Display device

Abstract

The utility model discloses a display device, which comprises a display panel, a time schedule controller and a voltage conversion circuit, and is characterized in that the time schedule controller comprises a control signal output end and is used for detecting image data of a current frame picture displayed by the display panel; outputting a control signal through a control signal output end under the condition that the image data is preset image data; the voltage conversion circuit comprises a voltage conversion chip, a frequency control unit and a power voltage output end, the voltage conversion chip comprises a switching frequency control pin, and the frequency control unit is electrically connected with the switching frequency control pin and the control signal output end. The frequency control unit is used for adjusting the magnitude of the voltage transmitted to the switching frequency control pin according to the control signal, and the voltage conversion chip is used for controlling the frequency of the power voltage output by the power voltage output end according to the magnitude of the voltage received by the switching frequency control pin. The utility model aims to avoid the squeal problem of the display device.

Description

Technical Field

[0001] This application relates to the field of display technologies, and particularly to a display device. Background Art

[0002] In existing display devices, there are a voltage conversion circuit and a ceramic multilayer capacitor. The voltage conversion circuit is used to convert an input voltage into various voltages required for a display panel to display an image. Among them, the output terminal of the voltage conversion circuit is provided with the ceramic multilayer capacitor, and the ceramic multilayer capacitor is used for filtering. When the voltage output by the voltage conversion circuit does not match the load of the image displayed on the display panel, the ceramic multilayer capacitor will make a whistling sound due to an increase in the ripple. Summary of the Invention

[0003] An embodiment of this application provides a display device, aiming to avoid the whistling problem of the display device.

[0004] On the one hand, an embodiment of this application provides a display device, including: a display panel, a timing controller, and a voltage conversion circuit. The timing controller includes a control signal output terminal. The timing controller is used to detect the image data of the current frame image displayed on the display panel, and output a control signal through the control signal output terminal when the image data is preset image data; the voltage conversion circuit includes a voltage conversion chip, a frequency control unit, and a power supply voltage output terminal. The voltage conversion chip includes a switching frequency control pin. The frequency control unit is electrically connected to the switching frequency control pin and the control signal output terminal. The frequency control unit is used to adjust the magnitude of the voltage transmitted to the switching frequency control pin according to the control signal. The voltage conversion chip is used to control the frequency of the power supply voltage output by the power supply voltage output terminal according to the magnitude of the voltage received by the switching frequency control pin.

[0005] Optionally, in some embodiments of this application, the frequency control unit includes a first resistor, a second resistor, and a first switching element. The first end of the first resistor is electrically connected to the ground terminal. The second end of the first resistor is electrically connected to the first end of the second resistor. The second end of the second resistor is electrically connected to the switching frequency control pin. The first switching element is arranged in parallel with the second resistor. The first switching element is used to conduct or disconnect under the control of the control signal.

[0006] Optionally, in some embodiments of this application, the resistance value of the first resistor is less than or equal to the resistance value of the second resistor.

[0007] Optionally, in some embodiments of this application, the first switching element is an N-type transistor or a P-type transistor.

[0008] Optionally, in some embodiments of the present application, the timing controller includes an acquisition module, a judgment module, and a control module. The acquisition module is configured to acquire the image data of the current frame of the picture. The judgment module is configured to judge whether the current frame of the picture is an overloaded picture according to the image data. The control module is configured to control the control signal output terminal to output the control signal for turning on the first switching element when the current frame of the picture is the overloaded picture.

[0009] Optionally, in some embodiments of the present application, the control module is further configured to control the control signal output terminal to output the control signal for turning off the first switching element when the current frame of the picture is a lightly loaded picture.

[0010] Optionally, in some embodiments of the present application, the voltage conversion chip includes a switching unit. The voltage conversion chip controls the conduction frequency of the switching unit according to the magnitude of the voltage received by the switching frequency control pin. The conduction frequency of the switching unit is equal to the frequency of the power supply voltage output by the power supply voltage output terminal.

[0011] Optionally, in some embodiments of the present application, the conduction frequency of the switching unit when the first switching element is turned on is higher than the conduction frequency of the switching unit when the first switching element is turned off.

[0012] Optionally, in some embodiments of the present application, the switching unit includes a second switching element. The voltage conversion chip controls the conduction frequency of the second switching element according to the magnitude of the voltage received by the switching frequency control pin.

[0013] Optionally, in some embodiments of the present application, the voltage conversion circuit is a buck circuit, and the buck circuit is configured to output a digital power supply voltage.

