Display drive blanking method based on programmable line feed time

Abstract

The invention relates to the technical field of LED display, in particular to a display drive blanking method based on programmable line feed time. The system comprises an array type display driving module. The array type display driving module comprises a GRID port group and an SEG port group; the GRID port group comprises a plurality of GRID ports which are arranged in parallel, the SEG port group comprises a plurality of SEG ports which are arranged in parallel, during blanking, the first blanking module continuously sends level signals to all the GRID ports in the line feed time T2 during line-by-line scanning of the GRID ports, the second blanking module continuously sends level signals to all the SEG ports in the line feed time T2 at the same time, and the second blanking module continuously sends level signals to all the SEG ports in the line feed time T2 during line-by-line scanning of the GRID ports. And the two ends of all the LEDs between the GRID port and the SEG port are in negative pressure, so that blanking is realized. By adopting the method, the proportion of blanking time can be reduced, and the blanking is reliable.

Description

Technical Field

[0001] The invention relates to the technical field of LED display, in particular to a display drive blanking method based on programmable line-changing time. Background Art

[0002] LED display drivers have been widely used in various fields such as white appliances, small appliances, smart homes, and outdoor display lights. Figure 1 This is a common schematic diagram of array display driver, where GRID1~GRIDM are progressive scan ports, only one GRID is turned on at the same time, and the others are turned off; SEG1~SEGN, when a certain GRID port is valid, the corresponding LED is controlled to light up according to the display content. In the array LED display driver circuit, the effective time of GRID is greater than or equal to the effective time of SEG, that is, the effective time of GRID includes the effective time of SEG. In the process of GRID scanning in sequence, the interval is called the line break time or dead time. When the LED is blanked, the GRID port will be pulled to a relatively high level, and the SEG port will be pulled to a relatively low level, so that negative pressure appears at both ends of the LED to achieve blanking. In the case of effective blanking, reducing the negative pressure time of the LED can effectively increase the service life of the LED.

[0003] There are two main types of blanking for existing array LED display drivers: one is to perform blanking when the port is closed, such as Figure 2 As shown in the figure, each GRID waveform is low level when it is valid and closed when it is high level. The arrow indicates the blanking time of the port. It can be seen that the blanking time accounts for a very high proportion; when the SEG port has less valid data, the blanking time accounts for a very high proportion. The second blanking method is to perform a short blanking at the moment when the GRID is closed, such as Figure 3 As shown in the figure, when GRID is turned off, there is a very narrow pulse for blanking. The advantage of this is that the blanking time is short. In actual use, the influence of PCB layout is uncontrollable, which brings a lot of parasitic blanking. In a short period of blanking, it is highly likely that the residual charge cannot be discharged, resulting in basically no effective blanking. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a display drive blanking method based on programmable line break time, which can reduce the proportion of blanking time and make blanking reliable.

[0005] In order to solve the above problems, the following technical solutions are provided:

[0006] The display driving blanking method based on programmable line feed time of the present invention includes an array display driving module. The array display driving module includes a GRID port group and a SEG port group. The GRID port group includes a plurality of GRID ports arranged in parallel, and the SEG port group includes a plurality of SEG ports arranged side by side. The feature is that during blanking, the first blanking module continuously sends a level signal to all GRID ports within the line feed time T2 when the GRID ports are scanned row by row, and the second blanking module continuously sends a level signal to all SEG ports within the line feed time T2. A negative voltage is present across both ends of all LEDs between the GRID ports and the SEG ports, thereby achieving blanking.

[0007] In the above solution, T2 < T1 / 10, where T1 is the effective time of the GRID port.

[0008] The effective time of the SEG port is less than T1.

[0009] The first blanking module includes a controllable switch K1 and a controllable switch K2. One end of the controllable switch K2 and one end of the controllable switch K1 are both connected to all the GRID ports. The other end of the controllable switch K2 is grounded, and the other end of the controllable switch K1 is connected to the power supply VDD through a level shift circuit one. When the GRID port is in the effective state, the controllable switch K2 is closed, and in other states, the controllable switch K2 is in the open state. When the GRID port changes lines, the controllable switch K1 is closed, and in other states, the controllable switch K1 is in the open state.

[0010] The second blanking module includes a controllable switch K3. One end of the controllable switch K3 is respectively connected to the output end of the current source I1 and all the SEG ports. The input end of the current source I1 is connected to the power supply VDD, and the other end of the controllable switch K3 is grounded through a level shift circuit two. When the GRID port changes lines, the controllable switch K3 is closed, and in other states, the controllable switch K3 is in the open state.

