JP2007171029A - Inspection device, display simulation device and inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device capable of easily inspecting defects of a transparent plate product. <P>SOLUTION: The inspection device comprises a pair of polarizers 1, 2 arranged sandwiching an object to be inspected of a transparent plate product 15, a white light illumination source 4 illuminating the object 15 through the polarizer 1, a wide band phase shifter 3 arranged between the polarizer 1 and the object 15, a detection means 8 for detecting a transmission light that is irradiated from the other polarizer 2 by irradiation of illumination light from the light source 4, a filtering means 20 arranged between the polarizer 2 and the detection means 8, and an operation means for calculating an evaluation value from transmission data detected by the detection means 8 by wavelength-dispersion of the filtering means 20 and individually controlling an angle θ1 of the optical axis of the polarizer 1 and an angle θ2 of the optical axis of the phase shifter 3 in a direction of increasing the evaluation value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inspection apparatus, a display device simulation apparatus, and an inspection method for inspecting defects in transparent flat products such as optical films and liquid crystal panels.

  Polarized light output from a liquid crystal panel which is an example of a display device is determined by a Stokes parameter indicating a polarization state of light from a light source incident on the liquid crystal panel and a Mueller matrix unique to the liquid crystal panel. A liquid crystal panel can have a plurality of Mueller matrices by controlling a voltage applied to electrodes sandwiching a liquid crystal phase.

  If you want to know what kind of output can be obtained by pasting a prototype phase difference film on the surface of a liquid crystal panel with a certain Mueller matrix, use the phase difference on the surface of the liquid crystal panel. In this state, the voltage applied to the liquid crystal panel is controlled to give the liquid crystal panel a desired Mueller matrix, and then the light output from the phase difference film is observed. .

  However, the Mueller matrix that a liquid crystal panel can have is limited, and not all polarized light can be generated, so if you want to evaluate a liquid crystal panel with various characteristics, prepare all the liquid crystal panels. This will increase the cost of evaluation. On the other hand, a Babinet Soleil compensator, a λ / 4 phase shifter, and a λ / 2 phase shifter are arranged on the optical surface plate, and the polarized light is incident on them, and the position of the crystal plate of the Babinet Soleil compensation plate and the λ / 4 phase By controlling the positions of the child and the λ / 2 phase shifter, it is possible to output all polarized light. By utilizing this, it is possible to output arbitrary polarized light. Therefore, a liquid crystal panel having arbitrary characteristics can be simulated, and a phase difference film can be evaluated without using an actual liquid crystal panel for liquid crystal panels having various characteristics.

  The display device simulation apparatus described in Patent Document 1 below divides an optical path for each wavelength, adjusts a polarization state in each optical path, and then synthesizes light again in order to cope with chromatic dispersion. In each optical path, λ / 2 and λ / 4 phase shifters are inserted, and they correspond to an arbitrary polarization state by manipulating their relative optical axis angles.

  In addition, liquid crystal modules are prepared, and it is possible to cope with wavelength dispersion by spatially mixing colors.

JP 2005-274659 A

  However, in the display device simulation apparatus described in Patent Document 1, not only the trouble of branching and synthesizing the optical path, such as the necessity to prepare a phase shifter for each optical path, but also the quality of the polarization state accompanying the synthesis of light. There was a problem of deterioration. In addition, when a liquid crystal module is prepared and space color mixing is performed, there is a difficulty in preparing the liquid crystal module.

  In addition, optical films such as optical compensation films that are attached to liquid crystal screens and the like to improve the viewing angle, and the liquid crystal panel itself, the human being sees the light that has passed through them, so the film to be inspected (optical film), liquid crystal panel, etc. There is also a high demand that the inspector actually inspects the flat plate-shaped transparent product visually.

  The objective of this invention is providing the inspection apparatus which can perform the defect inspection of a transparent flat plate product easily.

  The inspection apparatus of the present invention includes a pair of polarizers arranged with a flat transparent product to be inspected, a white illumination light source that illuminates the inspection object through one of the polarizers, the one polarizer, and the A broadband phaser arranged between the object to be inspected, a detection means for detecting transmitted light emitted from the other polarizer of the pair of polarizers when illuminated with illumination light from the white illumination light source, and the other polarized light An evaluation value is calculated from the filter means disposed between the detector and the detection means, and each transmitted light data that is wavelength-dispersed by the filter means and detected by the detection means, and the evaluation value is directed in a predetermined direction. In this manner, the optical system includes an arithmetic unit that independently controls an angle of an optical axis of the one polarizer and an angle of an optical axis of the broadband phaser.

  The inspection apparatus according to the present invention is characterized in that the inspection object includes a transparent substrate and a liquid crystal sandwiched between the transparent substrates.

  The inspection apparatus according to the present invention is characterized in that the inspection object is an optical film.

  The inspection apparatus of the present invention includes means for ranking the inspection object using a detection value of the detection means when the control is completed.

  The inspection apparatus according to the present invention is characterized in that the detected value is transmitted light image data of the inspection object wavelength-dispersed by the filter means.

  In the inspection apparatus of the present invention, a lens for collecting the transmitted light emitted from the other polarizer and a screen for projecting the transmitted light from the lens are arranged between the other polarizer and the filter means. The detecting means detects the image projected on the screen through the filter means.

  The inspection apparatus of the present invention is characterized in that the lens is a lens capable of enlarging / reducing a projected image on the screen.

  The evaluation value of the inspection apparatus of the present invention is a luminance difference between a high luminance part and a low luminance part of the transmitted light.

  The arithmetic means of the inspection apparatus according to the present invention is characterized in that the control is advanced in a direction in which the luminance difference is increased by human visual sensitivity based on the human visual sensitivity data.

  The calculation means of the inspection apparatus of the present invention is characterized in that the control is advanced so that the average luminance of the inspection object or the luminance of the low luminance portion is minimized.

  The calculation means of the inspection apparatus of the present invention is configured so that the luminance of the low luminance part to be inspected becomes a specified luminance, or the difference between the luminance of the low luminance part and the specified luminance is minimized. Control is advanced.

  The calculation means of the inspection apparatus according to the present invention is configured so that the tristimulus value of the low luminance part to be inspected becomes a specified tristimulus value, or between the tristimulus value of the low luminance part and the specified tristimulus value. The control is advanced so as to minimize the difference.

  The inspection method of the present invention includes a pair of polarizers arranged with a flat transparent product to be inspected, a white illumination light source that illuminates the inspection object through one of the polarizers, the one polarizer, and the A broadband phaser arranged between the object to be inspected, a detection means for detecting transmitted light emitted from the other polarizer of the pair of polarizers when illuminated with illumination light from the white illumination light source, and the other polarized light In the inspection method of the inspection apparatus comprising a child and a filter means disposed between the detection means, an evaluation value is obtained from each transmitted light data that is wavelength-dispersed by the filter means and detected by the detection means, The angle of the optical axis of the one polarizer and the angle of the optical axis of the broadband retarder are independently controlled so that the evaluation value is directed in a predetermined direction, and the detection means detects when the control is completed. Shi Characterized in that said performing ranking of the test object on the basis of the inspection target image.

