Display driving circuit, chip and electronic equipment

Abstract

The embodiment of the utility model provides a display driving circuit, a chip and electronic equipment, the display driving circuit comprises a pull-up module, the input end of the pull-up module is connected with a power supply end, and the output end of the pull-up module is connected with a plurality of driving ports to control at least one driving port to be used as a power supply output port and output a first level signal; and the input end of the pull-down module is connected with the grounding end, and the output end of the pull-down module is connected with the plurality of driving ports so as to control at most one driving port to be used as a power grounding port and output a second level signal. According to the application, the internal resistance of the pull-up module and / or the pull-down module can be controlled according to the number of the first driving ports, so that the current output by each first driving port does not change along with the number of the first driving ports, and finally, the purpose that the brightness of each column of LEDs is consistent can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of integrated circuits, and in particular to a display driving circuit, a chip and an electronic device. Background Art

[0002] At present, small LED arrays are often used to display simple digital or symbolic information. For example, the LEDs in the traffic light array display the remaining time corresponding to the green light passing and the remaining time corresponding to the red light stopping. In the related art, small LED arrays usually display images by refreshing the columns one by one, that is, controlling multiple columns of LEDs to be lit in sequence. When all columns of LEDs are lit, the corresponding display image is formed. However, when controlling the small LED array for display, since the number of LEDs lit in each column is different, the current size of each column of LEDs is inconsistent, which causes the brightness of LEDs in different columns to be inconsistent and affects the display effect. Summary of the invention

[0003] In view of the above problems, the embodiments of the present application provide a display driving circuit, a chip and an electronic device to solve the above technical problems.

[0004] In a first aspect, an embodiment of the present application provides a display driving circuit, the display driving circuit having multiple driving ports, the display driving circuit comprising: a pull-up module, the input end of the pull-up module is connected to the power end, the output end of the pull-up module is connected to the multiple driving ports to control at least one driving port to be used as a power output port and output a first level signal; a pull-down module, the input end of the pull-down module is connected to the ground end, the output end of the pull-down module is connected to the multiple driving ports to control at most one driving port to be used as a power ground port and output a second level signal; wherein the first driving ports share the same DC voltage, and the first driving port is the driving port used as the power output port; during the operation of the display driving circuit, the internal resistance of the pull-up module and / or the pull-down module changes with the number of the first driving ports, so that the current output by each first driving port does not change with the number of the first driving ports.

[0005] In a second aspect, an embodiment of the present application further provides a chip, comprising the above-mentioned display driving circuit.

[0006] In a third aspect, an embodiment of the present application further provides an electronic device, comprising the above-mentioned chip or display driving circuit.

[0007] The present application controls at least one driving port to be used as a power output port and output a first level signal through a pull-up module, and controls at most one driving port to be used as a power ground port and output a second level signal through a pull-down module. For a column of LEDs, the first driving port can be connected to the positive pole of the LEDs lit in the column, and the driving port used as the power ground port can be connected to the negative poles of all the LEDs lit in the column, thereby controlling the corresponding number of LEDs in the column to be lit. Since the first driving port shares the same DC voltage, for multiple LEDs lit in the same column of LEDs, the multiple LEDs are in a parallel relationship. As the number of parallel LEDs increases, the current flowing through the LEDs will increase, and eventually the brightness of the LEDs lit in different columns will be different. Since the present application can control the internal resistance of the pull-up module and / or the pull-down module according to the number of the first driving ports, the current output by each first driving port can be made not to change with the number of the first driving ports, and eventually the purpose of consistent brightness of each column of LEDs can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0009] Figure 1 A schematic diagram of a small LED array driving solution in the related art is shown.

[0010] Figure 2 A schematic diagram showing the correspondence of digital symbols in the related art is shown.

[0011] Figure 3 A schematic diagram of a driving port output signal in the related art is shown.

[0012] Figure 4 A circuit diagram of a display driving circuit in an embodiment of the present application is shown.

[0013] Figure 5 Another circuit schematic diagram of the display driving circuit in the embodiment of the present application is shown.

[0014] Figure 6 A circuit diagram of a pull-down module in an embodiment of the present application is shown.

