TWI832390B - Display device, frequency correction circuit and frequency correction method thereof - Google Patents

Abstract

A frequency correction circuit for a display device, which has: a receiving unit for receiving a display signal and obtaining an external frequency clock signal according to the display signal; a frequency oscillator for generating an internal frequency according to a control parameter frequency clock signal; a temperature detection module to obtain the current temperature of the frequency correction circuit; and a frequency chasing calculation unit to adjust the control parameter according to the current temperature to make the frequency of the internal frequency clock signal n times is the same as the frequency of the external frequency clock signal, where n is a positive real number.

Description

Display device, frequency correction circuit and frequency correction method thereof

The present invention relates to display driving technology, and in particular, to a frequency correction method of a display driving clock signal.

When an existing display device displays a picture, an application processor transmits a display signal to a frequency chasing chip, and the frequency chasing chip obtains a line synchronization signal, a frame synchronization signal and an external frequency clock signal from the display signal. And an internal frequency clock signal is generated according to the external frequency clock signal, wherein the frequency of the external frequency clock signal is a multiple of the frequency of the internal frequency clock signal.

In addition, generally speaking, the external frequency clock signal attached to the display signal is generated by a quartz oscillator, and its frequency is not easy to drift with temperature; and the internal frequency clock signal is generally generated by a voltage and current oscillation circuit, and its frequency Susceptible to drift due to temperature and process variations. Therefore, a frequency tracking mechanism inside the frequency tracking chip is required to correct the frequency of the internal frequency clock signal to ensure that the frequency of the internal frequency clock signal and the frequency of the external frequency clock signal maintain a fixed multiple relationship.

However, the existing frequency tracking mechanism does not take into account that the voltage and current oscillation circuit will produce frequency drift with temperature changes, so that the control parameters generated by the frequency tracking operation within a preset timing period cannot make the internal frequency clock The frequency of the signal and the frequency of the external frequency clock signal maintain a fixed multiple relationship. That is, after the temperature changes, the existing frequency tracking mechanism can no longer generate accurate control parameters within the preset timing period. It requires Longer time produces more statistical values to reduce offset error. In addition, when the display device performs low-resolution display, due to the low frequency of the internal frequency clock signal, the number of statistical values obtained by the existing frequency tracking mechanism during the preset timing period is also low, resulting in The frequency tracking effect is poor and the display quality is poor.

In order to solve the above problems, a novel frequency correction method for display devices is urgently needed in this field.

One object of the present invention is to disclose a frequency correction method for a display device, which can adjust a control parameter according to changes in ambient temperature so that the frequency of a display driving clock signal is the same as the frequency of an external reference clock signal.

Another object of the present invention is to disclose a frequency correction method for a display device, which can adjust a control parameter within a variable counting time so that the frequency of a display driving clock signal is the same as the frequency of an external reference clock signal. , thereby improving the display quality of small resolution display operations.

Another object of the present invention is to disclose a frequency correction circuit for a display device, which can prevent the display quality of a display device from being affected by changes in ambient temperature by executing the aforementioned method, and can enable the display device to operate for a small period of time. The resolution display provides a stable display screen during operation.

Another object of the present invention is to disclose a display device, which can use the aforementioned frequency correction circuit to make its display quality not affected by changes in ambient temperature, and to have a stable display screen when performing a small resolution display operation. .

In order to achieve the above purpose, a frequency correction circuit for a display device is proposed, which has: A receiving unit used to receive a display signal and obtain an external frequency clock signal according to the display signal; A frequency oscillator for generating an internal frequency clock signal according to a control parameter; A temperature detection module to obtain the current temperature of the frequency correction circuit; and A frequency chasing calculation unit is used to adjust the control parameter according to the current temperature so that n times the frequency of the internal frequency clock signal is the same as the frequency of the external frequency clock signal, where n is a positive real number.

In one embodiment, the temperature sensing module has: A temperature sensor to obtain the current temperature; a temperature processing unit to convert the current temperature into a digital signal; and A temperature lookup table stores a lookup table of multiple temperature ranges and multiple counting times, for mapping a corresponding counting time according to one of the temperature ranges to which the current temperature belongs.

In one embodiment, the frequency chasing calculation unit counts the number of pulses of the internal frequency clock signal within a said counting time, and adjusts the frequency based on a comparison result of n times the number of pulses and a preset number of external frequency pulses. Describe the control parameters.

In one embodiment, the frequency chasing calculation unit changes the value of the control parameter to increase or decrease the frequency of the internal frequency clock signal when n times the number of pulses is different from the preset number of external frequency pulses.

In one embodiment, the frequency chasing calculation unit counts the number of pulses of the external frequency clock signal within a said counting time, and uses the number of pulses of the external frequency clock signal as the said external frequency predetermined pulse number. .

