EP-4736581-A1 - LIGHT-EMITTING DIODE PACKAGES WITH VARYING CURRENT PULSE WIDTH MODULATION AND RELATED METHODS

Abstract

Light-emitting diode (LED) packages and, more particularly, LED packages with varying current pulse width modulation (PWM) signals and related methods are disclosed. Varying current PWM is provided by having multiple current sources at different current levels for each LED chip in an LED package. An output PWM signal for each LED chip is routed to selectively turn on and off different combinations of current sources to provide varying current levels associated with varying brightness levels for each LED chip. By providing multiple current sources for each LED chip, the dynamic range of current levels and corresponding brightness levels may be increased for a same PWM clock frequency.

Inventors

• HUSSELL, CHRISTOPHER P.

Assignees

• Creeled, Inc.

Dates

Publication Date

20260506

Application Date

20240826

Claims (20)

1. 1 . A light-emitting diode (LED) package configured for receiving and transmitting digital communication signals, the LED package comprising: an LED chip; and an LED driver configured to drive the LED chip by pulse width modulation (PWM), the LED driver comprising a plurality of current sources configured to provide varying current levels to the LED chip.
2. 2. The LED package of claim 1 , wherein at least two current sources of the plurality of current sources are configured to provide different current levels to the LED chip.
3. 3. The LED package of claim 1 , wherein at least two current sources of the plurality of current sources are configured to provide a same current level to the LED chip.
4. 4. The LED package of claim 1 , wherein the varying current levels comprise at least a first current level, a second current level that is greater than the first current level, and a third current level that is greater than the second current level.
5. 5. The LED package of claim 1 , wherein the plurality of current sources is configured to receive an output PWM signal that selects one or more current sources of the plurality of current sources for providing current to the LED chip.
6. 6. The LED package of claim 1 , wherein each current source of the plurality of current sources comprises a switch coupled to the LED chip and to a different output of the output PWM signal.
7. 7. The LED package of claim 1 , wherein the LED driver is configured to adjust the current level provided to the LED chip during less than half of a PWM period.
8. 8. The LED package of claim 7, wherein the LED driver is configured to only adjust the current level provided to the LED chip during a single clock cycle of the PWM period.
9. 9. The LED package of claim 8, wherein the single clock cycle is positioned at a start of the PWM period.
10. 10. The LED package of claim 8, wherein for at least some current levels, the single clock cycle is positioned immediately following another clock cycle of the PWM period where the LED chip is turned on.
11. 1 1 . The LED package of claim 1 , wherein for a particular current level, the LED driver is configured to turn on a unique combination of one or more current sources of the plurality of current sources as compared to a next-closest current level.
12. 12. The LED package of claim 1 , further comprising: an additional LED chip; and an additional LED driver configured to drive the additional LED chip by PWM, the additional LED driver comprising a plurality of additional current sources configured to provide varying current levels to the second LED chip.
13. 13. A method of light output control within a light-emitting diode (LED) package, the method comprising: controlling brightness levels of an LED chip with pulse width modulation (PWM); and adjusting current levels to the LED chip during less than half of a PWM period.
14. 14. The method of claim 13, wherein the current levels are only adjusted for a single clock cycle of the PWM period.
15. 15. The method of claim 14, wherein the single clock cycle is positioned at a start of the PWM period.
16. 16. The method of claim 14, wherein for at least some brightness levels, the single clock cycle is positioned immediately following another clock cycle of the PWM period where the LED chip is turned on.
17. 17. The method of claim 14, wherein the current levels are either at a constant level or off for the remainder of the PWM period.
18. 18. The method of claim 13, wherein adjusting current levels to the LED chip comprises turning on and off different current sources of a plurality of current sources connected to the LED chip.
19. 19. The method of claim 18, wherein at least two current sources of the plurality of current sources provide different current levels to the LED chip.
20. 20. The method of claim 18, wherein at least two current sources of the plurality of current sources provide a same current level to the LED chip.

Description

LIGHT-EMITTING DIODE PACKAGES WITH VARYING CURRENT PULSE WIDTH MODULATION AND RELATED METHODS Field of the Disclosure [0001] The present disclosure relates to light-emitting diode (LED) packages and, more particularly, to LED packages with varying current pulse width modulation signals and related methods. Background [0002] Light-emitting diodes (LEDs) are solid-state devices that convert electrical energy to light and generally include one or more active layers of semiconductor material (or an active region) arranged between oppositely doped n-type and p-type layers. When a bias is applied across the doped layers, holes and electrons are injected into the one or more active layers where they recombine to generate emissions such as visible light or ultraviolet emissions. [0003] LEDs have been widely adopted in various illumination contexts, for backlighting of liquid crystal display (LCD) systems (e.g., as a substitute for cold cathode fluorescent lamps) and for direct-view LED displays. Applications utilizing LED arrays include vehicular headlamps, roadway illumination, light fixtures, and various indoor, outdoor, and specialty contexts. Desirable characteristics of LED devices include high luminous efficacy and long lifetime. [0004] Large format multi-color direct-view LED displays (including full color LED video screens) typically include numerous individual LED panels, packages, and/or components providing image resolution determined by the distance between adjacent pixels or "pixel pitch." Direct-view LED displays typically include three-color displays with arrayed red, green, and blue (RGB) LEDs, and two-color displays with arrayed red and green (RG) LEDs. Other colors and combinations of colors may be used. For many LED display systems, it is desirable to form LED color groups for each pixel such as primary colors red, green, and blue (RGB) that define vertices of a triangle (or polygon) on a chromaticity diagram. This polygon defines the so-called color gamut of the display device, the area of which describes all the possible colors that the display device is capable of producing. Driver printed circuit boards for controlling LED displays are typically densely populated with electrical devices including capacitors, field effect transistors (FETs), decoders, microcontrollers, and the like for driving the pixels of the display. As pixel pitches continue to decrease for higher resolution displays, the density of such electrical devices scales higher corresponding to the increased number of pixels for a given panel area. This tends to add higher complexity and costs to LED panels for display applications. [0005] The art continues to seek improved LED array devices with small pixel pitches while overcoming limitations associated with conventional devices and production methods. [0006] The present disclosure relates to light-emitting diode (LED) packages and, more particularly, to LED packages with varying current pulse width modulation (PWM) signals and related methods. Varying current PWM is provided by having multiple current sources at different current levels for each LED chip in an LED package. An output PWM signal for each LED chip is routed to selectively turn on and off different combinations of current sources to provide varying current levels associated with varying brightness levels for each LED chip. By providing multiple current sources for each LED chip, the dynamic range of current levels and corresponding brightness levels may be increased for a same PWM clock frequency. [0007] In one aspect, an LED package comprises: an LED chip; and an LED driver configured to drive the LED chip by pulse width modulation (PWM), the LED driver comprising a plurality of current sources configured to provide varying current levels to the LED chip. In certain embodiments, at least two current sources of the plurality of current sources are configured to provide different current levels to the LED chip. In certain embodiments, at least two current sources of the plurality of current sources are configured to provide a same current level to the LED chip. In certain embodiments, the varying current levels comprise at least a first current level, a second current level that is greater than the first current level, and a third current level that is greater than the second current level. In certain embodiments, the plurality of current sources is configured to receive an output PWM signal that selects one or more current sources of the plurality of current sources for providing current to the LED chip. In certain embodiments, each current source of the plurality of current sources comprises a switch coupled to the LED chip and to a different output of the output PWM signal. In certain embodiments, the LED driver is configured to adjust the current level provided to the LED chip during less than half of a PWM period. In certain embodiments, the LED driver is configured to only adjust the current level provide