(19) STATE INTELLECTUAL PROPERTY OFFICE OF THE P.R.C.
`(12)
`INVENTION PATENT
`APPLICATION
`(10) APPLICATION PUBLICATION NUMBER: CN 101719345 A
`(43) APPLICATION PUBLICATION DATE: 02 JUNE 2010
`
`1111111111111111111111111111111111111
`
`(21) APPLICATION NO.: 200810169679. 1
`
`(22) APPLICATION DATE: 09 OCTOBER 2008
`
`(71) APPLICANT: RICHTEK TECHNOLOGY CORP
`
`ADDRESS: FLOOR 5, NO. 20, TAIYUAN STREET,
`JHUBEI CITY, HSINCHU COUNTY, TAIWAN,
`CHINA
`
`(72) INVENTOR: SHUIMU LIN, DIDI LIU AND
`HUANZHEN YANG
`
`(74) PATENT AGENCY: SHANGHAI TIANXIE
`HECHENG INTELLECTUAL PROPERTY AGENCY
`FIRM 31216
`
`AGENT: HENGKANG ZHANG
`
`(51)
`
`Int. Cl.
`
`G09G 3/14 (2006. 01)
`
`G09G 3/32 (2006. 01)
`
`CLAIMS 14 PAGES DESCRIPTION 23 PAGES DRAWINGS 13
`
`PAGES
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`
`(54) Title of Invention
`LED Display System and Control Method Thereof
`as well as Driver of LED Display System and
`Control Method Thereof
`(57) Abstract
`The invention relates to an LED display system and
`a control method thereof, as well as a driver of the
`LED display system and a control method thereof.
`The LED display system comprises a plurality of
`LEDs, a plurality of drivers and a power converter,
`wherein the plurality of LEDs are arranged in the
`display system; the plurality of drivers are used for
`driving the plurality of LEDs, each of the drivers is
`provided with a plurality of LED pins, the plurality
`of LEDs are each electrically connected to one of
`the plurality of LEDs, and each of the drivers
`outputs a feedback signal at a feedback signal node;
`and the power converter is arranged in the display
`system and used for receiving a direct current high
`voltage, converting the direct current high voltage
`into at least one direct current low voltage to the
`plurality of LEDs, and adjusting the at least one
`direct current low voltage according to one of the
`plurality of feedback signals.
`
`CN 101719345 A
`
`Samsung Exhibit 1025
`Samsung Elecs. Co., Ltd. v. Ultravision Techns., LLC
`IPR2020-01176
`Page 00001
`
`

`

`CN 101719345 A
`
`What is claimed is:
`
`Claims
`
`
`
`1/14
`
`1. An LED display system, comprisig a plurality of LEDs, a plurality of drivers
`
`and a power converter, wherein:
`
`the plurality of LEDs are arranged in the display system;
`
`the plurality of drivers are used for driving the plurality of LEDs, each of the
`
`drivers is provided with a plurality of LED pins, the plurality of LEDs are each
`
`electrically connected to one of the plurality of LEDs, and each of the drivers
`
`outputs a feedback signal at a feedback signal node; and
`
`the power converter is arranged in the display system and used for receiving a
`
`direct current high voltage, converting the direct current high voltage into at
`
`least one direct current low voltage to the plurality of LEDs, and adjusting the at
`
`least one direct current low voltage according to one of the plurality of feedback
`
`signals.
`
`2.
`
`The LED display system according to claim 1, wherein the LED display system
`
`further comprises a second power converter converting an alternating current
`
`voltage into the direct current high voltage.
`
`3.
`
`The LED display system according to claim 1, wherein the power converter
`
`receives the direct current high voltage, converts the direct current high voltage
`
`into two types of direct current low voltage and supplies them to different LEDs
`
`respectively.
`
`4.
`
`The LED display system according to claim 1, wherein each of the drivers
`
`further comprises:
`
`a minimum voltage selector, selecting a minimum value from among voltages
`
`on the plurality of LED pins; and
`
`a gain circuit, generating the feedback signal according to the minimum value.
`
`5.
`
`The LED display system according to claim 4, wherein the gain circuit
`
`comprises a compensating circuit used for compensating on an error of the
`
`feedback signal arising from temperature.
`
`6.
`
`The LED display system according to claim 4, wherein the gain circuit
`
`2
`
`IPR2020-01176 Page 00002
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`

