CN101426312A - Backlight device - Google Patents
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- CN101426312A CN101426312A CNA2007101669179A CN200710166917A CN101426312A CN 101426312 A CN101426312 A CN 101426312A CN A2007101669179 A CNA2007101669179 A CN A2007101669179A CN 200710166917 A CN200710166917 A CN 200710166917A CN 101426312 A CN101426312 A CN 101426312A
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Abstract
The present invention relates to a backlight device which comprises a light emitting unit, a voltage converter, a voltage detecting unit, a correcting unit and a feedback control unit, wherein, the light emitting unit is provided with a first connecting end and a second connecting end. The voltage converter converts an input voltage to a rated voltage according to a periodic signal. The voltage detecting unit detects the voltage level between the first connecting end and the second connecting end to generate a measuring voltage. The correcting unit executes gain executes gain correction to the measuring voltage and adjusts the corrected voltage with a scaling for generating a correcting voltage. The feedback control unit outputs a feedback signal according to the correcting voltage. The voltage converter dynamically modifies the periodic signal according to the feedback signal.
Description
Technical Field
The present invention relates to a backlight device for a display, and more particularly, to a backlight device for dynamically modifying a voltage for driving light emitting diodes.
Background
For various types of display devices, liquid crystal displays are currently the mainstream products. Since the lcd has advantages of high image quality, low power consumption, thin mass production, low voltage driving, and small size, it has a lot of importance in the market, such as small portable tv, video phone, camcorder, notebook computer, desktop monitor, and lcd tv.
The liquid crystal display mainly comprises a liquid crystal display panel, a backlight module and a frame. The light source generated by the backlight module is an important factor for determining the chromaticity and brightness of the liquid crystal display. Fig. 1 is a schematic diagram of a conventional backlight device 100. Referring to fig. 1, a backlight device 100 includes a voltage converter 110 and light emitting units 120a to 120 n. Wherein,the light emitting units 120 a-120 n are all electrically connected to the voltage converter 110, and the light emitting unit 120a includes M light emitting diodes D11～DM1A switch SW1 and a constant current source CS1, M is an integer greater than 0. And so on the internal components of the light emitting units 120 b-120 n.
In order to easily illustrate the problems of the conventional backlight device 100, a partial structure diagram of the conventional backlight device 100 shown in fig. 2 will be described. Referring to fig. 2, the voltage converter 110 receives an input voltage V from its input terminalI1Then, the input voltage V is converted into a voltage according to the internal periodic signalI1Conversion to a rated voltage VO1And transmitted to the light emitting unit 120 a. When the switch SW1 of the light emitting unit 120a is turned on, the light emitting unit 120a passes the rated voltage VO1To drive the internal LED to emit light D11～DM1And the light emitting diode D is adjusted by the constant current source CS1 in the LED11～DM1The brightness of (2).
Since the voltage converter 110 determines the rated voltage V according to its internal periodic signalO1So that the rated voltage V is fixed when the periodic signal is fixedO1Will also be fixed therewith. However, the light emitting diode D11～DM1The forward voltage (forward voltage) of the LED decreases with the temperature of the system, i.e. the LED D11～DM1The voltage difference between both ends becomes small. Therefore, the excess voltage will be absorbed by the switch SW1 and the energy will be released in the form of heat by the switching of the switch SW1, resulting in increased temperature and wasted energy.
For example, referring to FIG. 2, LED D11Having a forward voltage V11Light emitting diode D21Having a forward voltage V12And so on for the rest. In addition, the voltage dropped on the switch SW1 is made to be the voltage VSW1And the voltage dropped on the constant current source CS1 is the voltage VC1Thus, the first formula V can be obtainedO1＝V11+...+V1M+VSAnd a second mathematical formula VS＝VSW1+VC1. First, from the first mathematical expression, when the light emitting diode D11～DM1Forward voltage V due to temperature rise11～V1MAt the time of falling, due to rated voltage VO1Is fixed, so that the voltage VSWill rise accordingly. From the second equation, the voltage V isC1Is fixed, so that the voltage VSThe rising part is completely absorbed by switch SW 1. As a result, a lot of energy is dissipated as heat (the energy loss of the switch is divided into conduction loss and switching loss), which causes the temperature of the system to rise and the excessive power consumption, and the operating efficiency of the system is reduced accordingly.