To achieve the above object, the present invention further provides a display device having the aforementioned frequency correction circuit for the display device.

To achieve the above object, the present invention further proposes a frequency correction method for a display device, which is implemented using a control circuit including a receiving unit, a frequency oscillator, a temperature detection module and a frequency tracking calculation unit. Methods include: Driving the receiving unit to receive a display signal and generate an external frequency clock signal according to the display signal; Driving the frequency oscillator to generate an internal frequency clock signal according to a control parameter; Use the temperature detection module to obtain the current temperature of the control circuit; and The frequency chasing calculation unit is driven to adjust the control parameter according to the current temperature so that n times the frequency of the internal frequency clock signal is the same as the frequency of the external frequency clock signal, where n is a positive real number.

In one embodiment, the temperature sensing module has: A temperature sensor to obtain the current temperature; a temperature processing unit to convert the current temperature into a digital signal; and A temperature lookup table stores a lookup table of multiple temperature ranges and multiple counting times, for mapping a corresponding counting time according to one of the temperature ranges to which the current temperature belongs.

In one embodiment, the frequency chasing calculation unit counts the number of pulses of the internal frequency clock signal within a said counting time, and adjusts the frequency based on a comparison result of n times the number of pulses and a preset number of external frequency pulses. Describe the control parameters.

In one embodiment, the frequency chasing calculation unit changes the value of the control parameter to increase or decrease the frequency of the internal frequency clock signal when n times the number of pulses is different from the preset number of external frequency pulses.

In one embodiment, the frequency chasing calculation unit counts the number of pulses of the external frequency clock signal within a said counting time, and uses the number of pulses of the external frequency clock signal as the said external frequency predetermined pulse number. .

In order to enable the review committee to further understand the structure, characteristics and purpose of the present invention, drawings and detailed descriptions of preferred embodiments are attached as follows.

Please refer to FIG. 1 , which illustrates a block diagram of a display device according to an embodiment of the present invention. As shown in FIG. 1 , a display device 100 displays a picture according to a display signal S _DISP provided by an application processor 200 , and has a frequency correction circuit 110 , a temperature sensor 120 , and a display driving unit 130 And a pixel array 140, wherein the frequency correction circuit 110 includes a receiving unit 111, an oscillator 112, a temperature processing unit 113, a temperature lookup table 114, a frequency tracking calculation unit 115 and a control unit 116. The temperature sensor The detector 120 is used to sense the current temperature of the frequency correction circuit 110, and the display driving unit 130 is used to drive the pixel array 140.

The application processor 200 is provided with a quartz oscillator (not shown in the figure) inside to generate a clock signal that is less affected by temperature for the application processor 200 to generate the display signal S _DISP .

The receiving unit 111 may include a clock and data recovery circuit to extract a line synchronization signal HS, a frame synchronization signal VS, an FSB clock signal CK_W and a display data D _P from the display signal S _DISP . Since the clock and data recovery circuits are well known in the art, they will not be described in detail here.

The oscillator 112 includes a voltage and current oscillation circuit to generate an internal frequency clock (or pixel clock) signal CK_D according to a control parameter Adj for use by the frequency tracking calculation unit 113 and to control the display driving operation of the display driving unit 130, wherein the display The driving unit 130 converts the display data _DP into an analog voltage under the control of the internal frequency clock signal CK_D to drive the pixel array 140 to display images.

The temperature processing unit 113 is used to convert the current temperature sensed by the temperature sensor 120 into a digital signal, and transmit the digital signal to the control unit 116 .

The temperature lookup table 114 stores a lookup table of multiple temperature ranges and multiple counting times, used to find the corresponding temperature to which the current temperature belongs in the temperature ranges according to the value of the current temperature output by the control unit 116 range, and map the comparison table according to the corresponding temperature range to obtain a corresponding counting time. Please refer to Table 1, which reveals an example content of the comparison table, in which X is a positive real number, and K, A, and B are positive integers. Table 1 Temperature range (degrees C) Counting time (nanoseconds) FSB preset pulse number The temperature is between -20 and 10 X+600 K+B Temperature between 10 and 25 X+300 K+A Temperature between 25 and 40 X K Temperature between 40 and 70 X+300 K+A Temperature greater than 70 X+600 K+B

