WO2010150444A1 - 発光素子駆動装置、面状照明装置および液晶表示装置 - Google Patents
発光素子駆動装置、面状照明装置および液晶表示装置 Download PDFInfo
- Publication number
- WO2010150444A1 WO2010150444A1 PCT/JP2010/001748 JP2010001748W WO2010150444A1 WO 2010150444 A1 WO2010150444 A1 WO 2010150444A1 JP 2010001748 W JP2010001748 W JP 2010001748W WO 2010150444 A1 WO2010150444 A1 WO 2010150444A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- emitting element
- light emitting
- voltage
- voltage application
- unit
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/40—Details of LED load circuits
- H05B45/44—Details of LED load circuits with an active control inside an LED matrix
- H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
- H05B45/38—Switched mode power supply [SMPS] using boost topology
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Definitions
- the present invention relates to a light emitting element driving device for driving a light emitting element such as an LED (Light Emitting Diode) connected to a power supply circuit with a constant current, a planar illumination device including the light emitting element driving device, and the surface.
- the present invention relates to a liquid crystal display device using a planar illumination device as a backlight.
- the light-emitting element driving device disclosed in Patent Document 1 will be briefly described below with reference to FIG.
- the conventional light emitting element driving device includes a plurality of LED column loads each having one or more LEDs connected in series.
- Each LED string load 110 to 113 is driven by a constant current I0 to I3 generated by a constant current source 120 to 123 connected in series to each cathode terminal.
- Cathode terminal voltages V0 to V3 of the LED string loads 110 to 113 are input to the selection circuit 130.
- the selection circuit 130 selects the minimum voltage among the cathode terminal voltages V0 to V3 and outputs it as the detection voltage Vdet, and inputs the detection voltage Vdet to the control circuit 131.
- the control circuit 131 compares the detection voltage Vdet with an internal reference voltage Vref (not shown).
- the control circuit 131 inputs a switching signal Cont for operating the voltage conversion circuit 100 so that the detection voltage Vdet is equal to the reference voltage Vref to the gate of the transistor 103.
- the voltage conversion circuit 100 is a step-up conversion circuit including a coil 101, a diode 102, a transistor 103, and a capacitor 104, and a predetermined input voltage Vdd is changed to an output voltage Vh necessary for driving the LED string loads 110 to 113. Convert.
- the output voltage Vh is supplied to the anode terminals of the LED string loads 110 to 113.
- the amount of current flowing through the LED array loads 110 to 113 Can be adjusted. Thereby, it is possible to perform brightness
- the LED string load having the largest forward voltage drop among the LED string loads 110 to 113 that is, the LED string load having the smallest cathode terminal voltage among the cathode terminal voltages V0 to V3. Accordingly, the output voltage Vh of the voltage conversion circuit 100 is controlled. For this reason, it is possible to realize driving with less loss while ensuring sufficient light emission of the LED array loads 110 to 113.
- the case where the number of LED series connections per LED string load is four and the number of LED string loads connected in parallel is four.
- the scale of the LED array load increases, it is greatly affected by the variation of individual LEDs, so that the increase in power consumption becomes a more serious problem.
- an increase in power loss applied to the constant current source greatly affects the allowable loss of the package of the light emitting element driving device, which causes a problem that a package having a larger allowable loss is required.
- An object of the present invention is to provide a light emitting element driving device capable of suppressing an increase in power consumption caused by variations in forward voltage drop of LEDs, a planar lighting device using the same, and a liquid crystal display device. is there.
- the light emitting element driving device of the present invention generates an applied voltage based on a detection voltage determined based on the maximum forward voltage drop among the forward voltage drops of the plurality of light emitting element arrays. Switching between switching between a plurality of voltage applying sections that apply the generated applied voltage to the plurality of light emitting element arrays and a voltage applying section to which the plurality of light emitting element arrays are individually connected. And a control unit that controls the switching unit to switch the connection so that a difference in forward voltage drop between the plurality of light emitting element arrays is minimized.
- the planar illumination device of the present invention includes a plurality of light emitting element arrays arranged on a plane and the light emitting element driving device connected to the plurality of light emitting element arrays.
- the liquid crystal display device of the present invention is a liquid crystal display device that displays the image by inputting the planar illumination device and illumination light from the planar illumination device from the back, and spatially modulating the illumination light according to a video signal.
- a panel a liquid crystal display device that displays the image by inputting the planar illumination device and illumination light from the planar illumination device from the back, and spatially modulating the illumination light according to a video signal.
- the LED string load is classified based on the magnitude of the forward voltage drop of each LED string load, and the forward direction of the LED is controlled by recombination control to a plurality of voltage conversion circuits. It is possible to suppress an increase in power consumption caused by voltage variations.
- 1 is a block diagram showing an example of the overall configuration of a light emitting element driving apparatus according to Embodiment 1 of the present invention.
- the circuit diagram which shows the concrete structure of VF determination part 40 The flowchart which shows the operation
- the figure for demonstrating the state before LED row load recombination The figure for demonstrating the state after LED row load rearrangement
- the flowchart which shows the operation
- the block diagram which shows the example of whole structure of the light emitting element drive device which concerns on Embodiment 3 of this invention.
- FIG. 5 is a block diagram showing an example of the overall configuration of a light emitting element driving apparatus according to Embodiment 5 of the present invention. Transition diagram showing an operation sequence of the light emitting element driving apparatus according to Embodiment 5 of the present invention.
- 1 is a schematic configuration diagram of a liquid crystal display device including a planar illumination device according to an embodiment of the present invention.
- FIG. 3 is a block diagram illustrating an example of the overall configuration of the light emitting element driving apparatus according to Embodiment 1.
- the light emitting element driving apparatus includes voltage conversion circuits 1 and 2, switching circuits 30 to 31, constant current sources 21 to 24, minimum value detection units 32 and 34, and PWM control unit 33. , 35, a VF determination unit 40, a switching control unit 41, and a current control unit 42, and drives the LED string loads 11-14.
- the configuration including the voltage conversion circuit 1, the minimum value detection unit 32, and the PWM control unit 33 is a specific example of one voltage application unit. Further, the combined configuration of the switching circuits 30 and 31 is a specific example of the switching unit. Further, the configuration in which the VF determination unit 40, the switching control unit 41, and the current control unit 42 are combined is a specific example of the control unit.
- the LED array loads 11 to 14 are specific examples of the light emitting element arrays.
- the voltage application unit applies to the plurality of light emitting element rows connected based on a detection voltage determined based on the maximum forward voltage drop among the forward voltage drops of the plurality of light emitting element rows connected to each. Determine and apply voltage.
- the switching unit switches which voltage application unit of the plurality of voltage application units is connected to each of the light emitting element arrays.
- the control unit controls the switching unit so that the difference in forward voltage drop between the plurality of light emitting element arrays connected in each voltage application unit is minimized. Details will be described below using a specific configuration.
- the voltage conversion circuit 1 is a step-up switching power supply and includes a coil L1, a diode D1, a transistor M1, and a capacitor C1. Based on the control signal Vpwm1 from the PWM control unit 33, the voltage conversion circuit 1 boosts a predetermined input voltage Vcc to an output voltage Vout1 necessary for driving the LED string loads 11 to 14, and outputs an output voltage Vout1. To do.
- the voltage conversion circuit 2 is a step-up switching power supply, and includes a coil L2, a diode D2, a transistor M2, and a capacitor C2. Based on the control signal Vpwm2 from the PWM control unit 35, the voltage conversion circuit 2 boosts the predetermined input voltage Vcc to the output voltage Vout2 required for driving the LED string loads 11 to 14, and outputs the output voltage Vout2. To do.
- the switching circuit 30 is a selector circuit group having selectors 30a to 30d. Based on the control signal Vsel1 from the switching control unit 41, the switching circuit 30 converts the anode terminals P1H to P4H of the LED string loads 11 to 14 to the output terminal PO1 of the voltage conversion circuit 1 or the output of the voltage conversion circuit 2, respectively. Connect to one of the terminals PO2.
- the selectors 30a to 30d are configured by, for example, MOS switches.
- the constant current sources 21 to 24 are connected in series to the cathode terminals P1L to P4L of the LED string loads 11 to 14, respectively, and supply the constant currents I1 to I4 necessary for light emission of the LEDs to the LED string loads 11 to 14, respectively.
- Each of the constant current sources 21 to 24 can be turned on / off based on the control signal Vcnt from the current control unit 42, and adjusts the ratio between the on time and the off time. As a result, the amount of current supplied to each of the LED array loads 11 to 14 can be adjusted, and the light emission amount of the LED can be controlled.
- the switching circuit 31 is a selector circuit group having selectors 31a to 31d. Based on the control signal Vsel2 from the switching control unit 41, the switching circuit 31 converts the cathode terminal voltages Vfb1 to Vfb4 of the LED string loads 11 to 14 to either the minimum value detection unit 32 or the minimum value detection unit 34, respectively. Connect to.
- the selectors 31a to 31d are configured by, for example, MOS switches.
- the cathode terminal voltages Vfb1 to Vfb4 of the LED string loads 11 to 14 are determined based on the forward voltage drop of the LED string loads 11 to 14.
