Patent ID: 12192425

DESCRIPTION OF EMBODIMENTS

The present disclosure will be described briefly.

In order to solve the above-described problem, an image reading device, according to the first embodiment of the present disclosure, includes a motor, a reading section that reads an image on a medium, a first transporting roller that transports the medium in a transport direction by driving force of the motor and that is provided upstream of the reading section in the transport direction, a second transporting roller that transports the medium in the transport direction by driving force of the motor and that is provided downstream of the reading section in the transport direction, and a measuring section configured to measure, using an encoder sensor, the rotational position of an encoder scale, wherein the encoder scale is provided on a rotation shaft of the second transporting roller.

According to the present aspect, the encoder scale is provided on the rotation shaft of the second transporting roller. Accordingly, even if there is a disturbance in the movement amount of the medium due to an instantaneous change in state when the rear end of the medium separates from the first transporting roller and changes to a transport state using only the second transporting roller, it is possible to detect information regarding the disturbance using the encoder scale. As a result, it is possible to reduce degradation of image quality.

In addition, by locating the encoder scale on the rotation shaft of the second transporting roller, the space efficiency is increased, which leads to the miniaturization of the apparatus.

A image reading device according to a second aspect of the present disclosure is an aspect according to the first aspect, wherein the first transporting roller has an upper first transporting roller and a lower first transporting roller that nips the medium with the upper first transporting roller at a first nip position and transports the medium, and the second transporting roller has an upper second transporting roller and a lower second transporting roller that nips the medium at a second nip position with the upper second transporting roller and transports the medium, the motor transmits driving force to rotation shafts of the upper first transporting roller, the lower first transporting roller, the upper second transporting roller, and the lower second transporting roller, a length of the apparatus in a depth direction at a position where the second transporting roller is provided is longer than a length of the apparatus in the depth direction at a position where the first transporting roller is provided, and the encoder scale is provided on a rotation shaft of the lower second transporting roller.

According to the present aspect, since the driving force is transmitted to the four rollers of the upper first transporting roller, the lower first transporting roller, the upper second transporting roller, and the lower second transporting roller, it is possible to measure the movement distance of the medium in a state where the transporting force is improved. As a result, slippage of the roller is suppressed, so that the measurement accuracy of the movement distance of the medium is improved.

In addition, since the encoder scale is provided on the rotation shaft of the lower second transporting roller having the largest depth margin among the four rollers, the space use efficiency is improved.

A image reading device according to a third aspect is an aspect according to the second aspect of the present disclosure, wherein driving force of the motor is transmitted to the lower first transporting roller and to the upper second transporting roller via the rotation shaft of the lower second transporting roller and is transmitted to the upper first transporting roller via the rotation shaft of the upper second transporting roller and the encoder scale is provided on the rotation shaft of the lower second transporting roller to which the driving force from the motor is transmitted first.

According to the present aspect, since the measuring section is disposed on the rotation shaft of the lower second transporting roller which is a driving shaft to which the driving force from the motor reaches first, the measurement accuracy of the movement distance of the medium is improved.

An image reading device according to a fourth aspect of the present disclosure is an aspect according to the second aspect or the third aspect, further including a universal joint provided on the rotation shaft of the upper second transporting roller, wherein the upper second transporting roller and the lower second transporting roller are provided between the universal joint and the encoder scale in a rotation shaft direction.

According to the present aspect, the upper second transporting roller and the lower second transporting roller are provided between the universal joint and the encoder scale in the rotation shaft direction. That is, since the universal joint and the encoder scale are provided on the opposite sides in the direction of the rotation shaft, the size of the apparatus can be reduced.

An image reading device according to a fifth aspect of the disclosure is an aspect according to the first aspect, wherein the second transporting roller includes a drive roller rotated by the motor, and a driven roller driven to rotate by the drive roller, the encoder scale is disposed on a rotation shaft of the drive roller.

According to the present aspect, since the encoder scale is disposed on the rotation shaft of the drive roller, it is possible to measure the movement distance of the medium.

An image reading device according to a sixth aspect of the disclosure is an aspect according to the first aspect, wherein the second transporting roller has a drive roller rotated by the motor and a driven roller configured to rotate together with the drive roller, and the encoder scale is disposed on a rotation shaft of the driven roller.

According to the present aspect, since the encoder scale is disposed on the rotation shaft of the driven roller, it is possible to more accurately measure the movement distance of the medium.

