Patent Description:
For example, <CIT> is an example of an image reading device that scans an image of a document. The image reading device feeds a document set on a document support, which is an example of a placement section, by rotating a feed roller pair.

When the tilt angle of the document is greater than a threshold value, the image reading device determines that a skew error has occurred and stops operation. The image reading device changes the tilt angle, which is used to determine the occurrence of the skew error, according to the width of the document. In other words, when the document width is greater than the threshold value, the image reading device determines that the skew error has occurred at a smaller skew angle than when the document width is smaller than that threshold value.

For example, atypical documents such as receipts vary in length from document to document. If a long length document is skewed, the rear end of the document will be displaced greatly even if the tilt angle is small. The feed roller presses the document in the nip region and rotates to feed the document. When feeding multiple documents in sequence, if the side edge portion of the preceding document is displaced into the nip region, the subsequent document may contact the feed roller and skew before the preceding document has finished feeding.

<CIT> discloses an image-reading device comprising a mask setting unit for setting mask region continuously and dynamically from target line to another target line on which detection of edge pixel ends in direction when edge pixel is included in edge image data.

A reading device that solves the above problem includes a placement section on which a plurality of documents is placed; a feed roller that feeds the documents from the placement section; a separation section that separates the documents being fed by the feed roller; a reading section that scans the documents being transported in a transport direction; a control section that determines a transport error of the documents; and a detection section that detects the documents that are placed on the placement section; wherein assuming that a document fed first is a preceding document and that a document fed after the preceding document is a subsequent document, the control section performs a skew judgment, based on an image of the preceding document scanned by the reading section, which determines whether the side edge portion of the preceding document is displaced into a nip region sandwiched between the feed roller and the separation section, and determines a transport error when the side edge portion of the preceding document is determined to be displaced into the nip region and also the detection section detects the subsequent document.

A control method of the reading device that solves the above problem, the recording device including a placement section on which a plurality of document is placed, a feed roller that feeds the document from the placement section, a separation section that separates the document being fed by the feed roller, a reading section that scans the document being transported in a transport direction, and a detection section that detects the document that is placed on the placement section, the control method of the reading device includes, when assuming that a document fed first is a preceding document and that a document fed after the preceding document is a subsequent document, determining, based on an image of a preceding document scanned by the reading section, whether a side edge portion of the preceding document is displaced into a nip region sandwiched by the feed roller and the separation section and determining a transport error when the control section determines that the side edge portion of the preceding document is displaced into the nip region and also the detection section detects the subsequent document.

Hereinafter, an embodiment of a reading device and a control method of the reading device will be described below with reference to figures. The reading device is, for example, a sheet-feed scanner in which a fixed reading section scans a document, such as paper-sheet or a film, being transported.

As shown in <FIG>, the reading device <NUM> may be equipped with a housing <NUM> and a support section <NUM>. The support section <NUM> supports the housing <NUM>. The support section <NUM> is attached to the housing <NUM>. The support section <NUM> is placed, for example, on a horizontal surface.

The housing <NUM> has two openings: a supply port <NUM> and a discharge port <NUM>. The supply port <NUM> is an opening through which a document M is fed. Through the supply port <NUM>, the document M is fed into the housing <NUM>. The discharge port <NUM> is an opening through which the document M is discharged. The document M is discharged from the housing <NUM> through the discharge port <NUM>.

The reading device <NUM> may be equipped with a transport path <NUM>. The transport path <NUM> is the path along which the document M is transported. The transport path <NUM> extends through the housing <NUM>. The transport path <NUM> extends from the supply port <NUM> toward the discharge port <NUM>. The transport path <NUM> extends in the transport direction D1.

The reading device <NUM> may be equipped with a discharge tray <NUM>. The discharge tray <NUM> is attached to the housing <NUM>. The discharge tray <NUM> can pivot with respect to the housing <NUM>, for example. The discharge tray <NUM> can be opened against the housing <NUM> to receive a document M. The discharge tray <NUM> receives the scanned document M. The discharge tray <NUM> receives the document M discharged from the discharge port <NUM>.

The reading device <NUM> is equipped with a placement section <NUM>, a detection section <NUM>, a feed section <NUM>, and a reading section <NUM>. The placement section <NUM> is attached to the housing <NUM>. A plurality of documents M can be placed on the placement section <NUM>. "Placement" means to put something on the surface of it. A document M, which has not yet been scanned, is set on the placement section <NUM>. The document M is set on the placement section <NUM> with a tip end Ef of the document M entering the supply port <NUM>. When the document M is set on the placement section <NUM>, the tip end Ef of the document M hits the feed section <NUM>.

The detection section <NUM> detects the document M placed on the placement section <NUM>. The detection section <NUM> may be, for example, a contact sensor with a lever, or a non-contact sensor such as an optical sensor.

The feed section <NUM> has a feed roller <NUM> and a separation section <NUM>. The documents M placed on the placement section <NUM> are fed one by one in turn into the transport path <NUM> by the feed section <NUM>. In this embodiment, any two of the multiple documents M that are fed consecutively are also referred to as a preceding document M1 and a subsequent document M2. The preceding document M1 is the document M that is fed first. Subsequent document M2 is the document M that is fed following the preceding document M1. If no distinction is made between the preceding document M1 and the subsequent document M2, the document is simply referred to as document M.

The feed roller <NUM> feeds the document M from the placement section <NUM>. The feed roller <NUM> is driven and rotated. The feed roller <NUM> may be located at a position above the separation section <NUM>. The feed roller <NUM> may be in contact with a front surface of the document M.

The separation section <NUM> separates the document M fed by the feed roller <NUM>. The separation section <NUM> in this embodiment is a roller that separates the document M to one sheet at a time. The separation section <NUM> may contact the back surface of the document M.

The separation section <NUM> is composed of rollers that have a higher coefficient of friction against the document M than a coefficient of friction between the documents M, for example. The separation section <NUM> is subjected to a rotational load, for example, by a torque limiter. Therefore, in a case where the feed roller <NUM> and the separation section <NUM> sandwich multiple documents M, when the feed roller <NUM> drives and rotates, the separation section <NUM> is less likely to be driven and rotated. That is, the documents M are separated into single sheets by the feed roller <NUM> and the separation section <NUM>. By this, the possibility of two overlapping documents M being transported is reduced.

As shown in <FIG>, the feed roller <NUM> and the separation section <NUM> may be located in the transport path <NUM> in the center of the scanning direction D2. In this embodiment, the center of the transport path <NUM> in the scanning direction D2 is indicated by a virtual center line C. The scanning direction D2 is a direction that intersects the transport direction D1. The scanning direction D2 is a width direction of the document M and is also an axial direction of the feed roller <NUM>. The feed roller <NUM> and the separation section <NUM> sandwich the document M in a nip region A, shown in <FIG> as a single dotted line.

The nip region A is a region between the feed roller <NUM> and the separation section <NUM> in the vertical direction D3, which is perpendicular to the transport path <NUM>. The nip region A is the region where the feed roller <NUM> and the separation section <NUM> contact each other in a state where there is no document M between the feed roller <NUM> and the separation section <NUM>. The portion of the document M located in nip region A is sandwiched between the feed roller <NUM> and the separation section <NUM>. The size of the nip region A in the scanning direction D2 may be the same as the smaller one of the feed roller <NUM> and the separation section <NUM>. When the separation section <NUM> is smaller than the feed roller <NUM>, the nip region A is from one end portion of the separation section <NUM> to the other end portion of the separation section in the scanning direction D2. The size of the nip region A in the scanning direction D2 is smaller than the smallest size document M that can be scanned by the reading device <NUM>. The nip region A may be in the range in the scanning direction D2 of nip distance Ln from the virtual center line C.

As shown in <FIG>, the reading device <NUM> may be equipped with a rear end detection section <NUM>. The reading device <NUM> may be equipped with a plurality of rear end detection sections <NUM> provided side by side in the scanning direction D2. The rear end detection section <NUM> may be a sensor that detects the document M. The rear end detection section <NUM> detects a rear end Eb of the document M. The rear end detection section <NUM> may detect the tip end Ef of the document M. The rear end detection section <NUM> is, for example, an optical sensor. The rear end detection section <NUM> is provided, for example, between the feed roller <NUM> and the reading section <NUM> in the transport direction D1.

The reading device <NUM> may be equipped with a transport section <NUM>. The transport section <NUM> is configured to transport the document M. The transport section <NUM> transports the document M along the transport path <NUM>. The transport section <NUM> includes, for example, one or more rollers. The transport section <NUM> includes, for example, a first roller pair <NUM> and a second roller pair <NUM>.

The first roller pair <NUM> and the second roller pair <NUM> are provided further downstream than is the feed section <NUM> in the transport direction D1. The first roller pair <NUM> and the second roller pair <NUM> are arranged, for example, along the transport path <NUM>. The feed section <NUM>, the first roller pair <NUM>, and the second roller pair <NUM> in this embodiment are arranged in this order in the transport direction D1. The first and second roller pairs <NUM> and <NUM> transport the document M by the rollers of the first and second roller pairs <NUM> and <NUM> rotating in the state of sandwiching the document M.

The first roller pair <NUM> is located further upstream than is the reading section <NUM> in the transport direction D1. The second roller pair <NUM> is located further downstream than is the reading section <NUM> in the transport direction D1. The first roller pair <NUM> and the second roller pair <NUM> are located in the transport direction D1, sandwiching the reading section <NUM>.

The reading device <NUM> may be equipped with a rotation detection section <NUM> that detects the rotation of the first roller pair <NUM>. The rotation detection section <NUM> is, for example, a rotary encoder. The rotation detection section <NUM> may output the amount of rotation of the first roller pair <NUM> by detecting a scale on the encoder scale rotating with the first roller pair <NUM>.

The reading device <NUM> may have one or more reading sections <NUM>. The reading section <NUM> is configured to scan the document M. The reading section <NUM> scans the document M that is transported in the transport direction D1. The reading section <NUM> is accommodated in the housing <NUM>.

The reading device <NUM> in this embodiment has two reading sections <NUM>. The two reading sections <NUM> are located so as to sandwich the transport path <NUM>. The two reading sections <NUM> are located between the first roller pair <NUM> and the second roller pair <NUM> in the transport path <NUM>. The two reading sections <NUM> face each other. The reading section <NUM> is elongated in the scanning direction D2. If the scanning direction D2 is referred to as the main scanning direction, the transport direction D1 can be said to be the sub-scanning direction.

The two reading sections <NUM> scan different surfaces of the document M. One of the two reading sections <NUM> scans the front surface of the document M. The other of the two reading sections <NUM> scans the back surface of the document M. By this, the reading device <NUM> scans one side of the document M, or both sides of the document M.

The reading section <NUM> has, for example, a light source <NUM>, a plurality of image sensors <NUM>, and a background plate <NUM>. The light source <NUM> is, for example, an LED or a fluorescent lamp. The light source <NUM> emits light toward the facing reading section <NUM>. The light source <NUM> is, for example, elongated in the scanning direction D2.

The plurality of image sensors <NUM> are arranged in the scanning direction D2. The plurality of image sensors <NUM> are in a modular configuration. The image sensor <NUM> is, for example, a contact image sensor. Specifically, the image sensor <NUM> is a CMOS image sensor. The image sensor <NUM> converts a received light into a photoelectric signal. The image sensor <NUM> outputs an output value corresponding to the amount of received light.

The image sensor <NUM> may be a monochrome sensor or a color sensor. The reading section <NUM> may be configured to scan the document M in full color. For example, the reading section <NUM> may be configured to read the document M in the three colors of RGB. The reading section <NUM> may be configured to read the document M in gray scale.

The background plate <NUM>, for example, faces the image sensor <NUM> and the light source <NUM> of the other reading section <NUM>. The background plate <NUM> is irradiated with light from the light source <NUM> of the facing reading section <NUM>. The background plate <NUM> reflects the irradiated light. The light reflected by the background plate <NUM> enters the image sensor <NUM> of the reading section <NUM> facing the background plate <NUM>. The background plate <NUM> is scanned as a background together with the document M by the image sensor <NUM>.

When the image sensor <NUM> scans the background plate <NUM> along with the document M, the background plate <NUM> desirably presents a color that enables distinguishing between the document M and the background plate <NUM>. The background plate <NUM>, for example, is a gray color.

The reading device <NUM> may be equipped with an operation section <NUM>. The operation section <NUM> is attached to, for example, the housing <NUM>. The operation section <NUM> is, for example, a touch panel. The operation section <NUM> accepts operations from the user. The operation section <NUM> is not limited to a touch panel, and may be, for example, buttons, switches, or the like.

The reading device <NUM> may be configured, for example, to accept operations from a terminal device that is communicatively connected to the reading device <NUM>. The terminal device is, for example, a personal computer or a smartphone owned by the user.

The reading device <NUM> is equipped with a control section <NUM>. The control section <NUM> comprehensively controls the drive mechanisms in the reading section <NUM> and controls the various operations performed by the reading section <NUM>. The control section <NUM> can be configured as a circuit that includes α: one or more processors that execute various processes according to a computer program, β: one or more dedicated hardware circuits that execute at least some of the various processes, or γ: a combination thereof. The hardware circuit is, for example, an application specific integrated circuit. The processor includes a CPU and a memory such as a RAM and a ROM. The memory stores program code or instructions configured to cause the CPU to perform processing. The memory, that is, the computer-readable medium, includes any readable medium that can be accessed by a general purpose or dedicated computer.

As shown in <FIG>, the control section <NUM> obtains an image <NUM> of the tip end region of the preceding document M1 scanned by the reading section <NUM>. In other words, the control section <NUM> obtains an image of the preceding document M1 scanned by the reading section <NUM>. The control section <NUM> obtains data of the image <NUM> from the signal that is output from the reading section <NUM>. The image <NUM> of the tip region includes the tip end Ef. The size of the image <NUM> of the tip end region in the transport direction D1 is smaller than that of the preceding document M1. In other words, the image <NUM> of the tip end region does not include the rear end Eb of the preceding document M1.

The image <NUM> includes a document region <NUM> and a background region <NUM>. The document region <NUM> is a region where pixels are generated by scanning of the document M. The background region <NUM> is a region where pixels are generated by scanning of the background plate <NUM>.

The control section <NUM> detects the document region <NUM> from the image <NUM>. For example, the control section <NUM> detects the document region <NUM> by considering pixels that show luminance values included in a background range as the background region <NUM>.

The control section <NUM> may calculate a tilt angle θ from the image <NUM>. The tilt angle θ is the angle of the preceding document M1 with respect to the scanning direction D2. The tilt angle θ is an angle between the tip end Ef of the preceding document M1 and the scanning direction D2.

The control section <NUM> may calculate the right tip end distance Lr or the left tip end distance Ll from the image <NUM>. Each of the right tip end distance Lr and the left tip end distance Ll is an example of a tip end distance. The right tip end distance Lr is the distance in the scanning direction D2 from the right side edge portion Er of the preceding document M1 to the nip region A. The left tip end distance Ll is a distance in the scanning direction D2 from the left side edge portion El of the preceding document M1 to the nip region A.

Each of the right side edge portion Er and the left side edge portion El is an example of a side edge portion. The right side edge portion Er is the side edge portion located on the right side of the document M as viewed in the transport direction D1 of the document M. The left side edge portion El is a side edge portion located on the left side of the document M as viewed in the transport direction D1 of the document M. When the downstream side corners of the document M in the transport direction D1 are viewed in transport direction D1, the right side corner is also referred to as a right tip corner Cr, and the left side corner is also referred to as a left tip corner Cl.

As shown in <FIG>, when the document M is skewed to a position where the right tip corner Cr is located further downstream than is the left tip corner Cl in the transport direction D1, this is also referred to as "proceeding right-side first. " In contrast, when the document M is skewed to a position where the left tip corner Cl is located further downstream than is the right tip corner Cr in the transport direction D1, this is also referred to as "proceeding left-side first.

In the case of preceding right-side first, the control section <NUM> calculates the left tip end distance Ll as the tip end distance. The left tip end distance Ll is the difference between the distance in the scanning direction D2 from the left side edge portion El to the virtual center line C and the nip distance Ln, at the downstream end of the image <NUM>.

In the case of proceeding left-side first, the control section <NUM> calculates the right tip end distance Lr as the tip end distance. The right tip end distance Lr is the difference between the distance in the scanning direction D2 from the right side edge portion Er to the virtual center line C and the nip distance Ln, at the downstream end of the image <NUM>.

The control section <NUM> may obtain the width W of the preceding document M1 from the image <NUM>. The width W is the length from the right side edge portion Er to the left side edge portion El and parallel to the tip end Ef. The width W is also the length of the tip end Ef.

The control section <NUM> may calculate a preceding length Lf from the image <NUM>. The preceding length Lf is a length along the virtual center line C from the tip end Ef to the downstream end of the image <NUM>. As shown in <FIG>, the control section <NUM> may calculate an allowable distance Lt. For example, the control section <NUM> calculates the allowable distance Lt based on the following formula: <MAT>.

The tilt amount of the document M may change as it is transported. The correction value B is a value to compensate for the tilt amount that changes during transportation. Especially, a document M with a long length in the transport direction D1 tends to have a large difference between the tilt angle θ, which is formed by the scanning direction D2 and the tip end Ef, and the angle formed by the scanning direction D2 and the rear end Eb. Thus, the control section <NUM> corrects the tilt angle θ using an amount by which the tilt of the preceding document M1 is estimated to change during transportation. The control section <NUM> may correct the tip end distance using an amount by which the tilt of the preceding document M1 is estimated to change during transportation.

The control section <NUM> may obtain the document length Lm. The document length Lm is a length in the transport direction D1 from the tip end Ef to the rear end Eb. The control section <NUM> may obtain the document length Lm by using the image <NUM> and the detection result of the rear end detection section <NUM>. The control section <NUM> may obtain the document length Lm based on the detection result of the rotation detection section <NUM>. For example, the control section <NUM> may obtain from the rotation detection section <NUM> the distance that the preceding document M1 was transported from the time the image <NUM> was scanned to the time the rear end detection section <NUM> detects the rear end Eb, and then obtain the document length Lm by adding the distance from the reading section <NUM> to the rear end detection section <NUM> to the preceding length Lf.

A control method of the reading device <NUM> will be described with reference to a flowchart shown in <FIG>. The decision routine shown in <FIG> is executed at the timing when the reading section <NUM> has scanned the image <NUM> of the tip end region of the preceding document M1.

As shown in <FIG>, in step S101, the control section <NUM> calculates the tilt angle θ from the image <NUM>. In step S102, the control section <NUM> calculates the width W of the preceding document M1 from the image <NUM>.

In step S103, the control section <NUM> compares the width W of the preceding document M1 with a width threshold value, which is an example of a threshold value. The width threshold value may be a preset value for the document M to be extracted. For example, when a receipt, an example of a document M, is to be extracted, the width threshold value may be set to <NUM>.

If the width W is less than or equal to the width threshold vale, step S103 becomes YES, and the control section <NUM> advances the process to step S106. If the width W is greater than the width threshold value, step S103 becomes NO, and the control section <NUM> advances the process to step S104. In step S104, the control section <NUM> compares the tilt angle θ with a tilt threshold value. The tilt threshold value may be a preset value, or it may be a value set according to the width W.

If the tilt angle θ is equal to or greater than the tilt threshold value, step S104 becomes YES, and the control section <NUM> advances the process to step <NUM>. In step S105, the control section <NUM> determines a transport error and ends the process. If the tilt angle θ is smaller than the tilt threshold value, the step S104 becomes NO, and the control section <NUM> ends the process.

In step S106, the control section <NUM> determines whether the preceding document M1 is proceeding right-side first. If the preceding document M1 is proceeding right-side first, step S106 becomes YES, and the control section <NUM> advances the process to step S107. In step S107, the control section <NUM> calculates the left tip end distance Ll.

If the preceding document M1 is proceeding left-side first, step S106 becomes NO, and the control section <NUM> advances the process to step S108. In step S108, the control section <NUM> calculates the right tip end distance Lr.

In step S109, the control section <NUM> calculates the preceding length Lf from the image <NUM>. In step S110, the control section <NUM> calculates the allowable distance Lt. In step S111, the control section <NUM> determines whether the rear end detection section <NUM> has detected the rear end Eb of the preceding document M1. If the rear end detection section <NUM> has not detected the rear end Eb, step S111 becomes NO, and the control section <NUM> advances the process to step S112.

In step S112, the control section <NUM> determines whether the transport distance that the preceding document M1 was transported after the image <NUM> was scanned is equal to or greater than the allowable distance Lt. If the transport distance is equal to or greater than the allowable distance Lt, step S112 becomes YES, and the control section <NUM> advances the process to step S113. In step S113, the control section <NUM> determines a transport error and ends the process. If the transport distance is less than the allowable distance Lt, step S112 becomes NO, and the control section <NUM> advances the process to step S111.

If the rear end detection section <NUM> detects the rear end Eb of the preceding document M1, step S111 becomes YES, and the control section <NUM> advances the process to step S114. In step S114, the control section <NUM> calculates the document length Lm.

In step S115, the control section <NUM> compares the difference between the document length Lm and the preceding length Lf with the allowable distance Lt. If the allowable distance Lt is longer than the difference between the document length Lm and the preceding length Lf, step S115 becomes NO, and the control section <NUM> ends the process. If the allowable distance Lt is equal to or less than the difference between the document length Lm and the preceding length Lf, step S115 becomes YES, and the control section <NUM> advances the process to step S116.

In step S116, the control section <NUM> determines whether there is a subsequent document M2. That is, if the detection section <NUM> does not detect a document M placed on the placement section <NUM>, the control section <NUM> determines that there is no subsequent document M2. If there is no subsequent document M2, step S116 becomes NO, and the control section <NUM> ends the process.

If the detection section <NUM> detects a document M placed on the placement section <NUM>, the control section <NUM> determines that there is a subsequent document M2. If there is a subsequent document M2, step S116 becomes YES, and the control section <NUM> advances the process to step S117. In step S117, the control section <NUM> determines a transport error and ends the process.

The operations of this embodiment will be described. The control section <NUM> determines whether the right side edge portion Er or the left side edge portion El of the preceding document M1 is displaced into the nip region A, based on the image <NUM>. This determination is also referred to as a skew judgment. Specifically, the control section <NUM> performs the skew judgment based on the tilt angle θ and the tip end distance. The control section <NUM> calculates the allowable distance Lt based on the tilt angle θ and the tip end distance.

The control section <NUM> may perform the skew judgment based on the document length Lm. If the allowable distance Lt is equal to or less than the difference between the document length Lm and the preceding length Lf, the control section <NUM> determines that the right side edge portion Er or the left side edge portion El is displaced into the nip region A. If the allowable distance Lt is longer than the difference between the document length Lm and the preceding length Lf, the control section <NUM> determines that the right side edge portion Er and the left side edge portion El are not displaced into the nip region A.

If the transport distance that the preceding document M1 was transported after the image <NUM> was scanned is equal to or greater than the allowable distance Lt, the control section <NUM> determines that the right side edge portion Er or the left side edge portion El is displaced into the nip region A. If the transport distance is less than the allowable distance Lt, the control section <NUM> determines that the right side edge portion Er and the left side edge portion El are not displaced into the nip region A. When the control section <NUM> determines that the right side edge portion Er and the left side edge portion El are not displaced into the nip region A, the control section <NUM> feeds the subsequent document M2.

The control section <NUM> may perform the skew judgment before the rear end detection section <NUM> detects the rear end Eb of the preceding document M1. In other words, the control section <NUM> may perform the skew judgment in step S112 before the rear end Eb is detected in the determination routine of step S111.

The control section <NUM> may perform the skew judgment at the timing when the rear end detection section <NUM> detects the rear end Eb of the preceding document M1. In other words, the control section <NUM> may perform the skew judgment in step S115 when the rear end Eb is detected in the determination routine of step S111.

If the control section <NUM> determines that the width W of the preceding document M1 is equal to or less than the width threshold value, the control section <NUM> may perform the skew judgment. In other words, the control section <NUM> may perform the skew judgment in step S112 or step S115 if the width W is less than the width threshold value in the determination routine of step S103.

The control section <NUM> determines a transport error of the document M. Specifically, the control section <NUM> determines a transport error when the control section <NUM> determines that the right side edge portion Er or the left side edge portion El of the preceding document M1 is displaced into the nip region A and also the detection section <NUM> detects the subsequent document M2.

If the control section <NUM> determines a transport error, the control section <NUM> may stop the drive of the feed section <NUM> and transport section <NUM>. If the control section <NUM> determines that the right side edge portion Er or the left side edge portion El of the preceding document M1 is displaced into the nip region A but does not detect the subsequent document M2, the control section <NUM> may discharge the preceding document M1 to the discharge tray <NUM>. Effects of embodiment.

Effects of this embodiment will be described.

This embodiment can be modified as follows. This embodiment and the following modifications can be implemented in combination with each other within a range that is not technically contradictory.

The phrase "at least one" as used in this specification means "one or more" of the desired options. As an example, if the number of options is two, the phrase "at least one" as used in this specification means "only one option" or "both of the two options". As another example, if the number of options is three or more, the phrase "at least one" as used in this specification means "only one option" or "any combination of two or more options".

Hereinafter, technical ideas grasped from the above-described embodiment and modifications, and operations and effects thereof, will be described.

Claim 1:
A reading device, comprising:
a placement section on which a plurality of documents is placed;
a feed roller that feeds the documents from the placement section;
a separation section that separates the documents being fed by the feed roller;
a reading section that scans the documents being transported in a transport direction;
a control section that determines a transport error of the documents; and
a detection section that detects the documents that are placed on the placement section; wherein
when assuming that a document fed first is a preceding document and that a document fed after the preceding document is a subsequent document,
characterized in that:
the control section
performs a skew judgment based on an image of the preceding document scanned by the reading section, the skew judgment determining whether a side edge portion of the preceding document is displaced into a nip region sandwiched between the feed roller and the separation section and
determines a transport error when the side edge portion of the preceding document is determined to be displaced into the nip region and also the detection section detects the subsequent document.