JP4790641B2 - γ characteristic inspection method - Google Patents

Description

  The present invention relates to a γ characteristic inspection method for inspecting whether or not a γ characteristic of a display device is appropriate.

  A display panel included in a display device capable of color display includes a display element that displays R (red) in a single color, a display element that displays G (green) in a single color, and a display element that displays B (blue) in a single color. Has been placed. Hereinafter, these three types of display elements are referred to as an R display element, a G display element, and a B display element, respectively. These three types of display elements are arranged in order within one line of the display panel, and a combination of the R display element, the G display element, and the B display element forms one dot. FIG. 15 is an explanatory diagram showing one dot. As shown in FIG. 15, the combination of the R display element 52, the G display element 53, and the B display element 54 becomes one dot 51. The display panel is provided with dots 51 shown in FIG. 15 in a matrix. In addition, a dot may be called a pixel or a pixel. And each display element 52-54 in a dot may be called a sub pixel.

By selecting the gradations of the display elements 52 to 54 included in one dot 51, the color of the dot 51 can be controlled. For example, it is assumed that the number of gradation types (number of gradations) that each of the display elements 52 to 54 can take is 256. In this case, 256 ³ types (about 16.77 million types) of colors can be displayed with one dot. A value indicating each gradation is referred to as a gradation value. The maximum gradation value is referred to as the maximum gradation value, and the minimum gradation value is referred to as the minimum gradation value.

  When the dots are white, black, or an intermediate color between white and black, the gradation values of the R display element 52, the G display element 53, and the B display element 54 may be set equal. For example, if the gradation values of the R display element 52, the G display element 53, and the B display element 54 are all 0, the dots 51 are black. If the gradation values of the R display element 52, the G display element 53, and the B display element 54 are all 255, the dot 51 is white. Further, if the gradation values of the R display element 52, the G display element 53, and the B display element 54 are all made equal and the gradation value is set to any one of 1 to 254, the dot 51 becomes an intermediate color (gray). As described above, when the number of gradations of each of the display elements 52 to 54 is 256, it is possible to display 256 gradations in gray scale. Gray scale is to display an image in white, black, and intermediate colors.

  In the following description, a case where the display device is a liquid crystal display device including a liquid crystal display panel will be described as an example. When performing gray scale display on a liquid crystal display device, when the minimum luminance (brightness during black display) is 0 and the maximum luminance (brightness during white display) is 1, the relative luminance of the dots of the liquid crystal display device is This is not proportional to the gradation value indicated by the image data. The relative luminance is a relative luminance with respect to the maximum luminance (that is, the luminance at the time of white display) corresponding to the maximum gradation value of the gray scale. When the relative luminance is y, the grayscale gradation value is n, the relative luminance y is represented on the vertical axis, and the gradation value n is represented on the horizontal axis, the relationship between the relative luminance y and the gradation value n is shown in FIG. As shown in FIG. Such a characteristic is called a γ characteristic.

  In the case of a liquid crystal display device, the relative luminance y is represented by the following formula 1, and the value of γ (referred to as γ value) in formula 1 is preferably a predetermined value (for example, 2.2). The

y = (n / maximum gradation value) ^γ (Formula 1)

  When the number of gradations is X, the gradation value is any value from 0 to X-1, and the maximum gradation value is X-1. Here, a case where the gray scale gradation number X is 256 and the gray scale gradation value is 0 to 255 will be described as an example. In this case, the maximum gradation value in Equation 1 is 255.

  An inspection for inspecting whether or not the γ characteristic of the display device is an appropriate γ characteristic is called a γ characteristic inspection. In the conventional γ characteristic inspection, some gradation values are sampled from all gradation values (for example, 0 to 255) of the gray scale, the luminance is measured for each gradation value, and the gradation value and It was inspected whether or not the relationship with luminance matched the preferable γ characteristic.

  Patent Document 1 describes a method for performing γ adjustment with high accuracy without using a measuring instrument. In the method described in Patent Document 1, two types of comb-shaped figures having different luminances are arranged in a vertical stripe shape, and the γ correction value is calibrated so as to be adjacent to the upper side of the two types of figures. An image in which the graphic to be calibrated is arranged is displayed, and γ adjustment is performed so that the luminance recognized by the two types of comb-shaped graphic is equal to the luminance of the graphic to be calibrated. Moreover, in the method described in Patent Document 1, after determining the white balance by changing the luminance of R (red), G (green), and B (blue), one color for each of R, G, B Perform gamma adjustment.

JP 2004-15471 A

  When the γ characteristic inspection is performed by measuring the luminance for each gradation value, there is a problem that it takes an inspection time to measure the luminance for each gradation value. In addition, an apparatus and a place for measuring the luminance are required, and the inspection cannot be easily performed.

  In the γ adjustment method described in Patent Document 1, γ adjustment can be performed without using a measuring instrument. However, in Patent Document 1, it is necessary to visually check the brightness for each of R, G, and B colors. If the R, G, and B colors are visually confirmed at a time by the method described in Patent Document 1, fine stripes appear in a figure in which two figures with different luminance are arranged in a vertical stripe shape. It becomes easy to be visually recognized.

  In FIG. 17, in a region where two figures having different luminances are arranged in a vertical stripe shape, one column 61 has the maximum grayscale luminance (gradation value n = 255), and another column 62 adjacent to the column 61. Indicates a state where the minimum luminance of gray scale (tone value n = 0) is set. Note that FIG. 17 shows an area for four dots. In the method described in Patent Document 1, when it is attempted to check each of the R, G, and B colors at once, the stripe-like columns are alternately placed in the same state as the columns 61 and 62 shown in FIG. To control. At this time, the dots arranged in the row direction are in the same state, and fine stripes are easily visually recognized in an area where two figures having different luminances are arranged in a vertical stripe shape. Then, the appearance is different between an area where such fine stripes are visually recognized (an area where a figure is arranged in a vertical stripe shape) and an area of the figure to be calibrated. As a result, it becomes difficult to compare the luminance of the region in which the graphic is arranged in a vertical stripe shape with the luminance of the region of the graphic to be calibrated.

  The same problem occurs even when two figures having different luminance are arranged in a horizontal stripe shape. FIG. 18 shows that in a region where two figures having different luminances are arranged in a horizontal stripe, one row 63 is set to the maximum grayscale luminance, and another row 64 adjacent to the row 63 is set to the minimum grayscale luminance. Indicates the state. FIG. 18 also shows an area for four dots. In order to check the luminance of each color of R, G, and B at once, if the stripe-like rows are in the same state as the rows 63 and 64 shown in FIG. 18, the states of the dots arranged in the row direction are the same. In a region where two figures are arranged in a horizontal stripe shape, fine stripes are easily visible. As a result, it becomes difficult to compare the luminance of the region where the graphic is arranged in a horizontal stripe shape with the luminance of the region of the graphic to be calibrated.

