CN1525429A - Device and method for dynamically adjusting discontinuous modal switching frequency value of liquid crystal display - Google Patents

Abstract

The invention discloses a method for dynamically adjusting a discontinuous mode switching frequency value of a liquid crystal display, which comprises the following steps of: receiving a scanning frequency value transmitted by a signal source end; (b) adjusting to obtain a switching frequency value of a discontinuous mode according to the scanning frequency value; and (c) transmitting the switching frequency value of the discontinuous mode to a lamp controller. The dynamic adjusting method of the invention can use a calculation method or a method of checking a corresponding table to adjust the switching frequency value. The switching frequency value is preferably a multiple of the sweep frequency value multiplied by (N +0.5), where N is a natural number, and the allowable range of the switching frequency value is + -20 Hz. The method of the present invention is used to dynamically adjust the optimal switching frequency value according to different scanning frequency values. Therefore, no matter any scanning frequency value is provided by the signal source end, the switching frequency value can be dynamically adjusted along with the scanning frequency value, so that the water ripple phenomenon is eliminated or reduced, and human eyes can not feel the water ripple phenomenon.

Description

Apparatus and method for dynamic adjustment of discontinuous mode switch frequency value for liquid crystal display

technical field

The present invention relates to a method and device for dynamically adjusting frequency, in particular, relates to a method and device for adjusting frequency value of a discontinuous mode switch of a liquid crystal display.

Background technique

Most of the current liquid crystal displays use cold-cathode lamps (CCFL) as the backlight source, so they must be driven by high-voltage alternating current and change the ratio of switching time (Duty cycle) to change the brightness. Referring to FIG. 1 , in a liquid crystal display, usually a controller 11 and an inverter 12 must be used to light the lamp 13 of the liquid crystal display and control the brightness of the lamp 13 . The controller 11 can be configured separately from the switching circuit 12, or combined with the switching circuit 12 as a module.

Referring to FIG. 2A and FIG. 2B, there are two modes for lighting the lamp and controlling the brightness of the lamp: continuous mode (Continuous Mode) and discontinuous mode (Burst Mode). The waveform of the control signal in the continuous mode is shown in FIG. 2A . The frequency of the control signal in the continuous mode is 30-70 KHz, and the amplitude of the control signal is used to adjust the brightness of the lamp.

The control waveform of the discontinuous mode is shown in Figure 2B, the control signal frequency of the discontinuous mode is also 30-70KHz, the control signal of the discontinuous mode has a switching frequency of about 100-500Hz, and the control signal The ratio of the switching time of the waveform (Duty cycle) to adjust the brightness of the lamp.

At present, most liquid crystal displays adopt discontinuous mode control mode, and the switching frequency varies according to the design of each manufacturer, and is fixed at a certain switching frequency value. The liquid crystal display must receive a scanning frequency value transmitted by a signal source to scan the screen image. The signal source can be set by the display card of the computer or the software of the computer, so the scanning frequency is not fixed. . However, at certain scanning frequency values, there will be water ripple phenomenon (water flow) that can be observed by human eyes, and due to different scanning frequency values, the water ripple sometimes scrolls up and sometimes scrolls down. The speed of scrolling also varies. According to the experiment, the phenomenon of water ripple should be related to the scanning frequency and switching frequency.

Therefore, it is necessary to provide an innovative and progressive technology for dynamically adjusting the switching frequency value of the discontinuous mode to solve the above problems.

Contents of the invention

The purpose of the present invention is to provide a method for dynamic adjustment of the discontinuous mode switching frequency value of liquid crystal display, comprising the following steps: (a) receiving a scanning frequency value transmitted by a signal source; (b) according to the Scanning the frequency value to adjust a discontinuous mode switching frequency value; and (c) sending the discontinuous mode switching frequency value to a lamp controller.

In the dynamic adjustment method of the present invention, the switching frequency value can be adjusted by calculating or looking up a corresponding table. The optimal value of the switching frequency is a multiple of (N+0.5) multiplied by the scanning frequency, N is a natural number, and the allowable range of the switching frequency is ±20Hz. The method of the present invention dynamically adjusts the best switching frequency value according to different scanning frequency values. Therefore, regardless of any scanning frequency value provided by the signal source, the switching frequency value is dynamically adjusted accordingly to eliminate or reduce the water ripple phenomenon, so that the human eye will not feel the water ripple phenomenon.

Description of drawings

Fig. 1 is a schematic diagram of controlling the lighting and brightness of the lamp tube in the liquid crystal display;

Fig. 2A is a control signal waveform diagram of a continuous mode;

Fig. 2B is a waveform diagram of a control signal in a discontinuous mode;

Fig. 3 is the flow chart of the method for dynamically adjusting the discontinuous mode switching frequency value of the liquid crystal display of the present invention; and

FIG. 4 is a schematic diagram of a device for dynamically adjusting switching frequency values in a discontinuous mode for a liquid crystal display according to the present invention.

Symbol Description

11: Controller

12: Switching circuit

13: Lamp tube

40: The present invention's discontinuous mode switching frequency value dynamic adjustment device

41: Receiver

42: Regulator

43: Teleporter

50: Signal source terminal

60: Lamp controller

Detailed ways

Please refer to FIG. 3 , which shows a flow chart of the method for dynamically adjusting the switching frequency value of the liquid crystal display in discontinuous mode according to the present invention. First in step 31, the liquid crystal display receives a scanning frequency value sent by a signal source to scan the screen, the signal source can be the setting of the display card of the computer or the software setting of the computer, so The scanning frequency value is not fixed. According to the setting of general operators, the scanning frequency value is usually 60 Hz, 70.7 Hz, 75.03 Hz, 59.94 Hz, 72.8 Hz, 75 Hz, 56.25 Hz, 60.32 Hz, 66.67 Hz, etc.

In step 32, a switching frequency value of the discontinuous mode is dynamically adjusted according to the scanning frequency value. The dynamic adjustment method of the present invention can use a calculation method to calculate the switching frequency of the discontinuous mode according to the scanning frequency value. The calculation method is to multiply the scanning frequency value by a multiple of (N+0.5) to calculate the switching frequency value of the discontinuous mode, wherein N is a natural number. Moreover, the allowable range of the switching frequency value of the discontinuous mode is ±20Hz.

Using an embodiment to illustrate, if the scanning frequency is 60Hz and N=3, then the switching frequency can be calculated to be 210Hz (60×3.5), and the allowable range is ±20Hz, but the best is ±10Hz . Therefore, the optimal range of the switching frequency value is 210Hz±10Hz, that is, the optimal range of the switching frequency value is between 200Hz and 220Hz.

In addition, the switching frequency of the discontinuous mode can be multiplied by an integer multiple of the scanning frequency value. The allowable range of switching frequency for this discontinuous mode is ±3Hz.

Another embodiment is used to illustrate that if the scanning frequency value is 75Hz and the integer multiple is 3, then the switching frequency value can be calculated to be 225Hz (75×3), and the allowable range is ±3Hz, but the most The best is ±1Hz. Therefore, the optimal range of the switching frequency value is 225Hz±1Hz, that is, the optimal range of the switching frequency value is between 224Hz and 226Hz.

The dynamic adjustment method of the present invention is not limited to the above-mentioned method that must be calculated, and a corresponding table can also be used to store the calculated switching frequency value and the corresponding scanning frequency value in advance, and obtain correspondingly according to the received scanning frequency value. The switching frequency value for this discontinuous mode.

In step 33, the switching frequency is sent to a lamp controller. The lamp controller transmits a control waveform to the lamp according to the switching frequency value, so as to light the lamp and control the brightness of the lamp.

The method of the present invention dynamically adjusts the optimal switching frequency value according to different scanning frequency values, so as to improve the prior art and fix the defect of the switching frequency value. Therefore, regardless of any scanning frequency value provided by the signal source end, the switching frequency value is dynamically adjusted accordingly, which can eliminate or reduce the water ripple phenomenon, so that human eyes will not feel the water ripple phenomenon.

Referring to FIG. 4 , it shows a device 40 for dynamically adjusting the discontinuous mode switching frequency value of a liquid crystal display according to the present invention, which includes: a receiver 41 , an adjuster 42 and a transmitter 43 . The receiver 41 is used for receiving a scanning frequency value transmitted by a signal source 50 . The adjuster 42 is used for dynamically adjusting a switching frequency value of a discontinuous mode according to the scanning frequency value received by the receiver 41 . The transmitter 43 is used for transmitting the switching frequency value of the discontinuous mode to a lamp controller 60 .

The adjuster 42 further includes a frequency multiplication circuit, which is used to multiply the scanning frequency by a multiple of (N+0.5) to obtain the switching frequency of the discontinuous mode by multiplying the scanning frequency, wherein N is a Natural number. Moreover, the allowable range of the switching frequency value of the discontinuous mode is ±20Hz.

The adjuster 42 can also use a frequency division circuit, according to the scanning frequency value and a high-frequency signal, the switching frequency value of the discontinuous mode is (N+0.5) multiple of the scanning frequency value with the frequency dividing circuit , where N is a natural number.

In addition, the adjuster 42 can use the above-mentioned frequency multiplying circuit or frequency dividing circuit to make the switching frequency of the discontinuous mode an integer multiple of the scanning frequency. At this time, the allowable range of the switching frequency value of the discontinuous mode is ±3Hz.

Moreover, the adjuster 42 can use a database to store the corresponding table data of the scanning frequency value and the calculated switching frequency value of the discontinuous mode, so as to obtain the corresponding switching frequency value of the discontinuous mode according to the received scanning frequency value. State switching frequency value.

After the dynamic adjustment by the adjuster 42 , the optimal switching frequency value is obtained, and the switching frequency value is transmitted to the lamp controller 60 by the transmitter 43 . The lamp controller 60 transmits a control waveform to the lamp according to the switching frequency value, so as to light the lamp and control the brightness of the lamp. Please refer to FIG. 1 again. The lamp controller 60 in FIG. 4 is the same as the controller 11 in FIG. 1 , and it can be separated from the switching circuit 12 or combined with the switching circuit 12 into a module.

The device 40 of the present invention can use the adjuster 42 to dynamically adjust the optimal switching frequency value according to different scanning frequency values, so as to improve the water ripple phenomenon caused by the fixed switching frequency value in the prior art. Therefore, regardless of any scanning frequency value transmitted at the signal source terminal 50, the adjuster 42 will dynamically adjust the switching frequency value according to different scanning frequency values. With the cooperation of the appropriate scanning frequency value and switching frequency value, that is It can eliminate or reduce the water ripple phenomenon, so that the human eyes will not feel the water ripple phenomenon.

The above-mentioned embodiments are only to illustrate the principles and effects of the present invention, but not to limit the present invention. Therefore, those skilled in the art can make modifications and changes to the above-mentioned embodiments without departing from the spirit of the present invention. The scope of rights of the present invention should be listed in the claims.

Claims (14)

1. a method for the dynamic adjustment of the discontinuous mode switching frequency value of liquid crystal display, it is characterized in that, may further comprise the steps: (a) receiving a scanning frequency value transmitted by a signal source; (b) According to the scanning frequency value, adjust the switching frequency value of a discontinuous mode; and (c) Sending the switching frequency value of the discontinuous mode to a lamp controller. 2. The method according to claim 1, wherein the step (b) is a calculation method, and the switching frequency value of the discontinuous mode is calculated according to the scanning frequency value. 3. The method according to claim 2, wherein the switching frequency value of the discontinuous mode is a multiple of (N+0.5) multiplied by the scanning frequency value, wherein N is a natural number. 4. The method according to claim 3, wherein the allowable range of the switching frequency of the discontinuous mode is ±20 Hz. 5. The method as claimed in claim 2, wherein the switching frequency value of the discontinuous mode is the scanning frequency value multiplied by an integer multiple. 6. The method according to claim 5, wherein the allowable range of the switching frequency of the discontinuous mode is ±3 Hz. 7. The method according to claim 1, wherein in the step (b), the switching frequency value of the discontinuous mode is correspondingly obtained by looking up a corresponding table according to the scanning frequency value. 8. A device for dynamically adjusting the discontinuous mode switching frequency value of a liquid crystal display, characterized in that it comprises: a receiver for receiving a scanning frequency value transmitted by a signal source; a regulator, electrically connected to the receiver, for adjusting a switching frequency value of a discontinuous mode according to the scanning frequency value; and A transmitter, electrically connected to the regulator, is used to transmit the switching frequency value of the discontinuous mode to a lamp controller. 9. The device according to claim 8, wherein the adjuster further comprises a frequency multiplying circuit for multiplying the scanning frequency value by a multiple of (N+0.5) to obtain the non- The switching frequency value of continuous mode, where N is a natural number. 10. The device according to claim 8, wherein the adjuster further comprises a frequency division circuit for making the discontinuous mode The switching frequency value is a (N+0.5) multiple of the scanning frequency value, where N is a natural number. 11. The device according to claim 9 or 10, wherein the allowable range of the switching frequency of the discontinuous mode is ±20 Hz. 12. The device according to claim 9 or 10, wherein the switching frequency value of the discontinuous mode is the scanning frequency value multiplied by an integer multiple. 13. The device as claimed in claim 12, wherein the allowable range of the switching frequency of the discontinuous mode is ±3 Hz. 14. The method as claimed in claim 8, wherein the adjuster further comprises a database for storing the corresponding table data of the scanning frequency value and the discontinuous mode switching frequency value.

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