An image reading device according to a seventh aspect of the disclosure is an aspect according to any one of the first to sixth aspects, further including a medium detection section provided upstream of the reading section and a control section, wherein the control section measures, using the measuring section, current distance of after the medium passes through the medium detection section, calculates a differential distance between the current distance and a target distance stored in advance, specifies a position where the difference distance exists in the image data read by the reading section, and executes image correction on the specified position.

According to the present aspect, the control section specifies a position where the differential distance is present in the image data read by the reading section, and executes image correction on the specified position. By this image correction, it is possible to reduce the influence of the disturbance of the image, thereby reducing the deterioration of the image quality.

According to an eighth aspect of the present disclosure, the image reading device, according to any one of the fifth to seventh aspect of the present invention, wherein the first transporting roller has an upper first transporting roller and a lower first transporting roller that nips the medium with the upper first transporting roller at a first nip position and transports the medium, the second transporting roller has an upper second transporting roller and a lower second transporting roller that nips the medium with the upper second transporting roller at a second nip position and transports the medium, and the image correction is executed based on measurement information measured by the measuring section during a period from when a rear end of the medium passes through the first nip position to when the rear end of the medium passes through the second nip position.

According to this aspect, the image correction is executed based on the measurement information measured by the measuring section during a period from when the rear end of the medium passes through the first nip position to when the rear end of the medium passes through the second nip position. As a result, even if there is a disturbance in the movement amount of the medium due to an instantaneous change in state when the trailing end of the medium passes through the first nip position and changes to a cantilevered transport state due to only the second nip position, since the disturbance is detected and the image correction is executed, it is possible to reduce a decrease in image quality.

An image reading device according to a ninth aspect of the present disclosure is an aspect according to the first aspect, further including a third transporting roller that transports the medium in a transporting direction and that is provided downstream of the second transporting roller in the transporting direction, a first transporting path through which the medium is transported, the first transporting path including a portion from a nip position of the first transporting roller to a nip position of the second transporting roller, a second transporting path through which the medium is transported, the second transporting path including a portion from the nip position of the second transporting roller to a nip position of the third transporting roller, and a control section that controls transporting of the medium, wherein the motor has a DC motor, the first transporting path includes a straight path, the second transporting path includes a curved path, the control section stops transporting of the medium when a load of the DC motor exceeds a threshold value, and the threshold value when the medium is transported along the second transporting path is larger than the threshold value when the medium is transported along the first transporting path.

In this specification, the “straight path” does not need to be strictly a straight line, but includes a path that can be regarded as a substantially straight line.

According to the present aspect, in the control section, the threshold value in a case where the medium is transported on the second transporting path is larger than the threshold value in a case where the medium is transported on the first transporting path. That is, since a plurality of threshold values of the transporting load is provided, when the transportation of the medium is to be stopped, the transportation of the medium can be stopped earlier than in the prior art, thereby suppressing damage to the medium.

An image reading device according to a tenth aspect of the disclosure is an aspect according to the ninth aspect, further including a plurality of medium detection sections configured to detect that the medium has passed by each of the first transporting roller and the second transporting roller, wherein the control section executes based on a combination of the detection information from the plurality of the medium detection sections to increase the threshold as the number of detections increases, and to decrease the threshold as the number of detections decreases.

According to the aspect, the control section increases the threshold value when the number of detections increases, and decreases the threshold value when the number of detections decreases, based on the combination of the detection information of the plurality of medium detection sections. Accordingly, since a plurality of appropriate threshold values can be used, the transporting medium can be stopped earlier than in the case of using a fixed threshold value, and damage to the medium can be suppressed.

An image reading device according to an eleventh aspect of the present disclosure is an aspect according to the tenth aspect, wherein the control section uses the first threshold value in the first curved path having the first curvature and uses the second threshold value larger than the first threshold value in the second curved path having the second curvature larger than the first curvature.

According to the present aspect, the control section uses the first threshold value in the first curved path having the first curvature, and uses the second threshold value larger than the first threshold value in the second curved path having the second curvature larger than the first curvature. Accordingly, since it is possible to use a plurality of appropriate threshold values, it is possible to stop the transportation of the medium at an early stage and to suppress damage to the medium compared to a case where a fixed threshold value is used.

An image reading device according to a twelfth aspect of the disclosure is an aspect according to the tenth aspect, wherein the third transporting roller includes a lower third transporting roller that is driven by the motor and that transports the medium, and an upper third transporting roller that is driven to rotate by the lower third transporting roller and that transports the medium while nipping the medium with the lower third transporting roller at a third nip position, and the threshold value when the medium is transported by the first transporting roller or the second transporting roller may be larger than the threshold value when the medium is transported by only the third transporting roller.

