TWI809910B - Display device and impedance adjustment method thereof - Google Patents

Abstract

A display device and impedance adjustment method thereof are provided. The display device includes a display panel, a scan driver and an impedance adjustment circuit. The display panel has a plurality of light emitting elements. The plurality of light emitting elements are arranged in a plurality of display columns and a plurality of display rows. The scan driver is configured to receive an image signal and generate a plurality of driving signals to drive the plurality of light emitting elements according to a plurality of display information of the image signal. The display information is configured to record the number of light emitting elements in the plurality of display columns that need to be illuminated. The impedance adjustment circuit is configured to adjust an impedance of the impedance adjustment circuit according to the plurality of display information of the image signal.

Description

Display device and impedance adjustment method thereof

The present invention relates to a display device, and in particular to a display device and an impedance adjustment method thereof.

In a conventional display device, when the scan driver scans each display column in the display panel column by column, the number of light-emitting elements that need to be turned on in each display column is usually different according to the requirements of the display screen. . At this time, the constant current driving circuit will also generate the same or different currents to the light-emitting elements that are turned on and the corresponding switches of the scan driver.

For example, in the process of displaying a picture, when the number of light-emitting elements that need to be turned on in the corresponding display column is small, the constant current driving circuit will provide a relatively small current to the light-emitting elements that are turned on and the corresponding switch of the scan driver. And when the number of light-emitting elements to be turned on in the corresponding display column is large, the constant current driving circuit will provide a relatively large current to the turned-on light-emitting elements and the corresponding switch of the scan driver.

Compared with the case where the number of light-emitting elements that need to be lit in the corresponding display column is small, when the number of light-emitting elements that need to be lit in the corresponding display column is large, the voltage across the switch of the scan driver It will be increased by the influence of the large current and the internal impedance of the switch, and then the time for the light-emitting elements in the corresponding display column to reach the target potential that can be turned on will be prolonged.

That is to say, in the case that the number of light-emitting elements in each display column may be different, the voltage across each switch in the scan driver will also have different voltage variations, which will cause each The time for the light-emitting element corresponding to a switch to reach the target potential to be turned on will also be different, thereby affecting the quality of the display image.

In view of this, how to effectively reduce the variation of the cross-voltage voltage of the switch of the corresponding scan driver to improve the display quality when the number of light-emitting elements that need to be lit in each display column is different will be relevant in this field. Important subject for technicians.

The invention provides a display device and an impedance adjustment method thereof, which can effectively reduce the variation of the cross-voltage voltage of the switch of the corresponding scan driver, so as to improve the quality of the display screen.

The display device of the present invention includes a display panel, a scan driver and an impedance adjustment circuit. The display panel has a plurality of light emitting elements. A plurality of light emitting elements are arranged into a plurality of display columns and a plurality of display rows. The scan driver is coupled to the display panel. The scanning driver is used to receive the image signal, and generate a plurality of driving signals to drive a plurality of light-emitting elements according to a plurality of display information of the image signal, wherein the plurality of display information is used to record a plurality of light-emitting elements in a plurality of display columns to be clicked amount of light. The impedance adjustment circuit is coupled to the scan driver. The impedance adjustment circuit is used for adjusting the impedance of the impedance adjustment circuit according to a plurality of display information of the image signal.

The impedance adjustment method of a display device of the present invention includes: providing a display panel having a plurality of light-emitting elements arranged in a plurality of display columns and a plurality of display rows; causing the scan driver to receive an image signal, and generate a plurality of display information according to the image signal A plurality of driving signals are used to drive a plurality of light-emitting elements, wherein a plurality of display information is used to record the number of light-up of the plurality of light-emitting elements in a plurality of display rows; Adjust the impedance of the impedance adjustment circuit.

Based on the above, in the display device and the impedance adjustment method thereof according to the embodiments of the present invention, the impedance adjustment circuit can adjust the impedance between the switch circuit and the impedance adjustment circuit according to the lighting requirements of the light-emitting elements of each display column. In this way, when the number of light-emitting elements (or scanning current) that need to be lit in the scanned display column is increased, the variation of the cross-voltage voltage between the switch circuit and the impedance adjustment circuit can be effectively reduced, and The time for each light-emitting element to be turned on to reach the target potential that can be turned on is shortened, thereby prompting the display quality of the display panel.

