TWI865279B - Elimination circuit, LED display device and information processing device - Google Patents

Abstract

The present invention discloses a shadow elimination circuit, comprising: a plurality of shadow elimination voltage establishing elements, a voltage buffer, a voltage source, and a voltage adjustment unit, wherein each of the shadow elimination voltage establishing elements has a control end, a first electrical end, and a second electrical end, and the first electrical end is electrically connected to a gate line to be coupled between a row of LED lamp beads and a switch element of an LED row scanning circuit. Furthermore, the voltage source transmits an enabling voltage to the second electrical end through the voltage buffer, thereby enabling the shadow elimination voltage establishing element to be turned on to establish a shadow elimination voltage at a contact point between the switch element and the LED lamp bead. In particular, the voltage adjustment unit is used to generate an adjustment voltage and transmit it to the control end, thereby increasing the terminal voltage of the control end, thereby increasing the voltage upper limit of the first electrical end and reducing the channel resistance of the blanking voltage establishment element, so that the blanking voltage can have a larger modulation range and a faster establishment speed.

Description

Elimination circuit, LED display device and information processing device

The present invention relates to the technical field of LED display, and in particular to a blanking circuit for generating blanking voltage.

Light-emitting diodes (LEDs) are widely used light-emitting components. Due to their small size and long service life, they are widely used in lighting and display devices. LED display devices are self-luminous flat display devices with bright colors, wide dynamic range, high brightness, long service life, and high reliability. LED display devices with large screens have been widely used in large squares, commercial advertisements, stadiums, information dissemination, news releases, and stock exchanges as a public display medium.

FIG1 is a block diagram of a known LED display. As shown in FIG1 , the known LED display 1a mainly includes: an LED panel 11a, an LED row scanning circuit 12a, and at least one LED source driver chip 13a, wherein the LED panel 11a includes M×N LED lamp beads 111a, M gate lines (or scanning lines) 11Ga, and N source lines (or data lines) 11Sa, and M and N are both positive integers. It is worth noting that the M×N LED lamp beads 111a can be regarded as being arranged in M rows (Lines) or in N columns (Columns). Moreover, the LED source driver chip 13a is usually a multi-channel constant current driver chip. Electronic engineers familiar with the design and manufacture of LED displays know that the LED row scanning circuit 12a includes M first switch elements 121a correspondingly connected to M gate lines 11Ga, and the LED source driver chip 13a includes N channel current generators 131a correspondingly connected to N source lines 11Sa.

In normal operation, the first switch element 121a of the i-th row turns on the N LED beads 111a of the i-th row, and the channel current generator 131a of the j-th column adjusts the brightness of the M LED beads 111a of the j-th column; where i∈M and j∈N. However, when actually controlling the LED panel 11a to display images, the following situation often occurs: when some LED beads 111a are turned on, other unlit LED beads 111a are dimly lit. Therefore, the prior art further adds a blanking circuit including a control unit 20a and M second switching elements 21a controlled by the control unit 20a in the LED display 1a, so that the second switching element 21a in the i-th row is coupled between the gate line 11Ga in the i-th row and the LED lamp bead 111a in the i-th row. Designed in this way, when the N LED lamp beads 111a in the i-th row are turned off through the first switch element 121a in the i-th row, the control unit 20a transmits a control signal to the second switch element 21a in the i-th row, thereby turning on the second switch element 21a to provide a current discharge path for the parasitic capacitor 110a in the i-th row, thereby maintaining the voltage on the gate line 11Ga of the i-th row at a stable voltage value (called blanking voltage), and the blanking voltage can reduce or prevent the voltage coupling between the i-th row and the i+1-th row and/or the i-1-th row.

FIG2 is a circuit diagram of the shadow elimination circuit shown in FIG1. As shown in FIG1 and FIG2, since the M×N LED lamp beads 111a adopt a common cathode connection method, the channel current generator 131a of the jth column is equivalent to a current source 130a coupled to the LED lamp beads 111a. In addition, as shown in FIG2, the control unit 20a includes a voltage buffer 22a and a voltage source 23a, and the second switch element 21a is a MOSFT element. It should be understood that when the N LED lamp beads 111a in the i-th row are turned off through the first switching element 121a in the i-th row, the control unit 20a transmits a source voltage (i.e., the aforementioned control signal) to the second switching element 21a through the voltage buffer 22a, thereby establishing a blanking voltage V _BK between the first switching element 121a in the i-th row and the LED lamp beads 111a through the second switching element 21a.

