TWI677862B - Reference voltage generating circuit, reference voltage generating method and liquid crystal display device - Google Patents

Abstract

A reference voltage generating circuit, a reference voltage generating method, and a liquid crystal display device. The reference voltage generating circuit receives a fixed frame frequency reference voltage value and a fixed frame frequency count value from the timing controller. After detecting a start pulse width of a current frame, a reference voltage value is generated according to the start pulse width, and the reference voltage value is converted into an analog reference voltage, and then a power amplification operation is performed on the analog reference voltage to With minimum delay, an adaptive reference voltage corresponding to one of the current frames is obtained.

Description

Reference voltage generating circuit, reference voltage generating method and liquid crystal display device

The invention relates to a reference voltage generating circuit, a reference voltage generating method, and a liquid crystal display device, and more particularly to a reference voltage generating scheme capable of automatically adjusting a reference voltage value in a liquid crystal display device in real time.

With the development of display technology, Thin Film Transistor-Liquid Crystal Display (TFT-LCD) has the advantages of low cost, good image quality, and low power consumption, so it is widely used in computers, televisions, and mobile phones. In other audiovisual equipment, TFT-LCD occupies a dominant position in the display field.

As shown in FIG. 1, the conventional TFT-LCD includes a timing controller 10, a source driver 11, a gate driver 12, a common voltage generating circuit 13, and an active-array liquid crystal panel 14. The active array liquid crystal panel 14 includes a plurality of pixels, each pixel is composed of three sub-pixel units of red, green, and blue, and each sub-pixel unit corresponds to a pixel capacitor and a transistor, and the pixel The element capacitor is connected between the source driver 11 and a common electrode under the control of the transistor.

TFT-LCD requires a reference voltage as a reference for all output voltages during normal operation. However, the reference voltage in the prior art is often fixed, that is, the reference voltage is generated according to a fixed frame frequency (for example, 60 Hz), so the reference voltage cannot be changed immediately with the change of the frame frequency. . In this case, the reference voltage will affect the charging of the pixel capacitor by the transistors in the display panel array. For example, when the current frame frequency is greater than the fixed frame frequency, the transistor will undercharge the pixel capacitor, and when the current frame frequency is less than the fixed frame frequency, the transistor will overcharge the pixel capacitor. In addition, the mismatch of the frame frequency and the reference voltage can also cause problems such as image sticking, which seriously affects the visual effect.

In order to solve the foregoing problem, there are known technical solutions for estimating the frame frequency by detecting the time of the entire frame to solve the foregoing problem. However, the conventional technical solution has a frame time delay when generating a dynamic reference voltage, as shown in FIG. 2, where the reference voltages V1-V8 are one frame behind the frames F1-F8. In other words, since the reference voltage provided by the conventional technical solution to the current frame is generated based on the information of the previous frame, there is a problem that the reference voltage cannot be adjusted synchronously with the frequency of the current frame. And the adjustment range of its reference voltage will also be limited by the output performance of the chip.

In order to solve the above problems, an automatic reference voltage adjustment mechanism is urgently needed in the art, so that the reference voltage can be adjusted in real time according to the information of the current frame to avoid the aforementioned various problems.

The purpose of the present invention is to use an adaptive reference voltage generating circuit to automatically adjust the voltage value of a reference voltage according to the pulse width of the start pulse signal of the current frame in a display operation of a liquid crystal display device, so that the voltage of the reference voltage The value can be matched with the scanning frequency of the current frame, and the reference voltage can be changed to the maximum, thereby avoiding problems such as image sticking and achieving the best display effect.

To achieve the above object, a reference voltage generating circuit for a liquid crystal display device is proposed. The liquid crystal display device includes a timing controller. The reference voltage generating circuit includes:

An interface module for receiving a fixed frame frequency reference voltage value and a fixed frame frequency count value from the timing controller;

A frequency detection and reference voltage calculation module is electrically connected to the interface module and the timing controller to detect a high-potential pulse period of a start pulse signal provided by the timing controller and generate a count value, and Performing a ratio operation on the fixed frame frequency reference voltage value, the fixed frame frequency count value, and the high-potential pulse period to generate a current reference voltage value;

A digital analog converter, electrically connected to the frequency detection and reference voltage calculation module, for converting the current reference voltage value into an analog reference voltage; and

An operational amplifier is electrically connected to the digital analog converter for performing a power amplification operation on the analog reference voltage to obtain an adaptive reference voltage corresponding to a current frame frequency.

