1. A method for driving an LED lighting device, comprising:
receiving an input voltage from a battery unit;
converting the input voltage into a driving current to drive the LED lighting device;
detecting whether the battery unit is in a low battery state; and
reducing the driving current when the low battery state of the battery unit is detected, wherein the driving current is reduced in a plurality of steps, and the driving current is reduced by a preset value during each of the plurality of steps.
2. The method of claim 1, wherein the step of detecting whether the battery unit is in a low battery state comprises detecting whether the input voltage reaches a predetermined voltage level.
3. The method of claim 2, wherein the driving current is reduced by a next step of the plurality of steps only when the input voltage reaches the predetermined voltage level.
4. The method of claim 3, wherein during each of the plurality of steps, the driving current is reduced by the preset value and is then maintained until the next step of the plurality of steps.
5. The method of claim 1, wherein the LED lighting device is a flashlight or a headlamp.
6. A controller coupled to a power converter, wherein the power converter is configured to receive an input voltage from a battery unit and to provide a driving current to an LED lighting device, wherein the controller comprises:
a detecting circuit configured to detect a low battery state of the battery unit and to generate an indication signal based on the detection; and
a controlling circuit configured to receive the indication signal and to provide one or more control signals to the power converter to regulate the driving current based on the indication signal;
wherein the driving current is reduced when the low battery state of the battery unit is detected, wherein the driving current is reduced in a plurality of steps, and the driving current is reduced by a preset value during each of the plurality of steps.
7. The controller of claim 6, wherein the controlling circuit comprises:
a reference generator configured to receive the indication signal and to generate a reference signal based on the indication signal;
an error amplifier having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the reference generator to receive the reference signal, the second input terminal is configured to receive a feedback signal indicating the current flowing through the LED lighting device, and wherein the error amplifier amplifies the difference between the reference signal and the feedback signal, and generates an error signal at the output terminal;
a comparator having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the error amplifier to receive the error signal, the second input terminal is configured to receive a current sensing signal, the comparator compares the reference signal with the current sensing signal and generates a comparison signal;
a clock generator configured to generate a clock signal; and
a logic circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the comparator to receive the comparison signal, the second terminal is coupled to the clock generator to receive the clock signal, wherein the logic circuit generates the one or more control signals based on the comparison signal and the clock signal.
8. The controller of claim 6, wherein the detecting circuit comprises a comparator having a first input terminal, a second input terminal and an output terminal, and wherein the first input terminal is configured to receive the input voltage, the second input terminal is configured to receive a predetermined voltage level, the comparator compares the input voltage with the predetermined voltage level and generates the indication signal at the output terminal.
9. The controller of claim 8, wherein the driving current is reduced by a next step of the plurality of steps only when the input voltage reaches the predetermined voltage level.
10. The controller of claim 9, wherein during each of the plurality of steps, the driving current is reduced by the preset value and is then maintained until the next step of the plurality of steps.
11. A circuit for driving an LED lighting device, comprising:
a power converter configured to receive an input voltage from a battery unit and to provide a driving current to the LED lighting device;
a detecting circuit configured to detect a low battery state of the battery unit and to generate an indication signal based on the detection; and
a controlling circuit configured to receive the indication signal and to provide one or more control signals to the power converter to regulate the driving current based on the indication signal;
wherein the driving current is reduced when the low battery state of the battery unit is detected, and wherein the controlling circuit comprises:
a reference generator configured to receive the indication signal and to generate a reference signal based on the indication signal;
an error amplifier having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the reference generator to receive the reference signal, the second input terminal is configured to receive a feedback signal indicating the current flowing through the LED lighting device, and wherein the error amplifier amplifies the difference between the reference signal and the feedback signal, and generates an error signal at the output terminal;
a comparator having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the error amplifier to receive the error signal, the second input terminal is configured to receive a current sensing signal, the comparator compares the reference signal with the current sensing signal and generates a comparison signal;
a clock generator configured to generate a clock signal; and
a logic circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the comparator to receive the comparison signal, the second terminal is coupled to the clock generator to receive the clock signal, wherein the logic circuit generates the one or more control signals based on the comparison signal and the clock signal.
12. The circuit of claim 11, wherein the detecting circuit comprises a comparator having a first input terminal, a second input terminal and an output terminal, and wherein the first input terminal is configured to receive the input voltage, the second input terminal is configured to receive a predetermined voltage level, the comparator compares the input voltage with the predetermined voltage level and generates the indication signal at the output terminal.
