Ultrasonic apparatus, detection apparatus, and printing apparatus

An ultrasonic apparatus includes a first ultrasonic sensor that transmits an ultrasonic wave to an object and receives the ultrasonic wave reflected by the object, a second ultrasonic sensor that transmits an ultrasonic wave to the object and receives the ultrasonic wave reflected by the object, an determination circuit that outputs an error signal when the difference between a first distance between the first ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the first ultrasonic sensor and a second distance between the second ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the second ultrasonic sensor is equal to or greater than a threshold value.

The present application is based on, and claims priority from JP Application Serial Number 2019-216439, filed Nov. 29, 2019, the disclosure of which is hereby incorporated by reference herein in its all.

BACKGROUND

1. Technical Field

The present disclosure relates to an ultrasonic apparatus, a detection apparatus, and a printing apparatus.

2. Related Art

In the related art, there is known a detection apparatus that detects an abnormality such as wrinkles in a sheet by using ultrasonic waves (see, for example, JP-A-2002-211797). The detection apparatus described in JP-A-2002-211797 transmits ultrasonic waves to a sheet from an ultrasonic transmission apparatus, and receives the ultrasonic waves that passed through the sheet by an ultrasonic reception apparatus. In this detection apparatus, the drive signal input to the ultrasonic transmission apparatus is compared with the reception signal output from the ultrasonic reception apparatus, and the change in the inclination angle of the sheet caused by the wrinkles of the sheet is detected by using a phase shift.

However, the position of the wrinkles occurring on the sheet, the shape of the wrinkles, the size of the wrinkles, and the like vary depending on the material of the sheet, the method of transporting the sheet, the ambient environment such as humidity, and the position of the wrinkles that occur has various patterns. For example, in a transport apparatus that transports a sheet, there are wrinkles and the like that occur only in the upstream of the conveyance and less likely occur in the downstream. In the wrinkle detection apparatus of JP-A-2002-211797 described above, since only one pair of an ultrasonic transmission apparatus and an ultrasonic reception apparatus are provided, for example, it is difficult to detect wrinkles that occur in the upstream of the sheet and are less likely to occur in the downstream of the sheet. Further, when the wrinkles are formed over a wide range, the inclination of the sheet becomes gentle, and it is difficult to detect the wrinkles by using the phase shift from the comparison between the drive signal and the received signal. The above is described with respect to the wrinkles of the sheet, but the same applies the case where an object other than a sheet is used as an object and abnormalities such as unevenness and the like on the object are detected, and even if ultrasonic waves are transmitted/received to/from only one predetermined location of the object, the abnormality of the object may not be detected in some cases.

SUMMARY

An ultrasonic apparatus according to a first aspect includes a first ultrasonic sensor that transmits a ultrasonic wave to an object and receives the ultrasonic wave reflected by the object, a second ultrasonic sensor that transmits an ultrasonic wave to the object and receives the ultrasonic wave reflected by the object, an error output portion that outputs an error signal when the difference between a first distance between the first ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the first ultrasonic sensor and a second distance between the second ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the second ultrasonic sensor is equal to or greater than a threshold value.

A detection apparatus according to a second aspect includes the ultrasonic apparatus according to the first aspect, and a detector that detects an abnormality of the object based on the error signal output from the ultrasonic apparatus.

A printing apparatus according to a third aspect includes a detection apparatus according to the second aspect and a printer that forms an image on the object, and controls printing by the printer based on a detection result of the abnormality by the detector.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First Embodiment

A first embodiment will be described below.

Schematic Configuration of Printing Apparatus100

FIG.1is a schematic view showing a schematic configuration of a printing apparatus100according to a first embodiment.FIG.2is a block view showing a functional configuration of the printing apparatus100. The printing apparatus100according to the present embodiment is an apparatus that prints an image on a large-sized sheet1(object) such as a sign display. As shown inFIGS.1and2, the printing apparatus100includes a supplier110, a transporter120, a heater130, a carriage140, a movement mechanism150, and a controller160(seeFIG.2).

The supplier110is a section for supplying the sheet1. In the example shown inFIG.1, the supplier110is configured to supply the sheet1wound around a core material1A to the inside of the apparatus. The supplier110includes, for example, a core material holder111that holds the core material1A, and supplies the sheet1to the inside of the apparatus by rotating the core material holder111. The configuration of the supplier110is not limited to the configuration shown inFIG.1. For example, the sheets1placed on a tray or the like may be supplied to the inside of the apparatus one by one. In addition, the type of the sheet1supplied from the supplier110is not particularly limited, and various types of media such as a paper surface, a film, and a woven fabric can be used.

The transporter120constitutes a transport mechanism and transports the sheet1supplied from the supplier110along a transport path10. In the example shown inFIG.1, the transporter120transports the sheet1toward the downstream of the transport path10by winding the leading end of the sheet1supplied from the supplier110. In such a configuration, it is possible to reversely transport the sheet1from the downstream to the upstream by reversing the winding direction of the transporter120and the supply direction of the supplier110. The configuration of the transporter120is not limited to the configuration shown inFIG.1. For example, the sheet1may be transported by rotating a plurality of transport rollers.

A platen11is provided at a portion of the transport path facing the carriage140. The platen11corresponds to the disposition portion of the present disclosure, and in the present embodiment, ink is ejected from a printer141(seeFIG.2) a on the carriage140onto the sheet1transported on the platen11. In addition, the transport direction (first direction) of the sheet1at a position facing the platen11in the transport path along which the sheet1is transported is defined as a Y direction.

The heater130includes a first heater131, a second heater132, and a third heater133. The first heater131is disposed in the downstream of the platen11in the transport path10and heats the surface of the sheet1. The second heater132is provided on the platen11and heats the back surface of the sheet1. The first heater131and the second heater132are heaters for drying the ink ejected on the sheet1. As shown inFIG.1, the third heater133is disposed in the upstream of the platen11in the transport path10and heats the sheet1before being transported to the platen11, thereby drying the sheet1to suppress the occurrence of wrinkles.

FIG.3is a schematic view showing a schematic configuration in the vicinity of the platen11of the printing apparatus100. As shown inFIG.3, the carriage140is provided at a position facing the platen11. Further, the printing apparatus100is provided with a shaft102extending in an X direction orthogonal to the transport direction (Y direction) of the sheet1at a position facing the platen11, and both ends of the shaft102are fixed to a frame101of the printing apparatus100. Part of the carriage140is slidably engaged with the shaft102, which allows the carriage140to move in the X direction. The printer141is mounted on the carriage140, and an ultrasonic apparatus200is attached on the side surface of the carriage140. The specific configurations of the printer141mounted on the carriage140and the ultrasonic apparatus200attached on the carriage140will be described later.

The movement mechanism150is an apparatus for moving the carriage140in the X direction based on a command from the controller160. Although illustration of a specific configuration of the movement mechanism150is omitted, for example, a configuration including a timing belt disposed parallel to the shaft102and a drive motor for driving the timing belt can be exemplified. In such a configuration, it is possible to move the carriage140to a +X side by rotating the drive motor in the normal direction and to move the carriage140to a −X side by reversing the drive motor. The configuration of the movement mechanism150is not limited to the above, and may be any configuration as long as the movement mechanism150allows the carriage140to reciprocate in the X direction.

Next, the printer141mounted on the carriage140and the ultrasonic apparatus200attached on the carriage140will be described. As shown inFIG.3, the carriage140of the present embodiment includes the printer141. The ultrasonic apparatus200is fixed to the side surface of the carriage140on the +X side.

Configuration of Printer141

The printer141has nozzles that individually eject ink in a portion facing the sheet1transported to the platen11. A plurality of nozzles are provided corresponding to inks of a plurality of colors. For example, a piezo element is disposed in these nozzles, and by driving the piezo element, the ink droplets supplied from the ink tank are ejected from the nozzle.

Configuration of Ultrasonic Apparatus200

FIG.4is a cross-sectional view of the ultrasonic apparatus200taken along the line IV-IV ofFIG.3, andFIG.5is a cross-sectional view of the ultrasonic apparatus200taken along the line V-V ofFIG.3. As shown inFIGS.3and4, the ultrasonic apparatus200includes a first ultrasonic sensor210, a second ultrasonic sensor220, a first pedestal portion231, a second pedestal portion232, and a circuit board240, a first protective member251, a second protective member252, a first holder261, a second holder262, and a shield member300.

Configuration of Shield Member300

The shield member300is a box-shaped member in which the first ultrasonic sensor210, the second ultrasonic sensor220, the first pedestal portion231, the second pedestal portion232, the circuit board240, the first protective member251, the second protective member252, the first holder.261, and the second holder262are provided. The outer shape of the shield member may be a rectangular parallelepiped, a cylindrical shape, or any other shape. In the present embodiment, an example in which the shield member300is formed in a rectangular parallelepiped shape is shown.

Specifically, the shield member300is made of a conductive material such as metal, and is formed in a container box shape having an opening on the side facing the platen11. That is, the shield member300includes a rectangular top surface portion310disposed on a −Z side, a first side surface portion321, a second side surface portion322, a third side surface portion323, and a fourth side surface portion324rising from the edge of the top surface portion310, and a rectangular bottom surface portion330disposed on a +Z side. The first side surface portion321and the second side surface portion322are side surfaces parallel to a ZY plane, and among the side surface portions, the first side surface portion321is fixed in contact with the +X side surface of the carriage140. The third side surface portion323and the fourth side surface portion324are side surfaces parallel to a ZX plane, the third side surface portion323is disposed on the +Y side, and the fourth side surface portion324is disposed on the −Y side. Further, the bottom surface portion330is provided with a first opening window331and a second opening window332provided in the Y direction. The first opening window331and the second opening window332are through holes that communicate with the inside and the outside of the shield member300. Such a shield member300may be configured by combining a plurality of parts. For example, the shield main body portion including the top surface portion310, the first side surface portion321, the second side surface portion322, the third side surface portion323, and the fourth side surface portion324, and the bottom surface portion330may be detachably provided in the shield main body portion. Further, the shield main body portion may be formed by combining a first body including the first side surface portion321and a second body including the second side surface portion322.

