1. A discharge controller comprising:
a secondary battery;
a switch section for openingclosing a discharge path from said secondary battery to a load;
a voltage detector for detecting a terminal voltage of said secondary battery; and
a cut-off voltage control section for controlling the switch section to be opened when the terminal voltage as detected by the voltage detector is not more than a predetermined cut-off voltage of discharge VE, while measuring an amount of decrease per unit time of the terminal voltage as detected by said voltage detector to set the cut-off voltage of discharge VE to a lower voltage, for a larger amount of decrease per unit time of the terminal voltage as detected by said voltage detector.
2. The discharge controller according to claim 1, wherein:
said cut-off voltage control section measures the amount of decrease in the terminal voltage as an amount of change in voltage Vx in a predetermined measurement time t, and uses a value obtained by dividing the amount of change in voltage Vx by the measurement time t as the amount of decrease per unit time of the terminal voltage.
3. The discharge controller according to claim 2, wherein:
said secondary battery is a nonaqueous-electrolyte secondary battery.
4. The discharge controller according to claim 3, wherein:
said cut-off voltage control section sets the cut-off voltage of discharge VE from the following expression (1):
VE=\u03b2\u2212\u03b1\xd7(Vxt)2\u2003\u2003(1)
in the expression (1), \u03b1 falls in a range of :5\u2266\u03b1\u226625, and \u03b2 falls in a range of 1.5\u2266\u03b2\u22663.0.
5. The discharge controller according to claim 3, wherein:
said secondary battery is made up of assembled cells wherein plurality of cells are connected in series; and
said cut-off voltage control section sets the cut-off voltage of discharge VE from the following expression (2):
VE={\u03b2\u2212\u03b1\xd7(Vxt)2}\xd7X\u2003\u2003(2)
in the expression (2), X indicates a number of cells connected in series, \u03b1 falls in a range of :5\u2266\u03b1\u226625, and \u03b2 falls in a range of 1.5\u2266\u03b2\u22663.0.
6. The discharge controller according to claim 1, wherein:
said cut-off voltage control section measures the amount of decrease per unit time of the terminal voltage when the terminal voltage as detected by said voltage detector falls in a range not higher than 3.0 V and not less than 2.0 V per unit cell of the secondary battery, and not more than a predetermined threshold voltage.
7. The discharge controller according to claim 1, wherein:
said secondary battery is regulated with a positive electrode capacity such that the discharge ends by the decrease in potential of the positive electrode at the end of discharge.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A portable electronic device comprising: a main body including an end wall and a top surface connected to each other, the end wall defining a through hole, a recessed portion formed in the top surface; and a stamp structure including a seat and a stamp, the seat including a main plate and an end plate, the main plate defining a containing groove for receiving the stamp, the seat being detachably attached to the recessed portion of the main body, and the end plate abutting against the end wall and covering the through hole; and a cover detachably attached to the main body, the cover defining an engaging groove for allowing the main plate of the seat to extend through, wherein the recessed includes a bottom surface, the main plate includes a holding portion which defines the containing groove, and the recessed portion defines a receiving groove in the bottom surface for receiving the holding portion, wherein the end plate is integrally formed with the main plate and vertically extends from one end of the main plate, and the holding portion is positioned between the end plate and the latching portion.
2. The portable electronic device as claimed in claim 1, wherein the seat defines a slot between the holding portion and the end plate, a protrusion is formed at the bottom surface of the recessed portion, and the protrusion is engaged in the slot.
3. The portable electronic device as claimed in claim 1, wherein the end plate comprises a seal inserted in the through hole.
4. The portable electronic device as claimed in claim 3, wherein the end plate defines a cutout at one end thereof far away from the main plate.
5. A portable electronic device comprising: a main body defining a recessed portion at an end portion thereof, the recessed portion including a bottom surface and defining a stepped hole in the bottom surface; a seat including a main plate and an end plate, the main plate including a holding portion which defines a containing groove, a receiving groove defined in the bottom surface for receiving the holding portion, the seat being detachably attached to the main body, the end plate vertically extending from one end of the main plate, and the main plate received in the recessed portion, the main plate further comprising a latching portion far away from the end plate, and the latching portion detachably engaged in the stepped hole; and a stamp received in the containing groove of the seat, wherein the seat defines a slot between the holding portion and the end plate, a protrusion is formed at the bottom surface of the recessed portion, and the protrusion is engaged in the slot.
6. The portable electronic device as claimed in claim 5, wherein the main body includes an end wall, the end wall defines a through hole, the recessed portion extends to the end wall and is under the through hole, and the end plate of the seat covers the through hole.
7. The portable electronic device as claimed in claim 6, wherein the end plate comprises a seal inserted in the through hole.
8. The portable electronic device as claimed in claim 7, wherein the end plate defines a cutout at one end thereof far away from the main plate.
9. The portable electronic device as claimed in claim 5, wherein the end plate is integrally formed with the main plate.
10. The portable electronic device as claimed in claim 5, further comprises a cover detachably attached to the main body, wherein the cover defines an engaging groove for allowing the main plate of the seat to extend through.