Electricity: battery or capacitor charging or discharging – Battery or cell discharging – Regulated discharging
Reexamination Certificate
1999-09-28
2001-10-16
Toatley, Jr., Gregory J. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
Regulated discharging
C320S112000, C307S150000
Reexamination Certificate
active
06304064
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power supply device for and a power supply method of supplying power to electronic circuits by a battery, and electronic equipment provided with various electronic circuits, and a battery that supplies power to the electronic circuits, and specifically to a power supply device, a power supply method and electronic equipment wherein power is supplied to electronic circuits from a battery with decreased recharging capacity.
2. Background of the Invention
Typically, electronic equipment consists of electronic circuits that are driven by a battery or other power supply means. For example, portable electronic equipment, e.g. portable terminals, are driven by a primary battery or a rechargeable secondary battery.
Secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries and the like, and these nickel-cadmium batteries and nickel-hydrogen batteries have the advantages of a long history of practical use, high safety and low cost. Because of this, secondary batteries of nickel-cadmium batteries and nickel-hydrogen batteries have been used conventionally for driving electronic equipment.
However, nickel-cadmium batteries and nickel-hydrogen batteries have a disadvantage in that the so-called memory effect wherein voltage drops occur depending on their method of usage. The memory effect is an effect wherein the recharging capacity drops, a phenomenon that occurs for example when a deep discharge is performed after repeated shallow charging and discharging cycles, and then the voltage after discharge drops in two stages.
To explain this more specifically, the memory effect occurs particularly in sealed nickel-cadmium batteries or the like, when cycles of shallow discharging(discharging that ends before the capacity is completely regained) and recharging are repeated, the capacity is lost, leading to reversible deterioration. For example, as shown in
FIG. 1
, if cycles of partially discharging and recharging a battery are performed repeatedly, the voltage and capacity that can be obtained drop gradually with the number of cycles (curve
2
shows repeated cycles). If the battery is completely discharged thereafter (curve
3
), the discharge voltage drops compared to the initial characteristic obtained when the battery was discharged adequately (curve
1
). The discharge profile shows a two-stage change, and the battery does not regain its original capacity even when discharged to the original end voltage.
This phenomenon is known as “voltage depression.” Sometimes the battery may appear to remember the low capacity at the time of a shallow discharge, so it is also called the “memory effect.” This type of loss is accelerated as the temperature becomes higher.
The drop in capacity due to such a memory effect is different from substantial deterioration in that the original state can be restored by performing several complete discharge/recharge reconditioning cycles.
Therefore, as countermeasures against the memory effect, usage warnings to the effect that shallow charging and discharging should not be repeated are posted on products, and mechanisms are provided which occasionally perform deep discharges (to the completely discharged state) and return the battery to its initial state. However, each of these countermeasures is inconvenient for the user.
In addition, with the appearance of secondary batteries made of new materials, namely lithium ion batteries and lithium polymer batteries and the like, these batteries do not have the disadvantage of the memory effect seen in nickel-cadmium batteries and nickel-hydrogen batteries because they do not use the nickel anode said to be the main cause of the memory effect. However, these secondary batteries made of new materials do not have a long history of practical use, their safety is not adequately established, and additional circuitry is required for these countermeasures, and thus they have many disadvantageous aspects such as packaging aspects and cost aspects. In addition, there is an additional problem in that the cost of the cells themselves is higher than that of the conventional nickel-cadmium batteries and nickel-hydrogen batteries.
SUMMARY OF THE INVENTION
It is an object of the present invention to avoid the above disadvantages and provide a power supply device, a power supply method and electronic equipment that can be used even when power is supplied to electronic circuits using secondary batteries of nickel-cadmium batteries and nickel-hydrogen batteries or the like whose recharging capacities are operated, wherein the original performance of these secondary batteries can be maintained.
In order to solve the aforementioned problems and attain at the above object the power supply device according to the present invention comprises a voltage step-up means that steps up the output voltage from the storage means, and a supply means that supplies the stepped-up output voltage to the electronic circuit.
A power supply device having such a configuration supplies the output voltage from the storage means stepped up by the voltage step-up means to the electronic circuit by means of the supply means.
Thereby, with the power supply device of this invention, even in the case in which the memory effect occurs in the storage means, it is possible to obtain a discharge time close to the normal discharge time for an electronic circuit with a fixed voltage required for operation.
Moreover, in order to solve the aforementioned problems, in the power supply method according to the present invention the output voltage from a storage means with decreased recharging capacity is stepped up and this stepped-up output voltage is supplied as output to an electronic circuit.
Thereby, with the power supply method of the invention, even in the case in which the memory effect occurs in the storage means, it is possible to obtain a discharge time close to the normal discharge time for an electronic circuit with a fixed voltage required for operation.
In addition, in order to solve the aforementioned problems, the electronic equipment according to the present invention comprises a voltage step-up means that steps up the output voltage from a storage means with decreased recharging capacity, and an electronic circuit that is operated by the stepped-up output voltage.
Electronic equipment having such a configuration operates the electronic circuit by means of the output voltage from the storage means stepped up by the voltage step-up means.
Thereby, with this electronic equipment, even in the case in which the memory effect occurs in the storage means, it is possible to obtain a discharge time close to the normal discharge time for an electronic circuit with a fixed voltage required for operation.
In addition, the power supply circuit according to the present invention comprises at least one storage battery that has the memory effect, and a voltage step-up circuit that steps up the output voltage from the storage battery and supplies power to an electronic circuit, and is characterized in that the voltage step-up circuit has characteristics such that the tolerances of its input specifications are relatively wide compared to the tolerances of its output specifications.
Thereby, since the tolerances of the input specifications of the voltage step-up circuit are relatively wide compared to the tolerances of its output specifications, even if a voltage drop due to the memory effect occurs in the storage battery, the minimum operable voltage of the electronic circuit can be maintained until the output voltage of the storage battery deteriorates to the lower-limit value of the input specifications. As a result, battery life is extended dramatically and the memory effect can be essentially eliminated.
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patent: 4970451 (1990-11-01), Suomalainen
patent: 5652499 (1997-07-01), Morita et al.
patent: 5656876 (1997-08-01), Radley et al.
patent: 5990664 (1999-11-01), Rahman
patent: 0788177 A1 (1977-08-01), None
patent: 9-149631 (1997-06-01), None
Rudolf F. G
Helfgott & Karas P.C.
Sony Computer Entertainment Inc.
Toatley , Jr. Gregory J.
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