It is easy to understand that the speed of establishing the blanking voltage V _BK is positively correlated with the internal resistance of the MOSFET element and the driving ability of the voltage buffer 22a. However, practical experience shows that when the MOSFET element (i.e., the second switch element 21a) is turned on, the voltage range of its source/drain is VTHN~VDD. Therefore, it should be considered to change the design or improve the existing blanking circuit 2a so that when the MOSFET element is turned on, the voltage range of its source/drain can be expanded to 0V~VDD, so as to achieve the effect of reducing the internal resistance of the MOSFET element. Although the MOSFET element can be connected in parallel with a P-type MOSFET element to solve the above-mentioned problem, this approach increases the circuit area of the blanking circuit 2a (because M P-type MOSFET elements are required), which is obviously not a cost-effective solution. In summary, it is necessary to consider changing the design or improving the known image cancellation circuit 2a to solve the above-mentioned related defects.

From the above description, it can be seen that a new type of image elimination circuit is urgently needed in this field.

The main purpose of the present invention is to provide a shadow cancellation circuit for providing a shadow cancellation voltage for an LED panel, which includes: a plurality of shadow cancellation voltage establishment components, a voltage buffer, a voltage source, and a voltage adjustment unit. According to the present invention, the voltage adjustment unit is used to generate an adjustment voltage and transmit it to the shadow cancellation voltage establishment component, thereby increasing the voltage of a control end of the shadow cancellation voltage establishment component, thereby increasing the voltage upper limit of the channel output end of the shadow cancellation voltage establishment component and reducing the channel resistance of the shadow cancellation voltage establishment component, so that the shadow cancellation voltage can have a larger modulation range and a faster establishment speed.

To achieve the above-mentioned purpose, the present invention proposes an embodiment of the above-mentioned shadow cancellation circuit, which includes: A plurality of shadow cancellation voltage establishing elements, wherein each of the above-mentioned shadow cancellation voltage establishing elements has a control end, a first electrical end and a second electrical end, and the first electrical end is electrically connected to a gate line to couple between a row of LED lamp beads and a switch element of an LED row scanning circuit; A control unit, coupled to the second electrical end, and configured to transmit an enable voltage to the second electrical end, thereby enabling the shadow cancellation voltage establishing element to establish a shadow cancellation voltage at a contact point between the switch element and the LED lamp bead; and A voltage adjustment unit is coupled to the control end and used to generate an adjustment voltage and transmit it to the control end so that the voltage at one end of the control end is adjusted to a target voltage.

In one embodiment, the blanking voltage establishing element is an N-type MOSFET element, and the control terminal, the first electrical terminal and the second electrical terminal are respectively the gate terminal, the drain terminal and the source terminal of the N-type MOSFET element.

In one embodiment, the voltage adjustment unit includes a boost circuit for generating the adjustment voltage and transmitting it to the gate terminal of the N-type MOSFET element, thereby increasing a gate terminal voltage of the N-type MOSFET element to a target voltage, and the target voltage is not lower than the sum of a power supply voltage and a critical voltage (Threshold voltage).

In one embodiment, after the gate voltage is increased to the target voltage, a source-drain voltage of the N-type MOSFET element is between a first voltage and a second voltage.

Furthermore, the present invention also proposes an embodiment of an LED display device, which includes: an LED panel, an LED row scanning circuit and at least one LED source driver chip, wherein the LED panel includes M×N LED lamp beads, M gate lines and N source lines, the LED row scanning circuit includes M switch elements correspondingly connected to the M gate lines, the LED source driver chip includes N channel current generators correspondingly connected to the N source lines, and M and N are both positive integers; its feature is that the LED display device further includes M shadow elimination circuits, so that the shadow elimination circuits are electrically connected to the gate lines and thus coupled between the LED lamp beads and the switch elements, and the shadow elimination circuits include: A plurality of blanking voltage establishing elements, wherein each blanking voltage establishing element has a control end, a first electrical end and a second electrical end, and the first electrical end is electrically connected to a gate line to couple between a row of LED lamp beads and a switch element of an LED row scanning circuit; A control unit, coupled to the second electrical end, and configured to transmit an enable voltage to the second electrical end, thereby enabling the blanking voltage establishing element to establish a blanking voltage at a contact point between the switch element and the LED lamp bead; and A voltage adjustment unit, coupled to the control end, and used to generate an adjustment voltage and transmit it to the control end, so that the voltage at one end of the control end is adjusted to a target voltage.