Disclosure of Invention
The invention provides a backlight device, which can solve the problem that the switch temperature rises due to the fact that the forward voltage of a light-emitting diode drops because of the temperature rise, and the redundant voltage is absorbed by a switch.
The invention provides a backlight device, which can improve the influence of the temperature rise of a light emitting diode, and can effectively prevent the redundant power consumption and the temperature rise of the device, so that the overall efficiency can be improved.
The invention provides a backlight device, which comprises a light emitting unit, a voltage converter, a voltage detection unit, a correction unit and a feedback control unit. The light-emitting unit is provided with a first connecting end and a second connecting end. The voltage converter converts an input voltage to a rated voltage according to a periodic signal, and the rated voltage drives the light emitting unit through a first connection terminal of the light emitting unit.
The voltage detection unit is used for detecting the voltage level on the first connecting end and the second connecting end of the light-emitting unit, so as to generate a measurement voltage. The calibration unit is used for performing gain calibration on the measurement voltage and adjusting the calibrated measurement voltage by using a scaling ratio so as to generate a calibration voltage. The feedback control unit outputs a feedback signal according to the correction voltage, and the voltage converter dynamically modifies the periodic signal according to the feedback signal.
From another perspective, the present invention provides a backlight device, which includes N light emitting units, a voltage converter, N voltage detecting units, a voltage comparing unit, a correcting unit, and a feedback control unit. Each unit of the N light-emitting units is provided with a first connecting end and a second connecting end, and N is an integer larger than 0. The voltage converter converts the input voltage to a rated voltage according to a periodic signal, and the rated voltage drives each light emitting unit through the first connection terminal of each light emitting unit.
Receiving the above, each of the N voltage detecting units generates a measurement voltage, and an ith voltage detecting unit of the N voltage detecting units is used to detect voltage levels at two connection terminals of an ith light emitting unit, so as to generate an ith measurement voltage, where i is an integer and 1 ≦ i ≦ N. The voltage comparison unit is used for comparing the measurement voltages generated by the N voltage detection units and selecting one of the measurement voltages as a maximum measurement voltage to output according to a comparison result.
On the other hand, the calibration unit is used for performing gain calibration on the measurement voltage and adjusting the calibrated measurement voltage by using a scaling ratio so as to generate a calibration voltage. The feedback control unit outputs a feedback signal according to the correction voltage, and the voltage converter dynamically modifies the periodic signal according to the feedback signal.
The invention adopts the design of the feedback circuit, so that the voltage converter can dynamically modify the internal periodic signal according to a feedback signal to change the output rated voltage, thereby effectively improving the defects of the prior art and preventing the temperature of the switch from rising. In addition, the rated voltage can be dynamically adjusted to prevent redundant power consumption and temperature rise of the device, so that the overall efficiency can be improved.
Drawings
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below, wherein:
fig. 1 is a schematic diagram of a conventional backlight device 100.
Fig. 2 is a partial structure diagram of the conventional backlight device 100.
Fig. 3A is a schematic diagram of a backlight device 300 according to an embodiment of the invention.
Fig. 3B is a schematic diagram of the backlight device 300 using another type of voltage detection unit.
Fig. 4A is a schematic diagram of a backlight device 400 according to another embodiment of the invention.
Fig. 4B is a schematic diagram of the backlight device 400 using another type of voltage detection unit.
