JPS586426B2 - Television screen automatic measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is used in the adjustment process or inspection process during the manufacturing of television receivers to determine the center position, inclination, horizontal and vertical linearity, amplitude, and scale of the image on the television screen. The present invention provides a device that can automatically measure tone, contrast, brightness, etc.

When manufacturing a television receiver, it is necessary to determine whether or not the image on the screen is normal during the adjustment and inspection processes.

However, conventionally, the measurement of the screen of a television receiver in such cases has generally been based on visual measurement by the human eye, and more specifically, measurement using calipers, illumination meters, etc. according to individual measurement items. Measurements were carried out using instruments or photographs.

In other words, when visual inspection is performed, for example, a test pattern is displayed on a television screen and Iruma looks at it to judge the deviation from the screen center, tilt, distortion, size, contrast, gradation, etc. of the image. Ta.

However, this method has the disadvantage that it lacks objectivity and has large variations depending on the measurer.

Another drawback was that in order to improve the quality of the images, it was necessary to train experienced measurers.

On the other hand, when applying various measuring instruments depending on individual measurement items, for example, the center position, inclination, distortion, and size of the image can be measured directly on the screen or after taking a photograph, using calipers, etc. Brightness, contrast, and gradation are measured directly on the screen using an illumination meter, optical power meter, or the like.

However, even in this case, although objective and absolute measurement is possible, the use of various measuring instruments requires a lot of effort and time, and online measurement is almost impossible.

Therefore, the present invention eliminates the shortcomings of these conventional measurement methods and measures the basic performance of a television screen, such as the center position, tilt, horizontal and vertical linearity, amplitude, gradation, contrast, and brightness of the image online. The object of the present invention is to provide a device that can automatically and accurately measure.

Below, an automatic television screen measuring device according to an embodiment of the present invention will be explained with reference to the drawings. First, FIG.
The configuration of an apparatus according to an embodiment of the present invention is shown, where 1 is a television receiver to be measured, 2 is its screen, and 3 is its screen frame.

The screen frame 3 is composed of an escutcheon panel and the like.

The image displayed on the screen 2 is converted into an electrical signal by the line scan camera 4, and based on this electrical signal, the arithmetic processing unit 5 performs signal processing to determine the center position, which is the basis of the image on the television screen. Automatically measures tilt, horizontal and vertical linearity, amplitude, gradation, contrast and brightness.

For these measurement items, suitable video patterns are required, so pattern video signals of high frequency or video frequency are automatically generated one after another or by instructions from the arithmetic processing unit 5 to transmit the television. A signal generator 6 for supplying to the receiver 1 is provided.

Next, the detailed configuration of this device and specific measurement operations for each measurement item will be sequentially explained.

First, to measure the center position and tilt of the image on the television screen, the screen background is set to a white level brightness as shown in Figure 3 as a pattern of the projected image, and the horizontal and vertical signals are scanned at the center. A cross-shaped orthogonal line or a rectangular line including several black lines 7a and 7b is used.

In addition, the line scan camera 4 used includes three or more image sensors in which photodiodes are arranged in a row to generate electrical signals corresponding to optical signals in a scanning manner. As shown in the figure, four image sensors 8a to 8d are arranged in # order.

Here, it is assumed that the sensors 8a and 8b and the sensors 8c and 8d are arranged accurately in parallel and perpendicularly.

Of course, another angle may be used, but in that case, it is necessary to slightly change the arithmetic processing program described below.

The state in which the television screen is projected onto the #digital image sensors 8a to 8d is approximately at the center of the image sensors 8a to 8d, as shown in FIG. The surface 2 is positioned and projected so that the screen frame 3 is also included.

The output signals from each of the image sensors 8a to 8d at this time are shown in FIG. 5A.

When this is binarized at an appropriate threshold level V, the result is D in the same figure.
A shadow electric signal caused by the crosshairs 7a and 7b appears conspicuously as shown in FIG.

That is, as shown in FIG.
Positions A1-A4, J-B,, C, ~C4, and D1- where ~8d intersects with crosshairs 7a, 7b, and screen frame 3
D4 can be clearly and accurately detected, and the distance between each detection point At A4 , BI B4 ,
CI C4, DI D4, and the distance AI (
A2, center of A3), B, -(center of B2, B3), C1 (center of C2, Cs), D,
By calculating and obtaining time widths T1 to T4 and τ1 to τ4 of the electrical signals D from each image sensor corresponding to (centers of D2 and D3) using an arithmetic processing device, the crosshairs 7a, The center and inclination of 7b can be detected.

