TWI819801B - 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; a control parameter storage unit that stores a comparison table of multiple temperature ranges and multiple preset control parameters; and a frequency tracking The calculation unit is used to map the comparison table according to the current temperature to obtain a corresponding preset control parameter when the external frequency clock signal does not exist, and determine the control according to the corresponding preset control parameter. parameters.

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, when the display signal stops transmitting, the frequency tracking mechanism cannot operate, causing the frequency of the internal frequency clock signal to drift due to the influence of temperature, thereby affecting the display quality.

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 to obtain a corresponding value, so that the frequency of a display driving clock signal and an external reference clock signal are The frequency is the same.

Another object of the present invention is to disclose a frequency correction method for a display device, which can store a plurality of preset values of the control parameters corresponding to a plurality of temperature ranges through a lookup table, so that the external reference clock can be When the signal does not exist, a corresponding preset value is obtained from the comparison table according to the value of the ambient temperature to determine the control parameter, thereby determining the frequency of the display driving clock signal.

Another object of the present invention is to disclose a frequency correction method for a display device, which can write different corresponding values of the control parameter obtained at different ambient temperatures into the comparison table, so that when the external reference clock signal is different, When present, the frequency of the display driving clock signal can be determined more accurately.

Another object of the present invention is to disclose a frequency correction circuit for a display device, which can make the display scanning of a display device not affected by changes in ambient temperature by executing the aforementioned method, and can perform the function when the external reference clock signal does not exist. The display device can maintain good display quality.

Another object of the present invention is to disclose a display device, which can use the aforementioned frequency correction circuit to make its display scan unaffected by changes in ambient temperature, and can maintain good performance of the display device when the external reference clock signal does not exist. Display quality.

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; a control parameter storage unit that stores a comparison table between a plurality of temperature ranges and a plurality of preset control parameters; and A frequency chasing calculation unit, used to map the comparison table according to the current temperature to obtain a corresponding preset control parameter when the external frequency clock signal does not exist, and determine based on the corresponding preset control parameter the control parameters.

In one embodiment, the frequency chasing calculation unit performs a frequency chasing calculation when the external frequency clock signal exists to obtain a corresponding value of the control parameter so that n times the frequency of the internal frequency clock signal is equal to the frequency of the external frequency clock signal. The frequencies of the frequency clock signals are the same, where n is a positive real number; and one of the preset control parameters corresponding to the current temperature in the comparison table is updated with the corresponding value.

In one embodiment, the temperature sensing module has: A temperature sensor to obtain the current temperature; and A temperature processing unit is used to convert the current temperature into a digital signal.

In one embodiment, the frequency chasing calculation includes: counting the number of pulses of the internal frequency clock signal within a counting time to obtain a first number, counting the number of pulses of the external frequency clock signal to obtain a second number, and The control parameter is adjusted according to the difference between n times the first number and the second number to increase or decrease the frequency of the internal frequency clock signal.

In one embodiment, the frequency oscillator is a voltage and current oscillator.

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 map a lookup table according to the current temperature to obtain a corresponding preset control parameter when the external frequency clock signal does not exist, and determine the control parameter according to the corresponding preset control parameter. .

In one embodiment, the frequency chasing calculation unit performs a frequency chasing calculation when the external frequency clock signal exists to obtain a corresponding value of the control parameter so that n times the frequency of the internal frequency clock signal is equal to the frequency of the external frequency clock signal. The frequencies of the frequency clock signals are the same, where n is a positive real number; and one of the preset control parameters corresponding to the current temperature in the comparison table is updated with the corresponding value.

In one embodiment, the temperature sensing module has: A temperature sensor to obtain the current temperature; and A temperature processing unit is used to convert the current temperature into a digital signal.

In one embodiment, the frequency chasing calculation includes: counting the number of pulses of the internal frequency clock signal within a counting time to obtain a first number, counting the number of pulses of the external frequency clock signal to obtain a second number, and The control parameter is adjusted according to the difference between n times the first number and the second number to increase or decrease the frequency of the internal frequency clock signal.