Description of the main element symbols:
100. 300, 400: backlight device
110. 320, 460: voltage converter
120a to 120n, 310, 410a to 410 n: light emitting unit
330. 380, 420a to 420n, 480a to 480 n: voltage detection unit
340. 440, a step of: correction unit
350. 450: feedback control unit
311. 411 a: current generating unit
430: voltage comparison unit
D1～DM、D11～DM1: light emitting element
C1、C2、C11、C12: capacitor with a capacitor element
T1、T41: transformer device
E1～EN: diode with a high-voltage source
SW1, SW31, SW 41: switch with a switch body
CS1, CS31, CS 41: constant current source
S1、S11～SN1: first connecting end
S2、S12～SN2: second connecting end
V11、VI3、VI4: input voltage
VO1、VO3、VO4: rated voltage
V11～V1M、V31～V3M: forward voltage
VSW1、VC1、VSW3、VC3、VS: voltage of
VM31, V41a to V41 n: measuring voltage
VM32, V42: correcting voltage
S31, S41: feedback signal
VM 41: maximum measured voltage
Detailed Description
Fig. 3A is a schematic diagram of a backlight device 300 according to an embodiment of the invention. Referring to fig. 3, the backlight device 300 includes a light emitting unit 310, a voltage converter 320, a voltage detecting unit 330, a correcting unit 340, and a feedback control unit 350. Wherein the light emitting unit 310 has a firstConnecting end S1And a second connection terminal S2A first connection end S thereof1Electrically connected to the output terminal of the voltage converter 320, and the second connection terminal S thereof2Electrically connected to the voltage detecting unit 330.
To receive the above, the voltage detection unit 330 is electrically connected to the first connection end S1And a second connection terminal S2And is used for detecting the voltage level of the two connection terminals and generating a measurement voltage VM31 accordingly. The calibration unit 340 is electrically connected to the voltage detection unit 330 and the feedback control unit 350, and is configured to perform gain calibration on the measurement voltage VM31, and adjust the calibrated measurement voltage VM31 by a scaling factor, so as to generate a calibration voltage VM 32. The feedback control unit 350 is electrically connected to the voltage converter 320, and is configured to output a feedback signal S31 to the voltage converter 320 according to the calibration voltage VM 32.
The light emitting unit 310 includes a plurality of light emitting devices D1～DMAnd a current generating unit 311, M being an integer greater than 0. Wherein the light emitting element D1～DMAre connected in series with each other at the first connection end S of the light emitting unit 3101And a second connection terminal S2And a light emitting element D1～DMRespectively, a light emitting diode. Here, the light emitting element D1The first terminal (anode terminal) is electrically connected to the first connection terminal S1And a light emitting element DMThe second terminal (cathode terminal) is electrically connected to the second connection terminal S2。
Furthermore, the current generating unit 311 is electrically connected to the second connection terminal S of the light emitting unit 3102And ground, it includes a switch SW31 and a constant current source CS 31. One end of the switch SW31 is electrically connected to the second connection end S2The other end of the constant current source CS31 is electrically connected to the ground terminal, and the other end of the constant current source CS31 is electrically connected to the ground terminal. Here, the current generating unit 311 regulates and controls the current flowing through the light emitting device D according to a control signal1～DMThe current of (2). In other words, the switch SW31 determines its conducting state according to the control signal to control whether the current provided by the constant current source CS31 flows or notLight emitting element D1～DM。
The voltage detecting unit 330 includes a capacitor C1And C2. Wherein, the capacitor C1The first terminal is electrically connected to the first connection terminal S1A second terminal for outputting a measurement voltage VM31, and a capacitor C2The first end of the capacitor is electrically connected with the capacitor C1A second terminal of the first terminal is electrically connected to the second connection terminal S2。
Referring to fig. 3A, the voltage converter 320 receives an input voltage VI3Then, the input voltage V is converted into the output voltage V according to the internal periodic signalI3Enlargement or reduction, the purpose of which is to convert the input voltage VIConversion to a rated voltage VO3. When the switch SW31 is turned on according to the control signal, the light emitting unit 301 outputs the rated voltage V provided by the voltage converter 320O3To drive the light emitting element D therein1～DMAnd the light-emitting element D can be regulated and controlled by adjusting the constant current source CS311～DMThe brightness of (2).
Suppose a light emitting element D1Having a forward voltage V31Light-emitting element DMHaving a forward voltage V3MThe rest are analogized, and assume that the voltage at switch SW31 is voltage VSW3And the voltage at the constant current source CS31 is the voltage VC3. Since the light emitting element D1～DMThe forward voltage will decrease due to the temperature rise, so that the forward voltage V is equal tof1～VfMWhen the voltage drops, the voltage detection unit 330 will obtain the first connection terminal S1And a second connection terminal S2The variation of the intermediate voltage generates a measurement voltage VM31, which is sent to the calibration unit 340.
