TW202410004A - Ghost image elimination circuit of LED display, LED driver chip, and LED display device capable of effectively reducing the chip area of the LED driver chip and lowering the static power consumption - Google Patents

Abstract

Provided is a ghost image elimination circuit of an LED display, which includes: a common amplifier having a voltage output end to output a ghost image elimination voltage; and a plurality of switches coupled between the voltage output end and a plurality of current source output ends, and correspondingly controlled by a plurality of switching signals, wherein the current source output ends are used to be coupled with an LED array. During operation, when a selected one of the current source output ends is disabled, a corresponding one of the switching signals is presented in an active state to turn on a corresponding one of the switches to provide the ghost image elimination voltage to the selected current source output end, thereby providing a ghost image elimination function for the LED array.

Description

LED display elimination circuit, LED driver chip and LED display device

The present invention relates to an LED driving circuit, and more particularly to a video elimination circuit for an LED display.

In order to solve the afterimage problem of LED display, a general LED driver chip will set a shadow elimination circuit in each current output channel. Please refer to Figure 1, which shows a circuit diagram of a current output channel of an existing LED driver chip. As shown in Figure 1, a current output channel 11 has a first NMOS (N-type metal oxide semiconductor) transistor 11a, a second NMOS (N-type metal oxide semiconductor) transistor 11b, a first amplifier 11c and a second amplifier 11d.

The first NMOS transistor 11a generates a constant current according to a control voltage V _B1 ; the second NMOS transistor 11b serves as a switch of the current output channel 11 to control whether to output current to an LED pixel unit; the first amplifier 11c depends on a The control voltage V _B2 sets the drain voltage of the first NMOS transistor 11a and the gate voltage of the second NMOS transistor 11b to control the opening and closing of the second NMOS transistor 11b; and the second amplifier 11d acts as an elimination circuit. , used to set the shadow erasing voltage when the output channel 11 is closed according to a control voltage V _B3 to perform a shadow erasing operation, that is, when the output channel 11 is closed, the voltage of the output terminal OUT is raised to drive the LED pixel unit The current quickly returns to zero, thereby eliminating the residual image of the LED pixel unit.

However, as the number of output channels increases, the number of cancellation circuits will also increase, occupying more chip area and increasing static power consumption.

In order to solve the above-mentioned problems, there is an urgent need in this field for a novel shadow elimination circuit for LED displays.

The main purpose of the present invention is to disclose a LED display screen elimination circuit, which can effectively reduce the chip area of an LED driver chip and reduce its static power consumption by allowing multiple current output channels to share an amplifier.

Another object of the present invention is to disclose an LED driver chip that can effectively reduce the chip area and reduce the static power consumption of the chip through the above-mentioned shadow erasing circuit.

Another object of the present invention is to disclose a display device that can effectively reduce the chip area of its LED driver chip and reduce its static power consumption by using the above-mentioned shadow erasing circuit.

To achieve the above-mentioned purpose, a shadow cancellation circuit for an LED display is proposed, which includes: A common amplifier having a voltage output terminal to output a shadow cancellation voltage; and A plurality of switches coupled between the voltage output terminal and a plurality of current source output terminals, which are correspondingly controlled by a plurality of switch signals, and the current source output terminals are used to couple with an LED array; During operation, when a selected current source output terminal is disabled, a corresponding switch signal will be in an active state to turn on a corresponding switch to provide the shadow cancellation voltage for the selected current source output terminal, thereby providing a shadow cancellation function for the LED array.

In a possible embodiment, the LED array may be a common anode LED array or a common cathode LED array.

In one embodiment, the current source output terminals are output terminals of a plurality of current output channels, and each current output channel has: A first NMOS transistor has a first gate, a first drain and a first source, the first gate is used to couple a first control voltage, the first source is coupled to a reference place; A second NMOS transistor has a second gate, a second drain and a second source, the second drain is coupled to the output terminal of the current source, and the second source is coupled to the first a drain; and An amplifier has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is used to couple to a second control voltage, the positive input terminal is coupled to the second source, and the output The terminal is coupled to the second gate.

In one embodiment, the common amplifier has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is coupled to the output terminal, the positive input terminal is used to couple a third control voltage, and the output terminal is coupled to the voltage output terminal.