[0015] Figure 7 A circuit diagram of the first transistor in an embodiment of the present application is shown.

[0016] Figure 8Another circuit schematic diagram of the display driving circuit in the embodiment of the present application is shown.

[0017] Fig. 9 Another circuit schematic diagram of the display driving circuit in the embodiment of the present application is shown.

[0018] Fig.10 A circuit diagram of a pull-up module in an embodiment of the present application is shown.

[0019] Fig.11 A circuit diagram of the second transistor in an embodiment of the present application is shown.

[0020] Fig.12 Another circuit schematic diagram of the display driving circuit in the embodiment of the present application is shown.

[0021] Wherein, 100 displays a driving circuit, driving ports PAD1 to PADN;

[0022] 10 pull-up modules, 20 pull-down modules, pull-up signal SEG, pull-down signal COM;

[0023] A first transistor M1, a first parallel transistor MX1, a first transmission switch S1, and a first adjustable resistor Rt1;

[0024] A second transistor M2, a second parallel transistor MX2, a second transmission switch S2, a second adjustable resistor Rt2, a power supply terminal VCC, and a ground terminal GND. DETAILED DESCRIPTION

[0025] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0026] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0027] In the embodiments of the present application, it should be noted that, in this article, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0028] Moreover, the terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0029] In the description of the embodiments of the present application, words such as "example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "example" or "for example" in the embodiments of the present application is not to be interpreted as being more preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0030] In addition, the "plurality" in the embodiments of the present application refers to two or more than two. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then A, B, C, A and B, A and C, B and C, or A, B and C can be included.

[0031] It should be noted that, in the embodiments of the present application, "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.

[0032] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0033] The first pole / first end of each transistor used in the embodiments of the present application is one of the source and the drain, and the second pole / second end of each transistor is the other of the source and the drain. Since the source and drain of the transistor can be symmetrical in structure, the source and drain thereof can be structurally indistinguishable, that is, the first pole / first end and the second pole / second end of the transistor in the embodiments of the present application can be structurally indistinguishable. Exemplarily, in the case where the transistor is a P-type transistor, the first pole / first end of the transistor is the source, and the second pole / second end is the drain; exemplarily, in the case where the transistor is an N-type transistor, the first pole / first end of the transistor is the drain, and the second pole / second end is the source.

[0034] At present, small LED arrays are often used to display simple digital or symbolic information. For example, the LEDs in the traffic light array can display the remaining time for a green light to pass and the remaining time for a red light to stop passing. Figure 1 , Figure 1 A schematic diagram of a small LED array driving scheme in the related art is shown. The small LED array driving scheme includes a driving chip and an array LED. The driving chip has multiple driving ports, each of which is connected to the cathode of the corresponding column LED and / or the anode of the corresponding row LED. For example, the driving port PAD1 is connected to the cathode of LED1, LED4, LED7 and LED10 in the first column of LEDs, and is connected to the anode of LED2 and LED3 in the first row of LEDs; for another example, the driving port PAD2 is connected to the anode of LED2, LED5, LED8 and LED9 in the second column of LEDs. The cathode of the D11 light emitting diode is connected to the anode of the LED6 in the second row of LEDs and the anode of the LED1 in the first row of LEDs; for another example, the driving port PAD3 is connected to the cathode of the LED3, LED6, LED9 and LED12 in the third column of LEDs, and is connected to the anode of the LED4 and LED5 in the second row of LEDs; the driving port PAD4 is connected to the anode of the LED7, LED8 and LED9 in the fourth row of LEDs, and the driving port PAD5 is connected to the anode of the LED10, LED11 and LED12 in the fifth row of LEDs.

[0035] During the display process, if it is necessary to light up a certain LED / some LEDs in the corresponding column, the corresponding drive port is controlled to output high and low level signals. For example, when it is necessary to light up LED1, the drive port PAD1 outputs a low level signal, and the drive port PAD2 outputs a high level signal, at this time, only the LED1 light emitting diode is controlled to be lit; for another example, when it is necessary to light up LED1 and LED4 light emitting diodes, the drive port PAD1 outputs a low level signal, and the drive ports PAD2 and PAD3 output high level signals, at this time, the LED1 and LED4 light emitting diodes are controlled to be lit.

