JP2004012256A - Pixel inspection device and pixel inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a pixel inspection device and a pixel inspection method that precisely inspect at least a defect of pixel even when the number of photoreceiving elements to one pixel of a display equipment to be inspected is small. <P>SOLUTION: This device of the present invention is an improved pixel inspection device wherein a desired inspection pattern is displayed on the display equipment to be inspected, wherein light from the pixel of the display equipment is detected by a plurality of photoreceiving elements, and wherein the defect of the pixel of the display equipment is inspected. This device is characterized in that it is provided with a shift correction means for correcting a brightness level from the photoreceiving element based on a positional relation of mapping between the pixel of the display equipment and the photoreceiving element, a brightness correcting means for correcting the brightness level corrected by the correction means based on a response characteristic of the light from the pixel of the display equipment to the photoreceivng element, and a judging means for judging the defect of the pixel based on the corrected brightness level corrected by the brightness correcting means and the inspection pattern. <P>COPYRIGHT: (C)2004,JPO

Description

【００５５】
ここで、Ａ_３３は、着目する受光素子ａ_３３の輝度レベルａｃ_３３を補正した後の輝度レベルである。また、Ｋｓ_ｉｊは、着目する受光素子ａ_３３を中心とする５行５列の２５個の受光素子ａ_ｉｊごとの補正係数である。このようにして、輝度レベルａｃ_ｉｊを補正して、輝度レベルＡ_ｉｊを求める。
【００５６】
但し、この補正係数Ｋｓ_ｉｊは、検査を行う前に、調整用の表示機器をずれ量Δｘ、Δｙが０となるように設定し求める。具体的には、受光素子ａ_３３に対応する画素のみを表示させ、受光素子ａ_ｉｊの輝度レベルａｐ_ｉｊ（＝ａｃ_ｉｊ）を求める。つまり、受光素子ａ_３３の輝度レべルＡ_３３のみ非ゼロの値であり、残りの受光素子ａ_１１〜ａ_１５、ａ_２１〜ａ_２５、ａ_３１、ａ_３２、ａ_３４、ａ_３５、ａ_４１〜ａ_４５、ａ_５１〜ａ_５５の輝度レベルＡ_１１〜Ａ_１５、Ａ_２１〜Ａ_２５、Ａ_３１、Ａ_３２、Ａ_３４、Ａ_３５、Ａ_４１〜Ａ_４５、Ａ_５１〜Ａ_５５は０となる。このようにして、２５個の連立方程式を作り、補正係数Ｋｓ_ｉｊを求める。また、平均的に効果があるように、より多くの方程式を連立させ、最小二乗法により補正係数Ｋｓ_ｉｊを求めてもよい。そして、求めた補正係数Ｋｓ_ｉｊを、補正係数記憶手段６２に格納しておく。
【００５７】
そして、判定手段６５が、式（３）によって補正した輝度レベルＡ_ｉｊと検査パターン出力部２０からの検査パターンとを比較して、画素の欠陥の有無を検査する（Ｓ１４）。例えば、（イ）全画素表示時に、補正した輝度レベルＡ_ｉｊが、所望の輝度レベルより低いと、その受光素子３１に対応する画素を欠陥と判定する。（ロ）全画素非表示時に、補正した輝度レベルＡ_ｉｊが、所望の輝度レベルよりも高いと、その受光素子３１に対応する画素を欠陥と判定する。（ハ）画素の輝度レベルを最大値の５０％に設定し、補正した輝度レベルＡ_ｉｊが、最大輝度レベルの５０％±ｑ％（ｑ：整数）の範囲に収まらないと、その受光素子３１に対応する画素を欠陥と判定する。
【００５８】
従来のように式（１）による補正方法の場合、ＰＳＦが点対称でないと、輝点や滅点の分布を精度良く補正することができず、さらに、画素の欠陥の数を正確に求めることができない。例えば、全画面非表示とし、ある１画素に非常に強い輝点欠陥があり、式（１）によって補正を行ったとしても、その画素に対応する受光素子のみでなく、隣接する受光素子にも一定量の輝度レベルが発生する。そして、その量が欠陥と判定する閾値よりも大きくなることがあり、実際は欠陥が１画素にもかかわらず、２画素連続した欠陥とみなされ、欠陥の画素数が１個多く検出され、精度よく検査することができない。
【００５９】
しかし、ずれ補正手段６３が、液晶ディスプレイ１０の画素とＣＣＤカメラ３０の受光素子３１との位置関係のずれによる輝度レベルａｐ_ｉｊの誤差を補正し、輝度補正手段５４が、応答特性に基づく補正係数で、ずれ補正手段６３が補正した輝度レベルａｃ_ｉｊの補正を行うので、１画素からの光を検出する受光素子３１の数が少なく、さらに光学系４０等の歪みによって、ＰＳＦが点対称でなく２次元的な分布であっても、輝度レベルＡ_ｉｊを精度よく求めることができる。これにより、被検査表示機器の１画素に対する受光素子数が少なくとも、液晶ディスプレイ１０の画素の欠陥を精度よく検査することができる。
【００６０】
続いて図４は、本発明の第２の実施例を示した構成図である。ここで、図１と同一のものは同一符号を付し、説明を省略すると共に図示も省略する。図４において、検査部６０に、ランク決定手段６６が設けられる。ランク決定手段６６は、判定手段６５が欠陥と判断した画素の配置により、液晶ディスプレイ１０の画素のランクを決定する。
【００６１】
このような装置の動作を説明する。ランク決定手段６６が、判定手段６５の判定結果から、欠陥画素の配置、例えば２画素以上連続して欠陥画素が配置されているのを検出したならば、不良品とランク付けする。そして、このランクを図示しない外部装置に出力する。このようなランク決定手段６６が、欠陥画素の配置によって、液晶ディスプレイのランク分けをする動作以外は、図１に示す装置と同様なので説明を省略する。
【００６２】
このように、ランク決定手段６６が、欠陥画素が連続しているかを判断するので、ユーザの視認性に沿った検査ができる。すなわちユーザは、欠陥画素が飛び飛びの不連続よりも、連続して存在するほうが、欠陥品と認識し易い。これにより、画素の欠陥が同一の数であっても、液晶ディスプレイ１０の画素のランクを正確に検査することができる。