  The inspection method of the present invention includes a pair of polarizers arranged with a flat transparent product to be inspected, a white illumination light source that illuminates the inspection object through one of the polarizers, the one polarizer, and the A broadband phaser arranged between the object to be inspected, a detection means for detecting transmitted light emitted from the other polarizer of the pair of polarizers when illuminated with illumination light from the white illumination light source, and the other polarized light In the inspection method of the inspection apparatus comprising a child and a filter means disposed between the detection means, an evaluation value is obtained from each transmitted light data that is wavelength-dispersed by the filter means and detected by the detection means, The angle of the optical axis of the one polarizer and the angle of the optical axis of the broadband retarder are independently controlled so that the evaluation value is directed in a predetermined direction, and the detection means detects when the control is completed. Shi Characterized in that said determining the presence or absence of a defect of the inspection object based on the inspection target image.

  The display device simulating apparatus of the present invention includes a pair of polarizers arranged with a flat transparent product to be inspected, a white illumination light source that illuminates the inspection object through one of the polarizers, and the one A broadband phaser disposed between the polarizer and the inspection object; and a detection unit that detects transmitted light that is irradiated with illumination light from the white illumination light source and exits from the other polarizer of the pair of polarizers. A filter unit disposed between the other polarizer and the detection unit, and a calculation unit for each transmitted light data that is wavelength-dispersed by the filter unit and detected by the detection unit. The polarizer and the broadband phase shifter are freely rotated with respect to the polarizer on the detection means side in the optical path of the illumination light source to simulate a display device having a predetermined polarization state. A display device having the predetermined polarization state, the polarizer on the illumination light source side for obtaining the predetermined polarization state, and the polarizer on the detection means side of the broadband phase shifter Storage means for storing a table associated with the rotational positional relationship, and position control means for performing rotational position control of the polarizer and the broadband phase shifter on the illumination light source side. The rotation position of the polarizer and the broadband phase shifter on the illumination light source side is controlled based on the positional relationship corresponding to an arbitrary display device.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to detect the defect of a transparent flat plate product easily and reliably.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)

  FIG. 1 is a configuration diagram of an inspection apparatus according to the first embodiment of the present invention. Although the inspection apparatus of this embodiment inspects the optical compensation film as an inspection object in full color, it is not limited to this, and the defect inspection of other flat transparent products can be similarly performed.

  The inspection apparatus according to the present embodiment includes a pair of polarizers 1 and 2, a broadband λ / 4 film (λ / 4 broadband phase retarder) that is parallel to the polarizers 1 and 2 and placed between the polarizer 1 and the polarizer 2. 3), a halogen fiber illuminating device 4 which is a white illumination light source arranged outside the polarizer 1, and a parallel light irradiating means 5 which makes the light from the halogen fiber illuminating device 4 parallel light and enters the polarizer 1 And a lens 6 for condensing the light incident on the polarizer 1 from the halogen fiber illumination device 4 and emitted from the polarizer 2, and a screen 7 on which light transmitted through the lens 6 is projected.

  The inspection apparatus according to the present embodiment further includes a detection unit 8 that is installed on the back surface of the screen 7 and detects an image projected on the screen 7, and a filter unit that is disposed between the screen 7 and the detection unit 8. The color filter 20 as an example, the memory 9 storing human visibility data, the arithmetic unit 10 that advances control based on the detection value of the detection unit 8 as described later, and the evaluation value obtained by the arithmetic unit 10 Based on the rotation angle θ1 of the optical axis of the polarizer 1 (rotation angle in a plane perpendicular to the optical axis of the illumination light) and the rotation angle θ2 of the optical axis of the broadband λ / 4 film (λ / 4 broadband phaser) 3 And a rotation driving device 11 for driving (a rotation angle in a plane perpendicular to the optical axis of the illumination light). As the detection means 8, in this embodiment, a two-dimensional luminance meter is used, but is not limited to this.

  The λ / 4 broadband phase shifter 3 has optical characteristics as shown in FIG. 2 for visible light having a wavelength of about 400 to 800 nm. That is, the phase difference is 120 nm for red light (R light) with a wavelength of 610 nm, the phase difference is 151 nm for green light (G light) with a wavelength of 540 nm, and the phase difference is 159 nm for blue light (B light) with a wavelength of 400 nm. have.

  The color filter 20 includes three R interference filters that transmit only red light (R light), G interference filters that transmit only green light (G light), and B interference filters that transmit only blue light (B light). The projected image projected on the screen 7 is red according to the color filter 20 (R interference filter, G interference filter, or B interference filter) disposed in front of the detection means 8 (polarizer 2 side), Green or blue is detected by the detection means 8. The color filter 20 may be incorporated in the detection unit 8.

  In the inspection apparatus of the present embodiment, the film 15 to be inspected is inserted between the broadband λ / 4 film 3 and the polarizer 2 to perform defect inspection, but the film surface of the film 15 to be inspected is polarizers 1 and 2. Or arranged parallel to the surface of the broadband λ / 4 film 3. The in-plane optical axis of the film 15 to be inspected intersects with the transmission axis of the polarizer 2 at 45 °, and the lens 6 is positioned so that the transmitted light is focused on the film 15 to be inspected. The

  The film surface of the film 15 to be inspected can be changed to an arbitrary angle, and the film 15 can be inspected from an arbitrary viewing angle. Further, when the illumination light incident on the polarizer 1 is originally linearly polarized, the polarizer 1 arranged on the illuminated side may be replaced with a λ / 2 broadband phase shifter. In order for the illumination light to have a uniform polarization on the film surface of the film to be inspected 15, the illumination light is preferably parallel light instead of diffused light. In this embodiment, the parallel light irradiation means 5 is used. Although parallel light is used, any specific means for making parallel light may be used. Thus, by using parallel light as illumination light, the viewing angle dependency depending on the arrangement position of the detection means 8 is reduced, and an effect that the luminance signal in the illumination area can be made uniform is also obtained.

  In the inspection apparatus of the present embodiment, parallel illumination light is incident on the inspected film 15 through the polarizer 1 and the broadband phase retarder (wideband λ / 4 film) 3, and the transmitted light of the inspected film 15 is converted into the polarizer 2. , And is collected by the lens 6 and projected onto the screen 7. This projection image is detected by the detection means 8 via the color filter 20 (R interference filter, G interference filter, or B interference filter), and detection data is output to the arithmetic unit 10.