[0036] As an example of a display of digital symbols, see Figure 2 , Figure 2 A schematic diagram of displaying digital symbols in the related art is shown, wherein A1, A2 and A3 correspond to LED1, LED4 and LED7 in the first column of LEDs, respectively, B1 and B2 correspond to LED2 and LED5 in the second column of LEDs, respectively, and C1 and C2 correspond to LED3 and LED6 in the third column of LEDs, respectively. When the number "4" needs to be displayed, it is necessary to light up LED4 in the first column of LEDs first, then light up LED2 in the second column of LEDs, and then light up LED3 and LED6 in the third column of LEDs.

[0037] Specifically, the output signals of the driving ports PAD1, PAD2 and PAD3 are as follows: Figure 3 As shown, in the t1 period, the driving port PAD1 is at a low level and the driving port PAD3 is at a high level, so the LED4 in the first column of LEDs can be driven to light up; in the t2 period, the driving port PAD1 is at a high level and the driving port PAD2 is at a low level, so the LED2 in the second column of LEDs can be driven to light up; in the t3 period, the driving port PAD1 is at a high level, the driving port PAD2 is at a high level, and the driving port PAD3 is at a low level, so the LED3 and LED6 in the third column of LEDs can be driven to light up, and finally the above LED array displays the number "4".

[0038] Therefore, during the display process of the LED array, a switch circuit needs to be set inside the driver chip to continuously switch each drive port to the power supply terminal VCC or the ground terminal GND to control the LEDs in the LED array to be lit. However, in order to reduce the cost of the driver chip, a non-constant current source power supply is usually used in the related art to power the small LED array. However, since the number of LEDs lit in each column is different, the current size of each column of LEDs is inconsistent. For example, in the t1 period and the t2 period, the number of LEDs lit is 1, and the current flowing through the LED is:

[0039] Is1=U0 / (R0+R1)

[0040] Among them, U0 is the power supply voltage of the non-constant current source, R0 is the internal resistance of the switch circuit, and R1 is the resistance of the LED;

[0041] During the t3 period, the two lit LEDs are connected in parallel to the power supply terminal VCC and the ground terminal GNG, so the current flowing through the LED is:

[0042] Is2=U0 / (R0+R1 / 2) / 2

[0043] It can be seen that since the number of LEDs in each column that are lit is different, the current size of the LEDs in each column is inconsistent, which leads to inconsistent brightness of LEDs in different columns and affects the display effect.

[0044] To this end, the present application provides a display driving circuit, a chip and an electronic device, which are described in detail below.

[0045] First, see Figure 4 , Figure 4 A circuit diagram of a display driving circuit 100 in an embodiment of the present application is shown, wherein the display driving circuit 100 has a plurality of driving ports PAD1 -PADN, and the display driving circuit 100 includes a pull-up module 10 and a pull-down module 20 .

[0046] Specifically, the input end of the pull-up module 10 is connected to the power supply end VCC, the output end of the pull-up module 10 is connected to a plurality of driving ports PAD1-PADN to control at least one driving port to be used as a power output port and output a first level signal, the input end of the pull-down module 20 is connected to the ground terminal GND, and the output end of the pull-down module 20 is connected to a plurality of driving ports PAD1-PADN to control at most one driving port to be used as a power ground port and output a second level signal. For example, when the pull-up module 10 controls the driving port PAD1 and the driving port PAD2 to output a first level signal, and the pull-down module 20 controls the driving port PAD3 to output a second level signal, then the LED3 and LED6 light-emitting diodes in the third column of LEDs are lit; for another example, when the pull-up module 10 controls the driving port PAD3 to output a first level signal, and the pull-down module 20 controls the driving port PAD2 to output a second level signal, then the LED5 light-emitting diode in the second column of LEDs is lit.

[0047] It should be noted that the voltage value of the first level signal in the present application is greater than the voltage value of the second level signal, that is, the first level signal can be understood as a high level signal, and the second level signal can be understood as a low level signal.