【００６３】
続いて、図５は、本発明の第３の実施例を示した構成図である。ここで、図１と同一のものは同一符号を付し、説明を省略すると共に図示も省略する。図２において、光学系４０とＣＣＤカメラ３０の間にスクリーン７０が設けられる。このような装置は、図１に示す検査装置にスクリーン７０を設けることにより、液晶ディスプレイ１０が投射型であるプロジェクターに用いられる場合の検査に適した構成である。
【００６４】
図５に示す装置の動作を説明する。検査パターン出力部２０が、液晶ディスプレイ１０の各画素を所望の検査パターン、例えば、１ラインずつ順番に表示させたり、全画素を表示、非表示させたりする。
【００６５】
そして、光学系４０が、液晶ディスプレイ１０からの光を、スクリーン７０に所望の位置へ投影する。そして、ＣＣＤカメラ３０の各受光素子３１が、光学系４０のレンズ４１、スクリーン７０を介して、液晶ディスプレイ１０の各画素から出力された光を検出する。
【００６６】
また、液晶ディスプレイ１０の各画素からの光を、光学系４０が、スクリーン７０に投影し、このスクリーン７０に投影された光を、ＣＣＤカメラ３０が検出する以外の動作は、図１に示す装置と同様なので説明を省略する。もちろん、スクリーン７０を透過する光でなく、スクリーン７０で反射する光を、ＣＣＤカメラ３０が検出する構成でもよい。
【００６７】
なお、本発明はこれに限定されるものではなく、以下のようなものでもよい。
（１）図１、図４、図５に示す装置において、ずれ補正手段６３、輝度補正手段６４のそれぞれは、全受光素子３１からの輝度レベルを同じずれ量Δｘ、Δｙ、補正係数Ｋｓ_ｉｊで補正を行う構成を示したが、受光素子３１の位置によって、ずれ量Δｘ、Δｙ、補正係数Ｋｓ_ｉｊを変えてもよい。
【００６８】
例えば、受光素子３１を９つのエリアに分割し、この分割した位置ごとに、それぞれの補正係数Ｋｓ_ｉｊを用いて、式（２）、式（３）によって補正を行う。すなわち、液晶ディスプレイ１０の各画素からの光は光学系４０やスクリーン７０等を介してＣＣＤカメラ３０で検出されるが、レンズ４１、スクリーン７０の中心付近を通る光路と周辺部を通る光路では、写像の位置関係や、光の応答特性が異なることが多いからである。もちろん、分割するエリアの面積は、同面積でなく、例えば、中心部の面積を多くとってもよい。
【００６９】
このように、エリアごとに求めたずれ量Δｘ、Δｙ、補正係数Ｋｓ_ｉｊで各受光素子３１の輝度レベルを補正するので、画素からの光路によって生じる応答特性のばらつきを考慮して、より正確に輝度レベルを補正することができる。これにより、液晶ディスプレイ１０の画素の欠陥をより精度よく検査することができる。
【００７０】
（２）本発明の画素検査装置は、被検査表示機器を液晶ディスプレイ１０としたが、画素を電気的にコントロールする表示機器、例えば液晶パネル、プラズマディスプレイ、有機ＥＬディスプレイ、ＬＥＤディスプレイ等の画素の検査にも適用することができる。
【００７１】
（３）液晶ディスプレイ１０の１画素からの光を、１個の受光素子３１で検出する例を示したが、複数個の受光素子３１で検出するようにしてもよい。
【００７２】
（４）輝度補正手段６４が、着目した受光素子ａ_３３を含む２５個の受光素子ａ_ｉｊからの輝度レベルａｐ_ｉｊで補正を行ったが、この補正を行う受光素子ａ_ｉｊの数は、いくつでもよい。例えば、光学系４０等の歪みの大きい部分は、より多くの受光素子ａ_ｉｊを用いて、着目する受光素子ａ_３３の輝度レベルａｐ_３３の補正を行ってもよい。
【００７３】
（５）図４に示す装置において、ランク決定手段６６が、液晶ディスプレイ１０の画素の欠陥の配置を、全画素に対して検査を行ったが、ユーザが画素の欠陥を認識し易い液晶ディスプレイ１０の中心付近の画素だけを対象に検査してランク分けをしてもよい。これにより、検査の時間を少なくでき、コストを抑えることができる。
【００７４】
【発明の効果】
本発明によれば、以下のような効果がある。
請求項１〜６によれば、受光素子が検出した輝度レベルに、ずれ補正手段が、被検査表示機器の画素と受光素子との写像の位置関係によって輝度レベルを補正し、さらに、輝度補正手段が、応答特性に基づき補正を行うので、１画素からの光を検出する受光素子の数が少なく、さらに応答特性の光強度が非対称でも、受光素子から輝度レベルを精度よく求めることができる。これにより、被検査表示機器の１画素に対する受光素子数が少なくとも、画素の欠陥を精度良く検査することができる。従って、高価で入手が困難なＣＣＤカメラ３０を用いる必要がなく、検査装置のコストを抑えることができる。
【００７５】
請求項２によれば、エリアごとのずれ量、および応答特性によって輝度レベルを補正するので、光路によらず輝度レベルを精度よく補正することができる。これにより、画素の欠陥をより精度よく検査することができる。
【００７６】
請求項３〜５によれば、ランク決定手段が、欠陥画素の配置によって、被検査表示機器のランク分けを行うので、ユーザの視認性にあった検査ができる。これにより、画素の欠陥が同一の数であっても、被検査表示機器の画素のランクを正確に検査することができる。
【００７７】
請求項７〜９によれば、被検査表示機器の画素と受光素子との写像の位置関係によって、受光素子からの輝度レベルを補正し、この補正した輝度レベルを、被検査表示機器の画素から受光素子までの光の応答特性によって補正するので、受光素子からの輝度レベルを精度よく補正することができる。これにより、被検査表示機器の１画素に対する受光素子数が少なくとも、画素の欠陥を精度よく検査することができる。
【００７８】
請求項８によれば、欠陥と判定された画素の配置によって、被検査表示機器のランク分けをするので、ユーザの視認性にあった検査ができる。これにより、画素の欠陥が同一の数であっても、被検査表示機器の画素のランクを正確に検査することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施例を示した構成図である。
【図２】図１に示す装置における検査部６０の動作を示したフローチャートである。
【図３】受光素子３１の一部の詳細な構成を示した図である。
【図４】本発明の第２の実施例を示した構成図である。
【図５】本発明の第３の実施例を示した構成図である。
【図６】従来の画素検査装置の構成を示した図である。
【図７】受光素子３１の一部の詳細な構成を示した図である。
【符号の説明】
１０　液晶ディスプレイ
３１　受光素子
６０　検査部
６１　ずれ量記憶手段
６２　補正係数記憶手段
６３　ずれ補正手段
６４　輝度補正手段
６５　判定手段
６６　ランク決定手段[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pixel inspection apparatus and a pixel inspection method for a display device that operates and performs display for each pixel, and more particularly, accurately inspects a pixel of a display device to be inspected for at least the number of light receiving elements for one pixel, and for a pixel defect. The present invention relates to a pixel inspection device and a pixel inspection method.
