TWI884807B - Precharge voltage calibration circuit, display driver chip and information processing device - Google Patents

Abstract

The present invention mainly discloses a pre-charge voltage calibration circuit, which is applied to a display driver chip including a pre-charge circuit and a storage module, and mainly includes a trim code adjustment module and a voltage trim unit. The trim code adjustment module is configured to read a first trim code from the storage module, and adjust the first trim code to a second trim code according to a calibration signal. On the other hand, the voltage trim unit is configured to generate a voltage adjustment signal according to the second trim code and transmit it to the pre-charge circuit to trim the pre-charge voltage of the pre-charge circuit to a target pre-charge voltage. It is worth noting that, taking the calibration signal as a 3-bit code as an example, the 3-bit code can be changed successively to gradually adjust the pre-charge voltage so that it approaches the target pre-charge voltage.

Description

Precharge voltage calibration circuit, display driver chip and information processing device

The present invention relates to the technical field of LED display, and more particularly to a pre-charge voltage calibration circuit integrated into an LED display driver chip for calibrating the pre-charge voltage (Vpre) built into the chip.

FIG1 is a basic structure diagram of a known LED display. As shown in FIG1 , the known LED display 1a mainly includes: an LED display panel 11a and a display driver chip 12a, wherein the LED display panel 11a includes M lines and N columns of LED elements, M and N are positive integers, and the display driver chip 12a is an LED constant current driver chip, and therefore includes N current sources (i.e., N source driver modules). It is worth noting that the display driver chip 12a is also provided with a pre-charge circuit 121a. Before the N current sources provide driving current to the N source lines of the LED display panel 11a, the pre-charge circuit is enabled to charge the N LED elements in the same row to a predetermined voltage (Vpre). It should be noted that the LED elements themselves have a parasitic capacitance, so they can be pre-charged. In addition, practical experience shows that the use of pre-charge operation can achieve optimized visual effects on the LED display 1a.

Furthermore, FIG. 2 is a block diagram of a known LED display. As shown in FIG. 2 , a plurality of display driver chips 12a are used in a medium or large-sized LED display 1a, wherein each display driver chip 12a is responsible for driving a display block of the LED display panel 11a. During normal operation, a host computer (such as a laptop) transmits display data and related control signals to a control card 10a, and the control card 10a controls each of the display driver chips 12a to drive the display block for which it is responsible.

According to practical experience, when the preset voltages (Vpre) built into the multiple display driver chips 12a are different, the LED display panel 11a driven by the multiple display driver chips 12a will have obvious color blocks. Therefore, before the chips are shipped, the chip manufacturer will trim the preset voltage of each display driver chip 12a to ensure that all shipped display driver chips 12a have the same preset voltage built into them. Unfortunately, long-term usage data shows that in the process of assembling multiple display driver chips 12a and the LED display panel 11a to form the LED display 1a, the high temperature of welding will cause the predetermined voltage of the display driver chip 12a to drift, resulting in differences in the predetermined voltages of the multiple display driver chips 12a.

In summary, it should be considered to add a calibration circuit for a predetermined voltage in the display driver chip 12a, so that after the client completes the board assembly, the calibration circuit can be run first to uniformly calibrate the predetermined voltage of each display driver chip 12a.

From the above description, it can be seen that a pre-charge voltage calibration circuit is urgently needed in the art.

The main purpose of the present invention is to provide a pre-charge voltage calibration circuit for integration into a display driver chip, to read a first trimming code from a storage module contained in the display driver chip, and then adjust the first trimming code to a second trimming code according to a calibration signal, and generate a voltage adjustment signal according to the second trimming code to transmit to a pre-charge circuit built into the display driver chip, so as to adjust the pre-charge voltage of the pre-charge circuit to a target pre-charge.

Taking the calibration signal as a 3-bit code as an example, the 3-bit code can be changed successively to adjust the pre-charge voltage successively so that it approaches the target pre-charge voltage.