  Therefore, the present invention has an object to provide a γ characteristic inspection method that does not require comparison of luminance in two regions for each of R, G, and B colors and that can be easily performed. To do.

The γ characteristic inspection method of the present invention combines an R display element that is a display element that displays red, a G display element that is a display element that displays green, and a B display element that is a display element that displays blue. A method for inspecting γ characteristics of a display device in which dots are arranged in a matrix, wherein only one display element among R display elements, G display elements, and B display elements corresponds to the maximum gradation value within one dot. As a display state, the other two display elements are set to a display state corresponding to the minimum gradation value, and the two display elements among the R display element, the G display element, and the B display element are set to the maximum floor within one dot. A first image in which the remaining one display element is displayed according to the minimum gradation value as a display state according to the tone value, arranged in a checkered pattern, an R display element within each dot, G The display element and the B display element are half of the maximum luminance. Whether the second image in the display state corresponding to the gradation value for realizing the luminance is displayed on the display device adjacent to the second image, and the boundary is visually recognized between the first image and the second image No, and after determining that the boundary is not visually recognized between the first image and the second image, one of the R display element, the G display element, and the B display element within one dot. A display in which only one display element is in a display state corresponding to the maximum gradation value, and the other two display elements are in a display state in accordance with the gradation value for realizing a luminance of ½ of the maximum luminance, and 1 dot The two display elements of the R display element, the G display element, and the B display element are displayed in a display state corresponding to the maximum gradation value, and the remaining one display element realizes a luminance that is ½ of the maximum luminance. A third image arranged in a checkered pattern with a display state corresponding to the gradation value for The R display element, the G display element, and the B display element in the display device adjacent to the fourth image in a display state corresponding to a gradation value for realizing a luminance of 3/4 of the maximum luminance. It is displayed and it is judged visually whether a boundary is visually recognized between the 3rd picture and the 4th picture .

  When the boundary is visually recognized between the third image and the fourth image, a method of changing the setting of the driving device of the display device so that the boundary is not visually recognized may be used.

An inspection image including the adjacent first image and second image and the adjacent third image and fourth image may be displayed on the display device.
The γ characteristic inspection method of the present invention includes an R display element that is a display element that displays red, a G display element that is a display element that displays green, and a B display element that is a display element that displays blue. A gamma characteristic inspection method for a display device in which the combined dots are arranged in a matrix, and only one display element among the R display element, the G display element, and the B display element is set to the maximum gradation value within one dot. As a corresponding display state, the other two display elements are displayed in a display state corresponding to the minimum gradation value, and the two display elements among the R display element, the G display element, and the B display element are displayed within one dot. A first image in which the remaining one display element is displayed according to the minimum gradation value as a display state corresponding to the maximum gradation value, arranged in a checkered pattern, and the R display element in each dot , G display element, and B display element with a maximum luminance of 1 The second image having a display state corresponding to the gradation value for realizing the luminance of / 2 is displayed adjacent to the display device, and the boundary is visually recognized between the first image and the second image. It is determined visually whether or not the boundary is not visually recognized between the first image and the second image, and the R display element, the G display element, and the B display element are within one dot. A display state in which only one of the display elements is in a display state corresponding to a gradation value for realizing a luminance of ½ of the maximum luminance, and a display state in which the other two display elements are in a display state according to the minimum gradation value; The remaining one of the two display elements of the R display element, the G display element, and the B display element within one dot is displayed as a display state corresponding to a gradation value for realizing a luminance of ½ of the maximum luminance. A fifth image in which two display elements are arranged in a checkered pattern with a display state corresponding to the minimum gradation value; A display device in which an R display element, a G display element, and a B display element in a dot are adjacent to a sixth image in a display state corresponding to a gradation value for realizing a luminance of 1/4 of the maximum luminance. And whether or not a boundary is visually recognized between the fifth image and the sixth image is visually determined.
When the boundary is visually recognized between the fourth image and the fifth image, a method of changing the setting of the driving device of the display device so that the boundary is not visually recognized may be used.

  An inspection image including the adjacent first image and the second image and the adjacent fifth image and the sixth image may be displayed on the display device.

  According to the present invention, even when the R display element, the G display element, and the B display element exhibit colors, it is possible to prevent fine stripes from being visually recognized. As a result, there is no difference in the appearance of the two images when determining whether or not a boundary is visually recognized between the two images, and a comparison of the luminance values of the two regions is performed for each of R, G, and B. You don't have to do this for each color.

  Further, it is not necessary to prepare a measuring device or a place for measuring the luminance, the inspection can be performed in a short time, and a simple γ characteristic inspection can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a case where the number of gradations of luminance of each display element of the display device to be subjected to the γ characteristic inspection is 256 will be described as an example. That is, the case where each display element is in a display state corresponding to each gradation from gradation value 0 to gradation value 255 will be described as an example.

  First, an example of a display device to which the γ characteristic inspection method of the present invention is applied will be described. Here, a case where the display device is a liquid crystal display device (liquid crystal display module) including a TFT (Thin Film Transistor) liquid crystal display panel will be described as an example. FIG. 1 is an explanatory diagram illustrating a configuration example of a display element provided in a display panel of a liquid crystal display device. Each display element is provided with a TFT 1 and a display electrode 2. In FIG. 1, only one TFT 1 and display electrode 2 are shown, and illustration of other TFTs and display electrodes is omitted. The liquid crystal display panel is provided with a common electrode 3 facing each display electrode. In this example, a case where there is one common electrode provided in the liquid crystal display panel will be described as an example. A liquid crystal layer (not shown) is sandwiched between the common electrode 3 and each display electrode 2.

  Each display element is arranged in a matrix, and R, G, and B color filters are provided in a predetermined order in each row so as to overlap individual display elements in each row. For example, in each row, color filters are provided in the order of R, G, B, R, G, B,. The display element provided with the R color filter is an R display element. Similarly, a display element provided with the G color filter is a G display element, and a display element provided with the B color filter is a B display element. Then, as shown in FIG. 15, a combination of the R display element 52, the G display element 53, and the B display element 54 arranged in order becomes one dot 51. As a result, each dot is also arranged in a matrix.

The display electrode 2 is connected to the drain 1b of the TFT1. Further, the source 1 c of the TFT 1 is connected to the source wiring 4, and the gate 1 a of the TFT 1 is connected to the gate wiring 5. When the potential of the gate 1a is set to a predetermined on-potential via the gate wiring 5, the source 1c and the drain 1b are brought into conduction, and the display electrode 2 is set to the same potential as the source wiring 4. When the potential of the gate 1a is set to a predetermined off potential, the source 1c and the drain 1b are brought into a non-conductive state, and the source line 4 and the display electrode 2 are also switched to a non-conductive state. The predetermined on-potential is a predetermined potential of the gate 1a for bringing the source 1c and the drain 1b into a conductive state. The predetermined off potential is a predetermined potential of the gate 1a for bringing the source 1c and the drain 1b into a non-conductive state. Hereinafter, the predetermined on potential is represented as V _gH and the predetermined off potential is represented as V _gL .