[0002]
[Prior art]
There are many display devices that operate on a pixel-by-pixel basis and display images by electrically controlling the optical characteristics of luminance, reflectance, or transmittance, including those under research and development, and have been put into practical use. There are a liquid crystal panel, a liquid crystal display, a plasma display, an organic EL (electroluminescence) display, an LED (light emitting diode) display and the like as a direct-view type or a projection type.
[0003]
Such a display device, unlike a cathode ray tube that scans and displays an electron beam, operates on a pixel-by-pixel basis to control the light output, but a pixel that cannot control the light output at the manufacturing stage, that is, a defective pixel May occur. The pixel inspection device is a device that inspects a pixel of such a display device for a defect.
[0004]
FIG. 6 is a diagram illustrating a configuration example of a conventional pixel inspection device. In FIG. 6, a liquid crystal display 10 is a display device to be inspected, in which a backlight and a liquid crystal panel are integrally formed. The liquid crystal panel has N × M (N, M: integer) pixels.
[0005]
The pixel inspection apparatus includes an inspection pattern output unit 20, a CCD (charge coupled devices) camera 30, an optical system 40, and an inspection unit 50. The inspection pattern output unit 20 causes the liquid crystal display 10 to display an image with a desired inspection pattern.
[0006]
The CCD camera 30 has a plurality of light receiving elements 31 on the same light receiving surface, and detects an image displayed on the liquid crystal display 10, that is, light output from each pixel, with each light receiving element 31. A luminance level based on the detected light is output. Further, the number of the light receiving elements 31 is provided sufficiently larger than the number of pixels of the liquid crystal panel 10, and the positional relationship of the mapping between each light receiving element 31 and the pixel is adjusted and determined before the inspection.
[0007]
The optical system 40 includes one or a plurality of lenses 41, is provided between the liquid crystal display 10 and the CCD camera 30, and allows light from the liquid crystal display 10 to efficiently enter the CCD camera 30.
[0008]
The inspection unit 50 includes a correction coefficient storage unit 51, a luminance correction unit 52, and a determination unit 53. The inspection unit 50 determines a defective pixel of the liquid crystal display 10 based on the luminance level from the CCD camera 30 and the inspection pattern of the inspection pattern output unit 20. Inspect.
[0009]
Further, the correction coefficient storage unit 51 stores a correction coefficient. The brightness correction means 52 corrects the brightness level of each light receiving element 31 based on the brightness level from each light receiving element 31 of the CCD camera 30 and the correction coefficient of the correction coefficient storage means 51. The judging means 53 judges whether a pixel of the liquid crystal display 10 has a defect based on the corrected luminance level from the luminance correcting means 52 and the test pattern of the test pattern output unit 20.
[0010]
The operation of such a device is described below. The test pattern output unit 20 displays each pixel of the liquid crystal display 10 in a desired test pattern, for example, one line at a time, or displays or hides all pixels.
[0011]
Then, each light receiving element 31 of the CCD camera 30 detects light output from each pixel of the liquid crystal display 10 via the lens 41 of the optical system 40. Further, the CCD camera 30 outputs the brightness level of the light detected by the light receiving element 31 to the brightness correction means 52 of the inspection unit 50.
[0012]
Then, the luminance correction unit 52 of the inspection unit 50 corrects the luminance level of the light receiving element 31 with the correction coefficient read from the correction coefficient storage unit 51 for each light receiving element 31.
[0013]
The correction operation of the brightness correction means 52 will be specifically described with reference to a part of the light receiving element 31 of the CCD camera 30. FIG. 7 shows a partial light receiving element a ₁₁ ~ A _Fifteen , A ₂₁ ~ A ₂₅ , A ₃₁ ~ A ₃₅ , A ₄₁ ~ A ₄₅ , A ₅₁ ~ A ₅₅ (Hereinafter a _ij It expresses. However, i and j are both integers and represent a configuration of 1 to 5) and the output of the luminance level. FIG. 7A shows a part of the light receiving element a of the CCD camera 30. _ij FIG. 7B shows a light receiving element a ₃₁ ~ A ₃₅ Represents a luminance level based on the detected light.
