# US 7,609,005 B2 · Circuitry for portable lighting devices and portable rechargeable electronic devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,005 B2 - Document ID: US7609005B2 - Status: Granted - Kind: B2 - Application number: 11/517,627 - Filed: 2006-09-07 - Published: 2007-03-22 - Granted: 2009-10-27 - Earliest claimed: 2004-12-07 - Assignees: Mag Instrument, Inc. - Inventors: Stacey H. West - Web page: https://patentgrep.com/patent/US7609005B2 ## CPC - F21L 4/005: {the device being a pocket lamp (F21L4/022, F21L4/045, F21L4/085 take precedence)} - F21V 23/00: Arrangement of electric circuit elements in or on lighting devices {(characterised by cooling arrangements F21V29/508)} - H02J 7/60: including safety or protection arrangements - H02J 7/663: {using battery or load disconnect circuits (H02J9/002 takes precedence)} - H02J 7/855: {with circuits adapted for supplying loads from the battery} - H02J 7/96: in response to battery voltage - F21L: LIGHTING DEVICES OR SYSTEMS THEREOF, BEING PORTABLE OR SPECIALLY ADAPTED FOR TRANSPORTATION - F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY ## Abstract A portable rechargeable electronic device, such as a flashlight, with external charging contacts and a short protection circuit is disclosed. The short protection circuit electrically uncouples one of the exposed charging contacts from the rechargeable power supply for the device when the charging contacts are short circuited. The charging contact is uncoupled without opening the power circuit for the device; thus, the device can continue to operate while the charging contacts are shorted. The power supply for the device may be a rechargeable lithium-ion battery pack. A flashlight with a circuit for reducing the initial surge of current that is sent through the lamp filament when a flashlight is turned on is also provided. The circuit reduces the stresses placed on the lamp bulb when it is turned on, thereby extending the life expectancy of the lamp bulb. A flashlight with an electronic switch is also disclosed. ## Claims ### Claim 1 A rechargeable electronic device comprising: a main power circuit including a DC power source and a power consuming load; a first charging contact electrically coupled to a first electrode of the power source via a first electrical path; a second charging contact electrically coupled to a second electrode of the power source via a second electrical path; and a short protection circuit configured to open the first electrical path at a location that is not within the main power circuit if the first charging contact and the second charging contact are shorted together. ### Claim 2 (depends on 1) The rechargeable electronic device of claim 1, wherein the short protection circuit includes a switch interposed in the first electrical path between the first charging contact and the first electrode at a location that is not within the main power circuit, and wherein the short protection circuit is configured to open the switch if the first and second charging contacts are shorted together. ### Claim 3 (depends on 2) The rechargeable electronic device of claim 2, wherein the short protection circuit includes a comparing device, and the comparing device compares a voltage of a first input signal to a voltage of a second input signal and opens or closes the switch based on the comparison. ### Claim 4 (depends on 3) The rechargeable electronic device of claim 3, wherein the voltage of the first signal is proportional to the voltage drop between the first charging contact and ground and the voltage of the second signal is proportional to the voltage of the power source. ### Claim 5 (depends on 4) The rechargeable electronic device of claim 4, wherein the comparing device signals the switch to open when the voltage of the second signal is greater than or equal to the voltage of the first signal. ### Claim 6 (depends on 5) The rechargeable electronic device of claim 5, wherein the voltage of the first signal is greater than 50% and less than or equal to about 60% of the voltage drop between the first charging contact and ground, and the voltage of the second signal is about 50% of the voltage of the power source. ### Claim 7 (depends on 3) The rechargeable electronic device of claim 3, wherein the comparing device is a voltage comparator. ### Claim 8 (depends on 3) The rechargeable electronic device of claim 3, wherein the comparing device is an ASIC. ### Claim 9 (depends on 3) The rechargeable electronic device of claim 3, wherein the comparing device is a processor. ### Claim 10 (depends on 2) The rechargeable electronic device of claim 2, wherein the switch is a transistor. ### Claim 11 (depends on 2) The rechargeable electronic device of claim 2, wherein the switch is a p-channel MOSFET. ### Claim 12 (depends on 1) The rechargeable electronic device of claim 1, wherein the device is a flashlight. ### Claim 13 (depends on 1) The rechargeable electronic device of claim 1, wherein the DC power source comprises a rechargeable lithium-ion battery pack. ### Claim 14 A rechargeable flashlight comprising: a power source; a lamp electrically coupled to the power source through a main power circuit; a first charging contact electrically coupled to a first electrode of the power source through a first electrical path; a second charging contact electrically coupled to a second electrode of the power source through a second electrical path; and a logic circuit controlling a switch interposed in the first electrical path at a location that is not within the main power circuit, the logic circuit signaling the switch to open if the first and second charging contacts are shorted together. ### Claim 15 (depends on 14) The rechargeable flashlight of claim 14, further comprising a barrel, wherein the barrel contains the power source and the second charging contact comprises at least a portion of the barrel. ### Claim 16 (depends on 14) The rechargeable flashlight of claim 14 wherein the logic circuit includes a comparing device, and the comparing device compares a voltage of a first input signal to a voltage of a second input signal and opens or closes the switch based on the comparison. ### Claim 17 (depends on 16) The rechargeable flashlight of claim 16, wherein the voltage of the first signal is proportional to the voltage drop between the first charging contact and ground and the voltage of the second signal is proportional to the voltage of the power source. ### Claim 18 (depends on 17) The rechargeable flashlight of claim 17, wherein the comparing device signals the switch to open when the voltage of the first signal is less than or equal to the voltage of the second signal. ### Claim 19 (depends on 18) The rechargeable flashlight of claim 18, wherein the voltage of the first signal is greater than 50% and less than or equal to about 60% of the voltage drop between the first charging contact and ground, and the voltage of the second signal is about 50% of the voltage of the power source. ### Claim 20 (depends on 16) The rechargeable flashlight of claim 16, wherein the comparing device comprises a device selected from the group consisting of a voltage comparator, op amp, an ASIC, and a processor. ### Claim 21 (depends on 14) The rechargeable flashlight of claim 14, wherein the switch is a transistor. ### Claim 22 (depends on 14) The rechargeable flashlight of claim 14, wherein the switch is a p-channel MOSFET. ### Claim 23 (depends on 14) The rechargeable flashlight of claim 14, wherein the power source comprises a rechargeable lithium-ion battery pack.