JPH02272491A - Display screen checking device - Google Patents

Abstract

PURPOSE:To make the checking reference constant and to improve the reproducibility of a check by evaluating the gross luminance unevenness of a display screen by means of a first evaluating means, evaluating the luminance dispersion of each picture element by means of a second evaluating means, and deciding a quality based on evaluation results. CONSTITUTION:The mach filtering picture data of a low frequency picture memory 14 are read by a measuring circuit 17, and a luminance difference, a size and contour strength are measured. The mach filtering picture data of a high frequency picture memory 15 are read by a measuring circuit 21, the luminance at every picture element is measured, and supplied to an evaluating circuit 22. The evaluating circuit 22 compares the luminance of each picture element with a threshold set beforehand, and the evaluation result of the luminance dispersion of each picture element of a picture is supplied to a deciding circuit 19. The deciding circuit 19 decides whether the quality of a display screen 10 is nondefective or defective based on the evaluation result of the gross luminance unevenness of the screen and the evaluation result of the luminance dispersion of each picture element, and a decision result is printed from an output circuit 23 or outputted by a display device, etc.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a display screen inspection device that inspects brightness unevenness and variation in a display screen, and aims to improve inspection reproducibility with constant inspection standards and automate the inspection. a frequency selecting means for frequency selecting each of a low frequency component and a high frequency component of an image signal obtained by capturing an image of a display screen; and a Mach filtering means for performing Mach filtering on each of the low frequency component and high frequency component to obtain respective Mach filtered image data. a filtering means; a first evaluation means for evaluating the global brightness unevenness of the display screen by determining the brightness difference, area, and contour strength of a portion where the brightness is different from the whole from the Mach-filtered image data of the low frequency component; a second evaluation means for determining the brightness of each pixel of the display screen from the Mach-filtered image data of the high frequency component and evaluating variations in the brightness for each pixel; and evaluation results of the first and second evaluation means. and determining means for determining the quality of the display screen.

[Industrial application field]

The present invention relates to a display screen inspection device, and more particularly to a display screen inspection device for inspecting brightness unevenness and variations in a display screen.

As shown in Fig. 6 (A), some display screens have global brightness unevenness over the entire screen, as indicated by the - dotted chain line ■
The luminance (brightness) along the line is expressed as shown in (B) of the same figure. Furthermore, when enlarging part 2 in (A) of the same figure, there are variations in brightness for each pixel as shown in (C) of the same figure.
- Dotted chain line 11a.

The brightness along each mb is expressed as shown in (D) and (E) of the same figure.

When such brightness unevenness and variation in the display screen becomes large, the image quality deteriorates, so it is necessary to inspect this and improve the quality of the display screen of the display H.

[Conventional technology]

Conventionally, an inspector visually inspects a display screen for brightness unevenness and variation.

[Problem to be solved by the invention]

In conventional visual inspection, there is a problem that the inspection standards vary depending on the inspection name, and even for the same inspector, the inspection standards vary depending on the inspection situation, and the reproducibility of the inspection is poor.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a display screen inspection device that has a constant inspection standard, improves the reproducibility of inspection, and can automate the inspection.

[Means to solve the problem]

FIG. 1 shows a principle diagram of the 5A arrangement of the present invention.

In the figure, the frequency selection means selects the frequencies of each of the low frequency component and the high frequency component of the image signal representing the image of the display screen from the dance I& device 6.

Mach filtering means 2 performs Mach filtering on each of the low frequency component and the high frequency component to obtain respective Mach filtered image data.

The first evaluation means 3 calculates the brightness difference between the parts where the brightness is different from the whole, based on the Mach filtering image data of the low frequency component.
The overall brightness unevenness of the display screen is evaluated by determining the area and contour strength.

The second evaluation means 4 determines the brightness of each pixel of the display screen from the Mach filtered image data of the high frequency component, and evaluates the variation in brightness of each pixel.

The determining means 5 determines the quality of the display screen based on the evaluation results of the first and second evaluating means 3 and 4.

[Effect]

In the present invention, the first evaluation means 3 evaluates the global brightness unevenness of the display screen, the second evaluation means 4 evaluates the brightness variation of each pixel, and the quality is determined based on these evaluation results. Therefore, it is possible to inspect brightness unevenness and variation similar to human visual inspection, and the inspection standard is constant and automation is possible. Further, by performing Mach filtering, the SN ratio during evaluation is improved, and accurate inspection can be performed.

〔Example〕

FIG. 2 shows a block diagram of an embodiment of the device of the present invention.

In the figure, a display 10 to be inspected displays images using a video signal at a constant brightness level. The display screen of the display 10 is developed by a silver imager 11, and the obtained image signals are supplied to a low frequency transmission circuit 12 and a high frequency transmission circuit 13, respectively.

The low frequency transmission circuit 12 transmits the low frequency components of the image signal (see Fig. 3).
The high frequency transmission circuit 13 selects the frequency of the high frequency component of the image signal (the waveform shown in FIG. 4A) and digitizes it into the low frequency image memory 14. Write to the high frequency image memory 15.

