JPS5851682A - Beam alignment correcting method for television camera - Google Patents

Abstract

PURPOSE:To improve the detection accuracy, by including a center position correcting control in a beam alignment correcting control procedure and controlling the correction while preventing shift to a reference signal. CONSTITUTION:In an automatic beam alignment correction with a microprocessor 20, the center position shift of a red channel to a green (or blue) channel, is detected at a center position shift detecting circuit 19 and the microprocessor 20 discriminates whether or not the center position is shifted to a degree out of the detecting range. If the position is shifted, the center position is matched to a reference signal via a control circuit 21. Next, the alignment shift detection to the red channel is done to correct the alignment of red channel. Further, the center position matching control and the alignment correcton are repeated and the correction is done until the mis-alignment reaches a set value or below.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a beam alignment correction method for aligning the optical axis and the beam axis of an image pickup tube in a color television camera.

FIG. 1 shows a focus current supply circuit for a conventional three-tube camera. Here, 2, 4.6 are image pickup tubes for red, green, and blue colors, respectively, and 1, 3.5 are coil assemblies for red, green, and blue colors, respectively. 7 is a constant current source that generates a focus current to be supplied to the focusing coil of the coil assembly; 8 is a constant current source;

This is a focus current control circuit.

The focus current generated by this constant current source 7 is:

It is fed to the focusing coils of the series-connected coil assemblies 1, 3.5 for red, green and blue.

In the conventional manual beam alignment adjustment method, an adjustment test pattern (registration chart, etc.) is imaged in accordance with the deflection area, and a pulse indicated by 9 is applied to the constant current source 7. As a result, the focus current fluctuates in positive and negative directions at regular intervals. It is known that when the focus current changes, the 9 images shift by two rotations.

By adding this pulse 9, the 9th image is created.The video signals of the positive state of the pulse and the negative state of the pulse appear double due to the afterimage effect of the eye, but the two images are shifted in two rotational directions. Therefore, when the pattern is imaged by aligning it exactly with the deflection area, the alignment current supplied to the horizontal and vertical alignment coils is controlled so that the center of the pattern becomes one point. I was adjusting the alignment.

Therefore, conventional methods have relied on manual adjustment in this way, which has caused problems in equalizing the quality of the two images, such as individual differences appearing in the correction results.

In addition, in order to eliminate this drawback, the applicant of the present application has filed a correction method in Japanese Patent Application No. 135851/1983, in which the amount of deviation between the two images is automatically detected using a microprocessor, etc., and the beam alignment is corrected. . This takes an image of the adjustment test pattern in accordance with the deflection area, has a constant current source that supplies focus current to each focusing coil independently, and sets the focus current of the channel to be corrected by a fixed amount in the positive and negative directions. Detecting the phase difference between the center position of each video signal at a predetermined portion when the change occurs and the center position of the video signal (reference signal) of another channel,
The amount of correction is determined by calculation from each phase difference,
This controls the alignment current.

However, in this method of automatically correcting beam alignment, unlike the manual adjustment by nine people, the center position of the video signal of the channel to be corrected and the center position of the video signal of the channel to be corrected,
Since the part (reference point in the detection range) that detects the phase difference with the center position of the video signal is fixed (unchanging),
In the alignment correction control process, the center position of the video signal of the channel to be corrected appears to shift in the direction where the difference in deviation increases from the center position of the video signals of other channels, so the alignment correction control reaches the convergence point. As it approaches , it deviates from the part (reference point) where the phase difference is detected, and it falls within the detected amount of misalignment. The proportion of values showing deviation decreased, detection accuracy decreased, and it was difficult to converge within the tolerance.

In order to eliminate this drawback, the present invention improves detection accuracy by aligning the center position of the reference video signal and the correction channel with the reference part of the detection during phase difference detection in automatic beam alignment correction using a microprocessor, etc. The purpose is to This feature includes center position correction control in the beam alignment correction control procedure, and controls beam alignment correction while preventing the center position of the correction channel from shifting with respect to the reference signal.

FIG. 2 is a block diagram showing an embodiment of the present invention.

Here, explanation will be given taking the red channel as an example. Note that the same applies to other channels. 10 is a deflection coil, 11 is a focusing coil of the coil assembly for red color, 2 is an image pickup tube for red color, 12 is a vertical alignment coil, 13 is a horizontal alignment coil, 14°] 5 is a vertical alignment current control circuit, and horizontal alignment current, respectively. control circuit, 16
17 is a focus current control circuit; 17 is a multiplexer for selectively extracting 2-channel video signals from the red, blue, and green 3-channel video signal output; 18 is a phase difference for detecting the phase difference between these 2-channel video signals; Detector, 19 is a center position deviation detection circuit for detecting the center position deviation between the two channel video signals, 20 is a microprocessor, 21
is a control circuit for center position correction.