[0014] Optionally, in some embodiments of the present application, the value of the digital power supply voltage ranges from 1 volt to 2 volts.

[0015] The display device provided by the present application includes: a display panel, a timing controller, and a voltage conversion circuit. The timing controller includes a control signal output terminal. The timing controller is configured to detect the image data of the current frame displayed on the display panel, and output a control signal through the control signal output terminal when the image data is preset image data. The voltage conversion circuit includes a voltage conversion chip, a frequency control unit, and a power supply voltage output terminal. The voltage conversion chip includes a switching frequency control pin. The frequency control unit is electrically connected to the switching frequency control pin and the control signal output terminal. The frequency control unit is configured to adjust the magnitude of the voltage transmitted to the switching frequency control pin according to the control signal. The voltage conversion chip is configured to control the frequency of the power supply voltage output by the power supply voltage output terminal according to the magnitude of the voltage received by the switching frequency control pin. That is, the display device provided by the present application realizes the adjustment of the operating frequency of the voltage conversion circuit by setting a frequency control unit at the input end of the switching frequency control pin. The frequency control unit adjusts the magnitude of the voltage transmitted to the switching frequency control pin under the control of the control signal output by the timing controller. The voltage conversion chip controls the frequency of the power supply voltage output by the power supply voltage output terminal according to the magnitude of the voltage received by the switching frequency control pin, so as to ensure that the operating frequency of the voltage conversion circuit is not within the operating frequency range that causes the ceramic multilayer capacitor to whistle, and avoid the whistling problem of the display device. Description of the Drawings

[0016] Figure 1 is a schematic diagram of the display device provided by the embodiment of the present application;

[0017] Figure 2 is Figure 1 a partial schematic diagram of the voltage conversion circuit in the provided display device. Detailed Embodiments

[0018] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application. The described technical solutions are only used to explain and illustrate the idea of the present application, and should not be regarded as a limitation on the protection scope of the present application.

[0019] Each embodiment input in the present application is similar, and the features in different embodiments can be combined with each other.

[0020] During the operation of a Liquid Crystal Display (LCD), multiple operating voltages are required. These operating voltages are typically obtained by transforming the input voltage through a power management integrated circuit in the drive circuit. Among them, the Boost circuit and the Buck circuit are the two most basic circuits in the power management integrated circuit. The Boost circuit can boost the input voltage to obtain the analog power supply voltage AVDD, and the Buck circuit can step down the input voltage to obtain the digital power supply voltage DVDD.

[0021] Currently, in a buck circuit with a Pulse Frequency Modulation (PFM) control mode, it is easier to cause the ceramic multilayer capacitor to emit a whistling sound. First, buck products have a PFM control mode. In this control mode, as the load of the buck product increases, its operating frequency enters the range of 20 Hz - 20 kHz. Second, the output ripple of buck products is generally relatively small. That is, for a ceramic multilayer capacitor to emit a whistling sound, two conditions must be met simultaneously: the first is that the ripple amplitude across the capacitor is large, and the second is that the frequency of the ripple across the capacitor is in the range of 20 Hz - 20 kHz.

[0022] As Figure 1 and Figure 2 shown, an embodiment of the present application provides a display device 100, including: a display panel (not shown in the figure), a timing controller 110, and a voltage conversion circuit 120. The timing controller 110 includes a control signal output terminal GPIO. The timing controller 110 is configured to detect the image data of the current frame of the picture, and output a control signal through the image data control signal output terminal GPIO when the image data is preset image data. The voltage conversion circuit 120 includes a voltage conversion chip 121, a frequency control unit 122, and a power supply voltage output terminal DVDD. The voltage conversion chip 121 includes a switching frequency control pin RT. The frequency control unit 122 is electrically connected to the switching frequency control pin RT and the control signal output terminal GPIO respectively. The frequency control unit 122 is configured to adjust the magnitude of the voltage transmitted to the switching frequency control pin RT according to the control signal. The voltage conversion chip 121 controls the frequency of the power supply voltage output from the power supply voltage output terminal DVDD according to the magnitude of the voltage received by the switching frequency control pin RT.

[0023] In the display device provided by the present application, by arranging a frequency control unit 122 at the input end of the switching frequency control pin RT, the frequency control unit 122 adjusts the magnitude of the voltage transmitted to the switching frequency control pin RT under the control of the control signal output by the timing controller 110, and the voltage conversion chip 121 outputs the frequency of the power supply voltage at the power supply voltage output terminal DVDD according to the magnitude of the voltage received by the switching frequency control pin RT, that is, the adjustment of the operating frequency of the voltage conversion circuit 120 is realized, ensuring that the operating frequency of the voltage conversion circuit 120 does not fall within the operating frequency range that causes the ceramic multilayer capacitor to emit a whistling sound, and avoiding the whistling problem of the display device.