After receiving the measurement voltage VM31, the calibration unit 340 performs gain calibration on the measurement voltage VM31, and adjusts the calibrated measurement voltage VM31 by a scaling factor to generate a calibration voltage VM 32. That is, the first connection end S is obtained1And a second connection terminal S2After the voltage level therebetween, the correcting unit 3The voltage level obtained at this moment is subtracted from the voltage level obtained at the previous moment to obtain a voltage variation. Then, the correction unit 340 performs a nonlinear operation on the variation to generate a correction voltage VM32, and outputs the correction voltage VM32 to the feedback control unit 350.
After the feedback control unit 350 receives the calibration voltage VM32, a feedback signal S31 is generated according to the calibration voltage VM32 and transmitted to the voltage converter 320. That is, the feedback control unit 350 performs unit conversion on the received correction voltage VM32, thereby generating the feedback signal S31. After receiving the feedback signal S31, the voltage converter 320 modifies the internal periodic signal according to the feedback signal S31 to change the output rated voltage VO3. For example, the voltage converter 320 originally scales the input voltage V by a proportional value according to the internal periodic signalI3To generate a rated voltage VO3However, after receiving the feedback signal S31, the feedback signal S31 is added or subtracted with the periodic signal to generate a new periodic signal for correction to scale the input voltage VI3The proportional value of (c).
Here, the coupling manner of the voltage converter 320, the voltage detection unit 330, the correction unit 340 and the feedback control unit 350 can be regarded as a feedback circuit. By means of the feedback circuit, the backlight device 300 can adjust the rated voltage V at any timeO3The size of (2). Therefore, the voltage detection unit 330 only needs to obtain the light emitting element D1～DMThe forward voltage variation can immediately generate a feedback signal S31 to modify the periodic signal in the voltage converter 320, thereby changing the rated voltage VO3So as to cause a voltage drop across switch SW31SW3Not to rise. In addition, light emitting element D1～DMThe forward voltage drop due to the temperature rise is not linear, so the gain calibration performed by the calibration unit 340 on the measurement voltage VM31 is performed in a non-linear manner to meet the actual system requirements.
It is worth mentioning here that in the backlight device 300The architecture of the voltage detection unit 330 is not limited to the above. For example, fig. 3B shows an architecture diagram of the backlight device 300 using another type of voltage detection unit, wherein the voltage detection unit 380 is used to replace the voltage detection unit 330 in fig. 3A. Referring to fig. 3B, the voltage detection unit 380 includes a transformer T1. Wherein, the transformer T1Having a primary side and a secondary side, a first terminal of the primary side is electrically connected to the first connection terminal S of the light emitting unit 3101A second terminal of the primary side is electrically connected to the second connection terminal S of the light emitting unit 3102The first terminal of the secondary side is used for generating a measurement voltage VM31, and the second terminal of the secondary side is electrically connected to the ground terminal.
Receiving the above, using the above transformer T1In the coupling manner of (1), the voltage detection unit 380 can achieve the effect of the voltage detection unit 330 composed of a capacitor. Therefore, it should be understood by those skilled in the art that the voltage detection unit in the backlight device 300 is not limited to the above embodiments, and a user can also use an amplifier design circuit to achieve the effect of the voltage detection unit.
Fig. 4A is a schematic diagram of a backlight device 400 according to another embodiment of the invention. Referring to fig. 4A, the backlight device 400 includes N light emitting units 410a to 410N, a voltage converter 460, N voltage detecting units 420a to 420N, a voltage comparing unit 430, a correcting unit 440, and a feedback control unit 450, where N is an integer greater than 0. The light emitting units 410 a-410 n each have a first connection end and a second connection end, for example, the light emitting unit 410a has a first connection end S11And a second connection terminal S12The light emitting unit 410b has a first connection end SN1And a second connection terminal SN2And so on for the rest. First connection ends S of all light emitting units11～SN1The output terminals of the voltage converter 460 are electrically connected together, and the second connection terminal S is12～SN2Each of which is electrically connected to a corresponding voltage detection unit 420 a-420 n.
