 mm.

[0122] Next, the positional relationship between the ultrasonic detection unit 50, the second roller pair 16, and the third roller pair 20 will be described with reference to Fig. 24. Fig. 24 shows the positional relationship between the ultrasonic detection unit 50, the second roller pair 16, and the third roller pair 20 as viewed from upstream in the conveying direction Fp. 24, the second lower roller 17 and the second upper roller 18 that make up the second roller pair 16 are indicated by two-dot chain lines. Note that the contour of the third lower roller 21 that makes up the third roller pair 20 overlaps with the second lower roller 17, and the contour of the third upper roller 22 that makes up the third roller pair 20 overlaps with the second upper roller 18. As will be described in more detail later, the second upper roller 18 and the third upper roller 22 are both arranged to move forward and backward relative to the opposing rollers, and Figure 24 shows the state in which the second upper roller 18 and the third upper roller 22 are both in contact with the opposing rollers.

[0123] As shown in the figure, at least a part of the transmitting sensor chip 53 and at least a part of the receiving sensor chip 56 are inside the range Ua2 of the second roller pair 16 or the third roller pair 20 in the normal direction Da to the document surface S at the nip position of the second roller pair 16 or the third roller pair 20. This makes it possible to reduce the device dimensions in the normal direction Da to the document surface S at the nip position of the second roller pair 16 or the third roller pair 20.

[0124] In this embodiment, the entire transmitting sensor chip 53 and the entire receiving sensor chip 56 are located inside the range Ua2 in the normal direction Da, but a portion of the transmitting sensor chip 53 and a portion of the receiving sensor chip 56 may be located inside the range Ua2 in the normal direction Da. Alternatively, a portion of the transmitting sensor chip 53 and the entire receiving sensor chip 56 may be located inside the range Ua2 in the normal direction Da. Alternatively, the entire transmitting sensor chip 53 and a portion of the receiving sensor chip 56 may be located inside the range Ua2 in the normal direction Da. The relationship between the dimensions of the rotation axes of the second lower roller 17, the second upper roller 18, the third lower roller 21, and the third upper roller 22 and the dimensions of the transmitting sensor chip 53 and the receiving sensor chip 56 will be explained later.

[0125] In this embodiment, a portion of the transmitting board 52 and the entire receiving board 55 are inside the range Ua1 in the normal direction Da. However, the entire transmitting board 52 and the entire receiving board 55 may be inside the range Ua1 in the normal direction Da. Alternatively, a portion of the transmitting board 52 and a portion of the receiving board 55 may be inside the range Ua1 in the normal direction Da. Alternatively, the entire transmitting board 52 and a portion of the receiving board 55 may be inside the range Ua1 in the normal direction Da.

[0126] Furthermore, the distance between the center of the rotation axis of the second lower roller 17 and the center of the rotation axis of the second upper roller 18, or the distance between the center of the rotation axis of the third lower roller 21 and the center of the rotation axis of the third upper roller 22, i.e., the inter-axis distance dk2, is 15.4 mm, which is shorter than the distance between the transmitting sensor chip 53 and the receiving sensor chip 56, i.e., the inter-sensor distance of 24.9 mm. This makes it possible to reduce the area occupied by the second roller pair 16 or the third roller pair 20 in the direction along the inter-axis distance dk2, thereby making it possible to reduce the dimensions of the device.

[0127] Next, the transmitting substrate 52 and the receiving substrate 55 are inclined with respect to the normal direction Da to the document surface S that passes between the transmitting sensor chip 53 and the receiving sensor chip 56, and the transmitting surface 53a of the transmitting sensor chip 53 is along the surface of the transmitting substrate 52, and the receiving surface 56a of the receiving sensor chip 56 is along the surface of the receiving substrate 55. At least a part of the transmitting substrate 52 and at least a part of the receiving substrate 55 are within the range of the second roller pair 16 or the third roller pair 20 in the normal direction Da to the document surface S at the nip position of the second roller pair 16 or the third roller pair 20. This makes it possible to reduce the device dimensions in the normal direction Da.

