CN110010089B - Backlight driving circuit and driving method, backlight module and display module - Google Patents
Backlight driving circuit and driving method, backlight module and display module Download PDFInfo
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- CN110010089B CN110010089B CN201910453004.8A CN201910453004A CN110010089B CN 110010089 B CN110010089 B CN 110010089B CN 201910453004 A CN201910453004 A CN 201910453004A CN 110010089 B CN110010089 B CN 110010089B
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- 238000005070 sampling Methods 0.000 claims abstract description 51
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- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
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Abstract
The disclosure relates to the technical field of display, and provides a backlight driving circuit which comprises a sampling hold circuit, a voltage detection unit, a counter and a processing unit. The input end of the sampling hold circuit is connected with the reference voltage generating unit, and the output end of the sampling hold circuit is connected with the driving voltage generating unit; the voltage detection unit is connected with the reference voltage generation unit and used for outputting an effective level signal when the reference voltage changes; the counter is connected with the voltage detection unit and used for collecting the triggering times of the effective level signal; the processing unit is connected with the counter and the control end of the sampling and holding circuit and is used for outputting a control signal to the control end of the sampling and holding circuit according to the triggering times of the effective level signal acquired by the counter; when the number of times of triggering the effective level signal is less than three times, the control signal is a holding signal, and when the number of times of triggering the effective level signal is equal to three times, the control signal is a sampling signal. The backlight driving circuit can avoid the phenomenon of screen flashing when the frequency of the pulse width modulation signal changes.
Description
Technical Field
The invention relates to the technical field of display, in particular to a backlight driving circuit, a driving method, a backlight module and a display module.
Background
In the field of Display technology, a Liquid Crystal panel of a Liquid Crystal Display (LCD) cannot generate a light source, and the LCD needs to provide the light source by using a backlight module located at the back of the Liquid Crystal panel. Because Light Emitting Diodes (LEDs) can improve the color rendering capability of the panel and are environmentally friendly, most backlight modules use LEDs as Light Emitting elements.
In the related art, the backlight module generally drives the LEDs in the backlight module through a backlight driving circuit to achieve LED light emission. In the related art, the backlight driving circuit generally includes a reference voltage generating unit and a driving voltage generating unit. The reference voltage generating unit is used for generating a reference voltage according to the pulse width modulation signal, and the driving voltage generating unit is used for generating a driving voltage for driving the LED to emit light according to the reference voltage.
However, when the frequency of the pwm signal changes, the reference voltage generating unit may generate an incorrect reference voltage due to the incorrect acquisition of the frequency of the pwm signal, which may eventually cause the backlight module to flash.
It is to be noted that the information invented in the above background section is only for enhancing the understanding of the background of the present invention, and therefore, may include information that does not constitute prior art known to those of ordinary skill in the art.
Disclosure of Invention
The invention aims to provide a backlight driving circuit, a driving method, a backlight module and a display module. The backlight driving circuit provided by the disclosure can solve the problem that in the related art, when the frequency of a pulse width modulation signal changes, a backlight module flickers.
Additional features and advantages of the invention will be set forth in the detailed description which follows, or may be learned by practice of the invention.
According to an aspect of the present invention, there is provided a backlight driving circuit including a reference voltage generating unit configured to generate a reference voltage according to a pulse width modulation signal, a driving voltage generating unit configured to generate a driving voltage for driving a backlight to emit light according to the reference voltage, the backlight driving circuit further including: the device comprises a sampling hold circuit, a voltage detection unit, a counter and a processing unit. The input end of the sampling hold circuit is connected with the reference voltage generating unit, and the output end of the sampling hold circuit is connected with the driving voltage generating unit; the voltage detection unit is connected with the reference voltage generation unit and is used for detecting the change state of the reference voltage in real time and outputting an effective level signal when the reference voltage changes; the counter is connected with the voltage detection unit and is used for collecting the triggering times of the effective level signal; the processing unit is connected with the counter and the control end of the sampling and holding circuit and is used for outputting a control signal to the control end of the sampling and holding circuit according to the triggering times of the effective level signal acquired by the counter; when the number of times of triggering the effective level signal is less than three times, the control signal is a hold signal, and when the number of times of triggering the effective level signal is equal to three times, the control signal is a sampling signal.