[0024] In an embodiment of the present application, the voltage conversion circuit 120 is a buck circuit, and the voltage conversion chip 121 is used to output a digital power supply voltage. Among them, the value of the digital power supply voltage ranges from 1 volt to 2 volts. Specifically, the values of the digital power supply voltage include 1 volt, 1.1 volts, 1.2 volts, 1.3 volts, 1.4 volts, 1.5 volts, 1.6 volts, 1.7 volts, 1.8 volts, 1.9 volts, 2 volts. Preferably, the buck circuit is used to output a digital power supply voltage of 1.1 volts or 1.8 volts.

[0025] In an embodiment of the present application, the frequency control unit 122 includes a first resistor R1, a second resistor R2, and a first switching element T1. The first end of the first resistor R1 is electrically connected to the ground terminal GND, the second end of the first resistor R1 is electrically connected to the first end of the second resistor R2, the second end of the second resistor R2 is electrically connected to the switching frequency control pin RT, the first switching element T1 is arranged in parallel with the second resistor R2, and the first switching element T1 is used to conduct or disconnect under the control of the control signal.

[0026] In an embodiment of the present application, the first switching element T1 can be a transistor or other types of switching devices. Figure 1 Taking the first switching element T1 as an N-type transistor as an example. The second end of the first resistor R1 is electrically connected to one of the source and drain of the first switching element T1, the second end of the second resistor R2 is electrically connected to the other of the source and drain of the first switching element T1, and the gate of the first switching element T1 is electrically connected to the control signal output terminal GPIO.

[0027] In an embodiment of the present application, the resistance value of the first resistor R1 is less than or equal to the resistance value of the second resistor R2. Specifically, the difference between the resistance value of the first resistor R1 and the resistance value of the second resistor R2 is between 0 ohms and 200 ohms. The values of the difference between the resistance value of the first resistor R1 and the resistance value of the second resistor R2 include 0 ohms, 10 ohms, 20 ohms, 30 ohms, 40 ohms, 50 ohms, 60 ohms, 70 ohms, 80 ohms, 90 ohms, 100 ohms, 110 ohms, 120 ohms, 130 ohms, 140 ohms, 150 ohms, 160 ohms, 170 ohms, 180 ohms, 190 ohms, and 200 ohms.

[0028] In an embodiment of the present application, the first switching element T1 is an N-type transistor or a P-type transistor. Preferably, the first switching element T1 is an N-type transistor.

[0029] In an embodiment of the present application, the timing controller 110 includes an acquisition module, a judgment module, and a control module. Among them, the acquisition module is used to acquire the image data of the current frame of the picture. The judgment module is used to judge whether the current frame of the picture is an overloaded picture according to the image data.

[0030] Among them, in an overloaded picture, the data voltage frequently switches between a high level and a low level, so that the display brightness of several consecutive rows of sub-pixels frequently switches between a low brightness and a high brightness.

[0031] Specifically, the control module is used to control the control signal output terminal GPIO to output a signal for turning on the first switching element T1 when the current frame of the picture is an overloaded picture. The preset image data is the image data of an overloaded picture or the image data of a lightly loaded picture.

[0032] Specifically, when the first switching element T1 is an N-type transistor, the control module is used to control the control signal output terminal GPIO to output a high-level control signal when the current frame of the picture is an overloaded picture, and the first switching element T1 is turned on under the control of the high-level control signal.

[0033] Alternatively, when the first switching element T1 is a P-type transistor, the control module is used to control the control signal output terminal GPIO to output a low-level control signal when the current frame of the picture is an overloaded picture, and the first switching element T1 is turned on under the control of the low-level control signal.

[0034] In an embodiment of the present application, the control module is further configured to control the control signal output terminal GPIO to output a control signal for turning off the first switching element T1 when the current frame picture is a light load picture. Specifically, when the first switching element T1 is an N-type transistor, the control module is further configured to control the control signal output terminal GPIO to output a control signal with a low level when the current frame picture is a light load picture, and the first switching element T1 is turned off under the control of the control signal with a low level.

[0035] Alternatively, when the first switching element T1 is a P-type transistor, the control module is further configured to control the control signal output terminal GPIO to output a high-level control signal when the current frame picture is a light load picture, and the first switching element T1 is turned off under the control of the high-level control signal.