- the minimum value detection unit 32 selects the minimum voltage among the cathode terminal voltages connected by the switching circuit 31, and inputs the selected voltage to the PWM control unit 33 as the detection voltage Vdet1.
- the detection voltage Vdet1 does not need to be the same voltage as the selected minimum cathode terminal voltage.
- the detection voltage Vdet1 is generated based on the minimum voltage obtained by shifting the minimum voltage among the cathode terminal voltages by a predetermined voltage.
- the voltage may be
- the minimum value detection unit 34 selects the minimum voltage among the cathode terminal voltages connected by the switching circuit 31, and inputs the selected voltage to the PWM control unit 35 as the detection voltage Vdet2.
- the detection voltage Vdet2 does not need to be the same voltage as the selected minimum cathode terminal voltage.
- the detection voltage Vdet2 is generated based on the minimum voltage obtained by shifting the minimum voltage among the cathode terminal voltages by a predetermined voltage.
- the voltage may be
- Each of the minimum value detection units 32 and 34 is an example of a detection circuit.
- the PWM control unit 33 compares the input detection voltage Vdet1 with a reference signal Vref (not shown). Based on the comparison result, the control signal Vpwm1 is input to the gate of the transistor M1 of the voltage conversion circuit 1 so that the detection voltage Vdet1 becomes equal to the reference voltage Vref. Based on the control signal Vpwm1, the voltage conversion circuit 1 performs switching of the transistor M1 to generate an output voltage Vout1.
- the PWM control unit 35 compares the input detection voltage Vdet2 with a reference signal Vref (not shown). Based on the comparison result, the control signal Vpwm2 is input to the gate of the transistor M2 of the voltage conversion circuit 2 so that the detection voltage Vdet2 becomes equal to the reference voltage Vref. Based on the control signal Vpwm2, the voltage conversion circuit 2 performs switching of the transistor M2 to generate the output voltage Vout2.
- the VF determination unit 40 determines the magnitude relationship between the forward voltage drops in the LED string loads 11 to 14, and switches the determination signal Vch, which is the determination result, to the switching control unit 41. To enter.
- FIG. 4 is a diagram illustrating a specific configuration example of the VF determination unit 40.
- the cathode terminal voltages Vfb1 to Vfb4 of the constant current sources 21 to 24 are connected to the base terminals of the pnp transistors 51 to 54, respectively.
- the emitter terminals of the pnp transistors 51 to 54 are short-circuited at the contact E.
- a constant current source 50 for flowing a constant current Ib is connected between the power supply Vdd and the contact E.
- Resistors 55 to 58 are respectively connected between the collector terminals of the pnp transistors 51 to 54 and the ground, and the voltages of the collector terminals are set to predetermined logic level voltages Vch [0] to Vch via the buffer circuits 59 to 62, respectively. Converted to [3].
- the current Ib of the constant current source 50 flows through the pnp transistor connected to the minimum voltage among the cathode terminal voltages Vfb1 to Vfb4. Therefore, by monitoring each collector voltage, the minimum cathode terminal voltage among the cathode terminal voltages Vfb1 to Vfb4 can be specified.
- the obtained information is output to the switching control unit 41 as a 4-bit determination signal Vch [3: 0].
- the switching control unit 41 generates control signals Vsel1 to Vsel3 based on the input determination signal Vch, and inputs the control signals Vsel1 to Vsel3 to the switching circuits 30 and 31 and the current control unit 42, respectively.
- the switching control unit 41 is configured by a logic circuit or a microcomputer, for example.
- the current control unit 42 generates a control signal Vcnt for individually controlling on / off of the constant current sources 21 to 24 based on the control signal Vsel3, and inputs the control signal Vcnt to each of the constant current sources 21 to 24.
- LED row loads are grouped on the basis of variations in forward voltage drop between the respective LED row loads. Then, a plurality of LED string load groups obtained as a result of grouping are shared by a plurality of voltage conversion circuits. That is, a certain voltage conversion circuit drives an LED string load belonging to a certain LED string load group, and another voltage conversion circuit drives an LED string load belonging to another LED string load group. By performing such driving, the amount of variation in the forward voltage drop in the LED string load group connected to each voltage conversion circuit is reduced, and the power consumption is reduced.
- the control unit controls the switching unit so as to connect all the light emitting element rows to the same voltage applying unit, and then selects the maximum among the light emitting element rows connected to the voltage applying unit.
- the switching unit is controlled so that the light emitting element array having the forward voltage drop is connected to another voltage application unit.
- the relationship of the forward voltage drop of each of the LED string loads 11 to 14 is “Vf1 ⁇ Vf2 ⁇ Vf3 ⁇ Vf4”.
- the switching circuits 30 and 31 are controlled to connect the anode terminals P1H to P4H of all the LED string loads 11 to 14 to the output terminal PO2 of the voltage conversion circuit 2 and connect the cathode terminals P1L to P4L to the minimum value detection circuit 34. Connect to. That is, all the LED string loads 11 to 14 are connected to the system of the voltage conversion circuit 2 (voltage application unit having the voltage conversion circuit 2) (step S31). The equivalent circuit configuration at this time is as shown in FIG. Then, by turning on all the constant current sources 21 to 24, all the LED string loads 11 to 14 are driven (step S32).
- the VF determination unit 40 detects which cathode terminal voltage Vfb4 is the lowest among the cathode terminal voltages Vfb1 to Vfb4 applied to the constant current sources 21 to 24 that are turned on. It is determined whether driving is performed with the cathode terminal voltage (step S33). Then, the VF determination unit 40 notifies the determination result (determination signal Vch) to the switching control unit 41 (step S34).
- the switching control unit 41 inputs the control signal Vsel3 generated based on the determination result to the current control unit 42, and the current control unit 42 turns off the constant current source 24 to which the minimum cathode terminal voltage Vfb4 is applied (step S35). ).
- the switching control unit 41 controls the switching circuits 30 and 31 by the control signals Vsel1 and Vsel2 to switch the connection relating to the LED string load 14 having the minimum cathode terminal voltage Vfb4 (that is, the maximum forward voltage drop). (Step S36). Specifically, the switching control unit 41 switches the connection destination of the anode terminal P4H of the LED string load 14 from the output terminal PO2 of the voltage conversion circuit 2 to the output terminal PO1 of the voltage conversion circuit 1. In addition, the switching control unit 41 switches the connection destination of the cathode terminal P4L from the minimum value detection unit 34 to the minimum value detection unit 32.
- Steps S33 to S36 are repeated a number of times corresponding to 1/2 of the number of LED array loads (step S37).
- steps S33 to S36 are performed up to twice. Since steps S33 to S36 have been performed only once so far, they are performed only once. At this time, since the remaining constant current sources 21 to 23 other than the constant current source 24 are turned on, steps S33 to S36 are performed for the constant current sources 21 to 23.
- the VF determination unit 40 detects the minimum value of the cathode terminal voltages Vfb1 to Vfb3 applied to each constant current source to determine the constant current source to which the minimum cathode terminal voltage is applied, and the determination result (determination signal) Vch) is notified to the switching control unit 41.
- the switching control unit 41 inputs the control signal Vsel3 generated based on the obtained determination result (determination signal Vch) to the current control unit 42, and the current control unit 42 is a constant current driven by the minimum cathode terminal voltage Vfb3.
- the source 23 is turned off.
- the switching control unit 41 controls the switching circuits 30 and 31 by the control signals Vsel1 and Vsel2 to switch the connection relating to the LED string load 13 having the minimum cathode terminal voltage Vfb3 (that is, the maximum forward voltage drop). .
- the switching control unit 41 switches the connection destination of the anode terminal P3H of the LED string load 13 from the output terminal PO2 of the voltage conversion circuit 2 to the output terminal PO1 of the voltage conversion circuit 1.
- the switching control unit 41 switches the connection destination of the cathode terminal P3L from the minimum value detection unit 34 to the minimum value detection unit 32.
- each cathode terminal voltage and the switching of the connection of the LED string load are performed by a half of the total number of LED string loads, so that an equal number of LEDs can be obtained based on the magnitude of the forward voltage drop.
- the column load can be distributed to the two voltage conversion circuits 1 and 2 (see FIG. 7).
- the LED column loads as shown in FIG. 6 are forwarded by rearranging the LED column loads by using a plurality of voltage conversion circuits based on the cathode terminal voltages Vfb1 to Vfb4 of the LED column loads. It is possible to reduce the total value of the voltages Vp1 to Vp3 corresponding to the variations of the voltage drops Vf1 to Vf4 to the total value of the voltages Vp1 ′ and Vp2 ′ corresponding to the variations as shown in FIG. Therefore, power consumption can be reduced. For example, it is assumed that Vf1 is 10V, Vf2 is 11V, Vf3 is 12V, and Vf4 is 13V. At this time, Vp1 shown in FIG.
- Vp2 is 2V
- Vp3 is 1V
- the total value is 6V
- Vp1 'and Vp2' shown in FIG. 7 are both 1V
- the total value is 2V.
