Universal battery charger

Claim 2

A battery charger, comprising: a source of electrical power for providing signals of cyclically varying amplitude; a switching device that is triggerable for coupling at least a portion of the varying amplitude signals to a battery to be charged; a trigger circuit for providing a trigger signal to the switching device; a logical ANDing circuit having at least two inputs for receiving electrical signals corresponding to criteria that must be satisfied before the switching device can be triggered, said logical ANDing circuit having an output for enabling the trigger circuit so that when the trigger criteria is satisfied, the switching device is triggered; and a trigger level detector coupled to one input of said logical ANDing circuit and responsive to a predetermined amplitude of the varying amplitude signal for enabling said ANDing circuit when the varying amplitude signal is below a predefined trigger level.

Claim 3

The battery charger of claim 1, further including a negative slope detector coupled to one input of said logical ANDing circuit and responsive to said varying amplitude signal for enabling said ANDing circuit when a negative slope of said varying amplitude signal occurs.

Claim 4

The battery charger of claim 1, further including a full charge detector coupled to one input of said logical ANDing circuit for enabling when the terminal voltage of said battery is less than a full charge magnitude.

Claim 5

The battery charger of claim 1, further including a battery detector circuit coupled to one input of said logical ANDing circuit for enabling when a battery is physically connected to an output of said charger, and for disabling the ANDing circuit when the output of the battery charger is short circuited.

Claim 6

The battery charger of claim 1, wherein said switching device comprises a silicon controlled rectifier (SCR) having an anode connected to the source of the varying amplitude signals, and a cathode connected to a terminal of the battery, and wherein said trigger circuit triggers the SCR at a predefined magnitude of the varying amplitude signals, whereby battery charging pulses coupled to the battery by the SCR do not vary substantially in amplitude, but vary in pulse width as a function of the terminal voltage of the battery.

Claim 7

The battery charger of claim 1, further including an input AC receptacle for coupling an AC voltage to said switching device, said AC voltage defining said varying amplitude signal, and further including a plurality of AC cords, each having an identical connector at one end, and each having a different electrical connector at the respective opposite end, whereby the battery charger can be utilized with plural different AC distribution systems.

Claim 8

The battery charger of claim 1, further including a negative slope detector circuit producing an output during negative slope time periods of the varying amplitude signal, and wherein said negative slope detector circuit enables said logical ANDing circuit during negative slope time periods of the varying amplitude signals, whereby the signals coupled through said switching device are always equal to or less than said predefined trigger level and occur coincident during negative slope time periods of the varying amplitude signals.

Claim 9

The battery charger of claim 1, further including a battery detector connectable to the battery, said battery detector being coupled to said logical ANDing circuit for enabling thereof, said battery detector including a logic gate having an input so that when a voltage supplied thereto from the battery exceeds a minimum logic one amplitude, the logical ANDing circuit is enabled.

Claim 10

The battery charger of claim 1, further including a negative slope detector responsive to the varying amplitude signal for providing an output indication when the varying amplitude signal is characterized by an negative slope, said negative slope detector comprising a ramp generator having a timing period corresponding to a period of said varying amplitude signal, said ramp generator output being coupled to one input of a comparator, and a reference voltage coupled to a different input of said comparator whereby said comparator provides an enabling output corresponding to a negative slope time period of the varying amplitude signal.

Claim 11

A battery charger, comprising: means for rectifying an AC signal; a switching device that is triggerable for coupling at least a portion of the rectified AC signal to a battery to be charged; a slope detector for providing a first enable signal during at least a portion of a negative slope of the rectified AC signal; a trigger circuit responsive to a predefined trigger level occurring on said rectified waveform for providing a second enable signal; and a combining circuit for combining the first and second enable signals for triggering said switching device at said trigger level and on a negative slope of the AC signal, and said switching device remains conductive so long as the trigger level on the AC signal exceeds a voltage of about that of the battery terminal voltage.

Claim 12

A battery charger, comprising: means for rectifying an AC signal; a switching device that is triggerable for coupling at least a portion of the rectified AC signal to a battery to be charged; a slope detector for providing a first enable signal during at least a portion of a negative slope of the rectified AC signal; a trigger circuit responsive to a predefined trigger level occurring on said rectified waveform for providing a second enable signal; and a combining circuit for combining the first and second enable signals for triggering said switching device at said trigger level and on a negative slope of the AC signal, and said switching device remains conductive so long as the trigger level on the AC signal exceeds a voltage of about that of the battery terminal voltage.

Claim 13

The battery charger of claim 10, wherein said trigger circuit trigger said switching device at a predetermined magnitude, and as said battery terminal voltage increases, the charging pulses passed by said switching device are characterized by smaller pulse widths.

Claim 14

The battery charger of claim 10, further including a detector for enabling said trigger circuit, said detector defined by a comparator having a reference voltage on one input and another voltage representative of the battery terminal voltage on another input, and wherein said reference voltage corresponds to a battery terminal voltage below which the battery requires charging, whereupon said switching device is not triggered unless the battery requires charging.

Claim 15

The battery charger of claim 10, further including multiple outputs for connection to a corresponding multiplicity of batteries, a single trigger circuit for triggering a multiplicity of switching devices, each said switching device switchably coupling a portion of the AC signal to an associated output of the battery charger, and further including a plurality of full charger detection circuits, each for detecting when a respective battery is fully charged.

Claim 16

The battery charger of claim 10, wherein said slope detector is responsive to the rectified AC signal for providing said first enable signal, and said trigger circuit provides said second enable signal defining a time period when the amplitude of the AC signal is less than a predefined threshold amplitude, and said combining circuit includes an ANDing circuit for providing an output trigger signal having a pulse width about equal to a time period in which the first and second enable signals are coincident in time.

Claim 19

The method of claim 15, further including detecting whether a battery having a minimum voltage is connected to a pair of output terminals, and if such a battery is connected to the output terminals, enabling triggering of the switching device, and if the pair of output terminals are short circuited together, preventing triggering of the switching device.

Claim 20

The method of claim 16, further including detecting said connection of the battery by associating a minimum battery terminal voltage with a logic level of a logic gate, and providing a predetermined output of the logic gate when a battery with at least said minimum battery terminal voltage is connected to the output terminals.

Claim 21

The method of claim 15, further including sensing the presence of; 1) a predetermined amplitude of said rectified AC signal; 2) a negative slope of the rectified AC signal; 3) the presence of a battery connected for charging; 4) an indication that the battery requires charging; and triggering the switching device on the presence of steps 1)-4).

Claim 22

A battery charger, comprising: a rectifier for converting AC signals into rectified signals; a switching device that is triggerable to couple at least portions of the rectified signals to a battery to be charged; a logical ANDing circuit having plural inputs, and an output for enabling the switching device to be triggered; a trigger level detector for sensing the rectified signal and providing an output when the instantaneous voltage of the rectified signal is below a specified level, said trigger level detector output being coupled to an input of said logical ANDing circuit; a negative slope detector producing an output during a time period of a negative slope portion of the rectified signal, said negative slope detector output being coupled to an input of said logical ANDing circuit; a full charge detector circuit responsive to the battery terminal voltage for providing an output to an input of said logical ANDing circuit when said battery terminal voltage is below a specified voltage; and a battery detector circuit responsive to the connection of a battery to the battery charger, for providing an output to an input of said logical ANDing circuit; and whereby said logical ANDing circuit is responsive to the inputs thereof for enabling said switching device to be triggered.

Claim 23

A battery charger, comprising: a rectifier for converting AC signals into rectified signals; a switching device that is triggerable to couple at least portions of the rectified signals to a battery to be charged; a logical ANDing circuit having plural inputs, and an output for enabling the switching device to be triggered; a trigger level detector for sensing the rectified signal and providing an output when the instantaneous voltage of the rectified signal is below a specified level, said trigger level detector output being coupled to an input of said logical ANDing circuit; a negative slope detector producing an output during a time period of a negative slope portion of the rectified signal, said negative slope detector output being coupled to an input of said logical ANDing circuit; a full charge detector circuit responsive to the battery terminal voltage for providing an output to an input of said logical ANDing circuit when said battery terminal voltage is below a specified voltage; and a battery detector circuit responsive to the connection of a battery to the battery charger, for providing an output to an input of said logical ANDing circuit; and whereby said logical ANDing circuit is responsive to the inputs thereof for enabling said switching device to be triggered.

Claim 24

The battery charger of claim 19, further including plural switching devices each associated with a different output of said battery charger, and each associated with a different full charge detector and battery detector, and each associated with a common trigger level detector and negative slope detector.

Claim 25

The battery charger of claim 19, wherein said ANDing circuit comprises two AND gates, each having plural inputs, and one AND gate having an output connected to an input of the other AND gate.

Claim 26

The battery charger of claim 19, wherein said battery detector circuit is responsive to a minimum battery terminal voltage to enable said ANDing circuit, and disables said ANDing circuit when the battery terminal voltage is below said minimum.

Claim 27

The battery charger of claim 22, further including a pair of output terminals to which a battery is connectable, and wherein said battery detector circuit disables said ANDing circuit when the pair of output terminals are short circuited together.