In order to achieve the above-mentioned purpose, the present invention proposes an embodiment of the pre-charge voltage calibration circuit, which is applied to be integrated into a display driver chip, wherein the display driver chip contains a pre-charge circuit and a storage module, and the pre-charge circuit is used to perform a pre-charge operation on a plurality of LED components of an LED display panel according to a pre-charge voltage; the pre-charge voltage calibration circuit includes: A trim code adjustment module, coupled to a calibration signal and the storage module, and configured to read a first trim code from the storage module, and adjust the first trim code to a second trim code according to the calibration signal; and A voltage trimming unit is coupled to the trimming code adjustment module and is configured to generate a voltage adjustment signal according to the second trimming code and transmit it to the pre-charge circuit to trim the pre-charge voltage to a target pre-charge voltage.

In a feasible embodiment, the trimming code adjustment module includes: a control unit coupled to the calibration signal and configured to generate a control signal according to the calibration signal; and an adjustment unit coupled to the control unit and the storage module and configured to adjust the first trimming code read from the storage module to the second trimming code according to the control signal.

In another feasible embodiment, the trimming code adjustment module includes: A control unit coupled to the calibration signal and configured to adjust the first trimming code read from the storage module to the second trimming code according to the calibration signal.

In one embodiment, the calibration signal includes M bits, and the first trimming code and the second trimming code both include N bits; M and N are both positive integers.

Furthermore, the present invention also discloses an embodiment of a display driver chip, which is used to drive an LED display panel, and includes a pre-charge circuit and a storage module, wherein the pre-charge circuit is used to perform a pre-charge operation on a plurality of LED elements of an LED display panel according to a pre-charge voltage; the display driver chip includes a pre-charge voltage calibration circuit, and the pre-charge voltage calibration circuit includes: A trim code adjustment module, coupled to a calibration signal and the storage module, and configured to read a first trim code from the storage module, and adjust the first trim code to a second trim code according to the calibration signal; and A voltage trimming unit is coupled to the trimming code adjustment module and is configured to generate a voltage adjustment signal according to the second trimming code and transmit it to the pre-charge circuit to trim the pre-charge voltage to a target pre-charge voltage.

In a feasible embodiment, the plurality of LED elements are electrically connected to a plurality of gate lines and a plurality of source lines of the LED display panel in a common cathode connection manner, and the display driver chip is a multi-channel constant current driver chip of a current source type.

In one embodiment, the trimming code adjustment module includes: a control unit coupled to the calibration signal and configured to generate a control signal according to the calibration signal; and an adjustment unit coupled to the control unit and the storage module and configured to adjust the first trimming code read from the storage module to the second trimming code according to the control signal.

In another feasible embodiment, the plurality of LED elements are electrically connected to a plurality of gate lines and a plurality of source lines of the LED display panel in a common anode connection manner, and the display driver chip is a current sink type multi-channel constant current driver chip.

In one embodiment, the trim code adjustment module includes: A control unit coupled to the calibration signal and configured to adjust the first trim code read from the storage module to the second trim code according to the calibration signal.

In one embodiment, the calibration signal includes M bits, and the first trimming code and the second trimming code both include N bits; M and N are both positive integers.

Furthermore, the present invention also provides an embodiment of an information processing device, which has at least one LED display, and is characterized in that the LED display has an LED display panel and at least one display driver chip of the present invention as described above.

In one embodiment, the information processing device is an electronic device selected from the group consisting of a TV wall, an electronic billboard, a smart TV, a tablet computer, a laptop computer, an all-in-one computer, an in-vehicle 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 basic structural diagram of an LED display including a pre-charge voltage calibration circuit of the present invention. As shown in FIG3, the LED display 1 mainly includes: an LED display panel 11 and a display driver chip 12, wherein the LED display panel 11 includes X rows and Y columns (i.e., X lines, Y columns) of LED elements, and X and Y are positive integers. On the other hand, FIG4 is a first structural diagram of the LED display panel 11 shown in FIG3. As shown in FIG3 and FIG4, in a feasible embodiment, the X×Y LED elements 111 are electrically connected to the Y gate lines and the X source lines of the LED display panel 11 in a common anode connection manner. Furthermore, the display driver chip 12 is a current sink type multi-channel constant current driver chip, and includes Y current sources 121 and Y first switch elements 122 for adjusting the luminous brightness.