According to the present aspect, the threshold value in a case where the medium is transported by the first transporting roller or the second transporting roller is larger than the threshold value in a case where the medium is transported only by the third transporting roller. Accordingly, since it is possible to use a plurality of appropriate threshold values according to the transporting load, it is possible to stop the transportation of the medium at an early stage and to suppress damage to the medium compared to a case where a fixed threshold value is used.

An image reading device according to a thirteenth aspect of the present disclosure is an aspect according to the ninth aspect, wherein the first transporting path and the second transporting path overlap with a portion of the encoder scale in the side viewing direction.

According to the present aspect, the first transporting path and the second transporting path are disposed so as to overlap with a portion of the encoder scale in the side viewing direction. That is, by disposing the encoder scale in the first transporting path and the second transporting path, the space efficiency is increased, which leads to the miniaturization of the apparatus.

According to a fourteenth aspect, an image correction method of an image reading device, the image reading device having a motor, a reading section configured to read an image on a medium, a first transporting roller that transports the medium in a transport direction by driving force of the motor and that is provided upstream of the reading section in the transport direction, a second transporting roller that transports the medium in the transport direction by driving force of the motor and that is provided downstream of the reading section in the transport direction, and a measuring section configured to measure, using an encoder sensor, the rotational position of an encoder scale, wherein the encoder scale is mounted on a rotation shaft of the second transporting roller and a medium detection section is provided upstream of the reading section, the image correction method includes measuring, using the measuring section, a current distance of after the medium passes through the medium detection section by the control section performing, calculating a differential distance between the current distance and a target distance stored in advance, specifying a position where a difference distance exists in the image data read by the reading section, and executing an image correction on the specified position by the control section.

According to the present aspect, the same effect as that of the seventh aspect can be obtained.

An image correction method of an image reading device according to a fifteenth aspect of the present disclosure is an aspect according to a fourteenth aspect, the image reading device has a third transporting roller that transports the medium in a transporting direction and that is provided downstream of the second transporting roller in the transporting direction, a first transporting path through which the medium is transported, the first transporting path having a portion from a nip position of the first transporting roller to a nip position of the second transporting roller, a second transporting path through which the medium is transported, the second transporting path having a portion from the nip position of the second transporting roller to a nip position of the third transporting roller, and the control section that control to transport the medium, wherein the motor includes a DC motor, the first transporting path includes a straight path, and the second transporting path includes a curved path, the control section controls stopping transportation of the medium when a load of the DC motor exceeds a threshold value, and executing a threshold value in a case where the medium is transported on the second transporting path is set to be larger than a threshold value in a case where the medium is transported on the first transporting path, using the control section.

According to the present aspect, the same effect as that of the ninth aspect can be obtained.

First Embodiment

An image reading device according to a first embodiment of the present disclosure will be described below in detail with reference toFIGS.1to5.

In the following description, three axes orthogonal to each other are referred to as an X-axis, a Y-axis, and a Z-axis, respectively, as shown in theFIGS.1to6. The direction indicated by the arrows of the three axes (X, Y, Z) is the “+” direction of each direction, and the opposite direction is the “−” direction. The Z axis direction corresponds to a vertical direction, that is, a direction in which gravity acts, a +Z direction indicates a vertically upward direction, and a −Z direction indicates a vertically downward direction. The X axis direction and the Y axis direction correspond to horizontal directions. The +Y direction indicates the front direction of the apparatus, and the −Y direction indicates the rear direction of the apparatus. The +X direction indicates the right direction of the apparatus, and the −X direction indicates the left direction of the apparatus.

The image reading device according to the present embodiment is a scanner capable of reading an image on a medium. Here, image means what is visually recorded on the medium, and is, for example, a character, a figure, a table, a picture, a photograph, or the like. The medium is not limited to a sheet, and may be a card, a booklet, or the like.

As illustrated inFIGS.1to4, an image reading device1includes a motor3, a reading section7that reads an image of a medium5, a first transporting roller9that transports the medium5in a transport direction F along a transporting path21by a driving force of the motor3and that is provided upstream of the reading section7in the transport direction F, and a second transporting roller11that transports the medium5in the transport direction F by a driving force of the motor3and that is provided downstream of the reading section7in the transport direction F.

Further, a measuring section17for measuring the rotational position of an encoder scale13with an encoder sensor15is provided. The encoder scale13is provided on a rotation shaft19of the second transporting roller11.