In the shield member300of the present embodiment, as shown inFIGS.4and5, the circuit board240is disposed on the side of the first side surface portion321in the internal space of the shield member300, the first ultrasonic sensor210is disposed facing the first opening window331, and the second ultrasonic sensor220is disposed facing the second opening window332. For example, as shown inFIGS.4and5, the first side surface portion321is provided with a first fixing portion301, and the circuit board240is fixed to the first fixing portion301. Further, a second fixing portion302and a third fixing portion303are provided on the first side surface portion321and the second side surface portion322. The first pedestal portion231to which the first ultrasonic sensor210is fixed is fixed to the second fixing portion302, and the second pedestal portion232to which the second ultrasonic sensor220is fixed is fixed to the third fixing portion303. In addition, the top surface portion310is provided with a wiring hole311through which a coupling wire that couples the circuit board240and the controller160is inserted.

Further, the shield member300includes a holder holding portion304between the second fixing portion302and the third fixing portion303, and the bottom surface portion330. The holder holding portion304includes a first engaging portion304A that detachably engages the first holder261between the first ultrasonic sensor210and the first opening window331, and a second engaging portion304B that detachably engages the second holder262between the second ultrasonic sensor220and the second opening window332. Then, the first holder261to which the first protective member251is fixed is held in the first engaging portion304A, and the second holder262to which the second protective member252is fixed is held in the second engaging portion304B. As a result, the first protective member251and the second protective member252are provided inside the shield member300. Hereinafter, each configuration provided inside the shield member300will be described in detail.

Configuration of Ultrasonic Sensors210and220

The first ultrasonic sensor210and the second ultrasonic sensor220are sensors that transmit ultrasonic waves toward the sheet1and receive ultrasonic waves reflected by the sheet1.FIG.6is a cross-sectional view showing a schematic configuration of the first ultrasonic sensor210. Since the first ultrasonic sensor210and the second ultrasonic sensor220have the same configuration, the configuration of the first ultrasonic sensor210will be described here, and the configuration of the second ultrasonic sensor220will be omitted.

As shown inFIG.6, the first ultrasonic sensor210includes an element substrate41and a piezoelectric element42. The element substrate41includes a substrate body portion411and a vibrating plate412provided on one surface side of the substrate body portion411. Here, in the following description, the substrate thickness direction of the element substrate41is a Z direction. The Z direction is a transmission and reception direction in which ultrasonic waves are transmitted from the first ultrasonic sensor210, and is a direction intersecting the X direction and the Y direction. The substrate body portion411is a substrate that supports the vibrating plate412, and is made of a semiconductor substrate such as Si. The substrate body portion411is provided with an opening portion411A that penetrates the substrate body portion411along the Z direction.

The vibrating plate412is made of SiO2, a stacked body of SiO2and ZrO2, or the like, and is provided on the −Z side of the substrate body portion411. The vibrating plate412is supported by a partition wall411B of the substrate body portion411that constitutes the opening411A, and closes the −Z side of the opening411A. A portion of the vibrating plate412that overlaps the opening portion411A when viewed from the Z direction constitutes a vibrating portion412A.

The piezoelectric element42is provided on the vibrating plate412and at a position overlapping each vibrating portion412A when viewed from the Z direction. As shown inFIG.6, the piezoelectric element42is configured by sequentially stacking a first electrode421, a piezoelectric film422, and a second electrode423on the vibrating plate412.

Here, one vibrating portion412A and the piezoelectric element42provided on the vibrating portion412A constitute one ultrasonic transducer Tr. Although illustration is omitted, in the present embodiment, the first ultrasonic sensor210is configured by arranging such ultrasonic transducers Tr in a two-dimensional array structure.

In the first ultrasonic sensor210, the piezoelectric film422expands and contracts when a pulse wave voltage of a predetermined frequency is applied between the first electrode421and the second electrode423of each ultrasonic transducer Tr. As a result, the vibrating portion412A vibrates at a frequency according to the opening width of the opening portion411A and the like, and ultrasonic waves are transmitted from the vibrating portion412A toward the +Z side. Further, when the ultrasonic waves are input from the opening411A, the vibrating portion412A vibrates, and a potential difference is generated between the first electrode421side and the second electrode423side of the piezoelectric film422. As a result, the first ultrasonic sensor210outputs a reception signal according to the potential difference generated in the piezoelectric film422. In such a configuration, the +Z side surface of the element substrate41serves as an ultrasonic wave transmission and reception surface211of the first ultrasonic sensor210.

As described above, the second ultrasonic sensor220has the same configuration as the first ultrasonic sensor210. That is, the second ultrasonic sensor220is configured to include the element substrate41and the piezoelectric element42, and the +Z side surface of the element substrate41is used as the ultrasonic wave transmission and reception surface221of the second ultrasonic sensor220to perform ultrasonic wave transmission and reception processing.

Configuration of Pedestal Portions231and232

The first pedestal portion231has a flat surface facing the first opening window331, and the first ultrasonic sensor210is fixed to the flat surface. Similarly, the surface of the second pedestal portion232facing the second opening window332is formed into a flat surface, and the second ultrasonic sensor220is fixed to the flat surface. As described above, the first pedestal portion231is fixed to the second fixing portion302of the shield member300, and the second pedestal portion232is fixed to the third fixing portion303of the shield member300. In the present embodiment, an example of fixing the first pedestal portion231and the second pedestal portion232to the second fixing portion302and the third fixing portion303provided on the first side surface portion321and the second side surface portion322of the shield member is shown, but is not limited to thereto. For example, the second fixing portion302and the third fixing portion303may be fixed to the circuit board240fixed to the shield member300.

Configuration of Circuit Board240

The circuit board240is disposed parallel or substantially parallel to the first side surface portion321and the second side surface portion322. More specifically, the circuit board240is disposed such that the projected area of the circuit board240when projected onto a YZ plane is 70% or more of the area of the circuit board240. The area of the circuit board240is the area of one surface orthogonal to the board thickness of the circuit board240. That is, the angle formed between the board surface of the circuit board240and the YZ plane is 0° or more and 45° or less. With such a configuration, for example, the ultrasonic apparatus200can be downsized as compared with the case where the circuit board240is disposed parallel to the top surface portion310and the bottom surface portion330. That is, in the present embodiment, the ultrasonic apparatus200on the +X side of the carriage140is fixed, and the carriage140can be moved in the X direction by the movement mechanism150. In such a configuration, when the circuit board240is disposed parallel to an XY plane, the width of the ultrasonic apparatus200in the X direction increases, and the moving range of the carriage140decreases by the increased dimension, or the printing apparatus100may be increased in size. On the other hand, in the present embodiment, by disposing the circuit board240to be parallel to the YZ plane, it is possible to suppress an increase in the width of the ultrasonic apparatus200in the X direction. Further, the circuit board240is disposed closer to the first side surface portion321than the midpoint between the first side surface portion321and the second side surface portion322. That is, the circuit board240is disposed between the first side surface portion321and the midpoint between the first side surface portion321and the second side surface portion322.

This circuit board240is coupled to the first ultrasonic sensor210and the second ultrasonic sensor220, and includes a first control circuit241, a second control circuit242, and a determination circuit243as shown inFIG.2. The first control circuit241outputs, to the first ultrasonic sensor210, a drive signal for transmitting ultrasonic waves from the first ultrasonic sensor210. In addition, the first control circuit241receives a reception signal output from the first ultrasonic sensor210when the first ultrasonic sensor210receives an ultrasonic wave, and performs signal processing such as amplification processing. Further, the first control circuit241calculates a first distance, which is the distance between the first ultrasonic sensor210and the sheet1, based on the time from the transmission timing of ultrasonic waves to the reception timing of ultrasonic waves in the first ultrasonic sensor210.

The second control circuit242outputs, to the second ultrasonic sensor220, a drive signal for transmitting ultrasonic waves from the second ultrasonic sensor220. In addition, the second control circuit242receives a reception signal output from the second ultrasonic sensor220when the second ultrasonic sensor220receives an ultrasonic wave, and performs signal processing such as amplification processing. Further, the second control circuit242calculates a second distance, which is the distance between the second ultrasonic sensor220and the sheet1, based on the time from the transmission timing of ultrasonic waves to the reception timing of ultrasonic waves in the second ultrasonic sensor220.

The determination circuit243corresponds to an error output portion according to the present disclosure, and determines whether the difference between the first distance calculated by the first control circuit241and the second distance calculated by the second control circuit is within a predetermined threshold value. Then, the determination circuit243outputs an error signal to the controller160when the difference between the first distance and the second distance exceeds the threshold value. That is, when the difference between the first distance and the second distance is large, there is a possibility that an abnormality such as wrinkles has occurred in the sheet1, and therefore an error signal indicating this possibility is output to the controller160.