Furthermore, as shown in Figures 3 and 4, the display driver chip 12 includes a pre-charge circuit 12P, and the pre-charge circuit 12P includes a (pre-charge) voltage generating unit 12P0, a pre-charge voltage providing unit 12P1 and Y second switching elements 12P2, wherein the voltage generating unit 12P0 is used to generate a pre-charge voltage (Vpre), and the pre-charge voltage providing unit 12P1 is a voltage follower for transmitting the pre-charge voltage to each second switching element 12P2. During normal operation, before the Y current sources 121 provide driving current to the Y source lines of the LED display panel 11, the pre-charge circuit 12P is enabled to charge the Y LED elements 111 in the same row to the pre-charge voltage (Vpre). It should be noted that the LED element 111 itself has a parasitic capacitor, so it can be pre-charged.

Of course, the LED display panel 11 can also be a common cathode panel. FIG. 5 is a second structural diagram of the LED display panel 11 shown in FIG. 3. As shown in FIG. 3 and FIG. 5, in another feasible embodiment, the X×Y LED elements 111 are electrically connected to the Y gate lines and the X source lines of the LED display panel 11 in a common cathode connection manner. In addition, the display driver chip 12 is a current source type multi-channel constant current driver chip, and includes Y current sources 121 and Y first switch elements 122 for adjusting the luminous brightness.

As shown in FIG3 , the precharge voltage calibration circuit 2 of the present invention is integrated into the display driver chip 12. It is worth noting that when the precharge voltage calibration circuit 2 of the present invention is included, the customer can operate an electronic device (such as a laptop) to transmit a calibration signal to the display driver chip 12. In this way, the pre-charge voltage calibration circuit 2 of the present invention reads a first trim code (Trim code1) from a storage module 120 contained in the display driver chip 12, and then adjusts the first trim code to a second trim code (Trim code2) according to the calibration signal, and generates a voltage adjustment signal according to the second trim code and transmits it to the voltage generating unit 12P0 of the pre-charge circuit 12P to control the voltage generating unit 12P0 to adjust the pre-charge voltage outputted by it to a target pre-charge voltage, wherein the storage module 120 can be a programmable memory, an OTP (one-time programmable memory) or a static random access memory.

FIG6 is a block diagram of a pre-charge voltage calibration circuit of the present invention. As shown in FIG6, the pre-charge voltage calibration circuit 2 of the present invention mainly includes a trimming code adjustment module 21 and a voltage trimming unit 22. According to the design of the present invention, as shown in FIG3 and FIG6, the trimming code adjustment module 21 is coupled to the storage module 120 and a calibration signal sent by the customer operating his electronic device, and is configured to read a first trimming code from the storage module 120, and adjust the first trimming code to a second trimming code according to the calibration signal. On the other hand, the voltage trimming unit 22 is coupled to the trimming code adjustment module 21, and is configured to generate a voltage adjustment signal according to the second trimming code and transmit it to the voltage generating unit 12P0 of the pre-charge circuit 12P, thereby controlling the voltage generating unit 12P0 to adjust its output pre-charge voltage to a target pre-charge voltage.