`

`CN 101719345 A
`
`Claims
`
`
`
`2/14
`
`comprises a controller used for controlling the gain of the gain circuit.
`
`7.
`
`The LED display system according to claim 1, wherein each of the drivers
`
`further comprises a plurality of current sources, each of which controls the
`
`current on one of the plurality of LEDs respectively.
`
`8.
`
`The LED display system according to claim 7, wherein each of the plurality of
`
`current sources comprises:
`
`a resistor;
`
`a transistor, connected between one of the plurality of LED pins and the resistor;
`
`and
`
`an operational amplifier, provided with a first input connected to a voltage end,
`
`a second input connected to a node between the resistor and the transistor, and
`
`an output connected to a gate of the transistor.
`
`9.
`
`The LED display system according to claim 8, wherein each of the drivers
`
`further comprises:
`
`a maximum voltage selector, selecting a maximum value from among gate
`
`voltages of the transistors of the plurality of current sources; and
`
`a gain circuit, generating the feedback signal according to the maximum value.
`
`10. The LED display system according to claim 9, wherein the gain circuit
`
`comprises a controller used for controlling the gain of the gain circuit.
`
`11. The LED display system according to claim 1, wherein each of the drivers
`
`further comprises:
`
`a minimum voltage selector, selecting a minimum value from among voltages
`
`on the plurality of LED pins;
`
`a gain circuit, generating a direct current signal according to the minimum
`
`value;
`
`a current source, used for providing a current to the feedback signal node;
`
`a switch, connected between the feedback signal node and a ground terminal;
`
`and
`
`3
`
`IPR2020-01176 Page 00003
`
`

`

`CN 101719345 A
`
`Claims
`
`
`
`3/14
`
`a switching circuit, generating a pulse width modulation signal according to the
`
`direct current signal and the voltage on the feedback signal node to toggle the
`
`switch to adjust the feedback signal.
`
`12. The LED display system according to claim 11, wherein the gain circuit
`
`comprises a compensating circuit used for compensating on an error of the
`
`feedback signal arising from temperature.
`
`13. The LED display system according to claim 11, wherein the gain circuit
`
`comprises a controller used for controlling the gain of the gain circuit.
`
`14. The LED display system according to claim 1, wherein each of the drivers
`
`further comprises:
`
`a minimum voltage sampler, sampling and outputting a minimum value from
`
`among voltages on the plurality of LED pins; and
`
`a gain circuit, generating the feedback signal according to the minimum value.
`
`15. The LED display system according to claim 14, wherein the gain circuit
`
`comprises a compensating circuit used for compensating on an error of the
`
`feedback signal arising from temperature.
`
`16. The LED display system according to claim 14, wherein the gain circuit
`
`comprises a controller used for controlling the gain of the gain circuit.
`
`17. The LED display system according to claim 14, wherein the power converter
`
`comprises:
`
`a first comparator, comparing the feedback signal and a first reference voltage
`
`to generate a first comparison signal;
`
`a second comparator, comparing the feedback signal and a second reference
`
`voltage to generate a second comparison signal;
`
`a logic circuit, generating a digital signal according to the first and second
`
`comparison signals;
`
`a digital analogue converter, converting the digital signal into an analogue
`
`signal; and
`
`an error amplifier, generating a control signal according to the analogue signal
`
`4
`
`IPR2020-01176 Page 00004
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`