Configuration of Protective Members251and252and Holders261and262

FIG.7is a view showing a schematic configuration of the first protective member251. Since the second protective member252has the same configuration as the first protective member251, the description thereof will be omitted here. InFIG.7, an Xm direction and a Ym direction are directions intersecting with the Z direction, and the normal line of an XmYm plane is inclined at a predetermined angle θ with respect to the Z direction. In the following description, the normal line of the XmYm plane may be referred to as the normal line of the first protective member251or the normal line of the second protective member252. As shown inFIG.7, a plurality of wire rods253having the Xm direction as a line direction are disposed along the Ym direction, and a plurality of wire rods253having the Ym direction as a line direction are disposed along the Xm direction, whereby the first protective member251is a filter configured in a mesh shape. AlthoughFIG.7shows an example in which the Xm direction and the Ym direction intersect at 90°, the present disclosure is not limited thereto, and the angle formed by the Xm direction and the Ym direction may be an angle other than 90°. As the material of the wire rod253, a metal material such as copper, iron, brass, or SUS, an alloy material, a synthetic resin such as nylon or polyester, or the like can be used. In particular, it is preferable to use a material having conductivity, and in this case, resistance to static electricity and electromagnetic waves can be obtained.

Further, a wire diameter W1 of the wire rod253is preferably less than the wavelength of ultrasonic waves. This suppresses the disadvantage that the ultrasonic waves are diffusely reflected by the wire rod253. In such a first protective member251, a void254surrounded by a pair of wire rods253adjacent to each other in the Xm direction and a pair of wire rods253adjacent to each other in the Ym direction is formed, and this void corresponds to a first hole portion according to the present disclosure through which ultrasonic waves pass. Similarly, in the second protective member252, the void254surrounded by a pair of wire rods253adjacent to each other in the Xm direction and a pair of wire rods253adjacent to each other in the Ym direction is formed, and this void corresponds to a second hole portion according to the present disclosure through which ultrasonic waves pass. In the present embodiment, in order to suppress the adhesion of foreign matter such as ink droplets and paper dust to the first ultrasonic sensor210and the second ultrasonic sensor220, it is preferable that the width of the void254, that is, the distance (open W2) between the adjacent wire rods253is set to 1 mm or less.

The distance between the center axes of the wire rods253is defined as a pitch W3, and a porosity S is defined by the following (1).
S=100×(W2/W3)2(1)

In the present embodiment, a porosity S is preferably 20% or more. When the distance to the sheet1is measured by the first ultrasonic sensor210and the second ultrasonic sensor220, the ultrasonic waves transmitted from the first ultrasonic sensor210and the second ultrasonic sensor220reach the sheet1, and the ultrasonic waves reflected by the sheet1need to be received by the first ultrasonic sensor210and the second ultrasonic sensor220again. In this case, when the sound pressure of the received ultrasonic wave decreases, the reception sensitivity of ultrasonic waves decreases, and the reception timing cannot be properly determined. Therefore, in order to suppress the decrease in the sound pressure of ultrasonic waves, it is preferable that the acoustic transmittance of the first protective member251and the second protective member252be 50% or more. Here, when the porosity S is less than 20%, the acoustic transmittance is less than 50%, and the reception sensitivity decreases. On the other hand, when the porosity S is 20% or more, the acoustic transmittance becomes 50% or more, and it is possible to suppress an excessive decrease in the sound pressure of the received ultrasonic waves.

The first holder261is a member for holding the first protective member251, and is attached to the first engaging portion304A provided on the holder holding portion304of the shield member300. The second holder262is a member that holds the second protective member252, and is attached to the second engaging portion304B provided on the holder holding portion304of the shield member300.

As shown inFIGS.4and5, the first holder261has a first holding surface263for holding the first protective member251. The first holding surface263is a plane inclined with respect to the Z direction, and the first protective member251is fixed along the first holding surface263. Thereby, in the first protective member251, the surface (first protective surface251A) facing the first ultrasonic sensor210is inclined with respect to the transmission and reception surface211of the first ultrasonic sensor210. That is, the first protective surface251A is inclined at an angle θ with respect to the Z direction. In addition, the first holding surface263is provided with a first passage hole261A through which ultrasonic waves pass.

The first holding surface263provided with the first protective member251is inclined so that the distance from the transmission and reception surface211of the first ultrasonic sensor210increases toward the +X side, for example. As a result, the first protective surface251A of the first protective member251provided on the first holding surface263is also inclined so that the distance between the first protective surface251A and the transmission and reception surface211increases toward the +X side.

The same applies to the second holder262, and the second holder262has a second holding surface264for holding the second protective member252as shown inFIG.4. The second holding surface264is provided with a second passage hole262A that allows ultrasonic waves to pass therethrough. Although not shown inFIG.5, the second holding surface264of the second holder262is, for example, a plane inclined with respect to the Z direction, like the first holding surface263, and the distance from the transmission and reception surface221of the second ultrasonic sensor220is inclined so as to increase toward the +X side. As a result, the surface (second protective surface252A) of the second protective member252provided on the second holding surface264of the second holder262facing the second ultrasonic sensor220also inclines so that the distance between the second protective surface252A and the transmission and reception surface221increases toward the +X side.

Positional Relationship Between Transmission and Reception Surfaces211and221and Opening Windows331and332

FIG.8is a view showing the positions of the transmission and reception surface211of the first ultrasonic sensor210, the first opening window331, and the first protective member251, and the shape of the ultrasonic beam, andFIG.9is a view showing the positions of the transmission and reception surface221, the second opening window332, and the second protective member252of the second ultrasonic sensor220, and the shape of the ultrasonic beam. As shown inFIG.8, in the ultrasonic apparatus200of the present embodiment, a distance ZS1between the transmission and reception surface211of the first ultrasonic sensor210and the first opening window331of the shield member300is shorter than a near-field limit distance ZNof the ultrasonic waves transmitted from the first ultrasonic sensor210. Therefore, the first protective member251is provided within the near-field limit distance ZN. Further, it is preferable that the distance from the first ultrasonic sensor210to the platen11is in the vicinity of the near-field limit distance ZN. As a result, ultrasonic waves with high sound pressure can be applied to the sheet1disposed on the platen11, and an S/N ratio of the received signal can be improved.

Further, as shown inFIG.8, a width STR1of the transmission and reception surface211of the first ultrasonic sensor210, an opening size SS1of the first opening window331, and an opening dimension Sm1when the first passage hole261A of the first holder261is projected on the XY plane satisfy the relationship of STR1≤Sm1≤SS1, and more preferably STR1<Sm1<SS1.

The same applies to the second ultrasonic sensor220, the second opening window332, and the second passage hole262A, as shown inFIG.9. That is, the distance ZS2between the transmission and reception surface221of the second ultrasonic sensor220and the second opening window332is shorter than the near-field limit distance ZNof the ultrasonic waves transmitted from the second ultrasonic sensor220, and the second protective member252is provided within the near-field limit distance ZN. In the present embodiment, ZS1=ZS2, but the distance ZS1between the first ultrasonic sensor210and the first opening window331and the distance ZS2between the second ultrasonic sensor220and the second opening window332may be a different distance. Further, it is preferable that the distance between the second ultrasonic sensor220and the platen11is in the vicinity of the near-field limit distance ZN. Further, the width STR2of the transmission and reception surface221of the second ultrasonic sensor220, the opening size SS2of the second opening window332, and the opening size Sm2when the second passage hole is projected on the XY plane satisfy the relationship of STR2≤Sm2≤SS2, and more preferably STR2<Sm2<SS2.

As described above, in the present embodiment, the distance ZS1from the first ultrasonic sensor210to the first opening window331and the distance ZS2from the second ultrasonic sensor220to the second opening window332are shorter than the near-field limit distance ZN. Within this near-field limit distance ZN, the beam diameter of the ultrasonic waves is approximately the same as the widths STR1and STR2of the transmission and reception surfaces211and221as shown inFIGS.8and9. Therefore, as described above, by setting the relationship of STR1≤Sm1≤SS1and STR2≤Sm2≤SS2, the reflection of ultrasonic waves on the first holder261and the second holder262and the reflection on the bottom surface portion330can be suppressed. Further, as the shield member300, in the configuration in which the bottom surface portion330is attachable to and detachable from the shield main body portion including the top surface portion310and the side surface portions321to324, after the ultrasonic sensors210and220, the circuit board240, and the like are provided inside the shield main body portion, the bottom surface portion330is attached to the shield main body portion. With such a configuration, the first opening window331and the second opening window332are easily affected by the positional balance during assembly of the ultrasonic apparatus200, and it is difficult to adjust the alignment when the bottom surface portion330is attached. On the other hand, by setting STR1<Sm1<SS1and STR2<Sm2<SS2, it is easy to adjust the alignment when attaching the bottom surface portion330to the shield body, and the positions of the first opening window331and the second opening window332can be suppressed from deviating from the position where the ultrasonic beam is formed.

Configuration for Suppressing Multiple Reflection of Ultrasonic Waves

Next, the influence of multiple reflection by the first protective member251will be described. Since the second protective member252has the same configuration as the first protective member251, the description here will be omitted or simplified.FIG.10is a view showing changes in the voltage value of the received signal when the distance Zm1from the transmission and reception surface211to the first protective member251is changed, in a plurality of patterns in which the disposition angle of the first protective member251is changed. InFIG.10, the angle formed between the normal line of the first protective surface251A and the Z direction is changed into three patterns of 0°, 10°, and 20°, and in each case, the distance Zm1between the first ultrasonic sensor210and the first protective member251is changed between 3 mm and 10 mm. InFIG.10, a signal A1 is a received signal when the normal line of the first protective surface251A and the Z direction are parallel to each other. A signal A2 is a received signal when the first angle θ formed between the normal line of the first protective surface251A and the Z direction is 10°. A signal A3 is a received signal when the first angle θ formed between the normal line of the first protective surface251A and the Z direction is 20°. The display of the signal A3 when the distance Zm1is changed from 3 mm to 5 mm is omitted in consideration of the visibility of the signal A2, but the same waveform as after 5 mm is obtained.