- the number of recombination processes is set so that the number of LED string loads connected to the voltage conversion circuits 1 and 2 is substantially the same. Half (in this embodiment, twice).
- the number of recombination processes for realizing the function of the present invention is not limited to this.
- the number of LED string loads connected to each voltage application unit can be made uniform, and the load on the voltage application unit can be made uniform. More generally, if the total number of voltage application units is M and the total number of connected light emitting element arrays is N, N / M light emitting element arrays may be connected to one voltage application unit. Therefore, by repeating the recombination process for one voltage application unit N / M times, it is possible to obtain the optimum number of connected light emitting element arrays for making the load uniform.
- M and N are positive integers
- M ⁇ N are positive integers
- the LED array load is reconfigured based on the determination result (determination signal Vch).
- the switching circuits 30 and 31 may be finally controlled by the switching control unit 41 to rearrange the LED strings. At that time, by storing the determination result (determination signal Vch) for each time in the switching control unit 41, it is possible to realize a desired LED row load distribution.
- the VF determination unit 40 may determine the maximum value instead of determining the minimum value of each cathode terminal voltage Vfb1 to Vfb4. In other words, the VF determination unit 40 identifies a constant current source to which the maximum cathode terminal voltage is applied, and notifies the switching control unit 41 of the determination result (determination signal Vch). In this case, the switching control unit 41 repeats the operation of turning off the constant current source to which the maximum cathode terminal voltage is applied based on the obtained determination result (determination signal Vch) by a predetermined number of times. It is also possible to perform sorting. In other words, the switching unit may be controlled so that the light emitting element row having the minimum forward voltage drop among the light emitting element rows connected to the voltage application unit is connected to another voltage application unit.
- the voltage conversion circuit 1 is configured as a boost conversion circuit that converts a predetermined input voltage Vcc into a higher voltage and outputs the converted voltage.
- a step-down conversion circuit that converts the predetermined input voltage Vcc to a lower voltage and outputs the converted voltage may be used, or from the predetermined input voltage Vcc
- a step-up / down conversion circuit that can convert and output a low voltage or a high voltage may be used.
- column load which is a light emitting element row
- column was set as the structure which connected 4 LEDs in series, However, It is not restricted to this. Any one or more LEDs can be applied. That is, one light emitting element row is composed of one or more light emitting elements.
- FIG. 8 is a block diagram showing an example of the overall configuration of the light emitting element driving apparatus according to Embodiment 2.
- the voltage conversion circuit 3 is a step-up switching power supply, and includes a coil L3, a diode D3, a transistor M3, and a capacitor C3. Based on the control signal Vpwm3 from the PWM control unit 37, the voltage conversion circuit 3 boosts a predetermined input voltage Vcc to a voltage Vout3 necessary for driving the LED string loads 11 to 14, and outputs a voltage Vout3.
- the switching circuit 30 is a selector circuit group having selectors 30a to 30f. Based on the control signal Vsel1 from the switching control unit 41, the switching circuit 30 converts the anode terminals P1H to P6H of the LED string loads 11 to 16 to the output terminal PO1 of the voltage conversion circuit 1 and the output of the voltage conversion circuit 2, respectively. It is connected to either the terminal PO2 or the output terminal PO3 of the voltage conversion circuit 3.
- the selectors 30a to 30f are configured by, for example, MOS switches or the like.
- the constant current sources 25 and 26 are connected in series to the cathode terminals P5L and P6L of the LED string loads 15 and 16, respectively, and supply constant currents I5 and I6 necessary for LED emission to the LED string loads 15 and 16, respectively.
- the constant current sources 25 and 26 can be turned on / off based on the control signal Vcnt from the current control unit 42, and adjust the ratio of the on time and the off time. Thereby, the electric current amount supplied to LED row load 15 and 16 can be adjusted, and the light emission amount of LED can be controlled.
- the switching circuit 31 is a selector circuit group having selectors 31a to 31f. Based on the control signal Vsel2 from the switching control unit 41, the switching circuit 31 converts each of the cathode terminal voltages Vfb1 to Vfb6 to either the minimum value detection unit 32, the minimum value detection unit 34, or the minimum value detection unit 36. Connect to crab.
- the selectors 31a to 31f are configured by MOS switches, for example.
- the cathode terminal voltages Vfb1 to Vfb6 of the LED string loads 11 to 16 are determined based on the forward voltage drop of the LED string loads 11 to 16.
- the minimum value detection unit 36 selects the minimum voltage among the cathode terminal voltages connected by the switching circuit 31, and inputs the selected voltage to the PWM control unit 37 as the detection voltage Vdet3.
- the detection voltage Vdet3 does not need to be the same voltage as the selected minimum cathode terminal voltage.
- the detection voltage Vdet3 is based on the minimum cathode terminal voltage obtained by shifting the minimum value of each cathode terminal voltage by a predetermined voltage. The voltage generated may be used.
- the PWM control unit 37 compares the input detection voltage Vdet3 with a reference signal Vref (not shown). Based on the comparison result, the control signal Vpwm3 is input to the gate of the transistor M3 of the voltage conversion circuit 3 so that the detection voltage Vdet3 becomes equal to the reference voltage Vref. Based on the control signal Vpwm3, the voltage conversion circuit 3 performs switching of the transistor M3 to generate an output voltage Vout3.
- the VF determination unit 40 determines the magnitude relationship between the forward voltage drops in the LED string loads 11 to 16, and switches the determination signal Vch, which is the determination result, to the switching control unit 41. To enter.
- the LED string loads 11 to 16 are classified into three groups based on the magnitude of the forward voltage drop, and the three classified LED string load groups are each converted into three voltage conversions. Driven by circuits 1 to 3. That is, as shown in the first embodiment, the forward direction in the LED array load group connected to each voltage conversion circuit is greater than that in the case of using a light emitting element driving device that is driven by two voltage conversion circuits. It is possible to reduce the variation width of the voltage drop. For this reason, further power consumption reduction can be realized.
- the operation sequence of the light emitting element driving apparatus according to the second embodiment will be briefly described with reference to the flowchart shown in FIG.
- the operation shown in FIG. 5 of the first embodiment is different in that the LED string loads are classified into three groups instead of two, and each is divided into three voltage conversion circuits 1 to 3.
- the anode terminals P1H to P6H of all the LED string loads are connected to the output terminal PO3 of the voltage conversion circuit 3, and the cathode terminals P1L to P6L are connected to the minimum value detector 36. That is, all the LED string loads 11 to 16 are connected to the system of the voltage conversion circuit 3 (voltage conversion unit having the voltage conversion circuit 3) (step S71). Then, all the constant current sources 21 to 26 are turned on, and all the LED string loads 11 to 16 are driven (step S72).
- the VF determination unit 40 determines a constant current source to which the minimum cathode terminal voltage is applied among the constant current sources that are turned on (step S73). Then, the VF determination unit 40 notifies the switching control unit 41 of the determination result (determination signal Vch) (step S74).
- the switching control unit 41 turns off the constant current source to which the minimum cathode terminal voltage is applied via the current control unit 42 (step S75).
- the switching control unit 41 controls the switching circuits 30 and 31 to change the connection destination of the LED string load connected to the constant current source turned off from the system of the voltage conversion circuit 3 to the system of the voltage conversion circuit 1. (Step S76).
- step S77 the same determination and switching of connection to the voltage conversion circuit 1 are repeated for the remaining constant current source and the LED string load, the number of times corresponding to 1/3 of the total number of LED string loads. This is performed (step S77).
- steps S73 to S77 are performed for the remaining constant current sources that are turned on corresponding to 2/3 of the total number of LED string loads and the LED string loads (steps S78 to S82). ). However, in steps S78 to S82, the connection destination of the LED string load connected to the turned off constant current source is switched from the voltage conversion circuit 3 system to the voltage conversion circuit 2 system.
- the total LED string loads are classified into three groups each including an equal number of LED string loads (a number corresponding to 1/3 of the total LED string load number) based on the magnitude of the forward voltage drop. Is done. More specifically, all the LED string loads can be distributed to the voltage conversion circuit 1, the voltage conversion circuit 2, and the voltage conversion circuit 3 in descending order of the forward voltage drop.
- the number of recombination processes is set to 1/3 of the number of LED string loads (this embodiment) so that the number of LED string loads connected to each of the voltage conversion circuits 1 to 3 is substantially the same. In the form of 3).
- the number of recombination processes for realizing the function of the present invention is not limited to this.
- the number of LED string loads connected to each voltage application unit can be made uniform, and the load on the voltage application unit can be made uniform. More generally, if the total number of voltage application units is M and the total number of connected light emitting element arrays is N, N / M light emitting element arrays may be connected to one voltage application unit.
- the LED array load is reconfigured based on the determination result (determination signal Vch).
- the switching circuits 30 and 31 may be finally controlled by the switching control unit 41 to rearrange the LED strings. At that time, by storing the determination result (determination signal Vch) for each time in the switching control unit 41, it is possible to realize a desired LED row load distribution.