In one embodiment, the blanking voltage establishing element is an N-type MOSFET element, and the control terminal, the first electrical terminal and the second electrical terminal are respectively the gate terminal, the drain terminal and the source terminal of the N-type MOSFET element.

In one embodiment, the voltage adjustment unit includes a boost circuit for generating the adjustment voltage and transmitting it to the gate terminal of the N-type MOSFET element, thereby increasing a gate terminal voltage of the N-type MOSFET element to a target voltage, and the target voltage is not lower than the sum of a power supply voltage and a critical voltage (Threshold voltage).

In one embodiment, after the gate voltage is increased to the target voltage, a source-drain voltage of the N-type MOSFET element is between a first voltage and a second voltage.

In one embodiment, the M×N LED lamp beads are electrically connected to the M gate lines and the N source lines in a common cathode connection manner, and the LED source driver chip is a current source type multi-channel constant current driver chip.

In one embodiment, the M×N LED lamp beads are electrically connected to the M gate lines and the N source lines in a common anode connection manner, and the LED source driver chip is a current sink type multi-channel constant current driver chip.

Furthermore, the present invention also provides an information processing device, characterized in that it includes at least one LED display device of the present invention as described above. In a feasible embodiment, the information processing device is an electronic device selected from the group consisting of a TV wall, an electronic advertising billboard, a smart TV, a tablet computer, a laptop computer, an all-in-one computer, a car entertainment device, a kiosk, a video door machine, a smart watch, a digital camera, and a head-mounted display device.

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

FIG3 is a first block diagram of an LED device including a shadow elimination circuit of the present invention. As shown in FIG3, the LED display device 1 mainly includes: an LED panel 11, an LED row scanning circuit 12, and at least one LED source driver chip 13, wherein the LED panel 11 includes M×N LED lamp beads 111, M gate lines (or scanning lines) 11G, and N source lines (or data lines) 11S. In addition, the LED row scanning circuit 12 includes M switch elements 121 correspondingly connected to the M gate lines 11G, and the LED source driver chip 13 includes N channel current generators 131 correspondingly connected to the N source lines 11S. It is worth noting that the M×N LED lamp beads 111 can be considered to be arranged in M rows (Lines) or arranged in N columns (Columns), and both M and N are positive integers.

Fig. 4 is a first circuit diagram of a shadow elimination circuit of the present invention. As shown in Fig. 3 and Fig. 4, since the M×N LED lamp beads 111 are electrically connected to the M gate lines 11G and the N source lines 11S in a common cathode connection mode, the LED source driver chip 13 is a current source type multi-channel constant current driver chip, and the channel current generator 131 corresponding to the source line 11S of the jth column is equivalent to a current source 13S to couple the LED lamp beads 111 through the source line 11S. Furthermore, according to the design of the present invention, the shadow elimination circuit 2 includes: a plurality of shadow elimination voltage establishing elements 21, a control unit 20 and a voltage adjustment unit 24, wherein each of the shadow elimination voltage establishing elements 21 has a control terminal, a first electrical terminal and a second electrical terminal, and the first electrical terminal is electrically connected to a gate line 11G so as to be coupled between a row of LED beads 111 and a switch element 121 of an LED row scanning circuit 12. In one embodiment, the shadow elimination voltage establishing element 21 is an N-type MOSFET element, and the control terminal, the first electrical terminal and the second electrical terminal are the gate terminal, the drain terminal and the source terminal of the N-type MOSFET element respectively.

In more detail, the control unit 20 includes a voltage buffer 22 and a voltage source 23. In this design, when the N LED lamp beads 111 in the i-th row are turned off through the switch element 121 in the i-th row, the control unit 20 transmits an adjustment voltage to the blanking voltage establishment element 21 in the i-th row, thereby turning on the blanking voltage establishment element 21 to provide a blanking voltage for the parasitic capacitor 110 in the i-th row to make the LED lamp beads 111 reverse biased.

According to the design of the present invention, the voltage adjustment unit 24 is coupled to the control terminal (i.e., the gate terminal of the N-type MOSFET element), and is used to generate an adjustment voltage and transmit it to the gate terminal to increase the voltage of the gate terminal to a target voltage. In one embodiment, the voltage adjustment unit 24 includes a boost circuit, which is used to generate the adjustment voltage and transmit it to the gate terminal of the N-type MOSFET element (i.e., the control terminal of the blanking voltage establishment element 21), and the target voltage is not lower than the sum of a power supply voltage and a critical voltage (Threshold voltage), that is, greater than or equal to VDD+VTHN. Thus, after the gate voltage is increased to the target voltage, the upper limit of the drain voltage of the N-type MOSFET element can be no less than VDD.

