US20070115685A1 - Flat lighting source, luminance correcting circuit, luminance correcting method and liquid crystal display - Google Patents

Flat lighting source, luminance correcting circuit, luminance correcting method and liquid crystal display Download PDF

Info

Publication number
US20070115685A1
US20070115685A1 US11/592,289 US59228906A US2007115685A1 US 20070115685 A1 US20070115685 A1 US 20070115685A1 US 59228906 A US59228906 A US 59228906A US 2007115685 A1 US2007115685 A1 US 2007115685A1
Authority
US
United States
Prior art keywords
luminance
light emitting
emitting devices
light
leds
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/592,289
Other languages
English (en)
Inventor
Yuji Kondo
Nobuaki Honbo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tianma Japan Ltd
Original Assignee
NEC LCD Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NEC LCD Technologies Ltd filed Critical NEC LCD Technologies Ltd
Assigned to NEC LCD TECHNOLOGIES, LTD. reassignment NEC LCD TECHNOLOGIES, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HONBO, NOBUAKI, KONDO, YUJI
Publication of US20070115685A1 publication Critical patent/US20070115685A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/342—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
    • G09G3/3426—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines the different display panel areas being distributed in two dimensions, e.g. matrix
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133603—Direct backlight with LEDs
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133612—Electrical details
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/04—Maintaining the quality of display appearance
    • G09G2320/041—Temperature compensation
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/0633—Adjustment of display parameters for control of overall brightness by amplitude modulation of the brightness of the illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/14—Detecting light within display terminals, e.g. using a single or a plurality of photosensors