The term "coupled (or connected)" used throughout the specification of this case (including the scope of claims) may refer to any direct or indirect means of connection. For example, if it is described in the text that a first device is coupled (or connected) to a second device, it should be interpreted that the first device can be directly connected to the second device, or the first device can be connected to the second device through other devices or certain A connection means indirectly connected to the second device. In addition, wherever possible, elements/components/steps with the same reference numerals are used in the drawings and embodiments to represent the same or similar parts. Elements/components/steps using the same symbols or using the same terms in different embodiments can refer to related descriptions.

FIG. 1 is a schematic diagram of a display device according to an embodiment of the invention. Referring to FIG. 1 , the display device 100 includes a display panel 110 , a scan driver 120 , an impedance adjustment circuit 130 and a constant current driving circuit 140 . In this embodiment, the display panel 110 has a plurality of light emitting elements D11˜DNM. These light emitting elements D11-DNM can be arranged into a plurality of display columns S1-SN and a plurality of display rows CH1-CHN. Wherein, the light emitting elements D11 - DNM may be, for example, organic light emitting diodes (Organic Light Emitting Diode, OLED), light emitting diodes (LED) or other light emitting elements, and the present invention is not particularly limited.

The constant current driving circuit 140 includes a plurality of current sinks Iout1˜IoutN. The current sinks Iout1˜IoutN are coupled to the power voltage VCC and the light emitting elements in the display rows CH1˜CHN. The current sinks Iout1˜IoutN can respectively generate the same or different currents to the corresponding light-emitting elements and switches of the switch circuit 121 according to the image signal IM.

In this embodiment, the scan driver 120 is coupled to a plurality of light emitting elements D11˜DNM in the display columns S1˜SN. The scan driver 120 includes a switch circuit 121 and an image processing circuit 122 . Wherein, the switch circuit 121 is coupled between the image processing circuit 122 and the plurality of light emitting elements D11˜DNM. The impedance adjustment circuit 130 is coupled between the switch circuit 121 , the image processing circuit 122 and the reference ground terminal VSS.

In particular, in the embodiment shown in FIG. 1 , the currents generated by the current sinks Iout1 ˜ IoutN can be the same, and the currents flowing through the switch circuit 121 and the impedance adjustment circuit 130 can be represented by the scanning current Iscan. Wherein, the current magnitude of the scanning current Iscan may be related to the number of light-emitting elements to be lit and the magnitude of the current generated by the constant current driving circuit 140 .

For example, when the number of light-emitting elements that need to be turned on in each display column is relatively small, the constant current drive circuit 140 will generate a relatively small current to the light-emitting elements that are turned on. At this time, the current flows through the switch circuit 121 and the scan current Iscan of the impedance adjustment circuit 130 are also relatively small. When the number of light-emitting elements that need to be lit in each display column is relatively large, the constant current drive circuit 140 will generate a relatively large current to the light-emitting elements that are lit. At this time, the current flows through the switch circuit 121 and the impedance adjustment The scan current Iscan of the circuit 130 is also relatively large.

In addition, in this embodiment, the impedances of the switch circuit 121 and the impedance adjustment circuit 130 can be represented by impedance Rdson and impedance Radj respectively. The impedance between the switch circuit 121 and the impedance adjustment circuit 130 can be represented by an impedance Rdrop (ie, Rdrop=Rdson+Radj). The voltage between the switch circuit 121 and the impedance adjustment circuit 130 can be represented by a cross voltage Vdrop (ie, Vdrop=Iscan*Rdrop).

Specifically, in this embodiment, the image processing circuit 122 can receive the scan signal SS and the image signal IM. Wherein, the image signal IM may include a plurality of display information. Each display information can record the number of light-emitting elements that need to be turned on in each display row S1 -SN according to the display requirement of the display panel 110 .