13. The circuit of claim 12, wherein the driving current is reduced in a plurality of steps, and wherein the driving current is reduced by a preset value during each of the plurality of steps, and the driving current is reduced by a next step of the plurality of steps only when the input voltage reaches the predetermined voltage level.
14. The circuit of claim 13, wherein during each of the plurality of steps, the driving current is reduced by the preset value and is then maintained until the next step of the plurality of steps.
15. The circuit of claim 11, wherein the driving current is reduced to a first current level when the low battery state of the battery unit is detected, and the driving current is maintained at the first current level until the battery unit dies.
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 method, comprising:
providing a plurality of products that are each associated with a respective radio frequency identification tag;
using radio frequency identification technology to automatically identify specific products within a group of the products collected by a shopper; and
evaluating whether to obtain payment from the shopper based on the radio frequency identification of products in the group and then, based on the result of the evaluating, carrying out one of:
obtaining payment from the shopper based on the radio frequency identification of products in the group; and
auditing the products in the group, and then obtaining payment from the shopper based on the products identified by the auditing.
2. A method according to claim 1,
including maintaining a business value that is selectively adjustable by the seller; and
carrying out the evaluating as a function of the business value.
3. A method according to claim 2,
including assigning each of the plurality of products a respective difficulty rating representing the level of difficulty involved in identifying that product using radio frequency identification technology;
wherein the evaluating includes selecting one of a plurality of different difficulty thresholds as a function of the business value; and
carrying out the auditing and the obtaining of payment based on the auditing if any of the products identified by radio frequency identification technology has a difficulty rating in excess of the selected difficulty threshold.
4. A method according to claim 2,
wherein the evaluating includes selecting one of a plurality of different tag count thresholds as a function of the business value; and
carrying out the auditing and the obtaining of payment based on the auditing if the number of tags detected with radio frequency identification technology is in excess of the selected tag count threshold.
5. A method according to claim 2,
wherein the group of products collected by the shopper is in a shopping container;
including measuring the weight of the container and the products therein;
wherein the evaluating includes subtracting the tare weight of the container from the measured weight of the container and products therein in order to obtain the measured weight of the products, and selecting one of a plurality of different weight thresholds as a function of the business value; and
carrying out the auditing and the obtaining of payment based on the auditing if the measured weight of the products is in excess of the selected weight threshold.
6. A method according to claim 2,
wherein the group of products collected by the shopper is in a shopping container;
including measuring the weight of the container and the products therein; wherein the evaluating includes subtracting the tare weight of the container from the measured weight of the container and products therein in order to obtain the measured weight of the products, and selecting one of a plurality of different ranges as a function of the business value, each range corresponding to a respective different relationship between weight and number of tags; and
carrying out the auditing and the obtaining of payment based on the auditing if the measured weight of the products and the number of tags detected with radio frequency identification technology are not both within the selected range.
7. A method according to claim 2,
wherein the group of products collected by the shopper is in a shopping container;
including measuring the weight of the container and the products therein;
wherein the evaluating includes subtracting the tare weight of the container from the measured weight of the container and products therein in order to obtain the measured weight of the products, determining a calculated product weight based on the set of products identified with radio frequency identification technology, calculating a weight differential between the measured product weight and the calculated product weight, and selecting one of a plurality of different differential thresholds as a function of the business value; and
carrying out the auditing and the obtaining of payment based on the auditing if the weight differential is greater than the selected differential threshold.
8. A method according to claim 1,
including using a further technology different from radio frequency identification technology to automatically identify specific products within the group of products collected by the shopper;
wherein the evaluating includes comparing the number of products identified with radio frequency identification technology to the number of products identified with the further technology; and
carrying out the auditing and the obtaining of payment based on the auditing if the comparison indicates that the number of products identified with radio frequency identification technology is different from the number of products identified with the further technology.
9. A method according to claim 1,
wherein the evaluating includes: determining a plurality of different confidence levels that are each a function of the group of products collected by the shopper; and
determining the result of the evaluating as a function of each of the different confidence levels.
10. A method according to claim 9,
including maintaining a threshold value that is selectively adjustable by the seller;
including maintaining a plurality of weight values that are each associated with a respective one of the confidence levels, and that are each selectively adjustable by the seller;
wherein the determining of the result of the evaluating includes calculating a sum of the confidence levels each multiplied by the associated weight value, dividing the resulting sum by a sum of the weight values to determine a confidence value, and comparing the confidence value to the threshold value; and
carrying out the auditing and the obtaining of payment based on the auditing if the confidence value is less than the threshold value.