`

`CN 101719345 A
`
`Claims
`
`
`
`4/14
`
`and a third reference voltage to adjust the low voltage.
`
`18. An LED display system, comprising a plurality of LEDs, a power converter and
`
`a plurality of drivers, wherein:
`
`the plurality of LEDs are arranged in the display system;
`
`the power converter is used for converting a direct current high voltage into at
`
`least one direct current low voltage to the plurality of LEDs;
`
`the plurality of drivers are used for driving the plurality of LEDs, each of the
`
`drivers is provided with a plurality of LED pins each electrically connected to
`
`one of the plurality of LEDs; and
`
`each of the drivers receives a first digital signal, and outputs a second digital
`
`signal as a first digital signal of next driver, while a second output digital signal
`
`output by the last driver is used for adjusting the at least one direct current low
`
`voltage.
`
`19. The LED display system according to claim 18, wherein the LED display
`
`system further comprises a second power converter converting an alternating
`
`current voltage into the direct current high voltage.
`
`20. The LED display system according to claim 18, wherein each of the drivers
`
`further comprises:
`
`a minimum voltage sampler, sampling and outputting a minimum value from
`
`among voltages on the plurality of LED pins;
`
`a gain circuit, generating a first signal according to the minimum value;
`
`a first comparator, comparing the first signal and a first reference voltage to
`
`generate a second signal;
`
`a second comparator, comparing the first signal and a second reference voltage
`
`to generate a third signal; and
`
`a logic circuit, generating a second digital signal according to the second signal,
`
`the third signal and the first digital signal.
`
`21. The LED display system according to claim 20, wherein the gain circuit
`
`comprises a compensating circuit used for compensating on an error of the
`
`5
`
`IPR2020-01176 Page 00005
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`

`

`CN 101719345 A
`
`Claims
`
`
`
`5/14
`
`second digital signal arising from temperature.
`
`22. The LED display system according to claim 20, wherein the gain circuit
`
`comprises a controller used for controlling the gain of the gain circuit.
`
`23. A driver of an LED display system, the LED display system comprising a power
`
`converter used for providing an output voltage to a plurality of LEDs, the driver
`
`comprising a plurality of LED pins, a feedback signal node, a minimum voltage
`
`selector and a gain circuit, wherein:
`
`the plurality of LEDs are each electrically connected to one of the plurality of
`
`LEDs;
`
`the feedback signal node outputs a feedback signal to the power converter to
`
`adjust the output voltage;
`
`the minimum voltage selector selects a minimum value from among voltages on
`
`the plurality of LED pins; and
`
`the gain circuit generates the feedback signal according to the minimum value.
`
`24. The driver according to claim 23, wherein the gain circuit comprises a
`
`compensating circuit used for compensating on an error of the feedback signal
`
`arising from temperature.
`
`25. The driver according to claim 23, wherein the gain circuit comprises a controller
`
`used for controlling the gain of the gain circuit.
`
`26. A driver of an LED display system, the LED display system comprising a power
`
`converter used for providing an output voltage to a plurality of LEDs, the driver
`
`comprising a plurality of LED pins, a feedback signal node, a plurality of
`
`current sources, a maximum voltage selector and a gain circuit, wherein:
`
`the plurality of LEDs are each electrically connected to one of the plurality of
`
`LEDs;
`
`the feedback signal node outputs a feedback signal to the power converter to
`
`adjust the output voltage;
`
`the plurality of current sources each control the current on one of the plurality of
`
`LEDs, and each of the plurality of current sources comprises:
`
`6
`
`IPR2020-01176 Page 00006
`
`

`

`CN 101719345 A
`
`a resistor;
`
`Claims
`
`
`
`6/14
`
`a transistor, electrically connected between one of the plurality of LED pins and
`
`the resistor; and
`
`an operational amplifier, provided with a first input electrically connected to a
`
`voltage end, a second input electrically connected to a node between the resistor
`
`and the transistor, and an output electrically connected to a gate of the transistor;
`
`the maximum voltage selector selects a maximum value from among voltages
`
`on transistor gates of the plurality of current sources; and
`
`the gain circuit generates the feedback signal according to the maximum value.
`
`27. The driver according to claim 26, wherein the gain circuit comprises a controller
`
`used for controlling the gain of the gain circuit.
`
`28. A driver of an LED display system, the LED display system comprising a power
`
`converter used for providing an output voltage to a plurality of LEDs, the driver
`
`comprising a plurality of LED pins, a feedback signal node, a minimum voltage
`
`selector, a gain circuit, a current source, a switch and a switching circuit,
`
`wherein:
`
`the plurality of LEDs are each electrically connected to one of the plurality of
`
`LEDs;
`
`the feedback signal node outputs a feedback signal to the power converter to
`
`adjust the output voltage;
`
`the minimum voltage selector selects a minimum value from among voltages on
`
`the plurality of LED pins;
`
`the gain circuit generates a direct current signal according to the minimum
`
`value;
`
`the current source is used for providing a current to the feedback signal node;
`
`the switch is electrically connected between the feedback signal node and a
`
`ground terminal; and
`
`the switching circuit generates a pulse width modulation signal according to the
`
`direct current signal and the feedback signal to toggle the switch to adjust the
`
`7
`
`IPR2020-01176 Page 00007
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`