  FIG. 2 is an explanatory diagram schematically illustrating an example of a driving device provided in the liquid crystal display device. The driving device 5 that drives the liquid crystal display panel 1 is realized by an IC, for example. Hereinafter, the driving device is referred to as a driving IC. The drive IC 5 includes a source driver 7, a gate driver 8, and a control unit 6 that controls the source driver 7 and the gate driver 8.

  Each gate wiring 5 (see FIG. 1) is connected to the gate 1a of each TFT 1 in one row for each row. Each gate line 5 is connected to a gate driver 8 (see FIG. 2). Each source wiring 4 (see FIG. 1) is connected to the source 1c of each TFT 1 in one column. Each source line 4 is connected to a source driver 7 (see FIG. 2).

The gate driver 8 scans while sequentially selecting the gate wiring, sets the potential of the selected gate wiring to V _gH, and sets the potential of the unselected gate wiring to V _gL . During the selection period of the row selected by the gate driver 8, the source driver 7 sets the potential of each source wiring according to the image data for one row corresponding to the selected gate wiring. As a result, a voltage corresponding to the image data is applied to the liquid crystal between each display electrode 2 and the common electrode 3 (see FIG. 1) for one row corresponding to the selected gate wiring. In addition, electric charges are accumulated in the display elements for one row. Thereafter, by sequentially selecting the gate wiring in the same manner, an image for one screen is displayed on the liquid crystal display panel 1.

  The control unit 6 outputs a control signal instructing switching of the selected row to the source driver 7 and the gate driver 8. In addition, the control unit 6 outputs image data input from the outside to the source driver 7. When a control signal instructing switching of the selected row is input, the gate driver 8 switches the gate wiring to be selected. Further, when a control signal instructing switching of the selected row is input, the source driver 7 sets the potential of each source wiring based on the image data of the selected row.

  The source driver 7 sets the potential of the source line 4 to a potential corresponding to the gradation value indicated by the image data. For example, if the image data indicates that the luminance of each display element of R, G, B at one dot in the selected row is the maximum gradation, each display of R, G, B included in that dot The potential of the source wiring connected to the element is set to a potential corresponding to the gradation value 255 (in this case, the dot is displayed in white). The same applies when other gradation values are specified in the image data. The driving IC 5 includes a register (not shown). The register stores data for specifying the relationship between the gradation value indicated in the image data and the potential to be set for the source wiring in accordance with the gradation value. The control unit 6 controls the source driver 7 so as to set a potential corresponding to the gradation value indicated in the image data to the source wiring in accordance with the data stored in the register. Even if the gradation value indicated in the image data does not change, if the data stored in the register is changed, the potential set in the source wiring also changes.

  Next, the gamma characteristic inspection method of the present invention will be described. In the present invention, the minimum brightness (brightness during black display) when performing grayscale display is set to 0, and the maximum brightness (brightness during white display) is set to 1. Then, the setting of the display element for setting the minimum luminance to 0 and the setting of the display element for setting the maximum luminance to 1 are used as references. Then, an image (first image) having a relative luminance of 0.5 is displayed by combining the reference settings, and an image is displayed adjacent to the image with a gradation value at which the relative luminance should be 0.5. (Second image) is displayed. If the brightness of the two images is equal and a boundary is not visually recognized between the two images, it is determined that the relative brightness of 0.5 can be realized with a gradation value at which the relative brightness should be 0.5. By this determination, the setting of the display element for setting the relative luminance to 0.5 can also be added to the reference setting.

  Further, by combining the setting of the display element for setting the relative brightness to 0.5 and the setting of the display element for setting the maximum brightness to 1, an image (third image) having a relative brightness of 0.75 is obtained. In addition to displaying, an image (fourth image) is displayed adjacent to the image with a gradation value at which the relative luminance should be 0.75. If the luminances of the two images are equal and no boundary is visually recognized between the two images, it is determined that the relative luminance of 0.75 can be realized with the gradation value that should be 0.75.

  Similarly, an image in which the relative luminance is 0.25 by combining the setting of the display element for setting the relative luminance to 0.5 and the setting of the display element for setting the minimum luminance to 0 (fifth image). And an image (sixth image) is displayed adjacent to the image with a gradation value at which the relative luminance should be 0.25. If the luminances of the two images are equal and no boundary is visually recognized between the two images, it is determined that the relative luminance of 0.25 can be realized with the gradation value that the relative luminance should be 0.25.

  The same determination may be repeated further.

  FIG. 3 is an explanatory diagram showing an example of an image (hereinafter referred to as an inspection image) displayed on the display panel 1 of the liquid crystal display device to be inspected in the γ characteristic inspection method of the present invention. The inspection image illustrated in FIG. 3 includes a first image 11, a second image 12, a third image 13, a fourth image 14, a fifth image 15, and a sixth image 16. Is included. Then, the image data of the inspection image including these six types of images 11 to 16 is input to the control unit 6. The control unit 6 controls the source driver 7 and the gate driver 8 to display an inspection image, and the inspector visually observes the displayed inspection image and performs a γ characteristic inspection. Hereinafter, each image from the first image 11 to the sixth image 16 will be described.

  In the inspection image, the first image 11 and the second image 12 are arranged so that the ends are adjacent to each other. Similarly, the 3rd image 13 and the 4th image 14 are arrange | positioned so that edge parts may contact and adjoin. Similarly, the 5th image 15 and the 6th image 16 are arrange | positioned so that edge parts may contact and adjoin.

  FIG. 4 shows an example of a first image displayed by each dot including an R display element, a G display element, and a B display element. Each screen from FIG. 4 to FIG. 10 shown below shows an image of an area corresponding to 4 dots. In each screen from FIG. 4 to FIG. 10, the value shown in the display element represents the gradation value of the display element. In the present embodiment, the case where the maximum gradation value is 255 and the minimum gradation value is 0 is illustrated.

  The first image 11 is an image in which two types of displays are arranged in a checkered pattern. One of the two types of display is set so that only one display element among the R display element 52, the G display element 53, and the B display element 54 is in a display state corresponding to the maximum gradation value 255 within one dot. The other two display elements are displayed in a display state corresponding to the minimum gradation value 0. The dots 112 and 113 shown in FIG. 4 are in this display state. In the example shown in FIG. 4, in the dots 112 and 113, only the G display element 53 among the R display element 52, the G display element 53, and the B display element 54 is in a display state corresponding to the maximum gradation value 255. The other two display elements (R display element 52 and B display element 54) are in a display state corresponding to the minimum gradation value 0.