[0048] In some embodiments of the present application, the pull-up module 10 may include a plurality of switches consistent with the number of drive ports, each switch controls whether a drive port is connected to the power supply terminal VCC, thereby controlling whether the corresponding drive port is used as a power output port. In some embodiments of the present application, the pull-up module 10 may also include switches less than the number of drive ports, each switch controls whether two or more drive ports are connected to the power supply terminal VCC, thereby controlling whether the corresponding number of drive ports are used as power output ports. In some embodiments of the present application, the pull-down module 20 may include a plurality of switches consistent with the number of drive ports, each switch controls whether a drive port is connected to the ground terminal GND, thereby controlling whether the corresponding drive port is used as a power ground port.

[0049] It can be understood that the pull-up module 10 and / or the pull-down module 20 can also include multiple switch groups, each switch group includes two or more switches connected in series, and the corresponding drive port is selected to be grounded or connected to the power supply by controlling the multiple switches of each switch group.

[0050] In the embodiment of the present application, the first drive port shares the same DC voltage, and the first drive port is a drive port used as a power output port, that is, the drive port that outputs current when controlling the LED array display is the first drive port. During the operation of the display drive circuit 100, the internal resistance of the pull-up module 10 and / or the pull-down module 20 varies with the number of the first drive ports, so that the current output by each first drive port does not vary with the number of the first drive ports. For example, an adjustable resistor can be set in the pull-down module 20. When the number of the first drive ports is 1, only one LED is connected in series between the power supply terminal VCC and the ground terminal GND. At this time, the current output by the first drive port is large, so the resistance of the adjustable resistor can be increased, so that the current output by the first drive port reaches the standard setting value (for example, 0.5A); and when the number of the first drive ports is N (N is an integer greater than or equal to 2), multiple LEDs are connected in parallel between the power supply terminal VCC and the ground terminal GND. At this time, the current output by the first drive port is small, so the resistance of the adjustable resistor can be reduced, so that the current output by the first drive port reaches the standard setting value.

[0051] That is to say, the present application controls at least one driving port to be used as a power output port and output a first level signal through the pull-up module 10, and controls at most one driving port to be used as a power ground port and output a second level signal through the pull-down module 20. For a column of LEDs, the first driving port can be connected to the positive pole of the LED lit in the column of LEDs, and the driving port used as the power ground port can be connected to the negative pole of all the LEDs lit in the column of LEDs, thereby controlling the corresponding number of LEDs in the column of LEDs to be lit. Since the first driving port shares the same DC voltage, for a plurality of LEDs lit in a column, the plurality of LEDs are in a parallel relationship. As the number of parallel LEDs increases, the current flowing through the LEDs will be reduced, and ultimately the phenomenon of different brightness due to different numbers of LEDs lit in different columns is caused. Since the present application can control the internal resistance of the pull-up module 10 and / or the pull-down module 20 according to the number of the first driving ports, the current output by each first driving port does not change with the number of the first driving ports, and ultimately the purpose of consistent brightness of each column of LEDs can be achieved.

[0052] In some embodiments of the present application, for example, the pull-down module 20 may include a plurality of switches that are consistent with the number of drive ports, see Figure 5 , Figure 5 Another circuit diagram of the display driving circuit 100 in the embodiment of the present application is shown, wherein the pull-down module 20 includes a plurality of first transistors M1, and the first transistors M1 correspond to the driving ports one by one; the first end of the first transistor M1 is used to connect to the corresponding driving port, and the second end of the first transistor M1 is used to connect to the ground terminal GND. The first transistor M1 can be one or a group of parallel transistors with a switching function. When a certain first transistor M1 is turned on and other first transistors M1 are turned off, the corresponding driving port is grounded and used as a power ground port to output a second level signal.

[0053] Exemplarily, the first transistor M1 may include a transistor with a switching function, such as a MOS transistor, a triode, an IGBT transistor or a JFET transistor.

[0054] In some embodiments of the present application, for example, for an embodiment in which the internal resistance of the pull-down module 20 varies with the number of the first driving ports, see Figure 6 , Figure 6 A circuit schematic diagram of the pull-down module 20 in an embodiment of the present application is shown, wherein each first transistor M1 includes a plurality of first parallel transistors MX1, the first ends of the plurality of first parallel transistors MX1 are connected to corresponding drive ports, and the second ends of the plurality of first parallel transistors MX1 are used to be connected to the ground terminal GND; the number of the plurality of first parallel transistors MX1 that are turned on varies with the number of the first drive ports.