The voltage detection units 420 a-420 n are electrically connected to each otherIs connected with the corresponding first connecting end S11～SN1And a second connection terminal S12～SN2For example, the voltage detection unit 420a is electrically connected to the first connection terminal S11And a second connection terminal S12The voltage detecting unit 420n is electrically connected to the first connection end SN1And a second connection terminal SN2In the meantime. In addition, the voltage detection units 420 a-420 n are used for detecting the voltage levels of the two connection ends and respectively generating a measurement voltage. For example, the voltage detecting unit 420a is electrically connected to the first connection end S11And a second connection terminal S12And is used for detecting the voltage level of the two connection ends and generating a measuring voltage V41a according to the voltage level. The voltage comparing unit 430 is electrically connected to the voltage detecting units 420 a-420 n, and configured to compare the voltage values of the measured voltages V41 a-V41 n, and select one of the compared values as a maximum measured voltage VM 41.
The calibration unit 440 is electrically connected to the voltage comparison unit 430 and the feedback control unit 450, and the feedback control unit 450 is electrically connected to the voltage converter 460, which has the same function as the above embodiments, so the description thereof is omitted.
Referring to fig. 4A, the structure and the function of the backlight device 400 of the present embodiment are very similar to those of the above embodiments, except for the number of the voltage comparing unit, the light emitting unit and the voltage detecting unit. Therefore, the spirit of the present embodiment will now be described with respect to these units (410a to 410n, 420a to 420n, 430).
In the light emitting units 410 a-410 n, each unit includes M light emitting devices and a current generating unit, M is an integer greater than 0, for example, the light emitting unit 420a includes a light emitting device D11～DM1And the current generating unit 411a, and so on, the internal components of the light emitting units 410b to 410 n. Herein, the current generating unit 411a includes a switch SW41 and a constant current source CS41, which controls the current flowing through the light emitting device D according to a control signal11～DM1The current of (2). In other words, the switch SW41 is turned on according to the control signal to control the constant current source CS41Whether or not a current flows through the light emitting element D11～DM1。
In the voltage detection units 420 a-420 n, each unit includes two capacitors, and the two capacitors are connected in series and electrically connected between the corresponding first connection end and the second connection end. For example, the voltage detection unit 420a includes a capacitor C11And C12Wherein the capacitance C11The first terminal is electrically connected to the first connection terminal S11The second terminal is electrically connected to the capacitor C12A first terminal of, and a capacitor C12The second terminal of the first terminal is electrically connected to the second connection terminal S12And the first terminal is used to generate a measurement voltage V41 a. By analogy, the internal components of the voltage detection units 420 b-420 n are coupled thereto.
The voltage comparison unit 430 includes N diodes E1～ENWherein the anode terminal of each diode is electrically connected to the corresponding voltage detection unit (e.g. diode E)1Is electrically connected to the voltage detection unit 420a), and the diode E1～ENThe cathode terminals are electrically connected to the calibration unit 440.
In fig. 4A, the forward voltages of the light emitting units 420a to 420N may decrease due to the temperature rise, and each of the voltage detecting units obtains a corresponding measuring voltage, so that N measuring voltages V41a to V41N are obtained for N voltage detecting units 420a to 420N. Therefore, the voltage comparing unit 430 receives the measurement voltages V41 a-V41 n and compares the voltage values of the measurement voltages V41 a-V41 n, and then selects one of the measurement voltages V41 a-V41 n as a maximum measurement voltage VM41 according to the comparison result. For example, if the voltage comparing unit 430 includes only the diode E1And E2And a diode E1Receiving a measuring voltage V41a of 2 volts, and a diode E2When receiving the measuring voltage V41b of 1 volt, the diode E1Will get a voltage of 2 volts, so that the diode E2The received 1 volt cannot pass through, so the maximum measurement voltage generated by this principle is 2 volts.
