Sheet conveyance apparatus, image reading apparatus, and image forming apparatus

1 . A sheet conveyance apparatus comprising:

a supporting tray on which a sheet is supported;

a conveyance unit configured to convey the sheet in a conveyance direction, the conveyance unit including a rotating member and a separation portion together configured to separate sheets supported on the supporting tray one by one;

a sensor unit including:

a first sensor configured to detect the sheet conveyed by the conveyance unit at a first detection position; and

a second sensor configured to detect the sheet conveyed by the conveyance unit at a second detection position that is different from the first detection position in a width direction orthogonal to the conveyance direction; and

a control unit configured to:

execute a first stop processing of stopping conveyance of the sheet by the conveyance unit in a case where, until a threshold value time has elapsed after one of the first sensor or the second sensor has detected the sheet, the other one of the first sensor or the second sensor does not detect the sheet;

execute a speed detection processing of measuring a speed of the sheet conveyed by the conveyance unit based on a detection result of the sensor unit;

set the threshold value time to:

a first time in a case where the speed of the sheet measured in the speed detection processing is a first speed; and

a second time that is longer than the first time in a case where the speed of the sheet measured in the speed detection processing is a second speed that is slower than the first speed.

2 . The sheet conveyance apparatus according to claim 1 , wherein:

the sensor unit includes a third sensor configured to detect the sheet conveyed by the conveyance unit at a third detection position that is different from the first detection position and the second detection position in the conveyance direction, and

the control unit is configured to execute the speed detection processing based on a time difference between a timing at which one of the first sensor or the second sensor detects the sheet and a timing at which the third sensor detects the sheet.

3 . The sheet conveyance apparatus according to claim 1 , wherein:

the sensor unit includes:

a third sensor configured to detect the sheet conveyed by the conveyance unit at a third detection position; and

a fourth sensor configured to detect the sheet at a fourth detection position that is different from the third detection position in the conveyance direction, and

the control unit is configured to execute the speed detection processing based on a first time difference between a timing at which the third sensor detects the sheet and a timing at which the fourth sensor detects the sheet.

4 . The sheet conveyance apparatus according to claim 3 , wherein:

the fourth detection position is arranged downstream of the first detection position and the second detection position in the conveyance direction, and

the control unit is configured to:

acquire a second time difference between a timing at which the first sensor detects the sheet and a timing at which the second sensor detects the sheet;

execute the speed detection processing based on the first time difference;

modify the threshold value time based on a speed of the sheet acquired in the speed detection processing; and

execute the first stop processing in a case where the second time difference exceeds the threshold value time that has been modified.

5 . The sheet conveyance apparatus according to claim 1 , wherein, in a state where a speed of the sheet being measured is slower than a threshold value speed, the control unit is configured to selectively execute a first mode of executing the first stop processing or a second mode of not executing the first stop processing.

6 . The sheet conveyance apparatus according to claim 5 , wherein the control unit is configured to execute:

a second stop processing of stopping conveyance of the sheet by the conveyance unit before selection of the first mode or the second mode in a case where a speed of the sheet being measured is slower than the threshold value speed; and

a selected mode after the first mode or the second mode has been selected after executing the second stop processing.

7 . The sheet conveyance apparatus according to claim 5 , wherein, after the second mode has been selected, in a state where a speed of the sheet conveyed by the conveyance unit changes to be equal to or faster than the threshold value speed, the control unit is configured to automatically switch the second mode to the first mode and execute the first mode.

8 . The sheet conveyance apparatus according to claim 1 , wherein the control unit is configured to modify the threshold value time based on a measured value of a speed of the sheet acquired in the speed detection processing once.

9 . The sheet conveyance apparatus according to claim 1 , wherein the control unit is configured to execute the speed detection processing for multiple times, and modify the threshold value time based on an average value that has been calculated from measured values of speed of the sheet acquired in each of the speed detection processing.