In one embodiment, the ratio calculation includes a formula V _NEW = (CT * V _α ) / C _β , where V _NEW is the current reference voltage value, CT is the count value, and V _{α is} the fixed frame. The frequency reference voltage value and C _{β are} the frequency count values of the fixed frame.

To achieve the above purpose, a reference voltage generating method is proposed, which is implemented by using a reference voltage generating circuit. The reference voltage generating method includes the following steps:

Receiving a fixed frame frequency reference voltage value and a fixed frame frequency count value;

Detecting a high-potential pulse width of a start pulse signal corresponding to a current frame frequency, and performing a reference voltage parameter calculation based on the high-potential pulse width, the fixed frame frequency reference voltage value, and the fixed frame frequency count value to Generate a current reference voltage value;

Converting the current reference voltage value into an analog reference voltage; and

A power amplification operation is performed on the analog reference voltage to obtain an adaptive reference voltage corresponding to the current frame frequency.

In an embodiment, the reference voltage generating method further includes:

Using a counter to count the high-potential pulse period and generate a count value; and

Generate the current reference voltage value according to the formula V _NEW = (CT * V _α ) / C _β , where V _NEW is the current reference voltage value, CT is the count value, and V _{α is} the fixed frame frequency reference voltage Value, and C _{β is} the fixed frame frequency count value.

To achieve the above object, the present invention further provides a liquid crystal display device, which includes

A timing controller; and

A reference voltage generating circuit is electrically connected to the timing controller to perform the following operations:

Receiving a fixed frame frequency reference voltage value and a fixed frame frequency count value;

Detecting a high-potential pulse width of a start pulse signal corresponding to a current frame frequency and generating a count value, and performing according to the high-potential pulse width, the fixed frame frequency reference voltage value, and the fixed frame frequency count value A ratio operation to generate a current reference voltage value;

Converting the current reference voltage value into an analog reference voltage; and

A power amplification operation is performed on the analog reference voltage to obtain an adaptive reference voltage corresponding to the current frame frequency.

In one embodiment, the ratio calculation includes a formula V _NEW = (CT * V _α ) / C _β , where V _NEW is the current reference voltage value, CT is the count value, and V _{α is} the fixed frame. The frequency reference voltage value and C _{β are} the frequency count values of the fixed frame.

In order to enable your reviewers to further understand the structure, characteristics, and purpose of the present invention, drawings and detailed descriptions of the preferred embodiments are attached below.

Please refer to FIGS. 3-5 for the first embodiment of the present invention. FIG. 3 is a schematic diagram showing a reference voltage generating circuit for a liquid crystal display device according to the present invention. As shown in the figure, the reference voltage generating circuit 100 includes an interface module 101, a frequency detection and reference voltage calculation module 103, a digital analog converter 105, and an operational amplifier 107.

The interface module 101 is used for receiving data provided by the timing controller 200 and includes a fixed frame frequency reference voltage value V _α and a fixed frame frequency count value C _β . The frequency detection and reference voltage calculation module 103 is electrically connected to the interface module 101 and the timing controller 200 to count a high potential pulse width of a start pulse signal STV corresponding to a current frame frequency, and according to the high potential The pulse width, the fixed frame frequency reference voltage value V _α and the fixed frame frequency count value C _β perform a reference voltage parameter calculation to generate a current reference voltage value V _NEW .

In detail, as shown in FIG. 5, during operation, the timing controller 200 will provide a high-potential pulse of a start pulse signal STV during the initial period of each frame (F1, F2, F3, ...). The reference voltage calculation module 103 uses a counter to count the duration of the high-potential pulse according to the reference clock CLK to generate a count value CT, and then generates a corresponding voltage value (V1, V2) of the current reference voltage value V _NEW according to the count value CT. , V3 ...). Specifically, when the high potential pulse changes from a low potential to a high potential, the counter starts counting from zero, and when the high potential pulse becomes a low potential, the counting ends and a count value CT is generated; and the current reference voltage value V _NEW is generated according to the following formula:

V _NEW = (CT * V _α ) / C _β .