`

`CN 101719345 A
`
`Claims
`
`
`
`7/14
`
`feedback signal.
`
`29. The driver according to claim 28, wherein the gain circuit comprises a
`
`compensating circuit used for compensating on an error of the feedback signal
`
`arising from temperature.
`
`30. The driver according to claim 28, wherein the gain circuit comprises a controller
`
`used for controlling the gain of the gain circuit.
`
`31. A driver of an LED display system, the LED display system comprising a power
`
`converter used for providing an output voltage to a plurality of LEDs, the driver
`
`comprising a plurality of LED pins, a feedback signal node, a minimum voltage
`
`sampler and a gain circuit, wherein:
`
`the plurality of LED pins are each electrically connected to one of the plurality
`
`of LEDs;
`
`the feedback signal node outputs a feedback signal to the power converter to
`
`adjust the output voltage;
`
`the minimum voltage sampler samples and outputs a minimum value from
`
`among voltages on the plurality of LED pins; and
`
`the gain circuit generates the feedback signal according to the minimum value.
`
`32. The driver according to claim 31, wherein the gain circuit comprises a
`
`compensating circuit used for compensating on an error of the feedback signal
`
`arising from temperature.
`
`33. The driver according to claim 31, wherein the gain circuit comprises a
`
`controller used for controlling the gain of the gain circuit.
`
`34. A driver of an LED display system, the LED display system comprising a power
`
`converter used for providing an output voltage to a plurality of LEDs, the driver
`
`comprsing a plurality of LED pins, a minimum voltage sampler, a gain circuit, a
`
`first comparator, a second comparator and a logic circuit, wherein:
`
`the plurality of LEDs are each electrically connected to one of the plurality of
`
`LEDs;
`
`the minimum voltage sampler samples and outputs a minimum value from
`
`8
`
`IPR2020-01176 Page 00008
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`

`

`CN 101719345 A
`
`Claims
`
`
`
`8/14
`
`among voltages on the plurality of LED pins;
`
`the gain circuit generates a first signal according to the minimum value;
`
`the first comparator compares the first signal and a first reference voltage to
`
`generate a second signal;
`
`the second comparator compares the first signal and a second reference voltage
`
`to generate a third signal; and
`
`the logic circuit generates a digital output signal according to the second signal,
`
`the third signal and a digital input signal.
`
`35. The driver according to claim 34, wherein the gain circuit comprises a
`
`compensating circuit used for compensating on an error of the digital output
`
`signal arising from temperature.
`
`36. The driver according to claim 34, wherein the gain circuit comprises a controller
`
`used for controlling the gain of the gain circuit.
`
`37. A control method of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a plurality of drivers, each of which is
`
`provided with a plurality of LED pins each electrically connected to one of the
`
`plurality of LEDs, wherein the control method comprises the following steps:
`
`a first step: converting a direct current high voltage into at least one direct
`
`current low voltage and supplying it to a plurality of LEDs;
`
`a second step: monitoring voltages on the plurality of LED pins; and
`
`a third step: adjusting the direct current low voltage according to at least one of
`
`the voltages on the plurality of LED pins.
`
`38. The control method according to claim 37, wherein the direct current high
`
`voltage is converted from an alternating current voltage.
`
`39. The control method according to claim 37, wherein the step of adjusting the
`
`direct current low voltage according to at least one of the voltages on the
`
`plurality of LED pins comprises:
`
`a first step: selecting a minimum value from among voltages on the plurality of
`
`LED pins; and
`
`9
`
`IPR2020-01176 Page 00009
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`