The image processing circuit 122 can obtain a switching signal according to the scan signal SS, and scan the plurality of display columns S1 -SN in the display panel 110 column by column according to the switching signal. The image processing circuit 122 can generate the driving signals DS1 -DSN to the switch circuit 121 according to the image signal IM based on the switching signal. The image processing circuit 122 and the constant current driving circuit 140 can light up one or more light emitting elements in the corresponding display row according to the display information of the image signal IM.

For example, assuming that the scan driver 120 scans the display row S1 according to the switching signal, and the display information of the image signal IM indicates that one light emitting element (for example, D11 ) in the display row S1 needs to be turned on, then At this time, the image processing circuit 122 can generate the driving signal DS1 to the switch circuit 121 according to the image signal IM, so as to turn on the switch corresponding to the display row S1 in the switch circuit 121, and drive the light emitting element D11 through the driving signal DS1. Moreover, the current sink Iout1 of the constant current driving circuit 140 can generate current to the light emitting element D11 according to the image signal IM.

In the above situation, after the image processing circuit 122 receives the image signal IM, the image processing circuit 122 can perform data conversion on the display information of the image signal IM, so as to meet the lighting requirement of the display panel 110 (that is, it needs to scan Displays the impedance adjustment signal of the number of light-emitting elements D11 when column S1 is lit. Next, the image processing circuit 122 can retrieve the first part of bits A1 - A3 of the impedance adjustment signal, and provide the first part of bits A1 - A3 of the impedance adjustment signal to the impedance adjustment circuit 130 .

Wherein, in this embodiment, the first part of bits A1 - A3 may be, for example, 3 most significant bits (Most Significant Bit, MSB) of the impedance adjustment signal, but the present invention is not particularly limited.

Next, the impedance adjustment circuit 130 can adjust the impedance Radj of the impedance adjustment circuit 130 to a first impedance value Radj1 according to the first part of bits A1 - A3 of the impedance adjustment signal.

According to the above example, it can be known that only one light-emitting element (for example, D11) needs to be turned on in the display column S1 and the current value of the scanning current Iscan is assumed to be 5mA, the switch circuit 121 and the impedance adjustment circuit 130 The voltage across Vdrop between can be: Vdrop=Iscan*Rdrop=5mA*(Rdson+Radj1)...(1)

On the other hand, assume that the scan driver 120 scans the display row S2 according to the switching signal, and the display information of the image signal IM indicates that 60 light-emitting elements (for example, D21˜D260) in the display row S2 need to be clicked. On, at this time, the image processing circuit 122 can generate the driving signal DS2 to the switch circuit 121 according to the image signal IM, so as to turn on the switch corresponding to the display row S2 in the switch circuit 121, and drive the light emitting elements D21-D260 through the driving signal DS2 . Moreover, the current sinks Iout1˜Iout60 of the constant current driving circuit 140 can generate current to the light emitting elements D21˜D260 according to the image signal IM.

Under the above circumstances, the image processing circuit 122 can obtain the lighting requirements of the display panel 110 according to the display information of the image signal IM (that is, the number of light-emitting elements D21-D260 that need to be turned on when the display row S2 is scanned). Impedance adjustment signal. Next, the image processing circuit 122 can retrieve the first part of bits A1 - A3 of the impedance adjustment signal, and provide the first part of bits A1 - A3 of the impedance adjustment signal to the impedance adjustment circuit 130 .

Next, the impedance adjustment circuit 130 can adjust the impedance Radj of the impedance adjustment circuit 130 to a second impedance value Radj2 smaller than the first impedance value Radj1 according to the first part of bits A1 - A3 of the impedance adjustment signal.

According to the above example, it can be known that in the display column S2 there are 60 light-emitting elements (for example, D21-D260) that need to be lit and the current value of the scanning current Iscan is assumed to be 300mA, the switch circuit 121 and the impedance adjustment circuit The cross voltage Vdrop between 130 can be: Vdrop=Iscan*Rdrop=300mA*(Rdson+Radj2)…..(2)

According to the example description of the above formula (1) and formula (2), it can be known that in this embodiment, when the number of light-emitting elements that need to be lit in the scanned display column is small, the impedance adjustment circuit 130 The magnitude of the impedance Radj of the impedance adjustment circuit 130 (ie, the first impedance value Radj1 ) can be increased according to the display information of the image signal IM. In contrast, when the number of light-emitting elements to be turned on in the scanned display row is large, the impedance adjustment circuit 130 can lower the impedance Radj of the impedance adjustment circuit 130 according to the display information of the image signal IM (that is, The second impedance value Radj2).