Performing arithmetic processing from this electrical signal and performing the above detection can be realized by using conventionally used arithmetic devices for NC (numerical control) methods, analog computers, etc. The invention of specific processing will be omitted.

In addition, when the purpose is to perform online automated measurement of television receivers, the measurement conditions change because the television receiver itself on the conveyor is tilted or the screen size is different, so the center of the image on the screen It is more practical to express the position by a relative amount with respect to the screen frame rather than an absolute amount with respect to the direction in which the camera is installed.

That is, as described above, it is effective to project the image onto the image sensors 8a to 8d so as to detect the screen frame 3 around the screen 2, and measure the relative amount and inclination of the center position with respect to the screen size using this as a reference. be.

Next, measurement of horizontal and vertical linearity and amplitude of screen images will be explained.

It is of course possible to measure linearity and amplitude using separate specific pattern images, but
This can also be done using the same pattern image.

When switching, it is possible that there will be loss time due to the time required for image stabilization when switching pattern images and the storage time of the image sensor, so in the case of online measurement, linearity and amplitude fluctuations using the same pattern image may occur. Simultaneous measurement is desirable.

Here, a case where this simultaneous measurement is performed will be explained.

Furthermore, since it is clear that a completely equivalent measurement method is sufficient for both horizontal and vertical measurements, the following explanation will only cover the horizontal case. In the measurement, an image of a black and white vertical pattern as shown in FIG. 6 is used as a pattern image.

In order to display this image, a pair of equally spaced black and white image signals with a modulation factor of 100% are inserted between the synchronization signal H and the planking signal Br, as shown in FIG. 7A.

A pair of black and white is used as one pair, and the total number can be two or more, for example, P, and the widths of the white and black do not necessarily have to be the same.

The image on screen 2 of the television receiver that receives this video signal is
6, and FIG. 7B shows the output electric signal when the image of this screen 2 is photographed by the line scan camera 4.

Linearity can be measured by measuring the variation in the interval between black and white repetitions, so let the interval between the points where the image changes from white to black be l,, l2, ..., lp, and The interval between points that change from black to white is ml, m2,・
..., mp, the linearity Δl and Δm are expressed as follows.

However, here, Ai and mi are the measured values of the black and white interval in an arbitrary part, and 1,5 is the average value thereof.

As for linearity, either Δl or Δm in equation (1) may be looked at, or the average value of both may be looked at.

This measurement process 6 can be used.

Next, the amplitude originally represents how large the portion of the video signal that corresponds to the rask (the portion excluding the synchronization signal H and planking signal Br) is compared to the television screen 2. It is expressed by the following equation, where H is the converted length and H is the actual length of the screen image.

Ho/H or (Ho-H)/H (2) However, since the planking signal Br part does not appear on the screen, even if the image on screen 2 is measured with the line scan camera 4, the rusk on the image signal will not appear. The length Ho cannot be measured.

Therefore, as one approximation means, it is possible to take the width between the images at the end portions displayed on the screen 2 as equivalent to Ho.

That is, using the length HX from the first point of change from white to black in the horizontal scanning direction to the last point of change from black to white in the image of the television screen 2, HX/H or (H-
HX)/H (3) can be used as the amplitude error.

Equation (3) is actually an image sensor 8 as shown in Figure IB.
It can be determined from the output signals of a to 8d, and can be expressed as follows.

hX/h or (h-hX)/h (4) Here, the size H of the screen 2, that is, h, is known from the size of the screen frame 3 of the television receiver, so a numerical value is introduced in advance and measured. It is also possible.

In that case, there is no need to measure the size of the screen 2, so there is no need for the image at the edge of the screen to be white as shown in FIG.

Next, measurement of gradation will be explained.

For the gradation average, display the standard gradation pattern image on screen 2,
A method for measuring the brightness of each gradation and determining the number of gradations from the results, and a method for determining the number of gradations by looking at the gradation pattern of the screen to be measured and determining the point in the video signal that goes up one step from black to white. There is another method of measuring the number of gradations by determining the number of steps, and here we will discuss the latter method.