The frequency tracking calculation unit 115 is used to adjust the control parameter Adj according to the current temperature so that n times the frequency of the internal frequency clock signal CK_D is the same as the frequency of the external frequency clock signal CK_W, where n is a positive real number. Specifically, the frequency chasing calculation unit 115 counts the number of pulses of the internal frequency clock signal CK_D within a said counting time, and adjusts the control parameter Adj according to the comparison result between n times the number of pulses and a preset number of external frequency pulses. , wherein the frequency chasing calculation unit 115 changes the value of the control parameter Adj to increase or decrease the frequency of the internal frequency clock signal CK_D when n times the number of pulses is different from the preset number of external frequency pulses. For example, when n times the number of pulses is less than the preset number of external frequency pulses, increase the value of the control parameter Adj to increase the frequency of the internal frequency clock signal CK_D; and when n times the number of pulses is not less than the preset number of external frequency pulses When the number of pulses is high, reduce the value of the control parameter Adj to reduce the frequency of the internal frequency clock signal CK_D. In addition, the frequency chasing calculation unit 115 may count the number of pulses of the external frequency clock signal CK_W within the counting time, and use the number of pulses of the external frequency clock signal CK_W as the predetermined number of external frequency pulses. Please refer to FIG. 2 , which illustrates an operating waveform diagram of the frequency tracking calculation unit 115 . As shown in FIG. 2 , during the counting time of The external frequency count value and the second clock signal obtained by the second division value of the internal frequency clock signal CK_D are counted to obtain an internal frequency count value with a value of K', and the frequency chasing calculation unit 115 can be based on K' The difference between K' and K adjusts the value of the control parameter Adj to reduce the difference between K' and K within the next counting time.

The control unit 116 is used to control the operation of the frequency chasing calculation unit 115 and provide the counting time to the frequency chasing calculation unit 115 .

As can be seen from the above description, the present invention discloses a frequency correction method for a display device. Please refer to FIG. 3 , which illustrates a flow chart of an embodiment of a frequency correction method for a display device of the present invention. As shown in Figure 3, the method includes the following steps: driving a receiving unit to receive a display signal and generating an external frequency clock signal according to the display signal (step a); driving the frequency oscillator to generate an internal frequency clock according to a control parameter signal (step b); use the temperature detection module to obtain the current temperature of the control circuit (step c); and drive the frequency tracking calculation unit to adjust the control parameters according to the current temperature so that the internal frequency clock signal n times the frequency is the same as the frequency of the external frequency clock signal, where n is a positive real number (step d).

In the above embodiment, the temperature sensing module may have: a temperature sensor to obtain the current temperature; a temperature processing unit to convert the current temperature into a digital signal; and a The temperature lookup table stores a comparison table of multiple temperature ranges and multiple counting times, and is used to map a corresponding counting time according to one of the temperature ranges to which the current temperature belongs.

In addition, the frequency chasing calculation unit can count the number of pulses of the internal frequency clock signal within a said counting time, and adjust the control parameter according to a comparison result of n times the number of pulses and a preset number of external frequency pulses.

In addition, the frequency chasing calculation unit can change the value of the control parameter to increase or decrease the frequency of the internal frequency clock signal when n times the number of pulses is different from the preset number of external frequency pulses.

In addition, the frequency chasing calculation unit can count the number of pulses of the external frequency clock signal within a counting time, and use the number of pulses of the external frequency clock signal as the preset external frequency pulse number.

Through the design disclosed above, the present invention has the following advantages: 1. The frequency correction method for a display device of the present invention can adjust a control parameter according to changes in ambient temperature so that the frequency of a display driving clock signal is the same as the frequency of an external reference clock signal. 2. The frequency correction method for a display device of the present invention can adjust a control parameter within a variable counting time so that the frequency of a display driving clock signal is the same as the frequency of an external reference clock signal, thereby improving a small resolution. Display quality of display operation. 3. The frequency correction circuit for a display device of the present invention can perform the aforementioned method so that the display quality of a display device is not affected by changes in ambient temperature, and can enable the display device to perform a small-resolution display operation. Stable display. 4. The display device of the present invention can use the aforementioned frequency correction circuit to prevent the display quality from being affected by changes in ambient temperature, and to have a stable display screen when performing a small resolution display operation.

What is disclosed in this case is a preferred embodiment. Any partial changes or modifications derived from the technical ideas of this case and easily inferred by those familiar with the art will not deviate from the scope of the patent rights of this case.

To sum up, regardless of the purpose, means and effects of this case, it shows that it is completely different from the conventional technology, and that the invention is practical first, and indeed meets the patent requirements for inventions. I sincerely ask the review committee to take a clear look and grant the patent as soon as possible for your benefit. Society is a prayer for the Supreme Being.

