JPH0657071B2 - Convergence error correction method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting and correcting a convergence error in a display device such as a color picture tube.

(Prior Art) Conventionally, in order to detect a convergence error of a color display device, an adjuster is mostly visually performed, and thus the convergence correction is very time-consuming.

Further, as an electronic method, for example, Japanese Patent Publication No. 58-3
As described in Japanese Patent No. 8995, "Convergence Color Shift Detection Method and Its Device", R (red), G (green), and B (blue) grid patterns are sequentially arranged at the same position on the screen of the color picture tube to be inspected. By projecting and adjusting the position of the image pickup device arranged in front of the screen, a video signal exhibiting one mountain-shaped waveform is extracted from the grid pattern of each color projected on the screen, and each of the video signals is extracted. Measuring the peak position of the waveform with reference to the horizontal synchronizing signal of the image pickup device,
This is detected as the color shift of the convergence of the color picture tube and is used to correct the convergence error.

(Problems to be Solved by the Invention) In the conventional example in which the color convergence error adjustment is visually performed, it takes time as the screen becomes larger, and the human eye makes a judgment, so that the error correction cannot be promptly performed in the optimum state. Have difficulty.

Convergence error must be detected with an accuracy of one scanning line or less. However, in the detection method described in Japanese Patent Publication No. 58-38995, since a pulse having a narrow mountain waveform is used for the detection signal, the detection camera (imaging Considering the resolution of the device, one camera (imaging device) enlarges a part of the screen for viewing. Therefore, when trying to detect the convergence error for the entire screen, the camera is moved to detect one point at a time, or multiple cameras are used and each camera takes charge of only a part of the screen. There is a drawback that it is not practical in terms of time or cost.

(Means for Solving Problems) Therefore, the object of the method of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide color convergence at each point of the entire display screen of the display device at one time with only one imaging camera for detection. It is intended to provide a practical method capable of accurately detecting an error and correcting the error.

That is, in the convergence error correction method of the present invention, when adjusting the convergence of the color image display device, the entire display screen of the color image display device is divided into positive integers N and M in the horizontal and vertical directions, respectively, and the matrix is formed. The display signal waveform of each color in each region is a bilateral symmetrical waveform signal in which the waveform is a mountain-shaped waveform when viewed in the horizontal and vertical directions of the screen, and the signal generator supplies the image display device with the color image display device. A signal from an image pickup device that picks up a display screen of the device is guided to an image processing device, and a horizontal and vertical center of gravity error value of the screen is calculated for each area, and the color image display device of the color image display device is calculated based on the calculated center of gravity error value. The feature is that the convergence is adjusted.

(Operation) Conventionally, a high-frequency video signal is used as a video pattern for measuring the color convergence error, so that it is easily affected by jitter or noise, and if only one imaging camera is used for detection, the accuracy is improved. Although it is necessary to enlarge only a part of the screen, since the method of the present invention uses a low-frequency signal as an error detection pattern, the convergence error is obtained from the integration of a large area of the screen, and the accuracy is increased. Since it is a signal, the entire screen can be viewed with one imaging camera.

(Example) The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the configuration of a display device convergence error detection and correction device according to the present invention. The device shown here is a display device 1 for measuring convergence error, a signal generator 2 for sending a display signal to the display device 1, and a display signal for the display device 1.
The signal switch 3 that outputs only one of (red), G (green), and B (blue), the imaging device 4 for imaging the signal displayed on the display device 1, and the imaging device 4 It is composed of an image processing device 5 for processing a signal to detect a convergence error and a controller 6 for controlling the image processing device 5.

The signal generator 2 produces a low-frequency signal, which is represented by the following equation (1) that forms a repeating pattern on the horizontal x-axis of the screen and the vertical y-axis of the screen as shown in FIG. ), (2), and (3) are generated.

In the range of x other than the above, f (x) = 0 (1) In the range of y other than the above, g (y) = 0 (2) h (x, y) = f (x) · g (y) (3) where N and M may be positive integers around 10. Each x
This corresponds to the number of signal peaks in the axial and y-axis directions. A pattern is displayed on the display device 1 by this generated signal, but at that time, only one of R, G, and B colors is switched by the signal switching device 3.