11. A method according to claim 9,
including assigning each of the plurality of products a respective difficulty rating representing the level of difficulty involved in identifying that product using radio frequency identification technology; and
wherein the determining of confidence levels includes determining one of the confidence levels by calculating an average of the difficulty rating of all products within the group detected using radio frequency identification technology.
12. A method according to claim 9,
including maintaining a set of different confidence levels that each correspond to a respective different number of tags; and
wherein the determining of confidence levels includes determining one of the confidence levels by taking the number of tags detected with radio frequency identification technology and identifying a corresponding one of the confidence levels from the set.
13. A method according to claim 9,
including maintaining a set of different confidence levels that each correspond to a respective different weight; wherein the group of products collected by the shopper is in a shopping container;
including measuring the weight of the container and the products therein;
wherein the evaluating includes subtracting the tare weight of the container from the measured weight of the container and products therein in order to obtain the measured weight of the products; and
wherein the determining of confidence levels includes determining one of the confidence levels by taking the measured weight of the products and identifying the corresponding one of the confidence levels from the set.
14. A method according to claim 9,
including maintaining a set of different confidence levels that each correspond to a respective different relationship between weight and number of tags;
wherein the group of products collected by the shopper is in a shopping container;
including measuring the weight of the container and the products therein;
wherein the evaluating includes subtracting the tare weight of the container from the measured weight of the container and products therein in order to obtain the measured weight of the products; and
wherein the determining of confidence levels includes determining one of the confidence levels by taking the measured weight of the products and the number of tags detected with radio frequency identification technology, and identifying a corresponding one of the confidence levels from the set.
15. A method according to claim 9,
including maintaining a set of different confidence levels that each correspond to a respective weight differential;
wherein the group of products collected by the shopper is in a shopping container;
including measuring the weight of the container and the products therein;
wherein the evaluating includes subtracting the tare weight of the container from the measured weight of the container and products therein in order to obtain the measured weight of the products, determining a calculated product weight based on the set of products identified with radio frequency identification technology, and calculating a weight differential between the measured product weight and the calculated product weight; and
wherein the determining of confidence levels includes determining one of the confidence levels by taking the calculated weight differential and identifying a corresponding one of the confidence levels from the set.
16. A method according to claim 9,
including using a further technology different from radio frequency identification technology to automatically identify specific products within the group of the products collected by the shopper; and
wherein the determining of confidence levels includes determining one of the confidence levels by assigning it a high level of confidence if the number of products identified with radio frequency identification technology equals the number of products identified with the further technology, and assigning it a low level of confidence if the number of products identified with radio frequency identification technology is different from the number of products identified with the further technology.
17. An apparatus, comprising:
a radio frequency identification section that uses radio frequency identification technology to automatically identify specific products within a group of products collected by a shopper from a plurality of products that are each associated with a respective radio frequency identification tag;
an evaluating section that evaluates whether to obtain payment from the shopper based on the radio frequency identification of products in the group and then, based on the result of the evaluation, calls for one of:
obtaining payment from the shopper based on the radio frequency identification of products in the group; and
auditing of the products in the group, followed by obtaining payment from the shopper based on the products identified by the auditing.
18. An apparatus according to claim 17,
wherein the group of products collected by the shopper is in a shopping container;
including a weight measuring section that measures the weight of the container and the products therein; and
wherein the evaluating section subtracts the tare weight of the container from the measured weight of the container and products therein in order to obtain the measured weight of the products, and thereafter carries out the evaluation of how to obtain payment from the shopper as a function of the measured weight of the products.
19. An apparatus according to claim 17,
including a further section that uses a further technology different from radio frequency identification technology to automatically identify specific products within the group of products collected by the shopper; and
wherein the evaluating section carries out the evaluation of how to obtain payment from the shopper as a function of the products identified using the further technology.
20. An apparatus according to claim 17, including first and second point-of-sale terminals that are each operatively coupled to the evaluating section, the first point-of-sale terminal being used for the obtaining of payment from the shopper based on the radio frequency identification of products in the group, and the second point-of-sale terminal being used for the auditing of the products in the group, and the obtaining payment from the shopper based on the products identified by the auditing.