When the normal line of the first protective surface251A and the Z direction are parallel to each other, if the distance Zm1is changed as shown by the signal A1 inFIG.10, the voltage value (received voltage) of the received signal fluctuates greatly. That is, when the relationship between the distance Zm1and a wavelength λ of the ultrasonic wave is Zm=m×λ/2 (where m is an integer), the ultrasonic waves due to the multiple reflection components strengthen each other, and when the relationship between a distance L1and the wavelength λ of the ultrasonic wave is the distance Zm1={(2 m+1)/4}×λ, the ultrasonic waves due to the multiple reflection components weaken each other. As described above, when the variation in the voltage value of the received signal becomes large when the distance Zm1is changed, it means that the multiple reflection component of the ultrasonic wave is received by the first ultrasonic sensor210. In such a case, it is difficult to accurately detect the reception timing of the ultrasonic wave reflected by the sheet1due to the noise component of the ultrasonic wave that is multiply reflected.

On the other hand, when the first angle θ is set to 10° or more like the signals A2 and A3, the variation of the received signal when the distance Zm1is changed becomes small. This means that the multiple reflection component of the ultrasonic wave received by the first ultrasonic sensor210is reduced. That is, by increasing the first angle θ, noise due to multiple reflection components can be suppressed, and the reception timing of the ultrasonic waves reflected by the sheet1can be accurately detected.

FIG.11shows the measurement result of the magnitude of the received signal when the first ultrasonic sensor210receives the ultrasonic wave of the multiple reflection component, which is measured by changing the first angle θ of the first protective member251. As shown inFIG.11, when the first angle θ formed between the normal line of the first protective surface251A and the Z direction is increased, the voltage value of the received signal decreases.

In order to suppress the deterioration of the detection accuracy of the reception timing due to the multiple reflection, it is preferable to set the inclination angle of the first protective member251so that at least the voltage value of the received signal due to the multiple reflection becomes equal to or less than the half value of the received voltage when the first angle θ is 0°. In this case, as shown inFIG.11, by setting the first angle θ to 5° or more, the voltage value of the received signal can be equal to or less than the half value of the received signal when θ=0°, regardless of the distance Zm1.

Considering the strengthening or weakening of the ultrasonic waves due to the multiple reflection components described above, it is more preferable that the first angle θ of the first protective member251is 10° or more.FIG.12is a view showing a positional relationship between the first protective member251and the first ultrasonic sensor210. InFIG.12, the distance Zm1between the first ultrasonic sensor210and the first protective member251is the distance between the center point of the transmission and reception surface211of the first ultrasonic sensor210and the center point of the first protective member251. When the ultrasonic wave transmitted from the center point of the transmission and reception surface211in the Z direction is reflected by the first protective member251, the reflected ultrasonic wave is input at a position separated from the center point of the transmission and reception surface211by a distance Ld=Zm1·tan(2θ) in the same plane as the transmission and reception surface211.

Therefore, in order to prevent the ultrasonic waves reflected by the first protective member251from being received by the first ultrasonic sensor210, it is preferable to set the position and the inclination angle of the first protective member251so that the relationship between the width STR1of the transmission and reception surface211and the distance Ldis STR1/2<Ld. That is, it is preferable that the positional relationship between the width STR1of the transmission and reception surface211of the first ultrasonic sensor210and the first protective member251satisfies STR1<2Zm1·tan(2θ). It is more preferable to satisfy the positional relationship between the width STR1of the transmission and reception surface211of the first ultrasonic sensor210and the first protective member251satisfies STR1<Ld, that is, STR1<Zm1·tan(2θ). In this case, it is possible to further suppress the disadvantage that the ultrasonic wave transmitted from the first ultrasonic sensor210is reflected by the first protective member251and enters the transmission and reception surface211.

The above relationship also holds for the second ultrasonic sensor220and the second protective member252. Therefore, it is preferable that the positional relationship between the width STR2of the transmission and reception surface221of the second ultrasonic sensor220and the second protective member252satisfies STR2<Zm2·tan(2θ), and it is more preferable to satisfy STR2<Zm2·tan(2θ).

Further, in the embodiment, as shown inFIG.5, the first protective surface251A to which the ultrasonic wave from the first ultrasonic sensor210is input is inclined so as to face the second side surface portion322. That is, assuming that distance between any first point on the first protective surface251A and the transmission and reception surface211is L1, and the distance between the transmission and reception surface211and a second point on the +X side farther from the circuit board240than the first point is L2, L1<L2 is satisfied. In other words, the first protective member251is inclined so that the ultrasonic wave transmitted from the first ultrasonic sensor210in the Z direction is reflected by the first protective surface251A toward the second side surface portion322.

Although not shown inFIG.5, the second protective member252is also the same, and the second protective surface252A to which the ultrasonic wave from the second ultrasonic sensor220is input is inclined so as to face the second side surface portion322. That is, assuming that the distance between any third point on the second protective surface252A and the transmission and reception surface221is L3, and the distance between a fourth point on the +X side farther from the circuit board240than the third point and the transmission and reception surface221is L4, L3<L4 is satisfied. In other words, the second protective member252is inclined so that the ultrasonic wave transmitted from the second ultrasonic sensor220in the Z direction is reflected by the second protective surface252A toward the second side surface portion322.

As a result, it is possible to suppress the disadvantage that the ultrasonic wave transmitted from the first ultrasonic sensor210and reflected by the first protective member251is reflected by the circuit board240. That is, in the present embodiment, as described above, as shown inFIG.5, the first ultrasonic sensor210and the second ultrasonic sensor220are provided at a midpoint of the shield inner space from the first side surface portion321to the second side surface portion322. On the other hand, the circuit board240is disposed so as to be closer to the first side surface portion321than the midpoint of the shield inner space from the first side surface portion321to the second side surface portion322, and to be parallel to the first side surface portion321and the second side surface portion322. Therefore, the distance between the first ultrasonic sensor210and the second ultrasonic sensor220and the second side surface portion322is greater than the distance between the first ultrasonic sensor210and the second ultrasonic sensor220and the circuit board240.

Here, the case where the ultrasonic waves transmitted from the first ultrasonic sensor210and the second ultrasonic sensor220are reflected toward the circuit board240by the first protective member251and the second protective member252and the case where the ultrasonic waves are reflected on the second side surface portion322side will be compared. The circuit board240is disposed closer to the first ultrasonic sensor210and the second ultrasonic sensor220than the second side surface portion322. Therefore, in the former case, when the ultrasonic waves are reflected toward the circuit board240, a large amount of the ultrasonic waves re-reflected by the circuit board240are input to the first ultrasonic sensor210and the second ultrasonic sensor220, and the received signal has a lot of noise. On the other hand, in the latter, even when the ultrasonic waves are re-reflected by the second side surface portion322, the amount of ultrasonic waves input to the first ultrasonic sensor210and the second ultrasonic sensor220is smaller than that of the former, and the noise included in the received signal is also small.

Configuration of Controller160

As shown inFIG.2, the controller160includes an arithmetic portion161configured by a CPU (Central Processing Unit) and the like, and a storage portion162configured by a recording circuit such as a memory. The controller160is coupled to the supplier110, the transporter120, the heater130, the printer141, the movement mechanism150, and the ultrasonic apparatus200, and controls the overall operation of the printing apparatus100. The controller160is coupled to an interface portion (not shown), and is coupled to an external apparatus such as a personal computer via the interface portion. Then, the controller160receives the image data input from the external apparatus, controls each portion of the printing apparatus100, and forms an image on the sheet1based on the image data.

The storage portion162records various data for controlling the printing apparatus100and various programs. The arithmetic portion161functions as a first controller163, a detector164, a second controller165, and the like by reading and executing various programs stored in the storage portion162, as shown inFIG.2.

The first controller163controls the supplier110and the transporter120to transport the sheet1so that the predetermined position of the sheet1is located on the platen11. The first controller163also controls the movement mechanism150to move the carriage140and the ultrasonic apparatus200to a predetermined position on the platen11.

The detector164commands the ultrasonic apparatus200to perform ultrasonic measurement, and detects the occurrence of wrinkles based on the error signal from the ultrasonic apparatus200. The detection apparatus according to the present disclosure is configured by the ultrasonic apparatus200and the function as the detector164of the arithmetic portion161. Here, the method for detecting wrinkles in the present embodiment will be described in detail. As shown inFIG.2, in the ultrasonic apparatus200of the present embodiment, the first ultrasonic sensor210is disposed in the downstream and the second ultrasonic sensor220is disposed in the upstream along the Y direction, which is the transport direction of the sheet1. Further, since the ultrasonic apparatus200is fixed to the carriage140, the ultrasonic apparatus200can also be moved in the X direction by moving the carriage140by the movement mechanism150. Therefore, the first ultrasonic sensor210can perform ultrasonic wave transmission and reception processing at each position along the X direction in the downstream in the transport direction. Further, the second ultrasonic sensor220can perform ultrasonic wave transmission and reception processing at each position along the X direction in the upstream in the transport direction. Accordingly, the first control circuit241can calculate the first distance from the first ultrasonic sensor210to the sheet1at the downstream in the transport direction and at each position along the X direction, and the second control circuit242can calculate the second distance from the second ultrasonic sensor220to the sheet1at the upstream in the transport direction and at each position along the X direction. Further, the determination circuit243calculates the difference between the first distance and the second distance at each position in the X direction, and outputs an error signal when the difference exceeds a threshold value.