After the maximum measurement voltage VM41 is obtained, the following operations are similar to the above embodiment. The calibration unit 440 performs gain calibration and scaling on the maximum measurement voltage VM41 to generate a calibration voltage V42 to be transmitted to the feedback control unit 450, and the feedback control unit 450 generates a feedback signal S41 according to the calibration voltage V42 to modify the periodic signal of the voltage converter 460, thereby changing the nominal voltage VO4。
It should be noted that the structure of the voltage detecting units 420 a-420 n in the backlight device 400 is not limited to the above. For example, FIG. 4B is an architecture diagram of the backlight device 400 using another type of voltage detecting units, wherein the voltage detecting units 480 a-480 n are used to replace the voltage detecting units 420 a-420 n in FIG. 4A. Referring to fig. 4B, each of the voltage detecting units 480a to 480n includes a transformer. Wherein, the transformer T41Having a primary side and a secondary side, wherein a first end and a second end of the primary side are electrically connected to the first connection end S of the light emitting unit 410a respectively11And a second connection terminal S12And the first terminal of the secondary side is used for generating a measurement voltage V41a, and the second terminal of the secondary side is electrically connected to the ground terminal. By analogy, the internal components of the voltage detection units 480 b-480 n are coupled thereto.
Receiving the above, using the above transformer T41In the coupling manner, the voltage detection units 480a to 480n can achieve the effect of the voltage detection units 420a to 420n formed by capacitors. Therefore, it should be understood by those skilled in the art that the voltage detecting unit in the backlight device 400 is not limited to the above embodiments.
In summary, the present invention employs a feedback circuit design, so that the voltage converter can modify its internal periodic signal according to a feedback signal, thereby changing its output rated voltage and preventing the switching temperature from rising, thereby preventing the excessive power consumption and the device temperature from rising, and making the state of the light emitting device more stable, so as to improve the overall efficiency of the system. In addition, the invention can be applied to any voltage converter architecture, so that the invention can be widely applied to improve the competitiveness of products.
Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (13)
1. A backlight device, comprising:
a light emitting unit having a first connection end and a second connection end;
the voltage converter is used for converting an input voltage to a rated voltage according to a periodic signal, and the rated voltage drives the light-emitting unit to emit light through the first connecting end of the light-emitting unit;
a voltage detection unit for detecting voltage levels on the first connection end and the second connection end of the light-emitting unit so as to generate a measurement voltage;
a calibration unit for performing gain calibration on the measurement voltage and adjusting the calibrated measurement voltage by a scaling ratio to generate a calibration voltage; and
and a feedback control unit for outputting a feedback signal according to the correction voltage, wherein the voltage converter dynamically modifies the periodic signal according to the feedback signal.
2. The backlight device of claim 1, wherein the voltage detection unit comprises:
a first capacitor, the first end of which is electrically connected to the first connection end of the light-emitting unit, and the second end of which is used for generating the measurement voltage; and
and a second capacitor, wherein a first end of the second capacitor is electrically connected to a second end of the first capacitor, and a second end of the second capacitor is electrically connected to the second connection end of the light-emitting unit.
3. The backlight device of claim 1, wherein the voltage detection unit comprises:
the transformer is provided with a primary side and a secondary side, a first end of the primary side is electrically connected to the first connecting end of the light-emitting unit, a second end of the primary side is electrically connected to the second connecting end of the light-emitting unit, the first end of the secondary side is used for generating the measuring voltage, and a second end of the secondary side is electrically connected to a grounding end.
4. The backlight device according to claim 1, wherein the light emitting unit comprises:
a plurality of light emitting elements connected in series between the first connection end and the second connection end of the light emitting unit; and
and the current generating unit is electrically connected between the second connecting end of the light-emitting unit and a grounding end and used for regulating and controlling the current flowing through the light-emitting elements according to a control signal.
5. The backlight device of claim 4, wherein the current generating unit comprises:
a switch, the first end of which is electrically connected to the second connecting end of the light-emitting unit, and the switch determines the conducting state according to the control signal; and
and the constant current source is electrically connected between the second end of the switch and the grounding end.
6. The backlight device of claim 4, wherein the light emitting elements are light emitting diodes.
7. A backlight device, comprising:
each light-emitting unit is provided with a first connecting end and a second connecting end, and N is an integer greater than 0;
the voltage converter is used for converting an input voltage to a rated voltage according to a period signal, and the rated voltage drives the light-emitting units to emit light through the first connecting end of each light-emitting unit;
n voltage detecting units for generating N measurement voltages, wherein an ith voltage detecting unit is configured to detect voltage levels at two connection terminals of an ith light emitting unit and generate an ith measurement voltage accordingly, wherein i is an integer and 1 ≦ i ≦ N;
a voltage comparison unit for comparing the voltage values of the measured voltages and selecting one of the measured voltages to output as a maximum measured voltage according to the comparison result;
a calibration unit for performing gain calibration on the maximum measurement voltage and adjusting the calibrated maximum measurement voltage by a scaling ratio to generate a calibration voltage; and
and a feedback control unit for outputting a feedback signal according to the correction voltage, wherein the voltage converter dynamically modifies the periodic signal according to the feedback signal.