FIG7 is a first block diagram of the trimming code adjustment module 21 shown in FIG6. As shown in FIG7, in one embodiment, the trimming code adjustment module 21 includes a first control unit 211 and an adjustment unit 212, wherein the control unit 211 is coupled to the calibration signal and is configured to generate a control signal according to the calibration signal. Furthermore, the adjustment unit 212 is coupled to the control unit 211 and the storage module 120 and is configured to adjust the first trimming code read from the storage module 120 to the second trimming code according to the control signal. Specifically, the calibration signal includes M bits (e.g., code[M:0]), and the first trim code and the second trim code both include N bits (e.g., Trim code 1[N:0], Trim code 2[N:0]). As shown in the following table (1), M and N are both positive integers, for example, M=3. Table (1) Calibration signal code[M:0] First adjustment code Second adjustment code 000 Trim code 1[N:0] = Trim code 1[N:0] 001 Trim code 1[N:0] = Trim code 1[N:0]＋1 010 Trim code 1[N:0] = Trim code 1[N:0]＋2 011 Trim code 1[N:0] = Trim code 1[N:0]＋3 100 Trim code 1[N:0] = Trim code 1[N:0] 101 Trim code 1[N:0] = Trim code 1[N:0]－1 110 Trim code 1[N:0] = Trim code 1[N:0]－2 111 Trim code 1[N:0] = Trim code 1[N:0]－3

As shown in the above table (1), taking the calibration signal as a 3-bit code as an example, the customer can operate his electronic device to gradually change the 3-bit code (for example: 000à001à010à011), thereby gradually adjusting the pre-charge voltage, and finally making the pre-charge voltage approach the target pre-charge voltage.

Specifically, when the LED display panel 11 is a common anode panel, if the LED display panel 11 has dark blocks when displaying low grayscale images, it means that the pre-charge voltage (Vpre) built into the display driver chip 12 is too high. At this time, a calibration signal code[2:0]=3'b001 can be sent to the display driver chip 12 to control the trim code adjustment module 21 to add 1 to the first trim code (trim code1[N:0]) read from the storage module 120 to generate a second trim code (trim code2[N:0]). Thus, the voltage trimming unit 22 generates a corresponding voltage adjustment signal according to the second trimming code and transmits it to the voltage generating unit 12P0 to reduce the pre-charge voltage (Vpre) output by the voltage generating unit 12P0, thereby achieving the effect of improving the brightness of the dark block.

If the dark block is still too dark (not bright enough), a calibration signal code[2:0]=3'b010 can be continuously sent to the display driver chip 12 to control the trim code adjustment module 21 to add 2 to the first trim code (trim code1[N:0]) read from the storage module 120 to generate a second trim code (trim code2[N:0]). In this way, the voltage trimming unit 22 generates a corresponding voltage adjustment signal according to the second trim code and transmits it to the voltage generating unit 12P0 to further reduce the pre-charge voltage (Vpre) output by the voltage generating unit 12P0, thereby further improving the brightness of the dark block. Similarly, the pre-charge voltage can be adjusted successively to gradually approach the target pre-charge voltage.

On the other hand, when the LED display panel 11 is a common cathode panel, if the LED display panel 11 has bright blocks when displaying a low grayscale image, it means that the pre-charge voltage (Vpre) built into the display driver chip 12 is too low. At this time, a calibration signal code[2:0]=3'b101 can be sent to the display driver chip 12 to control the trim code adjustment module 21 to perform a subtraction operation on the first trim code (trim code1[N:0]) read from the storage module 120 to generate a second trim code (trim code2[N:0]). Thus, the voltage trimming unit 22 generates a corresponding voltage adjustment signal according to the second trimming code and transmits it to the voltage generating unit 12P0 to increase the pre-charge voltage (Vpre) output by the voltage generating unit 12P0, thereby achieving the effect of reducing the brightness of the bright block.

If the bright block is still too bright (not dark enough), a calibration signal code[2:0]=3'b110 can be continuously sent to the display driver chip 12 to control the trim code adjustment module 21 to perform a subtraction operation on the first trim code (trim code1[N:0]) read from the storage module 120 to generate a second trim code (trim code2[N:0]). In this way, the voltage trimming unit 22 generates a corresponding voltage adjustment signal according to the second trim code and transmits it to the voltage generating unit 12P0 to further increase the pre-charge voltage (Vpre) to achieve the effect of further reducing the brightness of the bright block.