Definitions

  • the present invention relates to a flat lighting source, luminance correcting circuit, and luminance correcting method to be used in the flat lighting source and liquid crystal display and particularly to the flat lighting source suitably used when illuminating light with uniform luminance has to be provided to an entire displaying region of a display panel, for example, in the case of a liquid crystal display device where illuminating light is provided by a backlight, and to the luminance correcting circuit and the luminance correcting method to be used in the flat lighting source.
  • a CCFL Cold Cathode Fluorescent Lamp
  • an LED Light Emitting Diode
  • the LED backlight ordinarily, a plurality of LEDs is connected in series and is driven at a constant current. Therefore, variations in current-luminance character-istic of each LED are reflected straightly as variations in luminance in a display region of a liquid crystal display device.
  • the “variations” represent secular changes in luminance characteristic to currents and temperatures.
  • FIG. 12 is a diagram showing electrical configurations of main components of an illuminating device disclosed in Patent Reference 1 [(Japanese Patent Application Laid-open No. 2004-221158, Abstract, FIGS. 1 and 4)].
  • the disclosed illuminating device includes an LED printed circuit board (PCB) 10 , a constant current source 20 , and a temperature compensating circuit 30 .
  • Alarge number of LED 11 , . . . , 11 are formed on the LED PCB 10 .
  • the constant current source 20 has a resistor 21 , a transistor 22 , an amplifying circuit 23 , and a comparison voltage generating circuit 24 .
  • the temperature compensating circuit 30 includes an FET (Field Effect Transistor) 31 , an LED 32 , an amplifying circuit 33 , and a photo-detecting device 34 .
  • FET Field Effect Transistor
  • the LED 32 having the same temperature characteristic as each of the LED 11 , . . . , 11 emits light which is converted by the photo-detecting device 34 into electrical signals.
  • the electrical signals are input into the comparison voltage generating circuit 24 .
  • Signals output from the comparison voltage generating circuit 24 are input into the amplifying circuit 23 and currents determined by a specified reference value through the transistor 22 based on signals output from the amplifying circuit 23 are fed to each of the LEDs 11 , . . . , 11 and changes in the temperature characteristic of each of the LEDs 11 , . . . , 11 are compensated for.
  • FIG. 14 is a diagram showing one example of configurations of a conventional LED backlight. Colors emitted from the LEDs 41 , . . . , 41 making up the LED backlight are a combination of R (Red), G(Green), and B(Blue) or white.
  • the LEDs 41 , . . . , 41 are mounted on the PCB 42 and every specified number of the LEDs 41 , . . . , 41 are connected serially. In this state, the LEDs emitting white color having the number corresponding to each level of supply power are connected serially and, when the LEDs emitting the white color can not be contained in a row, a plurality of rows each including the LEDs emitting the white color is arranged and connected in parallel among rows in some cases.
  • the LEDs emitting each of the R, G, and B when used, a specified number of LEDs in every color are serially connected. In this LED backlight, part of light components having given luminance emitted from the entire LEDs 41 , . . . , 41 is converted into electrical signals by the photo-detecting device 43 .
  • the photo-detecting device 43 by arranging the photo-detecting device 43 and the color filter 44 for each of R, G, and B, or by controlling the photo-detecting device 43 so that its light sensing characteristic has dependence on a wavelength, light having given luminance for each of R, G, and B is converted into an electrical signal.
  • a driving current and a driving voltage to be fed to the LEDs 41 , . . . , 41 are adjusted based on the electrical signal generated in proportion to the luminance and are controlled so that luminance of light received by the photo-detecting device 43 becomes constant.
  • the conventional LED backlight shown in FIG. 14 has a problem. That is, by keeping smooth track of a change in luminance of the light emitted from the LEDs 41 , . . . , 41 , the current and voltage to be fed to the LEDs 41 , . . . , 41 existing in the vicinity of the photo-detecting device 43 are well controlled, however, it is difficult to keep track of a change in luminance of the light emitted from the LEDs 41 , . . . , 41 existing at a location some distance from the photo-detecting device 43 .
  • Another problem is that, since radiation is difficult in a central portion of the PCB 42 , temperatures are likely to rise and, therefore, due to place-to-place variations of a temperature in areas surrounding the LEDs 41 , . . . , 41 and due to dependence of the LEDs 41 , . . . , 41 upon temperatures, it is made difficult to make uniform the distribution of luminance. Moreover, when variations occur in luminance of light emitted from the LEDs 41 , . . . , 41 due to secular changes in the LEDs 41 , . . . , 41 , only the luminance characteristic of the LED 41 existing in the vicinity of the photo-detecting device 43 is adjusted and variations still occur in the characteristic of luminance distribution of the entire LEDs 41 , .
  • Patent Reference 2 Japanese Patent Application Laid-open No. 2005-115372 (Abstract, FIG. 7A, 7B, 8B, FIG. 10)) in which photo-detecting devices are mounted not in one place but in a plurality of places.
  • FIG. 15 is a diagram showing configurations of LEDs used as the conventional backlight disclosed in the Patent Reference 2.
  • the disclosed backlight as shown in FIG. 15 , four rows of the LEDs 51 each row having 31 pieces are arranged on the PCB 50 and are connected in series.
  • FIG. 16 is a diagram showing another configurations of LEDs used as the conventional backlight disclosed in the Patent Reference 2.
  • a plurality of rows of LEDs each having three to seven LEDs connected serially to one another is arranged.
  • FIG. 17 is a cross-sectional view of the conventional backlight in which the LEDs 51 shown in FIG. 15 or FIG. 16 are mounted.
  • this backlight 52 as shown in FIG. 17 , each photo-detecting device 53 is mounted between the LEDs 51 and a diffusing body 54 and an LCD (Liquid Crystal Display) panel 55 are mounted in a direction in which light is emitted from each of the LEDs 51 .
  • LCD Liquid Crystal Display
  • FIG. 18 is a block diagram showing configurations of a correcting circuit to correct luminance characteristic of the LEDs 51 shown in FIG. 15 or FIG. 16 .
  • a signal “a” output from the photo-detecting device 53 is detected by a detector 61 and, based on a detected signal “b”, a luminance characteristic of the LEDs 51 is corrected by the controlling unit 62 .