- the VF determination unit 40 determines the constant current source to which the maximum cathode terminal voltage is applied by determining the maximum value of each cathode terminal voltage Vfb1 to Vfb6, and switches the determination result (determination signal Vch). 41 may be notified. In this case, the switching control unit 41 repeats the operation of turning off the constant current source to which the maximum cathode terminal voltage is applied based on the obtained determination result (determination signal Vch) by a predetermined number of times. It is also possible to perform sorting.
- the number of voltage conversion circuits and the number of classifications of LED string loads based on the magnitude of the forward voltage drop are three, respectively, but the circuit configuration for realizing the function of the present invention Is not limited to this. That is, in the same manner as the application from the first embodiment to the second embodiment, the number of classifications of the LED string loads is set to four or more, so that the variation width of the forward voltage of the LED string load in each voltage conversion circuit can be reduced. Further reduction can be achieved. For this reason, the power consumption can be further reduced.
- FIG. 10 is a block diagram showing an example of the overall configuration of the light emitting element driving apparatus according to Embodiment 3.
- the control unit controls the switching unit to connect all the light emitting element columns to the same voltage applying unit, and then the light emitting element columns connected to the voltage applying unit.
- the switching unit is controlled to connect the column to a further voltage application unit. Details will be described below using a specific configuration.
- the VF determination unit 40b of the second embodiment is that the constant current source to which the minimum cathode terminal voltage is applied and the constant current source to which the maximum cathode terminal voltage is applied are simultaneously determined among the cathode terminal voltages Vfb1 to Vfb6. Different from the VF determination unit 40.
- the VF determination unit 40b determines a constant current source to which the minimum cathode terminal voltage is applied among the constant current sources that are turned on, and notifies the switching control unit 41b of the result as a determination signal Vch1. Further, the VF determination unit 40b determines a constant current source having the maximum cathode terminal voltage among the constant current sources that are turned on, and notifies the switching control unit 41b of the result as a determination signal Vch2.
- the switching control unit 41b is different from the switching control unit 41 of the second embodiment in that switching to a system of two or more different voltage conversion circuits is simultaneously performed for a plurality of LED string loads.
- the switching control unit 41b generates control signals Vsel1 to 3 based on the input determination results (determination signals Vch1 and Vch2), and controls the switching circuits 30 and 31 and the current control unit 42 using the control signals Vsel1 to 3. .
- the switching operation of the voltage conversion circuit system (voltage application unit) can be simultaneously performed for two LED string loads by one determination by the VF determination unit 40b. . For this reason, there is an effect that the time required for a series of operations of grouping the LED string loads and distributing them to a plurality of voltage conversion circuits can be reduced to about half.
- the VF determination unit 40b determines that the cathode terminal voltage Vfb6 applied to the constant current source 26 is the smallest among the constant current sources that are turned on (determination signal Vch1), and the cathode terminal voltage Vfb1 applied to the constant current source 21. Is determined to be maximum (determination signal Vch2) and the switching control unit 41b is notified.
- the switching control unit 41b turns off the constant current source 21 to which the maximum cathode terminal voltage Vfb1 is applied and the constant current source 26 to which the minimum cathode terminal voltage Vfb6 is applied via the current control unit 42.
- the switching control unit 41b controls the switching circuits 30 and 31 based on the determination result (determination signal Vch1) to switch the connection related to the LED string load 16 having the minimum cathode terminal voltage Vfb6.
- the switching control unit 41 b switches the connection destination of the LED string load 16 from the voltage conversion circuit 2 system to the voltage conversion circuit 1 system.
- the switching control unit 41b controls the switching circuits 30 and 31 based on the determination result (determination signal Vch2) to switch the connection related to the LED string load 11 having the maximum cathode terminal voltage Vfb1. Specifically, the switching control unit 41 b switches the connection destination of the LED string load 11 from the system of the voltage conversion circuit 2 to the system of the voltage conversion circuit 3.
- the LED string loads are grouped by two from the descending order of the forward voltage drop, and each voltage conversion is performed. It is distributed to the circuit 1, the voltage conversion circuit 2, and the voltage conversion circuit 3.
- the LED string load distribution is performed only by two determination operations. The operation can be terminated.
- the number of recombination processes is set to 1/3 of the number of LED string loads (this embodiment) so that the number of LED string loads connected to each of the voltage conversion circuits 1 to 3 is substantially the same. In the form of 3).
- the number of recombination processes for realizing the function of the present invention is not limited to this.
- the number of LED string loads connected to each voltage application unit can be made uniform, and the load on the voltage application unit can be made uniform. More generally, if the total number of voltage application units is M and the total number of light emitting element arrays is N, N / M light emitting element arrays may be connected to one voltage application unit.
- the light emitting element driving apparatus has an effect of reducing the time required for distributing a series of LED row loads.
- FIG. 11 is a block diagram illustrating an example of the overall configuration of a light emitting element driving apparatus according to Embodiment 4.
- the control unit controls the switching unit to connect all the light emitting element rows to the same voltage application unit, and then a plurality of current sources connected to the cathode ends of the light emitting element rows.
- the switching section is controlled so that the light emitting element array having the current source voltage exceeding the threshold voltage is connected to another voltage application section by comparing the current source voltage applied to and a predetermined threshold voltage. Details will be described below using a specific configuration.
- the voltage comparison unit 44 compares the cathode terminal voltages Vfb1 to Vfb4 with a predetermined threshold voltage Vth and notifies the switching control unit 41 of the obtained comparison result (determination signal Vch).
- the voltage comparison unit 44 can be realized by a configuration in which the cathode terminal voltages Vfb1 to Vfb4 and the threshold voltage Vth are compared by the comparators 44a to 44d, respectively.
- the voltage comparison unit 44 compares the cathode terminal voltages Vfb1 to Vfb4 with the threshold voltage Vth, and notifies the switching control unit 41 of the comparison result.
- the switching control unit 41 turns off the constant current sources 21 and 22 to which the cathode terminal voltages Vfb1 and Vfb2 larger than the threshold voltage Vth are applied via the current control unit 42 based on the comparison result (determination signal Vch). Further, the switching circuits 30 and 31 are controlled to switch the connection destination of the LED string loads 11 and 12 from the system of the voltage conversion circuit 1 to the system of the voltage conversion circuit 2.
- the LED string loads 11 to 14 can be classified based on the magnitude of the forward voltage drop, and can be distributed to the voltage conversion circuit 1 and the voltage conversion circuit 2.
- the number of LED string loads connected to each voltage conversion circuit may not be uniform depending on the value of the threshold voltage Vth.
- the LED string loads can be classified by a single comparison between the cathode terminal voltages Vfb1 to Vfb4 and the threshold voltage Vth by the voltage comparison unit 44. Therefore, the time required for distributing the LED string loads can be reduced. Has the effect of shortening.
- the switching unit is controlled so that a light emitting element array having a current source voltage exceeding the threshold voltage is connected to another voltage application unit.
- the configuration may be such that the switching unit is controlled so that a light emitting element array having a current source voltage smaller than the threshold voltage is connected to another voltage application unit. Even in such a configuration, the same effect can be obtained.
- line which has a current source voltage equal to a threshold voltage may also be connected to another voltage application part may be sufficient.
- three or more voltage conversion circuits are provided, and a plurality of threshold voltages Vth are provided accordingly, and each cathode terminal voltage is compared with a plurality of different threshold voltages Vth. Based on the comparison result, three or more of a plurality of voltage conversion circuits are provided. It is good also as a structure which distributes LED row load to a voltage conversion circuit.
- FIG. 13 is a block diagram showing an example of the overall configuration of the light emitting element driving apparatus according to Embodiment 5.
- the control unit when the total number of voltage application units is M and each voltage application unit is the first to Mth voltage application units, the control unit is connected to the Nth voltage application unit.
- the light emitting element row having the maximum forward voltage drop among the connected light emitting element rows is connected to the (N ⁇ 1) th voltage applying unit, and the light emitting element row connected to the Nth voltage applying unit is connected.
- the switching unit is controlled so that the light emitting element array having the smallest forward voltage drop among them is connected to the (N + 1) th voltage applying unit.
- the configuration including the voltage conversion circuit 1, the minimum value detection unit 32, and the PWM control unit 33 is a specific example of one voltage application unit.
- the configuration including the switching circuits 30 and 90 is a specific example of the switching unit.
- the configuration including the switching control unit 41c and the address detection circuits 71 to 73 is a specific example of the control unit.
- the LED array loads 11 to 19 are specific examples of light emitting element arrays. Hereinafter, it demonstrates in detail using a concrete structure.
- the switching circuit 30 is a selector circuit group having selectors 30a to 30i. Based on the control signal Vsel10 from the switching control unit 41c, the switching circuit 30 connects the anode terminals of the LED string loads 11 to 19 to the output terminal of the voltage conversion circuit 1, the output terminal of the voltage conversion circuit 2, or the voltage conversion, respectively. Connect to one of the output terminals of the circuit 3.
- the selectors 30a to 30i are constituted by, for example, MOS switches or the like.
- the constant current sources 21 to 29 are connected in series to the cathode terminals of the LED string loads 11 to 19, respectively, and supply constant currents I1 to I9 necessary for LED emission to the LED string loads 11 to 19, respectively.
