TWI854716B - Display device and information processing device - Google Patents

Abstract

The present invention discloses a source drive circuit, which is integrated into a display driver chip and includes: a shift register, a data register, a data latch, a level shifter, a plurality of digital-to-analog converters (DACs), and a plurality of buffer amplifiers. In particular, the present invention designs the buffer amplifier to be biased between a first analog voltage and a second analog voltage, and to have a voltage difference between the two analog voltages. For example, the voltage difference △V<1.2V (i.e., gamma range). In this way, when designing the circuit, low-voltage-tolerant MSFET elements can be used to form the buffer amplifier. Since low-voltage MOSFET components are less prone to component mismatch, the input offset voltage error between the multiple buffer amplifiers can be improved. At the same time, since the voltage difference is reduced, the chip power consumption of the display driver chip is also reduced.

Description

Display device and information processing device

The present invention relates to the technical field of flat panel display devices, and in particular to a display device comprising at least two circuits electrically connected to each other using flexible circuit board bonding (FPC bonding).

It is known that flat panel displays include non-self-luminous flat panel displays and self-luminous flat panel displays, wherein liquid crystal displays are a type of non-self-luminous flat panel displays that have been used for a long time, while organic light-emitting diode (OLED) displays and light-emitting diode (LED) displays are self-luminous flat panel displays that are currently in mainstream applications. FIG1 is a block diagram of a known OLED display device. As shown in FIG1 , the known OLED display device 1a mainly includes: an OLED panel 11a, a display controller (Tcon) 120a, a gate driver unit 121a, a source driver unit 122a, and an EM control unit 123a, wherein the OLED panel 11a includes X×Y pixel circuits 111a and X×Y OLED elements 112a, and X and Y are positive integers.

Furthermore, FIG. 2 is a circuit topology diagram of the pixel circuit shown in FIG. 1. As shown in FIG. 2, the pixel circuit 111a can be composed of 7 TFT elements and a storage capacitor, and the pixel circuit 111a is biased between a first operating voltage ELVDD and a second operating voltage ELVSS. For example, ELVDD = 7V, and ELVSS = 0V. In other words, when designing the circuit, high-voltage-resistant thin-film transistor elements must be used as the 7 TFT elements. However, practical experience has shown that high-voltage-resistant thin-film transistor elements are more likely to have element mismatch, resulting in a difference in threshold voltage (Vth) between different transistors, which ultimately causes uneven luminance of the OLED element 112a. On the other hand, it is well known that the OLED element 112a will age over time. Therefore, practical experience also indicates that if a plurality of high-voltage-resistant thin-film transistor elements are used to form the pixel circuit 111a, the aging of the OLED element 112a will be accompanied by the problem of increased element cross-voltage. In summary, the known source drive unit 122a still has room for further improvement.

On the other hand, FIG3 is a circuit block diagram of the source drive unit shown in FIG1. As shown in FIG3, the conventional source drive unit 122a includes: a shift register 1221a, a data register 1222a, a data latch 1223a, a level shifter 1224a, a plurality of digital-to-analog converters (DAC) 1225a, and a plurality of buffer amplifiers 1226a. It should be known that the buffer amplifier 1226a is composed of a plurality of MOSFET elements and is biased between an analog working voltage AVDD and a ground voltage GND, such as 8V to 0V. In other words, when designing the circuit, a plurality of high-voltage MOSFETs must be used to form the buffer amplifier 1226a. However, practical experience indicates that high-voltage MOSFET components are more likely to have component mismatch, which results in the buffer amplifier 1226a having inconsistent input offset voltages, causing the plurality of OLED components 112a coupled to the plurality of buffer amplifiers 1226a to have different OLED currents, thereby causing uneven luminous brightness.

At present, the display controller (Tcon) 120a, the source driver unit 122a and the light-emitting control unit 123a shown in FIG. 1 can be integrated into a display driver chip, and the gate driver unit 121a can be integrated into the OLED panel 11a using the GOA technology. Therefore, practical experience also points out that the 8V-0V analog operating voltage AVDD will cause the chip power consumption of the display driver chip to be unable to be effectively reduced. In summary, the known source driver unit 122a still has room for further improvement.

From the above description, it can be seen that a new source drive circuit and display device are urgently needed in the field.

The main purpose of the present invention is to provide a source drive circuit, which is integrated into a display driver chip and includes: a shift register, a data register, a data latch, a level shifter, a plurality of digital-to-analog converters (DACs), and a plurality of buffer amplifiers. In particular, the buffer amplifier is designed by the present invention to be biased between a first analog voltage and a second analog voltage, and to have a voltage difference between the two analog voltages. For example, the voltage difference ΔV is less than 1.2V (i.e., gamma range). In this way, when designing the circuit, low-voltage-tolerant MSFET elements can be used to form the buffer amplifier. Since low voltage MOSFET components are less likely to have component mismatch, the input offset voltage error between the plurality of buffer amplifiers can be improved. At the same time, since the voltage difference is reduced, the chip power consumption of the display driver chip is also reduced.