[0055] For example, ignoring the internal resistance of the pull-up module 10, when the number of the first driving port is 1, the current flowing through the LED is:

[0056] I1=U / (R1+Ra1)

[0057] Wherein, U is the voltage difference between the power terminal VCC and the ground terminal GND, R1 is the resistance value of the LED, and Ra1 is the resistance of the first transistor M1 when the number of the first driving port is 1 (ie, the resistance corresponding to the plurality of first parallel transistors MX1).

[0058] When the number of the first driving ports is M (M is an integer greater than or equal to 2), the current flowing through a single LED is:

[0059] Im=U / (Rl / M+Ram) / M

[0060] Wherein, Ram is the resistance of the first transistor M1 when the number of the first driving ports is M (ie, the resistance corresponding to the plurality of first parallel transistors MX1)

[0061] In addition, I1=IM, so:

[0062] R1+Ra1=(R1 / M+Ram) / M

[0063] Rl*M 2 +Ra1*M 2 =(Rl+Ram*M)

[0064] Ram=(R1*(M 2 -1)+Ra1*M 2 ) / M

[0065] It can be seen that when the number of first drive ports is changed, the number of the first parallel transistors MX1 that are turned on is controlled according to the number of first drive ports to ensure that Ram satisfies the above relationship, so that the current output by each first drive port can be maintained at the standard set value.

[0066] In some embodiments of the present application, see Figure 7 , Figure 7 A structural schematic diagram of the first transistor M1 in an embodiment of the present application is shown, wherein each first transistor M1 also includes a plurality of first transmission switches S1, and the first transmission switches S1 correspond one-to-one to the first parallel transistors MX1; the first end of the first transmission switch S1 is connected to the control end of the corresponding first parallel transistor MX1, the second end of the first transmission switch S1 is used to access the pull-down signal COM, and the control end of the first transmission switch S1 is used to access the parallel control signal.

[0067] Specifically, the first transmission switch S1 can control whether the control end of the first parallel transistor MX1 ​​is connected to the pull-down signal COM according to the parallel control signal. For example, taking the first parallel transistor MX1 ​​as an NMOS tube, when the pull-down signal COM corresponding to a certain first transistor M1 is high, the first transmission switch S1 can control whether the control end of the corresponding first parallel transistor MX1 ​​receives the first level signal, so that multiple first parallel transistors MX1 corresponding to the first transistor M1 can use the same pull-down signal COM, and use the parallel control signal to control the number of first parallel transistors MX1 that are turned on, and finally realize the decoupling of controlling the conduction of the first transistor M1 and controlling the number of first parallel transistors MX1 that are turned on.

[0068] For example, the first transmission switch S1 may be an electronic component or circuit with a switching function, such as a MOS tube, a triode, an IGBT tube, a JFET tube or a transmission gate.

[0069] In some embodiments of the present application, for example, for an embodiment in which the internal resistance of the pull-down module 20 varies with the number of the first driving ports, see Figure 8 , Figure 8 Another schematic diagram of the display driving circuit 100 in an embodiment of the present application is shown, wherein the pull-down module 20 also includes a first adjustable resistor Rt1, one end of the first adjustable resistor Rt1 is connected to the second ends of the plurality of first transistors M1, and the other end is connected to the ground terminal GND, and the resistance value of the first adjustable resistor Rt1 varies with the number of the first driving ports.

[0070] For example, ignoring the internal resistance of the pull-up module 10, when the number of the first driving port is 1, the current flowing through the LED is:

[0071] I1=U / (Rl+Rt11+Ra)

[0072] Wherein, U is the voltage difference between the power terminal VCC and the ground terminal GND, R1 is the resistance value of the LED, Ra is the resistance value of the single first transistor M1, and Rt11 is the resistance of the first adjustable resistor Rt1 when the number of the first driving port is 1.

[0073] When the number of the first driving ports is M (M is an integer greater than or equal to 2), the current flowing through a single LED is:

[0074] Im=U / (Rl / M+Rt1m+Ra) / M

[0075] Wherein, Rt1m is the resistance of the first adjustable resistor Rt1 when the number of the first driving ports is M.