10 . An image reading apparatus comprising:

the sheet conveyance apparatus according to claim 1 ; and

an image reading unit configured to read an image formed on a sheet conveyed by the sheet conveyance apparatus.

11 . An image forming apparatus comprising:

the image reading apparatus according to claim 10 ; and

an image forming unit configured to form an image on a sheet based on an information of an image read by the image reading apparatus.

12 . A sheet conveyance apparatus comprising:

a supporting tray on which a sheet is supported;

a conveyance unit configured to convey the sheet in a conveyance direction, the conveyance unit including a rotating member and a separation portion together configured to separate sheets supported on the supporting tray one by one;

a sensor unit including:

a first sensor configured to detect the sheet conveyed by the conveyance unit at a first detection position; and

a second sensor configured to detect the sheet conveyed by the conveyance unit at a second detection position that differs from the first detection position in a width direction orthogonal to the conveyance direction; and

a control unit configured to:

execute a first stop processing of stopping conveyance of the sheet by the conveyance unit in a case where skewing of the sheet has been detected based on a detection result of the sensor unit;

execute a speed detection processing of measuring a speed of the sheet conveyed by the conveyance unit based on the detection result of the sensor unit; and

in a state where the speed of the sheet measured in the speed detection processing is slower than a threshold value speed:

execute a second stop processing of stopping conveyance of the sheet by the conveyance unit; and

after executing the second stop processing, selectively execute a first mode of executing the first stop processing or a second mode of not executing the first stop processing.

13 . The sheet conveyance apparatus according to claim 12 , wherein:

the sensor unit includes a third sensor configured to detect the sheet conveyed by the conveyance unit at a third detection position that is different from the first detection position and the second detection position in the conveyance direction, and

the control unit is configured to execute the speed detection processing based on a time difference between a timing at which one of the first sensor or the second sensor detects the sheet and a timing at which the third sensor detects the sheet.

14 . The sheet conveyance apparatus according to claim 12 , wherein:

the sensor unit includes a third sensor configured to detect the sheet conveyed by the conveyance unit at a third detection position, and a fourth sensor configured to detect the sheet at a fourth detection position that is different from the third detection position in the conveyance direction, and

the control unit is configured to execute the speed detection processing based on a first time difference between a timing at which the third sensor detects the sheet and a timing at which the fourth sensor detects the sheet.

15 . The sheet conveyance apparatus according to claim 14 , wherein:

the fourth detection position is arranged downstream of the first detection position and the second detection position in the conveyance direction, and

the control unit is configured to:

acquire a second time difference between a timing at which the first sensor detects the sheet and a timing at which the second sensor detects the sheet;

execute the speed detection processing based on the first time difference;

modify a threshold value time based on a speed of the sheet acquired in the speed detection processing, and

execute the first stop processing in a case where the second time difference exceeds the threshold value time that has been modified.

16 . The sheet conveyance apparatus according to claim 12 , wherein, after the second mode has been selected, if a speed of the sheet conveyed by the conveyance unit changes to be equal to or faster than the threshold value speed, the control unit is configured to automatically switch the second mode to the first mode and execute the first mode.

17 . The sheet conveyance apparatus according to claim 12 , wherein the control unit is configured to modify a threshold value time based on a measured value of a speed of the sheet acquired in the speed detection processing once.

18 . The sheet conveyance apparatus according to claim 12 , wherein the control unit is configured to execute the speed detection processing for multiple times, and modify a threshold value time based on an average value that has been calculated from measured values of speed of the sheet acquired in each of the speed detection processing.

19 . An image reading apparatus comprising:

the sheet conveyance apparatus according to claim 12 ; and

an image reading unit configured to read an image formed on a sheet conveyed by the sheet conveyance apparatus.

20 . An image forming apparatus comprising:

the image reading apparatus according to claim 19 ; and

an image forming unit configured to form an image on a sheet based on an information of an image read by the image reading apparatus.