In one exemplary embodiment of the present invention, the sample-and-hold circuit includes: the buffer circuit comprises a first buffer amplifier, a switch element, a second buffer amplifier and a storage capacitor. The positive input end of the first buffer amplifier forms the input end of the sample-hold circuit, the negative input end of the first buffer amplifier is connected with the output end, the first end of the switch element is connected with the output end of the first buffer amplifier, and the control end of the switch element forms the control end of the sample-hold circuit; the positive input end of the second cache amplifier is connected with the second end of the switch element, the negative input end of the second cache amplifier is connected with the output end, and the output end of the second cache amplifier forms the output end of the sample-hold circuit; the storage capacitor is connected between the second end of the switch element and the ground terminal.
In an exemplary embodiment of the present invention, the switching element is an N-type switching transistor or a P-type switching transistor.
In one exemplary embodiment of the present invention, the reference voltage generating unit includes: digital signal processing unit, analog signal generating unit. The digital signal processing unit is used for receiving the pulse width modulation signal and acquiring the duty ratio and the frequency of the pulse width modulation signal according to the pulse width modulation signal; the analog signal generating unit is used for generating the reference voltage according to the duty ratio and the frequency of the pulse width modulation signal.
According to an aspect of the present invention, there is provided a driving method of a backlight driving circuit, applied to the backlight driving circuit, the driving method of the backlight driving circuit including:
detecting the change state of the reference voltage in real time by using a voltage detection unit, and outputting an effective level signal when the reference voltage changes;
acquiring the triggering times of the effective level signal by using a counter;
outputting a control signal to a control end of the sampling hold circuit by using a processing unit according to the triggering times of the effective level signal acquired by the counter;
when the number of triggering times of the effective level signal is less than three times, the control signal is a holding signal, and when the number of triggering times of the effective level signal is equal to three times, the control signal is a sampling signal;
and controlling the voltage of the output end of the sampling and holding circuit according to the control signal.
In one exemplary embodiment of the present invention, the sample-and-hold circuit includes: the buffer circuit comprises a first buffer amplifier, a switch element, a second buffer amplifier and a storage capacitor. The positive input end of the first buffer amplifier forms the input end of the sample-hold circuit, the negative input end of the first buffer amplifier is connected with the output end, the first end of the switch element is connected with the output end of the first buffer amplifier, and the control end of the switch element forms the control end of the sample-hold circuit; the positive input end of the second cache amplifier is connected with the second end of the switch element, the negative input end of the second cache amplifier is connected with the output end, and the output end of the second cache amplifier forms the output end of the sample-hold circuit; the storage capacitor is connected between the second end of the switch element and the ground terminal.
In an exemplary embodiment of the present invention, the switching element is an N-type switching transistor or a P-type switching transistor.
In one exemplary embodiment of the present invention, the reference voltage generating unit includes: digital signal processing unit, analog signal generating unit. The digital signal processing unit is used for receiving the pulse width modulation signal and acquiring the duty ratio and the frequency of the pulse width modulation signal according to the pulse width modulation signal; the analog signal generating unit is used for generating the reference voltage according to the duty ratio and the frequency of the pulse width modulation signal.
According to an aspect of the present invention, a backlight module is provided, which includes the backlight driving circuit.
According to an aspect of the present invention, a display module is provided, which includes the backlight module.