[0014]
In FIG. 7A, the light receiving element a _ij Are arranged in a matrix of 5 rows and 5 columns. The light-emitting pixel position L0 indicates a position where one pixel of the liquid crystal display 10 corresponds on the light receiving surface of the CCD camera 30. In FIG. 7B, the horizontal axis represents the light receiving element a. ₃₁ ~ A ₃₅ , And the vertical axis is the luminance level.
[0015]
Subsequently, when only one pixel of the liquid crystal display 10 corresponding to the light emitting pixel position L0 emits light, the light receiving element a ₃₁ ~ A ₃₅ The luminance level detected in step (1) will be described with reference to FIG. In an ideal state, the light receiving element a overlapping the light emitting pixel position L0 ₃₄ , A ₃₅ Light is detected only by the other light receiving element a ₃₁ ~ A ₃₃ Does not detect light.
[0016]
However, in practice, the light receiving element a of the CCD camera 30 is _ij In the optical path up to, there is a lens 41, a protective glass (not shown) of the CCD camera 30, a coating (not shown), and the like, so that the light spreads more on the light receiving surface than in an ideal state. This spread of light is called a response characteristic, and is represented by a point spread function (PSF).
[0017]
Therefore, as indicated by the point x, the light receiving element a overlapping the light emitting pixel position L0 ₃₄ , A ₃₅ As well as other light receiving elements a ₃₁ ~ A ₃₃ But light is detected. Incidentally, such a phenomenon is called crosstalk. Then, the light receiving element a ₃₄ , A ₃₅ The luminance level of the light receiving element a is reduced as compared with the ideal state, and no light should be detected. ₃₁ ~ A ₃₃ Also has output.
[0018]
The luminance correction unit 52 corrects the influence of such crosstalk. For example, the light receiving element a ₃₃ When correcting the brightness level of the light receiving element a, ₃₃ A light receiving element a near the center ₁₂ ~ A ₁₄ , A ₂₁ ~ A ₂₅ , A ₃₁ , A ₃₂ , A ₃₄ , A ₃₅ , A ₄₁ ~ A ₄₅ , A ₅₂ ~ A ₅₄ And the correction is performed according to equation (1).
[0019]
ap ' ₃₃ ＝ α ・ ap ₃₃ + Β ・ (ap ₂₂ + Ap ₂₃ + Ap ₂₄ + Ap ₃₂ + Ap ₃₄ + Ap ₄₂ + Ap ₄₃ + Ap ₄₄ ) + Γ · (ap ₁₂ + Ap ₁₃ + Ap ₁₄ + Ap ₂₁ + Ap ₂₅ + Ap ₃₁ + Ap ₃₅ + Ap ₄₁ + Ap ₄₅ + Ap ₅₂ + Ap ₅₃ + Ap ₅₄ (1)
[0020]
Here, the brightness level ap _ij Is the light receiving element a _ij And the luminance level ap ' ₃₃ Is the light receiving element a ₃₃ Brightness level ap ₃₃ Is a corrected value. The correction coefficients α, β, and γ are calculated based on the pixels of the liquid crystal display 10 from the light receiving element a. _ij Is a coefficient determined by the response characteristics of light.
[0021]
Such correction is performed by the luminance correction unit 52 using the correction coefficients α, β, and γ stored in the correction coefficient storage unit 51 by using the light receiving elements a of the CCD camera 30. _ij Brightness level ap _ij And the luminance level is corrected to a luminance level represented by a dot shown in FIG.
[0022]
Returning to FIG. 6 again, the judging means 53 compares the luminance level corrected by the equation (1) with the test pattern from the test pattern output unit 20, and for example, as shown in FIG. In the case of an inspection pattern in which only one pixel at the position L0 is displayed, a light receiving element overlapping with the light emitting pixel position L0 (in FIG. 7B, the light receiving element a ₃₄ , A ₃₅ ) To determine whether a desired luminance level is output, and a light receiving element that does not overlap with the light emitting pixel position L0 (in FIG. 7B, the light receiving element a ₃₁ ~ A ₃₃ ), It is determined whether a luminance level of 0 or a value close to 0 is output, and the presence or absence of a pixel defect is inspected.
[0023]
[Problems to be solved by the invention]
Such a pixel inspection device detects one pixel of the liquid crystal display 10 with a plurality of light receiving elements 31 in order to inspect the liquid crystal display 10. In general, it is desirable to perform detection by four times or more, that is, 16 or more light receiving elements 31 vertically and horizontally for one pixel.
[0024]
However, in recent years, as the resolution of the liquid crystal display 10 has been increased, the number of pixels per unit area has increased, and the number of light receiving elements 31 of the CCD camera 30 that relatively detects one pixel has decreased significantly. The ratio has decreased to 1: 2, 1: 1. Therefore, it is easily affected by the distortion of the optical system 40 and the like and the shift of the positional relationship of the mapping between the pixel and the light receiving element 31.
[0025]
That is, the brightness correction unit 52 calculates the brightness level a _ij , But assumes that the PSF is point symmetric. Therefore, the light receiving element a of interest ₃₃ From adjacent light receiving elements a having almost the same distance from ₂₂ ~ A ₂₄ , A ₃₂ , A ₃₄ , A ₄₂ ~ A ₄₄ Multiplied by the correction coefficient β assuming the same crosstalk effect, and similarly, adjacent light receiving elements a having substantially the same distance. ₁₂ ~ A ₁₄ , A ₂₁ , A ₂₅ , A ₃₁ , A ₃₅ , A ₄₁ , A ₄₅ , A ₅₂ ~ A ₅₄ Is multiplied by a correction coefficient γ. However, actually, due to the influence of distortion of the optical system 40 and the like such as coma aberration and chromatic aberration, the PSF representing the response characteristic is not point-symmetric and the elephant on the light receiving surface is distorted. Specifically, when the light intensity is represented by a contour line, the light intensity is not a square but an ellipse. Thereby, the brightness level ap _ij Cannot be accurately corrected, and the accuracy of inspection decreases.