To achieve the above-mentioned purpose, the present invention proposes an embodiment of the source drive circuit, which includes: a shift register, a data register, a data latch, a level shifter, a plurality of digital-to-analog converters (DACs), and a plurality of buffer amplifiers; its characteristic is that the buffer amplifier is biased between a first analog voltage and a second analog voltage, the second analog voltage is greater than 0V, and there is a voltage difference between the first analog voltage and the second analog voltage.

In one embodiment, the voltage difference is less than 8V.

In one embodiment, the buffer amplifier includes a plurality of MOSFET elements, and each of the MOSFET elements is selected from any one of the group consisting of medium-high voltage MOSFET elements, medium-voltage MOSFET elements, medium-low voltage MOSFET elements, and low voltage MOSFET elements.

Furthermore, the present invention also proposes a display device, including a display panel and at least one display driver chip, wherein the display panel includes a plurality of X×Y pixel circuits and X×Y light-emitting elements, X and Y are positive integers, and the display driver chip has a source driver circuit including: a shift register, a data register, a data latch, a level shifter, a plurality of digital-to-analog converters (DACs), and a plurality of buffer amplifiers; the characteristics are: The buffer amplifier is biased between a first analog voltage and a second analog voltage, the second analog voltage is greater than 0V, and there is a first voltage difference between the first analog voltage and the second analog voltage; and The pixel circuit is biased between a first operating voltage and a second operating voltage, the second operating voltage is greater than 0V, and there is a second voltage difference between the first operating voltage and the second operating voltage.

In one embodiment, the first operating voltage is less than the first analog voltage.

In one embodiment, the first voltage difference and the second voltage difference are both less than 8V.

In one embodiment, the buffer amplifier includes a plurality of MOSFET elements, and each of the MOSFET elements is selected from any one of the group consisting of medium-high voltage MOSFET elements, medium-voltage MOSFET elements, medium-low voltage MOSFET elements, and low voltage MOSFET elements.

In one embodiment, the pixel circuit includes a plurality of TFT elements and at least one storage capacitor, and each of the TFT elements is selected from any one of the groups consisting of medium-high voltage resistant TFT elements, medium-voltage resistant TFT elements, medium-low voltage resistant TFT elements, and low voltage resistant TFT elements.

Furthermore, the present invention also provides an information processing device, which is characterized by comprising the display device of the present invention as described above. Moreover, in a feasible embodiment, the information processing device is an electronic device selected from the group consisting of a head-mounted display device, a smart TV, a smart phone, a smart watch, a tablet computer, an all-in-one computer, a notebook computer, a car entertainment device, a digital camera, and a video door machine.

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.

FIG. 4 is a block diagram of a display device including a source driving circuit of the present invention. As shown in FIG. 4 , the display device 1 mainly includes: a display panel 11 and at least one display driver chip 12 , where the display panel 11 can be but is not limited to an OLED panel, an LED panel, a Micro-LED panel, or a QLED panel. , and includes X×Y pixel circuits 111 and X×Y light-emitting elements 112, X and Y are positive integers, and the display driving chip 12 contains the source driving circuit 122 of the present invention. Further, FIG. 5 is a block diagram of the source driving circuit shown in FIG. 4 . As shown in FIG. 4 , in one embodiment, the source driving circuit 122 includes: a shift register 1221, a data register 1222, a data latch 1223, a level shifter 1224, a plurality of digital-to-analog converters A DAC 1225 and a plurality of buffer amplifiers 1226 are provided, wherein the buffer amplifiers 1226 are biased between a first analog voltage AVDD and a second analog voltage AVSS.

FIG6 is a voltage level diagram of the first analog voltage AVDD and the second analog voltage AVSS shown in FIG5 . As shown in FIG5 and FIG6 , the second analog voltage AVSS is greater than the ground voltage (i.e., 0V), and there is a first voltage difference ΔV1 between the first analog voltage AVDD and the second analog voltage AVSS. According to the design of the present invention, the first voltage difference ΔV1 is less than 8V, 5V, 3V, or 1.2V. Specifically, the buffer amplifier 1226 includes a plurality of MOSFET elements, and each of the MOSFET elements can be a medium-high voltage MOSFET element, a medium-voltage MOSFET element, a medium-low voltage MOSFET element, or a low-voltage MOSFET element. In other words, the present invention does not use high-voltage MOSFET elements to form the buffer amplifier 1226. For example, medium-high voltage MOSFET elements can be used to form the buffer amplifier 1226, and in this case, the first voltage difference ΔV1 is less than 8V. In addition, if the buffer amplifier 1226 is composed of medium-voltage MOSFET elements, the first voltage difference ΔV1 is less than 5V. Further, if the buffer amplifier 1226 is composed of medium-low voltage MOSFET elements, the first voltage difference ΔV1 is less than 3V. Furthermore, if the buffer amplifier 1226 is composed of low-voltage MOSFET elements, the first voltage difference ΔV1 is less than 1.2V.