Therefore, when no error signal is input from the ultrasonic apparatus200, the detector164can determine that wrinkles are not detected in the sheet1at each position in the X direction, and can detect wrinkles in the sheet1in any position in the X direction when an error signal is input from the ultrasonic apparatus200.

FIGS.13to15are views showing examples of wrinkles in the sheet1detected by the detector164.FIGS.13to15show the amount wrinkles occurring in the sheet1with respect to the six locations C1(X1, Y1), C2(X2, Y1), C3(X3, Y1), C4(X1, Y2), C5(X2, Y2), and C6(X3, Y2), and black circles indicate locations with many wrinkles, white circles indicate locations with medium wrinkles, and double circles indicate locations with few wrinkles. For example, in the example ofFIG.13, this is a wrinkle that occurs when the ±X side edge of the sheet1is inclined with respect to the Y direction, which is the transport direction. Originally, the ±X edge of the sheet1is transported in a state of being parallel to the Y direction as shown inFIG.13. However, as shown inFIG.13, when the ±X side edge of the sheet1is inclined with respect to the Y direction due to impact or the like, and the sheet1is transported in the Y direction as it is, wrinkles (serpentine wrinkles) occur on the sheet1at the positions of C5 and C6 in the upstream in the Y direction and the positions of C3 in the downstream. In this case, for example, the occurrence of wrinkles cannot be detected only at the position of C1. On the other hand, in the present embodiment, the detector164can detect wrinkles because an error signal is output from the ultrasonic apparatus200when the ultrasonic apparatus200is moved to the position of X2.

The wrinkles on the sheet1may change depending on the type of the sheet1. For example,FIG.14shows an example of wrinkles when a wallpaper for a sign display is used as the sheet1, and in this example, wrinkles occur only at the position of C5. Therefore, the detector164can detect wrinkles because the ultrasonic apparatus200outputs an error signal when the ultrasonic apparatus200is moved to the position of X2. Further, the example ofFIG.15is an example of wrinkles when a woven fabric for a banner, which is also used as a banner, is used as the sheet, and many wrinkles occur at the position of C3, and medium wrinkles occur at the position of C6. Therefore, the detector164can detect wrinkles because the ultrasonic apparatus200outputs an error signal when the ultrasonic apparatus200is moved to the position of X3.

FIGS.13to15show examples of serpentine wrinkles, but the wrinkles that occur on the sheet1include, for example, wrinkles that occur when the sheet1is left in a high humidity environment, swelling wrinkles that occur when the sheet1made of a material having high rigidity and shrinkability is used, and wrinkles caused by the sticking of the sheet1due to static electricity, wrinkles that occur when the end surface of the roll paper floats up when roll paper is used as the sheet1, and the like. Since it is a wrinkle that causes unevenness on the surface of the sheet1, the wrinkles left alone change the first distance and the second distance due to unevenness at a plurality of locations along the X direction, and an error signal is output. Since wrinkles in which part of the sheet rises occur, an error signal is output from the ultrasonic apparatus200in the swelling wrinkles at the raised location. When sticking occurs due to static electricity, the ultrasonic apparatus200outputs an error signal at the position where the sticking occurs. The wrinkles occurred by the floating of the end surface of the roll paper cause an error signal to be output from the ultrasonic apparatus200at the location where the roll paper floats. Therefore, in the present embodiment, the detector164can suitably detect wrinkles with respect to any of the above wrinkles.

The second controller165controls the printer141to form an image on the sheet1when no wrinkles are detected by the detector164. Specifically, the second controller165forms an image on the sheet1in cooperation with the first controller163. That is, in the printing apparatus100, when image data is input from an external apparatus or the like, the first controller163transports the sheet1so that the image formation position of the sheet1is located on the platen11based on the image data and moves the carriage140in the X direction. Then, when the carriage is moved to the position based on the image data, the second controller165ejects ink of the color based on the image data to the image formation position to form dots. By repeating the above processing, the first controller163and the second controller165form an image on the sheet1. Further, the second controller165suspends the image forming processing when the detector164detects wrinkles during the formation of the image. This suppresses the disadvantage of wasted ink.

Operational Effects of Present Embodiment

The printing apparatus100of the present embodiment includes an ultrasonic apparatus200. The ultrasonic apparatus200includes a first ultrasonic sensor210, a second ultrasonic sensor220, and a circuit board240. The first ultrasonic sensor210and the second ultrasonic sensor220transmit ultrasonic waves to the sheet1, which is an object, and receive ultrasonic waves reflected by the sheet1. The circuit board240includes a first control circuit241, a second control circuit242, and a determination circuit243. The first control circuit241calculates the first distance between the first ultrasonic sensor210and the sheet1based on the time from the transmission timing of the ultrasonic waves obtained by the transmission and reception processing of the ultrasonic waves using the first ultrasonic sensor210to the reception timing, and the speed of sound. The second control circuit242calculates the second distance between the second ultrasonic sensor220and the sheet1based on the time from the transmission timing of the ultrasonic waves obtained by the transmission and reception processing of the ultrasonic waves using the second ultrasonic sensor220to the reception timing, and the speed of sound. The determination circuit243determines whether the difference between the first distance and the second distance is equal to or greater than a threshold value, and outputs an error signal when the difference is equal to or greater than the threshold value.

With such a configuration, the ultrasonic apparatus200calculates the distance from the sheet1at a plurality of locations on the sheet1, and outputs an error signal when the first distance and the second distance have a difference equal to or greater than the threshold value based on the distances calculated at the plurality of locations. Therefore, the wrinkles can be determined with higher accuracy than in the case where the presence or absence of wrinkles is determined by the ultrasonic wave transmission and reception processing for a single location on the sheet1.

The ultrasonic apparatus200of the present embodiment further includes the conductive shield member300in which the first ultrasonic sensor210and the second ultrasonic sensor220are provided. The shield member300includes the first opening window331provided between the first ultrasonic sensor210and the sheet1transported to the platen11. The shield member300also includes the second opening window332provided between the second ultrasonic sensor220and the sheet1transported to the platen11.

Therefore, the first ultrasonic sensor210and the second ultrasonic sensor220are surrounded by the conductive shield member, thereby protecting the first ultrasonic sensor210and the second ultrasonic sensor220from external electromagnetic waves. Therefore, it is possible to suppress the disadvantage that the noise signal due to the electromagnetic wave is superimposed on the received signals output from the first ultrasonic sensor210and the second ultrasonic sensor220. Further, by providing the first opening window331and the second opening window332, the shield member300does not hinder the transmission and reception of ultrasonic waves between the first ultrasonic sensor210and the sheet1, and the transmission and reception of ultrasonic waves between the second ultrasonic sensor220and the sheet1.

In the ultrasonic apparatus200of the present embodiment, the distance ZS1between the first opening window331and the transmission and reception surface211of the first ultrasonic sensor210is shorter than the near-field limit distance ZNof the first ultrasonic sensor210. The distance ZS2between the second opening window332and the transmission and reception surface221of the second ultrasonic sensor220is shorter than the near-field limit distance ZNof the second ultrasonic sensor220. That is, in the present embodiment, the first opening window331is provided within the near-field limit distance ZNfrom the transmission and reception surface211, and the second opening window332is provided within the near-field limit distance ZNfrom the transmission and reception surface221.

As a result, it is possible to apply an ultrasonic wave having a strong sound pressure in the vicinity of the near-field limit distance ZNto the sheet1from the first ultrasonic sensor210and the second ultrasonic sensor220, and to improve the S/N ratio in ultrasonic wave transmission and reception processing.

In the ultrasonic apparatus200of the present embodiment, the circuit board240is provided inside the shield member300. Therefore, it is possible to suppress the influence of external electromagnetic waves on the circuit board240, and it is possible to suppress deterioration in accuracy of ultrasonic wave transmission and reception processing due to noise.

In the ultrasonic apparatus200of the embodiment, the shield member300includes the first side surface portion321that is parallel to the YZ plane including the Y direction in which the first ultrasonic sensor210and the second ultrasonic sensor220are arranged, and the Z direction in which ultrasonic waves are transmitted and received by the first ultrasonic sensor210and the second ultrasonic sensor220, and the second side surface portion322facing the first side surface portion321. The circuit board240is disposed such that the projected area of the circuit board240projected on the YZ plane is 70% or more of the area of the circuit board240. Accordingly, in the ultrasonic apparatus200, the ultrasonic apparatus200can be downsized as compared with the case where the circuit board240is disposed parallel to the XZ plane or the XY plane.

In the present embodiment, the circuit board240is disposed closer to the first side surface portion321than the midpoint between the first side surface portion321and the second side surface portion322. Further, between the first opening window331and the first ultrasonic sensor210, the first protective member251having the first protective surface251A provided with a plurality of first hole portions (voids254) through which ultrasonic waves pass is provided. Further, between the second opening window332and the second ultrasonic sensor220, the second protective member252having the second protective surface252A provided with a plurality of second hole portions (voids254) through which ultrasonic waves pass is provided. The first protective surface251A is inclined to a direction in which the ultrasonic wave transmitted from the first ultrasonic sensor210is reflected toward the second side surface portion322with respect to the ultrasonic wave transmission and reception surface211of the first ultrasonic sensor210. The second protective surface252A is inclined to a direction in which the ultrasonic wave transmitted from the second ultrasonic sensor220is reflected toward the second side surface portion322with respect to the ultrasonic wave transmission and reception surface221of the second ultrasonic sensor220.