- the constant currents 21 to 29 are on / off controlled by a logic circuit (not shown) or a microcomputer.
- the switching circuit 90 is a selector circuit group having selectors 90a to 90i.
- Each of the selectors 90a to 90c converts any one of the cathode terminal voltages Vfb1 to Vfb9 of the LED string loads 11 to 19 into the minimum value detection unit 36 and the address detection unit 73 based on the control signal Vsel11 from the switching control unit 41c.
- each of the selectors 90d to 90f selects any one of the cathode terminal voltages Vfb1 to Vfb9 of the LED string loads 11 to 19 based on the control signal Vsel11 from the switching control unit 41c, and the minimum value detection unit 34 and the address detection.
- the unit 72 Connected to the unit 72.
- each of the selectors 90g to 90h selects any one of the cathode terminal voltages Vfb1 to Vfb9 of the LED column loads 11 to 19 based on the control signal Vsel11 from the switching control unit 41c, and the minimum value detection unit 32 and the address detection. Connect to the unit 71.
- the selectors 90a to 90i are constituted by, for example, MOS switches or the like.
- the address detection unit 71 detects a string address of one specific LED column load among the LED column loads 11 to 19 and inputs it to the switching control unit 41c as an address signal MaxAdr1.
- the LED column load having the string address that becomes the address signal MaxAdr1 is the LED having the largest cathode terminal voltage among the three cathode terminal voltages input to the address detection unit 71 via the selectors 90g, 90h, and 90i. It is a column load. This is an LED string load with minimal forward voltage drop.
- the address detection unit 72 detects the string addresses of two specific LED column loads among the LED column loads 11 to 19, and inputs them to the switching control unit 41c as address signals MaxAdr2 and MinAdr2.
- the LED column load having the string address that becomes the address signal MaxAdr2 is the LED having the largest cathode terminal voltage among the three cathode terminal voltages input to the address detection unit 72 via the selectors 90d, 90e, and 90f. It is a column load. This is an LED string load with minimal forward voltage drop.
- the LED string load having a string address that becomes the address signal MinAdr2 is an LED string having the smallest cathode terminal voltage among the three cathode terminal voltages input to the address detection unit 72 via the selectors 90d, 90e, and 90f. It is a load. This is the LED string load with the largest forward voltage drop.
- the address detection unit 73 detects a string address of one specific LED column load among the LED column loads 11 to 19 and inputs it to the switching control unit 41c as an address signal MinAdr3.
- the LED string load having the string address that becomes the address signal MinAdr3 is the LED having the smallest cathode terminal voltage among the three cathode terminal voltages input to the address detection unit 73 via the selectors 90a, 90b, and 90c. It is a column load. This is the LED string load with the largest forward voltage drop.
- the string address means address information for identifying each LED column load 11-19.
- the switching control unit 41c controls the switching circuits 30 and 90 by associating the address information obtained from the address detection units 71 to 73 with any one of the voltage conversion circuits 1 to 3, and rearranges the LED string load.
- the switching control unit 41c controls the switching circuits 30 and 90 by the control signals Vsel10 to Vsel11 generated based on the input address signals MaxAdr1, MaxAdr2, MinAdr2, and MinAdr3. Specifically, the LED string load having the address indicated by the address signal MaxAdr1 is replaced with the LED string load having the address indicated by the address signal MinAdr2. Further, the LED string load having the address indicated by the address signal MaxAdr2 and the LED string load having the address indicated by the address signal MinAdr3 are switched. When recombination of the same addresses is repeated a predetermined number of times between the voltage conversion circuits, the reconfiguration control of the LED string load between the voltage conversion circuits is terminated.
- the switching circuit 41c is configured by a logic circuit or a microcomputer, for example.
- the LED string loads 11 to 19 are classified into three groups based on the magnitude of the forward voltage drop by a sequence different from that of the second embodiment, and the classified three LED string loads are classified.
- Each group is driven by three voltage conversion circuits 1 to 3. That is, the plurality of LED string load groups grouped based on the magnitude of the forward voltage drop are shared by the plurality of voltage conversion circuits to drive. Thereby, the variation amount of the forward voltage drop in the LED string load group connected to each voltage conversion circuit is reduced, and the power consumption is reduced.
- LED string loads 11, 15, and 16 the magnitudes of forward voltage drops are 11V, 15V, and 16V, respectively
- the voltage conversion circuit 3 is connected to LED string loads 12, 13, and 19 (the magnitudes of forward voltage drops are 12V, 13V, and 19V, respectively).
- the voltage conversion circuits 1 to 3 are controlled by the PWM control units 33 to 37 so that the minimum cathode terminal voltage among the cathode terminal voltages of the connected LED string loads is 1V.
- the address signal MaxAdr1 indicates the address of the LED string load 14.
- the address signal MaxAdr2 indicates the address of the LED string load 11. Since the LED string load having the smallest cathode terminal voltage among the LED string loads connected to the voltage conversion circuit 2 is the LED string load 16, the address signal MinAdr2 indicates the address of the LED string load 16.
- the address signal MinAdr3 indicates the address of the LED string load 19.
- the same LED string load rearrangement was repeated twice.
- the control unit finishes the control of the switching unit, and is optimal with simple and minimal recombination. Recombination to the correct state can be completed.
- the LED string loads 11 to 19 can be classified based on the magnitude of the forward voltage drop and distributed to the voltage conversion circuit 1, the voltage conversion circuit 2, and the voltage conversion circuit 3. it can.
- Embodiment 6 An operation sequence of the light emitting element driving device according to Embodiment 6 of the present invention will be described with reference to FIG.
- This embodiment is different from the light emitting element driving apparatus according to the third embodiment shown in FIG. 10 in the use of the voltage conversion circuit used for determining the drive voltage of the LED string load.
- the VF determination unit 40b is a VF determination unit 40 ′
- the switching control unit 41b is a switching control unit 41 ′, and their operations are different.
- the control unit controls all the light-emitting element columns that are driven after controlling the switching unit so as to evenly connect all the light-emitting element columns to all the voltage application units.
- the switching unit controlling the switching unit to connect the light emitting element array having the maximum forward voltage drop to the first voltage application unit to turn off the driving of the light emitting element array having the maximum forward voltage drop.
- the switching unit is controlled to connect the light emitting element row having the minimum forward voltage drop among all the driven light emitting element rows to the second voltage application unit, and the minimum forward voltage drop is controlled.
- the driving of the light-emitting element array is turned off. Details will be described below using a specific example.
- the switching circuits 30 and 31 are controlled so that the LED string loads are evenly connected to the respective voltage conversion circuits, and the cathode terminals of the LED string loads are connected to the corresponding minimum value detectors (step S131).
- the voltages of all the voltage conversion circuits are set to the same voltage so that all the LED string loads can be turned on (step S132).
- all the LED string loads are driven by turning on all the constant current sources 21 to 26 (step S133).
- the VF determination unit 40 detects the minimum cathode terminal voltage Vfb6 and the maximum cathode terminal voltage Vfb1 among the cathode terminal voltages Vfb1 to Vfb6 applied to the constant current sources 21 to 26 that are turned on. As a result, the VF determination unit 40 ′ determines which constant current source is driven with the minimum cathode terminal voltage and which constant current source is driven with the maximum cathode terminal voltage (step) S134). Then, the VF determination unit 40 'notifies the determination result (determination signal Vch) to the switching control unit 41' (step S135).
- the switching control unit 41 ′ inputs the control signal Vsel 3 generated based on the determination result to the current control unit 42.
- the current control unit 42 turns off the constant current source 26 to which the minimum cathode terminal voltage is applied and the constant current source 21 to which the maximum cathode voltage is applied (step S136).
- the switching control unit 41 ′ controls the switching circuits 30 and 31 by the control signals Vsel 1 and Vsel 2 to switch the connection relating to the LED string loads 11 and 16 having the maximum and minimum cathode terminal voltages Vfb 1 and Vfb 6. Specifically, the switching control unit 41 ′ switches the connection destination of the anode terminal P6H of the LED string load 16 to the output terminal PO1 of the voltage conversion circuit 1, and switches the connection destination of the cathode terminal P6L to the minimum value detection unit 32. (If it was originally connected, leave it as it is.) That is, the LED string load 16 having the maximum forward voltage drop is connected to the first voltage application unit configured by the voltage conversion circuit 1 and the minimum value detection unit 32.
- the switching control unit 41 ′ switches the connection destination of the anode terminal P1H of the LED string load 11 to the output terminal PO3 of the voltage conversion circuit 3, and makes the connection destination of the cathode terminal P1L to the minimum value detection unit 36. Switch (if left connected, leave it alone). That is, the LED string load 11 having the minimum forward voltage drop is connected to the second voltage application unit configured by the voltage conversion circuit 3 and the minimum detection unit 36 (step S137).
- step S134 to step S137 are repeated by the number corresponding to 1/3 of the number of LED string loads, that is, the number of times equal to the value obtained by dividing the number of LED string loads by the number of voltage application units (step S138). ). In the present embodiment, steps S134 to S137 are repeated twice. The LED string load that is not selected in the above determination is connected to the voltage conversion circuit 2 and the recombination is completed.