  • the above conventional technologies have the following problems.
  • the illuminating device disclosed in the Patent Reference 1 and the backlight disclosed in the Patent Reference 2 it is impossible to detect and correct luminance of light emitted from an individual one out of a plurality of LEDs making up the LED light source.
  • a problem occurs in that the occurrence of changes in luminance due to secular change in the LEDs causes a change in luminance distribution in the liquid crystal panel.
  • Another problem is that, though total changes in luminance of light emitted from the LEDs caused by a change in temperatures can be corrected, a change in luminance of light emitted from an individual one of the LEDs cannot be corrected, as a result, causing a change in luminance distribution in the liquid crystal panel.
  • the illuminating device disclosed in the Patent Reference 1 has still another problem. That is, in the disclosed conventional illuminating device, when a change in temperature of the LEDs or a secular change in the LEDs are detected, luminance of light emitted from LEDs different from the LEDs actually used as the light source is referenced, however, there occurs rare coincidence of temperature, temperature characteristic, secular change characteristic (life characteristic) between the LEDs actually used and the LEDs used as the reference, which makes it difficult to make exact correction to these characteristics. Also, in the backlight disclosed in the Patent Reference 2, a plurality of LEDs is connected to one another in series, however, it is impossible to correct the characteristic of luminance such as luminance of light emitted from an individual LED out of the plurality of LEDs.
  • a flat lighting source having a plurality of light emitting devices so arranged as to form a planar surface and letting illuminating light come in a display region of a transmissive-type display panel from its rear, including:
  • a plurality of luminance correcting circuits each to set luminance of light to be emitted from each of the plurality of light emitting devices at a targeted value for every light emitting device and to detect an amount of deviation in luminance of light from the targeted value occurring when each of the plurality of light emitting devices is turned ON, and to make the luminance of light coincide with the targeted value, based on the detected amount of deviation.
  • a preferable mode is one wherein the luminance correcting circuit includes:
  • a plurality of photo-detecting devices so mounted as to correspond to each of the plurality of light emitting devices in a one-to-one relationship which receives light emitted from each of the plurality of light emitting device and generates a luminance detecting signal having a level corresponding to luminance of light emitted from each of the plurality of light emitting devices;
  • a plurality of driving/correcting circuits each being mounted so as to correspond to each of the plurality of light emitting devices in a one-to-one relationship, each of which supplies driving power to each of the plurality of light emitting devices and detects deviation in luminance of light emitted from each of the plurality of light emitting devices from a targeted value, based on a level of the luminance detecting signal, and corrects the driving power so that the deviation is compensated for.
  • a preferable mode is one wherein each of the plurality of light emitting devices is arranged, in a one-to-one relationship, in a vicinity of each of the plurality of photo-detecting devices.
  • a preferable mode is one wherein each of the plurality of light emitting devices and each of the plurality of photo-detecting devices are mounted in a same package.
  • a luminance correcting circuit to be used in a flat lighting source having a plurality of light emitting devices so arranged as to form a planar surface and letting illuminating light come in a display region of a transmissive-type display panel from its rear, wherein each of the luminance correcting circuits sets luminance of light to be emitted from each of the plurality of light emitting devices at a targeted value for every light emitting device and detects an amount of deviation in luminance of light from the targeted value occurring when each of the plurality of light emitting devices is turned ON, and makes the luminance of light coincide with the targeted value based on the detected amount of deviation.
  • a preferable mode is one that wherein includes:
  • a plurality of photo-detecting devices each being mounted so as to correspond to each of the plurality of light emitting devices in a one-to-one relationship and to receive light emitted from each of the plurality of light emitting devices;
  • a plurality of driving/correcting circuits each being mounted so as to correspond to each of the plurality of light emitting devices in a one-to-one relationship and to supply driving power to each of the plurality of light emitting devices and to detect deviation in luminance of light emitted from each of the plurality of light emitting devices from a targeted value, based on a level of the luminance detecting signal, and to correct the driving power so that the deviation is compensated for.
  • a flat lighting source including:
  • a plurality of luminance correcting circuits each of which is provided, in a one-to-one relationship with each of the plurality of the light emitting devices, to correct luminance of light emitted from the corresponding light emitting devices, based on a difference between a predetermined desirable luminance value and a detected luminance value obtained from the corresponding luminance detecting device, so as to maintain uniformity of the luminance of each of the light emitting devices.
  • a preferable mode is one wherein the light emitting devices each include a light emitting diode.
  • a liquid crystal display provided with a flat lighting source for backlighting
  • the flat lighting source including:
  • a plurality of luminance correcting circuits each of which is provided, in a one-to-one relationship with each of the plurality of the light emitting devices, to correct luminance of light emitted from the corresponding light emitting devices, based on a difference between a predetermined desirable luminance value and a detected luminance value obtained from the corresponding luminance detecting device, so as to maintain uniformity of the luminance of each of the light emitting devices.
  • a preferable mode is one wherein the light emitting devices each include a light emitting diode.