As a result, with the first protective member251and the second protective member252, it is possible to suppress the entry of foreign matter such as ink droplets and paper dust into the inside of the shield member300, and it is possible to suppress adhesion of foreign matter to the first ultrasonic sensor210and the second ultrasonic sensor220. Therefore, it is possible to suppress the deterioration of the performance of the first ultrasonic sensor210or the second ultrasonic sensor220, that is, the decrease in the sound pressure of the transmitted ultrasonic wave and the decrease in the reception sensitivity of the ultrasonic wave. Further, since the first protective surface251A is inclined with respect to the transmission and reception surface211of the first ultrasonic sensor210, it is possible to suppress the disadvantage that ultrasonic waves are multiply reflected between the first ultrasonic sensor210and the first protective member251. Similarly, since the second protective surface252A is inclined with respect to the transmission and reception surface221of the second ultrasonic sensor220, it is possible to suppress the disadvantage that ultrasonic waves are multiply reflected between the second ultrasonic sensor220and the second protective member252. Accordingly, the ultrasonic apparatus200can suppress the disadvantage that a noise signal due to the occurrence of multiple reflection is superimposed on a received signal, and the first control circuit241and the second control circuit242can accurately calculate the first distance and the second distance. Further, part of the ultrasonic waves transmitted from the first ultrasonic sensor210and the second ultrasonic sensor220is reflected toward the second side surface portion322by the first protective surface251A and the second protective surface252A. As a result, it is possible to suppress the disadvantage that the ultrasonic waves that are noise components are input to the first ultrasonic sensor210and the second ultrasonic sensor220. That is, when the ultrasonic waves reflected by the first protective surface251A and the second protective surface252A travel toward the circuit board240that is close to the first ultrasonic sensor210and the second ultrasonic sensor220, most of the ultrasonic waves re-reflected by the circuit board240enter the first ultrasonic sensor210and the second ultrasonic sensor220. Since this ultrasonic wave is not the ultrasonic wave reflected by the sheet1, the ultrasonic wave becomes a noise component. On the other hand, in the present embodiment, part of the ultrasonic waves transmitted from the first ultrasonic sensor210and the second ultrasonic sensor220is reflected by the first protective surface251A and the second protective surface252A toward the second side surface portion322that is farther from the first ultrasonic sensor210and the second ultrasonic sensor220than the circuit board240. Therefore, compared to the case where the ultrasonic waves are reflected by the circuit board240, the amount of ultrasonic waves reflected by the second side surface portion322and input to the first ultrasonic sensor210and the second ultrasonic sensor220is reduced. Therefore, the ultrasonic apparatus200can suppress a decrease in the S/N ratio of the received signal, and can perform ultrasonic wave transmission and reception processing with high accuracy.

The ultrasonic apparatus200of the present embodiment includes the first holder261to which the first protective member251is attached and the second holder262to which the second protective member252is attached. The first holder261and the second holder262are detachably provided on the holder holding portion304of the shield member300. Therefore, when the first protective member251and the second protective member252are replaced, the first holder261and the second holder262can be easily removed from the shield member300, and the ultrasonic apparatus200can be easily maintained.

In the ultrasonic apparatus200of the present embodiment, the first holder261includes the first passage hole261A through which the ultrasonic waves that passed through the first protective member251pass, and the second holder262includes the second passage hole262A through which the ultrasonic waves that passed through the second protective member252pass. The opening size SS1of the first opening window331, the opening size Sm1of the first passage hole261A, and the width STR1of the transmission and reception surface211of the first ultrasonic sensor210satisfy the relationship of STR1≤Sm1≤SS1. In addition, the opening size SS2of the second opening window332, the opening size Sm2of the second passage hole262A, and the width STR2of the transmission and reception surface221of the second ultrasonic sensor220satisfy the relationship of STR2≤Sm2≤SS2. Thereby, the ultrasonic waves transmitted from the first ultrasonic sensor210and the second ultrasonic sensor220are not reflected by the first holder261, the second holder262, and the shield member300, and multiple reflection can be suppressed. Further, since it is possible to suppress the decrease in the sound pressure of the ultrasonic wave used for the measurement, it is possible to improve the S/N ratio of the received signal.

The printing apparatus100of the present embodiment includes the ultrasonic apparatus200and the controller160. Then, the controller160functions as the detector164that detects wrinkles, which is one of the abnormalities of the sheet1, based on the error signal output from the ultrasonic apparatus200. Accordingly, the printing apparatus100can detect the wrinkles occurring on the sheet1based on the error signal output from the ultrasonic apparatus200.

The printing apparatus100according to the present embodiment includes a transporter120that transports the sheet1along the Y direction which is the transport direction. The second ultrasonic sensor220provided in the ultrasonic apparatus200is disposed in the upstream in the Y direction with respect to the disposition position of the first ultrasonic sensor210. That is, the first ultrasonic sensor210and the second ultrasonic sensor220are disposed side by side along the Y direction. As a result, the printing apparatus100can suitably detect wrinkles that occur only in the upstream in the transport direction of the sheet1and wrinkles that occur only in the downstream. Accordingly, for example, wrinkles of the sheet1having various patterns as shown inFIGS.13to15can be detected.

The printing apparatus100of the present embodiment includes the movement mechanism150for moving the ultrasonic apparatus200in the X direction intersecting with the Y direction. Accordingly, by moving the first ultrasonic sensor210and the second ultrasonic sensor220disposed side by side in the Y direction in the X direction, ultrasonic waves can be scanned along the X direction, and wrinkles can be detected over a wide area of the sheet1.

The printing apparatus100of the present embodiment includes a printer141that forms an image on the sheet1, and the first controller163and the second controller165control printing by the printer141based on the wrinkle detection result by the detector164. As a result, when the sheet1has wrinkles, printing can be interrupted, thereby suppressing ink consumption for printing.

Second Embodiment

In the above-described first embodiment, in the ultrasonic apparatus200, an example in which the first protective member251and the second protective member252are inclined so as to reflect ultrasonic waves toward the second side surface portion322on which the circuit board240is not disposed has been shown. On the other hand, in the ultrasonic apparatus200of the second embodiment, the inclination directions of the first protective member251and the second protective member252differ from those of the first embodiment. In the following description, the same reference numerals will be given to the configurations already described, and the description thereof will be omitted or simplified.

FIG.16is a cross-sectional view of an ultrasonic apparatus200A of the second embodiment taken along the YZ plane. As shown inFIG.16, the ultrasonic apparatus200A of the present embodiment includes a first ultrasonic sensor210, a second ultrasonic sensor220, a first pedestal portion231, a second pedestal portion232, a circuit board240, a first protective member251, a second protective member252, a first holder271, a second holder272, and a shield member300. The first ultrasonic sensor210is fixed to the first pedestal portion231as in the first embodiment. Then, by fixing the first pedestal portion231to the shield member300, the first ultrasonic sensor210is provided inside the shield member300so as to face the first opening window331. The second ultrasonic sensor220is fixed to the second pedestal portion232as in the first embodiment. Then, by fixing the second pedestal portion232to the shield member300, the second ultrasonic sensor220is provided inside the shield member300so as to face the second opening window332. Similar to the first embodiment, the circuit board240is disposed parallel to the first side surface portion321and the second side surface portion322, and closer to the first side surface portion321than the midpoint between the first side surface portion321and the second side surface portion322.

The first protective member251is fixed to the first holding surface273of the first holder271. The first holding surface273of the first holder271is provided with a first passage hole271A penetrating in the Z direction. Then, the first holder271is engaged with the first engaging portion304A provided in the holder holding portion304of the shield member300, as in the first embodiment. Accordingly, the first protective member251is disposed between the first ultrasonic sensor210and the first opening window331. The second protective member252is fixed to the second holding surface274of the second holder272. The second holding surface274of the second holder272is provided with a second passage hole272A penetrating in the Z direction. Then, the second holder272is engaged with the second engaging portion304B provided in the holder holding portion304of the shield member300, as in the second embodiment. Accordingly, the second protective member252is disposed between the second ultrasonic sensor220and the second opening window332.

Here, in the present embodiment, the first protective member251held by the first holding surface273of the first holder271is inclined so that the distance from the transmission and reception surface211of the first ultrasonic sensor210increases toward the +Y side. That is, when the distance between any fifth point of the first protective surface251A and the transmission and reception surface211is L5, and the distance between a sixth point on the +Y side farther from the second ultrasonic sensor220than the fifth point and the transmission and reception surface211is L6, L5<L6 is satisfied. In other words, the first protective member251is inclined so that the ultrasonic wave transmitted from the first ultrasonic sensor210in the Z direction is reflected by the first protective surface251A toward the third side surface portion323opposite to the second ultrasonic sensor220.

The second protective member252held by the second holding surface274of the second holder272is inclined so that the distance between the second protective surface252A and the transmission and reception surface221increases toward the −Y side. That is, when the distance between any seventh point of the second protective surface252A and the transmission and reception surface221is L7, and the distance between an eighth point on the Y side farther from the first ultrasonic sensor210than the seventh point and the transmission and reception surface221is L8, L7<L8 is satisfied. In other words, the second protective member252is inclined so that the ultrasonic waves transmitted from the second ultrasonic sensor220in the Z direction are reflected by the second protective surface252A toward the fourth side surface portion324opposite to the first ultrasonic sensor210.

Thus, in the present embodiment, it is possible to suppress the disadvantage that the ultrasonic waves transmitted from the first ultrasonic sensor210are input to the second ultrasonic sensor220, and the ultrasonic waves transmitted from the second ultrasonic sensor220are input to the first ultrasonic sensor210.