  The arithmetic device 10 calculates an evaluation value using the detection data. In this embodiment, the luminance difference between the high luminance portion and the low luminance portion in the detection data is calculated as the evaluation value. This luminance difference changes when the rotation angle θ1 of the optical axis of the polarizer 1 is changed, and also changes when the rotation angle θ2 of the optical axis of the broadband λ / 4 film 3 is changed. For this reason, the arithmetic unit 10 controls θ1 and θ2 independently, advances this control in the direction in which the evaluation value (luminance difference) increases, and when the control ends (the luminance difference no longer increases). The evaluation value at the time) is set as the evaluation value of the film 15 to be inspected.

  In order to obtain such an evaluation value, the arithmetic unit 10 identifies the background luminance Yb and the luminance portion different from the background luminance Yb, that is, the luminance Yo of the defective portion. Then, when ΔY = | Yb−Yo | and ΔYmin is a luminance difference discrimination threshold with respect to Yb, C = ΔY / Yb is larger than Cmin = ΔYmin / Yb, and C becomes the maximum value. The optical axis angle θ1 of the polarizer 1 and the optical axis angle θ2 of the broadband λ / 4 film 3 are controlled.

  The computing device 10 performs computation using human visibility data when computing θ1 and θ2. The reason why the arithmetic device 10 of this embodiment uses human visibility data is as follows.

  The detection means 8 is composed of a CCD type image sensor or a CMOS type image sensor. The sensitivity of these image sensors is different from the sensitivity that can be detected by human eyes. For example, as described on page 54 of “New Color Chemistry Handbook 2nd Edition” edited by the Japan Society of Color Science, the University of Tokyo, the human eye has a luminance difference that can be distinguished from the background luminance. It depends on the size. For this reason, when the inspector views the projected image, that is, the luminance image of the film to be inspected 15 on the back side of the screen 7, the values of θ1 and θ2 that can easily determine whether there is a defect are the sensitivity of the human eye. This is because it is necessary to control the optimum value in accordance with the above.

Next, details of the arithmetic processing performed by the arithmetic device 10 will be described.
(1) When the brightness on the screen 7 on which the inspected film 15 is set and the transmitted light is projected is measured by the detection means 8, the arithmetic unit 10 determines the low brightness portion excluding the high brightness portion (defective portion). The average luminance is set as the background luminance Yb1, and the luminance difference ΔY1 from the defective portion is obtained. Then, assuming that the origin of the angle θ of the polarizer 1 is θ1, and the origin of the angle θ of the broadband λ / 4 film 3 is θ2, the background luminance Yb1 and the luminance difference ΔY1 are obtained. A brightness difference discrimination threshold value ΔY1min is obtained from data of brightness difference ΔY with respect to background brightness Yb of human visibility data stored in advance in memory 9 in the computer, and Z1 = ΔY1−ΔY1min is calculated.

  (2) Next, the angle θ of the polarizer 1 is changed by + 4 ° to be θ1, and the origin of the angle θ of the broadband λ / 4 film 3 is θ2, and the background luminance Yb2 and the luminance difference ΔY2 are obtained. Then, it changes -2 degree and returns to the above-mentioned (1) state. Similarly to (1), a luminance difference discrimination threshold ΔY2min is obtained from ΔY data for the background luminance Yb2 stored in advance in a memory in the computer, and Z2 = ΔY2−ΔY2min is calculated.

  (3) Next, the angle θ1 of the polarizer 1 is changed by + 2 ° to θ1, the angle θ of the broadband λ / 4 film 3 is changed by + 4 ° to θ2, and the background luminance Yb3 and the luminance difference ΔY3 are obtained. Similarly to (1), the luminance difference discrimination threshold ΔY3min is obtained from ΔY data for the background luminance Yb3 stored in advance in the memory in the computer, and thereafter, the state is returned to the state (1) and Z3 = ΔY3−ΔY3min is calculated. .

  (4) From the above (1), (2) and (3), considering the three-dimensional notation of θ1 for the X-axis, θ2 for the Y-axis, and Z for the Z-axis, it is as follows. The conditions (1), (2), and (3) are compared to obtain max {Z1, Z2, Z3}. For example, if the maximum value is Z1, the conditions of θ1 and θ2 in (2) and (3) are determined. Symmetrically, the conditions of θ1 and θ2 in (1) are turned back to be the condition of (4).

  Similarly, the conditions of (2), (3), and (4) are compared to find max {Z2, Z3, Z4}. For example, if the maximum value is Z3, then θ1 and θ2 of (2) and (4) The conditions are symmetrical, and θ1 and θ2 in (3) are turned back to obtain condition (5). FIG. 3 schematically shows this. Thereafter, the same procedure is returned to calculate the luminance difference discrimination threshold ΔYmin with respect to the background luminance Yb, and the maximum value of the difference | Yo−Yb | between the defect luminance and the background luminance larger than ΔYmin is searched. That is, the optimum angles θ1 and θ2 of the polarizer 1 and the broadband λ / 4 film 3 are determined.

  As a result, when the inspector visually observes the inspection target film 15, θ1 and θ2 that are suitable for human visual sensitivity are controlled. Therefore, the inspector looks at the screen 7 to check whether there is a defect in the film 15. You can check it with your own eyes.

  The arithmetic unit 10 can also determine that the inspected film 15 is a defective film if there is a luminance portion of | Yo−Yb |> ΔYmin, and if it does not exist, determine that the film is a non-defective film. Can do.

  In the above example, the angle step of θ is 4 °, but the present invention is not limited to this. Usually, a method of converging at a large value and reducing the step as the number of iterations increases is desirable.

  The simplex method, which is one of such steepest descent methods, is described, for example, in the document ““ Data Processing Techniques in Scientific Measurement ”, supervised by Shigeo Minami, written by Yutaka Kawada, P138-151”.

  An example of this is the simplex method, but other optimization techniques may be used. For example, Newton-Raphson method, Monte Carlo method, simulated annealing method, Jacobi method and the like. Further, when it is desired to reliably obtain the true optimum value, it is more desirable to obtain the optimum value by changing all the variables even if the optimization time is somewhat long.

  For example, the polarization state that can be generated by a combination of a polarizer and a broadband phaser can be calculated by the following (Equation 1).

here,
α1: inclination angle of the phase advance axis relative to the ground.
α2: inclination angle of the polarizer transmission axis with respect to the ground.
δ: Phase difference of phase shifter.
Specifically, since the phase difference with respect to red light (R light) with a wavelength of 610 nm is 120 nm, δred = 2π × 120/610, and the phase difference with respect to green light (G light) with a wavelength of 540 nm is 151 nm, so δgreen = 2π. Since the phase difference with respect to blue light (B light) with × 151/540 and wavelength of 440 nm is 159 nm, δblue = 2π × 159/440.