Furthermore, FIG. 5 is a second block diagram of an LED device including the shadow cancellation circuit of the present invention. And, FIG. 6 is a second circuit diagram of the shadow cancellation circuit of the present invention. As shown in FIG. 5 and FIG. 6, since the M×N LED lamp beads 111 are electrically connected to the M gate lines 11G and the N source lines 11S in a common anode connection manner, the LED source driver chip 13 is a current sink type multi-channel constant current driver chip, and the channel current generator 131 corresponding to the source line 11S of the j-th column is equivalent to a current sink 13K to couple the LED lamp beads 111 through the source line 11S.

Similarly, the shadow elimination circuit 2 of the present invention includes: a plurality of shadow elimination voltage establishing elements 21, a control unit 20 and a voltage adjustment unit 24, wherein each of the shadow elimination voltage establishing elements 21 has a control end, a first electrical end and a second electrical end, and is electrically connected to a gate line 11G with its first electrical end so as to be coupled between a row of LED lamp beads 111 and a switch element 121 of an LED row scanning circuit 12. In addition, the control unit 20 includes a voltage buffer 22 and a voltage source 23, and is configured to transmit a voltage to the second electrical end, so as to enable the shadow elimination voltage establishing element 21 to establish a shadow elimination voltage at a contact point between the switch element 121 and the LED lamp bead 111. Furthermore, the voltage adjustment unit 24 is coupled to the control end and is used to generate an adjustment voltage and transmit it to the control end, so that the voltage at one end of the control end is adjusted to a target voltage, so as to increase the voltage upper limit of the channel output end (the first electrical end) of the blanking voltage establishment element 21 and reduce the channel resistance of the blanking voltage establishment element, thereby allowing the blanking voltage to have a larger modulation range and a faster establishment speed.

Thus, the above description has completely and clearly explained the image elimination circuit of the present invention; and, from the above description, it can be known that the present invention has the following advantages:

(1) The present invention discloses a blanking circuit for providing a blanking voltage for an LED panel, which includes: a plurality of blanking voltage establishing components, a voltage buffer, a voltage source, and a voltage adjustment unit. According to the present invention, the voltage adjustment unit is used to generate an adjustment voltage and transmit it to the blanking voltage establishing component, thereby raising the terminal voltage of a control terminal of the blanking voltage establishing component, thereby raising the voltage upper limit of the channel output terminal of the blanking voltage establishing component and reducing the channel resistance of the blanking voltage establishing component, so that the blanking voltage can have a larger modulation range and a faster establishment speed.

(2) In addition, the present invention also proposes a display device, which is characterized in that it includes an LED row scanning circuit, at least one LED source driver chip, an LED panel including M×N LED lamp beads, M gate lines and N source lines, and M image cancellation circuits of the present invention as described above.

(3) Furthermore, the present invention also provides an information processing device, characterized in that it includes at least one LED display device of the present invention as described above. In a feasible embodiment, the information processing device is an electronic device selected from the group consisting of a TV wall, an electronic advertising billboard, a smart TV, a tablet computer, a laptop computer, an all-in-one computer, a car entertainment device, a kiosk, a video door machine, a smart watch, a digital camera, and a head-mounted display device.

It must be emphasized that what is disclosed in the above-mentioned case is a preferred embodiment. Any partial changes or modifications that are derived from the technical ideas of this case and are easily inferred by people familiar with the art do not deviate from the scope of the patent rights of this case.

In summary, this case shows that its purpose, means and effects are very 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.

1a:LED display

11a: LED Panel

110a: Parasitic capacitance

111a:LED lamp beads

11Ga: Gate line

11Sa: Source line

12a: LED line scanning circuit

121a: first switch element

13a: LED source driver chip

130a: Current source

2a: Cancellation circuit

20a: Control unit

21a: Second switch element

22a: Voltage buffer

23a: Voltage source

1:LED display device

11:LED Panel

110: Parasitic capacitance

111:LED lamp beads

11G: Gate line

11S: Source line

12: LED line scanning circuit

121: Switching components

13:LED source driver chip

13S: Current source

13K:Current tank

2: Cancellation circuit

20: Control unit

21: Elimination voltage establishment element

22: Voltage Buffer

23: Voltage source

24: Voltage adjustment unit

FIG. 1 is a block diagram of a known LED display; FIG. 2 is a circuit diagram of the shadow cancellation circuit shown in FIG. 1; FIG. 3 is a first block diagram of an LED device including a shadow cancellation circuit of the present invention; FIG. 4 is a first circuit diagram of a shadow cancellation circuit of the present invention; FIG. 5 is a second block diagram of an LED device including the shadow cancellation circuit of the present invention; and FIG. 6 is a second circuit diagram of the shadow cancellation circuit of the present invention.