It is reiterated that the prior art usually adopts multiple high-voltage MOSFET elements to form the buffer amplifier 1226. However, the high-voltage MOSFET elements are more prone to element mismatch, which causes the buffer amplifier 1226 to have inconsistent input offset voltages, causing the multiple light-emitting elements 112 coupled to the multiple buffer amplifiers 1226 to have different element currents, thereby causing uneven light brightness. Therefore, the present invention uses a medium-high voltage MOSFET element, a medium-voltage MOSFET element, a medium-low voltage MOSFET element, or a low-voltage MOSFET element to form the buffer amplifier 1226, and adjusts the first voltage difference between the first analog voltage AVDD and the second analog voltage AVSS accordingly according to the type of the selected MOSFET element. For example, the buffer amplifier 1226 is composed of a low-voltage MOSFET element, and the first voltage difference ΔV1 is less than 1.2V (i.e., gamma range). In this way, since the low-voltage MOSFET element is less likely to have a component mismatch phenomenon, the error of the input offset voltage between the plurality of buffer amplifiers 1226 can be improved. At the same time, since the voltage difference between AVDD and AVSS becomes smaller, the chip power consumption of the display driver chip 12 is also reduced synchronously.

Furthermore, FIG. 7 is a circuit topology diagram of the pixel circuit shown in FIG. 4 . As shown in FIG. 7 , the pixel circuit 111 can be composed of 7 TFT elements and a storage capacitor, that is, a 7T1C structure. Of course, in a feasible embodiment, the pixel circuit 111 can also be, but not limited to, a 5T1C structure, a 6T1C structure, and an 8T1C structure. According to the design of the present invention, the pixel circuit 111 is biased between a first operating voltage ELVDD and a second operating voltage ELVSS, wherein the first operating voltage ELVDD is less than the first analog voltage AVDD, the second operating voltage ELVSS is greater than the ground voltage (that is, 0V), and there is a second voltage difference ΔV2 between the first operating voltage ELVDD and the second operating voltage ELVSS.

FIG8 is a voltage level diagram of the first operating voltage ELVDD and the second operating voltage ELVSS shown in FIG7. As shown in FIG7 and FIG8, according to the design of the present invention, the second voltage difference ΔV2 is less than 8V, 5V, 3V, or 1.2V. Specifically, the pixel circuit 111 includes a plurality of TFT elements and at least one storage capacitor, and each of the TFT elements can be a medium-high voltage MOSFET element, a medium-voltage TFT element, a medium-low voltage TFT element, or a low-voltage TFT element. In other words, the present invention does not use high-voltage TFT elements to form the pixel circuit 111. For example, medium-high voltage TFT elements can be used to form the pixel circuit 111, and in this case, the second voltage difference ΔV2 is less than 8V. In addition, if the pixel circuit 111 is composed of a medium voltage TFT element, the second voltage difference ΔV2 is less than 5 V. Furthermore, if the pixel circuit 1116 is composed of a medium-low voltage TFT element, the second voltage difference ΔV2 is less than 3 V. Furthermore, if the pixel circuit 111 is composed of a low voltage TFT element, the second voltage difference ΔV2 is less than 1.2 V.

The prior art generally uses a plurality of high-voltage TFT elements to form the pixel circuit 111. However, the high-voltage TFT elements are more likely to have element mismatch, which results in a difference in threshold voltage (Vth) between different transistors, and ultimately causes uneven brightness of the X×Y light-emitting elements 112. Therefore, the present invention uses medium-high voltage TFT elements, medium-voltage TFT elements, medium-low voltage TFT elements, or low-voltage TFT elements to form the pixel circuit 111, and adjusts the second voltage difference between the first operating voltage ELVDD and the second operating voltage ELVSS accordingly according to the type of the selected TFT element. For example, the pixel circuit 11126 is composed of low-voltage TFT elements, and the second voltage difference ΔV2 < 1.2 V. In this way, since low-voltage TFT elements are less likely to have element mismatch, the difference in threshold voltage (Vth) between different transistors can be improved.