[0011] In the above solution, V1 ≥ V2, V1 - V2 < 2a, VDD - V1 < a×Vp, V2 < a×Vp, where V1 is the displacement voltage of the level shift circuit one, V2 is the displacement voltage of the level shift circuit two, a is the number of LEDs connected between the SEG port and the GRID port, and Vp is the turn-on voltage of the LED.

[0012] In the above solution, VDD - V1 < a×(Vp - 0.3), V2 < a×(Vp - 0.3).

[0013] Adopting the above solution has the following advantages:

[0014] Since the display drive blanking method based on programmable line-break time of the present invention continuously sends level signals to all GRID ports during line-break time T2, and the second blanking module continuously sends level signals to all SEG ports during line-break time T2, all LEDs between the GRID port and the SEG port are at negative pressure at both ends, thereby achieving blanking. The blanking method blanks all LEDs simultaneously during line-break time, and the total blanking time of each LED accounts for T2 / (T1+T2) of the entire display cycle. Since T2 is less than T1, the proportion of the blanking time to the entire display cycle is relatively low, and the impact on the life of the LED is relatively small. When the parasitic resistance and capacitance of the PCB board is small, the length of T2 is reduced by programming; when the parasitic resistance and capacitance of the PCB board is large, the length of T2 is increased by programming, thereby ensuring reliable blanking. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a common array display driver;

[0016] Figure 2 It is a schematic diagram of the first blanking method in the background technology;

[0017] Figure 3 is a schematic diagram of the second blanking method in the background technology;

[0018] Figure 4 is a schematic diagram of a display drive blanking method based on programmable line break time of the present invention;

[0019] Figure 5 It is a circuit diagram of a first blanking module in a display drive blanking method based on programmable line break time of the present invention;

[0020] Figure 6 It is a circuit diagram of the second blanking module in the display driving blanking method based on programmable line break time of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0022] The display driver blanking method based on programmable line break time of the present invention includes an array display driver module. The array display driver module contains a GRID port group and a SEG port group. The GRID port group contains a plurality of GRID ports arranged in parallel, and the SEG port group contains a plurality of SEG ports arranged in parallel. During blanking, the first blanking module continuously sends a level signal to all GRID ports within the line break time T2 when the GRID ports are scanned line by line, and the second blanking module continuously sends a level signal to all SEG ports within the line break time T2, and all LEDs between the GRID port and the SEG port are at negative pressure at both ends, thereby achieving blanking. T2<T1 / 10, T1 is the effective time of the GRID port, and the effective time of the SEG port is less than T1.

[0023] like Figure 5 As shown, the first blanking module includes a controllable switch K1 and a controllable switch K2, one end of the controllable switch K2 and one end of the controllable switch K1 are connected to all GRID ports, the other end of the controllable switch K2 is grounded, and the other end of the controllable switch K1 is connected to the power supply VDD through a level shift circuit 1. When the GRID port is in an effective state, the controllable switch K2 is closed, and in other states, the controllable switch K2 is in an open state. When the GRID port changes lines, the lower blanking enable is generated, and the controllable switch K1 is closed. In other states, the controllable switch K1 is in an open state.

[0024] like Figure 6 As shown, the second blanking module includes a controllable switch K3, one end of which is connected to the output end of the current source I1 and all SEG ports respectively, the input end of the current source I1 is connected to the power supply VDD, and the other end of the controllable switch K3 is grounded through the level shift circuit 2. When the GRID port changes lines, the lower blanking is enabled, and the controllable switch K3 is closed. In other states, the controllable switch K3 is in an open state.

[0025] like Figure 4 As shown in the figure, T1 is the effective time of each GRID port, and the effective time of SEG is less than or equal to T1. GRID1 to GRIDM are effective in sequence, with an interval of T2, i.e., the line break time. Figure 1 As shown in the figure, there are N SEGs and M GRIDs. The entire display period is (T1+T2)*M, and T1 is much larger than T2 (at least 10 times). When the circuit is working, T1 is a fixed parameter, and T2 is programmable. Since any GRID port and SEG port are multiplexed, such as Figure 1 As shown, any GRID port is connected to the cathodes of N LEDs, and any SEG port is connected to the anodes of M LEDs.