The disclosure provides a backlight driving circuit, a driving method, a backlight module and a display module. The backlight driving circuit comprises a reference voltage generating unit and a driving voltage generating unit, wherein the reference voltage generating unit is used for generating a reference voltage according to a pulse width modulation signal, the driving voltage generating unit is used for generating a driving voltage for driving a backlight source to emit light according to the reference voltage, and the backlight driving circuit further comprises: the device comprises a sampling hold circuit, a voltage detection unit, a counter and a processing unit. The input end of the sampling hold circuit is connected with the reference voltage generating unit, and the output end of the sampling hold circuit is connected with the driving voltage generating unit; the voltage detection unit is connected with the reference voltage generation unit and is used for detecting the change state of the reference voltage in real time and outputting an effective level signal when the reference voltage changes; the counter is connected with the voltage detection unit and is used for collecting the triggering times of the effective level signal; the processing unit is connected with the counter and the control end of the sampling and holding circuit and is used for outputting a control signal to the control end of the sampling and holding circuit according to the triggering times of the effective level signal acquired by the counter; when the number of times of triggering the effective level signal is less than three times, the control signal is a hold signal, and when the number of times of triggering the effective level signal is equal to three times, the control signal is a sampling signal. In the backlight driving circuit provided by the disclosure, when the change times of the reference voltage collected by the counter is less than three times, the reference voltage generating unit outputs an error reference voltage, and the sample-and-hold circuit outputs the reference voltage output by the reference voltage generating unit in the previous period; when the change times of the reference voltage collected by the counter is equal to three times, the reference voltage generating unit outputs correct reference voltage, and the sampling holding circuit outputs the reference voltage generated by the reference voltage generating unit. On one hand, the backlight driving circuit provided by the disclosure can avoid the screen flashing phenomenon of the backlight module when the frequency of the pulse width modulation signal changes; on the other hand, the backlight driving circuit provided by the disclosure has a simple structure and lower cost.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a schematic diagram of a backlight driving circuit in the related art;
FIG. 2 is a timing diagram of the variation of the current of the light emitting device in the backlight driving circuit with the frequency of the PWM signal in the related art;
FIG. 3 is a schematic diagram of an exemplary embodiment of a backlight driving circuit according to the present disclosure;
FIG. 4 is a schematic diagram of a sample-and-hold circuit in an exemplary embodiment of a backlight driver circuit according to the disclosure;
FIG. 5 is a schematic diagram of another exemplary embodiment of a backlight driving circuit according to the present disclosure;
fig. 6 is a flowchart of an exemplary embodiment of a driving method of a backlight driving circuit according to the disclosure.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted.
Although relative terms, such as "upper" and "lower," may be used in this specification to describe one element of an icon relative to another, these terms are used in this specification for convenience only, e.g., in accordance with the orientation of the examples described in the figures. It will be appreciated that if the device of the icon were turned upside down, the element described as "upper" would become the element "lower". Other relative terms, such as "high," "low," "top," "bottom," "left," "right," and the like are also intended to have similar meanings. When a structure is "on" another structure, it may mean that the structure is integrally formed with the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via another structure.
The terms "a," "an," "the," and the like are used to denote the presence of one or more elements/components/parts; the terms "comprising" and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.
Fig. 1 is a schematic diagram of a backlight driving circuit in the related art. The backlight driving circuit includes a reference voltage generating unit 1 and a driving voltage generating unit 2. The reference voltage generating unit 1 is configured to generate a reference voltage Vref according to the pulse width modulation signal PWM, and the driving voltage generating unit 2 is configured to generate driving voltages CH1, CH2 … CH6 for driving the LEDs to emit light according to the reference voltage Vref. The driving voltages CH1 and CH2 … CH6 are in direct proportion to the reference voltage Vref, and accordingly, the driving currents generated by the driving voltages CH1 and CH2 … CH6 are also in direct proportion to the reference voltage Vref. The reference voltage generating unit 1 may include a digital signal processing unit 11 and an analog signal generating unit 12. The digital signal processing unit 11 is configured to receive the pulse width modulation signal, and obtain a duty ratio and a frequency of the pulse width modulation signal according to the pulse width modulation signal; the analog signal generating unit 12 is configured to generate the reference voltage Vref according to the duty ratio and the frequency of the pulse width modulation signal.
However, when the frequency of the PWM signal PWM changes, the reference voltage generating unit 1 may generate an erroneous reference voltage Vref due to the erroneous acquisition of the frequency of the PWM signal, which finally causes the phenomenon of screen flashing of the backlight module.