As shown inFIG.3, the driving force of the motor3is transmitted from a belt2to a gear6, and further to a gear8via a belt4from a gear which is a small-diameter gear attached to a shaft10of the gear6, but which cannot be seen in the drawing because it is hidden behind the gear6. Since the gear8is integrally attached to the rotation shaft19, the driving force of the motor3is transmitted to the rotation shaft19to rotate, thereby rotating the second transporting roller11.

As illustrated inFIGS.1and2, a feed roller14, which feeds the medium5set in a medium support section12(FIG.1) in the transport direction F toward the first transporting roller9, is disposed upstream of the first transporting roller9in the transport direction F. Reference numeral16denotes a transporting inlet of the medium5.

In the present embodiment, a reversing section18, which forms a portion of the transporting path21, is provided downstream of the second transporting roller11in the transport direction F. An intermediate roller20is disposed at a downstream end portion of the reversing section18, and a discharge roller22is disposed further downstream thereof. The medium5discharged through the discharge roller22is supported and held by a receiving plate26of a discharge receiving section24(FIG.1).

As shown inFIG.1, the medium support section12is provided with an extension support section28. The extension support section28is located on the back side of a medium support plate30of the medium support section12and substantially at the center in the width direction (X axis direction), and is formed of a substantially plate-shaped member that is long and narrow as a whole. The extension support section28has a first extension section32which is displaceable between a stored state (not shown) in which the extension support section28is stored in the medium support section12and a developed state (state ofFIG.1) in which the extension support section28is developed by being rotated with respect to the medium support section12and supports the medium5together with the medium support section12.

Furthermore, the extension support section28has a second extension section34which is displaceable into a stored state (not shown) in which the extension support section28is stored in the first extension section32and a developed state (the state ofFIG.1) in which the extension support section28slides and extends from the first extension section32and supports the medium5together with the first extension section32.

In the present embodiment, each of the first transporting roller9and the second transporting roller11is constituted by a nip roller pair that nips and transports the medium5. Specifically, the first transporting roller9includes an upper first transporting roller23and a lower first transporting roller27that transports the medium5by nipping the medium5with the first transporting roller23at a first nip position25. The second transporting roller11includes an upper second transporting roller29and a lower second transporting roller33that nips the medium5with the upper second transporting roller29at a second nip position31and transports the medium5.

The motor3is configured to transmit a driving force to all of rotation shafts35,37,39, and19corresponding to the upper first transporting roller23, the lower first transporting roller27, the upper second transporting roller29, and the lower second transporting roller33, respectively.

Note that as shown inFIG.3, each of the upper first transporting roller23, the lower first transporting roller27, the upper second transporting roller29, and the lower second transporting roller33is composed of two rollers located at two locations spaced apart from each other in the axial direction of the rotation shafts35,37,39, and19.

In the embodiment, the encoder scale13is provided on the rotation shaft19of the lower second transporting roller33.

The dimensions of the outer shape of the image reading device1in the depth direction are formed as follows. That is, as shown inFIG.1, the length Ld in the depth direction of the image reading device1at the position Pd (FIGS.1and2), where the second transporting roller11is provided, is longer than the length Lu in the depth direction of the image reading device1at the position Pu (FIGS.1and2), where the first transporting roller9is provided, that is, Ld>Lu.

In other words, the second transporting roller11is disposed inside the image reading device1at a position where the dimension in the depth direction is longer than at the position of the first transporting roller9.

Note that the encoder scale13may be provided on the rotation shaft39of the upper second transporting roller29. As a power transmission path from the motor3, the power may be transmitted to one of the rotation shafts35or37of the first transporting roller9, and then transmitted to the rotation shafts19and39of the second transporting roller11via a transmission gear.

Two Wheel Drive

In the present embodiment, as described above, two wheel drive configuration is adopted in which all of the upper first transporting roller23, the lower first transporting roller27, the upper second transporting roller29, and the lower second transporting roller33are rotated by one motor3.

The structure of the two wheel drive is specifically configured as follows. As shown inFIGS.3and4, the driving force of the motor3is transmitted to the lower first transporting roller27and the upper second transporting roller29via the rotation shaft19of the lower second transporting roller33. Further, it is transmitted to the upper first transporting roller23via the rotation shaft39of the upper second transporting roller29.

Here, a gear36is mounted on the −X direction end portion of the rotation shaft19. A gear38, a gear40, and a gear42are mounted on the −X direction end portions of the rotation shaft37, the rotation shaft39, and the rotation shaft35, respectively. The rotation of the gear36is transmitted to the gear38through a transmission gear44. The rotation of the gear36is directly transmitted to the gear40. The rotation of the gear40is transmitted to the gear42via a transmission gear46.