`CN 101719345 A
`
`Claims
`
`
`
`9/14
`
`a second step: amplifying the minimum value by using a gain to generate a
`
`feedback signal to adjust the direct current low voltage .
`
`40. The control method according to claim 39, wherein the control method further
`
`comprises compensating on an error of the feedback signal arising from
`
`temperature.
`
`41. The control method according to claim 39, wherein the control method further
`
`comprises controlling the gain.
`
`42. The control method according to claim 37, wherein the step of adjusting the
`
`direct current low voltage according to at least one of the voltages on the
`
`plurality of LED pins comprises:
`
`a first step: selecting a minimum value from among voltages on the plurality of
`
`LED pins
`
`a second step: amplifying the minimum value by using a gain to generate a first
`
`signal;
`
`a third step: generating a second signal according to a feedback signal on a
`
`feedback signal node and the first signal;
`
`a fourth step: controlling the charge and discharge of the feedback signal node
`
`according to the second signal to generate the feedback signal to adjust the
`
`direct current low voltage.
`
`43. The control method according to claim 42, wherein the control method further
`
`comprises compensating on an error of the feedback signal arising from
`
`temperature.
`
`44. The control method according to claim 42, wherein the control method further
`
`comprises controlling the gain.
`
`45. The control method according to claim 37, wherein the step of adjusting the
`
`direct current low voltage according to at least one of the voltages on the
`
`plurality of LED pins comprises:
`
`a first step: sampling and outputting a minimum value among voltages on the
`
`plurality of LED pins; and
`
`10
`
`IPR2020-01176 Page 00010
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`

`

`CN 101719345 A
`
`Claims
`
`
`
`10/14
`
`a second step: amplifying the minimum value by using a gain to generate a
`
`feedback signal to adjust the direct current low voltage .
`
`46. The control method according to claim 45, wherein the control method further
`
`comprises compensating on an error of the feedback signal arising from
`
`temperature.
`
`47. The control method according to claim 45, wherein the control method further
`
`comprises controlling the gain.
`
`48. A control method of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a plurality of drivers provided with a
`
`plurality of LED pins each electrically connected to one of the plurality of LEDs,
`
`each of the drivers comprising a plurality of current sources, and each of the
`
`current sources being provided with a resistor, a transistor electrically connected
`
`between one of the plurality of LED pins and the resistor, and an operational
`
`amplifier provided with a first input electrically connected to a voltage end, a
`
`second input electrically connected to a node between the resistor and the
`
`transistor, and an output electrically connected to a gate of the transistor,
`
`wherein the control method comprises the following steps:
`
`a first step: converting a direct current high voltage into at least one direct
`
`current low voltage and supplying it to a plurality of LEDs;
`
`a second step: monitoring voltages on the gates of the plurality of transistors;
`
`and
`
`a third step: adjusting the direct current low voltage according to at least one of
`
`the voltages on the gates of the plurality of transistors.
`
`49. The control method according to claim 48, wherein the direct current high
`
`voltage is converted from an alternating current voltage.
`
`50. The control method according to claim 48, wherein the step of adjusting the
`
`direct current low voltage according to at least one of the voltages on the gates
`
`of the plurality of transistors comprises:
`
`a first step: selecting a maximum value from among voltages on the plurality of
`
`LED pins; and
`
`11
`
`IPR2020-01176 Page 00011
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`

`

`CN 101719345 A
`
`Claims
`
`
`
`11/14
`
`a second step: reducing the maximum value by using a gain to generate a
`
`feedback signal to adjust the direct current low voltage.
`
`51. The control method according to claim 48, wherein the control method further
`
`comprises controlling the gain.
`
`52. A control method of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a plurality of drivers, each of the drivers
`
`being provided with a plurality of LED pins each electrically connected to one
`
`of the plurality of LEDs, wherein the control method comprises the following
`
`steps:
`
`a first step: converting a direct current high voltage into at least one direct
`
`current low voltage and supplying it to a plurality of LEDs;
`
`a second step: generating a second digital signal as a first digital signal of next
`
`driver according to a minimum value among voltages on the plurality of LED
`
`pins of each of the drivers and a first digital signal; and
`
`a third step: adjusting the direct current low voltage according to a second
`
`digital signal output by the last driver.
`
`53. The control method according to claim 52, wherein the direct current high
`
`voltage is converted from an alternating current voltage.
`
`54. The control method according to claim 52, wherein the step of generating a
`
`second digital signal according to a minimum value among voltages on the
`
`plurality of LED pins of each of the drivers and a first digital signal comprises:
`
`a first step: monitoring voltages on the plurality of LED pins;
`
`a second step: sampling and outputting a minimum value among voltages on the
`
`plurality of LED pins;
`
`a third step: amplifying the minimum value by using a gain to generate a first
`
`signal;
`
`a fourth step: comparing the first signal and a first reference voltage to generate
`
`a second signal;
`
`a fifth step: comparing the first signal and a second reference voltage to
`
`12
`
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`