That is to say, the impedance adjustment circuit 130 of this embodiment can adjust the impedance Rdrop between the switch circuit 121 and the impedance adjustment circuit 130 according to the lighting requirement of the light emitting elements of each display row. In this way, when the number of light-emitting elements (or scanning current Iscan) to be turned on in the scanned display column is increased, the change amount of the voltage across the voltage Vdrop between the switch circuit 121 and the impedance adjustment circuit 130 can be effectively is reduced, and shortens the time for each light-emitting element to be turned on to reach the target potential that can be turned on, thereby prompting the display quality of the display panel 110 .

FIG. 2 is a schematic diagram of a scan driver and an impedance adjustment circuit according to the embodiment of FIG. 1 . Please refer to FIG. 1 and FIG. 2 at the same time. In this embodiment, the switch circuit 121 includes a plurality of switches SW11 - S1N, wherein these switches SW11 - S1N may be N-type transistors as an example. The switches SW11˜S1N are respectively coupled to a plurality of light emitting elements of the display columns S1˜SN. Wherein, the currents flowing through the switches SW11˜S1N can be represented by scanning currents Iscan11˜Iscan1N respectively.

In this embodiment, the image processing circuit 122 includes a controller 123 , a memory 124 , a data converter 125 and a multiplexer 126 . The controller 123 is coupled to the plurality of switches SW11 - S1N of the switch circuit 121 . The memory 124 is coupled to the data converter 125 . The multiplexer 126 is coupled between the data converter 125 and the impedance adjustment circuit 130 . Wherein, the data converter 125 of this embodiment may be, for example, a decoder.

In this embodiment, the impedance adjustment circuit 130 includes a standard resistor RT, a plurality of resistors R1-R3, and a plurality of switches SW21-SW23. The standard resistor RT is coupled between the switch circuit 121 and the reference ground terminal VSS. The resistors R1 - R3 are respectively coupled between the switch circuit 121 and the corresponding switches SW21 - SW23 . Wherein, these switches SW21-S23 may be N-type transistors as an example. Moreover, the number of switches and resistors of the impedance adjustment circuit 130 can be adjusted according to design requirements, and the present invention is not limited to the three switches and four resistors shown in FIG. 2 .

Regarding the implementation details of the display device 100 , in detail, in this embodiment, the controller 123 can receive the scan signal SS and the image signal IM. The controller 123 can obtain the switching signal RS according to the scanning signal SS, and scan the plurality of display columns S1˜SN in the display panel 110 column by column according to the switching signal RS.

The controller 123 can generate the driving signals DS1˜DSN to the switches SW11˜SW1N according to the image signal IM based on the switching signal RS. The switches SW11˜SW1N can be turned on respectively according to the driving signals DS1˜DSN, and drive the light emitting elements through the corresponding driving signals DS1˜DSN.

On the other hand, the memory 124 of this embodiment can store a plurality of display information DIF1˜DIFN of the image signal IM. Wherein, Table (1) shows a plurality of display information DIF1 - DIFN of the image signal IM. Each display information DIF1-DIFN can record the number of light-emitting elements that need to be turned on in each display row S1-SN according to the display requirement of the display panel 110 . Wherein, the mark "1" indicates that the light-emitting elements on the corresponding display columns and rows need to be turned on, and the mark "0" indicates that the light-emitting elements on the corresponding display columns and display rows do not need to be turned on. CH1 CH2 … CHN quantity display information S1 1 0 … 1 12 DIF1 S2 0 1 … 1 48 DIF2 … … … … … … … SN 1 1 … 1 63 DIFN Table 1)

For example, in the example description of Table (1), according to the display requirements of the display panel 110, the display information DIF1 of the image signal IM records 12 light-emitting elements that need to be turned on in the display row S1, and the display information DIF2 of the image signal IM It records that 48 light-emitting elements need to be turned on in the display row S2, and the display information DIFN of the image signal IM records that 63 light-emitting elements need to be turned on in the display row SN.