[0076] Let I1=Im, we can know:

[0077] Rl+Rt11+Ra=(Rl / M+Rt1m+Ra) / M

[0078] M 2 *(Rl+Rt11+Ra)=(Rl+Rt1m*M+Ra*M)

[0079] When the number of the first driving ports is M, the resistance value of the first adjustable resistor Rt1 satisfies the following relationship:

[0080] Rt1m=(M 2 *Rt11+(M 2 -M)*Ra+(M 2 -1)*R1) / M

[0081] It can be seen that when the number of the first driving ports changes, it is only necessary to adjust the resistance value of the first adjustable resistor Rt1 and satisfy the above relationship, so that the current output by each first driving port is kept at the standard set value.

[0082] In some embodiments of the present application, for example, the pull-up module 10 may include a plurality of switches having the same number as the number of the drive ports. Fig. 9 , Fig. 9 Another circuit diagram of the display driving circuit 100 in the embodiment of the present application is shown, wherein the pull-up module 10 includes a plurality of second transistors M2, and the second transistors M2 correspond to the driving ports one by one; the first end of the second transistor M2 is used to connect to the corresponding driving port, and the second end of the second transistor M2 is used to connect to the power supply terminal VCC. The second transistor M2 can be one or a group of parallel transistors with a switching function. When one or some of the second transistors M2 are turned on, the corresponding driving port is connected to the power supply terminal VCC and used as a power output port to output a first level signal.

[0083] Exemplarily, the first transistor M1 may include a transistor with a switching function, such as a MOS transistor, a triode, an IGBT transistor or a JFET transistor.

[0084] In some embodiments of the present application, for example, for an embodiment in which the internal resistance of the pull-up module 10 can be changed with the number of the first driving ports, see Fig.10 , Fig.10 A circuit schematic diagram of the pull-up module 10 in an embodiment of the present application is shown, wherein each second transistor M2 includes a plurality of second parallel transistors MX2; the first ends of the plurality of second parallel transistors MX2 are connected to the corresponding drive ports, and the second ends of the plurality of second parallel transistors MX2 are used to be connected to the power supply terminal VCC; the number of the plurality of second parallel transistors MX2 that are turned on varies with the number of the first drive ports.

[0085] For example, when the number of the first driving port is 1, that is, only one LED in a column of LEDs is lit, the current flowing through the LED is:

[0086] I1=U / (Rl+Rb1+Ra)

[0087] Among them, U is the voltage difference between the power terminal VCC and the ground terminal GND, Rl is the resistance value of the LED, Ra is the resistance value of the first transistor M1, and Rb1 is the resistance of the second transistor M2 when the number of the first driving port is 1 (that is, the resistance corresponding to multiple second parallel transistors MX2).

[0088] When the number of the first driving ports is M (M is an integer greater than or equal to 2), that is, M LEDs in a column of LEDs are lit, the current flowing through a single LED is:

[0089] Im=U / ((Rl+Rbm) / M+Ra) / M

[0090] Wherein, Rbm is the resistance of the second transistor M2 when the number of the first driving ports is M (ie, the resistance corresponding to the plurality of second parallel transistors MX2 ).

[0091] Let I1 = Im, we can know:

[0092] Rl+Rb1+Ra=((Rl+Rbm) / M+Ra) / M

[0093] M 2 *(Rl+Rb1+Ra)=(Rl+Rbm+M*Ra)

[0094] Rbm=M 2 *Rb1+Ra*(M 2 -M)+Rl*(M 2 -1)

[0095] It can be seen that when the number of first drive ports is changed, the number of the second parallel transistors MX2 that are turned on is controlled according to the number of first drive ports to ensure that Rbm satisfies the above relationship, so that the current output by each first drive port can be maintained at the standard set value.

[0096] In some embodiments of the present application, see Fig.11 , Fig.11A structural schematic diagram of the first transistor M1 in an embodiment of the present application is shown, wherein each second transistor M2 also includes a plurality of second transmission switches S2, and the second transmission switches S2 correspond one-to-one to the second parallel transistors MX2; the first end of the second transmission switch S2 is connected to the control end of the corresponding second parallel transistor MX2, the second end of the second transmission switch S2 is used to access the pull-up signal SEG, and the control end of the second transmission switch S2 is used to access the parallel control signal.