Operational Effects of Present Embodiment

The present embodiment has the same operational effects as the first embodiment, and further has the following operational effects. In the ultrasonic apparatus200of the present embodiment, the first protective surface251A of the first protective member251is inclined with respect to the transmission and reception surface211of the first ultrasonic sensor210so as to reflect the ultrasonic waves transmitted from the first ultrasonic sensor in a direction away from the second ultrasonic sensor220. Further, the second protective surface252A of the second protective member252is inclined with respect to the transmission and reception surface221of the second ultrasonic sensor220so as to reflect the ultrasonic waves transmitted from the second ultrasonic sensor220in a direction away from the first ultrasonic sensor210. For this reason, even when the ultrasonic wave transmitted from the first ultrasonic sensor210is reflected by the first protective member251, the input of the reflected ultrasonic wave to the second ultrasonic sensor220can be suppressed. Further, even when the ultrasonic wave transmitted from the second ultrasonic sensor220is reflected by the second protective member252, the input of the reflected ultrasonic wave to the first ultrasonic sensor210can be suppressed. This suppresses the disadvantage that the received signal contains noise, and the circuit board240can accurately calculate the first distance and the second distance.

MODIFICATION EXAMPLE

The present disclosure is not limited to the above-described embodiments, and modifications, improvements, or the like within the scope of achieving the object of the present disclosure are included in the present disclosure.

Modification Example 1

In the first embodiment and the second embodiment, an example in which two ultrasonic sensors, the first ultrasonic sensor210and the second ultrasonic sensor220, are provided along the Y direction has been shown, but the present disclosure is not limited thereto. For example, three or more ultrasonic sensors may be provided along the Y direction. In this case, the circuit board240is provided with a sensor control circuit for each ultrasonic sensor. Each sensor control circuit causes the corresponding ultrasonic sensor to perform ultrasonic wave transmission and reception processing, and calculates the distance from the ultrasonic sensor to the sheet1based on the transmission and reception result. In addition, the determination circuit243outputs an error signal when any one of the distances between the ultrasonic sensors and the sheet1has a difference having the threshold value or more with respect to the distance measured by another ultrasonic sensor.

A plurality of ultrasonic sensors may be provided along the X direction, or a plurality of ultrasonic sensors may be provided in each of the Y direction and the X direction. In the case where a large number of ultrasonic sensors are disposed along each of the X direction and the Y direction, a movement mechanism for moving the ultrasonic apparatus may not be required.

Modification Example 2

In the first and second embodiments described above, the rectangular parallelepiped shield member300having the top surface portion310, the side surface portions321to324, and the bottom surface portion330is illustrated, but the configuration of the shield member is not limited thereto. For example, the shield member may be formed in another shape such as a cylindrical shape.

Modification Example 3

In the first embodiment and the second embodiment described above, a configuration in which the first ultrasonic sensor210, the second ultrasonic sensor220, and the circuit board240are provided inside one shield member300has been illustrated, but for example, the configuration may include a first shield member in which the first ultrasonic sensor210is provided, a second shield member in which the second ultrasonic sensor220is provided, and a third shield member in which the circuit board240is provided.

Modification Example 4

Although the ultrasonic apparatus200is fixed to the carriage140in the first and second embodiments, the ultrasonic apparatus200may be provided separately from the carriage140. In this case, it is preferable to separately provide a second movement mechanism for moving the ultrasonic apparatus200in the X direction.

Modification Example 5

In the above-described first and second embodiments, an example in which the printing apparatus100also functions as a detection apparatus including the ultrasonic apparatus200has been shown, but the present disclosure is not limited thereto. For example, an image scanner or the like that captures an image printed on a sheet that is an object as image data may be configured to include the detection apparatus. In such an image scanner, in order to read the image on the sheet, the sheet is transported to the image reading position, and image reading processing is performed by the scanner at the image reading position. At this time, when the sheet has wrinkles at the image reading position, the image cannot be properly captured, and the wrinkles are reflected in the captured image. Therefore, the ultrasonic apparatus according to the present disclosure may be incorporated in such an image scanner to detect wrinkles on the sheet at the image reading position.

Modification Example 6

In the above-described first and second embodiments, the detection apparatus that detects the wrinkles of an object as an abnormality by using the ultrasonic apparatus200is illustrated, but the disclosure is not limited thereto. For example, the ultrasonic apparatus200may be incorporated in a distance measuring apparatus that measures the distance to the object. In this case, when an error signal is output from the circuit board of the ultrasonic apparatus200, the distance measuring apparatus determines that the distance measuring accuracy is low and stops the measurement. When an error signal is not output, the distance measuring apparatus outputs the average of the first distance and the second distance as the distance between the ultrasonic apparatus and the object.

Modification Example 7

In the first and second embodiments, an example in which the width STR1of the transmission and reception surface211of the first ultrasonic sensor210, the opening size SS1of the first opening window331, and the opening size Sm1of the first passage hole261A satisfy the relationship of STR1Sm1≤SS1has been shown, but the present disclosure is not limited thereto. For example, a plurality of ultrasonic transducers Tr constituting the first ultrasonic sensor210may be driven independently of each other, and the circuit board240may control the drive timing of each ultrasonic transducer Tr to form an ultrasonic beam that converges at a predetermined focus position. In this case, by controlling the first ultrasonic sensor210so that the platen11is at the focus position, the beam diameter of the ultrasonic waves becomes smaller toward the platen11. Therefore, the first opening window331and the first passage hole261A may be provided so as to satisfy STR1≥Sm1≥SS1. The relationship between the width STR2of the transmission and reception surface221of the second ultrasonic sensor220, the opening size SS2of the second opening window332, and the opening size Sm2of the second passage hole262A is the same.

Modification Example 8

In the first and second embodiments described above, an example in which the relationship between the distance ZS1between the transmission and reception surface211of the first ultrasonic sensor210and the first opening window331and the near-field limit distance ZNof the ultrasonic waves transmitted from the first ultrasonic sensor210satisfies ZS1<ZNhas been shown.

On the other hand, ZS1=ZNmay be set. In the case of long-distance sound waves, the sound pressure distribution in the beam cross section of an ultrasonic beam becomes a distribution in which the sound pressure becomes weaker toward the periphery around the transmission center axis of the ultrasonic wave, that is, a simple sound pressure distribution. Therefore, when the sound pressure of the ultrasonic waves transmitted from the first ultrasonic sensor210is sufficiently large and the sound pressure in the far field can be maintained above a predetermined value, the distance ZS1between the first opening window331and the transmission and reception surface211of the first ultrasonic sensor210may have the same dimension as the near-field limit distance ZN, or may be longer than the near-field limit distance ZN. The same applies to the distance between the second ultrasonic sensor220and the second opening window332.

Modification Example 9

In the first embodiment and the second embodiment, the configuration in which the first protective member251is held by the first holder261and the second protective member252is held by the second holder262has been exemplified, but the first protective member251and the second protective member252may be directly fixed to the vicinity of the first opening window331and the second opening window332of the shield member300.

Also, an example is shown in which the first holders261and271, and the second holders262and272are detachably attached to the holder holding portion304of the shield member300, but the first holders261and271, and the second holders262and272may be fixed to the holder holding portion304.

Modification Example 10

Although the circuit board240is provided parallel to the first side surface portion321and the second side surface portion322and in the vicinity of the first side surface portion321, the present disclosure is not limited thereto. For example, the circuit board240may be provided at a midpoint between the first side surface portion321and the second side surface portion322. Further, as described in Modification Example 1, when the plurality of ultrasonic sensors are disposed along the X direction, the circuit board240is disposed parallel to the third side surface portion323and the fourth side surface portion324. Further, when the plurality of ultrasonic sensors are disposed in an array along the X direction and the Y direction, the circuit board240may be disposed in the vicinity of the top surface portion310and parallel to the top surface portion310.

Overview of the Disclosure

According to the first aspect, there is provided an ultrasonic apparatus including a first ultrasonic sensor that transmits an ultrasonic wave to an object and receives the ultrasonic wave reflected by the object, a second ultrasonic sensor that transmits an ultrasonic wave to the object and receives the ultrasonic wave reflected by the object, an error output portion that outputs an error signal when the difference between a first distance between the first ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the first ultrasonic sensor and a second distance between the second ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the second ultrasonic sensor is equal to or greater than a threshold value.

As a result, the ultrasonic apparatus can detect an abnormality in an object and output an error signal by performing ultrasonic wave transmission and reception processing at a plurality of positions of the object. In this case, by transmitting the ultrasonic waves to one location of the object, it is possible to determine an abnormality more accurately than the ultrasonic apparatus of related art that detects an abnormality of the object.

The ultrasonic apparatus of the first aspect further includes a conductive shield member in which the first ultrasonic sensor and the second ultrasonic sensor are provided, and it is preferable that the shield member includes a first opening window and a second opening window, the first opening window is provided between the first ultrasonic sensor and the object, and the second opening window is provided between the second ultrasonic sensor and the object.

As a result, the ultrasonic apparatus can apply an ultrasonic wave having a strong sound pressure in the vicinity of the near-field limit distance to the object from the first ultrasonic sensor and the second ultrasonic sensor, and can improve the S/N ratio in the ultrasonic wave transmission and reception processing.

In the ultrasonic apparatus of this aspect, it is preferable that a distance between the first opening window and a transmission and reception surface of the first ultrasonic sensor is shorter than a near-field limit distance of the first ultrasonic sensor, and a distance between the second opening window and a transmission and reception surface of the second ultrasonic sensor is shorter than a near-field limit distance of the second ultrasonic sensor.

As a result, the ultrasonic apparatus can apply an ultrasonic wave having a strong sound pressure in the vicinity of the near-field limit distance to the object from the first ultrasonic sensor and the second ultrasonic sensor, and can improve the S/N ratio in the ultrasonic wave transmission and reception processing.