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 control parameter storage unit 114, a frequency tracking calculation unit 115 and a control unit 116. The temperature The sensor 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 row 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 115 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 control parameter storage unit 114 stores a lookup table of a plurality of temperature ranges and a plurality of preset control parameters to find one of the temperature ranges to which the current temperature belongs based on the value of the current temperature output by the control unit 116. The corresponding temperature range, and the comparison table is mapped according to the corresponding temperature range to obtain a corresponding preset control parameter Adj_t. Please refer to Table 1, which shows an example of the comparison table. Table 1 Temperature range (degrees C) Adj_tDefault value Adj_t update value Greater than or equal to -40 and less than -20 -30 -twenty four Greater than or equal to -20 and less than 0 -20 -17 Greater than or equal to 0 and less than 20 -10 -8 Greater than or equal to 20 and less than 40 0 1 Greater than or equal to 40 and less than 60 +10 +10 Greater than or equal to 60 and less than 80 +20 +20 Greater than or equal to 80 and less than 100 +30 +30 Greater than or equal to 100 and less than 120 +40 +40

The frequency tracking calculation unit 115 is used to map the comparison table according to the current temperature to obtain a corresponding preset control parameter Adj_t when the external frequency clock signal CK_W does not exist, and determine the control parameter Adj according to the corresponding preset control parameter Adj_t. . In addition, the frequency chasing calculation unit 115 performs a frequency chasing calculation when the external frequency clock signal CK_W exists to obtain a corresponding value of the control parameter Adj 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; and using the corresponding value to update a preset control parameter Adj_t corresponding to the current temperature in the comparison table, wherein the frequency chasing calculation includes: counting the internal frequency clock within a counting time The number of pulses of the signal CK_D is obtained to obtain a first number, the number of pulses of the external frequency clock signal CK_W is counted to obtain a second number, and the value of the control parameter Adj is adjusted according to the difference between n times the first number and the second number. To increase or decrease the frequency of the internal frequency clock signal CK_D, for example, when n times the first number is less than the second number, increase the value of the control parameter Adj to increase the frequency of the internal frequency clock signal CK_D; and in the first When n times the number is not less than the second number, the value of the control parameter Adj is reduced to reduce the frequency of the internal frequency clock signal CK_D.

As shown in Table 1, since the updated value of the preset control parameter Adj_t is 1 when the temperature is greater than or equal to 20 and less than 40, the original value 0 will be replaced by 1; when the temperature is greater than or equal to 0 and less than 20, the preset control parameter Adj_t is obtained. Assume that the updated value of the control parameter Adj_t is -8, and the original value -10 will be replaced by -8; when the temperature is greater than or equal to -20 and less than 0, the updated value of the preset control parameter Adj_t is -17, and the original value - 20 will be replaced by -17; and when the temperature is greater than or equal to -40 and less than -20, the updated value of the preset control parameter Adj_t is -24, and the original number -30 will be replaced by -24.

Please refer to FIG. 2 , which illustrates an operating waveform diagram of the frequency tracking calculation unit 115 . As shown in FIG. 2 , when the external frequency clock signal CK_W exists, the frequency chasing calculation unit 115 performs a frequency chasing calculation to obtain a value of the control parameter Adj and uses the value to update the preset corresponding to the current temperature in the comparison table. Control parameter Adj_t; and when the external frequency clock signal CK_W does not exist, the frequency chasing calculation unit 115 directly determines the value of the control parameter Adj using the preset control parameter Adj_t corresponding to the current temperature.

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 a frequency oscillator to generate an internal frequency clock according to a control parameter signal (step b); using a temperature detection module to obtain the current temperature of an environment (step c); and driving a frequency chasing calculation unit to map a lookup table according to the current temperature when the external frequency clock signal does not exist to obtain A corresponding preset control parameter, and the control parameter is determined according to the corresponding preset control parameter (step d).

In the above steps, the frequency chasing calculation unit performs a frequency chasing calculation when the external frequency clock signal exists to obtain a corresponding value of the control parameter so that n times the frequency of the internal frequency clock signal is equal to the frequency of the external frequency clock signal. The frequencies of the frequency clock signals are the same, where n is a positive real number; and one of the preset control parameters corresponding to the current temperature in the comparison table is updated with the corresponding value.

In addition, the temperature sensing module may have: a temperature sensor to obtain the current temperature; and a temperature processing unit to convert the current temperature into a digital signal.

In addition, the frequency chasing calculation may include: counting the number of pulses of the internal frequency clock signal within a counting time to obtain a first number, counting the number of pulses of the external frequency clock signal to obtain a second number, and according to the third number. The difference between n times a number and the second number adjusts the control parameter to increase or decrease the frequency of the internal frequency clock signal.