110: Parasitic capacitance

111:LED lamp beads

11G: Gate line

11S: Source line

121: Switching components

13S: Current source

2: Cancellation circuit

21: Elimination voltage establishment element

22: Voltage buffer

23: Voltage source

24: Voltage adjustment unit

Claims (11)

A shadow elimination circuit includes: a plurality of shadow elimination voltage establishing elements, wherein each of the shadow elimination voltage establishing elements has a control end, a first electrical end and a second electrical end, and the first electrical end is electrically connected to a gate line to couple between a row of LED lamp beads and a switch element of an LED row scanning circuit; a control unit coupled to the second electrical end and configured to transmit an enable voltage to the second electrical end, thereby enabling the shadow elimination voltage establishing element to establish a shadow elimination voltage at a contact point between the switch element and the LED lamp bead; and a voltage adjustment unit coupled to the control end and used to generate an adjustment voltage and transmit it to the control end, so that the voltage at one end of the control end is adjusted to a target voltage. The shadow elimination circuit as described in claim 1, wherein the shadow elimination voltage establishing element is an N-type MOSFET element, and the control terminal, the first electrical terminal and the second electrical terminal are respectively the gate terminal, the drain terminal and the source terminal of the N-type MOSFET element. The shadow cancellation circuit as described in claim 2, wherein the voltage adjustment unit includes a boost circuit for generating the adjustment voltage to be transmitted to the gate terminal of the N-type MOSFET element, thereby increasing a gate terminal voltage of the N-type MOSFET element to the target voltage, and the target voltage is not lower than the sum of a power supply voltage and a critical voltage (Threshold voltage). The blanking circuit as described in claim 3, wherein after the gate voltage is increased to the target voltage, a source-drain voltage of the N-type MOSFET element is between a first voltage and a second voltage. An LED display device comprises: an LED panel, an LED row scanning circuit and at least one LED source driver chip, wherein the LED panel comprises M×N LED lamp beads, M gate lines and N source lines, the LED row scanning circuit comprises M switch elements correspondingly connected to the M gate lines, the LED source driver chip comprises N channel current generators correspondingly connected to the N source lines, and M and N are both positive integers; the LED display device further comprises a shadow elimination circuit, and the shadow elimination circuit comprises: a plurality of shadow elimination voltage establishment elements, wherein each of the shadow elimination voltage establishment elements Each device has a control end, a first electrical end and a second electrical end, and the first electrical end is electrically connected to a gate line to couple between a row of LED lamp beads and a switch element of an LED row scanning circuit; a control unit is coupled to the second electrical end and is configured to transmit an enable voltage to the second electrical end, thereby enabling the blanking voltage establishment element to establish a blanking voltage at a contact point between the switch element and the LED lamp bead; and a voltage adjustment unit is coupled to the control end and used to generate an adjustment voltage and transmit it to the control end, so that the voltage at one end of the control end is adjusted to a target voltage. The LED display device as described in claim 5, wherein the blanking voltage establishing element is an N-type MOSFET element, and the control end, the first electrical end and the second electrical end are respectively the gate end, the drain end and the source end of the N-type MOSFET element. The LED display device as described in claim 6, wherein the voltage adjustment unit includes a boost circuit for generating the adjustment voltage and transmitting it to the gate terminal of the N-type MOSFET element, thereby increasing a gate terminal voltage of the N-type MOSFET element to the target voltage, and the target voltage is not less than the sum of a power supply voltage and a critical voltage (Threshold voltage). An LED display device as described in claim 7, wherein after the gate voltage is increased to the target voltage, a source-drain voltage of the N-type MOSFET element is between a first voltage and a second voltage. The LED display device as described in claim 5, wherein the M×N LED lamp beads are electrically connected to the M gate lines and the N source lines in a common cathode connection manner, and the LED source driver chip is a current source type multi-channel constant current driver chip. The LED display device as described in claim 5, wherein the M×N LED lamp beads are electrically connected to the M gate lines and the N source lines in a common anode connection manner, and the LED source driver chip is a current sink type multi-channel constant current driver chip. An information processing device, characterized in that it includes at least one LED display device as described in any one of claim 5 to claim 10.

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