Fig. 2 is a timing chart showing the variation of the current of the light emitting element in the backlight driving circuit according to the frequency of the pwm signal in the related art. The backlight driving circuit generates the driving current according to the PWM signal in such a manner that the backlight driving circuit collects the time between two adjacent rising edges of the PWM signal as the period of the PWM signal, and at the same time, the backlight driving circuit collects the duty ratio of the PWM signal and converts the duty ratio into the driving current ILED after detecting 2 periods, as shown in fig. 2, when the frequency of the PWM signal changes from 1KHz to 200Hz, the driving current ILED changes. The backlight driving circuit recognizes the last rising edge of the pulse width modulation signal of 1Khz to the first rising edge of the pulse width modulation signal of 200Hz as one cycle at the time period t 1. The backlight driving circuit recognizes that the duty ratio of the pulse width modulation signal is 100% in the time period t2, and after two above periods (i.e. the end of the time period t 3), the backlight driving circuit updates the driving current to the maximum current. Similarly, in the time periods t4 and t5, the duty ratio of the pulse width modulation signal is identified as 100% by the backlight driving circuit; in the time periods t6 and t7, the drive current updated by the backlight drive circuit is the maximum current. During the time period t6, the backlight driving circuit recognizes the duty ratio of the pulse width modulation signal as 0%. After the time period t7, the backlight driving circuit updates the driving current to 0. Until the time T8, when the second rising edge of the 200Hz PWM signal occurs, the backlight driving circuit recognizes the correct PWM signal period and updates the driving current to the correct current two times later at the time T9. Therefore, when the frequency of the pwm signal changes, the driving current generated by the backlight driving circuit will increase, decrease, and finally become a normal value. Accordingly, the above-described variation process of the reference voltage Vref also exists. In the process of the current change, the backlight module can generate a screen flashing phenomenon.
Based on this, the present exemplary embodiment provides a backlight driving circuit, as shown in fig. 3, which is a schematic structural diagram of an exemplary embodiment of the backlight driving circuit of the present disclosure. The backlight driving circuit comprises a reference voltage generating unit 3 and a driving voltage generating unit 4, wherein the reference voltage generating unit 3 is used for generating a reference voltage according to a pulse width modulation signal, the driving voltage generating unit 4 is used for generating a driving voltage for driving the backlight source to emit light according to the reference voltage, and the backlight driving circuit further comprises: a sample-and-hold circuit 5, a voltage detection unit 6, a counter 7, and a processing unit 8. The input end of the sampling hold circuit 5 is connected with the reference voltage generating unit 3, and the output end is connected with the driving voltage generating unit 4; the voltage detection unit 6 is connected with the reference voltage generation unit 3, and is used for detecting the change state of the reference voltage in real time and outputting an effective level signal when the reference voltage changes; the counter 7 is connected with the voltage detection unit 6 and is used for collecting the triggering times of the effective level signal; the processing unit 8 is connected to the counter 7 and the control end of the sample-and-hold circuit 5, and is configured to output a control signal to the control end of the sample-and-hold circuit according to the number of trigger times of the effective level signal acquired by the counter; when the number of times of triggering the effective level signal is less than three times, the control signal is a hold signal, and when the number of times of triggering the effective level signal is equal to three times, the control signal is a sampling signal.
The present disclosure provides a backlight driving circuit. The backlight driving circuit comprises a reference voltage generating unit and a driving voltage generating unit, wherein the reference voltage generating unit is used for generating a reference voltage according to a pulse width modulation signal, the driving voltage generating unit is used for generating a driving voltage for driving a backlight source to emit light according to the reference voltage, and the backlight driving circuit further comprises: the device comprises a sampling hold circuit, a voltage detection unit, a counter and a processing unit. The input end of the sampling hold circuit is connected with the reference voltage generating unit, and the output end of the sampling hold circuit is connected with the driving voltage generating unit; the voltage detection unit is connected with the reference voltage generation unit and is used for detecting the change state of the reference voltage in real time and outputting an effective level signal when the reference voltage changes; the counter is connected with the voltage detection unit and is used for collecting the triggering times of the effective level signal; the processing unit is connected with the counter and the control end of the sampling and holding circuit and is used for outputting a control signal to the control end of the sampling and holding circuit according to the triggering times of the effective level signal acquired by the counter; when the number of times of triggering the effective level signal is less than three times, the control signal is a hold signal, and when the number of times of triggering the effective level signal is equal to three times, the control signal is a sampling signal. In the backlight driving circuit provided by the disclosure, when the change times of the reference voltage collected by the counter is less than three times, the reference voltage is located in the change period, the reference voltage generating unit outputs an error reference voltage, and the sampling and holding circuit outputs the reference voltage output by the reference voltage generating unit under the action of the holding signal; when the change times of the reference voltage collected by the counter is equal to three times, the reference voltage generating unit outputs correct reference voltage, and the sampling holding circuit outputs the reference voltage generated by the reference voltage generating unit under the action of the adopted signal. On one hand, the backlight driving circuit provided by the disclosure can avoid the screen flashing phenomenon of the backlight module when the frequency of the pulse width modulation signal changes; on the other hand, the sampling hold circuit provided by the disclosure has the advantages of simple structure and lower cost.