In order to achieve the aforementioned object, the present invention further proposes an LED driver chip, which has a plurality of current output channels and a shadow elimination circuit. The shadow elimination circuit includes: a common amplifier having a voltage output terminal to output an elimination voltage; and A plurality of switches, coupled between the voltage output terminal and the current output terminals of the current output channels, are controlled by a plurality of switch signals correspondingly, and the current output terminals of the current output channels are used to coupled with an LED array; During operation, when a selected current output channel is disabled, a corresponding switch signal will assume an active state to turn on a corresponding switch for the selected current output channel. The current output terminal provides the shadow elimination voltage, thereby providing a shadow elimination function for the LED array.

In a possible embodiment, the LED array may be a common anode LED array or a common cathode LED array.

In one embodiment, each of the current output channels has: a first NMOS transistor having a first gate, a first drain and a first source, the first gate being used to couple a first control voltage, and the first source being coupled to a reference ground; a second NMOS transistor having a second gate, a second drain and a second source, the second drain being coupled to the current output terminal, and the second source being coupled to the first drain; and an amplifier having a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is used to couple a second control voltage, the positive input terminal is coupled to the second source, and the output terminal is coupled to the second gate.

In one embodiment, the common amplifier has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is coupled to the output terminal, the positive input terminal is used to couple a third control voltage, and the output terminal is coupled to the voltage output terminal.

In order to achieve the above object, the present invention further proposes an LED display device, which has the above-mentioned LED driver chip.

In a possible embodiment, the LED array may be a micro-sub-millimeter light-emitting diode array, a micro-light-emitting diode array or a quantum dot light-emitting diode array.

In order to enable the Review Committee to further understand the structure, features and purpose of the present invention, the following are attached with drawings and detailed descriptions of preferred specific embodiments.

The principle of the present invention is to set up a common amplifier and a plurality of switches in the LED driver chip to perform the ghosting operation on each current output channel, thereby eliminating the ghosting amplifier in each output channel, thereby reducing the area and saving money. cost and reduce static power consumption.

Please refer to FIG. 2 , which shows a circuit diagram of an embodiment of the LED driver chip of the present invention. As shown in FIG. 2 , an LED driver chip 100 has a shadow cancellation circuit 110 and a plurality of current output channels 121 , wherein the shadow cancellation circuit 110 has a common amplifier 111 and a plurality of switches 112 .

The common amplifier 111 has a voltage output terminal for outputting an erasing voltage, and generates the erasing voltage according to a control voltage V _B3 . Specifically, the common amplifier 111 has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is coupled to the output terminal, and the positive input terminal is used to couple to the third control voltage V _B3 , And the output terminal is coupled to the voltage output terminal.

The switches 112 are coupled between the voltage output terminal and the current output terminals OUT ₁ -OUT _n of the current output channels 121 and are correspondingly controlled by a plurality of switch signals S ₁ -S _n . The current source output terminals OUT ₁ -OUT _n are used to couple with an LED array (not shown), where n is an integer greater than 1.

In detail, each current output channel 121 has a first NMOS transistor 121a, a second NMOS transistor 121b and an amplifier 121c.

The first NMOS transistor 121a has a first gate, a first drain and a first source. The first gate is used to couple a first control voltage V _B1 , and the first source is coupled to a reference ground.

The second NMOS transistor 121b has a second gate, a second drain and a second source. The second drain is coupled to a current source output terminal OUT _j , where j is between 1 and n. an integer, and the second source is coupled to the first drain.

The amplifier 121c has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is used to couple to a second control voltage V _B2 , the positive input terminal is coupled to the second source, and the The output terminal is coupled to the second gate.

During operation, when a selected current source output terminal OUT _j is disabled, a corresponding switch signal S _j will be in an active state to turn on a corresponding switch 112 to provide the selected current source output terminal OUT _j. Elimination voltage, thereby providing a shadow elimination function for the LED array.

In addition, the LED array may be a common anode LED array or a common cathode LED array.

In addition, according to the above description, the present invention further provides an LED display device. Please refer to FIG. 3 , which illustrates a block diagram of an embodiment of the LED display device of the present invention. As shown in FIG. 3 , an LED display device 200 has an LED array 210 and an LED driver chip 220 for driving the LED array 210 . The LED driver chip 220 is implemented by the LED driver chip 100 . In addition, the LED array 210 may be a sub-millimeter LED array, a micro LED array or a quantum dot LED array.

Through the above disclosed design, the present invention has the following advantages: 1. The shadow cancellation circuit of the LED display of the present invention can effectively reduce the chip area of an LED driver chip and reduce its static power consumption by allowing multiple current output channels to share an amplifier. 2. The LED driver chip of the present invention can effectively reduce the chip area and reduce the static power consumption of the chip through the above shadow cancellation circuit. 3. The display device of the present invention can effectively reduce the chip area of its LED driver chip and reduce its static power consumption through the above shadow cancellation circuit.