[0036] In an embodiment of the present application, the voltage conversion chip 121 includes a switching unit 1211. The voltage conversion chip 121 controls the conduction frequency of the switching unit 1211 according to the magnitude of the voltage received by the switching frequency control pin RT, and the conduction frequency of the switching unit 1211 is equal to the frequency of the power supply voltage output by the power supply voltage output terminal DVDD.

[0037] In an embodiment of the present application, the conduction frequency of the switching unit 1211 when the first switching element T1 is conducting is higher than the conduction frequency of the switching unit 1211 when the first switching element T1 is turned off. Specifically, when the first switching element T1 is an N-type transistor and the current frame picture is a heavy load picture, the control signal output terminal GPIO is controlled to output a control signal with a high level. The first switching element T1 is turned on under the control of the control signal with a high level, the second resistor R2 is open-circuited, and the ground voltage input from the ground terminal GND flows through the first resistor R1 and the first switching element T1 and then is input to the switching frequency control pin RT. At this time, the switching frequency control pin RT is connected to the first ground voltage. When the first switching element T1 is an N-type transistor and the current frame picture is a light load picture, the control signal output terminal GPIO is controlled to output a control signal with a low level. The first switching element T1 is turned off under the control of the control signal with a low level, and the ground voltage input from the ground terminal GND flows through the first resistor R1 and the second resistor R2 and then is input to the switching frequency control pin RT. At this time, the switching frequency control pin RT is connected to the second ground voltage. Among them, the first ground voltage is greater than the second ground voltage. When the switching frequency control pin RT is connected to the first ground voltage, the switching unit 1211 is controlled to conduct at a first frequency. When the switching frequency control pin RT is connected to the second ground voltage, the switching unit 1211 is controlled to conduct at a second frequency, where the first frequency is greater than the second frequency.

[0038] Such as Figure 1 and Figure 2As shown, the switching unit 1211 includes a second switching element T2, and the voltage conversion chip 121 controls the conduction frequency of the second switching element T2 according to the magnitude of the voltage received by the switching frequency control pin RT. Preferably, the second switching element T2 is an N-type transistor or a P-type transistor.

[0039] Specifically, when the switching frequency control pin RT is connected to the first ground voltage, it controls the second switching element T2 to conduct at the first frequency, and when the switching frequency control pin RT is connected to the second ground voltage, it controls the second switching element T2 to conduct at the second frequency, so that the conduction frequency of the second switching element T2 is higher when the first switching element T1 is conducting than when the first switching element T1 is off.

[0040] As Figure 2 shown, the voltage conversion circuit 120 further includes M load resistors RM1 - RMM and P switches KP1 - KPP, where M and P are positive integers greater than or equal to 2.

[0041] In an embodiment of the present application, the voltage conversion circuit 120 further includes a voltage input terminal Vin, an inductor L1, a second switching element T2, a diode D1, and a capacitor C1. One of the source and drain of the second switching element T2 is electrically connected to the voltage input terminal Vin, and the voltage input terminal Vin is used to connect an input voltage. The other of the source and drain of the second switching element T2 is electrically connected to the cathode of the diode D1 and one end of the load resistors RM1 - RMM, and the gate of the second switching element T2 is the control terminal. The other ends of the load resistors RM1 - RMM are respectively electrically connected to one ends of the switches KP1 - KPP. The other ends of the switches KP1 - KPP are all electrically connected to one end of the connected inductor L1. The other end of the inductor L1 is electrically connected to the first plate of the capacitor C1. The second plate of the capacitor C1 is electrically connected to the ground terminal GND. And the other end of the inductor L1 is the voltage output terminal of the voltage conversion circuit 120, and the voltage output terminal outputs a digital power supply voltage DVDD.

[0042] Specifically, the input voltage is input from one of the source and drain of the second switching element T2. When the second switching element T2 is turned on and any one or more of the switches are closed, the input voltage charges the inductor L1, and the current of the inductor L1 linearly rises until it tends to be stable. At this time, the diode D1 is reversely cut off. When the second switching element T2 is turned off, the diode D1 is forward-conducted, and the inductor L1, the capacitor C1, and the diode D1 form a loop. The current of the inductor L1 gradually decreases, and the voltage across the capacitor C1 also gradually decreases, obtaining an output voltage lower than the input voltage. This output voltage can be used as the digital power supply voltage DVDD in the liquid crystal driving circuit. The load resistors RM1 - RMM are connected to the second switching element T2. When the switching states of the switches KP1 - KPP change, the resistance value of the resistor connected to the second switching element T2 changes accordingly, thereby changing the conduction frequency of the second switching element T2. Therefore, when the switching frequency control pin RT is connected to the first ground voltage, the states of the switches KP1 - KPP are adjusted to control the second switching element T2 to conduct at the first frequency. When the switching frequency control pin RT is connected to the second ground voltage, the states of the switches KP1 - KPP are adjusted to control the switching unit 1211 to conduct at the second frequency.