[0026]
If the positional relationship between the pixel and the light receiving element 31 for each device to be inspected deviates from the reference positional relationship, that is, the positional relationship when the correction coefficients α, β, and γ are obtained, the light receiving element according to Expression (1) is obtained. a _ij Brightness level ap _ij There is a problem that the correction of the image is further deteriorated. Of course, in order to avoid these problems, it is possible to increase the number of the light receiving elements 31 of the CCD camera 30 and to perform inspection. is there.
[0027]
SUMMARY OF THE INVENTION An object of the present invention is to realize a pixel inspection apparatus and a pixel inspection method for accurately inspecting a pixel for defects with at least the number of light receiving elements per pixel of a display device to be inspected.
[0028]
[Means for Solving the Problems]
The invention according to claim 1 is
A desired inspection pattern is displayed on a display device to be inspected which operates and displays for each pixel, light from pixels of the display device to be inspected is detected by a plurality of light receiving elements, and defects of the pixels of the display device to be inspected are detected. In the pixel inspection device to inspect,
A shift correction unit that corrects a luminance level from a light receiving element by a positional relationship between a pixel of the display device to be inspected and the light receiving element,
A luminance correction unit that corrects the luminance level corrected by the shift correction unit based on a response characteristic of light from a pixel of the display device to be inspected to the light receiving element;
Determining means for determining a pixel defect from the luminance level corrected by the luminance correcting means and the inspection pattern;
Is provided.
[0029]
The invention according to claim 2 is the invention according to claim 1,
The shift correcting unit divides the pixel of the display device under inspection into a plurality of areas, and corrects the luminance level from the light receiving element according to the positional relationship of the mapping between the pixel and the light receiving element for each area,
The brightness correction means corrects the brightness level corrected by the shift correction means according to the light response characteristics of each area.
[0030]
The invention according to claim 3 is the invention according to claim 1 or 2,
It is characterized in that rank determining means is provided for classifying the display device under inspection according to the arrangement of the pixels of the display device under inspection determined to be defective by the determining unit.
[0031]
The invention according to claim 4 is the invention according to claim 3,
The rank determining means detects whether or not there is a pixel defect for at least two consecutive pixels, and performs rank classification.
[0032]
The invention according to claim 5 is the invention according to claim 3 or 4,
The rank deciding means is characterized in that ranks are determined for pixels in a desired area among pixels of the display device to be inspected.
[0033]
The invention according to claim 6 is the invention according to any one of claims 1 to 5,
The display device to be inspected is one of a liquid crystal panel, a liquid crystal display, a plasma display, an organic EL display, and an LED display.
[0034]
The invention according to claim 7 is
Pixel inspection for displaying a desired inspection pattern on a display device to be inspected that operates for each pixel, detecting light from the pixels of the display device to be inspected by a plurality of light receiving elements, and inspecting the defects of the pixels of the display device to be inspected In the method,
The pixel of the display device to be inspected and the positional relationship of the mapping of the light receiving element, to correct the luminance level of the light receiving element,
The corrected luminance level is corrected by a response characteristic of light from the pixel of the display device under inspection to the light receiving element,
A defect of a pixel is determined from the luminance level corrected by the response characteristic of the light and the inspection pattern.
[0035]
The invention according to claim 8 is the invention according to claim 7,
The display device to be inspected is ranked according to the arrangement of the pixels determined to be defective.
[0036]
The invention according to claim 9 is the invention according to claim 7 or 8,
The present invention is characterized by inspecting a display device to be inspected, which is one of a liquid crystal panel, a liquid crystal display, a plasma display, an organic EL display, and an LED display.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the present invention. 6 that are the same as those in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted.
[0038]
In FIG. 1, an inspection unit 60 is provided instead of the inspection unit 50. Here, the pixel inspection device includes an inspection pattern output unit 20, a CCD camera 30, an optical system 40, and an inspection unit 60. The inspection unit 60 includes a shift amount storage unit 61, a correction coefficient storage unit 62, a shift correction unit 63, a brightness correction unit 64, and a determination unit 65, and determines the brightness level from the CCD camera 30 between the pixel and the light receiving element 31. The correction is performed based on the positional relationship of the mapping and the response characteristics of light from the pixel to the light receiving element 31, and further, a defective pixel of the liquid crystal display 10 is inspected from the inspection pattern of the inspection pattern output unit 20.
[0039]
Then, the shift amount storage means 61 stores the shift amount of the positional relationship between the image of the pixel of the liquid crystal display 10 and the light receiving element 31 of the CCD camera 30. The correction coefficient storage unit 62 stores a correction coefficient based on a response characteristic of light from the pixel to the light receiving element 31. The shift correction unit 63 corrects the luminance level of each light receiving element 31 of the CCD camera 30 based on the shift amount of the shift amount storage unit 61.
[0040]
The luminance correction unit 64 corrects the luminance level corrected by the shift correction unit 63 by the correction coefficient of the correction coefficient storage unit 62 to the effect of crosstalk between the light receiving elements 31.
[0041]
The determining unit 65 determines whether a pixel of the liquid crystal display 10 has a defect based on the corrected luminance level from the luminance correcting unit 64 and the test pattern from the test pattern output unit 20.
[0042]
The operation of such a device is described below. The test pattern output unit 20 displays each pixel of the liquid crystal display 10 in a desired test pattern, for example, one line at a time, or displays or hides all pixels.
[0043]
Then, each light receiving element 31 of the CCD camera 30 detects light output from each pixel of the liquid crystal display 10 via the lens 41 of the optical system 40. Further, the CCD camera 30 outputs the luminance level of the light detected by the light receiving element 31 to the displacement correcting means 63 of the inspection unit 60.