  The other of the two types of displays in the first image 11 is such that two display elements of the R display element 52, the G display element 53, and the B display element 54 are set to the maximum gradation value 255 within one dot. As the corresponding display state, the remaining one display element is displayed in a display state corresponding to the minimum gradation value 0. The dots 111 and 114 shown in FIG. 4 are in this display state. In the example shown in FIG. 4, in the dots 111 and 114, the R display element 52 and the B display element 54 among the R display element 52, the G display element 53, and the B display element 54 are displayed according to the maximum gradation value 255. It is said. The remaining G display elements 53 are in a display state corresponding to the minimum gradation value 0.

  In the example shown in FIG. 4, since the dots 111 and 114 are pink and the dots 112 and 113 are green, the checkered pattern is pink and green.

  Further, in each dot displaying the first image 11, two display elements are set to the same display state, and the display states of the remaining display elements are made different from the display states of the two display elements. A combination of two display elements having the same display state is common to each dot displaying the first image 11. Two display elements having the same display state within the dot are preferably display elements at both ends of the dot. In the example shown in FIG. 4, since the display elements at both ends of each dot are the R display element 52 and the B display element 54, the display states of the R display element 52 and the B display element 54 are the same in each dot.

  FIG. 5 shows a checkered pattern image in which white and black are displayed by each dot. In a white and black checkered pattern image, white display dots and black display dots are adjacent to each other. The R display element 52, the G display element 53, and the B display element 54 in the dots 112 and 113 shown in FIG. 5 are all in a display state corresponding to the maximum gradation value 255, and the brightness of the dots 112 and 113 is gray. The maximum brightness of the scale. That is, the dots 112 and 113 are displayed in white. Further, the R display element 52, the G display element 53, and the B display element 54 in the dots 111 and 114 shown in FIG. 5 are all in a display state corresponding to the minimum gradation value 0, and the brightness of the dots 111 and 114 is set. Is the minimum luminance of gray scale. That is, the dots 111 and 114 are displayed in black. In the example shown in FIG. 5, a checkered pattern image is displayed with dots having the minimum luminance of gray scale and dots having the maximum luminance, so the relative luminance of the entire image (relative luminance with respect to the maximum luminance of gray scale) is 0.5. In addition, when all the display elements in the dot are set in a display state corresponding to the minimum gradation value, the minimum luminance is always obtained, and in a case where all the display elements in the dot are set in a display state according to the maximum gradation value. Always has the highest luminance, so the relative luminance of the image shown in FIG. 5 is always 0.5 regardless of the γ characteristic of the liquid crystal display device.

  Here, when comparing the first image 11 and the image shown in FIG. 5, an R display element, a G display element corresponding to the gradation value 255 in the four dots 111 to 114 arranged in 2 rows and 2 columns, The number of B display elements is equal. Similarly, the numbers of R display elements, G display elements, and B display elements corresponding to the gradation value 0 are also equal. Therefore, like the image shown in FIG. 5, the first image 11 is a grayscale image having a relative luminance of 0.5 regardless of the γ characteristic of the liquid crystal display device.

  FIG. 6 shows an example of a second image displayed by each dot including an R display element, a G display element, and a B display element. The second image 12 displays the R display element 52, the G display element 53, and the B display element 54 in each dot in a display state corresponding to a gradation value for realizing a luminance that is ½ of the maximum luminance. It is an image. When the number of gradations is 256, the gradation value for realizing a luminance of ½ of the maximum luminance is 186. In the example illustrated in FIG. 6, in any of the dots 121 to 124, the R display element 52, the G display element 53, and the B display element 54 are all in a display state according to the gradation value 186. However, even if each display element of each pixel is in a display state corresponding to the gradation value 186 by the driving IC 5 (see FIG. 2), there is a correspondence relationship between the gradation value and the potential to be set for the source wiring. If it is not appropriate and the γ characteristic is not appropriate, the relative luminance of the second image 12 is not necessarily 0.5.

  FIG. 7 shows an example of a third image displayed by each dot including the R display element, the G display element, and the B display element. The third image 13 is an image in which two types of displays are arranged in a checkered pattern. One of the two types of display in the third image is within one dot, and only one of the R display element 52, the G display element 53, and the B display element 54 is set according to the maximum gradation value 255. As the display state, the other two display elements are displayed in a display state corresponding to a gradation value (186 in this example) for realizing a luminance of ½ of the maximum luminance. The dots 132 and 133 shown in FIG. 7 are in this display state. In the example illustrated in FIG. 7, in the dots 132 and 133, only the G display element 53 among the R display element 52, the G display element 53, and the B display element 54 is in a display state corresponding to the maximum gradation value 255. The other two display elements (the R display element 52 and the B display element 54) are in a display state corresponding to the gradation value 186.

  The other of the two types of displays in the third image 13 is such that two display elements of the R display element 52, the G display element 53, and the B display element 54 are set to the maximum gradation value 255 within one dot. As the corresponding display state, the remaining one display element is a display state corresponding to a gradation value (186 in this example) for realizing a luminance of ½ of the maximum luminance. The dots 131 and 134 shown in FIG. 7 are in this display state. In the example shown in FIG. 7, in the dots 131 and 134, the R display element 52 and the B display element 54 among the R display element 52, the G display element 53, and the B display element 54 are displayed according to the maximum gradation value 255. It is said. The remaining G display elements 53 are in a display state corresponding to the gradation value 186.

  In each dot displaying the third image 13, two display elements are set to the same display state, and the display states of the remaining display elements are made different from the display states of the two display elements. A combination of two display elements having the same display state is common to each dot displaying the third image 13. Two display elements having the same display state within the dot are preferably display elements at both ends of the dot. This is the same as in the case of the first image 11.

  If it is guaranteed that the relative luminance of the second image 12 is 0.5, the relative luminance of the third image 13 is 0.75. That is, if it is guaranteed that a relative luminance of 0.5 can be realized when all the display elements 52 to 54 of each dot are in a display state corresponding to the gradation value 186, the relative luminance of the third image 13 is 0.75.

  FIG. 8 shows an example of a fourth image displayed by each dot including the R display element, the G display element, and the B display element. The fourth image 14 displays the R display element 52, the G display element 53, and the B display element 54 in each dot in a display state corresponding to a gradation value for realizing a luminance of 3/4 of the maximum luminance. It is an image. When the number of gradations is 256, the gradation value for realizing 3/4 of the maximum luminance is 224. In the example shown in FIG. 8, the R display element 52, the G display element 53, and the B display element 54 are all in a display state corresponding to the gradation value 224 in any of the dots 141 to 144. However, as in the case of the second image 12, the γ characteristic is appropriate even when the display elements of the pixels are all in the display state corresponding to the gradation value 224 by the driving IC 5 (see FIG. 2). Otherwise, the relative brightness of the fourth image 14 is not always 0.75.