[0043] Specifically, other field effect transistors or triodes can also be used for the second switching element T2. In specific implementation, the resistance values of the load resistors RM1 - RMM and the value of M can be set according to the circuit requirements. In some feasible implementation manners, M = 3 can be taken. The resistance values of any two of the load resistors RM1 - RMM can be the same or different. The switching states of any two of the switching transistors KM1 - KPP can be the same or different. For example, one or more of the switching transistors KM1 - KPP can be closed simultaneously.

[0044] In the display device provided by the present application, by setting the frequency control unit 122 at the input end of the switching frequency control pin RT, the frequency control unit 122 adjusts the magnitude of the voltage transmitted to the switching frequency control pin RT under the control of the control signal output by the timing controller 110. The voltage conversion chip 121 outputs the frequency of the power supply voltage at the power supply voltage output end DVDD according to the magnitude of the voltage received by the switching frequency control pin RT, that is, the working frequency of the voltage conversion circuit 120 is adjusted, ensuring that the working frequency of the voltage conversion circuit 120 is not within the working frequency range that causes the ceramic multilayer capacitor to whistle, and avoiding the whistling problem of the display device.

[0045] The above has introduced in detail a display device provided by the embodiments of the present application. The description of the above embodiments is only used to help understand the core idea of the present application. The above description should not be construed as a limitation on the protection scope of the present application.

Claims

1. A display device, characterized in that: include: Display panel; A timing controller, the timing controller comprising a control signal output terminal, the timing controller being used to detect image data of a current frame displayed by the display panel, and outputting a control signal through the control signal output terminal when the image data is preset image data; A voltage conversion circuit, the voltage conversion circuit includes a voltage conversion chip, a frequency control unit and a power supply voltage output end, the voltage conversion chip includes a switching frequency control pin, the frequency control unit is electrically connected to the switching frequency control pin and the control signal output end, the frequency control unit is used to adjust the size of the voltage transmitted to the switching frequency control pin according to the control signal, and the voltage conversion chip is used to control the frequency of the power supply voltage output by the power supply voltage output end according to the size of the voltage received by the switching frequency control pin.

2. The display device according to claim 1, characterized in that The frequency control unit includes a first resistor, a second resistor and a first switch element; The first end of the first resistor is electrically connected to the ground end, the second end of the first resistor is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the switching frequency control pin, the first switching element is arranged in parallel with the second resistor, and the first switching element is used to be turned on or off under the control of the control signal.

3. The display device according to claim 2, characterized in that: The resistance value of the first resistor is less than or equal to the resistance value of the second resistor.

4. The display device according to claim 2, characterized in that: The timing controller includes an acquisition module, a judgment module and a control module. The acquisition module is used to acquire image data of the current frame image. The judgment module is used to judge whether the current frame image is a reloaded image based on the image data. The control module is used to control the control signal output end to output the control signal that turns on the first switching element when the current frame image is the reloaded image.

5. The display device according to claim 4, characterized in that: The control module is further configured to control the control signal output terminal to output the control signal for turning off the first switch element when the current frame image is a light-load image.

6. The display device according to claim 2, characterized in that: The voltage conversion chip includes a switch unit, and the voltage conversion chip controls the conduction frequency of the switch unit according to the magnitude of the voltage received by the switch frequency control pin. The conduction frequency of the switch unit is equal to the frequency of the power supply voltage output by the power supply voltage output terminal.

7. The display device according to claim 6, characterized in that: The frequency at which the switch unit is turned on when the first switch element is turned on is higher than the frequency at which the switch unit is turned on when the first switch element is turned off.

8. The display device according to claim 6, characterized in that: The switch unit includes a second switch element, and the voltage conversion chip controls the conduction frequency of the second switch element according to the magnitude of the voltage received by the switch frequency control pin.

9. The display device according to claim 1, characterized in that: The voltage conversion circuit is a step-down circuit, and the step-down circuit is used to output a digital power supply voltage.

10. The display device according to claim 9, characterized in that: The digital power supply voltage has a value between 1V and 2V.

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