[0044]
Next, the operation of the inspection unit 60 will be described with reference to the flowchart of FIG. The shift correcting unit 63 of the inspection unit 60 reads the shift amount from the shift amount storage unit 61 (S10). Then, the luminance level from each light receiving element 31 of the CCD camera 30 is corrected based on the read deviation amount (S11).
[0045]
The operation (S11) of the shift correcting means 63 will be specifically described with reference to a part of the light receiving element 31 of the CCD camera 30. FIG. 3 shows a partial light receiving element a ₁₁ ~ A _Fifteen , A ₂₁ ~ A ₂₅ , A ₃₁ ~ A ₃₅ , A ₄₁ ~ A ₄₅ , A ₅₁ ~ A ₅₅ (Hereinafter a _ij ). The same components as those in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.
[0046]
In FIG. 3, a light-emitting pixel position L <b> 1 indicates a position where one pixel of the liquid crystal display 10 corresponds on the light receiving surface of the CCD camera 30. The light emitting pixel position L1 is located at the light receiving element a ₃₃ And the light receiving element a ₃₃ Is approximately equal to the area of
[0047]
The shift amounts Δx and Δy are determined by the light receiving element a ₃₃ Is shifted from the center of the light emitting pixel position L1. Further, the shift amount Δx is determined by the light receiving element a ₃₁ , A ₃₅ And the amount of deviation Δy is determined by the light receiving element a ₁₃ , A ₅₃ On the axis connecting. The shift amounts Δx and Δy are based on the light receiving element a _ij Is a value normalized by the element width in each axis direction.
[0048]
The deviation amounts Δx and Δy are obtained when the device to be inspected is installed before the inspection, and are stored in the deviation amount storage unit 61. For example, only one pixel corresponding to the light emitting pixel position L1 is turned on, and the light receiving element a near the pixel is turned on. _ij The maximum value is obtained by performing Lagrange complementation on the luminance level from, and the position of this maximum value and the light receiving pixel a of interest ₃₃ Is calculated, and the shift amounts Δx and Δy of the calculation result are stored in the shift amount storage unit 61.
[0049]
Then, at the time of inspection, the shift correcting unit 63 uses the shift amounts Δx and Δy read from the shift amount storage unit 61 to detect the light receiving element a of interest. ₃₃ Brightness level ap ₃₃ Is corrected by the following equation (2).
[0050]
ac ₃₃ = (1-Δx) · (1-Δy) · ap ₃₃ + Δx ・ (1-Δy) ・ ap ₃₂ + Δx ・ Δy ・ ap ₄₂ + (1-Δx) · Δy · ap ₄₃ (2)
[0051]
Where ap ₃₂ , Ap ₄₂ , Ap ₄₃ Is the light receiving element a where the light emitting pixel position L1 overlaps ₃₂ , A ₄₂ , A ₄₃ The brightness level from each, ac ₃₃ Is the corrected light receiving element a ₃₃ Luminance level.
[0052]
As described above, the shift correcting means 63 is provided for each light receiving element a _ij Brightness level ap for each _ij Is corrected, and the luminance level ac is corrected. _ij Ask for.
[0053]
Returning to the flowchart of FIG. 2 again, the luminance correction unit 64 reads the correction coefficient from the correction coefficient storage unit 62 (S12), and the luminance level ac corrected by the deviation correction unit 63. _ij Then, the influence of the crosstalk is corrected (S13). For example, the brightness correction means 64 is a light receiving element a shown in FIG. ₃₃ Luminance level ac after deviation correction ₃₃ , The correction is performed by the following equation (3).
[0054]
(Equation 1)

[0055]
Where A ₃₃ Is the light receiving element a of interest ₃₃ Brightness level ac ₃₃ Is the brightness level after the correction. Also, Ks _ij Is the light receiving element a of interest ₃₃ 25 light receiving elements a in 5 rows and 5 columns centered on _ij Is a correction coefficient for each. Thus, the brightness level ac _ij To correct the brightness level A _ij Ask for.
[0056]
However, this correction coefficient Ks _ij Is determined by setting the display device for adjustment so that the deviation amounts Δx and Δy become 0 before performing the inspection. Specifically, the light receiving element a ₃₃ Are displayed only on the pixels corresponding to _ij Brightness level ap _ij (= Ac _ij ). That is, the light receiving element a ₃₃ Brightness level A ₃₃ Only the non-zero value and the remaining light receiving elements a ₁₁ ~ A _Fifteen , A ₂₁ ~ A ₂₅ , A ₃₁ , A ₃₂ , A ₃₄ , A ₃₅ , A ₄₁ ~ A ₄₅ , A ₅₁ ~ A ₅₅ Brightness level A ₁₁ ~ A _Fifteen , A ₂₁ ~ A ₂₅ , A ₃₁ , A ₃₂ , A ₃₄ , A ₃₅ , A ₄₁ ~ A ₄₅ , A ₅₁ ~ A ₅₅ Becomes 0. In this way, 25 simultaneous equations are created, and the correction coefficient Ks _ij Ask for. In order to obtain an average effect, more equations are simultaneously set, and the correction coefficient Ks is calculated by the least square method. _ij May be requested. Then, the obtained correction coefficient Ks _ij Is stored in the correction coefficient storage means 62.
[0057]
Then, the judging means 65 sets the luminance level A corrected by the equation (3). _ij Is compared with the inspection pattern from the inspection pattern output unit 20 to inspect whether or not the pixel has a defect (S14). For example, (a) when displaying all pixels, the corrected luminance level A _ij Is lower than the desired luminance level, the pixel corresponding to the light receiving element 31 is determined to be defective. (B) Corrected brightness level A when all pixels are not displayed _ij Is higher than the desired luminance level, the pixel corresponding to the light receiving element 31 is determined to be defective. (C) The corrected luminance level A is set by setting the luminance level of the pixel to 50% of the maximum value. _ij However, if it does not fall within the range of 50% ± q% (q: an integer) of the maximum luminance level, the pixel corresponding to the light receiving element 31 is determined to be defective.