  FIG. 9 shows an example of a fifth image displayed by each dot including the R display element, the G display element, and the B display element. The fifth image 15 is an image in which two types of displays are arranged in a checkered pattern. One of the two types of display in the fifth image is within one dot, and only one display element among the R display element 52, the G display element 53, and the B display element 54 is ½ of the maximum luminance. In the display state corresponding to the gradation value for realizing the luminance (186 in this example), the other two display elements are displayed in a display state corresponding to the minimum gradation value 0. The dots 152 and 153 shown in FIG. 9 are in this display state. In the example shown in FIG. 9, among the R display element 52, the G display element 53, and the B display element 54, only the G display element 53 is in a display state corresponding to the gradation value 186 in the dots 152 and 153. The other two display elements (R display element 52 and B display element 54) are in a display state corresponding to the minimum gradation value 0.

  The other of the two types of display in the fifth image 15 is one dot, and the two display elements of the R display element 52, the G display element 53, and the B display element 54 are ½ of the maximum luminance. As a display state corresponding to the gradation value for realizing the luminance of 186 (in this example, 186), the remaining one display element is displayed in a display state corresponding to the minimum gradation value 0. The dots 151 and 154 shown in FIG. 9 are in this display state. In the example shown in FIG. 9, the R display element 52 and the B display element 54 among the R display element 52, the G display element 53, and the B display element 54 are displayed in the dots 151 and 154 according to the gradation value 186. Yes. The remaining G display elements 53 are in a display state corresponding to the minimum gradation value 0.

  Further, in each dot displaying the fifth image 15, two display elements are set in the same display state, and the display states of the remaining display elements are made different from the display states of the two display elements. A combination of two display elements having the same display state is common to each dot displaying the fifth image 15. Two display elements having the same display state within the dot are preferably display elements at both ends of the dot. This is the same as in the case of the first image 11.

  If it is guaranteed that the relative luminance of the second image 12 is 0.5, the relative luminance of the fifth image 15 is 0.25. That is, if it is guaranteed that a relative luminance of 0.5 can be realized when all the display elements 52 to 54 of each dot are in a display state corresponding to the gradation value 186, the relative luminance of the fifth screen 15 is 0.25.

  FIG. 10 shows an example of a sixth image displayed by each dot including the R display element, the G display element, and the B display element. The sixth image 16 displays the R display element 52, the G display element 53, and the B display element 54 in each dot in a display state corresponding to a gradation value for realizing a luminance of 1/4 of the maximum luminance. It is an image. When the number of gradations is 256, the gradation value for realizing a luminance of 1/4 of the maximum luminance is 136. In the example shown in FIG. 10, the R display element 52, the G display element 53, and the B display element 54 are all in a display state corresponding to the gradation value 136 in any of the dots 161 to 164. However, as in the case of the second image 12, the γ characteristic is appropriate even if each display element of each pixel is in a display state corresponding to the gradation value 136 by the driving IC 5 (see FIG. 2). Otherwise, the relative luminance of the sixth image 16 is not necessarily 0.25.

  FIG. 11 is a flowchart showing the procedure of the gamma characteristic inspection method of the present invention. First, an operator who performs inspection inputs image data of an inspection image to the driving IC 5 (see FIG. 2), and causes the driving IC 5 to display the inspection image on the display panel 1 of the liquid crystal display device to be inspected (step S1). ).

  Subsequently, the operator looks at the inspection image, and whether or not a boundary is visually recognized between the first image 11 and the second image 12 that are arranged so that the end portions are in contact with each other. Is determined (step S2). If no boundary is visually recognized in step S2, the process proceeds to step S3. If the boundary is visually recognized in step S2, it is determined that the γ characteristic of the liquid crystal display device to be inspected is inappropriate.

  Here, it will be described that the γ characteristic can be determined to be inappropriate when the boundary is visually recognized. FIG. 12 is an explanatory diagram illustrating an example of the γ characteristic. The curve shown in FIG. 12A represents an appropriate (preferred) γ characteristic having a γ value of 2.2. The straight line shown in FIG. 12A represents an inappropriate γ characteristic having a γ value of 1. In addition, the quadrangular, triangular, and round plots shown in FIG. 12A indicate that the relative luminance is 0.25, 0.5, and 0.75, respectively. FIG. 12B shows relative luminance values for the gradation values 0, 136, 186, 224, and 255 in each γ characteristic where γ = 1 and γ = 2.2.

  As already described, the first image 11 is a grayscale image having a relative luminance of 0.5 regardless of the γ characteristic of the liquid crystal display device. Further, the relative luminance of the second image 12 is not necessarily 0.5 when the γ characteristic is not appropriate. For example, in the inappropriate γ characteristic illustrated in FIG. 12, the relative luminance is 0.73 even when all the display elements of the dots are in the display state corresponding to the gradation value 186.

  The first image 11 is a criterion for determining whether or not the relative brightness of the adjacent second image 12 is 0.5. If the luminance in the first image 11 and the luminance in the second image 12 are equal, the boundary between the first image 11 and the second image 12 is not visually recognized in the inspection image (see FIG. 3). In this case, since the relative luminance in the first image 11 is 0.5, the relative luminance in the second image 12 is also 0.5. That is, in the liquid crystal display device to be inspected, it can be determined that the display state corresponding to at least the gradation value 186 is the display state corresponding to the gradation value 186 in the preferable γ characteristic. In this case, the process proceeds to step S3.

  Further, if the luminance in the first image 11 and the luminance in the second image 12 are different, the boundary between the first image 11 and the second image 12 is caused by the luminance difference in the inspection image (see FIG. 3). Visible. In this case, the relative luminance in the second image 12 is not 0.5, and it can be determined that the display state corresponding to the gradation value 186 is not a display state corresponding to the gradation value 186 in the preferable γ characteristic. That is, it can be determined that the γ characteristic of the liquid crystal display device is not an appropriate γ characteristic.

  FIG. 13 shows the luminance and boundary visibility of the first image and the second image in the case of appropriate γ characteristics and inappropriate γ characteristics, respectively. FIG. 13 illustrates the case where γ = 1 as an inappropriate γ characteristic.

