Paper sheet detection device, paper sheet detection method, and paper sheet processing device

1. A paper sheet detection device comprising:

an optical sensor that includes a light-emitting portion that emits light, and a light-receiving portion that receives the emitted light;

a storage portion that stores a first threshold value used for determining whether or not a paper sheet is present in a path of the emitted light, a target light-receiving level set as a target value of a level of the light received by the light-receiving portion in a state where the paper sheet is not present, and a second threshold value that is set to a value that is greater than the first threshold value and less than the target light-receiving level;

an estimating portion that determines whether the level of the light received by the light-receiving portion is equal to or greater than the first threshold value and less than the second threshold value, and that estimates whether or not the paper sheet is present; and

a light amount adjusting portion that adjusts an amount of the light emitted by the light-emitting portion so that the level of the light received by the light-receiving portion becomes the target light-receiving level in the state where the paper sheet is not present when the estimating portion estimates that the paper sheet is not present after the estimating portion determines that the level of the light received by the light-receiving portion is equal to or greater than the first threshold value and less than the second threshold value.

2. The paper sheet detection device according to claim 1 , further comprising:

a reporting portion that reports information indicating that there is a possibility that the paper sheet is present when the level of the light received by the light-receiving portion is determined to be equal to or greater than the first threshold value and lower than the second threshold value; and

an operation portion that receives a confirmation operation for the reporting,

wherein the estimating portion estimates that the paper sheet is not present when the confirmation operation has been received by the operation portion.

3. The paper sheet detection device according to claim 1 , further comprising:

a reporting portion that reports information indicating that there is a possibility that the paper sheet is present when the level of the light received by the light-receiving portion is determined to be equal to or greater than the first threshold value and lower than the second threshold value,

wherein the estimating portion estimates that the paper sheet is not present when a certain period of time has elapsed since the information is reported.

4. The paper sheet detection device according to claim 1 , wherein the estimating portion estimates whether or not the paper sheet is present based on a first light-receiving level that is the level of the light received by the light-receiving portion at a first time and a second light-receiving level that is the level of the light received by the light-receiving portion at a second time after the first time.

5. The paper sheet detection device according to claim 1 ,

wherein the paper sheet includes a non-transparent region and a transparent region, and

the first threshold value is set to a value at which the non-transparent region of the paper sheet is detectable, and the second threshold value is set to a value at which the transparent region of the paper sheet is detectable.

6. The paper sheet detection device according to claim 5 , wherein the target light-receiving level is set to a value lower than a target value of the level of the light received by the light-receiving portion in a state of a paper sheet without a transparent region not being present in the path of the emitted light.

7. The paper sheet detection device according to claim 5 , wherein the target light-receiving level is changeable.

8. A paper sheet processing device comprising:

the paper sheet detection device according to claim 1 ;

a receiving portion that receives charging of the paper sheet;

a stacking portion that is provided with the paper sheet detection device and that stores the paper sheet;

an identifying and counting portion that identifies and counts the paper sheet; and

a sorting portion that sorts the paper sheet that have been identified and counted by the identifying and counting portion to the stacking portion.

9. A paper sheet detection method comprising:

emitting light by a light-emitting portion;

receiving the emitted light by a light-receiving portion;

determining whether a level of the light received by the light-receiving portion is equal to or greater than a first threshold value and less than a second threshold value, the first threshold value being used for determining whether or not a paper sheet is present in a path of the emitted light, the second threshold value being set to a value less than a target light-receiving level set as a target value of the level of the light received by the light-receiving portion in a state where the paper sheet is not present;

estimating whether or not the paper sheet is present; and

adjusting an amount of the light emitted by the light-emitting portion so that the level of the light received by the light-receiving portion becomes the target light-receiving level in the state where the paper sheet is not present when it is estimated that the paper sheet is not present after it is determined that the level of the light received by the light-receiving portion is equal to or greater than the first threshold value and less than the second threshold value.

10. The paper sheet detection method according to claim 9 , further comprising:

reporting information indicating that there is a possibility that the paper sheet is present when the level of the light received by the light-receiving portion is determined to be equal to or greater than the first threshold value and less than the second threshold value; and

receiving a confirmation operation for the reporting,

wherein it is estimated that the paper sheet is not present when the confirmation operation has been received.