[0128] In this embodiment, the entire transmitting board 52 and a portion of the receiving board 55 are inside the range Ua2 in the normal direction Da, but a portion of the transmitting board 52 and a portion of the receiving board 55 may also be inside the range Ua2 in the normal direction Da. Alternatively, a portion of the transmitting board 52 and the entire receiving board 55 may also be inside the range Ua2 in the normal direction Da. Alternatively, the entire transmitting board 52 and the entire receiving board 55 may also be inside the range Ua2 in the normal direction Da.

[0129] Furthermore, in this embodiment, the entire transmitting sensor chip 53 and the entire receiving sensor chip 56 are located inside the range Ua2 in the normal direction Da. However, a portion of the transmitting sensor chip 53 and a portion of the receiving sensor chip 56 may be located inside the range Ua2 in the normal direction Da. Alternatively, a portion of the transmitting sensor chip 53 and the entire receiving sensor chip 56 may be located inside the range Ua2 in the normal direction Da. Alternatively, the entire transmitting sensor chip 53 and a portion of the receiving sensor chip 56 may be located inside the range Ua2 in the normal direction Da.

[0130] In this embodiment, a part of the receiving substrate 55 and a part of the shielding member 91 are inside the range Ua2 in the normal direction Da, which makes it possible to reduce the dimensions of the device in the normal direction Da. In this embodiment, a portion of the receiving board 55 and a portion of the shielding member 91 are located inside the range Ua1 in the normal direction Da, but the entire receiving board 55 or the entire shielding member 91 may be located inside the range Ua1 in the normal direction Da.

[0131] Next, the configuration of the second roller pair 16 will be further described with reference to FIG. In this embodiment, two pairs of second rollers 16 are provided along the X-axis direction, i.e., the document width direction, and the two pairs of second rollers 16 are provided at positions symmetrical to each other in the document width direction, sandwiching the center position CL of the document P. Reference numeral 17a denotes a rotation shaft of the second lower roller 17. Symbol 18a1 is a rotating shaft located between the two second upper rollers 18, and symbol 18a2 is a rotating shaft located on both sides of the two second upper rollers 18, and the shaft diameter of rotating shaft 18a1 is smaller than the shaft diameter of rotating shaft 18a2. Rotation shaft 18a2 located in the +X direction is connected to first universal joint 31A. Second universal joint 31B is further provided in the +X direction relative to first universal joint 31A, and first universal joint 31A and second universal joint 31B are connected by rotation shaft 18a3.

[0132] The second upper roller 18 moves forward and backward relative to the second lower roller 17 and power is transmitted to it, so the second upper roller 18 can be driven while moving forward and backward relative to the second lower roller 17 by the first universal joint 31A and the second universal joint 31B. 25 shows a state in which the second upper roller 18 is in contact with the second lower roller 17, and the upper view in Fig. 25 shows a state in which the second upper roller 18 is farthest from the second lower roller 17. The symbol M1 indicates the range in which the second upper roller 18 moves.

[0133] As shown in the figure, in this embodiment, the entire receiving sensor chip 56 and the entire receiving substrate 55 are inside the range M1 in the normal direction Da, so the device dimensions in the normal direction Da can be reduced. In this embodiment, the entire receiving sensor chip 56 and the entire receiving substrate 55 are located inside the range M1 in the normal direction Da, but only a portion of the receiving sensor chip 56 and a portion of the receiving substrate 55 may be located inside the range M1 in the normal direction Da. Alternatively, only the entire receiving sensor chip 56 and a portion of the receiving substrate 55 may be located inside the range M1 in the normal direction Da. The relationship between the third roller pair 20, the receiving sensor chip 56, and the receiving board 55 is the same as the relationship between the second roller pair 16, the receiving sensor chip 56, and the receiving board 55 described above.

[0134] In this embodiment, the diameter of the rotating shaft 17a is 6.0 mm. The diameter of the rotating shaft 18a1 is 4.0 mm, the diameter of the rotating shaft 18a2 is 5.0 mm, and the diameter of the rotating shaft 18a3 is 4.5 mm, all of which are larger than the thickness of the transmitting sensor chip 53 or the receiving sensor chip 56.

[0135] As described above, the path length between the first roller pair 13 and the second roller pair 16, i.e., the path length of the downstream feeding path R1, is shorter than the path length between the second roller pair 16 and the third roller pair 20, i.e., the path length of the reading conveying path R2. This makes it possible to reduce the path length between the first roller pair 13 and the second roller pair 16, and therefore the dimensions of the device.

[0136] 13 to 15, the transmitting board 52 and the receiving board 55 have long sides E2 and short sides E1, and are arranged so that the short sides E1 are aligned along the conveyance direction Fp. This allows the first roller pair 13 and the second roller pair 16 to be closer to each other in the conveyance direction Fp, which contributes to the miniaturization of the device.

[0137] The length of the short side E1 of the transmitting board 52 and the receiving board 55 is shorter than the length of the glass plate 32e in the conveyance direction Fp. The configurations of the first reading unit 32 and the second reading unit 33 will now be described with reference to Fig. 26. The configurations of the first reading unit 32 and the second reading unit 33 are basically the same, and the configuration of the first reading unit 32 will be described below.

[0138] The first reading unit 32 includes a lower housing 32f and an upper housing 32g, and a sensor substrate 32a is provided on the lower housing 32f. A linear image sensor 32b, which is an example of a reading sensor, is provided on the sensor substrate 32a, and the image sensor 32b receives reflected light arriving from the original P via a lens 32c. Reference numeral 32d denotes a light source that illuminates the original P. A glass plate 32e is provided in the upper housing 32g. The glass plate 32e transmits light reflected by the document P to the lens 32c, and also has the function of coming into contact with the document P and guiding the document P downstream.

[0139] As described above, the length of the short sides E1 of the transmitting board 52 and the receiving board 55 is shorter than the length of the glass plate 32e in the conveyance direction Fp. In this embodiment, the length of the short sides E1 of the transmitting board 52 and the receiving board 55 is 8.6 mm, the length of the long sides E2 is 26.8 mm, and the length of the glass plate 32e in the conveyance direction Fp is 12.6 mm. As a result, the length of the short side E1 of the transmitting substrate 52 and the receiving substrate 55 in the conveyance direction Fp can be reduced. As a result, the first roller pair 13 and the second roller pair 16 can be brought even closer to each other in the conveyance direction Fp, which contributes to further miniaturization of the device.

[0140] In this embodiment, the thickness of the glass plate 32e is 1.1 mm, which is larger than the thickness of the transmitting sensor chip 53 or the receiving sensor chip 56, which is 0.578 mm.

[0141] Next, Figure 27 shows the positional relationship between the transmitting substrate 52 and the transmitting sensor chip 53, and the sensor substrate 32a and image sensor 32b when viewed from upstream in the transport direction Fp. In Figure 27, the sensor substrate 32a and image sensor 32b are indicated by two-dot chain lines. As shown in the figure, the transmitting sensor chip 53 is located on the +Da side of the image sensor 32b in the normal direction Da, i.e., on the side of the second reading unit 33. This makes it possible to reduce the amount by which the transmitting sensor chip 53 protrudes from the first reading unit 32 to the -Da side, i.e., downward, in the normal direction Da, and thus makes it possible to reduce the device dimensions in the normal direction Da.

[0142] Next, Fig. 28 shows the positional relationship between the transmitting substrate 52 and the transmitting sensor chip 53 when viewed from upstream in the transport direction Fp, and the second reading unit 33. In Fig. 28, the outline of the second reading unit 33 and the image sensor 32B provided in the second reading unit 33 are indicated by two-dot chain lines. The second reading unit 33 moves forward and backward relative to the first reading unit 32, with the bottom diagram in Fig. 28 showing the state where it is furthest away from the first reading unit 32 and the top diagram in Fig. 28 showing the state where it is furthest advanced relative to the first reading unit 32. The range indicated by the symbol M2 indicates the region where the second reading unit 33 moves. As shown in the figure, at least a part of the receiving sensor chip 56 is inside the range M2 in the normal direction Da. This makes it possible to reduce the dimensions of the device in the normal direction Da. Similarly, at least a portion of the receiving substrate 55 is located inside the range M2 in the normal direction Da. This makes it possible to reduce the dimensions of the device in the normal direction Da.

[0143] In this embodiment, the entire receiving sensor chip 56 and the entire receiving substrate 55 are located inside the range M2 in the normal direction Da, but only a portion of the receiving sensor chip 56 and a portion of the receiving substrate 55 may be located inside the range M2 in the normal direction Da. Alternatively, only the entire receiving sensor chip 56 and a portion of the receiving substrate 55 may be located inside the range M2 in the normal direction Da.