  Since the phase difference δ (δred, δgreen, δblue) of the phase shifter and the incident polarization state are fixed, if the tilt angle α1 with respect to the ground of the phase advance phase axis and the tilt angle α2 with respect to the ground of the polarizer transmission axis are designated, The polarization state of light can be adjusted.

  The polarization state that can be generated by the combination of the azimuth angle of the linearly polarized light after passing through the polarizer and the phase difference fast axis is expressed by, for example, (Formula 2) for a wavelength of 440 nm (blue light (B light)). . The polarization states of the wavelength 610 nm (red light (R light)) and the wavelength 540 nm (green light (G light)) are also expressed in the same manner.

  In (Expression 2), the polarization state reproducible by the combination of a and b is illustrated as a Poincare sphere shown in FIG. As shown in FIG. 4, any polarized light can be generated outside the circularly polarized region. In the Poincare sphere shown in FIG. 4, the white area at the extreme portion indicates a high luminance area. In the unevenness inspection of the inspection target film 15, a high luminance region is not necessary. In the present invention, a region near the equator portion of the Poincare sphere that is substantially required is polarized using the polarizer 1 and the broadband phase shifter 3. .

  Therefore, the polarization state for each of the R, G, and B filters emitted from the liquid crystal panel is measured in advance, and the measured polarization state of blue light (B light) is determined based on (Equation 2) as the polarizer 1 and the broadband phase shifter. 3 is reproduced by rotating the optical axis 3 in the vertical plane of parallel light. By irradiating the inspection target film 15 with the reproduced light, the light transmitted through the inspection target film 15 and the polarizer 2 is projected onto the screen 7 to form an image. This image is detected by the detection means 8 through the B interference filter (color filter 20), and the luminance distribution is measured.

Similarly, the luminance distribution is measured for red light (R light) and green light (G light). The obtained three luminance distribution data (R, G, B luminance distribution data) are weighted according to the following expression in the arithmetic unit 10 according to the following formula: full color luminance unevenness distribution image = A1 × R luminance distribution + A2 × G luminance distribution + A3 × B luminance distribution By adding them, the color when the inspection object film 15 is used can be observed and evaluated in full color. However, A1, A2, and A3 are weighting factors.

As described above, in the inspection apparatus according to the present embodiment, the evaluation value for each inspection target film 15 (evaluation value when the control of θ1 and θ2 is completed) is obtained. Accordingly, it is preferable to rank the inspection target film and output the rank, and the inspector can perform a visual inspection with reference to this rank. Further, when the evaluation value is out of the predetermined value range, the inspection target film may be determined as a defective product and a determination result may be output. Further, after the control, a quantitative value is calculated from the newly detected two-dimensional luminance data by using a method as described in Japanese Patent Application No. 2004-249830 (method of the second embodiment below), The film to be inspected can be ranked according to the magnitude of the value.
(Second Embodiment)

  Since the basic configuration of the inspection apparatus of the present embodiment is the same as that of FIG. 1, description thereof is omitted. In the present embodiment, a color image capturing image sensor is used as the detection unit 8, and a light source is used. A white light source is used as 4. FIG. 5 is a functional block diagram of the arithmetic device 10 of the present embodiment. The arithmetic device 10 includes an image input unit 10a, an image data conversion unit 10b, a visual characteristic adaptation unit 10c, and an image quality evaluation value calculation unit. 10d.

  The image input unit 10a reads the detection data output from the detection means 8, that is, the two-dimensional color image data projected on the screen 7, and the image data conversion unit 10b converts the two-dimensional color image data into stimulus value data in the opposite color space. The visual characteristic matching unit 10c performs Fourier transform on the stimulus value data to obtain a power spectrum, superimposes a function representing human visual characteristics on the power spectrum, and further performs inverse Fourier transform. The image quality evaluation value calculation unit 10d operates to obtain an image quality evaluation value based on the stimulus value data.

  FIG. 6 is a diagram showing examples of streaks and unevenness observed when the inspected film 15 is a defective product. In the example shown in the figure, three examples are shown. When these streaks and unevenness appear in the projected image on the screen 7, the image quality is quantitatively evaluated. As the streaks and unevenness, there are one streak in FIG. 6A, periodic unevenness in FIG. 6B, random unevenness in FIG.

  FIG. 7 is a flowchart illustrating a processing procedure of image quality quantitative evaluation according to the present embodiment. First, the image input unit 10a takes in the detection data (two-dimensional RGB image data) output from the detection means 8 (step S11), and sends the two-dimensional RGB image data to the image data conversion unit 10b. The two-dimensional RGB image data including streaks and unevenness is read by the image input unit 10a, and then converted into a density level by A / D conversion, and a digital value image composed of information on the density value and the spatial position. Data (red density value R, green density value G, blue density value B, etc.) is sent to the image data converter 10b.

  Next, the image data conversion unit 10b performs matrix conversion from the digitized image data based on the characteristic parameters stored in advance according to the following (Equation 3) and converts them into tristimulus values (step) S12). More specifically, the image data is converted into tristimulus values (X, Y, Z) based on the relationship between the color characteristic values (R, G, B) of the image data and the standardized screen brightness. Here, K in (Equation 3) is a conversion matrix.

  The image information of the color image includes density information and chromaticity information. In the image evaluation of streaks and unevenness, only the density information is mainly used, but in the image quality quantitative evaluation of the present embodiment, the image is evaluated also using the chromaticity information. However, human visual characteristics are different for each color, and it is not possible to evaluate each color component centrally. Therefore, human visual characteristics for each color are evaluated by filtering correction for each color component of the image.

  Further, in the present embodiment, by processing using the opposite color space, a result that corresponds well to human subjective evaluation can be obtained. Specifically, the tristimulus values (X 1, Y 2, Z) obtained by (Equation 3) are converted into 3 sets (White-Black (K), Red-Green, Blue-Yellow) by matrix calculation using (Equation 4). ) To the stimulus value in the opposite color space (step S13).

  Next, the main appearance direction of stripes and unevenness is set. FIG. 8 is an explanatory diagram schematically showing how the appearance direction of streaks and unevenness at the spatial position of the opposite color stimulus value data is determined. The specific direction indicating the appearance direction of the stripes and unevenness is set as follows.

  First, as shown in FIG. 8, the captured two-dimensional image data 21 is added (projected) along a plurality of directions set at predetermined angles from an arbitrary direction of the image, and a plurality of one-dimensional profiles 23a, 23b, 23c,... Then, the direction in which the difference δ between the maximum value and the minimum value of the one-dimensional profile is maximized is set as a specific direction. One-dimensional averaging (step S14) for projecting such pixels is performed at high speed by image processing.

