Paper folding device for three-folding sheet of paper

1. A paper folding device, comprising;

a first folding unit for forming a first folding line on paper fed to a first feeding position;

a first driving unit for driving said first folding unit for forming said first folding line on said paper;

a first feeding unit for feeding the paper, having said first folding line formed by said first folding unit, to a second feeding position;

a second folding unit for forming a second folding line on the paper fed to said second feeding position; and

a second driving unit for driving said second folding unit for forming said second folding line on said paper; wherein

said first folding unit includes a pair of rollers, and a knife-shaped first folding plate member pushing said first folding line to said pair of rollers; and

said first driving unit moves said first folding plate member to the paper fed to said first feeding position until load on said first folding plate member exceeds a prescribed value;

said device further comprising;

an obtaining unit obtaining a characteristic of said paper; and

a determining unit for determining a time period from start of driving of said first folding unit by said first driving unit to start of driving of said second folding unit by said second driving unit, based on the characteristic of paper obtained by said obtaining unit.

2. The paper folding device according to claim 1 , wherein

the time period determined by said determining unit becomes longer when number of sheets of paper as said characteristic of paper increases.

3. The paper folding device according to claim 1 , wherein

the time period determined by said determining unit becomes longer when thickness of paper as said characteristic of paper increases.

4. The paper folding device according to claim 1 , wherein

said obtaining unit is communicable with a paper feeding apparatus feeding paper to said first feeding position; and

obtains the characteristic of paper fed to said first feeding position, from said paper feeding apparatus.

5. The paper folding device according to claim 4 , wherein

said paper feeding apparatus is an image forming apparatus having formed an image on the paper fed to said first feeding position.

6. The paper folding device according to claim 1 , wherein

said first feeding unit is also implemented by said pair of rollers.

7. The paper folding device according to claim 1 , wherein

said first feeding unit starts an operation of feeding said paper at a timing having a prescribed relation from start of movement of said first folding plate member by said first driving unit; and

said second driving unit starts driving of said second folding unit, on condition that the time period determined by said determining unit has passed after the start of operation for feeding the paper by said first feeding unit.

8. The paper folding device according to claim 1 , wherein

said second folding unit includes a knife-shaped second folding plate member for forming said second folding line on the paper fed to said second feeding position; and

said second driving unit drives said second folding unit by moving said second folding plate member to the paper fed to said second feeding position.

9. The paper folding device according to claim 8 ,

wherein said first driving unit begins moving said first folding plate member toward said paper positioned in said first feeding position at said start of driving of said first folding unit and said second driving unit begins moving said second folding plate member toward said paper positioned in said second feeding position at said start of driving of said second folding unit so that said time period is a length of time between a start of movement of said first folding plate and a start of movement of said second folding plate.

10. The paper folding device according to claim 1 , wherein

said first feeding unit starts an operation of feeding the paper, having said first folding line formed, to said second feeding position, on condition that the time period determined by said determining unit has passed from when said first driving unit started driving of said first folding unit.

11. The paper folding device according to claim 1 , further comprising

a storage unit for storing the time period from the start of driving of said first folding unit to the start of driving of said second folding unit in association with the characteristic of paper; wherein

said determining unit determines the time period from the start of driving of said first folding unit to the start of driving of said second folding unit to be the time period stored in said storage unit in association with the characteristic of paper obtained by said obtaining unit.

12. The paper folding device according to claim 1 ,

wherein said first driving unit begins moving said first folding plate member toward said paper positioned in said first feeding position at said start of driving of said first folding unit.