  If it is determined in step S2 that the boundary is not visually recognized, the display state corresponding to at least the gradation value 186 in the liquid crystal display device to be inspected is the display state corresponding to the gradation value 186 in the preferable γ characteristic. Can be determined. However, this determination alone cannot determine that the γ characteristic of the liquid crystal display device to be inspected is a preferable γ characteristic. For example, the γ characteristic indicated by the broken line or the alternate long and short dash line in FIG. 14 is an inappropriate γ characteristic. When the γ characteristic to be inspected is the γ characteristic exemplified by the alternate long and short dash line in FIG. 14, the boundary is visually recognized in the determination in step S <b> 2, so it can be determined that the γ characteristic is inappropriate. However, when the γ characteristic to be inspected is the γ characteristic illustrated by the broken line in FIG. 14, the display state corresponding to the gradation value 186 is the display state corresponding to the gradation value 186 in the preferable γ characteristic. The boundary is not visually recognized. Therefore, even if the boundary is not visually recognized in step S2, the determination after step S3 shown below is also performed.

  When the boundary is not visually recognized in step S <b> 2, the operator visually checks the inspection image, and there is a boundary between the third image 13 and the fourth image 14 that are arranged so that the ends are in contact with each other. It is determined whether it is visually recognized (step S3). If the boundary is not visually recognized in step S3, the process proceeds to step S4. If the boundary is visually recognized in step S3, it is determined that the γ characteristic of the liquid crystal display device to be inspected is inappropriate.

  Since the boundary is not visually recognized in step S2, it is guaranteed that the relative luminance of the second image 12 is 0.5. As a result, the relative luminance of the third image 13 is 0.75 even in the case of an inappropriate γ characteristic illustrated by a broken line in FIG. In step S3, it is determined whether or not the relative luminance of the fourth image 14 is 0.75 with reference to the third image 13 having a relative luminance of 0.75. That is, if the boundary between the third image 13 and the fourth image 14 is not visually recognized, the luminances of the two images are equal, and the relative luminance of the fourth image 14 is 0.75. If the relative luminance of the fourth image 14 is 0.75, the display state corresponding to the gradation value 224 in the liquid crystal display device to be inspected corresponds to the gradation value 224 in the preferable γ characteristic. Displayed. Further, if the boundary between the third image 13 and the fourth image 14 is visually recognized, it can be understood that the brightness of the two images is different. In this case, since the display state corresponding to the gradation value 224 is not the display state corresponding to the gradation value 224 in the preferable γ characteristic, it can be determined that the γ characteristic of the liquid crystal display device is not an appropriate γ characteristic.

  When the boundary is not visually recognized in step S <b> 3, the worker visually checks the inspection image, and there is a boundary between the fifth image 15 and the sixth image 16 that are arranged so that the end portions are in contact with each other. It is determined whether it is visually recognized (step S4). If the boundary is not visually recognized in step S4, the γ characteristic to be inspected may be regarded as a preferable γ characteristic and the γ characteristic inspection may be terminated. If the boundary is visually recognized in step S4, it is determined that the γ characteristic of the liquid crystal display device to be inspected is inappropriate.

  Since the boundary is not visually recognized in step S2, it is guaranteed that the relative luminance of the second image 12 is 0.5. As a result, the relative luminance of the fifth image 15 is 0.25 even in the case of an inappropriate γ characteristic illustrated by a broken line in FIG. In step S4, it is determined whether the relative brightness of the sixth image 16 is 0.25 with reference to the fifth image 15 having a relative brightness of 0.25. That is, if the boundary between the fifth image 15 and the sixth image 16 is not visually recognized, it can be determined that the luminances of the two images are equal and the relative luminance of the sixth image 16 is 0.25. If the relative luminance of the sixth image 16 is 0.25, the display state corresponding to the gradation value 136 in the liquid crystal display device to be inspected corresponds to the gradation value 136 in the preferable γ characteristic. It can be determined that the display state is set. Further, if the boundary between the fifth image 15 and the sixth image 16 is visually recognized, it can be understood that the luminances of the two images are different. In this case, since the display state corresponding to the gradation value 136 is not the display state corresponding to the gradation value 136 in the preferable γ characteristic, it can be determined that the γ characteristic of the liquid crystal display device is not an appropriate γ characteristic.

  If the process proceeds in the order of steps S2, S3, and S4 and the boundary is not visually recognized in step S4, the display states corresponding to the gradation values 186, 224, and 136 in the inspection target are all the display states in the preferable γ characteristics. Will match. In this case, it can be considered that the γ characteristic of the liquid crystal display device to be inspected is a preferable γ characteristic, and it may be determined that the γ characteristic of the inspection target is appropriate.

  In addition, it is preferable to perform determination of step S2, S3, S4 by visually inspecting an inspection image from the front. This is because the boundary may be visually recognized when the inspection image is viewed from an oblique direction.

  Further, after step S4, the γ characteristic inspection may be further continued. Since the relative brightness of the second image 12, the fourth image 14, and the sixth image 16 is guaranteed to be 0.5, 0.75, and 0.25, respectively, the first, third, and In addition to the fifth image, it is possible to display a larger number of images serving as luminance standards. Based on these images, it is determined in the same manner as steps S2, S3, and S4 whether or not the display state corresponding to the gradation values other than the gradation values 186, 224, and 136 is the display state in the appropriate γ characteristics. May be.

  In the present invention, it is determined whether or not the luminance of one image is equal to the luminance of the reference image depending on whether or not a boundary between adjacent images is visually recognized, and an inspection is performed based on the determination result. It is determined whether or not the γ characteristic of the target liquid crystal display device is appropriate. Therefore, the γ characteristic inspection can be easily performed without a measuring device or a place for measuring the luminance. In addition, the γ characteristic inspection can be performed in a short time. Therefore, many liquid crystal display devices can be inspected, and the number of sampling in the sampling inspection can be increased, or a total inspection can be performed. In particular, since an inexpensive display device has a large individual difference, it is necessary to perform a γ characteristic test on a large number of display devices. However, according to the present invention, a γ characteristic test can be easily performed on a large number of display devices. it can.

  Further, when the first image 11, the third image 13, and the fifth image 15 are displayed, the display states of the display elements adjacent to each other are made different. Therefore, even if each of the R, G, and B display elements exhibits a color, fine stripes are not visually recognized. Therefore, for example, when it is determined whether or not the boundary between the first image 11 and the second image 12 is visually recognized, the fineness of the two images can be obtained by visually recognizing fine stripes in the first image 11. Can be prevented from being different. Then, it is possible to prevent the boundary from being visually recognized due to the presence or absence of fine stripes rather than luminance. Similarly, it is determined whether the boundary between the third image 13 and the fourth image 14 is visually recognized (step S3), and whether the boundary between the fifth image 15 and the sixth image 16 is visually recognized. Even in the determination (step S4), it is possible to prevent the boundary from being visually recognized due to the presence or absence of stripes rather than luminance. Therefore, it is possible to accurately determine whether or not a boundary between two images due to a luminance difference is visually recognized.