  That is, a process of rotating the two-dimensional RGB image data 21 captured by the detection unit 8 at a predetermined angle θ on a plane and a process of projecting each pixel value in a predetermined direction are performed. The direction of appearance of the unevenness is automatically detected. The setting of the specific direction may be obtained using the stimulus value in the opposite color space other than the two-dimensional RGB image data 21.

  Next, the one-dimensional stimulus value data profile 25a converted into stimulus values (W / K, R / G, B / Y) in the opposite color space by (Equation 4) and added (projected) along the specific direction. , 25b, 25c,... (See FIG. 9), one-dimensional Fourier transform is performed, and the power spectrum of the Fourier transform result is calculated to obtain the spatial frequency distribution.

  FIG. 9 is an explanatory diagram showing the one-dimensional stimulus value data profile projected in a specific direction corresponding to the streaks, irregularities (a), (b), and (c) of FIG. In the following description, the W / K channel data will be described as a representative, but the same processing is performed for the R / G and B / Y channels. FIG. 10 is an explanatory diagram showing the power spectrum after Fourier transform for the one-dimensional stimulus value data profile shown in FIG. 9 corresponding to the streaks, irregularities (a), (b), and (c) of FIG. .

  By performing Fourier transform on the one-dimensional stimulus value data profiles 25a, 25b, 25c,..., Power spectra 27a, 27b, 27c,... Showing intensity distributions for each frequency component are obtained as shown in FIG. Step S15). Then, filtering correction is performed on the power spectrum obtained in step S15 using spatial frequency characteristics (MTF) adapted to human visual characteristics (step S16). There are various methods for Fourier transform, but here, FFT (Fast Fourier Transform) is used to simplify the calculation.

  FIG. 11 is an explanatory view showing the MTF of visual characteristics, wherein the bandpass shape of the W / K channel is shown in (a), and the lowpass shapes of the R / G and B / Y channels are shown in (b).

  That is, the visual characteristic matching unit 10c performs filtering correction that superimposes the MTF characteristics 29a, 29b,... Corresponding to the observation conditions on the power spectrum of the image to be evaluated obtained by Fourier transform. As a result, as shown in FIG. 11, the frequency component that is highly sensitive to humans (about 0.4 cycle / mm is strong for the W / K component) is emphasized more, while the frequency with weak sensitivity is high. Attenuate components (especially high frequency components). For this reason, it can convert into the sensitivity of the spatial frequency component which matched human visual characteristics. Further, by preparing information on the MTF characteristics as described above for each observation condition in advance, an appropriate visual MTF filter corresponding to the actual observation condition can be appropriately selected to perform filtering correction, and correction processing is performed. The effect and reliability can be further increased.

  FIG. 12 is an explanatory diagram showing the Fourier spectrum after filtering corresponding to the streaks, irregularities (a), (b), and (c) of FIG. The spatial frequency distributions 31a, 31b, 31c,... After filtering processing shown in FIG. 12 obtained in this way are subjected to inverse Fourier transform, so that as shown in FIG. 33b, 33c,... Are obtained (step S17). FIG. 13 is an explanatory diagram showing the stimulus value data profile after inverse Fourier transform corresponding to the streaks, irregularities (a), (b), and (c) of FIG. In this way, the respective stimulus values for (W / K, R / G, B / Y) in the opposite color space are recombined.

  As a result, in the one-dimensional profile after the inverse Fourier transform, the steep shape of one streak is dulled in FIG. 13A in accordance with the visual characteristics, and the periodic unevenness in FIG. In the random unevenness of (c), the amplitude decreases.

  Next, an evaluation value is calculated by the image quality evaluation value calculation unit 10d from the result obtained by inverse Fourier transform (step S18). The image quality evaluation value calculation unit 10d schematically shows each stimulus value (W / Ki, R / Gi, B / Yi) at the position (i) of each one-dimensional stimulus value data profile returned in step S17. A difference value representing a distance from an average value (W / KAV, R / GAV, B / YAV) of the entire stimulus value data profile is obtained, and a value based on the difference value for all positions of the one-dimensional stimulus value data profile is obtained. The sum is obtained as an image quality evaluation value. The image quality evaluation value Ev serving as a quantitative evaluation value for such streaks and unevenness can be specifically calculated by the following (Equation 5).

  The image quality evaluation value Ev is expressed as the sum of products of the weights fi and | ΔXi | (i is an index representing an axial position orthogonal to the projection direction of the captured image). Note that | ΔXi | is expressed by (Equation 6), and fi is expressed by (Equation 7). When determining the quality of streaks and unevenness, observe only the region where the streaks and unevenness occur. It is a weighting coefficient formulated based on the hypothesis that

  Here, a description will be given with reference to FIG. There are three stimulus values (W / Ki, R / Gi, B / Yi) as the stimulus values of the opposite color for the one-dimensional position i obtained in step S17 described above. An average value (W / KAV, R / GAV, B / YAV) is obtained for each of these three stimulus values, and an opposite color stimulus value (W / Ki, R / Gi, B / Yi) at each position i is obtained. Difference values (W / Ki−W / KAV), (R / Gi−R / GAV), (B / Yi−B /) from the average values (W / KAV, R / GAV, B / YAV) corresponding thereto. YAV) is obtained for each of the three stimulus values, and | ΔXi | is obtained by obtaining the square root of the sum of squares of these difference values based on (Equation 6). Further, the weight fi is a value proportional to the distance from the average value of | ΔXi |, as shown in (Expression 7), and is normalized so that Σfi = 1.

  Therefore, the evaluation value Ev is the total of the brightness information (W / K) and the color difference information (R / G, B / Y) of the two-dimensional color image data detected by the detection means 8 for each of the three types of stimulus values. Each distance from the average value is obtained, and the square root of the sum of squares for these distances is multiplied by the weight fi to obtain the sum.

  Therefore, according to the above-mentioned quantitative evaluation of the image quality, by converting into the opposite color space and considering the color difference information, the modulation processing according to the human visual characteristic is performed more accurately, and the streak and unevenness are unified. It can be quantitatively evaluated.

  Further, since the projection process for the two-dimensional color image data picked up by the detecting means 8 is carried out by rotating at a predetermined angle θ, the direction of streaks and unevenness occurring in an unspecified direction of the inspection target film 15 is automatically set. Can be identified.

Furthermore, the two-dimensional color image data picked up by the detection means 8 is converted into the opposite color space (image data conversion step), and the visual characteristic adaptation step is performed after performing the projection processing in a specific direction. Can be processed in a one-dimensional state with a reduced amount of data, reducing the calculation burden and enabling higher-speed processing.
(Third embodiment)

  Next, another embodiment of the image quality quantitative evaluation of the second embodiment will be described as a third embodiment. In this embodiment, the stimulus value in the opposite color space is obtained from the two-dimensional RGB image data imaged by the detection means 8, the visual characteristic adaptation process is performed with the two-dimensional data, and then the projection process to one dimension is performed. The image quality evaluation value is obtained.