100:Display device 110: Frequency correction circuit 111: Receiving unit 112:Oscillator 113:Temperature processing unit 114: Temperature query table 115: Frequency chasing calculation unit 116:Control unit 120:Temperature sensor 130: Display driver unit 140: Pixel array 200:Application processor Step a: Driving a receiving unit to receive a display signal and generate an external frequency clock signal based on the display signal Step b: Drive the frequency oscillator to generate an internal frequency clock signal according to a control parameter Step c: Use the temperature detection module to obtain the current temperature of the control circuit Step d: Drive the frequency chasing calculation unit to adjust the control parameter according to the current temperature so that n times the frequency of the internal frequency clock signal is the same as the frequency of the external frequency clock signal, where n is a positive real number.

FIG. 1 is a block diagram of a display device according to an embodiment of the present invention. FIG. 2 illustrates an operating waveform diagram of a frequency tracking calculation unit in the frequency correction circuit of the display device of FIG. 1 . FIG. 3 is a flow chart illustrating an embodiment of a frequency correction method for a display device of the present invention.

Step a: Driving a receiving unit to receive a display signal and generate an external frequency clock signal based on the display signal

Step b: Drive the frequency oscillator to generate an internal frequency clock signal according to a control parameter

Step c: Use the temperature detection module to obtain the current temperature of the control circuit

Step d: Drive the frequency chasing calculation unit to adjust the control parameter according to the current temperature so that n times the frequency of the internal frequency clock signal is the same as the frequency of the external frequency clock signal, where n is a positive real number.

Claims (9)

A frequency correction circuit for a display device, which has: a receiving unit for receiving a display signal and obtaining an external frequency clock signal according to the display signal; a frequency oscillator for generating an internal frequency according to a control parameter frequency clock signal; a temperature detection module to obtain the current temperature of the frequency correction circuit; and a frequency chasing calculation unit to adjust the control parameter according to the current temperature to make the frequency of the internal frequency clock signal n times is the same as the frequency of the external frequency clock signal, where n is a positive real number; wherein, the temperature detection module has: a temperature sensor to obtain the current temperature; a temperature processing unit to to convert the current temperature into a digital signal; and a temperature lookup table that stores a lookup table of multiple temperature ranges and multiple counting times to map a temperature range according to one of the temperature ranges to which the current temperature belongs. corresponding to the counting time. The frequency correction circuit for a display device as described in item 1 of the patent application, wherein the frequency tracking calculation unit counts the number of pulses of the internal frequency clock signal within a said counting time, and calculates the pulse number according to the number of pulses. The control parameter is adjusted based on the comparison result between n times and an external frequency preset pulse number. The frequency correction circuit for a display device as described in item 2 of the patent application, wherein the frequency tracking calculation unit changes the control parameter when n times the number of pulses is different from the preset number of external frequency pulses. value to increase or decrease the frequency of the internal frequency clock signal. The frequency correction circuit for a display device as described in item 2 of the patent application, wherein the frequency tracking calculation unit counts the number of pulses of the external frequency clock signal within a said counting time, and calculates the frequency of the external frequency clock signal. The pulse number of the signal is used as the preset external frequency pulse number. A display device having a frequency correction circuit for a display device as described in any one of items 1 to 4 of the patent application. A frequency correction method for a display device, which is implemented using a control circuit including a receiving unit, a frequency oscillator, a temperature detection module and a frequency tracking calculation unit. The method includes: driving the receiving unit to receive a Display a signal and generate an external frequency clock signal according to the display signal; drive the frequency oscillator to generate an internal frequency clock signal according to a control parameter; use the temperature detection module to obtain the current temperature of the control circuit; and drive the frequency chasing The calculation unit adjusts the control parameter according to the current temperature so that n times the frequency of the internal frequency clock signal is the same as the frequency of the external frequency clock signal, where n is a positive real number; where the temperature detection module has : a temperature sensor, used to obtain the current temperature; a temperature processing unit, used to convert the current temperature into a digital signal; and a temperature lookup table, which stores multiple temperature ranges and multiple counting times. A lookup table for mapping a corresponding counting time according to one of the temperature ranges to which the current temperature belongs. The frequency correction method for a display device as described in item 6 of the patent application, wherein the frequency tracking calculation unit counts the number of pulses of the internal frequency clock signal within a said counting time, and calculates the number of pulses based on the number of pulses. The control parameter is adjusted based on the comparison result between n times and an external frequency preset pulse number. The frequency correction method for a display device as described in item 7 of the patent application, wherein the frequency tracking calculation unit changes the control parameter when n times the number of pulses is different from the preset number of external frequency pulses. value to increase or decrease the frequency of the internal frequency clock signal. The frequency correction method for a display device as described in item 7 of the patent application, wherein the frequency tracking calculation unit counts the number of pulses of the external frequency clock signal within a said counting time, and calculates the frequency of the external frequency clock signal. The pulse number of the signal is used as the preset external frequency pulse number.

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