In the present exemplary embodiment, as shown in fig. 4, a schematic diagram of a structure of a sample-and-hold circuit in an exemplary embodiment of the backlight driving circuit of the present disclosure is shown. The sample-and-hold circuit may include: a first buffer amplifier A1, a switch element T, a second buffer amplifier A2, and a storage capacitor C. The non-inverting INPUT end of the first buffer amplifier A1 forms the INPUT end INPUT of the sample-and-hold circuit, the inverting INPUT end is connected with the output end, the first end of the switch element T is connected with the output end of the first buffer amplifier A1, and the control end forms the control end SCN of the sample-and-hold circuit; the non-inverting input end of the second buffer amplifier a2 is connected to the second end of the switch element T, the inverting input end is connected to the output end, and the output end forms the output end of the sample-and-hold circuit; the storage capacitor C is connected between the second end of the switch element and the ground GND. When the control terminal SCN of the sample-and-hold circuit receives the sampling signal, the switching element T is turned on, and the voltage of the OUTPUT terminal OUTPUT of the sample-and-hold circuit is the voltage of the INPUT terminal INPUT. When the control terminal SCN of the sample-and-hold circuit receives the hold signal, the switching element T is turned off, and the voltage at the OUTPUT terminal OUTPUT of the sample-and-hold circuit is the voltage previously stored at the capacitor C at the INPUT terminal INPUT. Wherein the switching element is an N-type switching transistor or a P-type switching transistor. It should be understood that in other exemplary embodiments, the sample-and-hold circuit may have more alternative structures, which are within the scope of the present disclosure.
In the present exemplary embodiment, as shown in fig. 5, a schematic structural diagram of another exemplary embodiment of the backlight driving circuit of the present disclosure is shown. The reference voltage generating unit 3 may include: a digital signal processing unit 31 and an analog signal generating unit 32. The digital signal processing unit is used for receiving the pulse width modulation signal and acquiring the duty ratio and the frequency of the pulse width modulation signal according to the pulse width modulation signal; the analog signal generating unit is used for generating the reference voltage according to the duty ratio and the frequency of the pulse width modulation signal.
The present exemplary embodiment further provides a driving method of a backlight driving circuit, which is applied to the backlight driving circuit described above, and fig. 6 is a flowchart of an exemplary embodiment of the driving method of the backlight driving circuit according to the present disclosure. The backlight driving circuit driving method comprises the following steps:
step S1: detecting the change state of the reference voltage in real time by using a voltage detection unit, and outputting an effective level signal when the reference voltage changes;
step S2: acquiring the triggering times of the effective level signal by using a counter;
step S3: outputting a control signal to a control end of the sampling hold circuit by using a processing unit according to the triggering times of the effective level signal;
when the number of triggering times of the effective level signal is less than three times, the control signal is a holding signal, and when the number of triggering times of the effective level signal is equal to three times, the control signal is a sampling signal;
step S4: and controlling the voltage of the output end of the sampling and holding circuit according to the control signal.
In the present exemplary embodiment, the sample-and-hold circuit includes: the buffer circuit comprises a first buffer amplifier, a switch element, a second buffer amplifier and a storage capacitor. The positive input end of the first buffer amplifier forms the input end of the sample-hold circuit, the negative input end of the first buffer amplifier is connected with the output end, the first end of the switch element is connected with the output end of the first buffer amplifier, and the control end of the switch element forms the control end of the sample-hold circuit; the positive input end of the second cache amplifier is connected with the second end of the switch element, the negative input end of the second cache amplifier is connected with the output end, and the output end of the second cache amplifier forms the output end of the sample-hold circuit; the storage capacitor is connected between the second end of the switch element and the ground terminal.