  FIG. 15 is a flowchart showing an image quality quantitative evaluation procedure of the present embodiment, and FIG. 16 is an explanatory diagram schematically showing a visual characteristic adaptation process for two-dimensional stimulus value data.

  In the present embodiment, the image input unit 10a reads the two-dimensional RGB image data captured by the detection means 8 (step S21), and the two-dimensional image data (R, G, B) is read by the image data conversion unit 10b. Conversion to stimulus values (step S22), and conversion to stimulus value data (W / K, R / G, B / Y) in the opposite color space as shown in FIG. 16B (step S23).

  The converted stimulus value data (W / K, R / G, B / Y) in the opposite color space is two-dimensionally Fourier transformed by the visual characteristic matching unit 10c as shown in FIG. Power spectra 41a, 41b and 41c are obtained (step S24). Next, as shown in FIG. 16 (d), MTFs 43a, 43b, and 43c representing human visual characteristics are superimposed on the power spectra 41a, 41b, and 41c, respectively, and further two-dimensional Fourier inverse transform is performed. As a result, as shown in FIG. 16E, stimulus value data of the opposite color in which streaks and unevenness are modulated in accordance with the visual characteristics is obtained (step S26).

  In this embodiment, the one-dimensional averaging process shown in FIG. 16F is performed after the visual characteristic adaptation process shown in FIGS. 16C to 16E (step S27). In other words, streaks and unevenness are modulated in accordance with the visual characteristics with respect to the two-dimensional stimulus value data in the opposite color space, and then the projection process to one dimension is performed.

  The subsequent processing is the same as in the second embodiment, and the image quality evaluation value calculation unit 10d uses the difference value between the stimulus value at each position of the stimulus value data in the opposite color space and the average value of the entire stimulus value data. Are obtained for all the positions by multiplying these difference values by the weight function, and the sum is defined as an image quality evaluation value Ev.

  According to the image quality quantitative evaluation of the present embodiment, the detection means 8 captures an image as compared with the case where the visual characteristic adaptation processing is performed as it is with the two-dimensional data, and compared with the case where it is performed after the conversion into the one-dimensional data by the projection processing. Since the streaks and unevenness distributed in the two-dimensional image of the inspected film 15 are more accurately emphasized, the detection accuracy of the streaks and unevenness is improved. That is, since the projection processing is performed after the streak and unevenness are emphasized, the SN ratio of the projection result is improved and the separation of the stripes and the noise becomes easy.

  In addition, by taking the logarithmic value of the image quality evaluation value Ev obtained by each of the above-described embodiments and using this as a quantitative evaluation value, it becomes possible to further improve the linearity with human visual evaluation.

  Also, in the second and third embodiments, similarly to the first embodiment, it is preferable to rank the inspection objects according to the magnitude of the obtained evaluation value of the inspection object and output the result. When the evaluation value exceeds the predetermined value range, the result is preferably output as a defective product.

  Furthermore, in the second and third embodiments, white light is used as the light source 4 and the transmission color image data of the inspection object is used in the calculation processing. However, the same calculation processing may be performed using the monochromatic light source 4. .

  In the first embodiment, the illumination light from the halogen fiber illumination device 4 is parallel light. However, when the liquid crystal backlight is a parallel light source, even if partial polarization is generated from the liquid crystal panel, the background This contributes to an increase in luminance Yb and a decrease in C (= ΔY / Yb), so that there is no problem because defects are easily visible.

  Furthermore, it is more preferable to use a lens that can be enlarged or reduced as the lens 6 shown in FIG. By using a lens that can be enlarged or reduced, projection on the screen 7 corresponds to a region having good human eye sensitivity from the spatial frequency obtained from the two-dimensional luminance distribution of the film to be inspected and human visual sensitivity data. This is because the image can be enlarged or reduced.

(Fourth embodiment)
Next, a fourth embodiment according to the present invention will be described. FIG. 17 is a configuration diagram of an inspection apparatus (display device simulation apparatus) according to the fourth embodiment of the present invention. Although the inspection apparatus of this embodiment inspects the optical compensation film as an inspection object in full color, it is not limited to this, and the defect inspection of other flat transparent products can be similarly performed.

  The inspection apparatus according to the present embodiment includes a pair of polarizers 1 and 2, a broadband λ / 4 film (λ / 4 broadband phase retarder) that is parallel to the polarizers 1 and 2 and placed between the polarizer 1 and the polarizer 2. 3), a halogen fiber illuminating device 4 which is a white illumination light source arranged outside the polarizer 1, and a parallel light irradiating means 5 which makes the light from the halogen fiber illuminating device 4 parallel light and enters the polarizer 1 And a lens 6 for condensing the light incident on the polarizer 1 from the halogen fiber illumination device 4 and emitted from the polarizer 2, and a screen 7 on which light transmitted through the lens 6 is projected.

  The inspection apparatus according to the present embodiment further includes a detection unit 8 that is installed on the back surface of the screen 7 and detects an image projected on the screen 7, and a filter unit that is disposed between the screen 7 and the detection unit 8. A color filter 20 as an example; a storage unit 41 that functions as a storage unit that stores a table associated with the rotational positional relationship of the polarizer 1 and the broadband phase shifter 3 with respect to the polarizer 2 to obtain a predetermined polarization state; The computing device 10 that computes each transmitted light data that is wavelength-dispersed by the filter 20 and detected by the detecting means 8 as described later, and the optical axis of the polarizer 1 with reference to the storage unit 49 when a predetermined polarization state is designated. Rotation angle θ1 (rotation angle in a plane perpendicular to the optical axis of the illumination light) and rotation angle θ2 of the optical axis of the broadband λ / 4 film (λ / 4 broadband phaser) 3 (perpendicular to the optical axis of the illumination light) In the plane And a rotary driving device 11 for driving the rotation angle) and. As the detection means 8, in this embodiment, a two-dimensional luminance meter is used, but is not limited to this. The detection means 8 is connected to a calculation unit 42 that fetches detection data and executes calculation processing.

  The λ / 4 broadband phase shifter 3 has optical characteristics as shown in FIG. 2 for visible light having a wavelength of about 400 to 800 nm. That is, the phase difference is 120 nm for red light (R light) with a wavelength of 610 nm, the phase difference is 151 nm for green light (G light) with a wavelength of 540 nm, and the phase difference is 159 nm for blue light (B light) with a wavelength of 400 nm. have.

  The color filter 20 includes three R interference filters that transmit only red light (R light), G interference filters that transmit only green light (G light), and B interference filters that transmit only blue light (B light). The projected image projected on the screen 7 is red according to the color filter 20 (R interference filter, G interference filter, or B interference filter) disposed in front of the detection means 8 (polarizer 2 side), Green or blue is detected by the detection means 8. The color filter 20 may be incorporated in the detection unit 8.