The image pickup device 4 picks up an image of the entire screen of the display device 1 with, for example, a monochrome camera, and the video output thereof is sent to the image processing device 5.

The image processing device 5 has, for example, the configuration shown in FIG.
The video signal from the image pickup device 4 is first guided to the sync separation circuit 8. In addition, it is converted into a digital signal by the A / D converter 7 and sent to the image memory 9. At this time, the memory controller 10 is controlled by the synchronization signal generated by the synchronization separation circuit 8.
Is operated and the video signal is stored in the image memory 9 so that it can be easily processed by the computer 11. The signal processing is performed in the computer 11 after the whole one screen is stored. To reduce the influence of noise, an adder 12 shown by a dotted line in FIG. 3 is added to the input side of the image memory 9, It is also possible to add signals for several screens.

Next, the processing in the computer 11 will be considered. The same process is applied to the image of any area of the screen which is divided into N in the horizontal direction and M in the vertical direction. Therefore, as shown in FIGS.
Only one of the illustrated mountain shapes will be described.

The displayed signals of the respective channels R, G, B have the center positions displaced by Δx, Δy (the displacement in the horizontal and vertical directions, respectively) due to the deflection distortion of the display device, and are represented by the formulas (4) to (6).

In the range of x other than the above, f ₁ (x) = 0 (4) In the range of y other than the above, g ₁ (y) 0 (5) h ₁ (x, y) = f ₁ (x) · g ₁ (y) (6) Here, the gamma of the display device is considered for simplification. No, but in principle there is no problem. This signal is picked up by the image pickup device 4 and input to the image memory 9 in the image processing device 5. The question is whether Δx and Δy can be calculated at this time.

Using equations (7) and (8) as one method, Δx and Δy can be calculated.

Specifically, the signals in the image memory 9 are discontinuous values. That equation (4), (5), is shown in FIG. 5 a material obtained by further N ₁ M ₁ divides one region 2x ₁ × 2y ₁ full screen NM division used in (6), N _1, M ₁ If both are selected to be about 50, the signal h ₁ n ₁ m ₁ in that small area is It becomes a signal corresponding to 1 pixel represented by, and A / D in Fig. 3
Considering the use of the converter 7, h ₁ n ₁ m ₁ is a quantized value of about 8 bits.

Therefore, Δx and Δy in the above equations (7) and (8) are calculated by the following equations (10) and (1
It can be approximated by 1).

As a result of actually executing the computer simulation based on the equations (10) and (11), even if the number of divisions N ₁ or M ₁ is about 10,
It was found that an error of about 1/10 of one scanning line of 1 can be detected. Therefore, it is not necessary to use a special camera having a special resolution as the image pickup device 4.

As the next procedure, Δx and Δy in equations (10) and (11) are converted into three colors R
Obtained for each signal of (red), G (green), and B (blue).
The convergence error is obtained by the difference between Δx and Δy of each channel. Further, in the above procedure, each peak of the signals shown in the second diagram, that is, in the formulas (1) and (2), n = 0, 1, ..., N
Convergence error of the entire screen is detected by performing only -1 and m = 0, 1, 2, ..., M-1 times.

If the input image has a set-up, h ₁ (x, y) ＝ f ₁ (x) ・ g ₁ (y) + A (12) Then the true convergence error is Detected as.

In the above embodiment, the operations such as the expressions (7) and (8) are used, but as other operations, the operations such as the expressions (19) to (22) are used.
There is also a calculation using the following formula.

And Becomes

Further, although the black and white camera has been used as the image pickup device 4 in the above embodiments, the method of bringing the photo sensor into close contact with the display device, R, G, B without using the signal switch 3 shown in FIG.
A method of displaying all the colors on a display device at the same time and capturing an image with a color camera, a method of using a monochrome camera and a color filter in the above method, and the like can be considered.

Furthermore, instead of capturing the entire screen, as shown in FIG. 6, the photo sensor 14 is brought into close contact with the screen surface 13 of the display device at only a few points to a few tens points, and the phase of the generator is sequentially changed. The output of the photo sensor is equivalent to the above camera output. When the photo sensor is used, the image processing device 5 is as shown in FIG.

