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
  • G09G3/22—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 using controlled light sources
  • G09G3/30—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 using controlled light sources using electroluminescent panels
• • 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
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
  • G09G2300/0809—Several active elements per pixel in active matrix panels
• • 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
  • G09G2320/02—Improving the quality of display appearance
• • 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
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/029—Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel

Definitions

• the present invention relates to a method of determining conversion data of a display panel, and more particularly to a method of determining luminance conversion data for correcting dispersion of luminance in a TFT array display panel having a self light emitting element, and a display device using the same.
• the self light emitting element is a light emitting element that generates light according to the amount of current flowing through the element.
• a TFT array used for a display panel using such a self light emitting element needs to flow a much larger current than a TFT array for a liquid crystal panel which is a typical flat display panel in the past.
• a sufficient drive current can not often be obtained because the carrier mobility is low.
• the charge voltage in the gate insulating film causes the threshold voltage of the FET to change over time, and the variation in luminance of each pixel becomes large.
• a high driving current can be easily obtained because the carrier mobility is high, the aging is small, and a low temperature polysilicon film is often used.
• the current-voltage characteristics of each FET fluctuate by almost 10% depending on the crystal quality of the FET channel region.
• variations are likely to be widely dispersed between FETs within a short distance in the panel. That is, in a TFT array using a low temperature polysilicon film, the variation in luminance of each pixel at the time of manufacture is large.
• the secular change of the light emission characteristics of the light emitting element itself can not be ignored.
• the EL element uses an organic material, the degree of secular change is large depending on the operating conditions such as the operating temperature and the driving current. It is different. Such variations in light emission luminance cause defects in the display panel, such as image unevenness and color change.
• a pixel selection transistor 1 3 1 for selecting a pixel such as the EL display panel 1 0 8 in FIG. 1
• a drive transistor 1 for supplying a drive current according to the voltage of the capacitor 1 3 0 and the capacitor 1 3 0
• the pixel 1 1 7 of the TFT array of the display panel constituted by 8 and self light emitting elements (EL elements) 1 5 light emission when the capacitor 1 3 0 is charged and after it is completely discharged
• the capacitor of the measurement pixel must be completely discharged, that is, discharged to below the threshold voltage of the drive transistor, and then the next pixel must be measured.
• a considerable amount of time is required between pixel measurements.
• the steady state (the drive current becomes almost constant) from the start of application of the drive current. It takes time according to the time constant until it becomes. For this reason, if a large number of pixels such as a display panel are measured continuously, there is a problem that it takes a very long time.
• a display panel in which a plurality of pixels having a capacitor, a drive circuit for controlling current or voltage by the voltage of the capacitor, and a self-light emitting element driven by the drive circuit are arranged in a matrix.
• the first measurement step for determining the first drive current of the light emitting element of the display panel when there is not, the charging step for charging the capacitor of the measurement pixel to the ana- logue voltage, and the capacitor of the measurement pixel A second measurement step of measuring a second drive current of the light emitting element of the display panel when charging to the analog output voltage; A drive current calculation step of obtaining a drive current of the measurement pixel from a difference between the drive current and the second drive current, and a data calculation step of obtaining the conversion data based on the drive current.
• the drive current of the light emitting element of the display panel is measured prior to the measurement of the measurement pixel, and the difference between the drive current of the display panel and the light emission element when the measurement pixel is driven is calculated.
• the drive current of the pixel can be measured and the measurement can be performed. Can be measured at high speed.
• the measurement before driving the light emitting element is performed for each predetermined pixel, and the current value before driving of the unmeasured pixel is obtained from the measurement result to obtain higher speed measurement. In this case, although there is a variation in the characteristics of each pixel, it is not possible to obtain an accurate pre-drive current value depending on the capturing interval, but an absolute variation becomes smaller according to the discharge amount. The effects of variability can be ignored.
• the present invention provides a display panel having a TFT array and a self light emitting element, luminance signal generating means for converting luminance data to converted data to generate a luminance signal, and driving the self light emitting element by the luminance signal.
• a method of determining conversion data of a display panel comprising: driving means; and measuring means for measuring either or both of a driving current and a light emission luminance of a light emitting element of the TFT array, comprising: The method further comprises the steps of: driving a light emitting element; performing the measurement before the driving current of the measurement pixel reaches a saturation state; and determining the conversion data based on a result of the measurement.
• the above problem is solved by the method of determining conversion data of display panel. That is, the luminescence of the measurement pixel Even faster measurements can be made by performing measurement before the drive current or the drive current becomes saturated (the light emission luminance or the measurement current becomes a steady value when the device is driven).
• FIG. 1 is an overall view of a measuring apparatus which is an embodiment of the present invention.
• FIG. 2 is a diagram showing a measurement voice of the embodiment.
• FIG. 3 is a view showing a modification of the measurement point.
• FIG. 4 is an explanatory diagram of measured luminance.
• FIG. 5 is a diagram showing a control method of the luminance sensor.
• FIG. 6 is a diagram showing an equivalent circuit of the EL element.
• FIG. 7 is a diagram showing conversion data of the luminance signal generation circuit.
• FIG. 8 is a diagram showing a method of determining conversion data.
• an EL element is used as a self light emitting element in this embodiment, the present invention is not limited to an EL display panel, and another self light emitting element such as a display device using a light emitting diode is used. It can also be used for display panels.
• FIG. 1 shows a schematic configuration of a display device according to the present invention.
• the display device comprises a control unit 100 of a panel and an EL display panel 108.
• the control unit 100 is a pixel selection circuit 104 which is selection means connected to the shift register 1 0 9, 1 1 0 of the EL display panel 1 0 8, an external input of the luminance data and the EL display panel
• a luminance signal generation circuit 102 connected to the luminance signal line 1 120 of the 1 0 8 and having conversion data for each pixel, an ammeter 1 0 1 which is a measuring means, and an ammeter 1 0 1 are common
• a power source 103 which is a driving means connected to the line 1 1 9 and a data processor 1 0 5 which is connected to the ammeter 1 0 1 and has an information processing circuit and a memory and is a converted data determining means There is.
• the luminance data 10 corresponding to the small luminance and the luminance corresponding to the large luminance 2 5 for each pixel has a conversion table in which conversion data corresponding to 0 is stored.
• the EL display panel 108 includes a plurality of pixels 1 1 7 arranged in a matrix, data lines 1 1 1 and gate lines 1 1 6 for selecting pixels, data lines 1 1 1 and gate lines 1 It comprises shift registers 1 0 9 and 1 1 0 connected to 1 6 respectively.
• the pixel 1 1 7 is a pixel selection transistor Q 1 1 3 1 connected to the data line 1 1 1 and the gate line 1 1 6, and a capacitor C 1 connected to the pixel selection transistor 1 3 1 and the common line 1 1 9.
• a driving transistor Q 21 118 is connected to the driving element 130, the EL element 115, the capacitor 130, the pixel selection transistor 1 31, and the EL element 115.
• a constant current circuit is used as the drive circuit, but a voltage control circuit may be used.
• the pixel selection unit 104 outputs a pixel position signal according to an image signal (pixel position data and luminance data) input from the outside, and the shift registers 10 9 and 10 1 are pixels. Select the data line and gate line corresponding to the position. For example, if gate line 1 16 and data line 1 1 1 are selected, then pixel 1 1 7 at the intersection is selected.
• the luminance signal generator circuit 102 calculates the luminance signal by calculating the analog voltage corresponding to the input luminance data from the converted data (luminance data 10 and luminance data 250) corresponding to each pixel.
• the luminance signal of the luminance signal line 112 is supplied to the data line 111 selected by the pixel selection circuit 104.
• the pixel select transistor 1 31 is turned on, and the capacitor 130 is charged by the luminance signal on the data line 11.
• the pixel select transistor 1 3 1 is turned on.
• the voltage is maintained by turning off the switch.
• the voltage of the capacitor 130 controls the current of the drive transistor 118 which is a constant current circuit, and the drive current is applied to the EL element 115.
• the EL element 115 emits light with a light emission amount corresponding to the current amount of the drive current.
• the conversion values of luminance data 10 and luminance data 250 are used as the conversion data. It is possible to select which luminance data to use according to the numerical value range of the luminance data.
• linear interpolation since linear interpolation is used for interpolation, it corresponds to the lower limit value and the upper limit value of the region where the drive current (proportional to the capacitor applied voltage) has linear characteristics with respect to luminance data as shown in FIG. It is desirable to select the luminance data to be used, but by using nonlinear correction It is also possible to use regions with non-linear characteristics.
• a luminance signal of 0 V is applied to the luminance signal line 112, and the selection transistor 1 31 of each pixel is sequentially selected by the pixel selection circuit 104, and all the capacitors 1 of the EL display panel 10 8 3 Initialize 1).
• the current flowing to the ammeter 101 is recorded in the memory of the data processor 105.
• the measurement pixel 1 1 7 to be measured by the pixel selection circuit 1 0 4 is selected.
• an analog voltage corresponding to the luminance data 10 is applied from the luminance signal generation circuit 102 to the luminance signal line 112.
• the current flowing to the ammeter 101 is recorded in the memory of the data processor 105.
• the driving current I m in 1 of the measurement pixel 1 17 can be obtained.
• I mi ⁇ 1 is only 80% of the preset current value I min
• the luminance signal generation circuit 102 applies 0 V to the luminance signal line 112 to discharge the capacitor 130. Since it takes time to discharge the capacitor 130 completely until the voltage of the capacitor 130 reaches the threshold voltage of the driving transistor 118, it takes time before discharging to the threshold voltage. Turn off the pixel selection transistor 1 3 1 of, and perform the same measurement on the next measurement pixel. At this time, a predetermined current continues to flow in the drive transistor 118 of the pixel 117 due to the residual potential of the capacitor 130 of the pixel 117.
• the panel After the measurement of luminance data 10 for the pixels that need to be measured, initialize the panel. Then, measurement and conversion data determination on the luminance data 250 are performed in the same process. That is, as shown in FIG. 8, the driving current I ma 1 when the luminance signal corresponding to the luminance data 250 is applied to the capacitor 1 31 is determined and compared with a preset current value I min 1 Thus, the conversion value of the luminance data 250 of the luminance signal generation circuit 102 is corrected. Like this Thus, a pixel having the characteristic shown by the solid line in FIG. 8 can be corrected to a predetermined characteristic as shown by the broken line.
• FIG. 2 shows the measurement point of the ammeter 101 in the present embodiment.
• 401 ⁇ 402-403-404 is the current that flows to the ammeter 101 before the drive current is applied to the EL element of the measurement pixel
• 41 1 ⁇ 412 ⁇ 413 ⁇ 414 is the state of driving the EL element of the measurement pixel. Is the drive current in the state.
• the current flowing to the current meter 101 in the state before driving the EL element of the measurement pixel is It will increase gradually.
• the amount of increase in current is not strictly constant, but it is only necessary to maintain sufficient measurement and correction accuracy for measurement for correction of variations in luminance and drive current. There is no practical problem even if the amount of current increase is regarded as constant. Therefore, in the display device of this embodiment, the current before measurement is measured for every several pixels without actually measuring the current before measurement, and linear interpolation is performed from the latest measured drive current to measure the current It has a mode to obtain the current before measurement. When this mode is selected, for example, after the drive current value 401 is measured, the measurement of the drive current flowing to the display panel 108 before driving the EL element of the measurement pixel is not performed until the measurement of the drive current value 404.
• the drive current values 402 to 403 are interpolated and obtained from the measured values of the drive current values 401 to 404. In this manner, conversion data can be determined at higher speed by reducing the number of times of measurement of the current when the measurement pixel is not driven.
• the variation of the driving current can be corrected by appropriately performing measurement not only at the time of device manufacture but also at the time of use. Therefore, it is not necessary to provide a variation correction means such as providing a self correction circuit such as a current mirror circuit for each pixel 107 of the display panel 108, so that the device configuration can be simplified and an inexpensive device can be provided. .
• control unit 100 of this embodiment can be separated from the display device to be an independent measuring device.
• the luminance signal generation circuit 102, the power supply 103, and the pixel selection circuit 104 used for normal display are used as display devices, and the luminance signal generation circuit 102, the power supply 103, and the pixel selection circuit 104 used for determination of converted data are measured.
• Set in the bowl. Configuration of measuring instrument ⁇ Operation is the same as the correction mode described above. It is necessary to transmit the conversion data determined by force measurement to the luminance signal generation circuit built in the externally connected display device. Luminance signal of It is necessary to provide an output device in the raw circuit 102.
• FIG. 5 is a diagram showing an outline of a luminance measuring device added to the display device of this embodiment.
• a brightness detection circuit 1 connected to a brightness sensor 1 21 and a brightness sensor 1 2 1 scanning an EL display panel 1 0 8 and detecting brightness from an output signal from the sensor 1 2 1
• Sensor control circuit 1 2 3 that controls the operation of 2 2 and sensor 1 2 1 is attached.
• a light shielding means 120 is provided around the sensor 121 so that the sensor 121 can detect only light from pixels in the vicinity of the measurement pixel.
• the sensor control circuit 1 2 3 moves the sensor 1 2 1 onto the measurement pixel. Then, before driving the measurement pixel 117, the luminance is measured and stored in the memory of the data processor 105. Next, the EL element 115 of the measurement pixel 117 is driven with a driving current corresponding to the luminance data 10 and the luminance data 250, and the luminance at the time of driving is measured. Correct conversion data. Then, discharge the capacitor 130 of the measurement pixel 117 and measure the next pixel sequentially before completely discharging.
• the conversion data can be determined at high speed.
• the drive current ⁇ emission brightness after a predetermined time from the start of the current application is proportional to the drive current 'emission brightness in the steady state.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Control Of El Displays (AREA)
• Electroluminescent Light Sources (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)

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• 2003
  • 2003-09-05 JP JP2003314587A patent/JP2005084260A/ja active Pending
• 2004
  • 2004-04-23 TW TW093111441A patent/TW200511203A/zh unknown
  • 2004-09-02 CN CNA2004800231994A patent/CN1836269A/zh active Pending
  • 2004-09-02 KR KR1020067004530A patent/KR20060092208A/ko not_active Withdrawn
  • 2004-09-02 WO PCT/JP2004/013095 patent/WO2005024766A1/ja not_active Ceased
  • 2004-09-02 US US10/558,911 patent/US20060290618A1/en not_active Abandoned

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