What is disclosed in this case is a preferred embodiment. Any partial changes or modifications derived from the technical ideas of this case and easily inferred by those familiar with the art will not deviate from the scope of the patent rights of this case.

In summary, this case shows that its purpose, means and effects are all different from the known technology, and it is the first invention that is practical and indeed meets the patent requirements for invention. We sincerely request the review committee to examine this carefully and grant a patent as soon as possible to benefit the society. This is our utmost prayer.

11: Current output channel 11a: First NMOS transistor 11b: Second NMOS transistor 11c: First amplifier 11d: Second amplifier 100: LED driver chip 110: Shadow elimination circuit 111: Common amplifier 112: Switch 121: Current output channel 121a: First NMOS transistor 121b: Second NMOS transistor 121c: Amplifier 200: LED display device 210: LED array 220: LED driver chip

FIG. 1 shows a circuit diagram of a current output channel of a conventional LED driver chip. FIG. 2 shows a circuit diagram of an embodiment of the LED driver chip of the present invention. FIG. 3 is a block diagram of an embodiment of the LED display device of the present invention.

100:LED driver chip

110: Shadow elimination circuit

111:Shared amplifier

112: switch

121:Current output channel

121a: first NMOS transistor

121b: Second NMOS transistor

121c:Amplifier

Claims (10)

A shadow cancellation circuit for an LED display, comprising: a common amplifier having a voltage output terminal for outputting a shadow cancellation voltage; and a plurality of switches coupled between the voltage output terminal and a plurality of current source output terminals, which are correspondingly controlled by a plurality of switch signals, and the current source output terminals are used to couple with an LED array; during operation, when a selected current source output terminal is disabled, a corresponding switch signal will be in an active state to turn on a corresponding switch to provide the shadow cancellation voltage for the selected current source output terminal, thereby providing a shadow cancellation function for the LED array. For example, the shadow elimination circuit of an LED display as described in item 1 of the patent application scope, wherein the LED array is a common positive LED array or a common negative LED array. For example, in the shadow erasing circuit of an LED display described in item 1 of the patent application, the current source output terminals are the output terminals of a plurality of current output channels, and each of the current output channels has: A first NMOS transistor has a first gate, a first drain and a first source, the first gate is used to couple a first control voltage, the first source is coupled to a reference place; A second NMOS transistor has a second gate, a second drain and a second source, the second drain is coupled to the output terminal of the current source, and the second source is coupled to the first a drain; and An amplifier has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is used to couple to a second control voltage, the positive input terminal is coupled to the second source, and the output The terminal is coupled to the second gate. As described in item 3 of the patent application scope, the common amplifier has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is coupled to the output terminal, the positive input terminal is used to couple a third control voltage, and the output terminal is coupled to the voltage output terminal. An LED driver chip has a plurality of current output channels and a blanking circuit, the blanking circuit comprising: a common amplifier having a voltage output terminal for outputting a blanking voltage; and a plurality of switches coupled between the voltage output terminal and the current output terminals of the current output channels, which are correspondingly controlled by a plurality of switch signals, and the current output terminals of the current output channels are used to couple with an LED array; during operation, when a selected current output channel is disabled, a corresponding switch signal will be in an active state to turn on a corresponding switch to provide the blanking voltage to the current output terminal of the selected current output channel, thereby providing a blanking function for the LED array. As described in item 5 of the patent application scope, the LED driver chip, wherein the LED array is a common anode LED array or a common cathode LED array. For example, in the LED driver chip described in item 5 of the patent application, each current output channel has: A first NMOS transistor has a first gate, a first drain and a first source, the first gate is used to couple a first control voltage, the first source is coupled to a reference place; A second NMOS transistor has a second gate, a second drain and a second source, the second drain is coupled to one of the current output terminals, and the second source is coupled to the first drain; and An amplifier has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is used to couple to a second control voltage, the positive input terminal is coupled to the second source, and the output The terminal is coupled to the second gate. As described in Item 7 of the patent application scope, the common amplifier has a negative input terminal, a positive input terminal and an output terminal, wherein the negative input terminal is coupled to the output terminal, the positive input terminal is used to couple a third control voltage, and the output terminal is coupled to the voltage output terminal. An LED display device having an LED driver chip as described in any one of items 5 to 8 of the patent application. As described in Item 9 of the patent application, the LED display device, wherein the LED array is a display element array selected from a group consisting of a sub-millimeter light-emitting diode array, a micro-light-emitting diode array and a quantum dot light-emitting diode array.

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