Although the equations (1) and (2) are used as the signals in the above embodiments, the signals are not limited to these as long as they are low frequency signals, and signals such as equations (23) and (24) may be used.

In the range of x other than the above, f ₂ (x) = 0g ₂ (y) is isomorphic to f ₂ (x) (23) In the range of x other than the above, f ₃ (x) = 0 g ₃ (y) has the same shape as f ₃ (x). (24) When the method of the present invention is further extended, the signal generated by the signal generator 2 is replaced by a general signal. Image signal may be used. The configuration of the error detection and correction device at this time is as shown in FIG. The input general image signal and the signal picked up by the image pickup device 4 respectively pass through the low-pass filter 16, and are then obtained from the input signal (Δx, Δy) and obtained from the camera signal (Δ
The convergence error can be detected by comparing (x, Δy). At this time, if the input image signal is not suitable for detecting the convergence error, it is sufficient to wait until an appropriate signal arrives. By using such a method, the convergence error can be detected without using the signal generator 2.

The method of the present invention can also be applied to convergence error detection correction of an imaging camera. Special pattern (R,
When using a pattern that gives h (x, y) for both G and B,
In the configuration shown in FIG. 1, a special pattern is placed instead of the display device 1, and the imaging camera for measurement comes to the position of the imaging device 4.
The convergence error detected in this way is sent to the imaging camera for measurement and the convergence is corrected.

As described above, according to the method of the present invention, since a low-frequency signal is used as a convergence error detection image pattern, the detected error is the integration of error values in a large area of the screen. Therefore, the influence of noise and jitter is reduced, the accuracy is improved, and since the low frequency method is used, the error can be detected at one time at each point of the entire screen with one imaging camera, and the accuracy of the overall error correction is also high. Speed is also improved.

In addition, since the above method can be developed and a general image can be detected by selecting a pattern suitable for error detection from the image,
It is always possible to automatically perform convergence adjustment while displaying a normal image.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a convergence error correction device according to the method of the present invention, and FIG. 2 is a horizontal direction (a) and a vertical direction (a) of an error detection signal generated by the signal generator shown in FIG. FIG. 3 is a diagram showing an example of the waveform of b), FIG. 3 is a diagram showing a more detailed configuration of the first illustrated image processing apparatus, and FIGS. 4 (a) and 4 (b) are part of the second illustrated signal waveform. diagram for explaining the determination of the convergence error from Yamagata waveform, Fig. 5, one of the NM divided areas of the screen in the present invention further N ₁
FIG. 6, FIG. 7 and FIG. 7 showing division into M ₁ sections explain another embodiment of the method of the present invention in which a plurality of photosensors are discretely brought into close contact with the screen of the display device to measure the convergence error. And FIG. 8 are diagrams showing the configuration of the image processing device at that time, and FIG. 8 is a diagram showing the configuration of the error correction device when the method of the present invention is further developed. DESCRIPTION OF SYMBOLS 1 ... Display device for measurement, 2 ... Signal generator 3 ... Signal switching device, 4 ... Imaging device 5 ... Image processing device, 6 ... Controller 7 ... A / D converter, 8 ... Sync separation circuit 9 ... Image memory 10 ... Memory controller 11 ... Calculator, 12 ... Adder 13 ... Screen surface of display device 14 ... Photo sensor, 15 ... Switching device 16 ... Low-pass filter

Claims (1)

[Claims] 1. When adjusting the convergence of a color image display device, an area in which the whole display screen of the color image display device is divided into positive integers N and M in the horizontal and vertical directions, respectively, is created, and in each of the matrix-like areas. The display signal waveform of each color is supplied to the image display device from the signal generating device as one symmetric waveform signal in which the waveform is a mountain waveform when viewed in the horizontal and vertical directions of the screen, and the display screen of the color image display device is supplied. A signal from an image pickup device that picks up the image is guided to an image processing device, the horizontal and vertical center of gravity error values of the screen are calculated for each area, and the convergence of the color image display device is adjusted based on the center of gravity error value. A convergence error correction method characterized by the above.