- the number of recombination processes is set to 1/3 of the number of LED string loads (this embodiment) so that the number of LED string loads connected to each of the voltage conversion circuits 1 to 3 is substantially the same. In the form of 3).
- the number of recombination processes for realizing the function of the present invention is not limited to this.
- the number of LED string loads connected to each voltage application unit can be made uniform, and the load on the voltage application unit can be made uniform. More generally, if the total number of voltage application units is M and the total number of connected light emitting element arrays is N, N / M light emitting element arrays may be connected to one voltage application unit.
- the voltages of all the voltage conversion circuits are set to the same voltage that can light all the LED string loads, and the minimum drive voltage and the maximum drive voltage are determined. That is, in the third embodiment, all the LED string loads are first connected to one voltage conversion circuit, and the burden on the voltage conversion circuit increases. Therefore, the voltage conversion circuit is compared with other voltage conversion circuits. Large capacity is required. On the other hand, in the present embodiment, the number of LED string loads connected to the voltage conversion circuit is approximately the same during and after the drive voltage determination. For this reason, the scale and the component specifications of the voltage conversion circuit are also equal, and there is an effect of minimizing the design man-hour and the component type.
- FIG. 16 is a schematic configuration diagram of a liquid crystal display device including the planar illumination device according to the embodiment of the present invention.
- the liquid crystal display device 1400 includes a liquid crystal panel 1410 and a planar illumination device 1420.
- the liquid crystal display device 1400 includes a liquid crystal panel control unit 1430 and a backlight control unit 1440.
- the liquid crystal panel control unit 1430 controls the light transmittance of each pixel (not shown) included in the liquid crystal panel 1410 based on the input video signal.
- the backlight control unit 1440 controls the intensity of illumination light illuminated by the planar illumination device 1420 for each predetermined light emitting area based on the input video signal.
- the planar illumination device 1420 includes a plurality of light emitting elements 1421, a base 1422 made of a substrate and a reflecting plate on which the light emitting elements 1421 are mounted, and an optical sheet for making light emitted from the light emitting elements 1421 into uniform planar light. 1423.
- the light emitting element 1421 is an LED or the like that emits white light.
- the optical sheet 1423 may be composed of a plurality of optical sheets such as a diffusion plate and a brightness enhancement film.
- the planar lighting device 1420 includes a light emitting element driving device 1424 that drives the light emitting element 1421 based on a signal output from the backlight control unit 1440.
- the light emitting device driving device 1424 is the light emitting element driving device according to any one of Embodiments 1 to 6 described above.
- the liquid crystal panel 1410 receives illumination light from the planar illumination device 1420 from the back, and spatially modulates the illumination light in accordance with a video signal to display an image.
- the planar illumination device having the light emitting element driving device 1424 suppresses an increase in power consumption caused by variations in forward voltage of LEDs. I can do it.
- the light emitting element driving device 1424 is provided, thereby configuring a liquid crystal display device that suppresses an increase in power consumption caused by variations in forward voltage of LEDs. I can do it.
- a liquid crystal display device such as a liquid crystal television or a liquid crystal monitor
- a planar illumination device used as a backlight thereof
- a light emitting element driving device used for the backlight.
Abstract
Description
本発明の実施の形態1に係る発光素子駆動装置について、図3~図6を用いて説明する。図3は、実施の形態1に係る発光素子駆動装置の全体構成例を示すブロック図である。図3に示すように、この発光素子駆動装置は、電圧変換回路1~2と、切り替え回路30~31と、定電流源21~24と、最小値検出部32、34と、PWM制御部33、35と、VF判定部40と、切り替え制御部41と、電流制御部42と、を備え、LED列負荷11~14を駆動する。
本発明の実施の形態2に係る発光素子駆動装置について、図8~9を用いて説明する。実施の形態2では、実施の形態1に係る発光素子駆動装置と比較して、主に、電圧変換回路3と、LED列負荷15、16と、定電流源25、26と、セレクタ30e~30fと、セレクタ31e~31fと、最小値検出部36と、PWM制御部37と、が付加されている点で異なる。図8は、実施の形態2に係る発光素子駆動装置の全体構成例を示すブロック図である。
本発明の実施の形態3に係る発光素子駆動装置について、図10を用いて説明する。実施の形態3では、実施の形態2に係る発光素子駆動装置と比べて、主に、VF判定部40とは異なるVF判定部40bと、切り替え制御部41とは異なる切り替え制御部41bと、を有する点で異なる。図10は、実施の形態3に係る発光素子駆動装置の全体構成例を示すブロック図である。本実施の形態の発光素子駆動装置において、制御部は、全ての発光素子列を同一の電圧印加部に接続するように切替部を制御した後、当該電圧印加部に接続されている発光素子列の中で最大の順方向電圧降下を有する発光素子列を別の電圧印加部に接続するとともに、当該電圧印加部に接続されている発光素子列の中で最小の順方向電圧降下を有する発光素子列をさらに別の電圧印加部に接続するように切替部を制御する。以下、具体構成を用いて詳細を説明する。
本発明の実施の形態4に係る発光素子駆動装置について、図11および図12を用いて説明する。本実施の形態では、実施の形態1に係る発光素子駆動装置と比べ、主として、VF判定部40とは異なる電圧比較部44と、新たに閾値電圧Vthと、を有する点で異なる。図11は、実施の形態4に係る発光素子駆動装置の全体構成例を示すブロック図である。本実施の形態において、制御部は、全ての発光素子列を同一の電圧印加部に接続するように切替部を制御した後、当該発光素子列の各々のカソード端に接続された複数の電流源にかかる電流源電圧と所定の閾値電圧とを比較して、閾値電圧を超える電流源電圧を有する発光素子列を別の電圧印加部に接続するように切替部を制御する。以下、具体構成を用いて詳細を説明する。
本発明の実施の形態5に係る発光素子駆動装置について、図13および図14を用いて説明する。本実施の形態では、実施の形態2に係る発光素子駆動装置と比べ、主として、切り替え制御部41とは異なる切り替え制御部41cと、切り替え回路31とは異なる切り替え回路90と、新たにセレクタ30g~30iと、LED列負荷17~19と、定電流源27~29と、アドレス検出部71~73と、を有する点が異なる。図13は、実施の形態5に係る発光素子駆動装置の全体構成例を示すブロック図である。本実施の形態では、発光素子駆動装置において、電圧印加部の全数がM、それぞれの電圧印加部を第1~第Mの電圧印加部とするとき、制御部は、第Nの電圧印加部に接続されている発光素子列の中で最大の順方向電圧降下を有する発光素子列を第N-1の電圧印加部に接続するとともに、第Nの電圧印加部に接続されている発光素子列の中で最小の順方向電圧降下を有する発光素子列を第N+1の電圧印加部に接続するように切替部を制御する。なお、本実施の形態においては、電圧変換回路1、最小値検出部32、およびPWM制御部33を合わせた構成は、1つの電圧印加部の具体例である。また、切り替え回路30、90を合わせた構成は、切替部の具体例である。また、切り替え制御部41c、アドレス検出回路71~73を合わせた構成は、制御部の具体例である。また、LED列負荷11~19は、それぞれ発光素子列の具体例である。以下、具体構成を用いて詳細に説明する。