8. The backlight device of claim 7, wherein the voltage comparing unit comprises:
and the anode of the ith diode is electrically connected to the ith voltage detection unit, and the cathode of each diode is electrically connected to the correction unit.
9. The backlight device as claimed in claim 7, wherein the ith voltage detecting unit comprises:
a first capacitor, wherein a first end of the first capacitor is electrically connected to the first connection end of the ith light emitting unit, and a second end of the first capacitor is used for generating the ith measurement voltage; and
and a second capacitor, wherein a first end of the second capacitor is electrically connected to a second end of the first capacitor, and a second end of the second capacitor is electrically connected to the second connection end of the ith light-emitting unit.
10. The backlight device as claimed in claim 7, wherein the ith voltage detecting unit comprises:
the transformer is provided with a primary side and a secondary side, a first end of the primary side is electrically connected to the first connecting end of the ith light-emitting unit, a second end of the primary side is electrically connected to the second connecting end of the ith light-emitting unit, the first end of the secondary side is used for generating the ith measuring voltage, and a second end of the secondary side is electrically connected to a grounding end.
11. The backlight apparatus of claim 7, wherein the ith light emitting unit comprises:
a plurality of light emitting elements connected in series between the first connection end and the second connection end of the ith light emitting unit; and
and the current generating unit is electrically connected between the second connecting end of the ith light-emitting unit and a grounding end and used for regulating and controlling the current flowing through the light-emitting elements according to a control signal.
12. The backlight device of claim 11, wherein the current generating unit comprises:
a switch, the first end of which is electrically connected to the second connecting end of the ith light-emitting unit, and the switch determines the conducting state according to the control signal; and
and the constant current source is electrically connected between the second end of the switch and the grounding end.
13. The backlight device of claim 11, wherein the light emitting elements are light emitting diodes.
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| CNA2007101669179A CN101426312A (en) | 2007-10-29 | 2007-10-29 | Backlight device |
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|---|---|---|---|
| CNA2007101669179A CN101426312A (en) | 2007-10-29 | 2007-10-29 | Backlight device |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101998725A (en) * | 2009-08-24 | 2011-03-30 | 华映视讯（吴江）有限公司 | Drive circuit of light-emitting diode |
| CN102800335A (en) * | 2011-05-25 | 2012-11-28 | 广明光电股份有限公司 | Compact disk drive focusing voltage correction method |
| CN101895194B (en) * | 2009-05-21 | 2012-11-28 | 华映视讯（吴江）有限公司 | Voltage converter, backlight module control system and control method thereof |
| CN103606354A (en) * | 2013-11-25 | 2014-02-26 | 深圳市华星光电技术有限公司 | LED backlight driving circuit and liquid crystal display |
| CN106163027A (en) * | 2015-03-26 | 2016-11-23 | 苏州璨宇光学有限公司 | Light source drive device and light source driving method |
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| CN103606354A (en) * | 2013-11-25 | 2014-02-26 | 深圳市华星光电技术有限公司 | LED backlight driving circuit and liquid crystal display |
| US9232575B2 (en) | 2013-11-25 | 2016-01-05 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | LCD backlight driving circuit and liquid crystal device |
| CN103606354B (en) * | 2013-11-25 | 2016-04-13 | 深圳市华星光电技术有限公司 | Led backlight drive circuit and liquid crystal display |
| CN106163027A (en) * | 2015-03-26 | 2016-11-23 | 苏州璨宇光学有限公司 | Light source drive device and light source driving method |
| CN106163027B (en) * | 2015-03-26 | 2018-12-04 | 苏州璨宇光学有限公司 | Light source drive device and light source driving method |
| CN106683622A (en) * | 2016-12-31 | 2017-05-17 | 深圳Tcl数字技术有限公司 | LOCAL DIMMING backlight drive circuit and electronic device |
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Application publication date: 20090506 |