  Note that both the first image shown in FIG. 4 and the image shown in FIG. 5 can be used as images serving as a reference for the brightness of 0.5 in step S2. However, in the image shown in FIG. 5, the display state of the display element is the same within each dot. That is, the display states of the three display elements arranged side by side within each dot are the same. Therefore, compared to the first image shown in FIG. 4, the checkerboard pattern is easily recognized by the operator. Then, the boundary between the two images may be visually recognized based on whether the checkerboard pattern is recognized instead of the luminance. Therefore, it is preferable to use the first image (see FIG. 4) described above as a reference screen with a luminance of 0.5 instead of the image shown in FIG.

  Further, instead of the third image (see FIG. 7), the display state of the display elements in a certain dot is set to the display state corresponding to the maximum gradation value 255, and the display elements in the dots adjacent to the dot are displayed. It is possible to use a checkered pattern image in which the display states are all in accordance with the gradation value 186. However, in that case, the checkerboard pattern is easily recognized as in the image shown in FIG. 5, and therefore it is preferable to use the third image illustrated in FIG. 7.

  Further, instead of the fifth image (see FIG. 9), the display state of the display elements in a certain dot is set to the display state corresponding to the minimum gradation value 0, and the display elements in the dots adjacent to the dot are displayed. It is possible to use a checkered pattern image in which the display states are all in accordance with the gradation value 186. However, in this case as well, it is easy to recognize a checkered pattern as in the image shown in FIG.

  Moreover, in said embodiment, although determination of step S2, S3, S4 is performed, determination of step S3 is performed after step S2, and if a boundary is not visually recognized by step S3, (gamma) characteristic of test object will be The γ characteristic inspection may be terminated assuming that the γ characteristic is preferable. If the display states corresponding to the gradation values 186 and 224 all match the display state in the preferable γ characteristic, the γ characteristic to be inspected generally matches the preferable γ characteristic, so the γ characteristic inspection is terminated in step S3. Can do. However, it is preferable to perform both the determinations in steps S3 and S4 from the viewpoint of more accurate inspection. When the determination in step S4 is not performed, the inspection image including the first image 11 and the second image 12 that are adjacent to each other and the third image 13 and the fourth image 14 that are adjacent to each other is liquid crystal. What is necessary is just to display on a display apparatus.

  Also, after step S2, the determination in step S4 is performed without performing the determination in step S3. If the boundary is not visually recognized in step S4, the γ characteristic to be inspected is regarded as a preferable γ characteristic and the γ characteristic inspection is terminated. May be. If the display state corresponding to the gradation values 186 and 136 matches the display state in the preferable γ characteristic, the γ characteristic to be inspected generally matches the preferable γ characteristic. Therefore, even if the determination in step S3 is omitted. Good. However, as already described, it is preferable to perform both determinations in steps S3 and S4. When the determination in step S3 is not performed, the inspection image including the first image 11 and the second image 12 adjacent to each other, and the fifth image 15 and the sixth image 16 adjacent to each other is liquid crystal. What is necessary is just to display on a display apparatus.

  In addition, an inspection image including the adjacent first image 11 and the second image 12, an inspection image including the adjacent third image 13 and the fourth image 14, and the adjacent fifth image 15 and the sixth image. The inspection image including the image 16 may be displayed separately on the liquid crystal display device. However, the test images including the first image 11 to the sixth image 16 as shown in FIG. 3 are displayed on the display device, so that the determination in steps S2 to S4 is performed without switching the test images. be able to. Therefore, it is preferable to display the inspection image illustrated in FIG. 3 from the viewpoint of inspection efficiency.

  In the above description, the method for inspecting whether or not the γ characteristic of the inspection target is an appropriate γ characteristic has been described. However, the γ characteristic of the inspection target may be adjusted. Specifically, for example, when the liquid crystal display device performs positive display, if the boundary between the first image 11 and the second image 12 is visually recognized in step S2, the inspection target is set so that the boundary is not visually recognized. You may adjust the (gamma) characteristic of a liquid crystal display device. At this time, if the second image 12 is viewed brighter than the first image 11, it means that the voltage applied to the liquid crystal is insufficient. In that case, the set potential of the source wiring corresponding to the gradation value may be changed so that the voltage between the common electrode 3 and the display electrode 2 becomes high. Further, if the second image 12 is viewed darker than the first image 11, it means that the voltage applied to the liquid crystal is excessive. In that case, the set potential of the source wiring corresponding to the gradation value may be changed so that the voltage between the common electrode 3 and the display electrode 2 becomes low. If the boundary between the first image 11 and the second image 12 is no longer visually recognized by changing the set potential of the source wiring corresponding to the gradation value, the process proceeds to step S3.

  If the boundary between the third image 13 and the fourth image 14 is visually recognized in step S3, the γ characteristic of the liquid crystal display device to be inspected may be adjusted so that the boundary is not visually recognized. At this time, similarly to the adjustment after step S2, if the fourth image 14 is viewed brighter than the third image 13, the voltage between the common electrode 3 and the display electrode 2 is increased. In addition, the set potential of the source wiring corresponding to the gradation value may be changed. Further, if the fourth image 14 is viewed darker than the third image 13, the source wiring corresponding to the gradation value is set so that the voltage between the common electrode 3 and the display electrode 2 is lowered. The set potential may be changed. If the boundary between the third image 13 and the fourth image 14 becomes invisible by changing the set potential of the source wiring corresponding to the gradation value, the process proceeds to step 4.

  Similarly, if the boundary between the fifth image 15 and the sixth image 16 is visually recognized in step S4, the γ characteristic of the liquid crystal display device to be inspected may be adjusted so that the boundary is not visually recognized. . At this time, similarly to the adjustment after step S2, if the sixth image 16 is viewed brighter than the fifth image 15, the voltage between the common electrode 3 and the display electrode 2 is increased. In addition, the set potential of the source wiring corresponding to the gradation value may be changed. Further, if the sixth image 16 is viewed darker than the fifth image 15, the source wiring corresponding to the gradation value is set so that the voltage between the common electrode 3 and the display electrode 2 is lowered. The set potential may be changed.

  In the adjustment of the γ characteristic after steps S2, S3, and S4, not only the set potential to the source wiring corresponding to a specific gradation value is changed, but the source wiring corresponding to the gradation value is changed over each gradation. Change the set potential. In order to change the correspondence between the gradation value and the potential to be set to the source wiring in accordance with the gradation value, data stored in a register (not shown) included in the drive IC 5 is changed. Good.

  After step S4, when the gamma characteristic inspection is continued using a reference image other than the first, third, and fifth images, the gamma characteristic is adjusted in the same manner as described above when the boundary is visually recognized. May be.

  In addition, at the end of the adjustment of the γ characteristics, a plurality of dots arranged in succession are displayed on the liquid crystal display device with a gradation bar that displays a state corresponding to each gradation value from the minimum gradation value to the maximum gradation value, Confirm that there is no gradation jump (that is, the luminance changes smoothly in the gradation bar).