[0097] Specifically, the second transmission switch S2 can control whether the control end of the second parallel transistor MX2 is connected to the pull-up signal SEG according to the parallel control signal. For example, taking the second parallel transistor MX2 as a PMOS tube as an example, when the pull-up signal SEG corresponding to a second transistor M2 is low, the second transmission switch S2 can control whether the control end of the corresponding second parallel transistor MX2 receives the second level signal, so that multiple second parallel transistors MX2 corresponding to the second transistor M2 can use the same pull-up signal SEG, and use the parallel control signal to control the number of second parallel transistors MX2 that are turned on, and finally realize the decoupling of controlling the conduction of the second transistor M2 and controlling the number of second parallel transistors MX2 that are turned on.

[0098] For example, the second transmission switch S2 may be an electronic component or circuit with a switching function, such as a MOS tube, a triode, an IGBT tube, a JFET tube or a transmission gate.

[0099] In some embodiments of the present application, for example, for an embodiment in which the internal resistance of the pull-up module 10 varies with the number of the first driving ports, see Fig.12 , Fig.12 Another schematic diagram of the display driving circuit 100 in an embodiment of the present application is shown, wherein the pull-up module 10 also includes a second adjustable resistor Rt2, one end of the first adjustable resistor Rt2 is connected to the second ends of the plurality of second transistors M2, and the other end is connected to the power supply end VCC, and the resistance value of the second adjustable resistor Rt2 varies with the number of the first driving ports.

[0100] For example, ignoring the internal resistance of the pull-up module 10, when the number of the first driving ports is 1, the number of the first parallel transistors MX1 that are turned on is 1, and the current flowing through the LED is:

[0101] I1=U / (Rl+Rt21+Ra+Rb)

[0102] Among them, U is the voltage difference between the power terminal VCC and the ground terminal GND, Rl is the resistance value of the LED, Ra is the resistance value of the single first transistor M1, Rb is the resistance value of the single second transistor M2, and Rt21 is the resistance of the second adjustable resistor Rt2 when the number of the first driving port is 1.

[0103] When the number of the first driving ports is M (M is an integer greater than or equal to 2), the current flowing through a single LED is:

[0104] Im=U / ((Rl+Rb) / M+Rt2m+Ra) / M

[0105] Wherein, Rt2m is the resistance of the second adjustable resistor Rt2 when the number of the first driving ports is M.

[0106] Let I1 = Im, then (Rl + Rt21 + Ra + Rb) = ((Rl + Rb) / M + Rt2m + Ra) / M, then when the number of the first drive ports is M, the resistance value of the second adjustable resistor Rt2 satisfies the following relationship:

[0107] Rt2m=(M 2 *Rt21+(M 2 -1)*R1+(M 2 -M)*Ra+(M 2 -1)*Rb) / M

[0108] It can be seen that when the number of the first driving ports changes, it is only necessary to adjust the resistance value of the second adjustable resistor Rt2 and satisfy the above relationship, so that the current output by each first driving port is kept at the standard set value.

[0109] It is worth noting that the above-mentioned display driving circuit 100 is intended to clearly illustrate the implementation verification process of the present application. Those skilled in the art can also make equivalent modified designs under the guidance of the present application. For example, the pull-up module 10 includes a second adjustable resistor Rt2 and the pull-down module 20 includes a first adjustable resistor Rt1. By simultaneously adjusting the second adjustable resistor Rt2 and the first adjustable resistor Rt1, the current output by each first driving port is maintained at a standard set value.

[0110] The embodiment of the present application also provides a chip, which includes the above-mentioned display driving circuit 100. A chip (Integrated Circuit, IC) is also called a chip, and the chip can be, but is not limited to, a SOC (System on Chip) chip or a SIP (system in package) chip. The chip controls the pull-up module 10 and / or the pull-down module 20 according to the number of the first driving ports, so that the current output by each first driving port does not change with the number of the first driving ports, and finally achieves the purpose of uniform brightness of each column of LEDs.

