TWI591617B - A method of automatic balancing the time constant of multiple output channels of a source driver - Google Patents

Description

Method for automatically balancing the time constant between multiple output channels of a source driver

The present invention relates to a method of balancing the time constant between output channels, and more particularly to a method of automatically balancing the time constant between a plurality of output channels of a source driver.

Referring to FIG. 1, a conventional source driver 1 includes a plurality of channel amplifiers 11, a plurality of output pads (PADs) 12, and a plurality of output channels 13 electrically connected between respective channel amplifiers 11 and output pads 12. Each output channel 13 includes a metal routing 131 and a resistor 132 (which is an electrostatic protection resistor) connected in series. In each of the output channels 13, the metal traces 131 are electrically connected to the corresponding channel amplifiers 11. The resistors 132 are electrically connected between the metal traces 131 and the corresponding output pads 12. Each channel amplifier 11 outputs a driving signal generated by the corresponding output channel 13 and the output pad 12 to a liquid crystal display (LCD) panel 2 to drive the LCD panel 2 display.

As the resolution of the LCD panel 2 increases, the channel amplifier 11, the output pad 12, and the output channel 13 included in the source driver 1 also need to be increased. However, in The distance between the adjacent output pads 12 is difficult to be the same as the distance between adjacent channel amplifiers 11 under the limitation that the overall layout space of the source driver 1 is optimized and the output pads 12 need to be connected to the LCD panel 2. Therefore, each output channel 13 is electrically connected to its corresponding output pad 12 and the channel amplifier 11 has different connection lengths. Therefore, in each output channel 13, the metal traces 131 of different lengths need to be electrically connected to them. Corresponding to the resistor 132 and the channel amplifier 11. However, the plurality of metal traces 131 of different lengths will have different equivalent resistance and capacitance (RC) values (ie, the metal traces 131 do not match), such that a time constant (and drive signal) of each output channel 13 The delay time is related to each other, and the degree of charge and discharge of the plurality of driving signals to the LCD panel 2 is inconsistent, which causes the display screen of the LCD panel 2 to be abnormal.

Accordingly, it is an object of the present invention to provide a method of automatically balancing a plurality of output channel time constants of a source driver that overcomes the disadvantages of the prior art.

Therefore, the method for automatically balancing the time constants between the plurality of output channels of the source driver is performed by a processing unit, each of the output channels includes a metal trace and a resistor connected in series, and the autobalanced source driver output channel The method of time constant includes the following steps: (A) calculating an equivalent resistance value of each metal trace; (B) calculating an equivalent capacitance value of each metal trace; (C) adjusting the length of the resistor corresponding to each of the plurality of metal traces according to the equivalent resistance value of each metal trace and the equivalent capacitance value, so that each of the plurality of resistors The resistance value changes.

The effect of the present invention is that each of the output channels can have the same time constant by automatically adjusting the length of the plurality of resistors to change the respective resistance values of the plurality of resistors.

1‧‧‧Source Driver

11‧‧‧Channel Amplifier

12‧‧‧ Output pad

13‧‧‧Output channel

131‧‧‧Metal routing

132‧‧‧resistance

2‧‧‧LCD panel

31~33‧‧‧Steps

331‧‧‧ substeps

332‧‧‧Substeps

333‧‧‧substeps

334‧‧‧Substeps

335‧‧‧substeps

Other features and advantages of the present invention will be apparent from the embodiments of the present invention, wherein: FIG. 1 is a circuit block diagram illustrating a conventional source driver; and FIG. 2 is a flow chart illustrating the present invention. An embodiment of a method of automatically balancing the time constant between a plurality of output channels of a source driver is invented.

Referring to Figure 2, an embodiment of the method of automatically balancing the time constants between a plurality of output channels of a source driver of the present invention is performed by a processing unit (not shown). It should be noted that the circuit configuration and operation of the source driver are similar to those of FIG. 1 , and therefore, the details of the multiple output channels of the auto-balanced source driver of the present invention will be described below with reference to FIG. 1 . How does the constant method improve the display of the conventional LCD panel 2 Unusual problem. The method for automatically balancing the time constants between multiple output channels of a source driver includes the following steps:

Step 31: The processing unit calculates an equivalent resistance value of each of the metal traces 131.

In the present embodiment, the processing unit calculates the equivalent resistance value of each metal trace 131 according to the following equation (1): R _j = Rs (L _j / W _j ), where equation j is A positive integer, j ≧ 3, R _j represents the equivalent resistance value of the jth metal trace 131, Rs represents a sheet resistance value, L _j represents the length of the jth metal trace 131, and W _j represents the first The width of the j metal traces 131. It should be noted that the sheet resistance value Rs is provided by the fab.

Step 32: The processing unit calculates an equivalent capacitance value of each metal trace 131.

In this embodiment, the processing unit calculates each equivalent capacitance value according to a predetermined equivalent capacitance value calculation formula. The preset equivalent capacitance value calculation formula is provided by the fab.

Step 33: The processing unit adjusts the length of the resistor 132 corresponding to each of the plurality of metal traces 131 according to the equivalent resistance value of each metal trace 131 and the equivalent capacitance value. A resistance value of each of the plurality of resistors 132 is changed.