The ultrasonic apparatus according to the present aspect includes the circuit board that is provided with the error output portion, and it is preferable that the circuit board is provided inside the shield member. Therefore, the ultrasonic apparatus can suppress the influence of external electromagnetic waves on the circuit board, and can suppress deterioration in the accuracy of ultrasonic wave transmission and reception processing due to noise.

In the ultrasonic apparatus according to the present aspect, it is preferable that the shield member includes a first side surface portion parallel to a plane including a first direction in which the first ultrasonic sensor and the second ultrasonic sensor are arranged, and a transmission and reception direction of ultrasonic waves in which ultrasonic waves are transmitted from the first ultrasonic sensor and the second ultrasonic sensor, and a second side surface portion facing the first side surface portion, the circuit board is disposed closer to the first side surface portion than a midpoint between the first side surface portion and the second side surface portion, a first protective member having a first protective surface provided with a plurality of first hole portions for passing ultrasonic waves is provided between the first opening window and the first ultrasonic sensor, a second protective member having a second protective surface provided with a plurality of second hole portions for passing ultrasonic waves is provided between the second opening window and the second ultrasonic sensor, the first protective surface is inclined with respect to the transmission and reception surface of the first ultrasonic sensor in a direction in which ultrasonic waves transmitted from the first ultrasonic sensor are reflected toward the second side surface portion, and the second protective surface is inclined with respect to the transmission and reception surface of the second ultrasonic sensor in a direction in which ultrasonic waves transmitted from the second ultrasonic sensor are reflected toward the second side surface portion.

As a result, the first ultrasonic sensor and the second ultrasonic sensor can be protected by the first protective member and the second protective member. That is, it is possible to suppress the entry of foreign matter into the inside of the shield member through the first opening window and the second opening window, and to prevent the foreign matter from adhering to the first ultrasonic sensor and the second ultrasonic sensor. In addition, when such a first protective member or a second protective member is provided, part of the ultrasonic waves transmitted from the first ultrasonic sensor and the second ultrasonic sensor is reflected by the first protective surface and the second protective surface. Here, in the present aspect, the circuit board is disposed closer to the first side surface portion than the midpoint between the first side surface portion and the second side surface portion. Then, part of the ultrasonic waves reflected by the first protective surface and the second protective surface is reflected toward the second side surface portion opposite to the first side surface portion where the circuit board is disposed in close proximity. With such a configuration, it is possible to suppress the disadvantage that part of the ultrasonic waves reflected by the first protective surface and the second protective surface is multiply reflected in the shield and returns to the ultrasonic sensor. That is, when part of the ultrasonic waves reflected by the first protective surface or the second protective surface is directed to the first side surface portion, the ultrasonic waves are reflected on the circuit board disposed closer to the first ultrasonic sensor and the second ultrasonic sensor than the first side surface portion. In this case, the amount of ultrasonic components that are re-reflected by the circuit board and enter the ultrasonic sensor increases. On the other hand, the second side surface portion is farther from the first ultrasonic sensor and the second ultrasonic sensor than the circuit board. Therefore, even if the ultrasonic waves are re-reflected on the second side surface portion, compared to the case where the ultrasonic waves are re-reflected on the circuit board, the ultrasonic component entering the first ultrasonic sensor or the second ultrasonic sensor can be reduced. Therefore, it is possible to suppress an increase in noise due to an unnecessary reflected ultrasonic wave component, and it is possible to suppress a decrease in the S/N ratio of the received signal.

In the ultrasonic apparatus according to the present aspect, it is preferable that the shield member includes a first side surface portion parallel to a plane including a first direction in which the first ultrasonic sensor and the second ultrasonic sensor are arranged, and a transmission and reception direction of ultrasonic waves in which ultrasonic waves are transmitted from the first ultrasonic sensor and the second ultrasonic sensor, and a second side surface portion facing the first side surface portion, and the projected area of the circuit board onto the plane is 70% or more of the area of the circuit board. That is, it is preferable that the angle formed by the board surface of the circuit board and the plane parallel to the first side surface portion and the second side surface portion is 0° or more and 45° or less. This makes it possible to reduce the size of the ultrasonic apparatus as compared with the case where the circuit board is disposed orthogonal to the direction in which the first ultrasonic sensor and the second ultrasonic sensor are disposed.

In the ultrasonic apparatus of the present aspect, it is preferable that a first protective member having a plurality of first hole portions for passing ultrasonic waves is provided between the first opening window and the first ultrasonic sensor, and a second protective member having a plurality of second hole portions for passing ultrasonic waves is provided between the second opening window and the second ultrasonic sensor.

As a result, the first protective member and the second protective member can suppress the entry of foreign matter such as ink droplets and paper dust into the inside of the shield member, and can suppress adhesion of foreign matter to the first ultrasonic sensor and the second ultrasonic sensor. Therefore, it is possible to suppress the deterioration of the performance of the first ultrasonic sensor and the second ultrasonic sensor, that is, the decrease in the sound pressure of the transmitted ultrasonic wave and the decrease in the reception sensitivity of the ultrasonic wave.

In the ultrasonic apparatus of the present aspect, it is preferable that the first protective member includes a first protective surface provided with the plurality of first hole portions, the first protective surface is inclined with respect to the transmission and reception surface of the first ultrasonic sensor, the second protective member includes a second protective surface provided with the plurality of second hole portions, and the second protective surface is inclined with respect to the transmission and reception surface of the second ultrasonic sensor.

As a result, the ultrasonic apparatus can suppress the disadvantage that ultrasonic waves are multiply reflected between the first ultrasonic sensor and the first protective member, and can suppress the disadvantage that ultrasonic waves are multiply reflected between the second ultrasonic sensor220and the second protective member252. Therefore, the ultrasonic apparatus can suppress the disadvantage that the noise signal due to the occurrence of multiple reflection is superimposed on the received signal, and can accurately calculate the first distance and the second distance based on the ultrasonic wave transmission and reception processing by the first ultrasonic sensor and the second ultrasonic sensor.

In the ultrasonic apparatus of the present aspect, it is preferable that the first protective surface is inclined with respect to the transmission and reception surface of the first ultrasonic sensor so as to reflect the ultrasonic waves transmitted from the first ultrasonic sensor in a direction away from the second ultrasonic sensor, and the second protective surface is inclined with respect to the transmission and reception surface of the second ultrasonic sensor so as to reflect the ultrasonic waves transmitted from the second ultrasonic sensor in a direction away from the first ultrasonic sensor.

As a result, even when the ultrasonic wave transmitted from the first ultrasonic sensor is reflected by the first protective member, it is possible to suppress the disadvantage that the reflected ultrasonic wave is input to the second ultrasonic sensor. Further, even when the ultrasonic wave transmitted from the second ultrasonic sensor is reflected by the second protective member, it is possible to suppress the disadvantage that the reflected ultrasonic wave is input to the first ultrasonic sensor. As a result, the disadvantage that the received signal contains noise can be suppressed, and the measurement accuracy of the ultrasonic apparatus can be improved.

The ultrasonic apparatus according to the present aspect includes a first holder to which the first protective member is attached, and a second holder to which the second protective member is attached, and it is preferable that the first holder and the second holder are detachably attached to the shield member.

Thus, when the first protective member and the second protective member are replaced, the first holder and the second holder can be easily removed from the shield member, and the ultrasonic apparatus can be easily maintained.

In the ultrasonic apparatus200according to the present aspect, it is preferable that the first holder includes a first passage hole through which ultrasonic waves that passed through the first protective member pass, the second holder includes a second passage hole through which ultrasonic waves that passed through the second protective member pass, an opening size SS1of the first opening window, an opening size Sm1of the first passage hole, and a width STR1of the transmission and reception surface of the first ultrasonic sensor satisfy STR1Sm1≤SS1, and an opening size SS2of the second opening window, an opening size Sm2of the second passage hole, and a width STR2of the transmission and reception surface of the second ultrasonic sensor satisfy STR2≤Sm2≤SS2.

As a result, the ultrasonic waves transmitted from the first ultrasonic sensor and the second ultrasonic sensor are not reflected by the first holder, the second holder and the shield member, and multiple reflection can be suppressed. Further, it is possible to suppress a decrease in the sound pressure of ultrasonic waves input to the object, and it is possible to improve the S/N ratio of the received signal.

The detection apparatus of the second aspect includes the ultrasonic apparatus of the first aspect, and a detector that detects an abnormality of the object based on the error signal output from the ultrasonic apparatus. Accordingly, the detection apparatus can detect the abnormality of the object based on the error signal output from the ultrasonic apparatus.

The detection apparatus according to the present aspect includes a transport mechanism for transporting the object along a predetermined transport direction, and it is preferable that the second ultrasonic sensor is disposed on an upstream of a disposition position of the first ultrasonic sensor in the transport direction. Accordingly, the detection apparatus can suitably detect an abnormality that occurs when an object is transported and that occurs only in the upstream in the transport direction, and an abnormality that occurs only in the downstream.

In the detection apparatus according to the present aspect, it is preferable to further include a movement mechanism for moving the ultrasonic apparatus in a direction intersecting with the transport direction. Thereby, by moving the first ultrasonic sensor and the second ultrasonic sensor disposed side by side in the transport direction in a direction intersecting the transport direction, it is possible to detect an abnormality of the object in a wide range.

According to a third aspect, there is provided a printing apparatus that includes a detection apparatus according to the second aspect and a printer that forms an image on the object, and controls printing by the printer based on a detection result of the abnormality by the detector. As a result, when the object has an abnormality such as wrinkles, printing by the printer can be interrupted, thereby suppressing ink consumption for printing.