  If the γ characteristic is adjusted as described above, γ adjustment can be performed without measuring the luminance, so that it is not necessary to prepare an apparatus or a place for measuring the luminance.

  Although the case where the number of gradations of the display device is 256 has been described as an example in the above description, the number of gradations of the display device to be inspected is not limited to 256.

  The combination of the adjacent first image and second image can be used in addition to the γ characteristic inspection. When the first image and the second image are displayed adjacent to each other on the liquid crystal display device in which the γ characteristics are preferably adjusted, the boundary is not visually recognized because the luminance is equal. However, even in that case, the boundary may be visually recognized when viewed from an oblique direction. By utilizing this, for example, it is possible to display an image in which a figure is visually recognized only when viewed from an oblique direction.

  The present invention is suitably applied to γ characteristic inspection and γ characteristic adjustment of a display device.

Explanatory drawing which shows the structural example of the display element provided in the display panel of a liquid crystal display device. Explanatory drawing which shows typically the example of the drive device with which a liquid crystal display device is provided. Explanatory drawing which shows the example of a test | inspection image. Explanatory drawing which shows the example of a 1st image. Explanatory drawing which shows the checkered pattern-like image by which white and black are displayed by each dot. Explanatory drawing which shows the example of a 2nd image. Explanatory drawing which shows the example of a 3rd image. Explanatory drawing which shows the example of a 4th image. Explanatory drawing which shows the example of a 5th image. Explanatory drawing which shows the example of a 6th image. The flowchart which shows the procedure of the gamma characteristic inspection method of this invention. Explanatory drawing which shows the example of (gamma) characteristic. Explanatory drawing which shows the comparison with an appropriate gamma characteristic and an improper gamma characteristic. Explanatory drawing which shows an appropriate (gamma) characteristic and an improper (gamma) characteristic. Explanatory drawing which shows one dot. Explanatory drawing which shows the relationship between the relative luminance y and the gradation value n. Explanatory drawing which shows the state which made the certain row | line | column the maximum brightness | luminance of a gray scale, and made the other adjacent row | line | column the minimum brightness | luminance of a gray scale in the area | region where two figures with different brightness | luminances are arrange | positioned at the vertical stripe form. Explanatory drawing which shows the state which made a certain line the maximum brightness | luminance of a gray scale, and made the other adjacent line the minimum brightness | luminance of a gray scale in the area | region where two figures with different brightness | luminance were arrange | positioned at horizontal stripe form.

Explanation of symbols

11 1st image 12 2nd image 13 3rd image 14 4th image 15 5th image 16 6th image 52 R display element 53 G display element 54 B display element

Claims (6)

Display in which dots in which R display elements that are display elements for displaying red, G display elements that are display elements for displaying green, and B display elements that are display elements for displaying blue are combined are arranged in a matrix A gamma characteristic inspection method for an apparatus,
Within one dot, only one of the R, G, and B display elements is displayed according to the maximum gradation value, and the other two display elements are displayed according to the minimum gradation value. And the two display elements among the R display element, the G display element, and the B display element within one dot are set in a display state corresponding to the maximum gradation value, and the remaining one display element is set to the minimum gradation value. The first image in which the display state corresponding to the first display is arranged in a checkered pattern, and the R display element, the G display element, and the B display element in each dot have a luminance that is ½ of the maximum luminance. A second image having a display state corresponding to the gradation value for display is displayed adjacent to the display device, and whether or not a boundary is visually recognized between the first image and the second image is visually checked. Judge with
After determining that no boundary is visible between the first image and the second image,
Within one dot, only one of the R display element, G display element, and B display element is set in a display state corresponding to the maximum gradation value, and the other two display elements are set to have a luminance of ½ of the maximum luminance. Display in a display state corresponding to the gradation value for realizing, and a display state in which the two display elements among the R display element, the G display element, and the B display element are in one dot according to the maximum gradation value A third image in which the remaining one display element is displayed in a checkered pattern in a display state corresponding to a gradation value for realizing a luminance of ½ of the maximum luminance, and in each dot A fourth image in which the R display element, the G display element, and the B display element are in a display state corresponding to a gradation value for realizing a luminance of 3/4 of the maximum luminance is displayed adjacently on the display device. checked by visual inspection whether the boundary is viewed between the third image and the fourth image γ characteristic test wherein the door. If the boundary is visible between the third image and the fourth image, gamma characteristics inspection method according to claim 1, wherein the boundary to change the settings of the driving device for a display device so that it no longer is visible. The first image and the second image that are adjacent, the third image and the fourth image and γ characteristic inspection method according to claim 1 or claim 2 displaying a test image on a display device comprising adjacent. Display in which dots in which R display elements that are display elements for displaying red, G display elements that are display elements for displaying green, and B display elements that are display elements for displaying blue are combined are arranged in a matrix A gamma characteristic inspection method for an apparatus,
  Within one dot, only one of the R, G, and B display elements is displayed according to the maximum gradation value, and the other two display elements are displayed according to the minimum gradation value. And the two display elements among the R display element, the G display element, and the B display element within one dot are set in a display state corresponding to the maximum gradation value, and the remaining one display element is set to the minimum gradation value. The first image in which the display state corresponding to the first display is arranged in a checkered pattern, and the R display element, the G display element, and the B display element in each dot have a luminance that is ½ of the maximum luminance. A second image having a display state corresponding to the gradation value for display is displayed adjacent to the display device, and whether or not a boundary is visually recognized between the first image and the second image is visually checked. Judge with
After determining that no boundary is visible between the first image and the second image,
Only one display element among the R display element, the G display element, and the B display element within one dot is displayed as the other two display states according to the gradation value for realizing the luminance of ½ of the maximum luminance. Display in which the display element is in a display state corresponding to the minimum gradation value, and the two display elements among the R display element, the G display element, and the B display element within one dot have a luminance that is ½ of the maximum luminance. A fifth image in which a display in which the remaining one display element is in a display state in accordance with the minimum gradation value as a display state in accordance with the gradation value to be realized is arranged in a checkered pattern, The R display element, the G display element, and the B display element are displayed on the display device adjacent to the sixth image in which the display state corresponding to the gradation value for realizing the luminance of ¼ of the maximum luminance is provided. , Visually determine whether a boundary is visually recognized between the fifth image and the sixth image
The gamma characteristic inspection method characterized by the above-mentioned. The γ characteristic inspection method according to claim 4 , wherein when a boundary is visually recognized between the fourth image and the fifth image, the setting of the driving device of the display device is changed so that the boundary is not visually recognized. The first image and the second image that are adjacent, fifth image and the sixth image and γ characteristic inspection method according to claim 4 or claim 5 to display the test image on the display device comprising of an adjacent.

Images