[0026] When the array display driving module operates, within the display period of (T1 + T2) * M for any GRID port, the effective time only lasts for T1, as Figure 4 shown. At each line feed time, each GRID port performs blanking simultaneously. Similarly, the SEG port also performs blanking during each line feed time. Therefore, the total blanking time of each LED accounts for T2 / (T1 + T2) of the entire display period. Since T2 is much smaller than T1, the proportion of the blanking time in the entire display period is relatively low, having a small impact on the lifespan of the LED.

[0027] When the negative voltage of a normal LED does not exceed 2V, the impact on the lifespan is small. Therefore, when designing the blanking structure, as Figure 5 and Figure 6 shown, two level shift circuits are introduced. The shift voltage of level shift circuit one is V1, and the shift voltage of level shift circuit two is V2. The number of LEDs connected between the SEG port and the GRID port is a, and the conduction voltage of the LED is Vp. Then it is required that V1 ≥ V2, V1 - V2 < 2a, VDD - V1 < a × Vp, V2 < a × Vp. Further, it is required that VDD - V1 < a × (Vp - 0.3), V2 < a × (Vp - 0.3).

[0028] For example, for a commonly used red LED with a conduction voltage of 1.8V, Vdd - V1 < a × 1.5; V2 < a × 1.5;

[0029] For example, for commonly used blue and green LEDs with a conduction voltage drop of 3.2V, Vdd - V1 < a × 2.9; V2 < a × 2.9.

[0030] Adopting the blanking method of this solution, when the parasitic resistance and capacitance of the PCB board are small, the length of T2 is reduced through programming; when the parasitic resistance and capacitance of the PCB board are large, the length of T2 is increased through programming. According to actual requirements, by programming the time of T2, not only can effective blanking operations be carried out, but also the blanking time accounts for a relatively low proportion in the entire display period, reducing the impact on the lifespan of the LED, thus achieving a balance between good display effects and the lifespan of the LED at a relatively low cost.

Claims

1. A display driver blanking method based on programmable line break time, comprising an array display driver module; the array display driver module comprises a GRID port group and a SEG port group; the GRID port group comprises a plurality of GRID ports arranged in parallel, and the SEG port group comprises a plurality of SEG ports arranged in parallel; characterized in that: During blanking, the first blanking module continuously sends a level signal to all GRID ports during the line-by-line time T2 when the GRID ports are scanned line by line, and the second blanking module continuously sends a level signal to all SEG ports during the line-by-line time T2. Negative voltage is present at both ends of all LEDs between the GRID port and the SEG port, thereby achieving blanking.

2. The display drive blanking method based on programmable line break time according to claim 1, characterized in that: T2<T1 / 10 T1 is the effective time of the GRID port.

3. The display drive blanking method based on programmable line break time according to claim 2, characterized in that: The effective time of the SEG port is less than T1.

4. The display drive blanking method based on programmable line break time according to claim 1, characterized in that: The first blanking module comprises a controllable switch K1 and a controllable switch K2, one end of the controllable switch K2 and one end of the controllable switch K1 are both connected to all the GRID ports, the other end of the controllable switch K2 is grounded, and the other end of the controllable switch K1 is connected to the power supply VDD through a level shift circuit 1; when the GRID port is in an effective state, the controllable switch K2 is closed, and in other states, the controllable switch K2 is in an open state; When the GRID port is changing lines, the controllable switch K1 is closed, and in other states, the controllable switch K1 is in an open state.

5. The display drive blanking method based on programmable line break time as claimed in claim 4, characterized in that: The second blanking module includes a controllable switch K3, one end of which is respectively connected to the output end of the current source I1 and all the SEG ports, the input end of the current source I1 is connected to the power supply VDD, and the other end of the controllable switch K3 is grounded through a second level shift circuit; when the GRID port is changing lines, the controllable switch K3 is closed, and in other states, the controllable switch K3 is in an open state.

6. The display drive blanking method based on programmable line break time according to claim 5, characterized in that: V1≥V2, V1-V2<2a, VDD-V1 <a×Vp,V2<a×Vp, Wherein, V1 is the displacement voltage of the level shift circuit 1, V2 is the displacement voltage of the level shift circuit 2, a is the number of LEDs connected between the SEG port and the GRID port, and Vp is the on-state voltage of the LED.

7. The display drive blanking method based on programmable line break time according to claim 6, characterized in that: VDD-V1 <a×(Vp-0.3),V2<a×(Vp-0.3)。

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