As shown inFIG.3, the encoder scale13is provided on the rotation shaft19of the lower second transporting roller33, to which the driving force from the motor3is first transmitted.

The feed roller14includes a drive roller48and a retard roller50. In this embodiment, as shown inFIG.3, the driving force of the motor3is also transmitted to the feed roller14. Specifically, a gear54is mounted on the −X direction end portion of a rotation shaft52of the drive roller48. The rotation of the gear42is transmitted to the gear54via the transmission gear56. The intermediate roller20is constituted by a pair of a drive roller58and a driven roller60. A gear64is mounted on the −X direction end portion of a rotation shaft62of the drive roller58. The discharge roller22is constituted of a pair of a drive roller66and a driven roller68. A gear72is mounted on the −X direction end portion of a rotation shaft70of the drive roller66. Rotation of the gear36is transmitted to a transmission gear74, a transmission gear76, and a transmission gear78in this order, and is transmitted from the last transmission gear78simultaneously to the gear64and the gear72.

In the embodiment, as shown inFIGS.3and4, the upper second transporting roller29and the lower second transporting roller33are provided between a universal joint41, which is a universal coupling, and the encoder scale13in the direction of the rotation shaft39.

Here, the rotation shaft35of the upper first transporting roller23is also provided with universal joints43and43. The universal joints are provided on both sides for transmission shafts80and82, so that the upper first transporting roller23and the upper second transporting roller29can be driven by the motor3while being displaced with respect to the opposing rollers.

In the present embodiment, a medium detection section45and a control section47are provided upstream of the reading section7.

The medium detection section45is disposed near the first nip position25of the first transporting roller9, and is configured to accurately detect the timing at which the leading end and the trailing end of the medium5pass through the nip position25. Here, an optical sensor is used as the medium detection section45, and the medium detection section45is configured by a known pair of a light emitting section and a light receiving section.

The control section47includes a CPU, a flash ROM, and a RAM. The CPU performs various kinds of arithmetic processing in accordance with a program stored in the flash ROM and controls the operation of the entire image reading device1. A flash ROM, which is an example of the storage means, is a nonvolatile memory capable of reading and writing. Various kinds of information are temporarily stored in the RAM, which is an example of the storage means.

The control section47uses the measuring section17, including the encoder scale13and the encoder sensor15, to measure a current distance b after the medium5passes through the medium detection section45, and uses a calculation section (not illustrated) to calculate a difference distance c between the current distance b and a target distance a, which is stored in advance. Then, in the image data read by the reading section7, a position at which the difference distance c exists is specified, and image correction is performed on the specified position. Here, the control section also controls the driving of the motor3. That is, it controls the operation of each transporting roller.

FIG.6is a graph in which the horizontal axis represents the time T elapsed since the start of measurement by the medium detection section45and the vertical axis represents the distance R that the medium5has moved. Here, a case is shown in which from time T1to time T2, there is a portion R1whose movement distance is larger than that immediately before and a portion R2whose movement distance is smaller than that immediately before.

FIGS.7A and7Bshow the measurement result ofFIG.6in terms of the shape change of the pixel.FIG.7Ashows a case where there is no differential distance c, that is, a case where the differential distance c is zero as a result of substantially regular movement at a target distance a, andFIG.7Bshows a case where there is a differential distance c, that is, the state shown inFIG.6.

FIG.8is a flowchart for explaining an image correction method performed by the control section47. First, in step S1, the current distance b, which is the distance by which the medium5has moved from the preset measurement start position, is measured by the measuring section17using the encoder scale13or the like. Subsequently, in step S2, a differential distance c, which is the difference between the current distance b and the target distance a, is calculated. Next, in Step S3, a position where the difference distance c is generated in the actual image read by the reading section7is specified. Further, image correction is performed on the image at that position, wherein the image correction is correcting the image data ofFIG.7Bas shown inFIG.7A. Note that the image correction is not limited to a specific correction method. For example, image correction may be performed by thinning out pixels at the specified positions.

In the present embodiment, as shown inFIG.2, a medium detection section53is also disposed near the second nip position31of the second transporting roller11.

The control section47is configured to execute the image correction based on measurement information measured by the measuring section17during a period from when the rear end of the medium5passes through the first nip position25to when the rear end of the medium5passes through the second nip position31. In other words, in a state where the rear end of the medium5has passed by the first transporting roller9and the medium5is transported while the rear end side of the medium5is supported only by the second transporting roller11, the image of the medium5read by the reading section7is set as a target of image correction.