Thus, the source driving 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 discloses a source drive circuit, which is integrated into a display driver chip and includes: a shift register, a data register, a data latch, a level shifter, a plurality of digital-to-analog converters (DACs), and a plurality of buffer amplifiers. In particular, the present invention designs the buffer amplifier to be biased between a first analog voltage and a second analog voltage, and to provide a voltage difference between the two analog voltages. For example, the voltage difference ΔV is less than 1.2V (i.e., gamma range). Thus, when designing the circuit, low-voltage-tolerant MSFET elements can be used to form the buffer amplifier. Since low voltage MOSFET components are less likely to have component mismatch, the input offset voltage error between the plurality of buffer amplifiers can be improved. At the same time, since the voltage difference is reduced, the chip power consumption of the display driver chip is also reduced.

(2) The present invention also discloses a display device, which includes a display panel and at least one display driver chip, wherein the display panel includes a plurality of X×Y pixel circuits and X×Y light-emitting elements, and the display driver chip contains the source driver circuit of the present invention as described above. In addition, the present invention designs the pixel circuit to be biased between a first operating voltage and a second operating voltage, and to have a voltage difference between the two operating voltages. For example, the voltage difference ΔV＜1.2V. In this way, when designing the circuit, a low-voltage-resistant TFT element can be used to form the pixel circuit. Furthermore, since low-voltage TFT elements are less prone to element mismatch, the difference in threshold voltage between different transistors can be improved.

(3) In addition, the present invention also provides an information processing device, which is characterized by comprising the 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 head-mounted display device, a smart TV, a smart phone, a smart watch, a tablet computer, an all-in-one computer, a laptop computer, a car entertainment device, a digital camera, and a video door phone.

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 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.

1a: OLED display device 11a: OLED panel 111a: pixel circuit 112a: OLED element 120a: display controller 121a: gate driver unit 122a: source driver unit 1221a: shift register 1222a: data register 1223a: data latch 1224a: level shifter 1225a: digital-to-analog converter 1226a: buffer amplifier 123a: light-emitting control unit 1: display device 11: display panel 111: pixel circuit 112: light-emitting element 12: display driver chip 122: source driver circuit 1221: shift register 1222: data register 1223: data latch 1224: level shifter 1225: digital-to-analog converter 1226: buffer amplifier

FIG. 1 is a block diagram of a known OLED display device; FIG. 2 is a circuit topology diagram of the pixel circuit shown in FIG. 1; FIG. 3 is a circuit block diagram of the source drive unit shown in FIG. 1; FIG. 4 is a block diagram of a display device including a source drive circuit of the present invention; FIG. 5 is a block diagram of the source drive circuit shown in FIG. 4; FIG. 6 is a voltage level diagram of the first analog voltage and the second analog voltage shown in FIG. 5; FIG. 7 is a circuit topology diagram of the pixel circuit shown in FIG. 4; and FIG. 8 is a voltage level diagram of the first operating voltage and the second operating voltage shown in FIG. 7.

122: Source drive circuit

1221: Shift register

1222: Data register

1223: Data lock register

1224:Level shifter

1225: Digital to Analog Converter

1226: Buffer amplifier

Claims (7)

A display device includes a display panel and at least one display driver chip, wherein the display panel includes a plurality of X×Y pixel circuits and X×Y light-emitting elements, X and Y are positive integers, and the display driver chip includes: a shift register, a data register, a data latch, a level shifter, a plurality of digital-to-analog converters (DACs), and a plurality of buffer amplifiers (Buffer A source drive circuit of an amplifier); characterized in that: the buffer amplifier is biased between a first analog voltage and a second analog voltage, the second analog voltage is greater than 0V, and there is a first voltage difference between the first analog voltage and the second analog voltage; and the pixel circuit is biased between a first operating voltage and a second operating voltage, the second operating voltage is greater than 0V, and there is a second voltage difference between the first operating voltage and the second operating voltage. A display device as described in claim 1, wherein the first operating voltage is less than the first analog voltage. A display device as described in claim 1, wherein the first voltage difference and the second voltage difference are both less than 8V. A display device as described in claim 1, wherein the buffer amplifier includes a plurality of MOSFET elements, and each of the MOSFET elements is selected from any one of the groups consisting of medium-high voltage MOSFET elements, medium-voltage MOSFET elements, medium-low voltage MOSFET elements, and low voltage MOSFET elements. A display device as described in claim 1, wherein the pixel circuit includes a plurality of TFT elements and at least one storage capacitor, and each of the TFT elements is selected from any one of the group consisting of a medium-high voltage TFT element, a medium-voltage TFT element, a medium-low voltage TFT element, and a low voltage TFT element. An information processing device, characterized in that it includes a display device as described in any one of claim 1 to claim 5. The information processing device as described in claim 6, wherein the information processing device is an electronic device selected from the group consisting of a head-mounted display device, a smart TV, a smart phone, a smart watch, a tablet computer, an all-in-one computer, a laptop computer, an in-vehicle entertainment device, a digital camera, and a video door phone.

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