In addition, the digital analog converter 105 is electrically connected to the frequency detection and reference voltage calculation module 103 to convert the current reference voltage value V _NEW into an analog reference voltage V _REF ; and the operational amplifier 107 is electrically connected to the digital analog converter 105 to compare The analog reference voltage V _REF performs a power amplification operation to obtain an adaptive reference voltage V _REFOUT corresponding to the current frame frequency, and directly applies the adaptive reference voltage V _REFOUT to the display of the current frame.

If the current frame frequency is greater than the previous frame frequency, the voltage of the adaptive reference voltage V _REFOUT generated by the technical solution of the present invention in the current frame will be greater than that of the adaptive reference voltage V _REFOUT generated by the previous frame. Voltage; and if the current frame frequency is lower than the previous frame frequency, the voltage of the adaptive reference voltage V _REFOUT generated by the technical solution of the present invention in the current frame will be lower than the adaptive reference generated in the previous frame The voltage of the voltage V _REFOUT .

In addition, the adaptive reference voltage obtained through the reference voltage generating circuit of the present invention can be matched with the current frame frequency in real time. The corresponding situation is shown in Figure 4. That is to say, the technical solution of the present invention can make the reference voltage depend on The frame frequency is adjusted in real time to ensure that the reference voltage output by each frame can meet the charging speed requirements of each pixel for a pixel capacitor (larger (smaller) charging is required when the frame frequency is high (low) Current) to avoid the occurrence of image sticking and achieve the best visual effect.

Please refer to FIGS. 6-7 for a second embodiment of the present invention, which is a flowchart illustrating a method for generating a reference voltage according to the present invention.

The reference voltage generating method of the present invention includes the following steps:

In step S602, a fixed frame frequency reference voltage value and a fixed frame frequency count value are received.

In step S604, a high-potential pulse width period of a start pulse signal corresponding to a current frame frequency is detected, and according to the high-potential pulse width period, the fixed frame frequency reference voltage value and the fixed frame frequency meter. The value is calculated by a reference voltage parameter to generate a current reference voltage value.

In step S606, the current reference voltage value is converted into an analog reference voltage.

In step S608, a power amplification operation is performed on the analog reference voltage to obtain an adaptive reference voltage corresponding to the current frame frequency.

In addition, please refer to FIG. 7, which illustrates an embodiment of step S604, which includes the following steps:

In step S702, a counter is used to count the high-potential pulse period, and a count value is generated.

In step S704, the current reference voltage value is generated according to the formula V _NEW = (CT * V _α ) / C _β , where V _NEW is the current reference voltage value, CT is the count value, and V _{α is} the fixed value. The frame frequency reference voltage value, and C _{β is} the fixed frame frequency count value.

The third embodiment of the present invention relates to a liquid crystal display device, which includes a timing controller and a reference voltage generating circuit. The reference voltage generating circuit can perform all operations of the reference voltage generating circuit 100 as described in the first embodiment, and details are not described herein again.

To sum up, regardless of the purpose, method and effect, this case is showing its technical characteristics that are quite different from the conventional ones, and its first invention is practical, and it is also in line with the patent requirements of the invention. Granting patents at an early date will benefit society and feel good.

10‧‧‧Sequence Controller

11‧‧‧Source Driver

12‧‧‧Gate driver

13‧‧‧public voltage generating circuit

14‧‧‧ Active Array LCD Panel

100‧‧‧reference voltage generating circuit

101‧‧‧ interface module

103‧‧‧Frequency detection and reference voltage calculation module

105‧‧‧ Digital Analog Converter

107‧‧‧ Operational Amplifier

200‧‧‧ timing controller

S602‧‧‧ receives a fixed frame frequency reference voltage value and a fixed frame frequency count value

S604‧‧‧ Detects a high-potential pulse width period of a start pulse signal corresponding to a current frame frequency, and according to the high-potential pulse width period, the fixed frame frequency reference voltage value and the fixed frame frequency count value Perform a reference voltage parameter calculation to generate a current reference voltage value