Further, FIG8 is a first block diagram of the trim code adjustment module 21 shown in FIG6. As shown in FIG8, in another embodiment, the trim code adjustment module 21 includes a second control unit 213, which is coupled to the calibration signal and is configured to adjust the first trim code read from the storage module 120 to the second trim code (trim code 1 à trim code 2) according to the calibration signal. In other words, the second control unit 213 has the functions of the aforementioned first control unit 211 and the aforementioned adjustment unit 212 at the same time.

In addition, the programmable memory 120 can be an OTP (one-time programmable memory) or a general storage module.

Thus, the pre-charge voltage calibration circuit of the present invention has been fully and clearly described above; and, from the above, it can be known that the present invention has the following advantages:

(1) The present invention provides a precharge voltage calibration circuit for integration in a display driver chip, for reading a first trimming code from a storage module contained in the display driver chip, and then adjusting the first trimming code to a second trimming code according to a calibration signal, and generating a voltage adjustment signal according to the second trimming code and transmitting it to a precharge circuit built into the display driver chip to adjust the precharge voltage of the precharge circuit to a target precharge. For example, the calibration signal is a 3-bit code, and the 3-bit code can be changed successively to adjust the precharge voltage successively so that it approaches the target precharge voltage.

(2) Furthermore, the present invention also provides a display driver chip for driving an LED display panel comprising X×Y LED elements, wherein the display driver chip contains a pre-charge voltage calibration circuit as described above.

(3) Furthermore, the present invention also provides an information processing device having at least one display device, and characterized in that the LED display has an LED display panel and at least one display driver chip of the present invention as described above. In one 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 aforementioned 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 display panel 12a: Display driver chip 121a: Pre-charge circuit 10a: Control card 1: LED display 11: LED display panel 111: LED component 12: Display driver chip 120: Storage module 121: Current source 122: First switch component 12P: Pre-charge circuit 12P0: Voltage generation unit 12P1: Pre-charge voltage supply unit 12P2: Second switch component 2: Pre-charge voltage calibration circuit 21: Trim code adjustment module 211: First control unit 212: Adjustment unit 213: Second control unit 22: Voltage trimming unit

FIG. 1 is a basic structural diagram of a known LED display; FIG. 2 is a block diagram of a known LED display; FIG. 3 is a basic structural diagram of an LED display including a pre-charge voltage calibration circuit of the present invention; FIG. 4 is a first structural diagram of the LED display panel shown in FIG. 3; FIG. 5 is a second structural diagram of the LED display panel shown in FIG. 3; FIG. 6 is a block diagram of a pre-charge voltage calibration circuit of the present invention; FIG. 7 is a first block diagram of the trim code adjustment module shown in FIG. 6; and FIG. 8 is a second block diagram of the trim code adjustment module shown in FIG. 6.

120: Storage module

12P0: Voltage generating unit

12P1: Pre-charge voltage providing unit

2: Pre-charge voltage calibration circuit

21: Modify the code adjustment module

22: Voltage adjustment unit

Claims (10)