On the other hand, the data converter 125 can receive a plurality of display information DIF1˜DIFN of the image signal IM. The data converter 125 can perform data conversion (for example, decoding operation or conversion into binary system) on the quantity information of the light-emitting elements indicated in each display information DIF1-DIFN to be turned on, so as to obtain the information shown in Table (2). A plurality of impedance adjustment signals IAS1˜IASN. quantity Bit[5] (A1) Bit[4] (A2) Bit[3] (A3) Bit[2] (A4) Bit[1] (A5) Bit[0] (A6) 12 0 0 1 1 0 0 IAS1 48 1 1 0 0 0 0 IAS2 … … … … … … … … 63 1 1 1 1 1 1 IASN Table 2)

For example, since the display information DIF1 indicates that the lighting demand corresponding to the display row S1 of the display panel 110 may be "the number of light-emitting elements to be lit is 12", the data converter 125 will The quantity information is decoded (or converted into binary) to obtain the impedance adjustment signal IAS1. Wherein, the impedance adjustment signal IAS1 has a bit value of "001100".

Similarly, since the display information DIF2 indicates that the lighting demand corresponding to the display row S2 of the display panel 110 may be "the number of light-emitting elements to be lit is 48", therefore, the data converter 125 will change the number of display information DIF2 The information is decoded (or converted into binary) to obtain the impedance adjustment signal IAS2. Wherein, the impedance adjustment signal IAS2 has a bit value of "110000". The rest of the impedance adjustment signals can be deduced in the same way, and will not be repeated here.

Next, the multiplexer 126 can receive the switch signal RS and a plurality of impedance adjustment signals IAS1˜IASN. The multiplexer 126 can select one of the impedance adjustment signals IAS1 -IASN according to the switching signal RS. Moreover, the image processing circuit 122 can capture the first part of bits A1-A3 (and omit the second part of bits A4-A6, ie, the least significant bit (Least Significant Bit, LSB) of the selected impedance adjustment signal. ), so that the multiplexer 126 provides the first part of bits A1 - A3 of the selected impedance adjustment signal to the switches SW21 - SW23 of the impedance adjustment circuit 130 .

Please refer to FIG. 1 to FIG. 3 at the same time. FIG. 3 is a timing diagram of the impedance adjustment circuit according to the embodiment of FIG. 2 . For example, in this embodiment, when the scan driver 120 scans the display column S1 according to the switching signal RS, the multiplexer 126 can obtain the impedance adjustment signal IAS1 according to the switching signal RS (that is, the bit value is "001100"). Next, the image processing circuit 122 can extract the first part of the bits A1-A3 of the impedance adjustment signal IAS1 (that is, the bit value is “001”), and make the multiplexer 126 match the bit value to “001”. The first part of bits A1-A3 of the impedance adjustment signal IAS1 of "is provided to the switches SW21-SW23 respectively.

In this case, the switches SW21 and SW22 can be turned off according to the first partial bits A1 and A2 of the impedance adjustment signal IAS1, respectively, and the switch SW23 can be turned off according to the first partial bit A3 of the impedance adjustment signal IAS1. conduction. At this time, the magnitude of the impedance Radj of the impedance adjustment circuit 130 may be adjusted to the first impedance value Radj1. Wherein, the first impedance value Radj1 is obtained by connecting the resistor R3 and the standard resistor RT in parallel.

According to the above example, it can be known that in the case that 12 light-emitting elements are required to be lit in the display column S1, the voltage Vdrop across the switch circuit 121 and the impedance adjustment circuit 130 can be: Vdrop=Iscan11*Rdrop=Iscan11*(Rdson+Radj1)...(3)

On the other hand, when the scan driver 120 scans the display row S2 according to the switching signal RS, the multiplexer 126 can obtain the impedance adjustment signal IAS2 (that is, the bit value is “110000”) according to the switching signal RS. Next, the image processing circuit 122 can extract the first part of bits A1-A3 (that is, the bit value is “110”) of the impedance adjustment signal IAS2, and make the multiplexer 126 match the bit value to “110”. The first part of bits A1-A3 of the impedance adjustment signal IAS2 of "is provided to the switches SW21-SW23 respectively.