[0058]
In the case of the conventional correction method using Equation (1), if the PSF is not point-symmetric, the distribution of bright spots and dark spots cannot be corrected with high accuracy, and the number of pixel defects must be accurately obtained. Can not. For example, the entire screen is not displayed, and one pixel has a very strong bright spot defect, and even if correction is performed according to equation (1), not only the light receiving element corresponding to that pixel but also the adjacent light receiving element A certain amount of brightness level is generated. Then, the amount may be larger than the threshold value for determining a defect. In fact, even though the defect is one pixel, it is regarded as a continuous two-pixel defect, and the number of defective pixels is detected by one more. Can not be inspected.
[0059]
However, the shift correcting means 63 detects the brightness level ap due to the shift in the positional relationship between the pixel of the liquid crystal display 10 and the light receiving element 31 of the CCD camera 30. _ij Is corrected, and the luminance correcting means 54 corrects the luminance level ac corrected by the deviation correcting means 63 with a correction coefficient based on the response characteristic. _ij Is corrected, the number of light receiving elements 31 for detecting light from one pixel is small, and even if the PSF has a two-dimensional distribution instead of point symmetry due to distortion of the optical system 40 or the like, the luminance level A _ij Can be obtained with high accuracy. Thereby, the defect of the pixel of the liquid crystal display 10 can be inspected accurately with at least the number of light receiving elements per pixel of the display device to be inspected.
[0060]
FIG. 4 is a configuration diagram showing a second embodiment of the present invention. Here, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description is omitted and the illustration is also omitted. In FIG. 4, a rank determination unit 66 is provided in the inspection unit 60. The rank determining means 66 determines the rank of the pixels of the liquid crystal display 10 based on the arrangement of the pixels determined to be defective by the determining means 65.
[0061]
The operation of such a device will be described. If the rank determining means 66 detects the arrangement of defective pixels, for example, that two or more defective pixels are continuously arranged, from the determination result of the determining means 65, the rank is determined as defective. The rank is output to an external device (not shown). Except for the operation of such rank determining means 66 for classifying the rank of the liquid crystal display based on the arrangement of defective pixels, the apparatus is the same as the apparatus shown in FIG.
[0062]
As described above, since the rank determining unit 66 determines whether or not the defective pixels are continuous, it is possible to perform the inspection according to the visibility of the user. That is, the user is more likely to recognize a defective product when defective pixels are present continuously than in discrete discontinuities. Thereby, even if the number of defective pixels is the same, the rank of the pixels of the liquid crystal display 10 can be accurately inspected.
[0063]
FIG. 5 is a configuration diagram showing a third embodiment of the present invention. Here, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description is omitted and the illustration is also omitted. 2, a screen 70 is provided between the optical system 40 and the CCD camera 30. Such an apparatus has a configuration suitable for an inspection when the liquid crystal display 10 is used in a projector of a projection type by providing a screen 70 in the inspection apparatus shown in FIG.
[0064]
The operation of the device shown in FIG. 5 will be described. The test pattern output unit 20 displays each pixel of the liquid crystal display 10 in a desired test pattern, for example, one line at a time, or displays or hides all pixels.
[0065]
Then, the optical system 40 projects the light from the liquid crystal display 10 to a desired position on the screen 70. Then, each light receiving element 31 of the CCD camera 30 detects light output from each pixel of the liquid crystal display 10 via the lens 41 of the optical system 40 and the screen 70.
[0066]
The operation other than that the optical system 40 projects light from each pixel of the liquid crystal display 10 onto the screen 70 and the CCD camera 30 detects the light projected on the screen 70 is the same as that shown in FIG. Therefore, the description is omitted. Needless to say, the CCD camera 30 may detect light reflected by the screen 70 instead of light transmitted through the screen 70.
[0067]
The present invention is not limited to this, and may be as follows.
(1) In the apparatus shown in FIGS. 1, 4 and 5, each of the shift correcting means 63 and the brightness correcting means 64 sets the brightness level from all the light receiving elements 31 to the same shift amount Δx, Δy, and the correction coefficient Ks. _ij Has been described, the shift amount Δx, Δy, and the correction coefficient Ks depend on the position of the light receiving element 31. _ij May be changed.
[0068]
For example, the light receiving element 31 is divided into nine areas, and the respective correction coefficients Ks _ij Is corrected by using the equations (2) and (3). That is, light from each pixel of the liquid crystal display 10 is detected by the CCD camera 30 via the optical system 40, the screen 70, and the like, but in the optical path passing near the center of the lens 41 and the screen 70 and the optical path passing through the peripheral portion, This is because the positional relationship between the mappings and the response characteristics of light are often different. Of course, the area of the area to be divided is not the same area, and for example, the area of the central part may be large.
[0069]
As described above, the deviation amounts Δx and Δy obtained for each area and the correction coefficient Ks _ij Since the brightness level of each light receiving element 31 is corrected in the above, the brightness level can be corrected more accurately in consideration of a variation in response characteristics caused by an optical path from a pixel. Thereby, the defect of the pixel of the liquid crystal display 10 can be inspected more accurately.
[0070]
(2) In the pixel inspection apparatus of the present invention, the display device to be inspected is the liquid crystal display 10, but the display device for electrically controlling the pixels, for example, the pixels of the liquid crystal panel, the plasma display, the organic EL display, the LED display, etc. It can be applied to inspection.
[0071]
(3) Although the example in which the light from one pixel of the liquid crystal display 10 is detected by one light receiving element 31 has been described, the light may be detected by a plurality of light receiving elements 31.
[0072]
(4) The light receiving element a focused on by the brightness correction means 64 ₃₃ 25 light receiving elements a including _ij Brightness level ap _ij The light receiving element a for performing this correction _ij May be any number. For example, a portion having a large distortion, such as the optical system 40, has more light receiving elements a _ij The light receiving element a of interest using ₃₃ Brightness level ap ₃₃ May be corrected.