The image for measuring the gradation pattern is as shown in FIG.
, 2b, and the inside of this is divided into equal parts to create a gradation pattern image, and the number of stages is N, and the total is (N+2).
Divide into sections.

Inside the white portions 2a and 2b at both ends of the screen are black portions 2c and 2d with the lowest luminance, and further inside the black portions are a gradation pattern image 2e that sequentially changes from black to white or from white to black.

When an image of this screen 2 is photographed by a line scan camera 4, an electrical signal shown in FIG. 9A is obtained as an output signal.

As can be seen from this, there is a strong contrast between white and black at both ends of the output signal A, so if the length is K with this boundary as a reference, the length K0 of the gradation pattern image can be expressed by the following equation.

Therefore, the length R for one gradation becomes, and from this, the position of the image at each gradation level can be known.

Therefore, the brightness R1 to RN for each gradation can be measured, and the value obtained by dividing the difference between the highest brightness RN of white and the lowest brightness R1 of black by an arbitrary value If it is a gradation, it is possible to judge the gradation based on the price.

This arithmetic processing can also be performed by the arithmetic processing device 5.

Finally, the measurement of contrast and brightness will be explained.

Contrast and brightness can be measured using specific pattern images, but they can also be measured simultaneously during each of the above measurements.
That is more efficient.

That is, in each of the above measurements, the white level of the highest luminance and the black level of the lowest luminance are measured, the luminance is determined by white, and the contrast is calculated by calculating the ratio of the two.

In this case, in order to reduce errors, it is better to sample several locations in the white and black areas and average them.

In the above embodiments, the case where all the characteristics are measured has been described, but it goes without saying that one or more characteristics may be selected and measured as necessary.

Furthermore, the video to be used may be determined as appropriate depending on the purpose.

As described above, in each measurement process, the required image is projected on the screen, photographed together with the screen frame by an image sensor with photodiodes arranged in a row, and the output signal is processed by the arithmetic processing unit. By measuring the characteristics necessary for the screen of a television receiver, such as the center position, tilt, horizontal and vertical linearity, amplitude, gradation, contrast, and brightness of the image, it is possible to easily and automatically determine the characteristics in a short time. This makes it possible to obtain an optimal device for use in cases such as online measurement in the manufacturing process of television receivers.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an automatic television screen measuring device according to an embodiment of the present invention, Fig. 2 is a front view of an image sensor used in the device, and Fig. 3 is a front view of an image sensor used for measuring the center position and tilt. FIG. 4 is a front view of the screen showing an example image projected onto the image sensor; FIGS. 5A, B, C, and D are waveform diagrams showing waveforms during the same measurement; Figure 6 is a front view of a screen displaying an example of an image used to measure horizontal and vertical linearity and amplitude, Figures 7A and B are waveform diagrams showing waveforms during the same measurement, and Figure 8 9 is a front view of a screen displaying an example of an image used for measuring gradation, and FIGS. 9A and 9B are waveform diagrams showing waveforms during the same measurement. 1...Television receiver, 2...Screen, 3...Screen frame, 4...Line scan camera, 5...Calculation Processing device, 6...
...Signal generator, 8a to 8d... Image sensor.

Claims (1)

[Claims] 1 A television receiver to be measured by arranging three or more image sensors in which photodiodes are arranged in a row to generate electrical signals corresponding to optical signals in a scanning manner so as to cross each other at a predetermined angle. A line scan camera that projects the screen of the image including the screen frame onto the image sensor, and a cross-shaped or rectangular image, a vertical image, and a horizontal image on the screen of the television receiver. , a signal generator that supplies a video signal to the television receiver so as to display at least one image having a brightness gradation, and the television reception obtained from the image sensor of the line scan camera. and an arithmetic processing device for arithmetic processing of a signal corresponding to the screen image of the television receiver, and obtains an electric signal corresponding to the image from the image sensor so as to include the screen frame of the television receiver, and processes this electric signal. An automatic television screen characterized by measuring the center position, tilt, horizontal and vertical linearity, amplitude, gradation, contrast, and brightness of the image from the time interval between level change points in the middle and the electric signal level. Measuring device.