本発明の実施の形態6に係る発光素子駆動装置の動作シーケンスについて、図15を用いて説明する。本実施の形態は、図10に示す実施の形態3による発光素子駆動装置と比べ、LED列負荷の駆動電圧判定に用いる電圧変換回路の用い方が異なる。具体的には、VF判定部40bがVF判定部40’に、切り替え制御部41bが切り替え制御部41’となっており、その動作が異なる。本実施の形態では、発光素子駆動装置において、制御部は、全ての発光素子列を全ての電圧印加部に均等に接続するように切替部を制御した後、駆動している全ての発光素子列の中で最大の順方向電圧降下を有する発光素子列を第1の電圧印加部に接続するように切替部を制御して当該最大の順方向電圧降下を有する発光素子列の駆動をオフするとともに、駆動している全ての発光素子列の中で最小の順方向電圧降下を有する発光素子列を第2の電圧印加部に接続するように切替部を制御して当該最小の順方向電圧降下を有する発光素子列の駆動をオフする。以下、具体例を用いて、詳細を説明する。
次に、本発明の実施の形態に係る面状照明装置を有する液晶表示装置について説明する。図16は、本発明の実施の形態に係る面状照明装置を備えた液晶表示装置の概略構成図である。
11、12、13、14、15、16、17、18、19 LED列負荷
21、22、23、24、25、26、27、28、29 定電流源
30、31 切り替え回路
30a、30b、30c、30d、30e、30f、30g、30h、30i セレクタ
31a、31b、31c、31d、31e、31f セレクタ
32、34、36 最小値検出部
33、35、37 PWM制御部
40、40b、40’ VF判定部
41、41b、41c、41’ 切り替え制御部
42 電流制御部
44 電圧比較部
44a、44b、44c、44d 比較器
50 定電流源
51、52、53、54 pnpトランジスタ
55、56、57、58 抵抗
59、60、61、62 バッファ回路
71、72、73 アドレス検出部
90 切り替え回路
90a、90b、90c、90d、90e、90f、90g、90h、90i セレクタ
100 電圧変換回路
101 コイル
102 ダイオード
103 トランジスタ
104 コンデンサ
110、111、112、113 LED列負荷
120、121、122、123 定電流源
130 選択回路
131 制御回路
1400 液晶表示装置
1410 液晶パネル
1420 面状照明装置
1421 発光素子
1422 ベース
1423 光学シート
1424 発光素子駆動装置
1430 液晶パネル制御部
1440 バックライト制御部
Claims (23)
- 複数の発光素子列の順方向電圧降下の内、最大の順方向電圧降下に基づいて定まる検出電圧に基づいて印加電圧を生成し、生成された印加電圧を前記複数の発光素子列に印加する複数の電圧印加部と、
前記複数の発光素子列が個別に接続される電圧印加部を前記複数の電圧印加部の内で切り替える切替部と、
前記複数の発光素子列の順方向電圧降下の差が最小となるように前記切替部に接続を切り替えさせる制御を行う制御部と、を備える、
発光素子駆動装置。 - 前記検出電圧は、前記複数の発光素子列の各々のカソード端に接続された複数の電流源にかかる電流源電圧の内、最小の電圧である、
請求項1記載の発光素子駆動装置。 - 前記制御部は、前記複数の発光素子列の全てを前記複数の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記同一の電圧印加部に接続されている発光素子列の中で最大の順方向電圧降下を有する発光素子列を別の電圧印加部に接続するように前記切替部を制御する、
請求項1記載の発光素子駆動装置。 - 前記制御部は、前記複数の発光素子列の全てを前記複数の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記同一の電圧印加部に接続されている発光素子列の中で最小の順方向電圧降下を有する発光素子列を別の電圧印加部に接続するように前記切替部を制御する、
請求項1記載の発光素子駆動装置。 - 前記電圧印加部の個数をM、前記発光素子列の個数をNとすると、
前記制御部は、N個の発光素子列の全てをM個の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記同一の電圧印加部に接続されている発光素子列の中で最大の順方向電圧降下を有する発光素子列を別の電圧印加部に接続するように前記切替部を制御する処理をN/M回繰り返す、
請求項1記載の発光素子駆動装置。
ただし、M、Nは、正の整数であり、M<Nである。 - 前記電圧印加部の個数をM、前記発光素子列の個数をNとすると、
前記制御部は、N個の発光素子列の全てをM個の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記同一の電圧印加部に接続されている発光素子列の中で最小の順方向電圧降下を有する発光素子列を別の電圧印加部に接続するように前記切替部を制御する処理をN/M回繰り返す、
請求項1記載の発光素子駆動装置。
ただし、M、Nは、正の整数であり、M<Nである。 - 前記制御部は、前記処理をN/M回繰り返した後、接続を切替える先の電圧印加部を変更して再度前記処理を繰り返す、
請求項5に記載の発光素子駆動装置。 - 前記制御部は、接続を切替える先の電圧印加部の変更をM-2回繰り返す、
請求項7に記載の発光素子駆動装置。 - 前記制御部は、前記処理をN/M回繰り返した後、接続を切替える先の電圧印加部を変更して再度前記処理を繰り返す、
請求項6に記載の発光素子駆動装置。 - 前記制御部は、接続を切替える先の電圧印加部の変更をM-2回繰り返す、
請求項9に記載の発光素子駆動装置。 - 前記制御部は、前記複数の発光素子列の全てを前記複数の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記同一の電圧印加部に接続されている発光素子列の中で最大の順方向電圧降下を有する発光素子列を別の電圧印加部に接続するとともに、前記同一の電圧印加部に接続されている発光素子列の中で最小の順方向電圧降下を有する発光素子列をさらに別の電圧印加部に接続するように前記切替部を制御する、
請求項1記載の発光素子駆動装置。 - 前記電圧印加部の個数をM、接続される前記発光素子列の個数をNとすると、
前記制御部は、N個の発光素子列の全てをM個の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記同一の電圧印加部に接続されている発光素子列の中で最大の順方向電圧降下を有する発光素子列を別の電圧印加部に接続するとともに前記同一の電圧印加部に接続されている発光素子列の中で最小の順方向電圧降下を有する発光素子列をさらに別の電圧印加部に接続するように前記切替部を制御する処理を、N/M回繰り返す、
請求項1記載の発光素子駆動装置。
ただし、M、Nは、正の整数であり、M<Nである。 - 前記制御部は、前記処理をN/M回繰り返した後、接続を切替える先の電圧印加部を変更して再度前記処理を繰り返す、
請求項12に記載の発光素子駆動装置。 - 前記制御部は、前記複数の発光素子列の全てを前記複数の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記複数の発光素子列の各々のカソード端に接続された複数の電流源にかかる電流源電圧と所定の閾値電圧とを比較して、前記閾値電圧を超える電流源電圧を有する発光素子列を別の電圧印加部に接続するように前記切替部を制御する、
請求項1記載の発光素子駆動装置。 - 前記制御部は、前記複数の発光素子列の全てを前記複数の電圧印加部のうち同一の電圧印加部に接続するように前記切替部を制御した後、前記複数の発光素子列の各々のカソード端に接続された複数の電流源にかかる電流源電圧と所定の閾値電圧とを比較して、前記閾値電圧未満の電流源電圧を有する発光素子列を別の電圧印加部に接続するように前記切替部を制御する、
請求項1記載の発光素子駆動装置。 - 前記制御部は、前記複数の発光素子列の全てを前記複数の電圧印加部の全てに均等に接続するように前記切替部を制御した後、駆動している全ての発光素子列の中で最大の順方向電圧降下を有する発光素子列を第1の電圧印加部に接続するように前記切替部を制御して当該最大の順方向電圧降下を有する発光素子列の駆動をオフするとともに、駆動している全ての発光素子列の中で最小の順方向電圧降下を有する発光素子列を第2の電圧印加部に接続するように前記切替部を制御して当該最小の順方向電圧降下を有する発光素子列の駆動をオフする、
請求項1記載の発光素子駆動装置。 - 前記電圧印加部の個数をM、前記発光素子列の個数をNとすると、
前記制御部は、N個の発光素子列の全てをM個の電圧印加部に均等に接続するように前記切替部を制御した後、駆動している全ての発光素子列の中で最大の順方向電圧降下を有する発光素子列を第1の電圧印加部に接続するように前記切替部を制御して当該最大の順方向電圧降下を有する発光素子列の駆動をオフするとともに、駆動している全ての発光素子列の中で最小の順方向電圧降下を有する発光素子列を第2の電圧印加部に接続するように前記切替部を制御して当該最小の順方向電圧降下を有する発光素子列の駆動をオフする処理を、N/M回繰り返す、
請求項1記載の発光素子駆動装置。
ただし、M、Nは、正の整数であり、M<Nである。 - 前記制御部は、前記処理をN/M回繰り返した後、接続を切替える先の電圧印加部を変更して再度前記処理を繰り返す、
請求項17に記載の発光素子駆動装置。 - 前記電圧印加部の個数がMであり、それぞれの電圧印加部を第1~第Mの電圧印加部とするとき、
前記制御部は、第Nの電圧印加部に接続されている発光素子列の中で最大の順方向電圧降下を有する発光素子列を第N-1の電圧印加部に接続するとともに、第Nの電圧印加部に接続されている発光素子列の中で最小の順方向電圧降下を有する発光素子列を第N+1の電圧印加部に接続するように前記切替部を制御する、
請求項1記載の発光素子駆動装置。
ただし、M、Nは、正の整数であり、M<Nである。 - 前記制御部は、M個の電圧印加部において、同一の発光素子列の接続の切り替えが繰り返された場合に、前記切替え部の制御を終了する、
請求項15に記載の発光素子駆動装置。 - 前記複数の電圧印加部はそれぞれ、
前記複数の発光素子列のカソード端に接続され、前記検出電圧を検出する検出回路と、
前記複数の発光素子列のアノード端に接続され、前記検出電圧に基づいて印加電圧を前記複数の発光素子列に印加する電圧変換回路と、を有する、
請求項1記載の発光素子駆動装置。 - 平面上に配置された複数の発光素子列と、
前記複数の発光素子列に接続される請求項1記載の発光素子駆動装置と、を備える、
面状照明装置。 - 請求項22記載の面状照明装置と、
前記面状照明装置からの照明光を背面から入射し、当該照明光を映像信号に応じて空間変調して映像を表示する液晶パネルと、を備える、
液晶表示装置。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP10732835.3A EP2448013A4 (en) | 2009-06-26 | 2010-03-11 | LIGHT EMITTING ELEMENT ATTACHING DEVICE, FLAT LIGHTING DEVICE, AND LIQUID CRYSTAL DISPLAY |
JP2010516721A JP4644315B2 (ja) | 2009-06-26 | 2010-03-11 | 発光素子駆動装置、面状照明装置および液晶表示装置 |
CN2010800010465A CN101990715B (zh) | 2009-06-26 | 2010-03-11 | 发光元件驱动装置、面状照明装置以及液晶显示装置 |
US12/769,399 US8081199B2 (en) | 2009-06-26 | 2010-04-28 | Light emitting element drive apparatus, planar illumination apparatus, and liquid crystal display apparatus |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2009151949 | 2009-06-26 | ||
JP2009-151949 | 2009-06-26 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/769,399 Continuation-In-Part US8081199B2 (en) | 2009-06-26 | 2010-04-28 | Light emitting element drive apparatus, planar illumination apparatus, and liquid crystal display apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2010150444A1 true WO2010150444A1 (ja) | 2010-12-29 |
Family
ID=43386234