The pattern to be imaged here is one in which the phase difference of the video signal between two channels can be detected. (For example, if a 7-figure pattern is used, phase differences in both vertical and horizontal directions can be detected simultaneously, and horizontal and vertical alignment control amounts can be obtained simultaneously.) Next, the present invention will be explained in detail. This is the same as the application filed in the aforementioned Japanese Patent Application No. 135851/1983.

First, this alignment correction operation will be briefly explained.

The above-mentioned pattern is imaged in accordance with the deflection area, and the focus current control circuit 16 controls the red focus current (Fi) by a certain amount (△ε
) change in the positive direction (Fi+Δε).

At this time, the multiplexer 17 selects the red video signal and the green (or blue) video signal, and the phase difference detector 18 uses the portion (here, the 7th character corner of the 7th character pattern) that serves as the reference image between these video signals. horizontal and vertical phase difference ΔHFi+
△ε, △VFi+muε are detected.

Next, in the same way, the red focus current (F+) is changed by a fixed amount (△ε) in the negative direction (F+ - Δε), and the horizontal and vertical phase differences △HF1 - △ε, △VFi - △ε are similarly changed. To detect. Note that the detection of the phase difference between two video signals using a 7-character pattern is described in Japanese Patent Publication No. 53-39287, so a specific configuration will be described here.

The explanation of the operation will be omitted. Next, these detection outputs are supplied to the microprocessor 20, and this internal arithmetic circuit calculates the horizontal alignment deviation amount ΔA) (and the vertical alignment deviation amount ΔAv) using a linear equation.

△A)1=ΔHFi+△ε-(ΔHF1-△)...
・・・・・・(1)ΔAy=ΔVF i+Δε−(ΔV
Fi−Δε)・・・・・・・・・(2) flll, +2
After calculating the correction amount using Equation 1, the value is output to the vertical and horizontal alignment current control circuits 14 and 15. The above operations are repeated until the detected alignment deviation amounts ΔAH and ΔAv reach the tolerance, and when the tolerance is reached,
In response to a command from the microprocessor 20, the focus current control circuit 16 returns the focus current to its original value (
Return to Fl). Perform alignment correction for other channels in the same way.

Note that alignment deviation detection is performed by changing the focus voltage of the red channel to be controlled in a constant positive and negative direction, rather than using the focus current, and finding the phase difference with the video signal (reference signal) of the green (or blue) channel. , a method may be used in which the difference between these two values is calculated and used as the deviation amount. Next, the beam alignment correction method of the present invention will be explained. First, before performing the above-mentioned alignment deviation detection correction for the red channel, the center position deviation of the red channel with respect to the green (or blue) channel is detected by the center position deviation detection circuit 19, and the microprocessor 2
0, it is determined whether the center position deviates from the detection range at the time of detecting the alignment shift described above. If it is out of alignment, the deflection coil 10 is controlled via the center position correction control circuit 21 to align the center position with the reference signal.

Next, the aforementioned alignment shift detection for the red channel is performed. Correct the alignment of the red channel. Then, the center position of the red channel apparently deviates from the green channel (reference signal) in the direction in which the amount of deviation of the center position increases. That's no good.

Also, return to the first step and perform the center alignment control described above.

Repeat the alignment correction until the amount of alignment deviation becomes less than or equal to the set value. The same applies to other channels. Here, when detecting alignment deviation,
For the green channel, the blue (or red) channel,
In the case of the blue channel, when the video signal of the red (or green) channel is used as a reference signal, the same channel is used as the reference signal for center position detection.

As explained above, according to the present invention, in automatic alignment correction by a microprocessor.

Beam alignment correction control is possible without increasing the deviation of the center position.

The effects obtained by the present invention are (1) alignment correction can be performed without lowering detection sensitivity; and (2) therefore.

Since the detection range can be narrowed, a high-resolution detection system is not required, and highly accurate detection can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional alignment correction circuit, and FIG. 2 is a block diagram showing a correction method according to the present invention. 2: Image pickup tube, 12: Vertical alignment coil. 13: Horizontal alignment coil, 10: Deflection coil. 11: Focusing coil, 14: Vertical alignment current control circuit, 15: Horizontal alignment current control circuit, 16: Focus current control circuit, 17: Multiplexer. 18: Two-phase difference detector; 19: Center position deviation detection circuit. 20: Microprocessor; 21: Center position correction control circuit. Representative Patent Attorney Bo 1) Yuki Yi;

Claims (1)

[Claims] In the beam alignment correction of a multi-tube television camera in which each channel has a control circuit for controlling the focusing coil of the coil assembly, only the focusing coil of the channel to be corrected is alternately used to correct the beam alignment. control. Beam alignment determines the phase difference between the rotating video signal and the video signal of another channel (reference signal) at the center position of the reference object, calculates the difference between these two values, and determines the amount of beam alignment correction. A beam alignment correction method for a television camera, characterized in that the correction control procedure includes center position correction control of the beam alignment correction channel.