In detail, in step 33, the detailed flow of the sub-steps 331, 332, 333, 334, and 335 is further included.

Sub-step 331: The processing unit multiplies the equivalent resistance value of each metal trace 131 and the equivalent capacitance value to obtain an equivalent resistance capacitance (RC) value.

Sub-step 332: The processing unit obtains a maximum time constant according to the resistance value of the resistor 132 corresponding to the largest one of the plurality of equivalent RC values and the corresponding metal trace 131 corresponding thereto.

In the present embodiment, the processing unit calculates the maximum time constant (ie, one output channel 13 (as a reference output channel 13) having the longest metal trace 131 in the output channels 13 according to the following equation (2). Time constant): T = R' × C' + (R' + R _ESD ) × C _PAD equation (2) where T represents the maximum time constant and R' × C' represents the largest of the plurality of equivalent RC values One of R', C' represents the equivalent resistance value of the metal trace 131 corresponding to the largest one of the plurality of equivalent RC values and the equivalent capacitance value, and R _ESD represents the plurality of The resistance value of the resistor 132 corresponding to the metal trace 131 corresponding to the largest one of the equivalent RC values, and C _PAD represents an equivalent capacitance value of each output pad 12 of the source driver 1.

Sub-step 333: the processing unit is configured according to the resistor 132 corresponding to the remaining one of the plurality of equivalent RC values and the plurality of metal traces 131 corresponding thereto The resistance value results in a plurality of time constants, each of the plurality of time constants being associated with the remaining one of the plurality of equivalent RC values and the corresponding resistance value.

In the present embodiment, the processing unit calculates each of the plurality of time constants (ie, the time constant of the remaining output channels 13 in the output channels 13) according to the following equation (3): T _i =R _i ×C _i +(R _i +R _ESDi )×C _PAD Equation (3) where i is a positive integer, i ≧ 2, T _i represents the _ith time constant of the plurality of time constants, R _i ×C _i Representing the i-th remaining equivalent RC value, R _i , C _i respectively representing the equivalent resistance value of the metal trace 131 corresponding to the ith remaining equivalent RC value and the equivalent capacitance value, R _ESDi represents The resistance value of the resistor 132 corresponding to the metal trace 131 corresponding to the ith remaining equivalent RC value, and C _PAD represents the equivalent capacitance value of each output pad 12 of the source driver 1. It should be noted that the equivalent capacitance value C _{PAD of} each output pad 12 is the same size, and will not be different because the output pads 12 are electrically connected to different output channels 13 .

Sub-step 334: The processing unit determines whether each of the plurality of time constants is equal to the maximum time constant. If yes, the process ends; if not, sub-step 335 is performed.

Sub-step 335: the processing unit adjusts a length of the resistor 132 corresponding to each of the plurality of metal traces 131 corresponding to the maximum time constant of the plurality of time constants according to the maximum time constant to change the length Multiple resistors 132 The resistance value is such that each of the plurality of time constants is equal to the maximum time constant.

It should be noted that, in this embodiment, the resistance value is finely adjusted by adjusting the length of one of the resistive layers 132. The resistance value of each resistor 132 is preset to be the same before performing the method of automatically balancing the time constant between the plurality of output channels of the source driver of the present invention. In addition, since each resistor 132 is an electrostatic protection resistor, the magnitude of the resistance affects the electrostatic discharge (ESD) protection capability of each output channel 13. The larger the resistance value of each resistor 132, each The ESD protection capability of the output channel 13 is better. Therefore, in order to ensure that the resistance value of each resistor 132 cannot be less than a predetermined minimum value to reduce the ESD protection capability of each output channel 13, the one with the longest length of the metal traces 131 in the source driver 1 ( That is, the time constant of the output channel 13 corresponding to the one with the largest equivalent RC value is taken as the maximum time constant, and the resistance value of the resistor 132 of the remaining output channel 13 is adjusted based on the maximum time constant. To change the plurality of time constants such that each output channel 13 has the same time constant.

The following is an example of i=2, and the sub-step 335 is explained, but is not limited thereto. In this case, there is a reference output channel 13 and two remaining output channels 13, and the maximum time constant of the reference output channel 13 can be known according to equation (2), and two remaining outputs can be known according to equation (3). The time constant of channel 13. Since the metal trace 131 of the reference output channel 13 has the longest length, R'>R _i (ie, R'>R ₁ and R'>R ₂ ), C'>C _i (ie, C'>C ₁ And C'>C ₂ ) and having the largest equivalent RC value, and the equivalent capacitance value C _{PAD of} each output pad 12 is the same size, and the length of each metal trace 131 cannot be matched by the circuit design. Adjustment. Therefore, in order to make the time constant T _i (ie, the time constants T ₁ , T ₂ ) equal to the maximum time constant T, the processing unit adjusts the lengths of the resistors 132 of the two remaining output channels 13 to change their respective correspondences. The resistance value R _ESDi (ie, the resistance values R _ESD1 , R _{ESD2 is} increased), so that the respective time constants T _i of the two remaining output channels 13 are equal to the maximum time constant T, while not reducing each output channel. 13 ESD protection capabilities.