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2010/001748 WO2010150444A1 (ja) | 2009-06-26 | 2010-03-11 | 発光素子駆動装置、面状照明装置および液晶表示装置 |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP2448013A4 (ja) |
JP (1) | JP4644315B2 (ja) |
CN (1) | CN101990715B (ja) |
WO (1) | WO2010150444A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016152272A1 (ja) * | 2015-03-20 | 2016-09-29 | ローム株式会社 | スイッチ駆動装置、発光装置、車両 |
WO2020044818A1 (ja) * | 2018-08-31 | 2020-03-05 | ソニーセミコンダクタソリューションズ株式会社 | 光源装置、調整方法、センシングモジュール |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN202203727U (zh) | 2011-08-16 | 2012-04-25 | 惠州元晖光电有限公司 | 具有光切换阵列的光引擎 |
CN102243854B (zh) | 2011-08-18 | 2013-10-16 | 深圳市华星光电技术有限公司 | 一种led背光驱动方法、液晶显示装置及led背光驱动电路 |
TWI559810B (zh) * | 2014-05-23 | 2016-11-21 | 友達光電股份有限公司 | 顯示裝置 |
US9502958B2 (en) * | 2015-01-30 | 2016-11-22 | Infineon Technologies Ag | Automatic short LED detection for light emitting diode (LED) array load |
TWI587738B (zh) * | 2016-05-02 | 2017-06-11 | 友達光電股份有限公司 | 偵測及校正裝置 |
CN107784968A (zh) * | 2017-11-06 | 2018-03-09 | 武汉华星光电技术有限公司 | 背光检测电路及相关产品 |
US10782335B2 (en) | 2017-11-06 | 2020-09-22 | Wuhan China Star Optoelectronics Technology Co., Ltd. | Backlight test circuit, backlight test method and backlight module using the same |
CN109410848B (zh) * | 2018-11-22 | 2020-09-29 | 昂宝电子(上海)有限公司 | Led背光驱动双控制器级联的系统和方法 |
JP7189804B2 (ja) * | 2019-02-26 | 2022-12-14 | ローム株式会社 | 発光素子駆動装置、発光素子駆動システム及び発光システム |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003332624A (ja) | 2002-05-07 | 2003-11-21 | Rohm Co Ltd | 発光素子駆動装置、及び発光素子を備えた電子機器 |
WO2006059437A1 (ja) * | 2004-11-30 | 2006-06-08 | Rohm Co., Ltd | スイッチングレギュレータの制御回路、電流駆動回路、発光装置および情報端末装置 |
JP2006187187A (ja) * | 2004-12-03 | 2006-07-13 | Rohm Co Ltd | 電源装置およびそれを用いた発光装置、電子機器 |
JP2008134288A (ja) * | 2006-11-27 | 2008-06-12 | Sharp Corp | Ledドライバ |
JP2008305978A (ja) * | 2007-06-07 | 2008-12-18 | New Japan Radio Co Ltd | 昇圧回路 |
JP2009151949A (ja) | 2007-12-18 | 2009-07-09 | Panasonic Electric Works Co Ltd | 直流コンセント |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3529718B2 (ja) * | 2000-10-03 | 2004-05-24 | ローム株式会社 | 携帯形電話機の発光装置およびその駆動ic |
JP2003332623A (ja) * | 2002-05-07 | 2003-11-21 | Rohm Co Ltd | 発光素子駆動装置及び、発光素子を備えた電子機器 |
KR100628718B1 (ko) * | 2005-02-26 | 2006-09-28 | 삼성전자주식회사 | Led구동장치 |
-
2010
- 2010-03-11 EP EP10732835.3A patent/EP2448013A4/en not_active Withdrawn
- 2010-03-11 CN CN2010800010465A patent/CN101990715B/zh not_active Expired - Fee Related
- 2010-03-11 WO PCT/JP2010/001748 patent/WO2010150444A1/ja active Application Filing
- 2010-03-11 JP JP2010516721A patent/JP4644315B2/ja not_active Expired - Fee Related
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003332624A (ja) | 2002-05-07 | 2003-11-21 | Rohm Co Ltd | 発光素子駆動装置、及び発光素子を備えた電子機器 |
WO2006059437A1 (ja) * | 2004-11-30 | 2006-06-08 | Rohm Co., Ltd | スイッチングレギュレータの制御回路、電流駆動回路、発光装置および情報端末装置 |
JP2006187187A (ja) * | 2004-12-03 | 2006-07-13 | Rohm Co Ltd | 電源装置およびそれを用いた発光装置、電子機器 |
JP2008134288A (ja) * | 2006-11-27 | 2008-06-12 | Sharp Corp | Ledドライバ |
JP2008305978A (ja) * | 2007-06-07 | 2008-12-18 | New Japan Radio Co Ltd | 昇圧回路 |
JP2009151949A (ja) | 2007-12-18 | 2009-07-09 | Panasonic Electric Works Co Ltd | 直流コンセント |
Non-Patent Citations (1)
Title |
---|
See also references of EP2448013A4 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016152272A1 (ja) * | 2015-03-20 | 2016-09-29 | ローム株式会社 | スイッチ駆動装置、発光装置、車両 |
JP2016175582A (ja) * | 2015-03-20 | 2016-10-06 | ローム株式会社 | スイッチ駆動装置、発光装置、車両 |
US10728980B2 (en) | 2015-03-20 | 2020-07-28 | Rohm Co., Ltd. | Switch driving device, light-emitting device, and vehicle |
WO2020044818A1 (ja) * | 2018-08-31 | 2020-03-05 | ソニーセミコンダクタソリューションズ株式会社 | 光源装置、調整方法、センシングモジュール |
Also Published As
Publication number | Publication date |
---|---|
CN101990715B (zh) | 2013-04-03 |
EP2448013A1 (en) | 2012-05-02 |
JPWO2010150444A1 (ja) | 2012-12-06 |
JP4644315B2 (ja) | 2011-03-02 |
CN101990715A (zh) | 2011-03-23 |
EP2448013A4 (en) | 2014-03-12 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP4644315B2 (ja) | 発光素子駆動装置、面状照明装置および液晶表示装置 | |
US8081199B2 (en) | Light emitting element drive apparatus, planar illumination apparatus, and liquid crystal display apparatus | |
JP4182930B2 (ja) | 表示装置及びバックライト装置 | |
US7714517B2 (en) | LED driver with current sink control and applications of the same | |
KR101196806B1 (ko) | 정전류구동장치, 백라이트 광원장치 및 컬러액정표시장치 | |
US8207933B2 (en) | Backlight unit, liquid crystal display device including the same, and method of driving liquid crystal display device | |
US8089218B2 (en) | Lighting devices | |
US9454931B2 (en) | Luminous display and method for controlling the same | |
KR20060045573A (ko) | 정전류 구동장치, 백라이트 광원장치 및 컬러 액정표시장치 | |
JP4720099B2 (ja) | 定電流駆動装置、バックライト光源装置及びカラー液晶表示装置 | |
KR20050011695A (ko) | 유기 발광 다이오드 디스플레이를 제어하는 방법 및 이방법을 적용하는 디스플레이 | |
JP2007165161A (ja) | Led照明装置、ledバックライト装置、及び画像表示装置 | |
US10939524B1 (en) | Driving LEDs in backlight for flat panel display | |
WO2012014588A1 (ja) | 発光装置、表示装置、発光素子駆動回路、および発光素子駆動方法 | |
KR20130030189A (ko) | 반도체 발광 소자를 적용한 조명 장치 | |
US20110043138A1 (en) | Light Emitting Device Capable of Dynamically Regulating Output Voltage and Related Control Method | |
KR101733202B1 (ko) | 발광다이오드 백라이트 유닛 및 그 구동방법 | |
JP2011108799A (ja) | 発光装置、並びに、当該発光装置を備えた照明装置及び表示装置 | |
CN215069166U (zh) | Led灯珠驱动电路和led显示装置 | |
TWI525366B (zh) | A power supply circuit and a display device using the same | |
US8076863B2 (en) | Back light module | |
JP2011113684A (ja) | 発光装置、並びに、当該発光装置を備えた照明装置及び表示装置 | |
US7068248B2 (en) | Column driver for OLED display | |
TWI834387B (zh) | 用於發光二極體面板的驅動電路及其發光二極體面板 | |
WO2023206333A1 (zh) | 显示驱动系统、方法和显示装置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 201080001046.5 Country of ref document: CN |
|
ENP | Entry into the national phase |
Ref document number: 2010516721 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2010732835 Country of ref document: EP |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 10732835 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |