Medium conveying apparatus for detecting a folding of a medium

1. A medium conveying apparatus comprising:

a housing;

a medium tray;

a feed roller to feed a medium on the medium tray;

a first optical sensor including a first light emitter for emitting first light and a first light receiver for generating a first signal based on receiving the first light;

a second optical sensor located apart from the first optical sensor in a direction perpendicular to the medium conveying direction, and including a second light emitter for emitting second light and a second light receiver for generating a second signal based on receiving the second light; and

a processor to

detect an abnormality of the medium based on at least the first signal or the second signal, wherein

the first light emitter emits the first light toward a downstream side of a predetermined position on the housing or the medium tray in the medium conveying direction, and wherein

the second light emitter emits the second light toward an upstream side of the predetermined position in the medium conveying direction.

2. The medium conveying apparatus according to claim 1 , wherein the second optical sensor is located on an upstream side of the first optical sensor in the medium conveying direction.

3. The medium conveying apparatus according to claim 1 , further comprising a pressing member to press the medium placed on the medium tray, wherein the first optical sensor and the second optical sensor are located on an upstream side of the pressing member in the medium conveying direction.

4. The medium conveying apparatus according to claim 1 , wherein the feed roller sequentially feeds the medium placed on the medium tray from a lowermost side.

5. The medium conveying apparatus according to claim 1 , wherein, when stopping feeding of the medium, the processor controls the feed roller in such a way that the medium is temporarily reset to the medium tray and is refed without being separated.

6. The medium conveying apparatus according to claim 1 , further comprising a medium detection sensor located on a downstream side of the feed roller in the medium conveying direction, wherein,

when the medium exists at a position of the medium detection sensor, the processor does not detect the abnormality of the medium.

7. The medium conveying apparatus according to claim 1 , wherein the processor detects the abnormality of the medium by comparing a signal value of the first signal at a predetermined timing with a signal value of the first signal or a signal value of the second signal at another timing.

8. The medium conveying apparatus according to claim 1 , wherein the processor detects a loaded amount of the medium on the medium tray based on the first signal, and wherein

the processor changes a sensitivity to detect the abnormality of the medium based on the loaded amount.

9. The medium conveying apparatus according to claim 1 , wherein the processor detects multi-feed of the medium, and wherein

the processor changes a sensitivity to detect the abnormality of the medium based on a detection result of multi-feed of the medium.

10. The medium conveying apparatus according to claim 1 , wherein the processor detects a skew of the medium, and wherein

the processor changes a sensitivity to detect the abnormality of the medium based on a detection result of a skew of the medium.

11. The medium conveying apparatus according to claim 1 , wherein the processor does not detect the abnormality of the medium when a variation of a signal value of the first signal or the second signal is greater than a threshold value.

12. The medium conveying apparatus according to claim 1 , further comprising a side guide, provided on the medium tray in such a way as to be movable in the direction perpendicular to the medium conveying direction, for regulating a width direction of the medium, wherein a height of the side guide is greater than a maximum loading capacity of the medium on the medium tray, and wherein

the processor does not detect the abnormality of the medium based on the second signal, when a height of the medium detected based on the second signal is greater than the maximum loading capacity.

13. A method for detecting an abnormality of a medium, comprising:

feeding the medium on a medium tray by a feed roller;

emitting first light by a first light emitter of a first optical sensor;

generating a first signal based on receiving the first light by a first light receiver of the first optical sensor;

emitting second light by a second light emitter of a second optical sensor located apart from the first optical sensor in a direction perpendicular to the medium conveying direction;

generating a second signal based on receiving the second light by a second light receiver of the second optical sensor; and

detecting the abnormality of the medium based on at least the first signal or the second signal, wherein

the first light emitter emits the first light toward a downstream side of a predetermined position on the housing or the medium tray in the medium conveying direction, and

the second light emitter emits the second light toward an upstream side of the predetermined position in the medium conveying direction.

14. The method according to claim 13 , wherein the second optical sensor is located on an upstream side of the first optical sensor in the medium conveying direction.

15. The method according to claim 13 , further comprising pressing the medium placed on the medium tray by a pressing member, wherein

the first optical sensor and the second optical sensor are located on an upstream side of the pressing member in the medium conveying direction.

16. The method according to claim 13 , wherein the medium placed on the medium tray is fed from a lowermost side by the feed roller, in the feeding step.

17. The method according to claim 13 , wherein, when stopping feeding of the medium, the feed roller is controlled in such a way that the medium is temporarily reset to the medium tray and is refed without being separated, in the stopping step.

18. The method according to claim 13 , wherein, when the medium exists at a position of a medium detection sensor located on a downstream side of the feed roller in the medium conveying direction, the abnormality of the medium is not detected, in the detecting step.

19. The method according to claim 13 , wherein the abnormality of the medium is detected by comparing a signal value of the first signal at a predetermined timing with a signal value of the first signal or a signal value of the second signal at another timing, in the detecting step.

20. A computer-readable, non-transitory medium storing a computer program, wherein the computer program causes a medium conveying apparatus including a housing, a medium tray, a feed roller to feed a medium on the medium tray, a first optical sensor including a first light emitter for emitting first light and a first light receiver for generating a first signal based on receiving the first light, a second optical sensor located apart from the first optical sensor in a direction perpendicular to the medium conveying direction, and including a second light emitter for emitting second light and a second light receiver for generating a second signal based on receiving the second light, to execute a process, the process comprising:

detecting an abnormality of the medium based on at least the first signal or the second signal, wherein

the first light emitter emits the first light toward a downstream side of a predetermined position on the housing or the medium tray in the medium conveying direction, the medium being placed on the medium tray, and

the second light emitter emits the second light toward an upstream side of the predetermined position in the medium conveying direction, the medium being placed on the medium tray.