In the present embodiment, as shown inFIGS.2and4, the encoder scale13is disposed so as to overlap with a portion of the second transporting roller11in the side view direction (X axis direction). In addition, a portion of the encoder scale13is disposed so as to overlap with the lower second transporting roller33in the side view direction. In addition, a portion of the encoder scale13is disposed so as to overlap with the reading section7in the side viewing direction. In addition, a portion of the encoder scale13is disposed so as to overlap with the transmission gear44and the transmission gear74in the side viewing direction (FIG.4). In addition, the encoder scale13is disposed so as to overlap with the gear6to which power is transmitted from the motor3via the belt2in the direction of the rotation shaft19. The encoder scale13and the motor3are disposed on the inner side (−X direction) of the belts2and4.

Description of Effects of the First Embodiment

(1) In the present embodiment, since the encoder scale13is provided on the rotation shaft19of the second transporting roller11, even when there is a disturbance in the movement amount of the medium5due to an instantaneous change in state when the rear end of the medium5passes beyond the first transporting roller9, it is possible to detect the disturbance. Thus, it is possible to reduce the deterioration of the image quality.

Since the encoder scale13is disposed on the rotation shaft19of the second transporting roller11, the space efficiency is increased, which leads to miniaturization of the apparatus.

(2) According to the present embodiment, since the driving force is transmitted to the four rollers of the upper first transporting roller23, the lower first transporting roller27, the upper second transporting roller29, and the lower second transporting roller33, it is possible to measure the movement distance of the medium5in a state where the transporting force is improved. As a result, slippage of the rollers is suppressed, so that the measurement accuracy of the moving distance of the medium5is improved.

In addition, since the encoder scale13is provided on the rotation shaft19of the lower second transporting roller33having the greatest amount of margin in the depth direction among the four rollers, the space utilization efficiency is improved.

(3) According to the present embodiment, since the measuring section17is disposed on the rotation shaft19which is a driving shaft to which the driving force from the motor3reaches previously, the measurement accuracy of the movement distance of the medium5is improved.

(4) According to the present embodiment, the upper second transporting roller29and the lower second transporting roller33are provided between the universal joints41,43and the encoder scale13in the rotation axis direction. That is, since the universal joints41and43and the encoder scale13are provided on opposite sides in the rotational axis direction, the size of the apparatus can be reduced.

(5) According to the present embodiment, the control section47specifies the position where the difference distance c is present in the image data read by the reading section7, and executes the image correction on the specified position. By this image correction, it is possible to reduce the influence of the disturbance of the image, thereby reducing the deterioration of the image quality.

(6) According to the present embodiment, the image correction is executed based on the measurement information measured by the measuring section17during a period from when the rear end of the medium5passes through the first nip position25to when the rear end of the medium5passes through the second nip position31. By this, even if there is a disturbance in the movement amount of the medium5due to an instantaneous change in state when the rear end of the medium5passes through the first nip position25and the medium5changes to transport state of only one end being held by the second nip position31, image correction is executed by detecting the disturbance, and thus it is possible to reduce deterioration in image quality.

Second Embodiment

An image reading device1according to the second embodiment will be described below. The same portions as those in the first embodiment are denoted by the same reference numerals, and the description of the configuration and the corresponding effects is omitted.

In the present embodiment, the second transporting roller11consists of a drive roller33(it is indicated by the same reference numeral33because it corresponds to the lower second transporting roller33inFIG.2) rotated by the motor3, and the driven roller29(it is indicated by the same reference numeral29because it corresponds to the upper second transporting roller29inFIG.1) driven and rotated by the driving roller33. In other words, in the first embodiment, the second transporting roller11has a two wheel drive structure as described above, but in the present embodiment, the second transporting roller11is formed to have a non-two wheel drive or one wheel drive configuration in which one of the rollers is the driven roller29. As shown inFIG.5A, the encoder scale13is disposed on the rotation shaft19of the drive roller33.

As shown inFIG.5B, the encoder scale13may be arranged on the rotation shaft39of the driven roller29.

According to the present embodiment, since the encoder scale13is disposed on the rotation shaft19of the drive roller33, it is possible to measure the movement distance of the medium5.

In a case where the encoder scale13is disposed on the rotation shaft39of the driven roller29, it is possible to more accurately measure the movement distance of the medium5.