[0073]
(5) In the apparatus shown in FIG. 4, the rank determining means 66 inspects the arrangement of the pixel defects of the liquid crystal display 10 for all the pixels, but the user can easily recognize the pixel defects. The inspection may be performed on only the pixels near the center of the target to be ranked. As a result, the inspection time can be reduced, and the cost can be reduced.
[0074]
【The invention's effect】
According to the present invention, the following effects can be obtained.
According to the first to sixth aspects, the shift correcting means corrects the luminance level to the luminance level detected by the light receiving element according to the positional relationship of the mapping between the pixel of the display device to be inspected and the light receiving element. However, since the correction is performed based on the response characteristics, the number of light receiving elements for detecting light from one pixel is small, and even if the light intensity of the response characteristics is asymmetric, the luminance level can be accurately obtained from the light receiving elements. Thus, the number of light receiving elements for one pixel of the display device to be inspected can be at least inspected for a defect of the pixel with high accuracy. Therefore, it is not necessary to use the expensive and difficult to obtain CCD camera 30, and the cost of the inspection apparatus can be reduced.
[0075]
According to the second aspect, since the luminance level is corrected based on the shift amount for each area and the response characteristics, the luminance level can be accurately corrected regardless of the optical path. This makes it possible to inspect the pixel for defects with higher accuracy.
[0076]
According to the third to fifth aspects, the rank determining means ranks the display devices to be inspected according to the arrangement of the defective pixels, so that an inspection suitable for the visibility of the user can be performed. Thereby, even if the number of defects of the pixel is the same, the rank of the pixel of the display device to be inspected can be accurately inspected.
[0077]
According to the seventh to ninth aspects, the luminance level from the light receiving element is corrected according to the positional relationship of the mapping between the pixel of the display device under inspection and the light receiving element, and the corrected luminance level is converted from the pixel of the display apparatus under inspection. Since the correction is made based on the response characteristic of the light to the light receiving element, the luminance level from the light receiving element can be corrected with high accuracy. Thus, the number of light receiving elements for one pixel of the display device to be inspected can be at least inspected with high accuracy for pixel defects.
[0078]
According to the eighth aspect, the display devices to be inspected are classified according to the arrangement of the pixels determined to be defective, so that an inspection suitable for the visibility of the user can be performed. Thereby, even if the number of defects of the pixel is the same, the rank of the pixel of the display device to be inspected can be accurately inspected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment of the present invention.
FIG. 2 is a flowchart showing an operation of an inspection unit 60 in the apparatus shown in FIG.
FIG. 3 is a diagram showing a detailed configuration of a part of a light receiving element 31;
FIG. 4 is a configuration diagram showing a second embodiment of the present invention.
FIG. 5 is a configuration diagram showing a third embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of a conventional pixel inspection device.
FIG. 7 is a diagram showing a detailed configuration of a part of the light receiving element 31.
[Explanation of symbols]
10 Liquid crystal display
31 Light receiving element
60 Inspection unit
61 shift amount storage means
62 Correction coefficient storage means
63 deviation correction means
64 brightness correction means
65 Judgment means
66 Rank Determination Means

Claims (9)

A desired inspection pattern is displayed on a display device to be inspected which operates and displays for each pixel, light from pixels of the display device to be inspected is detected by a plurality of light receiving elements, and defects of the pixels of the display device to be inspected are detected. In the pixel inspection device to inspect,
A shift correction unit that corrects a luminance level from a light receiving element by a positional relationship between a pixel of the display device to be inspected and the light receiving element,
A luminance correction unit that corrects the luminance level corrected by the shift correction unit based on a response characteristic of light from a pixel of the display device to be inspected to the light receiving element;
A pixel inspection apparatus comprising: a determination unit that determines a defect of a pixel based on the luminance level corrected by the luminance correction unit and the inspection pattern. The shift correcting unit divides the pixel of the display device under inspection into a plurality of areas, and corrects the luminance level from the light receiving element according to the positional relationship of the mapping between the pixel and the light receiving element for each area,
2. The pixel inspection apparatus according to claim 1, wherein the brightness correction unit corrects the brightness level corrected by the shift correction unit based on a response characteristic of light for each area. 3. The pixel inspection apparatus according to claim 1, further comprising: a rank determining unit configured to classify the display device under inspection according to an arrangement of pixels of the display device under inspection determined as a defect by the determination unit. 4. The pixel inspection apparatus according to claim 3, wherein the rank determining means detects whether or not there is a pixel defect for at least two consecutive pixels, and performs a rank classification. The pixel inspection apparatus according to claim 3, wherein the rank determination unit performs a rank division on pixels in a desired area among pixels of the display device to be inspected. The pixel inspection device according to claim 1, wherein the display device to be inspected is any one of a liquid crystal panel, a liquid crystal display, a plasma display, an organic EL display, and an LED display. Pixel inspection for displaying a desired inspection pattern on a display device to be inspected that operates for each pixel, detecting light from the pixels of the display device to be inspected by a plurality of light receiving elements, and inspecting the defects of the pixels of the display device to be inspected In the method,
The pixel of the display device to be inspected and the positional relationship of the mapping of the light receiving element, to correct the luminance level of the light receiving element,
The corrected luminance level is corrected by a response characteristic of light from the pixel of the display device under inspection to the light receiving element,
A pixel inspection method, wherein a defect of a pixel is determined from the luminance level corrected based on the light response characteristic and the inspection pattern. 8. The pixel inspection method according to claim 7, wherein the display devices to be inspected are ranked according to the arrangement of the pixels determined to be defective. 9. The pixel inspection method according to claim 7, wherein a display device to be inspected is any one of a liquid crystal panel, a liquid crystal display, a plasma display, an organic EL display, and an LED display.

Images