  In the inspection apparatus of the present embodiment, the film 15 to be inspected is inserted between the broadband λ / 4 film 3 and the polarizer 2 to perform defect inspection, but the film surface of the film 15 to be inspected is polarizers 1 and 2. Or arranged parallel to the surface of the broadband λ / 4 film 3. The in-plane optical axis of the inspected film 15 is determined by the type of inspected film. For example, in the case of a TN WV film, the WV film optical axis coincides with the transmission axis of the polarizer 2, and in the case of a VA biaxial film, the biaxial film optical axis coincides with the transmission axis of the polarizer 2, and the OCB WV film. In this case, the optical axis of the support coincides with the transmission axis of the polarizer 2, and the position of the lens 6 is adjusted so that the transmitted light is focused on the film to be inspected 15.

  The film surface of the film 15 to be inspected can be changed to an arbitrary angle, and the film 15 can be inspected from an arbitrary viewing angle. In order for the illumination light to have a uniform polarization on the film surface of the film to be inspected 15, the illumination light is preferably parallel light instead of diffused light. In this embodiment, the parallel light irradiation means 5 is used. Although parallel light is used, any specific means for making parallel light may be used. Thus, by using parallel light as illumination light, the viewing angle dependency depending on the arrangement position of the detection means 8 is reduced, and an effect that the luminance signal in the illumination area can be made uniform is also obtained.

  In the inspection apparatus of the present embodiment, parallel illumination light is incident on the inspected film 15 through the polarizer 1 and the broadband phase retarder (wideband λ / 4 film) 3, and the transmitted light of the inspected film 15 is converted into the polarizer 2. , And is collected by the lens 6 and projected onto the screen 7. This projection image is detected by the detection means 8 via the color filter 20 (R interference filter, G interference filter, or B interference filter), and the detection data is output to the arithmetic unit 42.

  The calculation unit 42 integrates the transmitted light data detected through the three interference filters R, G, and B to obtain one transmitted light data.

  For example, the polarization state that can be generated by a combination of a polarizer and a broadband phaser can be calculated by the following (Equation 1).

here,
α1: inclination angle of the phase advance axis relative to the ground.
α2: inclination angle of the polarizer transmission axis with respect to the ground.
δ: Phase difference of phase shifter.
Specifically, since the phase difference with respect to red light (R light) with a wavelength of 610 nm is 120 nm, δred = 2π × 120/610, and the phase difference with respect to green light (G light) with a wavelength of 540 nm is 151 nm, so δgreen = 2π. Since the phase difference with respect to blue light (B light) with × 151/540 and wavelength of 440 nm is 159 nm, δblue = 2π × 159/440.

  Since the phase difference δ (δred, δgreen, δblue) of the phase shifter and the incident polarization state are fixed, if the tilt angle α1 with respect to the ground of the phase advance phase axis and the tilt angle α2 with respect to the ground of the polarizer transmission axis are designated, The polarization state of light can be adjusted.

  The polarization state that can be generated by the combination of the azimuth angle of the linearly polarized light after passing through the polarizer and the phase difference fast axis is expressed by, for example, (Formula 2) for a wavelength of 440 nm (blue light (B light)). . The polarization states of the wavelength 610 nm (red light (R light)) and the wavelength 540 nm (green light (G light)) are also expressed in the same manner.

  In (Expression 2), the polarization state reproducible by the combination of a and b is illustrated as a Poincare sphere shown in FIG. As shown in FIG. 4, any polarized light can be generated outside the circularly polarized region. In the Poincare sphere shown in FIG. 4, the white area at the extreme portion indicates a high luminance area. In the unevenness inspection of the inspection target film 15, a high luminance region is not necessary. In the present invention, a region near the equator portion of the Poincare sphere that is substantially required is polarized using the polarizer 1 and the broadband phase shifter 3. .

  Therefore, the polarization state for each of the R, G, and B filters emitted from the liquid crystal panel is measured in advance, and the measured polarization state of blue light (B light) is determined based on (Equation 2) as the polarizer 1 and the broadband phase shifter. 3 is reproduced by rotating the optical axis 3 in the vertical plane of parallel light. By irradiating the inspection target film 15 with the reproduced light, the light transmitted through the inspection target film 15 and the polarizer 2 is projected onto the screen 7 to form an image. This image is detected by the detection means 8 through the B interference filter (color filter 20), and the luminance distribution is measured.

Similarly, the luminance distribution is measured for red light (R light) and green light (G light). The obtained three luminance distribution data (R, G, B luminance distribution data) are weighted according to the following formula: full color luminance unevenness distribution image = A1 × R luminance distribution + A2 × G luminance distribution + A3 × B luminance distribution By adding the values, the color when the inspection object film 15 is used can be observed and evaluated in full color. However, A1, A2, and A3 are weighting factors.

  As described above, in the inspection apparatus according to the present embodiment, the inspector can visually inspect the optical film under a condition that optically simulates the state in which the optical film is mounted on the liquid crystal panel. Although the output polarization state of the liquid crystal panel differs for each of gradation signals from 0 to 255 such as white, gray, and black, it is possible to evaluate the film surface state in a state corresponding to each.

  Since the inspection apparatus according to the present invention can easily inspect defects in transparent objects, it is useful when applied to full-color inspection of retardation products, optical compensation films for improving viewing angle, display products such as liquid crystal panels, and the like. .

It is a lineblock diagram of the inspection device concerning a 1st embodiment of the present invention. It is a graph which shows the optical characteristic of a broadband phase shifter. It is explanatory drawing of the optimization method performed with the inspection apparatus of FIG. It is a figure which shows the polarization state on a Poincare sphere. It is a functional block diagram of the arithmetic unit used with the test | inspection apparatus which concerns on the 2nd Embodiment of this invention. It is explanatory drawing showing the example of a stripe and nonuniformity to (a), (b), (c). It is a flowchart which shows the image quality quantitative evaluation procedure which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which showed typically a mode that the appearance direction of the stripe and the nonuniformity in the spatial position of opposite color stimulus value data was determined. It is explanatory drawing which represented the one-dimensional irritation | stimulation value data profile projected in the specific direction corresponding to the stripe, nonuniformity (a), (b), (c) of FIG. It is explanatory drawing which represented the power spectrum after the Fourier-transform with respect to the one-dimensional stimulus value data profile shown in FIG. 9 corresponding to the stripe, unevenness | corrugation (a), (b), (c) of FIG. FIG. 4 is an explanatory diagram showing the MTF of visual characteristics, where the band pass shape of the W / K channel is shown in (a), and the low pass shapes of the R / G and B / Y channels are shown in (b). It is explanatory drawing which represented the Fourier spectrum after filtering corresponding to the stripe, nonuniformity (a), (b), (c) of FIG. It is explanatory drawing which represented the one-dimensional irritation | stimulation value data profile after Fourier inverse transformation corresponding to the stripe, nonuniformity (a), (b), (c) of FIG. It is explanatory drawing which shows the distance from an average value (W / KAV, R / GAV, B / YAV) with respect to a stimulus value (W / Ki, R / Gi, B / Yi). It is a flowchart showing the image quality quantitative evaluation procedure which concerns on another embodiment of this invention. It is explanatory drawing which represents roughly the visual characteristic adaptation process with respect to two-dimensional stimulus value data. It is a block diagram of the inspection apparatus which concerns on the 4th Embodiment of this invention.