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`
`Claims
`
`
`
`12/14
`
`generate a third signal; and
`
`a sixth step: generating the second digital signal according to the second signal,
`
`the third signal and the first digital signal.
`
`55. A control method of a driver of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a power converter providing an output
`
`voltage to the plurality of LEDs, the driver being provided with a plurality of
`
`LED pins each electrically connected to one of the plurality of LEDs, wherein
`
`the control method comprises the following steps:
`
`a first step: selecting a minimum value from among voltages on the plurality of
`
`LED pins; and
`
`a second step: amplifying the minimum value by using a gain to generate a
`
`feedback signal to adjust the output voltage.
`
`56. The control method according to claim 55, wherein the control method further
`
`comprises compensating on an error of the feedback signal arising from
`
`temperature.
`
`57. The control method according to claim 55, wherein the control method further
`
`comprises controlling the gain.
`
`58. A control method of a driver of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a power converter providing an output
`
`voltage to the plurality of LEDs, the driver being provided with a plurality of
`
`LED pins each electrically connected to one of the plurality of LEDs, and a
`
`plurality of current sources each being provided with a resistor, a transistor
`
`electrically connected between one of the plurality of LED pins and the resistor,
`
`and an operational amplifier provided with a first input electrically connected to
`
`a voltage end, a second input electrically connected to a node between the
`
`resistor and the transistor, and an output electrically connected to a gate of the
`
`transistor, wherein the control method comprises the following steps:
`
`a first step: selecting a maximum value from among voltages on transistor gates
`
`in the plurality of current sources; and
`
`a second step: reducing the maximum value by using a gain to generate a
`
`13
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`IPR2020-01176 Page 00013
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`