[0111] The embodiment of the present application also provides an electronic device, which includes a device body and a chip as described above provided in the device body. The electronic device may be, but is not limited to, a weight scale, a body fat scale, a nutrition scale, an infrared electronic thermometer, a pulse oximeter, a human body composition analyzer, a mobile power supply, a wireless charger, a fast charger, a car charger, an adapter, a display, a USB (Universal Serial Bus) docking station, a stylus, a true wireless headset, a car central control screen, a car, a smart wearable device, a mobile terminal, and a smart home device. Smart wearable devices include, but are not limited to, smart watches, smart bracelets, and cervical massagers. Mobile terminals include, but are not limited to, smart phones, laptops, tablet computers, and POS (point of sales terminal). Smart home devices include, but are not limited to, smart sockets, smart rice cookers, smart sweepers, and smart lights.

[0112] The above are only preferred embodiments of the present application, and are not intended to limit the present application in any form. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technical personnel in the field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present application. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A display driving circuit, characterized in that: The display driving circuit has a plurality of driving ports, and the display driving circuit comprises: A pull-up module, wherein an input end of the pull-up module is connected to a power supply end, and an output end of the pull-up module is connected to the plurality of drive ports to control at least one of the drive ports to be used as a power output port and output a first level signal; A pull-down module, wherein an input end of the pull-down module is connected to a ground end, and an output end of the pull-down module is connected to the plurality of drive ports to control at most one of the drive ports to be used as a power ground port and output a second level signal; Among them, the first drive ports share the same DC voltage, and the first drive port is the drive port used as the power output port; during the operation of the display drive circuit, the internal resistance of the pull-up module and / or the pull-down module changes with the number of the first drive ports, so that the current output by each of the first drive ports does not change with the number of the first drive ports.

2. The display driving circuit according to claim 1, characterized in that: The pull-down module includes a plurality of first transistors, and the first transistors correspond to the driving ports one by one; The first end of the first transistor is connected to the corresponding driving port, and the second end of the first transistor is connected to the ground end.

3. The display driving circuit according to claim 2, characterized in that: Each of the first transistors includes a plurality of first parallel transistors; The first ends of the plurality of first parallel transistors are connected to the corresponding driving ports, and the second ends of the plurality of first parallel transistors are connected to the ground end; The number of the first parallel transistors that are turned on varies with the number of the first driving ports.

4. The display driving circuit according to claim 3, characterized in that: Each of the first transistors further includes a plurality of first transmission switches, and the first transmission switches correspond one-to-one to the first parallel transistors; The first end of the first transmission switch is connected to the control end of the corresponding first parallel transistor, the second end of the first transmission switch is connected to a pull-down signal, and the control end of the first transmission switch is connected to a parallel control signal.

5. The display driving circuit according to claim 2, characterized in that: The pull-down module also includes a first adjustable resistor; One end of the first adjustable resistor is connected to the second ends of the plurality of first transistors, and the other end is connected to the ground end; The resistance value of the first adjustable resistor varies with the number of the first driving ports.

6. The display driving circuit according to claim 1, wherein: The pull-up module includes a plurality of second transistors, and the second transistors correspond to the driving ports one by one; The first end of the second transistor is connected to the corresponding driving port, and the second end of the second transistor is connected to the power supply end.

7. The display driving circuit according to claim 6, wherein: Each of the second transistors includes a plurality of second parallel transistors; The first ends of the plurality of second parallel transistors are connected to the corresponding driving ports, and the second ends of the plurality of second parallel transistors are connected to the power supply end; The number of the plurality of second parallel transistors that are turned on varies with the number of the first driving ports.

8. The display driving circuit according to claim 6, wherein: The pull-up module also includes a second adjustable resistor; One end of the second adjustable resistor is connected to the second ends of the plurality of second transistors, and the other end is connected to the power supply end; The resistance value of the second adjustable resistor varies with the number of the first driving ports.

9. A chip, characterized in that: The display driving circuit comprises the display driving circuit as claimed in any one of claims 1 to 8.

10. An electronic device, characterized in that: Comprising the chip as claimed in claim 9.

Images