  • a plurality of luminance correcting circuits each of which sets luminance of light to be emitted from each of the light emitting devices at a specified targeted value and detects an amount of deviation of luminance of light emitted from each of the light emitting devices from the specified targeted value and makes the luminance of light emitted from each of the light emitting devices coincide with the specified targeted value based on the amount of deviation and, therefore, luminance of light emitted from each of the light emitting devices and brightness of an entire display region of a display panel can be made uniform.
  • Light having given luminance emitted from each of the light emitting devices is converted into a luminance detecting signal by each of the photo-detecting devices in a one-to-one relationship and the luminance detecting signal is fed back to each of the driving/correcting circuits and, therefore, variations and changes in luminance of light emitted from each of the light emitting devices can be automatically compensated for.
  • Light having given luminance emitted from each of the light emitting devices is fed back and a process of extracting only an amount of change in temperature for feeding back is not required and, therefore, each of the temperature correcting circuits for each of the light emitting devices is made unnecessary.
  • Each of the light emitting devices and each of the photo-detecting devices are mounted in the same package and in the vicinity of each other in a one-to-one relationship and, therefore, even if there are variations in luminance characteristic among the light emitting devices and the photo-detecting devices, luminance of light to be emitted from each of the light emitting devices can be made uniform by appropriately setting a targeted value of luminance.
  • Each of the light emitting devices is mounted so as to correspond to each of the photo-detecting devices in a one-to-one relationship and, therefore, whichever color light out of R, G, and B is emitted by each of the light emitting devices, changes in color balance can be compensated for without using a color filter.
  • the flat lighting source is used as a backlight for a transmissive-type liquid crystal panel, it is made possible to provide illuminating light with uniform luminance to an entire display region of the liquid crystal panel.
  • FIG. 1 is a block diagram showing electrical configurations of main components of a flat lighting source according to a first embodiment of the present invention
  • FIG. 2 is a circuit diagram showing one example of electrical configurations of LED driving/correcting circuits and driving/detecting circuits of FIG. 1 ;
  • FIG. 3 is a diagram showing one example of layout of the LEDs, photodiodes, set of LED driving/correcting circuits and driving/detecting circuits of FIG. 1 ;
  • FIG. 4 is a diagram showing another example of layout of the LEDs, photodiodes, LED driving/correcting circuits formed integrally with the driving/detecting circuits of FIG. 1 ;
  • FIG. 5 is a cross-sectional view showing layout of main components of the flat lighting source of the second embodiment of the present invention.
  • FIG. 6 is a cross-sectional view showing layout of main components of the flat lighting source of the third embodiment of the present invention.
  • FIG. 7 is a cross-sectional view showing layout of main components of the flat lighting source of the fourth embodiment of the present invention.
  • FIG. 8 is a cross-sectional view showing layout of main components of the flat lighting source of the fifth embodiment of the present invention.
  • FIG. 9 is a cross-sectional view showing layout of main components of the flat lighting source of the sixth embodiment of the present invention.
  • FIG. 10 is a cross-sectional view showing layout of main components of the flat lighting source of the seventh embodiment of the present invention.
  • FIG. 11 is a circuit diagram showing electrical configurations of luminance correcting circuits to be used in the flat lighting source of the eighth embodiment of the present invention.
  • FIG. 12 is a diagram showing electrical configurations of main components of an illuminating device disclosed in Patent Reference 1.
  • FIG. 13 is a diagram explaining operations of the illuminating device of FIG. 12 ;
  • FIG. 14 is a diagram showing one example of configurations of a conventional LED backlight.
  • FIG. 15 is a diagram showing configurations of LEDs used as a conventional backlight disclosed in Patent Reference 2;
  • FIG. 16 is a diagram showing another configurations of LEDs used as a conventional backlight disclosed in the Patent Reference 2;
  • FIG. 17 is a cross-sectional view of a backlight in which the LEDs shown in FIG. 15 or FIG. 16 are mounted.
  • FIG. 18 is a block diagram showing configurations of a correcting circuit to correct luminance characteristic of the LEDs shown in FIG. 15 or FIG. 16 .
  • a flat lighting source in which light having given luminance emitted from each LED used as a light emitting device is converted, in a one-to-one relationship, into a luminance detecting signal which is fed back to each luminance correcting circuit and luminance correcting circuits to be used in the flat lighting source are provided.
  • FIG. 1 is a block diagram showing electrical configurations of main components of a flat lighting source according to the first embodiment of the present invention.
  • the flat lighting source of the embodiment includes is used as a backlight of a transmissive-type liquid crystal panel mounted in a liquid crystal display panel and, as shown in FIG. 1 , LEDs 71 , photodiodes 72 as a photo-detecting device (luminance detecting device), LED driving/correcting circuits 73 , and driving/detecting circuits 74 .
  • LEDs 71 LEDs 71
  • photodiodes 72 as a photo-detecting device (luminance detecting device)
  • LED driving/correcting circuits 73 driving/detecting circuits 74 .
  • FIG. 1 only one LED 71 is shown, however, the flat lighting source is made up of a plurality of LEDs serving as a backlight and arranged in a manner to form a planar surface.
  • Each of the photodiodes 72 is mounted, in a one-to-one relationship, for every LED 71 and receives light emitted from each of the LEDs 71 and generates a luminance detecting voltage “a” having a level corresponding to the luminance of the received light.
  • Each of the driving/detecting circuits 74 is mounted, in a one-to-one relationship, for every photodiode 72 and supplies power to each of the photodiodes 72 and sends out the luminance detecting voltage “a” generated by each of the photodiodes 72 as a luminance detecting voltage V 2 to each of the LED driving/correcting circuits 73 .
  • Each of the LED driving/correcting circuits 73 is mounted, in a one-to-one relationship, for every LED 71 and supplies driving power “c” to each of the LEDs 71 and detects, based on the luminance detecting voltage V 2 fed from each of the driving/detecting circuits 74 , a deviation from each targeted value (value corresponding to a luminance setting voltage V 1 ) of luminance of light emitted from each of the LED and corrects the driving power “c” so as to compensate for the deviation from each of the targeted luminance value.