[0144] Next, Figure 29 shows the areas occupied by the first roller pair 13, the second roller pair 16, the transport motor 47, the transmitting sensor chip 53, the transmitting board 52, the receiving sensor chip 56, and the receiving board 55 when viewed from the X-axis direction. As shown in the figure, at least a part of the transmitting substrate 52 and at least a part of the transmitting sensor chip 53 are located within the area occupied by the transport motor 47. This makes it possible to prevent the device from becoming too large. In this embodiment, a portion of the transmitting substrate 52 and the entire transmitting sensor chip 53 are located within the area occupied by the transport motor 47, but the entire transmitting substrate 52 and the entire transmitting sensor chip 53 may be located within the area occupied by the transport motor 47, or alternatively, the entire transmitting substrate 52 and the entire transmitting sensor chip 53 may be located within the area occupied by the transport motor 47.

[0145] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these modifications are also included in the scope of the present invention. For example, in the above embodiment, the medium conveying device 100 is applied to a scanner 1, which is an example of an image reading device, but this is not limited to this, and the medium conveying device 100 may also be applied to a recording device that records on a medium, or a post-processing device that performs post-processing on a medium, such as stapling or punching. [Explanation of symbols]

[0146] 1...scanner, 2...device main body, 3...first unit, 4...second unit, 4a...top surface, 5...third unit, 6...main body support section, 6a...standing wall section, 6b...elastic deformation section, 6c...main body rotation axis, 6e...first contact section, 6f...second contact section, 7...operation section, 7a, 7b, 7c...operation buttons, 7d...display section, 8a...unlock section, 9...document support, 10...upper opening / closing section, 11...document support section, 13...first roller pair, 14...feed roller, 15...separation roller, 15a...rotation axis, 15b...torque limiter, 16...second roller pair, 17...second lower roller, 18...second upper roller, 2 0...third roller pair, 21...third lower roller, 21a...rotating shaft, 22...third upper roller, 22a...rotating shaft, 24...fourth roller pair, 25...fourth drive roller, 26...fourth driven roller, 28...fifth roller pair, 29...fifth drive roller, 30...fifth driven roller, 31A...first universal joint, 31B...second universal joint, 32...first reading unit, 32a...sensor board, 32b...image sensor, 32c...lens, 32d...light source, 32e...glass plate, 32f...lower housing, 32g...upper housing, 33...second reading unit, 34...pressure spring, 35...flap, 36... Transmitting side path forming member, 37...cover, 37a...opening, 38...roller holding member, 39...receiving side path forming member, 39a...opening, 39b...positioning portion, 47...conveying motor, 48...main board, 50...ultrasonic detection portion, 51...voltage application portion, 50A...transmitting unit, 50B...receiving unit, 52...transmitting board, 52a...opening, 52b...recess, 52c...connector, 52d...board surface, 53...transmitting sensor chip, 53a...transmitting surface, 54...transmitting board fixing screw, 55...receiving board, 55c...connector, 55d...first board surface, 55e...second board surface, 56...receiving sensor chip, 56a...receiving surface, 57...receiving board fixing screw, 58...transmitting circuit, 59...receiving circuit, 60...transmitting board holder, 60a...fixing portion, 60b...first wall portion, 60c...protective member positioning portion, 60d...board positioning portion, 60e...screw hole, 60f...first opening, 60g...screw hole, 60h...second wall portion, 60j...screw fixing portion, 60k...screw fixing portion, 60m...protrusion, 61...transmitting side holder fixing screw, 62...receiving board holder, 62a...fixing portion, 62c...protective member positioning portion, 62d...board positioning portion, 62e...hole portion, 62f...second opening, 62j...fixed portion, 62k...positioned portion,63...receiving side holder fixing screw, 65...first enclosing member, 65a...opening, 67...second enclosing member, 70...first protective member, 70a...wire rod, 70b...opening, 71...first holding member, 71a...recess, 71b...opening, 73...second protective member, 74...second holding member, 76...transmitting side cable, 77...receiving side cable, 80...control unit, 81...calculating unit, 82...conveyance control unit, 83...reading control unit, 84...multiple feed determination unit, 85...storage unit, 86...interface section, 87...external device, 91...shield member, 100...medium conveying device, 210...element substrate, 211...substrate main body, 211A...opening, 211B...partition wall, 212...vibration plate, 212A...vibration section, 213...base substrate, 220...piezoelectric element, 221...first electrode, 222...piezoelectric film, 223...second electrode, Tr...ultrasonic transducer, R0...upstream feeding path, R1...downstream feeding path, R2...reading conveying path, R3...U-turn discharge path,

Claims

1. a first roller pair that transports the medium in a transport direction; a second roller pair disposed downstream of the first roller pair in the conveying direction; an ultrasonic detection unit disposed between the first roller pair and the second roller pair in the conveying direction; A medium transport device comprising: The ultrasonic detection unit a transmitting sensor tip that emits ultrasonic waves along a first axis toward a first surface of the transported medium; a receiving sensor chip that is disposed on the first axis at a position where the medium is sandwiched between the transmitting sensor chip and the receiving sensor chip, and that receives ultrasonic waves; a transmitting substrate on which the transmitting sensor chip is provided, the transmitting substrate having the transmitting sensor chip mounted on a substrate surface; a receiving substrate on which the receiving sensor chip is provided, the receiving substrate having the receiving sensor chip mounted on a substrate surface; an amplifier provided on the receiving substrate for amplifying a reception signal of the ultrasonic wave received by the receiving sensor chip; a shielding member provided on the receiving board and covering at least a portion of the amplifier; and a height of the receiving sensor chip relative to the receiving substrate is lower than a height of the shielding member relative to the receiving substrate; A medium transport device characterized by:

2. 2. The medium transport device according to claim 1, the first axis is inclined with respect to a plane of the medium passing between the transmitting sensor chip and the receiving sensor chip; The thickness of the transmitting sensor chip is smaller than the thickness of the transmitting substrate; The thickness of the receiving sensor chip is thinner than the thickness of the receiving substrate, at least a portion of the transmitting sensor chip and at least a portion of the receiving sensor chip are within the range of the second roller pair in a direction normal to a surface of the medium at a nip position of the second roller pair; A medium transport device characterized by:

3. 2. The medium transport device according to claim 1, In the receiving substrate, the amplifier and the shielding member are provided on a surface opposite to a surface on which the receiving sensor chip is provided. A medium transport device characterized by:

4. 2. The medium transport device according to claim 1, a connector is provided on the receiving substrate on a surface opposite to a surface facing the receiving sensor chip; the amplifier and the shielding member are disposed on the surface of the receiving board on which the connector is provided; A medium transport device characterized by:

5. 2. The medium transport device according to claim 1, In the receiving substrate, the amplifier is disposed on a surface on which the receiving sensor chip is provided, the shielding member covers the receiving sensor chip in addition to the amplifier; A medium transport device characterized by:

6. 2. The medium transport device according to claim 1, At least a part of the receiving substrate and at least a part of the shielding member are within the first roller pair in a direction normal to the surface of the medium at the nip position of the first roller pair; or within the range of the second roller pair in a direction normal to the surface of the medium at the nip position of the second roller pair; A medium transport device characterized by:

7. 2. The medium transport device according to claim 1, the first axis is inclined with respect to a plane of the medium passing between the transmitting sensor chip and the receiving sensor chip; When calibrating the ultrasonic detection unit, the ultrasonic wave is received by the receiving sensor chip in a state where a bias voltage is applied to the receiving sensor chip, and the received signal is amplified by the amplifier. A medium transport device characterized by:

8. 8. The medium transport device according to claim 7, the first axis is inclined with respect to a plane of the medium passing between the transmitting sensor chip and the receiving sensor chip; When detecting a double feed of media by the ultrasonic detection unit, the ultrasonic wave is received by the receiving sensor chip in a state where a bias voltage is applied to the receiving sensor chip, and the received signal is amplified by the amplifier. A medium transport device characterized by:

9. The medium transport device according to any one of claims 1 to 8; a reading unit positioned downstream of the second roller pair in the transport direction and configured to read an image on the medium; An image reading device comprising:

Images