In this case, the switches SW21 and SW22 can be turned on respectively according to the first partial bits A1 and A2 of the impedance adjustment signal IAS2, and the switch SW23 can be turned off according to the first partial bit A3 of the impedance adjustment signal IAS2. open. At this time, the impedance Radj of the impedance adjustment circuit 130 may be adjusted to a second impedance value Radj2 that is smaller than the first impedance value Radj1. Wherein, the second impedance value Radj2 is obtained by connecting the resistors R1 , R2 and the standard resistor RT in parallel.

According to the above example, it can be known that in the case that 48 light-emitting elements are required to be lit in the display column S2, the voltage Vdrop across the switch circuit 121 and the impedance adjustment circuit 130 can be: Vdrop=Iscan12*Rdrop=Iscan12*(Rdson+Radj2)…..(4)

The implementation details of the other display columns S3 - SN by the scan driver 120 can be deduced by referring to the relevant descriptions of the above-mentioned embodiments, so details are not repeated here.

It is worth mentioning that, in this embodiment, the resistance value of the standard resistor RT is 1 ohm. The relationship between the standard resistance RT and the resistances R1~R3 is, for example, shown in formula (5): RT=R3=2*R2=4*R1…………………..(5)

According to the example description of the above formula (3) and formula (4), in this embodiment, it is assumed that the equivalent impedance of each switch in the switch circuit 121 when it is turned on is the impedance Rdson, when the scanned When the number of light-emitting elements that need to be turned on in the display row (for example, S1) is small (for example, the number information is 12), the impedance adjustment circuit 130 can increase the impedance adjustment circuit 130 according to the display information IAS1 of the image signal IM. The magnitude of the impedance Radj (that is, the first impedance value Radj1 ).

In contrast, when the number of light-emitting elements to be turned on in the scanned display row (for example, S2 ) is relatively large (for example, the number information is 48), the impedance adjustment circuit 130 can adjust the light-emitting elements according to the display information IAS2 of the image signal IM. Turn down the impedance Radj of the impedance adjustment circuit 130 (ie, the second impedance Radj2 ).

That is to say, the impedance adjustment circuit 130 of this embodiment can adjust the impedance Rdrop between the switch circuit 121 and the impedance adjustment circuit 130 according to the lighting requirement of the light emitting elements of each display column. In this way, when the number of light-emitting elements (or scanning current Iscan) to be turned on in the scanned display column is increased, the change amount of the voltage across the voltage Vdrop between the switch circuit 121 and the impedance adjustment circuit 130 can be effectively is reduced, and shortens the time for each light-emitting element to be turned on to reach the target potential that can be turned on, thereby prompting the display quality of the display panel 110 .

It is worth mentioning that, different from the current slots Iout1-IoutN in the embodiment of Table (1), they generate currents of the same magnitude to the corresponding light-emitting elements and the switch circuit 121 respectively. In the embodiment of Table (3), the constant current The plurality of current sinks Iout1 - IoutN of the driving circuit 140 can respectively generate currents of different magnitudes to the corresponding light-emitting elements and the switch circuit 121 according to the image signal IM (or the display requirement of the display panel 110 ). CH1 CH2 … CHN quantity display information S1 3 0 … 1 >12 DIF1 S2 0 2 … 1 >48 DIF2 … … … … … … … SN 3 2 … 1 >63 DIFN table 3)

For example, in this embodiment, the scan driver 120 can be pre-set, when the current magnitude of the current sink corresponding to each display row is 5mA, the weight of the lighting requirement of the corresponding light-emitting element in the display information can be "1". Therefore, assuming that the current generated by the current tank Iout1 is 15mA, the weight of the lighting requirement of the corresponding light-emitting element in the display information is "3"; assuming that the current generated by the current tank Iout2 is 10mA, the display information The weight of the lighting requirement of the light-emitting element corresponding to in is "2"; assuming that the current generated by the current tank IoutN is 5mA, the weight of the lighting requirement of the corresponding light-emitting element in the display information is "1". .