  • each of the LED driving/correcting circuits 73 increases a current to be fed, for example, as luminance of light emitted from each of the LED 71 decreases.
  • Each of the photodiodes 72 , LED driving/correcting circuits 73 , and driving/detecting circuits 74 make up each luminance correcting circuit.
  • Each of the luminance correcting circuits sets luminance of light to be emitted from each of the LEDs 71 at a targeted value and detects an amount of deviation from the targeted value of the luminance of light emitted from each of the LEDs 71 and then makes the luminance of light emitted from each of the LEDs 71 coincide with the targeted value, based on the amount of deviation from the targeted value.
  • FIG. 2 is a circuit diagram showing one example of electrical configurations of each of the LED driving/correcting circuits 73 and driving/detecting circuits 74 of FIG. 1 .
  • Each of the LED driving/correcting circuits 73 includes resistors 81 , 82 , 83 , and 84 , an operating amplifier 85 , resistors 86 , 87 , and 88 , an operating amplifier 89 , a resistor 90 , and an operating amplifier 91 , and a resistor 92 .
  • Each of the driving/detecting circuits 74 includes a constant current circuit 93 and an operating amplifier 94 .
  • FIG. 3 is a diagram showing one example of layout of each of the LEDs 71 , photodiodes 72 , set of LED driving/correcting circuits 73 and driving/detecting circuits 74 of FIG. 1 .
  • On the PCB 75 is arranged one each of the LEDs 71 , photodiodes 72 , set of LED driving/correcting circuits 73 and driving/detecting circuits 74 .
  • each of the LEDs 71 has various shapes, that is, each of the LEDs 71 may be sealed hermetically or may have a shape of a bare chip.
  • each of the LEDs 71 is mounted, in a one-to-one relationship, in the vicinity of each of the photodiodes 72 and each of the LED driving/correcting circuits 73 is integrally formed with each of the driving/detecting circuits 74 .
  • FIG. 4 is a diagram showing another example of layout of the LEDs 71 , photodiodes 72 , and LED driving/correcting circuits 73 formed integrally with the driving/detecting circuits 74 of FIG. 1 .
  • on the PCB 75 are arranged 20 sets of the LEDs 71 , photodiodes 72 , and LED driving/correcting circuits 73 formed integrally with driving/detecting circuits 74 .
  • any one of the photodiodes 72 in any one of the arrangement sets receives light from any one the LEDs 71 contained in an adjacent arrangement set, the photodiode 72 received light is affected by light emitted from any one the LEDs other than the LED 71 that originally has to provide light and, therefore, it is preferable that a structural measure to shield the photodiodes 72 from light emitted from other LEDs 71 is taken.
  • luminance of light emitted from each of the LEDs 71 is set at a specified targeted value and an amount of deviation from the targeted value occurring when each of the LEDs 71 is turned ON is detected and, based on the amount of the deviation, the luminance of light emitted from each of the LEDs 71 is corrected so as to coincide with the targeted value already set.
  • a current or voltage is supplied by each of the LED driving/correcting circuits 73 shown in FIG. 4 to each of the LEDs 71 .
  • either of constant current driving or constant voltage driving may be applied as a driving method.
  • Part of light components with given luminance emitted from each of the LEDs 71 is received by each of the photodiode 72 and is converted into electrical signals and a resistance value of each of the photodiodes 72 decreases in proportion to the luminance of received light accordingly. That is, if luminance of light emitted from each of the LEDs 71 increases, a resistance value of each of the photodiodes 72 decreases while the luminance of light emitted from each of the LEDs 71 decreases, the resistance value of each of the photodiodes 71 increases. The resistance value is detected by each of the driving/detecting circuits 74 and the resistance value is fed back to each of the LED driving/correcting circuits 73 . Each of the LED driving/correcting circuits 73 changes a driving current or driving voltage so that luminance of light emitted from each of the LEDs 71 becomes a level corresponding to a luminance setting voltage V 1 .
  • a luminance setting voltage V 1 is input to determine a driving current of each of the LEDs 71 and luminance of light emitted from each of the LEDs 71 is set according to the luminance setting voltage V 1 . Then, a current I 0 is fed from each of the LED driving/correcting circuit 73 to each of the LEDs 71 .
  • the luminance detecting voltage V 2 is the driving voltage of each of the photodiodes 72 that has already been fed through each of the operational amplifiers 94 serving as a voltage follower to each of the LED driving/correcting circuit 73 .
  • Each of the photodiodes 72 since it is driven by each constant current circuit 93 , has a resistance value corresponding to luminance of light emitted from each of the LEDs 71 . That is, when luminance of light emitted from each of the LEDs 71 decreases, a resistance value of each of the photodiodes 72 increases and a driving voltage of each of the photodiodes 72 increases, thus causing an increase in the luminance detecting voltage V 2 .
  • the voltage V 3 is increased to become a voltage being R 4 /R 3 times larger than the luminance detecting voltage V 2 according to the equation (2).
  • An increase in the voltage V 3 causes an increase in a driving current of each of the LEDs 71 and further an increase in the luminance of light emitted from each of the LEDs 71 . Therefore, by selecting the resistance values R 1 , R 2 , R 3 , and R 4 and a current Id of each of the constant current circuits 93 , a voltage is fed back from each of the photodiode 72 and, as a result, a change in luminance of light emitted from each of the LEDs 71 is compensated for.
  • each of the LEDs 71 is mounted, in a one-to-one relationship, in the vicinity of each of the photodiodes 72 , luminance of light emitted from each of the LEDs 71 is individually corrected and, therefore, even if there are variations in luminance characteristic among the LEDs 71 and among the photodiodes 72 , luminance of light emitted from each of the LEDs 71 is made uniform by appropriately setting the luminance setting voltage V 1 . Furthermore, each of the LEDs 71 corresponds to each of the photodiodes 72 and, therefore, whichever color out of R (Red), G (Green), and B (Blue) is emitted from each of the LEDs 71 , changes in color balance are compensated for without using a color filter.
  • FIG. 5 is a cross-sectional view showing layout of main components of the flat lighting source of the second embodiment of the present invention and the same reference numbers are assigned to components having the same function as those of the first embodiment shown in FIG. 4 .
  • each of the LED 71 , photodiodes 72 , LED driving/correcting circuits 73 , and driving/detecting circuits 74 is mounted in the same package 76 .
  • terminals or a like (not shown) to be used fro connection to external components are mounted.
  • each of the LEDs 71 is arranged, in a one-to-one relationship, in the vicinity of each of the photodiode 72 in the same package 76 and each of the LED driving/correcting circuits 73 and each of the driving/detecting circuits 74 are integrally formed and, therefore, the second embodiment has the same advantage as the first embodiment.
  • FIG. 6 is a cross-sectional view showing layout of main components of the flat lighting source of the third embodiment of the present invention and the same reference numbers are assigned to components having the same function as those of the second embodiment shown in FIG. 5 .
  • each of the photodiode 72 , each of the LED driving/correcting circuit 73 and each of the driving/detecting circuits 74 are integrally formed to operate as one IC (Integrated Circuit) 77 .
  • each of the LEDs 71 is arranged, in a one-to-one relationship, in the vicinity of the photodiode 72 and, therefore, the same advantage as obtained in the first embodiment can be achieved in the third embodiment as well.
  • FIG. 7 is a cross-sectional view showing layout of main components of the flat lighting source of the fourth embodiment of the present invention.
  • each of the LED driving/correcting circuit 73 and each of the driving/detecting circuit 74 are mounted outside the package 76 and on the PCB 75 together with the package 76 .
  • the PCB 75 is made of organic materials or inorganic materials.
  • each of the LEDs 71 is arranged, in a one-to-one relationship, in the vicinity of the photodiode 72 and, therefore, the same advantage as obtained in the first embodiment can be achieved.
  • FIG. 8 is a cross-sectional view showing layout of main components of the flat lighting source of the fifth embodiment of the present invention.
  • the same package 76 as shown in FIG. 8 is mounted on the PCB 75 and each correcting device 78 is newly mounted on the PCB 75 .
  • Each of the correcting devices 78 is made up of, for example, a variable resistor, a thick film printed resistance device to be trimmed by laser, a Zener zapping device consisting of a resistor and a Zener diode, a memory device that can write data corresponding to a targeted value of luminance of each of LEDs, or a like and is configured so as to provide a luminance setting voltage V 1 to each of the LED driving/correcting circuit 73 . Therefore, even if there are variations in luminance characteristic among the LEDs 71 and among the photodiodes 72 , luminance of light emitted from each of the LEDs 71 can be controlled to be uniform by appropriately setting the luminance setting voltage V 1 using each of the correcting devices 78 .
  • FIG. 9 is a cross-sectional view showing layout of main components of the flat lighting source of the sixth embodiment of the present invention and the same reference numbers are assigned to components having the same function as those of the fourth embodiment shown in FIG. 7 .
  • each of the correcting devices 78 shown in FIG. 8 is mounted on the PCB 75 shown in FIG. 7 . Therefore, even if there are variations in luminance characteristic among the LEDs 71 and among the photodiodes 72 , luminance of light emitted from each of the LEDs 71 can be controlled to be uniform by appropriately setting the luminance setting voltage V 1 using each of the correcting devices 78 .
  • FIG. 10 is a cross-sectional view showing layout of main components of the flat lighting source of the seventh embodiment of the present invention and the same reference numbers are assigned to components having the same function as those of the sixth embodiment shown in FIG. 9 .
  • each of the LED driving/correcting circuits 73 , driving/detecting circuits 74 , and correcting devices 78 are integrally formed to operate as one IC 79 .
  • luminance of light emitted from each of the LEDs 71 can be controlled to be uniform by appropriately setting the luminance setting voltage V 1 using each of the correcting devices 78 .
  • FIG. 11 is a circuit diagram showing electrical configurations of a luminance correcting circuit to be used in the flat lighting source of the eighth embodiment of the present invention and the same reference numbers are assigned to components having the same function as those of the first embodiment shown in FIG. 2 .
  • Each of the luminance correcting circuits of the eighth embodiment has, as shown in FIG. 11 , the LED driving/correcting circuit 73 A different from the LED driving/correcting circuit 73 shown in FIG. 2 .
  • Each of the LED driving/correcting circuits 73 A includes resistors 81 , 82 , 83 , and 84 , an operational amplifier 85 , an operational amplifier 95 , an n-channel type MOSFET (Metal Oxide Semiconductor Field Effect Transistor (nMOS)] 96 , and a variable resistor 97 .
  • nMOS Metal Oxide Semiconductor Field Effect Transistor
  • a current I 0 flowing through the LED 71 is shown by the following equation (3).
  • I 0 V 4 /RICC (3) where “RICC” denotes a resistance value of the variable resistor 97 .
  • Each of the luminance correcting circuit operates so that a voltage V 3 of a non-inverted input terminal (+) of the operational amplifier 95 is equal to a voltage of its inverted input terminal ( ⁇ ) and, as a result, the voltage V 3 is almost the same as the voltage V 4 .
  • the current I 0 flowing through each of the LEDs 71 is determined by the voltage V 4 and the resistance value RICC of the variable resistor 97 .
  • RICC resistance value
  • the operational amplifier 85 makes up an adding/subtracting circuit as in the first embodiment and, therefore, by changing a luminance setting voltage V 1 , the voltage V 3 changes.
  • the luminance correcting circuit shown in FIG. 2 or FIG. 11 may have any configuration so long as it has the same functions as the configurations shown in FIG. 2 or FIG. 11 have.
  • the present invention can be applied widely to cases where illuminating light with uniform luminance should be provided to an entire displaying region of a display panel, for example, of a liquid crystal display device in which illuminating light is supplied by a backlight.
US11/592,289 2005-11-22 2006-11-03 Flat lighting source, luminance correcting circuit, luminance correcting method and liquid crystal display Abandoned US20070115685A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2005337871A JP2007141799A (ja) 2005-11-22 2005-11-22 面照明光源、該面照明光源に用いられる輝度補正回路及び輝度補正方法
JP2005-337871 2005-11-22

Publications (1)

Publication Number Publication Date
US20070115685A1 true US20070115685A1 (en) 2007-05-24

Family

ID=38053258

Family Applications (1)

Application Number Title Priority Date Filing Date
US11/592,289 Abandoned US20070115685A1 (en) 2005-11-22 2006-11-03 Flat lighting source, luminance correcting circuit, luminance correcting method and liquid crystal display

Country Status (5)

Country Link
US (1) US20070115685A1 (ko)
JP (1) JP2007141799A (ko)
KR (1) KR100854192B1 (ko)
CN (1) CN1971367A (ko)
TW (1) TW200727047A (ko)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090040419A1 (en) * 2007-08-08 2009-02-12 Jin-Seok Lee Electron emission device for back light unit and liquid crystal display using the same
US20090116222A1 (en) * 2005-09-28 2009-05-07 Sharp Kabushiki Kaisha Backlight unit and liquid crystal display device
US20100007588A1 (en) * 2008-07-09 2010-01-14 Adaptive Micro Systems Llc System and method for led degradation and temperature compensation
US20100109562A1 (en) * 2008-11-06 2010-05-06 StarChips Technology Inc. Backlight module and light-emitting device thereof
US20100128051A1 (en) * 2007-04-23 2010-05-27 Sony Corporation Backlight device, backlight control method, and liquid crystal display device
US20100309236A1 (en) * 2009-06-03 2010-12-09 Woong-Ki Min Liquid crystal display
WO2011046552A1 (en) * 2009-10-14 2011-04-21 Hewlett-Packard Development Company, L.P. Stabilized light source having luminance feedback control
US10072830B2 (en) * 2016-05-06 2018-09-11 Hung Lin Uniform luminance light-emitting diode circuit board
US10217411B2 (en) 2014-07-18 2019-02-26 Boe Technology Group Co., Ltd. Display driving circuit, driving method thereof and display apparatus
US20190164493A1 (en) * 2017-11-24 2019-05-30 Boe Technology Group Co., Ltd. Pixel unit circuit, method for driving the same, and pixel circuit

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW200906221A (en) * 2007-07-19 2009-02-01 Aussmak Optoelectronic Corp Light emitting device and its calibrating and controlling method
CN100462780C (zh) * 2007-07-31 2009-02-18 友达光电股份有限公司 显示面板、包含其的光电装置及其驱动方法、制造方法
KR101450143B1 (ko) * 2007-10-25 2014-10-14 삼성디스플레이 주식회사 타이밍 컨트롤러, 이를 포함하는 액정 표시 장치 및 액정표시 장치의 구동 방법
JP5266878B2 (ja) * 2008-05-28 2013-08-21 岩崎電気株式会社 面照明装置
CN101697273B (zh) * 2009-10-29 2012-09-19 彩虹集团公司 使用led背光源的lcd亮度均匀性自动校正系统及校正方法
CN102136255B (zh) * 2010-01-27 2012-12-26 京东方科技集团股份有限公司 背光源的颜色补偿方法和装置
KR101013755B1 (ko) * 2010-02-02 2011-02-14 주식회사 삼광산전 정출력용 엘이디모듈 전원공급 컨버터
JP2012004190A (ja) * 2010-06-14 2012-01-05 Toshiba Corp Ｌｅｄ駆動装置
TWI455578B (zh) 2011-02-08 2014-10-01 Alpha Networks Inc 監控攝影機及其操作方法
KR101101250B1 (ko) * 2011-06-16 2012-01-04 버스텍 주식회사 발광다이오드 어레이의 특성 불균일을 개선한 발광다이오드 표시 장치 및 그에 따른 표시 제어 방법
CN105976767B (zh) * 2016-06-28 2019-06-21 凌云光技术集团有限责任公司 一种面光源亮度均匀性调节方法、装置及系统
CN109239980A (zh) * 2018-11-28 2019-01-18 厦门天马微电子有限公司 背光组件和显示装置
JP7303047B2 (ja) * 2019-06-27 2023-07-04 矢崎総業株式会社 発光装置及び色度ばらつき補正方法
CN113075525B (zh) * 2021-04-14 2022-03-22 东莞市谷麦光学科技有限公司 一种led分光站电压校正方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020047550A1 (en) * 2000-09-19 2002-04-25 Yoshifumi Tanada Self light emitting device and method of driving thereof
US6518962B2 (en) * 1997-03-12 2003-02-11 Seiko Epson Corporation Pixel circuit display apparatus and electronic apparatus equipped with current driving type light-emitting device
US20030234759A1 (en) * 2002-06-21 2003-12-25 Johan Bergquist Display circuit with optical sensor
US6720942B2 (en) * 2002-02-12 2004-04-13 Eastman Kodak Company Flat-panel light emitting pixel with luminance feedback
US20060038758A1 (en) * 2002-06-18 2006-02-23 Routley Paul R Display driver circuits

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7294816B2 (en) * 2003-12-19 2007-11-13 Avago Technologies Ecbu Ip (Singapore) Pte. Ltd. LED illumination system having an intensity monitoring system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6518962B2 (en) * 1997-03-12 2003-02-11 Seiko Epson Corporation Pixel circuit display apparatus and electronic apparatus equipped with current driving type light-emitting device
US20020047550A1 (en) * 2000-09-19 2002-04-25 Yoshifumi Tanada Self light emitting device and method of driving thereof
US6720942B2 (en) * 2002-02-12 2004-04-13 Eastman Kodak Company Flat-panel light emitting pixel with luminance feedback
US20060038758A1 (en) * 2002-06-18 2006-02-23 Routley Paul R Display driver circuits
US20030234759A1 (en) * 2002-06-21 2003-12-25 Johan Bergquist Display circuit with optical sensor

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7878698B2 (en) * 2005-09-28 2011-02-01 Sharp Kabushiki Kaisha Backlight unit and liquid crystal display device
US20090116222A1 (en) * 2005-09-28 2009-05-07 Sharp Kabushiki Kaisha Backlight unit and liquid crystal display device
US20100128051A1 (en) * 2007-04-23 2010-05-27 Sony Corporation Backlight device, backlight control method, and liquid crystal display device
US20090040419A1 (en) * 2007-08-08 2009-02-12 Jin-Seok Lee Electron emission device for back light unit and liquid crystal display using the same
US20100007588A1 (en) * 2008-07-09 2010-01-14 Adaptive Micro Systems Llc System and method for led degradation and temperature compensation
US20100109562A1 (en) * 2008-11-06 2010-05-06 StarChips Technology Inc. Backlight module and light-emitting device thereof
EP2184634A3 (en) * 2008-11-06 2010-06-02 Starchips Technology Inc. Backlight module and light-emitting device thereof
US20100309236A1 (en) * 2009-06-03 2010-12-09 Woong-Ki Min Liquid crystal display
US8493418B2 (en) * 2009-06-03 2013-07-23 Lg Display Co., Ltd. Liquid crystal display
WO2011046552A1 (en) * 2009-10-14 2011-04-21 Hewlett-Packard Development Company, L.P. Stabilized light source having luminance feedback control
US9024535B2 (en) 2009-10-14 2015-05-05 Hewlett-Packard Development Company, L.P. Stabilized light source having luminance feedback control
US10217411B2 (en) 2014-07-18 2019-02-26 Boe Technology Group Co., Ltd. Display driving circuit, driving method thereof and display apparatus
US10072830B2 (en) * 2016-05-06 2018-09-11 Hung Lin Uniform luminance light-emitting diode circuit board
US20190164493A1 (en) * 2017-11-24 2019-05-30 Boe Technology Group Co., Ltd. Pixel unit circuit, method for driving the same, and pixel circuit
US10867556B2 (en) * 2017-11-24 2020-12-15 Boe Technology Group Co., Ltd. Pixel unit circuit, method for driving the same, and pixel circuit

Also Published As

Publication number Publication date
KR100854192B1 (ko) 2008-08-26
JP2007141799A (ja) 2007-06-07
TW200727047A (en) 2007-07-16
KR20070054101A (ko) 2007-05-28
CN1971367A (zh) 2007-05-30

Similar Documents

Publication Publication Date Title
US20070115685A1 (en) Flat lighting source, luminance correcting circuit, luminance correcting method and liquid crystal display
US7872621B2 (en) Color LED driver
US7990360B2 (en) Backlight assembly and display device having the same
KR101010555B1 (ko) 조명 장치에서의 사용을 위한 광원 유닛
EP1619656B1 (en) Display unit and backlight unit
US8111371B2 (en) Illumination device and liquid crystal display device
US10078985B2 (en) Liquid crystal display
KR101204865B1 (ko) 백라이트의 구동 장치, 백라이트 및 이를 구비한액정표시장치 및 백라이트 구동의 방법
US9142157B2 (en) Methods for enhancing longevity in electronic device displays
US7173384B2 (en) Illumination device and control method
US20080284714A1 (en) Control circuit of area control driving circuit for led light source and controlling method thereof
US20080074382A1 (en) Display device, control method thereof, and backlight unit used therefor
US20100053136A1 (en) Gradation voltage correction system and display device using the same
US20100253613A1 (en) Led backlight and electronic control
KR20020087357A (ko) 활성 매트릭스 ｏｌｅｄ 플랫 패널 디스플레이
US20090201669A1 (en) Backlight device, and display apparatus using the same
US20100188024A1 (en) Method of calibrating a lighting system, and lighting system
KR20090094143A (ko) 전용 컬러 조절부를 가진 ｌｅｄ 모듈 및 대응 방법
KR101265102B1 (ko) 백라이트 유닛과 그 구동방법
KR101511128B1 (ko) 발광 다이오드의 구동방법, 이를 수행하기 위한 백라이트 어셈블리 및 이를 갖는 표시장치
JP7043277B2 (ja) 光源モジュール及びバックライト装置
KR20090078525A (ko) 엘이디 백라이트 유니트 드라이버 전류편차 보상을 위한전류측정장치
KR20110066734A (ko) 백라이트 유닛
CN116110347A (zh) 显示装置及电子设备

Legal Events

Date Code Title Description
AS Assignment

Owner name: NEC LCD TECHNOLOGIES, LTD., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KONDO, YUJI;HONBO, NOBUAKI;REEL/FRAME:018511/0550

Effective date: 20061017

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION