JP2005284037A - Drive circuit for flat display device and flat display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a drive circuit which is suitably applied to a display device using organic EL elements, and the display device by this drive circuit by correcting variance in light emission characteristic and time changes that a drive circuit for a flat display device and the flat display device have. <P>SOLUTION: Source reference voltages VRT, VB to VG, and VRB used to generate reference voltages V1 to V64 for digital-to-analog conversion are generated according to source reference voltage setting data DV. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drive circuit for a flat display device and a flat display device, and can be applied to, for example, a display device using an organic EL (Electro Luminescence) element. The present invention generates an original reference voltage used for generating a reference voltage for digital-analog conversion in accordance with original reference voltage setting data so that variations in light emission characteristics can be corrected. A drive circuit suitable for application to a display device and a display device using the drive circuit are proposed.

  Conventionally, in a liquid crystal display device which is one of flat display devices, as disclosed in, for example, Japanese Patent Laid-Open No. 10-333648, gamma characteristics are switched by setting a reference voltage used for digital-analog conversion processing. Has been made.

  That is, as shown in FIG. 5, in the liquid crystal display device 1, each pixel (P) 3R, 3G, and 3B is formed by a liquid crystal cell, a switching element of the liquid crystal cell, and a storage capacitor, and the pixels 3R, 3G, and 3B are arranged in a matrix. The display part 2 is formed in a shape. In the liquid crystal display device 1, each pixel 3R, 3G, 3B of the display unit 2 is connected to a horizontal drive circuit 4 and a vertical drive circuit 5 via a signal line (column line) SIG and a gate line (row line) G, respectively. The pixels 3R, 3G, and 3B are sequentially selected by the vertical drive circuit 5, and the gradation of each pixel 3R, 3G, and 3B is set by the drive signal from the horizontal drive circuit 4, thereby displaying a desired image. Has been made. A color image can be displayed by sequentially and sequentially arranging pixels 3R, 3G, and 3B provided with red, green, and blue color filters, respectively.

  For this reason, the liquid crystal display device 1 inputs red, green, and blue image data DR, DG, and DB to be displayed from the device main body 6 to the controller 7 in parallel and synchronizes with the image data DR, DG, and DB. The gate line G of the display unit 2 is driven by the vertical drive circuit 5 according to the timing signal. The image data DR, DG, and DB are time-division multiplexed to correspond to the driving of the signal line SIG by the horizontal drive circuit 4 to generate one system of image data D1, and the horizontal drive circuit 4 is generated from the image data D1. To drive the signal line SIG.

  FIG. 6 is a block diagram showing the horizontal drive circuit 4 and the controller 7 in detail. The controller 7 supports the driving of the signal line SIG by the horizontal drive circuit 4 by sequentially storing and outputting the image data DR, DG, DB output from the apparatus main body 6 to the memory 10 under the control of the memory control circuit 9. As described above, the image data DR, DG, and DB are time-division multiplexed and output by one system so that the image data of the same color continues in line units in units of horizontal scanning periods. Specifically, in this example, for the red, green, and blue pixels 3R, 3G, and 3B, the horizontal drive circuit 4 sequentially drives the red pixel 3R, the green pixel 3G, and the blue pixel 3B in line units. Thus, as shown in FIG. 7B, the controller 7 sequentially repeats the red image data DR, the green image data DG, and the blue image data DB in units of lines. This image data D1 is output.

  Further, the controller 7 generates various timing signals synchronized with the image data D1 by the timing generator (TG) 11 and outputs them to the horizontal drive circuit 4 and the vertical drive circuit 5. Here, in this timing signal, for example, the clock CK of the image data D1 (FIG. 7A), the start pulse indicating the start and end timing of the image data DR, DG, DB of each color in the image data D1. ST (FIG. 7C), strobe pulse (FIG. 7D), and the like.

  In addition, the controller 7 generates the original reference voltages VRT, VB to VG, VRB, which are the generation references of the reference voltage used for the digital / analog conversion processing, by the original reference voltage generation circuit 12 and outputs the generated voltage to the horizontal drive circuit 4.

  The horizontal driving circuit 4 inputs the image data D1 output from the controller 7 to the shift register 13, and sequentially distributes and outputs the image data D1 to the signal line system of the display unit 2. The reference voltage generation circuit 14 generates reference voltages V1 to V64 corresponding to the gradations of the image data D1 from the original reference voltages VRT, VB to VG, and VRB input from the controller 7, and outputs them.

  Each of the digital / analog conversion circuits (D / A) 15A to 15N performs digital / analog conversion processing on the output data of the shift register 13, and in this example, in this example, the drive signals of the adjacent three signal lines SIG are time-division multiplexed. A drive signal is output. The digital / analog conversion circuits 15A to 15N select and output the reference voltages V1 to V64 generated by the reference voltage generation circuit 14 according to the output data of the shift register 13, thereby outputting the image data output from the shift register 13. Is converted from digital to analog.

  The amplifier circuits 16A to 16N amplify the output signals of the digital / analog conversion circuits 15A to 15N, respectively, and output the amplified signals to the display unit 2. The display unit 2 outputs the output signals of the amplifier circuits 16A to 16N in the selectors 17A to 17N. Are sequentially and cyclically output to the signal lines SIG related to the red, green, and blue pixels 3R, 3G, and 3B, respectively.

  In this way, the reference voltages V1 to V64 generated from the original reference voltages VRT, VB to VG, and VRB are selected to generate drive signals for the respective signal lines SIG, and FIG. It is a block diagram which shows the structure of the reference | standard voltage generation circuit 12 used for the production | generation of VB-VG, VRB, and the reference voltage generation circuit 14 used for the production | generation of reference voltage V1-V64.

  The original reference voltage generating circuit 12 is provided with a voltage dividing circuit 21 in which a predetermined number of resistors are connected in series, and the voltage dividing circuit 21 divides the reference voltage generating voltage VCOM to provide original reference voltages VRT, VB to VG, VRB. Is generated. As a result, the original reference voltage generation circuit 12 generates the original reference voltages VRT, VB to VG, and VRB by resistance voltage division and outputs them through the amplifier circuits 24A to 24H, respectively. In the case of a liquid crystal display device, the original reference voltage generation circuit 12 is configured so that the voltage applied to the voltage dividing circuit 21 can be switched by the selection circuit 22 and the inverting amplification circuit 23, whereby line inversion or frame inversion is performed. It is made to be able to cope with. Accordingly, FIG. 7F shows the potential of the signal line SIG in the case of line inversion.

  On the other hand, the reference voltage generation circuit 14 forms a resistor series circuit 26 by further connecting in series the voltage dividing circuits R1 to R7 in which a predetermined number of resistors having the same resistance value are connected in series. One end of a circuit 26, connection points of voltage dividing circuits R1 to R7 constituting the resistor series circuit 26, and the other end of the resistor series circuit 26 are respectively supplied to original reference voltages VRT, VB to VG through amplifier circuits 27A to 27H. VRB is input. As a result, the reference voltage generation circuit 14 further divides each potential difference by the original reference voltages VRT, VB to VG and VRB generated by the original reference voltage generation circuit 12 by the voltage dividing circuits R1 to R7, respectively. The reference voltages V1 to V64 are generated in the range of VRB.

  In this way, the reference voltages V1 to V64 are generated from the original reference voltages VRT, VB to VG, and VRB, so that the reference voltage generation circuit 14 has a predetermined number of resistors constituting the voltage dividing circuits R1 to R7. As a result, the original reference voltages VRT, VB to VG and VRB are divided to output a plurality of reference voltages V1 to V64 corresponding to the gradation of the image data D1.

  In the original reference voltage generation circuit 12, the resistors constituting the voltage dividing circuit 21 are displayed so that an image having a desired gamma characteristic is displayed by the reference voltages V1 to V64 corresponding to the gradation of the image data D1. Value is set. As a result, an example in which the voltage VCOM is set to 5 [V] can secure a desired gamma characteristic by polygonal line approximation by setting the original reference voltages VRT, VB to VG, and VRB, as indicated by reference numeral L1 in FIG. ing. In the original reference voltage generation circuit 12, the original reference voltages VRT, VB to VG, VRB output from the voltage dividing circuit 21 can be switched by changing the wiring pattern, whereby the characteristic indicated by reference numeral L1. As shown by reference numeral L2 in comparison with the above, for example, with the original reference voltages VRT and VRB that are potentials at both ends being fixed, the remaining original reference voltages VB to VG are varied within the range indicated by the arrows, and various gamma characteristics are obtained. Can be made variable.

  In this way, the gamma characteristic can be switched by the setting of the original reference voltage generation circuit 12 that generates the original reference voltages VRT, VB to VG, VRB. The controller 7 is formed by a control IC, whereas the horizontal drive circuit 4 is formed by a driver IC. As a result, in the conventional liquid crystal display device 1, it is possible to manufacture products with different gamma characteristics by changing only the control IC. It is made so that it can be shortened. Symbols CA to CH are stray capacitances between these ICs.

  By the way, in such a flat display device, there is a display device using an organic EL element. In the display unit of the display device using such an organic EL element, similarly to the display unit of the liquid crystal display device, the signal line SIG is driven. A method for setting the gradation of each organic EL element has been proposed. Accordingly, it is considered that the display device of the organic EL element according to such a method can be configured using a control IC or the like related to the liquid crystal display device.

However, in an organic EL element, the light emission characteristics differ from product to product for each color, and the light emission characteristics change over time. Specifically, it is necessary for the organic EL element to adjust the black level and the dynamic range for each color, for each product, and further corresponding to the change over time. It has been found that no adjustment is required for the gamma characteristic itself in the organic EL element. Thus, in the display device using the organic EL element, when the control IC shown in FIG. 8 is applied, the voltage across the voltage dividing circuit 21 is adjusted for each color, for each product, and further for the change with time. It becomes necessary to do. On the other hand, the original reference voltage generation circuit 12 shown in FIG. 8 can output only one type of reference voltages V1 to V64 with fixed values. Thus, depending on the drive circuit relating to the liquid crystal display device described above with reference to FIG. 5, it is not possible to cope with variations in light emission characteristics for each color and product and changes with time of the light emission characteristics. There is a problem that can not be configured.
JP-A-10-333648

  The present invention has been made in consideration of the above points. A flat display device drive circuit suitable for application to a display device using an organic EL element so as to correct variations in light emission characteristics and the like, and this drive circuit are used. It is intended to propose a flat display device.

  In order to solve such a problem, in the first aspect of the present invention, an original reference voltage generating circuit that generates a plurality of original reference voltages from a reference voltage generating voltage and a plurality of resistors are applied to a driving circuit of a flat display device. A reference voltage for connecting a plurality of series-connected voltage dividing circuits in series, inputting an original reference voltage between both ends and the voltage dividing circuit, and outputting a plurality of reference voltages by dividing voltages by the plurality of voltage dividing circuits. A generation circuit, a plurality of reference voltages are input, and a plurality of selection circuits that output drive signals are selected and output according to image data related to the corresponding signal lines, and an original that instructs setting of the original reference voltage An input circuit for inputting reference voltage setting data, and the original reference voltage generation circuit includes a plurality of digital-analog conversion circuits that respectively generate original reference voltages according to the original reference voltage setting data. To be in.

  According to a fifth aspect of the present invention, the horizontal drive circuit is applied to a flat display device, and the horizontal reference circuit generates a plurality of original reference voltages from a reference voltage generating power source and a plurality of resistors connected in series. A reference voltage generation circuit that further connects a plurality of divided voltage circuits in series, inputs an original reference voltage between both ends and the divided voltage circuits, and outputs a plurality of reference voltages by dividing voltages by the plurality of divided voltage circuits. And a plurality of selection circuits that output drive signals by inputting a plurality of reference voltages and selectively outputting them according to image data related to the corresponding signal lines. A plurality of digital-to-analog conversion circuits that respectively generate original reference voltages according to voltage setting data are provided.

  According to the configuration of the first aspect, an original reference voltage generating circuit that generates a plurality of original reference voltages from a reference voltage generating voltage and a voltage dividing circuit in which a plurality of resistors are connected in series are applied to a driving circuit of a flat display device. In addition, a plurality of reference connections are connected in series, an original reference voltage is input between both ends and the voltage dividing circuit, and a plurality of reference voltages are output by the divided voltages of the plurality of voltage dividing circuits, and a plurality of references A plurality of selection circuits for outputting drive signals and original reference voltage setting data for instructing the setting of the original reference voltage are input by inputting a voltage and selectively outputting it according to the image data related to the corresponding signal line. The original reference voltage generation circuit includes a plurality of digital-to-analog conversion circuits that respectively generate the original reference voltage according to the original reference voltage setting data. Various light emission characteristics by setting the data can be corrected. As a result, original reference voltage setting data can be set for each color to correct light emission characteristics that differ depending on the color, and original reference voltage setting data can be set for each product to correct light emission characteristics that vary between products. Furthermore, the original reference voltage setting data can be set in response to the change in the light emission characteristic, and the change in the light emission characteristic over time can be corrected, which makes it suitable for application to a display device using an organic EL element. A driving circuit for a flat display device can be provided.

  Accordingly, according to the configuration of claim 5, it is possible to provide a flat display device using such a drive circuit.

  According to the present invention, it is possible to provide a drive circuit suitable for application to a display device using an organic EL element, and a display device using this drive circuit, by making it possible to correct variations in light emission characteristics.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

(1) Configuration of Embodiment FIG. 2 is a block diagram showing PDA (Personal Digital Assistants) according to an embodiment of the present invention. In the apparatus main body 32, the PDA 31 displays various images on the display unit 34 by executing predetermined processing procedures with the controller 33, which is arithmetic processing means, in response to the operation of the operator. In FIG. 2, the same components as those in FIG. 6 described above are denoted by the corresponding reference numerals, and redundant description is omitted.

  Here, in this embodiment, the display unit 34 is a color image display panel in which pixels of organic EL elements are arranged in a matrix, and is lined by a vertical drive circuit (not shown) by gate lines connected to the pixels. A pixel is selected in units, and the gradation of each pixel is set according to the signal level of the signal line SIG.

  When the PDA 31 is shipped from the factory, the light emission characteristics of the respective colors are measured with respect to the display unit 34 of the organic EL element. Based on the measurement result, the original reference voltages VRT, VB to VG described above with reference to FIG. , The original reference voltage setting data DV instructing the setting of VRB is recorded for each color, and by using this original reference voltage setting data DV, the original reference voltages VRT, VB to VG, VRB are set, and the light emission characteristics of each color Variation and light emission characteristic variation between products can be corrected, whereby a display image can be displayed with correct white balance and color reproducibility.

  In this embodiment, among these original reference voltages VRT, VB to VG, VRB, the original reference voltage VRT having the highest voltage and the original reference voltage VRB having the lowest voltage are the levels of the black level and the white level, respectively. Accordingly, in the following description, these two original reference voltages VRT and VRB will be appropriately referred to as a black level original reference voltage VRT and a white level original reference voltage VRB, respectively. Correspondingly, the original reference voltage setting data DV corresponding to the original reference voltage VRT for black level and the original reference voltage VRB for white level is appropriately set to the original reference voltage setting data for black level, the original reference voltage for white level. These are referred to as setting data, and are indicated by symbols DVVRT and DVVRB, respectively, and correspondingly, original reference voltage setting data DV related to the original reference voltages VB to VG are indicated by symbols DVVB to DVVG, respectively. Accordingly, the memory 40 holds the black level original reference voltage setting data DVVRT, the white level original reference voltage setting data DVVRB, and other original reference voltage setting data DVVB to DVVG.

  Further, the PDA 31 can adjust a white balance, a black level, and a white level in the display unit 34 by executing a predetermined processing procedure by the controller 33 so as to be able to cope with a change in the light emission characteristics with the user's preference. The adjustment result is recorded and held in the memory 36, and the display on the display unit 34 is set based on the adjustment result. This PDA 31 uses the original reference voltage setting data DVVRT, DVVB to DVVG, DVVRB recorded in the memory 40 at the time of factory shipment, and the original reference voltage setting data DVVRT, DVVB to DVVG, DVVRB correction data D2 related to these adjustments. In addition, the difference data ΔDVVRT, ΔDVVB to ΔDVVG, and ΔDVVRB corresponding to the original reference voltage setting data DVVRT, DVVB to DVVG, DVVRB are recorded and held in the memory 36 for each color, and the correction recorded in the memory 36 is recorded. The data D2 is output to the controller 37 at a timing according to the processing of the controller 37, thereby recording and holding the adjustment result such as white balance adjustment, and further setting the display of the display unit 34 based on the adjustment result. Not to To have.

  The controller 37 is composed of an integrated circuit, and time-division multiplexes the image data DR, DG, and DB of each color output from the apparatus main body 32 in units of lines, and outputs image data D1 of one system. The original reference voltage setting data DV is corrected by the correction data D2 output from the controller 33 of the apparatus main body 32 and output to the horizontal drive circuit 45.

  That is, in the controller 37, the timing generator (TG) 48 generates and outputs various timing signals synchronized with the image data D1, DR to DB. The memory control circuit 49 controls the operation of the memory 50 based on this timing signal. The memory 50 sequentially stores and outputs the image data DR to RB output from the apparatus main body 32, thereby outputting the image data DR. , DG and DB are time-division multiplexed in line units to output image data D1.

  The memory control circuit 51 controls the operation of the memory 40 to read the original reference voltage setting data DV from the memory 40 and output it to the original reference voltage setting circuit 53 in the horizontal scanning cycle.

  The original reference voltage setting circuit 53 corrects and outputs the original reference voltage setting data DV output from the memory control circuit 51 with the correction data D2 output from the controller 33 of the apparatus main body 32. That is, as shown in FIG. 3, the original reference voltage setting circuit 53 inputs the original reference voltage setting data DV (DVVRT, DVVB to DVVG, DVVRB) input via the memory control circuit 51 to the adding circuit 53A. The correction data D2 (ΔDVVRT, ΔDVVB to ΔDVVG, ΔDVVRB) output from the controller 33 is added to correct the original reference voltage setting data DVVRT, DVVB to DVVG, DVVRB. The original reference voltage setting data DVVRT, DVVB, DVVG, DVVRB corrected in this way is input to the encoder 53B, where it is converted into serial data and output.

  In this series of processing, the original reference voltage setting circuit 53 outputs the original reference voltage setting data DV corresponding to the driving of the signal line SIG in the horizontal drive circuit 45. In this embodiment, however, the display unit 34 has a set of red, green, and blue pixels that are continuous in the horizontal direction, and the one set of pixels is driven in a time-sharing manner by a single drive signal, whereby The reference voltage setting circuit 53 is configured to switch and output the original reference voltage setting data DV for red, green, and blue image data DR, DG, and DB, respectively, during one horizontal scanning period.

  The horizontal drive circuit 45 is constituted by an integrated circuit separate from the controller 37, and each set of image data D1 output from the controller 37 is composed of red, green, and blue pixels that are continuously connected in the horizontal direction by the shift register 13. After the distribution, the digital / analog conversion processing is performed by the digital / analog conversion circuits 15A to 15N by the selector. Further, the drive signals resulting from the digital-analog conversion processing results are amplified by the amplifier circuits 16A to 16N and output to the display unit 34. The display unit 34 receives the output signals from the amplifier circuits 16A to 16N by the selectors 17A to 17N, respectively. Assign to line SIG.

  The horizontal drive circuit 45 applies the reference voltages V1 to V64 of the digital / analog conversion circuits 15A to 15N related to such a series of processes according to the original reference voltage setting data DV by the original reference voltage generation circuit 60 and the reference voltage generation circuit 59. Generate.

  FIG. 1 is a block diagram showing the original reference voltage generation circuit 60 and the reference voltage generation circuit 59. Here, the reference voltage generation circuit 59 is formed in the same manner as the reference voltage generation circuit 14 described above with reference to FIG. 8 except that the amplifier circuits 27A to 27H are omitted, and is output from the original reference voltage generation circuit 60. Reference voltages V1 to V64 are generated and output from the original reference voltages VRT, VB to VG, and VRB by resistance voltage division.

  The original reference voltage generation circuit 60 generates original reference voltages VRT, VB to VG, and VRB according to the original reference voltage setting data DV by the digital / analog conversion circuits (D / A) 61A to 61H, respectively.

  That is, the digital / analog conversion circuits 61A to 61H are configured in the same manner, and each of the voltage dividing circuits 62 divides the reference voltage generating voltage VCOM to generate a plurality of original reference voltage candidate voltages. Here, the voltage dividing circuit 62 is constituted by a series circuit of a plurality of resistors having the same resistance value, and the reference voltage generating voltage VCOM is divided and output with a resolution corresponding to the number of bits of the original reference voltage setting data DV. In this embodiment, the original reference voltage setting data DV is formed by 6 bits, and the reference voltage generating voltage VCOM is set to 5 [V], so that the voltage dividing circuit 62 is about 80 [mV] ( 64 candidate voltages having different voltages are output in units of ≈5 [V] / 64).

  The selector 63 selects and outputs the 64 types of candidate voltages output from the voltage dividing circuit 62 according to the original reference voltage setting data DV.

  The original reference voltage generation circuit 60 outputs the output voltages of the digital-analog conversion circuits 61A to 61H generated in this way as original reference voltages VRT, VB to VG, VRB via the amplification circuits 64A to 64H, The reference voltage generation circuit 59 inputs the original reference voltages VRT, VB to VG, and VRB to the resistor series circuit 26 and generates the reference voltages V1 to V64.

  The decoder 65 sequentially takes in the original reference voltage setting data DV by serial data output from the controller 37, distributes it to the digital / analog conversion circuits 61A to 61H at the timing corresponding to the switching of the contacts in the selectors 17A to 17N, and outputs it.

  FIG. 4 is a characteristic curve diagram showing an example of the gamma characteristic realized in this way. In this embodiment, for example, the gamma characteristic can be varied by setting the original reference voltage setting data DV as shown by the reference L2A with respect to the characteristic curve shown by the reference L1A. A desired image can be displayed. Also, by setting the black level original reference voltage setting data DVVRT and the white level original reference voltage setting data DVVRB, the black level and the white level are set for each color and for each product, and the variation of the light emission characteristics for each color and for each product, It is designed to be able to cope with a change in light emission characteristics over time. Further, two kinds of original reference voltage setting data DV are stored in the memory 40 so as to correspond to the line inversion, or the liquid crystal display panels indicated by the symbols L3 and L4 by switching the correction data D2 corresponding to the line inversion. The gamma characteristic according to the above can also be realized.

  Accordingly, in this embodiment, the original reference voltage generation circuit 60 constitutes an original reference voltage generation circuit that generates a plurality of original reference voltages VRT, VB to VG, VRB from the reference voltage generation voltage VCOM. 59, a plurality of voltage dividing circuits R1 to R7 each having a plurality of resistors connected in series are further connected in series, and original reference voltages VRT, VB to VG, VRB are respectively input between both ends and the voltage dividing circuits R1 to R7. A reference voltage generating circuit is configured to output a plurality of reference voltages V1 to V64 by the divided voltages by the plurality of voltage dividing circuits R1 to R7. The digital / analog conversion circuits 15A to 15N receive the plurality of reference voltages V1 to V64, and select and output according to image data related to the corresponding signal lines, thereby forming a plurality of selection circuits that output drive signals. The decoder 65 constitutes an input circuit for inputting original reference voltage setting data DV instructing setting of the original reference voltages VRT, VB to VG, VRB. In the original reference voltage generating circuit 60, the voltage dividing circuit 62 divides the reference voltage generating voltage VCOM to form a voltage dividing circuit for generating a plurality of original reference voltage candidate voltages. A selection circuit that outputs the original reference voltage is configured by inputting the candidate voltage and selectively outputting it according to the original reference voltage setting data DV (DVVRT, DVVB to DVVG, DVVRB). Further, the memory 50 and the memory control circuit 49 time-division-multiplex the image data related to the pixels of the same color and input to the horizontal drive circuit so that the image data related to the pixels of the same color are continuous in line units. The original reference voltage setting circuit 53 constitutes a data switching circuit that switches the original reference voltage setting data DV in response to the color switching of the time-division multiplexed image data. It is made like that.

(2) Operation of Embodiment In the above configuration, in this PDA 31 (FIG. 2), image data DR to DB for display is input from the apparatus main body 32 to the controller 37, and here, in line units via the memory 50. Time-division multiplexing processing is performed so that image data relating to the same color is continuous, and image data D 1 as a result of the processing is input to the horizontal drive circuit 45. In the horizontal drive circuit 45, the image data D1 is taken into the shift register 13, and the image data for the same color is input to the digital / analog conversion circuits 15A to 15N in parallel in units of lines. The digital-analog conversion circuits 15A to 15N convert the signals into drive signals, which are input to the selectors 17A to 17N via the amplifier circuits 16A to 16N, respectively. As a result, the image data D1 is a combination of the red, green, and blue pixels with respect to the pixels that are organic EL elements that are cyclically repeated in the horizontal direction in the order of red, green, and blue in the display unit 34. After the distribution, the signal is converted into a drive signal, and this drive signal is distributed to the signal lines SIG related to the red, green, and blue pixels by the selectors 17A to 17N, whereby the PDA 31 uses the image data DR to DB to The gradation is set and a desired image is displayed.

  Further, in the original reference voltage generating circuit 60 (FIG. 1), a plurality of original reference voltages VRT, VB to VG, VRB are generated from the reference voltage generating voltage VCOM, and a plurality of resistors formed by connecting a predetermined number of resistors in series. In a reference voltage generation circuit 59 by a resistor series circuit formed by further connecting voltage dividing circuits R1 to R7 in series, these original reference voltages VRT, VB to VG, VRB are divided by resistors to form reference voltages V1 to V64. In the digital / analog conversion circuits 15A to 15N, the image data D1 is subjected to digital / analog conversion processing by selection of the reference voltages V1 to V64 to generate a drive signal, which is set by the original reference voltages VRT, VB to VG and VRB. A drive signal is generated by a gamma characteristic based on broken line approximation, and an image is displayed.

  Thus, in the organic EL element, the light emission characteristics are different for each color and for each product, and further, the light emission characteristics are changed with time, so that the image data DR to DB are thus subjected to digital-analog conversion processing to drive signals. Thus, it is necessary to set the reference voltages V1 to V64 set in this way for each color and for each product, and to make corrections corresponding to changes with time.

  For this reason, the PDA 31 measures the light emission characteristics for each color and for each product, and based on the measurement results, the original reference voltages for instructing the settings of the original reference voltages VRT, VB to VG, VRB can be secured. Setting data DV is recorded and held in the memory 40. Further, correction data D2 for correcting the original reference voltage setting data DV is recorded and held in the memory 36 of the apparatus main body 32 in response to an adjustment operation by the user. In the PDA 31, after the original reference voltage setting data DV is corrected by the correction data D2 in the original reference voltage setting circuit 53, it is sequentially input to the horizontal drive circuit 45 corresponding to the time division multiplexing of the image data D1. The

  In the horizontal drive circuit 45, the original reference voltage setting data DV is divided into respective systems of original reference voltages VRT, VB to VG, VRB by the decoder 65, and these original reference voltage setting data DV are converted into digital / analog conversion circuits 61A to 61A. A digital analog conversion process is performed by 61H to generate original reference voltages VRT, VB to VG, VRB.

  Thus, in this embodiment, by setting the original reference voltage setting data DV, various light emission characteristics can be dealt with, and various display panels can be dealt with easily and quickly. That is, the dynamic range adjustment, black level adjustment, and gamma characteristics can be changed simply by changing the data, so that the development period can be greatly shortened compared to the conventional case, and the effort required for development can also be reduced.

  This also makes it possible to flexibly cope with variations in emission characteristics for each color and product, and changes in emission characteristics due to changes over time. Such variations in characteristics, deviations in white balance due to changes, and color reproducibility Deterioration can be effectively avoided and a high-quality display image can be provided.

  Further, in this way, the original reference voltages VRT, VB to VG, VRB are set by the original reference voltage setting data DV, and the original reference voltage setting corresponding to the time division multiplexing processing related to the transmission of the image data D1. By switching the data DV, it is possible to share one system of the original reference voltage generation circuit for processing the image data of each color, thereby effectively avoiding an increase in circuit scale and simplifying the overall configuration. It is made to be able to.

  In addition, the original reference voltage VRT, VB to VG, VRB is set by the original reference voltage setting data DV in this way, and the original reference voltage generating circuit that generates the original reference voltages VRT, VB to VG, VRB is used as the reference voltage. By providing an integrated circuit on the generation circuit side, it is possible to improve the accuracy of gamma setting and improve productivity.

  That is, consider the case where the original reference voltage generation circuit 12A is configured as shown in FIG. 10 and the original reference voltage generation circuit 12A and the reference voltage generation circuit 14 are formed by different integrated circuits. Here, the original reference voltage generation circuit 12A includes a red original reference voltages R-VRT, R-VB to R-VG, a voltage dividing circuit 21R that generates R-VRB, a green original reference voltage G-VRT, A voltage dividing circuit 21G for generating G-VB to G-VG and G-VRB, and a voltage dividing circuit 21B for generating blue original reference voltages B-VRT, B-VB to B-VG and B-VRB are provided, Three original reference voltages R-VRT, R-VB to R-VG, R-VRB, G-VRT, G-VB to G-VG and G-VRB output from these voltage dividing circuits 21R, 21G and 21B , B-VRT, B-VB to B-VG, and B-VRB are sequentially and cyclically selected by the selector 29 and output to the reference voltage generation circuit 14. Incidentally, even with such a configuration, although it is possible to cope with different light emission characteristics for each color, the configuration becomes complicated and the circuit scale increases and the power consumption increases because the voltage dividing circuit 21 is provided for each color. . In addition, a color shift occurs due to variations in the voltage dividing circuits 21R, 21G, and 21B. Furthermore, it goes without saying that it is not possible to cope with light emission characteristics that differ from product to product, and changes with time in light emission properties.

  As described above, when the original reference voltage generation circuit 12A and the reference voltage generation circuit 14 are formed by different integrated circuits, the static voltage related to the wiring pattern for outputting the original reference voltages VRT, VB to VG, VRB to the reference voltage generation circuit 14 is obtained. Since the capacitances CA to CH become several [pF] to several tens [pF], similarly to the configuration of the liquid crystal display device described above with reference to FIG. Amplifying circuits 24A to 24H and 27A to 27H are inevitably provided on the other side, thereby increasing the power consumption accordingly. In addition, since two amplifier circuits 24A to 24H and 27A to 27H are provided in the paths of the original reference voltages VRT, VB to VG, and VRB, variations in the original reference voltages VRT, VB to VG, and VRB due to the amplifier circuits are provided. Also grows.

  In addition, it is necessary to drive such a large load with electrostatic capacitances CA to CH by the amplifier circuits 24A to 24H and switch the original reference voltages VRT, VB to VG, VRB three times in one horizontal operation period. In these amplifier circuits 24A-24H and 27A-27H, it is necessary to enable high-speed operation as compared with the case of a liquid crystal display device, which further increases power consumption, and transistors related to control ICs and the like. Therefore, it is necessary to increase the chip area, and the circuit scale increases accordingly. In addition, when the chip area of the transistor is increased in this way, the variations of the amplifier circuits 24A to 24H and 27A to 27H are further increased, and the capacitances CA to CH are also varied. Even if the original reference voltages VRT, VB to VG, VRB are set by the reference voltage setting data DV, if the original reference voltage generation circuit and the reference voltage generation circuit are formed by separate integrated circuits, the practically sufficient accuracy As a result, the original reference voltages VRT, VB to VG, VRB cannot be supplied to the voltage dividing circuits R1 to R7. Specifically, in this embodiment, the original reference voltages VRT, VB to VG, VRB are generated with a resolution of 80 [mV], whereas the original reference voltage generation circuit and the reference voltage generation circuit are separately integrated. When formed by a circuit, the original reference voltages VRT, VB to VG and VRB input to the voltage dividing circuits R1 to R7 vary by several times of this resolution, which makes it difficult to put to practical use.

  Note that the operation speed of such an amplifier circuit can be determined by the settling time. Here, the settling time is such that the original reference voltages VRT, VB to VG, VRB are switched in this way until the signal level of the corresponding signal line SIG is stabilized at a constant signal level corresponding to the gradation of the image data D1. In this example, the sum of the settling time of the amplifier circuits 24A to 24H, the settling time of the amplifier circuits 27A to 27H, and the settling time of the amplifier circuits 16A to 16N, and these amplifier circuits 24A to 24H 27A to 27H and 16A to 16N, the capacitances CA to CH are large, so that the settling time is the longest in the amplifier circuits 24A to 24H.

  However, if the original reference voltage generation circuit is provided on the reference voltage generation circuit side and integrated as in this embodiment, the capacitances associated with the transmission paths of the original reference voltages VRT, VB to VG, VRB are reduced step by step. By doing so, the amplifier circuit can be omitted. Further, the remaining amplifier circuit without the amplifier circuit can be switched to the original reference voltages VRT, VB to VG, VRB without increasing the chip area. Sufficient accuracy can be ensured by setting the original reference voltages VRT, VB to VG, VRB by DV. Further, since the amplifier circuit can be omitted, the configuration can be simplified and power consumption can be reduced accordingly.

  In this way, the original reference voltages VRT, VB to VG, VRB are set by the original reference voltage setting data DV, so that the PDA 31 eventually outputs the original reference voltage setting data DV three times in one line to generate the gamma. The characteristics will be switched. As a result, even if the gamma characteristic is erroneously set due to noise mixing, for example, the erroneous gamma setting due to the influence of noise can be stopped in one line, and image quality deterioration due to noise can be stopped to the minimum.

(3) Advantages of the embodiment According to the above configuration, by generating the original reference voltage used for generating the reference voltage for digital-analog conversion in accordance with the original reference voltage setting data, variation in light emission characteristics, It is possible to provide a drive circuit suitable for application to a display device using an organic EL element so that the change can be corrected, and a display device using this drive circuit.

  At this time, the reference voltage generating voltage is divided to generate a plurality of original reference voltage candidate voltages, and the original reference voltage is generated by the selection output corresponding to the original reference voltage setting data of the plurality of candidate voltages. With this configuration, the original reference voltage can be generated with high accuracy.

  Also, by integrating the original reference voltage generation circuit and the reference voltage generation circuit together with other components into an integrated circuit, an amplifier circuit for providing the output of the original reference voltage is omitted, and compared with the conventional case. The gamma can be set with a practically sufficient accuracy by simplifying the configuration and further reducing the power consumption.

  Corresponding to the repetition of the pixels in the display unit, the image data is time-division multiplexed and transmitted so as to drive the display unit in units of lines so that the image data relating to the pixels of the same color is continuous. Corresponding to the switching of image data related to time-division multiplexing, the original reference voltage is switched by the original reference voltage setting data, so that the original reference voltage generation circuit and the reference voltage generation circuit are shared by each color, and different light emission by each color The characteristics can be corrected, and accordingly, a high-quality display image can be formed with a simple configuration.

  In addition, it is possible to cope with a change with time by generating original reference voltage setting data by correcting with correction data for correcting the change with time of the display unit.

  In the above-described embodiments, the case where the voltage dividing circuit is provided in each digital-analog conversion circuit of the original reference voltage generating circuit has been described. However, the present invention is not limited to this, and the voltage dividing circuit includes these voltage dividing circuits. The digital / analog conversion circuit may be shared.

  In the above-described embodiments, the case where the present invention is applied to a PDA has been described. However, the present invention is not limited to this and can be widely applied to various video devices.

  The present invention relates to a driving circuit for a flat display device and a flat display device, and can be applied to a display device using an organic EL element, for example.

1 is a block diagram illustrating an original reference voltage generation circuit and a reference voltage generation circuit of a PDA according to an embodiment of the present invention. It is a block diagram which shows PDA based on the Example of this invention. FIG. 2 is a block diagram illustrating an original reference voltage setting circuit in FIG. 1. It is a characteristic curve figure with which it uses for description of the gamma characteristic in PDA of FIG. It is a block diagram which shows the conventional liquid crystal display device. FIG. 6 is a block diagram showing a horizontal drive circuit in the liquid crystal display device of FIG. 5 together with a peripheral configuration. It is a time chart with which it uses for description of FIG. FIG. 7 is a block diagram showing an original reference voltage generation circuit and a reference voltage generation circuit in the horizontal drive circuit and controller of FIG. 6. FIG. 6 is a characteristic curve diagram for explaining gamma characteristics in the liquid crystal display device of FIG. 5. It is a block diagram which shows the example which provided the voltage dividing circuit for every color.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2, 34 ... Display part, 3R, 3G, 3B ... Pixel, 4, 45 ... Horizontal drive circuit, 6, 32 ... Main body, 7, 33, 37 ... Controller, 9, 49, 51 ... Memory control circuit, 10, 36, 40, 50 ... Memory, 12, 60 ... Original reference voltage generation circuit, 13 ... Shift register, 14, 59 ... Reference voltage generation circuit, 15A -15N, 61A-61H: Digital-analog conversion circuit, 16A-16N, 24A-24H, 27A-27H, 64A-64H ... Amplification circuit, 17A-17N, 63 ... Selector, 21, 62, R1-R7 ... ... voltage divider circuit, 26 ... resistor series circuit, 31 ... PDA, 53 ... original reference voltage setting circuit, 53B ... encoder, 65 ... decoder

Claims (8)

In a drive circuit of a flat display device for generating a drive signal by performing digital-analog conversion processing on image data, and driving a signal line of a display unit in which pixels are arranged in a matrix by the drive signal,
An original reference voltage generating circuit for generating a plurality of original reference voltages from a reference voltage generating voltage;
A plurality of voltage dividing circuits having a plurality of resistors connected in series are further connected in series, and the original reference voltage is input between both ends and the voltage dividing circuit, and a plurality of voltages are divided by the plurality of voltage dividing circuits. A reference voltage generation circuit for outputting a reference voltage;
A plurality of selection circuits for outputting the drive signal by inputting the plurality of reference voltages and selectively outputting the selected reference voltages according to the image data of the corresponding signal lines;
An input circuit for inputting original reference voltage setting data for instructing the setting of the original reference voltage, and the original reference voltage generation circuit,
A drive circuit for a flat display device, comprising: a plurality of digital-analog conversion circuits that respectively generate the original reference voltages in accordance with the original reference voltage setting data. The digital-to-analog converter circuit is
A voltage dividing circuit for the original reference voltage that divides the reference voltage generating voltage to generate a plurality of candidate voltages of the original reference voltage;
The flat display device according to claim 1, further comprising: a selection circuit that outputs the original reference voltage by inputting the plurality of candidate voltages and selectively outputting the candidate voltage according to original reference voltage setting data. Driving circuit. The driving circuit for a flat display device according to claim 1, wherein the original reference voltage generation circuit, the reference voltage generation circuit, the selection circuit, and the input circuit are integrated into an integrated circuit. The image data related to the pixels of each color is time-division multiplexed and input so that the image data related to the pixels of the same color is continuous in line units,
The original reference voltage generation circuit includes:
2. The driving circuit for a flat display device according to claim 1, wherein the original reference voltage is switched in response to the switching of the color associated with the image data input by time division multiplexing. 3. In a flat display device that displays an image based on image data,
A display unit in which pixels are arranged in a matrix,
A horizontal drive circuit for driving a signal line of the display unit by a drive signal,
The horizontal drive circuit includes:
An original reference voltage generation circuit for generating a plurality of original reference voltages from a power supply for generating a reference voltage;
A plurality of voltage dividing circuits having a plurality of resistors connected in series are further connected in series, and the original reference voltage is input between both ends and the voltage dividing circuit, and a plurality of voltages are divided by the plurality of voltage dividing circuits. A reference voltage generation circuit for outputting a reference voltage;
A plurality of selection circuits for inputting the plurality of reference voltages and selectively outputting according to the image data related to the corresponding signal lines, thereby outputting the drive signal;
The original reference voltage generation circuit includes:
A flat display device comprising: a plurality of digital-analog conversion circuits that respectively generate the original reference voltages in accordance with original reference voltage setting data. The digital-to-analog converter circuit is
A voltage dividing circuit for the original reference voltage that divides the reference voltage generating voltage to generate a plurality of candidate voltages of the original reference voltage;
The flat display device according to claim 5, further comprising: a selection circuit that outputs the original reference voltage by inputting the plurality of candidate voltages and selectively outputting the candidate voltage according to the original reference voltage setting data. . A time-division multiplexing circuit that time-division-multiplexes the image data relating to the pixels of each color and inputs them to the horizontal drive circuit so that the image data relating to the pixels of the same color is continuous in line units; A data switching circuit for switching the original reference voltage setting data in response to the switching of the colors related to the multiplexed image data,
The horizontal drive circuit includes:
The flat display device according to claim 5, further comprising: a selection circuit that switches output of the drive signal in response to switching of colors related to the image data. The data switching circuit is
The flat display device according to claim 7, wherein the original reference voltage setting data is generated by correction using correction data for correcting a change with time of the display unit.

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