Third Embodiment

Hereinafter, an image reading device1according to the third embodiment will be described with reference toFIGS.2and9. The same portions as those in the first embodiment are denoted by the same reference numerals, and the description of the configuration and the corresponding effects is omitted.

As shown inFIG.2, in the present embodiment, the medium5is transported in the transport direction F and with respect to the transport direction F, it is provided with a third transporting roller20, which is the intermediate roller20provided downstream of the second transporting roller11, a first transporting path49that is for transporting the medium5and that includes from the nip position25of the first transporting roller9to the nip position31of the second transporting roller11, and a second transporting path51that is for transporting the medium5and that includes from the nip position31of the second transporting roller11to a nip position55of the third transporting roller20.

In the present embodiment, the motor3is a DC motor, the first transporting path49includes a linear path, and the second transporting path51includes a curved path.

Then, as shown inFIG.9A, the control section47stops the transport of the medium5when the load G of the DC motor3exceeds the threshold value Q. A threshold value Q2when the medium5is transported along the second transporting path51is set to be larger than a threshold value Q1when the medium5is transported along the first transporting path49. Specifically, it is desirable that the threshold value Q2of the second transporting path is used when the leading end of the medium5enters the second transporting path51, and the threshold value Q1of the first transporting path49is used before that.

InFIGS.9A and9B, the horizontal axis represents the transport distance L and the vertical axis represents the transporting load P. In other words, since the transporting load of the DC motor3is larger in the case where the transporting path is the “curved path” than in the case where the transporting path is the “straight path”, the threshold value is set in accordance with a change in the magnitude of the transporting load.

Here, since a third transporting path57downstream of the second transporting path51can also be said to be a “straight path”, the threshold value Q3of that portion is set smaller than the threshold value Q2.

InFIG.9A, the thresholds Q1and Q3are not flat but stepwise for the following reason. That is, as shown inFIG.9B, the load G of the DC motor3is larger in the state G2in which the medium5is transported by two rollers than in the state G1in which the medium5is transported by one transporting roller. This point will be further described later.

In this specification, the “straight path” does not need to be strictly a straight line, but includes a path that can be regarded as a substantially straight line.

Note that inFIG.9, reference characters J1and J2indicate related art's thresholds which are set regardless of a change in the transporting load.

In the present embodiment, as shown inFIG.2, two medium detection sections45and53are provided to detect that the leading end and the trailing end of the medium5have passed through the first transporting roller9and the second transporting roller11, respectively. The control section47is configured to, based on the combination of the detection information of the medium detection sections45and53, raise the threshold Q when the number of detections increases and to lower the threshold Q when the number of detections decreases.

In other words, based on the combination of detection information from the medium detection sections45and53, a state in which the medium5is transported by only the first transporting roller9(G1inFIG.9B), a state in which the medium5is transported by both of the first transporting roller9and the second transporting roller11, that is, a state in which “the number of detections increases” (G2inFIG.9B), and a state in which the medium5is transported by only the second transporting roller11(G3inFIG.9B) can be distinguished. Since this distinction can be made, the threshold value can be raised or lowered as described above.

That is, as described above with reference toFIG.9A, the thresholds Q1and Q3are not flat but stepwise.

If there are three or more transport rollers, three or more medium detection sections may be provided in accordance with the number of transporting rollers.

In the present embodiment, as shown inFIG.2, the second transporting path51includes a first curved path59having a first curvature and a second curved path61having a second curvature larger than the first curvature. Accordingly, the transporting load of the DC motor3when the medium5is transported on the second curved path51is larger than the transporting load of the DC motor3when the medium5is transported on the first curved path59.

The control section47is configured to use a first threshold value in the first curved path59having the first curvature, and use a second threshold value larger than the first threshold value in the second curved path51having the second curvature.

In a case where the medium5is transported across both the second curved path61and the second curved path51, a second threshold value which is a larger one of the threshold values Q may be used.

In the present embodiment, the third transporting roller20includes a lower third transporting roller58which is the drive roller58which is driven by the motor3and transports the medium5, and an upper third transporting roller60which is a driven roller60which is driven and rotated by the lower third transporting roller58and transports the medium5by interposing the medium5between the lower third transporting roller58and the third nip position55.

The threshold value Q when the medium5is transported by the first transporting roller9or the second transporting roller11is set to be larger than the threshold value when the medium5is transported only by the third transporting roller20.

In the present embodiment, as shown inFIG.2, the first transporting path49and the second transporting path51are disposed so as to overlap with a portion of the encoder scale13in the side viewing direction. The encoder scale13is disposed so as to overlap with a portion of the second curved path in the side viewing direction.

Difference in Thickness of Medium and Threshold Values

FIGS.10A and10Bshow that different threshold values Q are set for a thick medium and a thin medium of the medium5.

Reference numeral91indicates a transporting load of a thick medium, reference numeral92indicates a transporting load of a thin medium, and reference numeral93indicates a transporting load in a state where the medium5is not present. The transporting load corresponds to the transporting force of the DC motor3. InFIG.10A, the difference between the transporting loads91,92, and93on the left side corresponds to a state where the medium5is transported only by the feeding roller (ALD)14. The transporting loads91,92, and93in the central portion ofFIG.10Aindicate a state in which the medium5is further transported by the first transporting roller (ADF)9and the second transporting roller (ADF)11. As illustrated inFIG.10B, the difference in the transporting load only by the feed roller14is also affected in a state where the medium5is transported by the first transporting roller9or the like, and a similar difference occurs.

Therefore, different threshold values Q4, Q5, and Q6are set so that the difference is constant (the difference value of 100 inFIG.10B), such that the threshold value Q is Q4for a thick medium, Q5for a thin medium, and Q6when there is no medium.

Two Wheel Drive, One Wheel Drive, and Thresholds

FIG.11shows that different threshold values Q are set for two wheel drive and one wheel drive of the first transporting roller9and the like.

InFIG.11A, reference numeral94denotes the transporting load in the case of the one wheel drive, and reference numeral95denotes the transporting load in the case of two wheel drive. In two wheel drive, since the transporting force of the DC motor3with respect to the medium5increases, the transporting load becomes smaller than that in the one wheel drive.

Therefore, the threshold value Q is set to a different value, for example, Q7for one wheel drive and Q8for two wheel drive.

FIG.11Bshows a case where medium clogging occurs at the position NG. As shown in the figure, since the rising action97of the transporting load95with two wheel drive is faster than the rising action96of the transporting load94with one wheel drive, the responsiveness of the detection of the medium jam is improved.

Description of Effects of the Third Embodiment

(1) In the present embodiment, the control section47determines that the threshold value Q2when the medium5is transported along the second transporting path51is larger than the threshold value when the medium5is transported along the first transporting path49. That is, since a plurality of threshold values of the transporting load is provided, when the transport of the medium5has to be stopped, the transport of the medium5can be stopped earlier than in the prior art, thereby suppressing damage to the medium5.

(2) According to the present embodiment, based on the combination of the detection information of the plurality of medium detection sections45and53, the control section47increases the threshold value Q when the number of detections increases, and decreases the threshold value Q when the number of detections decreases. Accordingly, since a plurality of appropriate threshold values can be used, the conveyance can be stopped earlier than in the case of using a fixed threshold value, and damage to the medium5can be suppressed.

(3) According to the present embodiment, the control section47uses the first threshold value in the first curved path59having the first curvature, and uses the second threshold value larger than the first threshold value in the second curved path61having the second curvature larger than the first curvature. By this, since it is possible to use a plurality of appropriate threshold values, it is possible to stop the transport of the medium5at an early stage and to suppress damage to the medium5compared to a case where a fixed threshold value is used.

(4) According to the present embodiment, the threshold value Q in a case where the medium5is transported by the first transporting roller9or the second transporting roller11is larger than the threshold value in a case where the medium5is transported by only the third transporting roller20. Accordingly, since it is possible to use a plurality of appropriate threshold values according to the transporting load, it is possible to stop the transport of the medium5earlier than in a case where a fixed threshold value is used, and to suppress damage to the medium5.

(5) According to the embodiment, the first transporting path49and the second transporting path51are disposed so as to overlap with a portion of the encoder scale13in the side viewing direction. That is, by arranging the encoder scale13so as to partially overlap with the first transporting path49and the second transporting path51, the space efficiency is improved, leading to miniaturization of the apparatus.

OTHER EMBODIMENTS

The image reading device1according to the present disclosure basically has the configuration of the embodiments described above, but it is of course possible to change or omit a portion of the configuration without departing from the scope of the present disclosure.

Since the first embodiment and the second embodiment have been described above with reference toFIG.2, the second transporting path51located downstream of the second transporting roller11in the transporting direction F is a reversing path or a curved path. However, in the first embodiment and the second embodiment, the second transporting path does not need to be the inversion path, and may be a substantially linear path. The first transporting path49may be curved, instead of straight, upstream of the first transporting roller9.