Explanation of symbols

1, 2 Polarizer 3 Broadband λ / 4 film (Broadband phaser)
4 Halogen fiber illuminator (white illumination light source)
Reference Signs List 5 Parallel light irradiation means 6 Condensing lens 7 Screen 8 Detection means 9 Memory 10 storing human visibility data 10 Arithmetic unit 11 Rotation drive unit 15 Inspection target (flat transparent product)
20 Color filter (filter means)
41 Storage unit 42 Calculation unit θ1 Angle of optical axis of polarizer θ2 Angle of optical axis of broadband phaser

Claims (17)

  A pair of polarizers arranged across a flat transparent product to be inspected, a white illumination light source that illuminates the inspection object through one of the polarizers, and an arrangement between the one polarizer and the inspection object A broad-band phase shifter, a detection means for detecting transmitted light that is irradiated with illumination light from the white illumination light source and emitted from the other polarizer of the pair of polarizers, and the other polarizer and the detection means An evaluation value is calculated from each of the transmitted light data detected by the detection means after being wavelength-dispersed by the filter means arranged between the filter means and the one polarizer so that the evaluation value is directed in a predetermined direction An inspection apparatus comprising: an arithmetic means for independently controlling the angle of the optical axis of the optical axis and the angle of the optical axis of the broadband phaser.   The inspection apparatus according to claim 1, wherein the inspection object includes a transparent substrate and a liquid crystal sandwiched between the transparent substrates.   2. The transparent object inspection apparatus according to claim 1, wherein the inspection object is an optical film.   The inspection apparatus according to any one of claims 1 to 3, further comprising a unit that ranks the inspection target using a detection value of the detection unit at the time when the control is completed.   The inspection apparatus according to claim 4, wherein the detection value is image data of the inspection object that is wavelength-dispersed by the filter unit.   A lens for condensing the transmitted light emitted from the other polarizer and a screen for projecting the transmitted light of the lens are disposed between the other polarizer and the filter means, and the detection means 6. The inspection apparatus according to claim 1, wherein an image projected on a screen is detected through the filter means.   The inspection apparatus according to claim 6, wherein the lens is a lens capable of enlarging / reducing a projected image on the screen.   The inspection apparatus according to claim 1, wherein the evaluation value is a luminance difference between a high luminance portion and a low luminance portion of the transmitted light.   The inspection apparatus according to claim 8, wherein the calculation unit advances the control in a direction in which the luminance difference increases with human visual sensitivity based on the human visual sensitivity data.   The inspection apparatus according to claim 8, wherein the calculation unit advances the control so that an average luminance of the inspection target or a luminance of the low-luminance portion is minimized.   The arithmetic means advances the control so that the luminance of the low-luminance portion of the inspection target becomes a designated luminance, or the difference between the luminance of the low-luminance portion and the designated luminance is minimized. The inspection apparatus according to any one of claims 8 to 10.   The calculation means is configured so that the tristimulus value of the low-luminance portion of the inspection target becomes a designated tristimulus value, or the difference between the tristimulus value of the low-luminance portion and the designated tristimulus value is minimized. The inspection apparatus according to claim 8, wherein the control is advanced.   A pair of polarizers arranged across a flat transparent product to be inspected, a white illumination light source that illuminates the inspection object through one of the polarizers, and an arrangement between the one polarizer and the inspection object A broad-band phase shifter, a detection means for detecting transmitted light that is irradiated with illumination light from the white illumination light source and emitted from the other polarizer of the pair of polarizers, and the other polarizer and the detection means In the inspection method of the inspection apparatus comprising the filter means disposed therebetween, an evaluation value is obtained from each transmitted light data that is wavelength-dispersed by the filter means and detected by the detection means, and the evaluation value is in a predetermined direction. The angle of the optical axis of the one polarizer and the angle of the optical axis of the broadband phaser are independently controlled so as to be directed to the Inspection method and performing ranking of the test object based on.   A pair of polarizers arranged across a flat transparent product to be inspected, a white illumination light source that illuminates the inspection object through one of the polarizers, and an arrangement between the one polarizer and the inspection object A broad-band phase shifter, a detection means for detecting transmitted light that is irradiated with illumination light from the white illumination light source and emitted from the other polarizer of the pair of polarizers, and the other polarizer and the detection means In the inspection method of the inspection apparatus comprising the filter means disposed therebetween, an evaluation value is obtained from each transmitted light data that is wavelength-dispersed by the filter means and detected by the detection means, and the evaluation value is in a predetermined direction. The angle of the optical axis of the one polarizer and the angle of the optical axis of the broadband phaser are independently controlled so as to be directed to the Inspection method characterized by determining the presence or absence of a defect of the inspection object based on. A pair of polarizers arranged across a flat transparent product to be inspected;
A white illumination light source that illuminates the inspection object through one of the polarizers;
A broadband phaser disposed between the one polarizer and the inspection object;
Detecting means for detecting transmitted light irradiated from the white illumination light source and coming out of the other polarizer of the pair of polarizers;
Filter means disposed between the other polarizer and the detection means;
Each of the transmitted light data is wavelength-dispersed by the filter means and detected by the detection means,
The display device for simulating a display device having a predetermined polarization state by freely rotating the polarizer and the broadband phase shifter on the illumination light source side with respect to the polarizer on the detection means side on the optical path of the illumination light source A simulation device,
A table associated with the display device having the predetermined polarization state, and the rotational positional relationship with respect to the polarizer on the illumination light source side and the polarizer on the detection means side of the broadband phase shifter for obtaining the predetermined polarization state Storage means for storing
A position control means for performing rotational position control of the polarizer on the illumination light source side and the broadband phase shifter;
The first-position control means controls the rotational positions of the polarizer and the broadband phaser on the illumination light source side based on the table so as to be in the positional relationship corresponding to an arbitrary display device. Display device simulation device.   The said calculating means is further equipped with the data integration means which integrates the some transmitted light data which the wavelength dispersion | distribution by the said filter means detected by the said detection means to one transmitted light data. Display device simulation device.   17. The display device simulating apparatus according to claim 15, wherein the inspection object is an optical film.

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