In the present exemplary embodiment, the switching element is an N-type switching transistor or a P-type switching transistor.
In the present exemplary embodiment, the reference voltage generating unit includes: digital signal processing unit, analog signal generating unit. The digital signal processing unit is used for receiving the pulse width modulation signal and acquiring the duty ratio and the frequency of the pulse width modulation signal according to the pulse width modulation signal; the analog signal generating unit is used for generating the reference voltage according to the duty ratio and the frequency of the pulse width modulation signal.
The driving method of the backlight driving circuit provided by the present disclosure has the same technical features and working principles as the backlight driving circuit, and the above contents have been described in detail and are not repeated herein.
The exemplary embodiment further provides a backlight module, which includes the backlight driving circuit.
The backlight module provided by the present disclosure has the same technical features and working principles as the backlight driving circuit, and the above contents have been described in detail and are not repeated herein.
The exemplary embodiment provides a display module, which includes the backlight module.
The display module provided by the present disclosure has the same technical features and working principles as the backlight module, and the above contents have been described in detail and are not repeated herein.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is to be limited only by the terms of the appended claims.
Claims (10)
1. A backlight driving circuit comprises a reference voltage generating unit and a driving voltage generating unit, wherein the reference voltage generating unit is used for generating a reference voltage according to a pulse width modulation signal, and the driving voltage generating unit is used for generating a driving voltage for driving a backlight source to emit light according to the reference voltage, and the backlight driving circuit further comprises:
the input end of the sampling hold circuit is connected with the reference voltage generating unit, and the output end of the sampling hold circuit is connected with the driving voltage generating unit;
the voltage detection unit is connected with the reference voltage generation unit and is used for detecting the change state of the reference voltage in real time and outputting an effective level signal when the reference voltage changes;
the counter is connected with the voltage detection unit and is used for collecting the triggering times of the effective level signal;
the processing unit is connected with the counter and the control end of the sampling and holding circuit and used for outputting a control signal to the control end of the sampling and holding circuit according to the triggering times of the effective level signal acquired by the counter;
when the number of times of triggering the effective level signal is less than three times, the control signal is a holding signal, and the sampling holding circuit outputs the reference voltage output by the reference voltage generating unit under the action of the holding signal;
when the number of times of triggering the effective level signal is equal to three times, the control signal is a sampling signal, and the sampling holding circuit outputs the reference voltage generated by the reference voltage generating unit under the action of the sampling signal.
2. The backlight driving circuit according to claim 1, wherein the sample-and-hold circuit comprises:
a first buffer amplifier, wherein the positive input end forms the input end of the sample hold circuit, the negative input end is connected with the output end,
the first end of the switch element is connected with the output end of the first buffer amplifier, and the control end of the switch element forms the control end of the sample-hold circuit;
a second buffer amplifier, wherein the positive input end is connected with the second end of the switch element, the negative input end is connected with the output end, and the output end forms the output end of the sample hold circuit;
and the storage capacitor is connected between the second end of the switch element and the grounding end.
3. The backlight driving circuit according to claim 2, wherein the switching element is an N-type switching transistor or a P-type switching transistor.
4. The backlight driving circuit according to claim 1, wherein the reference voltage generating unit comprises:
the digital signal processing unit is used for receiving the pulse width modulation signal and acquiring the duty ratio and the frequency of the pulse width modulation signal according to the pulse width modulation signal;
and the analog signal generating unit is used for generating the reference voltage according to the duty ratio and the frequency of the pulse width modulation signal.
5. A backlight driving circuit driving method applied to the backlight driving circuit according to any one of claims 1 to 4, comprising:
detecting the change state of the reference voltage in real time by using a voltage detection unit, and outputting an effective level signal when the reference voltage changes;
acquiring the triggering times of the effective level signal by using a counter;
outputting a control signal to a control end of the sampling hold circuit by using a processing unit according to the triggering times of the effective level signal;
when the number of times of triggering the effective level signal is less than three times, the control signal is a holding signal, and the sampling holding circuit outputs the reference voltage output by the reference voltage generating unit under the action of the holding signal;
when the number of times of triggering the effective level signal is equal to three times, the control signal is a sampling signal, and the sampling holding circuit outputs a reference voltage generated by a reference voltage generating unit under the action of the sampling signal;
and controlling the voltage of the output end of the sampling and holding circuit according to the control signal.