It should be noted that the processing unit can adjust the length of each resistor 132 of the remaining output channels 13 according to the method of automatically balancing the time constants between the plurality of output channels of the source driver to make each time constant of the remaining output channels 13. Equal to the maximum time constant T. When the length of the metal trace 131 of any of the remaining output channels 13 is the same as the length of the metal trace 131 of the reference output channel 13 (ie, the equivalent RC value of any of the remaining output channels 13 is If the equivalent RC value of the reference output channel 13 is the same, then the time constant is also equal to the maximum time constant T. Thus, the length of the resistor 132 of any one of the remaining output channels 13 does not need to be adjusted. .

In summary, according to the method of automatically balancing the time constants between the plurality of output channels of the source driver, the resistance value of the respective resistors 132 of the remaining output channels 13 is automatically adjusted, so that the time constant of the remaining output channels 13 is equal to the The maximum time constant T (ie, the time constant of each output channel 13 is the same), so that multiple drive letters The degree of charge and discharge of the LCD panel 2 is the same, and the problem of abnormal display screen of the conventional LCD panel 2 can be improved, thereby achieving the object of the present invention.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the equivalent equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still The scope of the invention is covered.

31~33‧‧‧Steps

331‧‧‧ substeps

332‧‧‧Substeps

333‧‧‧substeps

334‧‧‧Substeps

335‧‧‧substeps

Claims (5)

A method for automatically balancing time constants between multiple output channels of a source driver is performed by a processing unit, each output channel includes a metal trace connected in series and a resistor, and the time constant between output channels of the autobalanced source driver The method comprises the steps of: (A) calculating an equivalent resistance value of each metal trace; (B) calculating an equivalent capacitance value of each metal trace; and (C) calculating the metal trace according to each metal trace The equivalent resistance value and the equivalent capacitance value adjust the length of the resistor corresponding to each of the plurality of metal traces, so that a resistance value of each of the plurality of resistors changes. The method of automatically balancing a plurality of output channel time constants of a source driver according to claim 1, wherein in step (A), the processing unit calculates the equivalent resistance value of each metal trace according to the following equation : R _j = Rs(L _j /W _j ), where j is a positive integer, j ≧ 3, R _j represents the equivalent resistance value of the jth metal trace, Rs represents a piece of resistance value, and L _j represents the The length of the jth metal trace, and W _j represents the width of the jth metal trace. The method for automatically balancing a plurality of output channel time constants of a source driver according to claim 1, wherein the step (C) comprises the following substeps: (C1) the equivalent resistance value of each metal trace and the The equivalent capacitance values are multiplied to obtain an equivalent resistance capacitance value; (C2) the resistance value of the resistance corresponding to the largest one of the plurality of equivalent resistance capacitance values and the corresponding metal trace To a maximum time constant; (C3) obtaining a plurality of time constants according to the resistance value of the resistors corresponding to the remaining ones of the plurality of equivalent resistor capacitance values and the plurality of metal traces corresponding thereto, wherein the plurality of time constants Each of the plurality of equivalent resistance capacitance values corresponding to the corresponding one of the resistance values; and (C4) determining whether each of the plurality of time constants is equal to the maximum time constant; And (C5) determining, in the sub-step (C4), that the plurality of metal traces corresponding to the plurality of metal traces corresponding to the maximum time constant are different according to the maximum time constant a length of the resistor to vary the resistance value of each of the plurality of resistors such that each of the plurality of time constants is equal to the maximum time constant. The method of automatically balancing a plurality of output channel time constants of a source driver according to claim 3, wherein in the sub-step (C2), the processing unit calculates the maximum time constant according to the following equation: T=R'× C'+(R'+R _ESD )×C _PAD , where T represents the maximum time constant, and R′×C′ represents the largest one of the plurality of equivalent resistance and capacitance values, and R′ and C′ respectively represent The equivalent resistance value of the metal trace corresponding to the largest one of the plurality of equivalent resistance and capacitance values and the equivalent capacitance value, and R _ESD represents the largest one of the plurality of equivalent resistance and capacitance values Corresponding to the resistance value of the resistor corresponding to the metal trace, C _PAD represents an equivalent capacitance value of an output pad in a source driver. A method of automatically balancing a plurality of output channel time constants of a source driver as described in claim 3, wherein in sub-step (C3), the processing unit calculates each of the plurality of time constants according to the following equation :T _i =R _i ×C _i +(R _i +R _ESDi )×C _PAD , where i is a positive integer, i ≧ 2, T _i represents the _ith time constant of the plurality of time constants, R _i ×C _i represents the i-th remaining equivalent resistance capacitance value, and R _i and C _i respectively represent the equivalent resistance value of the metal trace corresponding to the i-th remaining equivalent resistance capacitance value and the equivalent capacitance value R _ESDi represents the resistance value of the resistance corresponding to the metal trace corresponding to the ith remaining equivalent resistance capacitance value, and C _PAD represents an equivalent capacitance value of an output pad in a source driver.