Therefore, the scan driver 120 can also adjust the weight value of the lighting requirements of the corresponding light-emitting elements in the display information according to the different current levels of the current sinks, so as to improve the accuracy of information processing.

FIG. 4 is a flowchart illustrating an impedance adjustment method of the display device shown in FIG. 1 according to an embodiment of the present invention. Please refer to FIG. 1 and FIG. 4 at the same time. In step S410 , the display device provides a display panel having a plurality of light emitting elements arranged in a plurality of display columns and a plurality of display rows. In step S420, the display device enables the scan driver to receive the image signal, and generate a plurality of driving signals to drive a plurality of light-emitting elements according to a plurality of display information of the image signal, wherein the display information is used to record a plurality of display columns in a plurality of The number of light elements that need to be lit. In step S430, the display device enables the impedance adjustment circuit to adjust the impedance of the impedance adjustment circuit according to a plurality of display information of the image signal.

The implementation details of each step have been described in detail in the aforementioned embodiments and implementation manners, and will not be repeated here.

To sum up, in the display device and the impedance adjustment method thereof described in various embodiments of the present invention, the impedance adjustment circuit can adjust the impedance between the switch circuit and the impedance adjustment circuit according to the lighting requirements of the light-emitting elements of each display column. In this way, when the number of light-emitting elements (or scanning current) that need to be lit in the scanned display column is increased, the variation of the cross-voltage voltage between the switch circuit and the impedance adjustment circuit can be effectively reduced, and The time for each light-emitting element to be turned on to reach the target potential that can be turned on is shortened, thereby prompting the display quality of the display panel.

100: display device

110: display panel

120: scan driver

121: switch circuit

122: Image processing circuit

123: Controller

124: memory

125:Data Converter

126: multiplexer

130: Impedance adjustment circuit

140: Constant current drive circuit

A1～A3: The first part of bits

CH1～CHN: display line

D11～DNM: Light emitting element

DS1～DSN: drive signal

DIF1～DIFN: display information

IAS1～IASN: Impedance adjustment signal

IM: image signal

Iout1～IoutN: current sink

Iscan, Iscan11, Iscan12, Iscan1N: scan current

Rdson, Radj, Rdrop: Impedance

RS: switching signal

RT: standard resistance

R1～R3: resistance

Radj1, Radj2: impedance value

SW11～SW1N, SW21～SW23: switch

S1～SN: display column

SS: scan signal

S410～S430: Steps

VCC: power supply voltage

Vdrop: voltage across the voltage

VSS: reference ground terminal

FIG. 1 is a schematic diagram of a display device according to an embodiment of the invention. FIG. 2 is a schematic diagram of a scan driver and an impedance adjustment circuit according to the embodiment of FIG. 1 . FIG. 3 is a timing diagram of the impedance adjustment circuit according to the embodiment of FIG. 2 . FIG. 4 is a flowchart illustrating an impedance adjustment method of the display device shown in FIG. 1 according to an embodiment of the present invention.

100: display device

110: display panel

120: scan driver

121: switch circuit

122: Image processing circuit

130: Impedance adjustment circuit

140: Constant current drive circuit

A1~A3: The first part of bits

CH1~CHN: display line

D11~DNM: Light emitting element

DS1~DSN: drive signal

IM: image signal

Iout1~IoutN: current sink

Iscan: scan current

Rdson, Radj, Rdrop: Impedance

S1~SN: display column

SS: scan signal

VCC: power supply voltage

Vdrop: voltage across the voltage

VSS: reference ground terminal

Claims (8)