6. The backlight driving circuit driving method according to claim 5, wherein the sample-and-hold circuit comprises:
a first buffer amplifier, wherein the positive input end forms the input end of the sample hold circuit, the negative input end is connected with the output end,
the first end of the switch element is connected with the output end of the first buffer amplifier, and the control end of the switch element forms the control end of the sample-hold circuit;
a second buffer amplifier, wherein the positive input end is connected with the second end of the switch element, the negative input end is connected with the output end, and the output end forms the output end of the sample hold circuit;
and the storage capacitor is connected between the second end of the switch element and the grounding end.
7. The backlight driving circuit driving method according to claim 6, wherein the switching element is an N-type switching transistor or a P-type switching transistor.
8. The backlight driving circuit driving method according to claim 5, wherein the reference voltage generating unit includes:
the digital signal processing unit is used for receiving the pulse width modulation signal and acquiring the duty ratio and the frequency of the pulse width modulation signal according to the pulse width modulation signal;
and the analog signal generating unit is used for generating the reference voltage according to the duty ratio and the frequency of the pulse width modulation signal.
9. A backlight module comprising the backlight driving circuit as claimed in any one of claims 1 to 4.
10. A display module comprising the backlight module of claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910453004.8A CN110010089B (en) | 2019-05-28 | 2019-05-28 | Backlight driving circuit and driving method, backlight module and display module |
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| CN201910453004.8A CN110010089B (en) | 2019-05-28 | 2019-05-28 | Backlight driving circuit and driving method, backlight module and display module |
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| CN111429852B (en) * | 2020-04-20 | 2022-04-26 | 昆山龙腾光电股份有限公司 | Control circuit and control method of liquid crystal display and display device |
| WO2023077410A1 (en) * | 2021-11-05 | 2023-05-11 | Boe Technology Group Co., Ltd. | Method and apparatus for generating driving signal, backlight, and display apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH04191886A (en) * | 1990-11-27 | 1992-07-10 | Toshiba Corp | Integrated-circuit for display driving |
| US20020063672A1 (en) * | 2000-11-29 | 2002-05-30 | Stevens Jessica L. | Method of gray scale generation for displays using a sample and hold circuit with discharge |
| JP4241487B2 (en) * | 2004-04-20 | 2009-03-18 | ソニー株式会社 | LED driving device, backlight light source device, and color liquid crystal display device |
| JP4306657B2 (en) * | 2004-10-14 | 2009-08-05 | ソニー株式会社 | Light emitting element driving device and display device |
| US7528555B2 (en) * | 2007-08-01 | 2009-05-05 | Micrel, Inc. | LED controller IC using only one pin to dim and set a maximum LED current |
| CN201623362U (en) * | 2010-03-29 | 2010-11-03 | 深圳新飞通光电子技术有限公司 | External burst automatic optical power control circuit |
| JP5523917B2 (en) * | 2010-04-23 | 2014-06-18 | ローム株式会社 | Switching power supply control circuit, control method, and light emitting device and electronic apparatus using them |
| US8384304B2 (en) * | 2010-08-23 | 2013-02-26 | Immense Advance Technology Corp. | LED driver controller |
| CN103177698B (en) * | 2013-03-27 | 2016-02-03 | 深圳市华星光电技术有限公司 | A kind of LED backlight drive circuit and backlight module |
| US9276477B2 (en) * | 2013-11-21 | 2016-03-01 | Stmicroelectronics International N.V. | DC-DC converter with enhanced automatic switching between CCM and DCM operating modes |
| CN107370375B (en) * | 2017-07-19 | 2019-08-23 | 深圳芯智汇科技有限公司 | DC-DC conversion circuit current sample, current-sharing control method and circuit |
| CN108848597B (en) * | 2018-08-22 | 2020-07-31 | 昂宝电子（上海）有限公司 | L ED lamp current control method and system |
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