Array of light emitting diodes
OwnerChristopher Lathaminventor
Life of this patent
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Abstract
The invention concerns LED arrays of the type in which one or more “strings” of LEDs such as 6 are series connected across a potential difference as at 8, 10. To compensate for changes in forward voltage of individual LEDs 4, and/or for supply voltage variations, a switching means (which may be formed as a transistor T2, T3) is provided for selectively removing one or more LEDs from the strings. This can for example be done by selectively shorting the chosen LEDs.
Claims17
An array of light emitting diodes (LEDs) comprising at least one string of LEDs within which the LEDs are connected in series with one another to form a current path through the string, the string being connectable across a potential difference to drive the LEDs, the array being provided with an arrangement for controlling forward voltage of the string, comprising at least one switching device connected to the LEDs such that by switching it serves to remove at least one LED from the current path through the string.
A method of controlling the forward voltage of a set of light emitting diodes (LEDs), comprising connecting the diodes in a series string to provide a current path through them, connecting the string of LEDs across a potential difference to cause a current to flow through them, and selectively removing at least one LED from said current path when necessary to reduce the total forward voltage of the string.
Dependencies are inferred from the claim text.