The Mach filtering circuit 16 is connected to the low frequency image memory 1
The digital image data of the waveform shown in FIG. 3 (A) is read out from 4, and the weighting of the Matsuha filter shown in FIG.
Obtain Mach filtering image data as shown in Figure 3 and fill in the old low frequency image file (S14).In Figure 3, only one dimension in the X direction is shown, but in reality Mach filtering data in two dimensions in the X and Y directions is shown. - Filtering is being performed.

The weighting width 9.1 of the Matsuha filter in FIG. 3(B) above is 10 (
It is said to be around 8.

Further, the Mach filtering circuit 16 reads digital image data having a waveform as shown in FIG. Mach-filtered image data as shown in FIG. 6(C) with highlighted portions is obtained and written into the high-frequency image memory 15 again. In this case also 2
Performs dimensional Mach filtering. Width I for weighting the Matsuha filter in Figure 4 (8) above
12 is approximately the same as the pixel interval of the display screen 10.

The Mach filtering image data in the low frequency image memory 14 is successively outputted by the measurement circuit 17, and the brightness difference d and the size S1 contour strength e l * '32 are shown in FIG. 3(C).
Each is measured. This brightness difference d.

The measurement data of size (area) S1 contour strength eI, 62 is supplied to the evaluation circuit 18. The evaluation circuit 18 sets the threshold value d, for each measurement data d, S, e+, 82, respectively.
S, e, e 2TH are preset THT
H1TH and d<drH-Ala>S<S Tll...(1b)e
+ <811H-(IC) e 2 < 82 TI ---(16)(
Evaluate whether each of 1a) to (1d) is satisfied. As shown in FIG. 5, if the size S is smaller than the threshold value 5111, it is evaluated as good; if it is larger, it is evaluated as bad; if the brightness difference d is smaller than the threshold value dr++, it is evaluated as bad; if the size S is smaller than the threshold value dr++, it is evaluated as bad; Direct elrH= e2T1
If it is smaller than 1, it is evaluated as good, and if it is larger, it is evaluated as bad.

Note that the evaluation circuit 18 obtains the evaluation function A1 or A2 expressed by the following formula, A+ = ao - d-8 (e+, ez) - (
2) A2 = a+ d-1-82*S+aff <6
+ , ez )...a (however, ao + a+ , a2.a3 are each predetermined coefficients) Evaluation function AI or A2 is set to a predetermined threshold △1■(1
Alternatively, the evaluation may be performed by comparing with A2T11.

The evaluation result of the global luminance unevenness of the screen obtained in this way is supplied to the determination circuit 19.

Further, the Mach filtering image data in the high frequency image memory 15 is continuously outputted by the measurement circuit 21, and the luminance i (x) of each pixel is measured and supplied to the evaluation circuit 22. The evaluation circuit 22 presets the brightness i (x) of each pixel as r11+a i,...1゜i (i
<i), Tll2 1i11
Ding 1121 < I (X)
<! Tll2-(4)1ll It is evaluated whether formula (4) is satisfied, and the evaluation result of the variation in brightness of each pixel on the screen is supplied to the determination circuit 19.

The determination circuit 19 determines whether the quality of the display screen 10 is good or defective based on the evaluation results of the global brightness unevenness of the screen and the evaluation results of the brightness variations in each prefecture, and outputs the determination results from the output circuit 23. Output on a printout or display.

In this way, by performing Mach filtering, the SN ratio during evaluation is improved, and accurate inspection can be performed.

Further, the measurement circuit 17 and the evaluation circuit 18 evaluate global brightness unevenness of the display screen, and the measurement circuit 21 and the evaluation circuit 22
Since the variation in brightness of each pixel is evaluated using a 3D image sensor, and the quality is judged based on these evaluation results, it is possible to inspect brightness unevenness and variation in the same way as human visual inspection, and the inspection standard is constant, improving reproducibility. , and automation is possible.

〔Effect of the invention〕

As described above, according to the display screen inspection device of the present invention, the inspection standard is constant, the reproducibility of the inspection is improved, the inspection can be automated, and it is extremely useful in practice.

This is a diagram.

In the figure, 1 is a frequency selection means; 2 is Mach filtering means; 3 is the first evaluation means, 4 is the second evaluation means, 5 is a determination means; 6.11 is an imaging mushroom shows.

Claims (1)

[Claims] Frequency selection means (
1); Mach filtering means (2) for performing Mach filtering on each of the low frequency component and the high frequency component to obtain respective Mach filtered image data; a first evaluation means (3) for evaluating the global brightness unevenness of the display screen by determining the brightness difference, area, and contour strength of the parts different from the whole; and a second evaluation means (4) that calculates the brightness of each pixel and evaluates the variation in brightness for each pixel, and evaluates the quality of the display screen based on the evaluation results of the first and second evaluation means (3, 4). A display screen inspection device characterized in that it has a determining means (5) for determining.