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 to obtain a corresponding value, 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 store multiple preset values of the control parameters corresponding to multiple temperature ranges through a lookup table, so that when the external reference clock signal does not exist, the The value of the ambient temperature is obtained from the comparison table to obtain a corresponding preset value to determine the control parameter, thereby determining the frequency of the display driving clock signal. 3. The frequency correction method for a display device of the present invention can write different corresponding values of the control parameters obtained under different ambient temperatures into the comparison table, so that the frequency correction method can be more accurate when the external reference clock signal does not exist. Determines the frequency of the display driving clock signal. 4. The frequency correction circuit for a display device of the present invention can perform the aforementioned method so that the display scan of a display device is not affected by changes in ambient temperature, and can maintain the display device when the external reference clock signal does not exist. Good display quality. 5. The display device of the present invention can use the aforementioned frequency correction circuit to prevent the display scan from being affected by changes in ambient temperature, and can maintain good display quality when the external reference clock signal does not exist.

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: Control parameter storage unit 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 a frequency oscillator to generate an internal frequency clock signal according to a control parameter Step c: Use a temperature detection module to obtain the current temperature of an environment (step d) Step d: Driving a frequency chasing calculation unit to map a lookup table according to the current temperature to obtain a corresponding preset control parameter when the external frequency clock signal does not exist, and determine the corresponding preset control parameter based on the corresponding preset control parameter. Described control parameters

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 a frequency oscillator to generate an internal frequency clock signal according to a control parameter

Step c: Use a temperature detection module to obtain the current temperature of an environment

Step d: Driving a frequency chasing calculation unit to map a lookup table according to the current temperature to obtain a corresponding preset control parameter when the external frequency clock signal does not exist, and determine the corresponding preset control parameter according to the corresponding preset control parameter. Described control parameters

Claims (10)

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; a control parameter storage unit that stores a comparison table of multiple temperature ranges and multiple preset control parameters; and a frequency tracking The calculation unit is respectively coupled to the receiving unit, the frequency oscillator, the temperature detection module and the control parameter storage unit, and is used to determine whether the external frequency clock signal is present in the display signal received by the receiving unit. The current temperature obtained by the temperature detection module maps the comparison table stored in the control parameter storage unit to obtain a corresponding preset control parameter, and determine the corresponding preset control parameter based on the corresponding preset control parameter. Control parameters to drive the frequency oscillator to generate the internal frequency clock signal. The frequency correction circuit for a display device as described in item 1 of the patent application, wherein the frequency chasing calculation unit performs a frequency chasing calculation when the external frequency clock signal exists to obtain a corresponding value of the control parameter. 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; and update one of the descriptions corresponding to the current temperature in the comparison table with the corresponding value Preset control parameters. The frequency correction circuit for a display device as described in item 1 of the patent application, wherein the temperature sensing module has: a temperature sensor to obtain the current temperature; and a temperature processing unit to to convert the current temperature into a digital signal. The frequency correction circuit for a display device as described in item 2 of the patent application, wherein the frequency chasing calculation includes: counting the number of pulses of the internal frequency clock signal within a counting time to obtain a first number, counting the The pulse number of the external frequency clock signal is used to obtain a second number, and the control parameter is adjusted according to the difference between n times the first number and the second number to increase or decrease the frequency of the internal frequency clock signal. The frequency correction circuit for a display device as described in item 1 of the patent application, wherein the frequency oscillator is a voltage and current oscillator. A display device having a frequency correction circuit for a display device as described in any one of items 1 to 5 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 When the external frequency clock signal does not exist, the calculation unit maps a lookup table according to the current temperature to obtain a corresponding preset control parameter, and determines the control parameter according to the corresponding preset control parameter. The frequency correction method for a display device as described in item 7 of the patent application, wherein the frequency chasing calculation unit performs a frequency chasing calculation when the external frequency clock signal exists to obtain a corresponding value of the control parameter So that n times the frequency of the internal frequency clock signal is equal to the frequency of the external frequency clock signal The rates are the same, where n is a positive real number; and one of the preset control parameters corresponding to the current temperature in the comparison table is updated with the corresponding value. The frequency correction method for a display device as described in item 7 of the patent application, wherein the temperature sensing module has: a temperature sensor to obtain the current temperature; and a temperature processing unit to to convert the current temperature into a digital signal. As described in item 8 of the patent application, the frequency correction method for a display device, wherein the frequency tracking calculation includes: counting the number of pulses of the internal frequency clock signal within a counting time to obtain a first number, counting the The pulse number of the external frequency clock signal is used to obtain a second number, and the control parameter is adjusted according to the difference between n times the first number and the second number to increase or decrease the frequency of the internal frequency clock signal.

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