A precharge voltage calibration circuit is used for integration in a display driver chip, wherein the display driver chip contains a precharge circuit and a storage module, and the precharge circuit is used to perform a precharge operation on a plurality of LED components of an LED display panel according to a precharge voltage; the precharge voltage calibration circuit includes: A trim code adjustment module, coupled to a calibration signal and the storage module, and configured to read a first trim code from the storage module, and adjust the first trim code to a second trim code according to the calibration signal; and A voltage trimming unit is coupled to the trimming code adjustment module and is configured to generate a voltage adjustment signal according to the second trimming code and transmit it to the pre-charge circuit to trim the pre-charge voltage to a target pre-charge voltage; Wherein, the trimming code adjustment module includes: a control unit, coupled to the calibration signal, and configured to generate a control signal according to the calibration signal; and an adjustment unit, coupled to the control unit and the storage module, and configured to adjust the first trimming code read from the storage module to the second trimming code according to the control signal. A precharge voltage calibration circuit is used for integration in a display driver chip, wherein the display driver chip contains a precharge circuit and a storage module, and the precharge circuit is used to perform a precharge operation on a plurality of LED components of an LED display panel according to a precharge voltage; the precharge voltage calibration circuit includes: A trim code adjustment module, coupled to a calibration signal and the storage module, and configured to read a first trim code from the storage module, and adjust the first trim code to a second trim code according to the calibration signal; and A voltage trimming unit is coupled to the trimming code adjustment module and is configured to generate a voltage adjustment signal according to the second trimming code and transmit it to the pre-charge circuit to trim the pre-charge voltage to a target pre-charge voltage; Wherein, the trimming code adjustment module includes: A control unit is coupled to the calibration signal and is configured to adjust the first trimming code read from the storage module to the second trimming code according to the calibration signal. A pre-charge voltage calibration circuit as described in claim 1 or 2, wherein the calibration signal comprises M bits, and the first trimming code and the second trimming code both comprise N bits; M and N are both positive integers. A display driver chip is used to drive an LED display panel, and includes a pre-charge circuit and a storage module. The pre-charge circuit is used to perform a pre-charge operation on a plurality of LED elements of an LED display panel according to a pre-charge voltage. The display driver chip includes a pre-charge voltage calibration circuit, and the pre-charge voltage calibration circuit includes: A trim code adjustment module, coupled to a calibration signal and the storage module, and configured to read a first trim code from the storage module, and adjust the first trim code to a second trim code according to the calibration signal; and A voltage trimming unit is coupled to the trimming code adjustment module and is configured to generate a voltage adjustment signal according to the second trimming code and transmit it to the pre-charge circuit to trim the pre-charge voltage to a target pre-charge voltage; Wherein, the trimming code adjustment module includes: a control unit, coupled to the calibration signal, and configured to generate a control signal according to the calibration signal; and an adjustment unit, coupled to the control unit and the storage module, and configured to adjust the first trimming code read from the storage module to the second trimming code according to the control signal. A display driver chip as described in claim 4, wherein the plurality of LED elements are electrically connected to a plurality of gate lines and a plurality of source lines of the LED display panel in a common cathode connection manner, and the display driver chip is a multi-channel constant current driver chip of a current source type. A display driver chip as described in claim 4, wherein the calibration signal comprises M bits, and the first trimming code and the second trimming code both comprise N bits; M and N are both positive integers. A display driver chip as described in claim 4, wherein the plurality of LED elements are electrically connected to a plurality of gate lines and a plurality of source lines of the LED display panel in a common anode connection manner, and the display driver chip is a multi-channel constant current driver chip of a current sink type. A display driver chip is used to drive an LED display panel, and includes a pre-charge circuit and a storage module. The pre-charge circuit is used to perform a pre-charge operation on a plurality of LED elements of an LED display panel according to a pre-charge voltage. The display driver chip includes a pre-charge voltage calibration circuit, and the pre-charge voltage calibration circuit includes: A trim code adjustment module, coupled to a calibration signal and the storage module, and configured to read a first trim code from the storage module, and adjust the first trim code to a second trim code according to the calibration signal; and A voltage trimming unit is coupled to the trimming code adjustment module and is configured to generate a voltage adjustment signal according to the second trimming code and transmit it to the pre-charge circuit to trim the pre-charge voltage to a target pre-charge voltage; Wherein, the trimming code adjustment module includes: A control unit is coupled to the calibration signal and is configured to adjust the first trimming code read from the storage module to the second trimming code according to the calibration signal. A display driver chip as described in claim 8, wherein the calibration signal comprises M bits, and the first trimming code and the second trimming code both comprise N bits; M and N are both positive integers. An information processing device has at least one LED display, wherein the LED display has an LED display panel and at least one display driver chip as described in any one of claims 4 to 9.

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