A display device, comprising: a display panel with a plurality of light-emitting elements arranged into a plurality of display columns and a plurality of display rows; a scan driver coupled to the display panel for receiving an image signal, and generate a plurality of driving signals to drive the light-emitting elements according to the display information of the image signal, wherein the display information is used to record the number of the light-emitting elements in the display rows that need to be lit; an impedance adjustment a circuit, coupled to the scan driver, for adjusting the impedance of the impedance adjustment circuit according to the display information of the image signal; and a constant current drive circuit, wherein the constant current drive circuit includes: a plurality of current slots, respectively coupled to the light-emitting elements in each display row, and the current sinks respectively generate a plurality of currents to the light-emitting elements in the display rows according to the image signal, wherein the scan driver relies on the currents The current value and multiple weights are used to adjust the display information of the image signal. The display device as claimed in item 1, wherein the scan driver includes: a switch circuit having a plurality of first switches, the first switches are respectively coupled to the light emitting elements in the display columns; and an image A processing circuit, coupled to the switch circuit and the impedance adjustment circuit, wherein the image processing circuit is used for: receiving a scanning signal and the image signal, and generating a switching signal according to the scanning signal and generating these driving signals according to the image signal, so that each of the first switches lights up each of the display columns according to each of the driving signals converting the display information of the image signal to obtain a plurality of impedance adjustment signals; and selecting one of the impedance adjustment signals according to the switching signal, and retrieving the selected impedance adjustment signal A first partial bit of the signal enables the impedance adjustment circuit to adjust the impedance of the impedance adjustment circuit according to the selected first partial bit of the impedance adjustment signal. The display device as described in claim 2, wherein the image processing circuit includes: a controller, coupled to the switch circuit, for generating the switching signal and the driving signals according to the scanning signal; a memory for to store the display information of the image signal; a data converter, coupled to the memory, and used to convert the display information of the image signal to obtain the impedance adjustment signals; and a multiplexer, coupled connected to the controller, the data converter and the impedance adjustment circuit, for selecting one of the impedance adjustment signals according to the switching signal, and providing the first part of the selected impedance adjustment signal element to the impedance adjustment circuit. The display device as described in claim 3, wherein the impedance adjustment circuit includes: a standard resistor coupled to the switch circuit and a reference ground; a plurality of resistors coupled to the switch circuit; and a plurality of second switches , coupled to the resistors, the multiplexer and the reference ground, and the second switches are turned on according to the selected first part of the impedance adjustment signal. A method for adjusting impedance of a display device, comprising: providing a display panel having a plurality of light-emitting elements arranged in a plurality of display columns and a plurality of display rows; making a scan driver receive an image signal, and according to a plurality of display signals of the image signal The display information generates a plurality of driving signals to drive the light-emitting elements, wherein the display information is used to record the number of the light-emitting elements in the display rows that need to be lit; make an impedance adjustment circuit according to the image signal some display information to adjust the impedance of the impedance adjustment circuit; make a plurality of current slots of a constant current driving circuit generate a plurality of currents to the light-emitting elements in the display rows respectively according to the image signal; and make the scanning The driver adjusts the display information of the image signal according to the current values of the currents and a plurality of weights. The impedance adjustment method as claimed in item 5, further comprising: providing a switch circuit having a plurality of first switches; Make an image processing circuit receive a scanning signal and the image signal, and generate a switching signal according to the scanning signal and generate the driving signals according to the image signal, so that each of the first switches is lit according to each of the driving signals the light-emitting elements in each display row; make the image processing circuit convert the display information of the image signal to obtain a plurality of impedance adjustment signals; and make the image processing circuit select the impedances according to the switching signal adjusting one of the signals, and extracting a first partial bit of the selected impedance adjustment signal, so that the impedance adjustment circuit adjusts the impedance according to the selected first partial bit of the impedance adjustment signal Adjust the impedance of the circuit. The impedance adjustment method as described in claim 6 further includes: making a controller generate the switching signal and the driving signals according to the scanning signal; making a memory store the display information of the image signal; making a data The converter converts the display information of the image signal to obtain the impedance adjustment signals; and makes a multiplexer select one of the impedance adjustment signals according to the switching signal, and provides the selected impedance The first part of bits of the adjustment signal is sent to the impedance adjustment circuit. The impedance adjustment method as described in claim 7, further comprising: providing a standard resistance; providing multiple resistances; and The plurality of second switches are turned on according to the selected first part of the impedance adjustment signal.

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