`CN 101719345 A
`
`Claims
`
`
`
`13/14
`
`feedback signal to adjust the output voltage.
`
`59. The control method according to claim 58, wherein the control method further
`
`comprises controlling the gain.
`
`60. A control method of a driver of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a power converter providing an output
`
`voltage to the plurality of LEDs, the driver being provided with a plurality of
`
`LED pins each electrically connected to one of the plurality of LEDs, wherein
`
`the control method comprises the following steps:
`
`a first step: selecting a minimum value from among voltages on the plurality of
`
`LED pins
`
`a second step: amplifying the minimum value by using a gain to generate a first
`
`signal;
`
`a third step: converting the first signal and a feedback signal on a feedback
`
`signal node to generate a second signal; and
`
`a fourth step: controlling the charge and discharge of the feedback signal node
`
`according to the second signal to generate the feedback signal to adjust the
`
`output voltage.
`
`61. The control method according to claim 60, wherein the control method further
`
`comprises compensating on an error of the feedback signal arising from
`
`temperature.
`
`62. The control method according to claim 60, wherein the control method further
`
`comprises controlling the gain.
`
`63. A control method of a driver of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a power converter providing an output
`
`voltage to the plurality of LEDs, the driver being provided with a plurality of
`
`LED pins each electrically connected to one of the plurality of LEDs, wherein
`
`the control method comprises the following steps:
`
`a first step: sampling and outputting a minimum value among voltages on the
`
`plurality of LED pins; and
`
`14
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`CN 101719345 A
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`Claims
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`14/14
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`a second step: amplifying the minimum value by using a gain to generate a
`
`feedback signal to adjust the output voltage.
`
`64. The control method according to claim 63, wherein the control method further
`
`comprises compensating on an error of the feedback signal arising from
`
`temperature.
`
`65. The control method according to claim 63, wherein the control method further
`
`comprises controlling the gain.
`
`66. A control method of a driver of an LED display system, the LED display system
`
`comprising a plurality of LEDs and a power converter providing an output
`
`voltage to the plurality of LEDs, the driver being provided with a plurality of
`
`LED pins each electrically connected to one of the plurality of LEDs, wherein
`
`the control method comprises the following steps:
`
`a first step: sampling and outputting a minimum value among voltages on the
`
`plurality of LED pins;
`
`a second step: amplifying the minimum value by using a gain to generate a first
`
`signal;
`
`a third step: comparing the first signal and a first reference voltage to generate a
`
`second signal;
`
`a fourth step: comparing the first signal and a second reference voltage to
`
`generate a third signal; and
`
`a fifth step: generating a digital output signal according to the second signal, the
`
`third signal and a digital input signal.
`
`67. The control method according to claim 66, wherein the control method further
`
`comprises compensating on an error of the first signal arising from temperature.
`
`68. The control method according to claim 66, wherein the control method further
`
`comprises controlling the gain.
`
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`CN 101719345 A
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`
`
`Description
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`
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`1/23
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`LED Display System and Control Method Thereof as well as Driver
`
`of LED Display System and Control Method Thereof
`
`TECHNICAL FIELD
`
`[0001] The present invention relates to an LED display system, specifically to a
`
`high-efficiency LED display system.
`
`
`
`BACKGROUND ART
`
`[0002] Fig. 1 shows a conventional LED display system 100 applied to billboards,
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`comprising an AC to DC converter 102 and a display panel 104, wherein the AC to
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`DC converter 102 provides a 5V power supply to the display panel 104. The display
`
`panel 104 comprises LED light sources 106, 110 and 114 and drivers 108, 112 and
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`116, which drive the LED light sources 106, 110 and 114 respectively, each LED light
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`source 106 comprises a plurality of LEDs 118, each LED light source 110 comprises a
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`plurality of LEDs 120, each LED light source 114 comprises a plurality of LEDs 122,
`
`the forward bias voltages of the LEDs 118 and 120 are about 2.2V, the forward bias
`
`voltages of the LEDs 122 are about 3.6V, while the voltage provided by the AC to DC
`
`converter 102 is 5V. Therefore, in order to prevent surplus voltage from causing
`
`overheating and damage of the LEDs 118, 120 and 122, each of the LEDs 118, 120
`
`and 122 is connected to a resistor Rc in series, and the resistor Rc serves as a heat
`
`sinker to share the heat on the LEDs 118, 120 and 122.
`
`[0003] However, there is a distance between the AC to DC converter 102 and the
`
`display panel 104, so the wire resistance Rp and Rg of the power line and ground line
`
`between the AC to DC converter 102 and the display panel 104 will consume quite
`
`some power. Further, although the resistor Rc can share the heat on the LEDs 118,
`
`120 and 122, it also causes power consumption, in other words, resistances Rp, Rg
`
`and Rc will cause reduction of the efficiency of the LED display system 100.
`
`[0004] Therefore, the known LED display system has the foregoing inconveniences
`
`and problems.
`
`
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`16
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`CN 101719345 A
`
`Description
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`
`
`2/23
`
`
`
`SUMMARY OF THE INVENTION
`
`[0005] An object of the present invention is to provide a high-efficiency LED
`
`display system and control method thereof.
`
`[0006] Another object of the present invention is to provide a driver of an LED
`
`display system and control method thereof.
`
`[0007] To achieve the foregoing objects, the present invention provides the
`
`following technical solution:
`
`[0008] An LED display system, comprising a plurality of LEDs, a plurality of
`
`drivers and a power converter, wherein:
`
`[0009]
`
`the plurality of LEDs are arranged in the display system;
`
`[0010]
`
`the plurality of drivers are used for driving the plurality of LEDs, each of the
`
`drivers is provided with a plurality of LED pins, the plurality of LEDs are each
`
`electrically connected to one of the plurality of LEDs, and each of the drivers outputs
`
`a feedback signal at a feedback signal node;
`
`[0011]
`
`the power converter is arranged in the display system and used for receiving
`
`a direct current high voltage, converting the direct current high voltage into at least
`
`one direct current low voltage to the plurality of LEDs, and adjusting the at least one
`
`direct current low voltage according to one of the plurality of feedback signals.
`
`[0012] The LED display system of the present invention can be further achieved by
`
`taking the following technical measures.
`
`[0013] The foregoing LED display system, wherein the LED display