S606‧‧‧ converts the current reference voltage value into an analog reference voltage

S608‧‧‧ performs a power amplification operation on the analog reference voltage to obtain an adaptive reference voltage corresponding to the current frame frequency

S702‧‧‧ uses a counter to count the high-potential pulse period and generates a count value

S704‧‧‧ generates the current reference voltage value according to the formula V _NEW = (CT * V _α ) / C _β , where V _NEW is the current reference voltage value, CT is the count value, and V _{α is} the fixed signal. Frame frequency reference voltage value, and C _{β is} the fixed frame frequency count value

FIG. 1 illustrates the structure of a conventional thin film transistor liquid crystal display; FIG. 2 illustrates the case where the dynamic reference voltage generated by the conventional thin film transistor liquid crystal display lags behind the current frame by one frame time; FIG. 3 illustrates A block diagram of an embodiment of a reference voltage generating circuit of the present invention; FIG. 4 depicts a situation where a frame displayed by a thin film transistor liquid crystal display of the present invention matches a reference voltage in real time; FIG. 5 illustrates an operation sequence of the present invention FIG. 6 shows a flowchart of an embodiment of the adaptive reference voltage generating method of the present invention; and FIG. 7 shows one of the adaptive reference voltage generating methods of FIG. 6 as one of the current reference voltage value generating steps. Example flow chart.

Claims (3)

A reference voltage generating circuit for a liquid crystal display device. The liquid crystal display device includes a timing controller. The reference voltage generating circuit includes: an interface module for receiving a fixed frame frequency reference voltage from the timing controller. Value and a fixed frame frequency count value; a frequency detection and reference voltage calculation module electrically connected to the interface module and the timing controller to detect a high level of a start pulse signal provided by the timing controller During the potential pulse, a count value is generated, and the fixed frame frequency reference voltage value, the fixed frame frequency count value, and the count value are subjected to a ratio operation to generate a current reference voltage value; a digital analog converter, an electrical The frequency detection and reference voltage calculation module is connected to convert the current reference voltage value into an analog reference voltage; and an operational amplifier is electrically connected to the digital analog converter to perform an analog reference voltage Power amplification operation to obtain an adaptive reference voltage corresponding to a current frame frequency; wherein the ratio operation includes a Formula _{V NEW = (CT * V α} ) / C β, wherein, V _NEW is the current value of the reference voltage, CT for the count _value, V α _C β for fixed information frame for the fixed frequency reference voltage, and Frame frequency count value. A reference voltage generation method is implemented by using a reference voltage generation circuit. The reference voltage generation method includes the following steps: receiving a fixed frame frequency reference voltage value and a fixed frame frequency count value; detecting and a current frame frequency A count value is generated corresponding to a high-potential pulse period of one start pulse signal, and a proportional operation is performed according to the count value, the fixed frame frequency reference voltage value, and the fixed frame frequency count value to generate a current reference voltage. Convert the current reference voltage value to an analog reference voltage; and perform a power amplification operation on the analog reference voltage to obtain an adaptive reference voltage corresponding to the current frame frequency; wherein the ratio operation includes a formula V _NEW = (CT * V _α ) / C _β , where V _NEW is the current reference voltage value, CT is the count value, V _{α is} the reference voltage value of the fixed frame frequency, and C _{β is} the fixed frame frequency Count value. A liquid crystal display device includes: a timing controller; and a reference voltage generating circuit electrically connected to the timing controller for performing the following operations: receiving a fixed frame frequency reference voltage value and a fixed frame frequency count value ; Detecting a high-potential pulse period of a start pulse signal corresponding to a current frame frequency and generating a count value, and performing a count based on the count value, the fixed frame frequency reference voltage value, and the fixed frame frequency count value; Scaling operation to generate a current reference voltage value; converting the current reference voltage value into an analog reference voltage; and performing a power amplification operation on the analog reference voltage to obtain an adaptive reference voltage corresponding to the current frame frequency; The ratio operation includes a formula V _NEW = (CT * V _α ) / C _β , where V _NEW is the current reference voltage value, CT is the count value, V _{α is} the fixed frame frequency reference voltage value, and C _{β is} the count value of the fixed frame frequency.