JPH0133078B2 - - Google Patents

Description

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

There are two types of television cameras: electromagnetic focusing type and electrostatic focusing type. FIG. 1 shows a focus current supply circuit of a conventional electromagnetic focusing three-tube camera. Here, 2, 4, and 6 are image pickup tubes for red, green, and blue, respectively, and 1, 3, and 5 are for red, green, and blue, respectively.
This is a coil assembly for green and blue. 7 is
A constant current source 8 that generates a focus current to be supplied to the focusing coil of the coil assembly is a focus current control circuit.

This focus current generated by the constant current source 7 is supplied to the focusing coils of the coil assemblies 1, 3, and 5 for red, green, and blue colors connected in series.

In the conventional manual beam alignment adjustment method, an image is taken with the center of an adjustment test pattern (registration chart, etc.) aligned with the center of the imaging plane, 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 a constant period. It is known that when the focus current changes, the image shifts rotationally around the beam axis, so by adding this pulse 9, the image changes to the image of the positive state of the pulse and the negative state of the pulse. The signal appears to be doubled due to the eye's afterimage effect, but since the two images are shifted in the direction of rotation, only the center of rotation appears to be a single point. Therefore, the center of the pattern is aligned exactly with the center of the imaging surface, and the alignment current supplied to the horizontal and vertical alignment coils is adjusted so that the center of the pattern is at one point (the center of rotation). By controlling the beam axis, the beam axis was aligned with the center of the imaging plane and the beam alignment was adjusted.

In this way, conventional methods have relied on manual adjustment, which has caused problems in terms of uniformity of image quality, such as individual differences in the correction results.

In addition, in order to eliminate this drawback, the applicant has applied for a correction method in which a microprocessor or the like automatically detects the amount of deviation between the two images and corrects the beam alignment in Japanese Patent Application No. 135851/1983. did. This system is equipped with a constant current source that independently supplies a focus current to each focusing coil, and when correcting beam alignment, images a predetermined pattern and changes only the focus current of the channel to be corrected by a fixed amount in the positive and negative directions. , at this time, the phase difference between each video signal corresponding to the amount of positional deviation between each predetermined point position of each image moving in the opposite rotational direction and the corresponding predetermined point position of the image of another channel as a reference. is detected, the amount of deviation in beam alignment is calculated based on these detected phase differences, and the beam alignment current of the correction channel is repeatedly controlled until the calculated amount of deviation converges to a value within a predetermined range, and beam alignment correction is performed. It is something to do.

However, in this method of automatically correcting beam alignment, unlike manual adjustment,
As shown in the figure, the detection range (detection position) for detecting the amount of positional deviation between the predetermined point positions R ₁ and R ₂ of the image of the channel to be corrected and the predetermined point position G ₀ of the image of the other channel as a reference is fixed (unchanged), but if the beam alignment current is controlled in the alignment correction control process and the beam axis B _R of the correction channel is aligned with the center T _C of the imaging plane, the correction channel apparently changes. The predetermined point positions R′ ₁ and R′ ₂ of the image deviate from the reference predetermined point position G ₀ of the images of other channels in the direction where the difference in deviation increases, so as the alignment correction control approaches the convergence point, the position The amount of misalignment may fall outside the detection range, and the value indicating the misalignment during detection of the amount of alignment misalignment may be inaccurate or cannot be obtained, resulting in a decrease in detection accuracy and the amount of misalignment falling within the predetermined range. It was difficult to control the convergence.

In order to eliminate this drawback, the present invention provides that, in automatic beam alignment correction using a microprocessor or the like, each image corresponding to the amount of positional deviation at a predetermined point position corresponding to a reference image and an image of a correction channel, respectively. The purpose of this method is to improve detection accuracy by controlling the corrected channel image so that it does not fall outside the detection range when detecting the phase difference between signals. This feature is
Centering correction control is included in the beam alignment correction control procedure, and beam alignment correction is controlled while preventing the predetermined position of the correction channel from shifting from the reference predetermined point position of the channel. .

FIG. 2 is a block diagram showing one embodiment of the present invention. Here, we will explain the red channel of an electromagnetic focusing three-tube camera as an example. Note that the same applies to other channels. 10 is a deflection coil, 11
is the focusing coil of the coil assembly for red color, 2 is the image pickup tube for red color, 12 is the vertical alignment coil,
13 is a horizontal alignment coil, 14 and 15 are a vertical alignment current control circuit and a horizontal alignment current control circuit, respectively, 16 is a focus current control circuit, and 17 is a 2-channel video signal output selectively from the 3-channel video signal output of red, blue, and green. The multiplexer 18 that takes out the signal is a phase difference detector 1 that detects the phase difference between the two channel video signals.
9 is a center position deviation detection circuit for detecting a center position deviation between the two channel video signals; 20 is a microprocessor; and 21 is a center position correction control circuit. The pattern to be imaged here is one that can detect the video signal phase difference between the two channels. (For example, if a V-shaped 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 operation of the present invention will be explained. Regarding that matter, please refer to the above-mentioned patent application in 1982.
Since it is the same as that filed in No. 135851, this alignment correction operation will be briefly explained first.
The above pattern is imaged by aligning it with the center of the imaging plane, and the focus current control circuit 16 changes the red focus current (Fi) by a certain amount (△ε) in the positive direction according to a command from the microprocessor 20 (Fi+△). ε). 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 V-shaped corner of the V-shaped pattern) that serves as the reference image between these video signals. horizontal and vertical positional deviation amount _ΔFi +Δε,
A phase difference corresponding to ΔV _Fi +Δε (Fig. 3) is detected. Next, in the same way, the red focus current (Fi) is changed by a constant amount (Δε) in the negative direction (Fi − Δε), and similarly, the horizontal and vertical positional deviation amount ΔH _Fi −Δε,
A phase difference corresponding to ΔV _Fi −Δε (Fig. 3) is detected. Incidentally, the detection of the phase difference between two video signals using a V-shaped pattern is described in Japanese Patent Publication No. 39287/1983, so a detailed explanation of the configuration and operation will be omitted here. Next, these detection outputs are supplied to the microprocessor 20, and in this internal arithmetic circuit,
The horizontal alignment deviation amount △AH and the vertical alignment deviation amount △A _V are calculated using the following formula.

△A _H = △H _Fi +△ε−(△H _Fi -△ε) ………(1) △A _V = △V _Fi +△ε−(△V _Fi -△ε) ………(2) After calculating the correction amount using equations (1) and (2), 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 ΔA _H and ΔA _U converge to values within a predetermined range. When they converge to values within a predetermined range, the focus current control circuit 16 receives a command from the microprocessor 20. , returns the focus current to its original value (Fi). Perform alignment correction for other channels in the same way. In addition, in the case of an electrostatic focusing camera, detection of alignment deviation is carried out by changing the focus voltage of the red channel to be controlled by a certain amount to positive or negative, instead of the focus current, and detecting the video signal of the green (or blue) channel ( A method may also be used in which the phase difference with respect to the reference signal) is determined, and the difference between these two values is calculated and used as the amount of deviation. Next, the beam alignment correction method of the present invention will be explained. First, before performing the above-mentioned alignment deviation detection correction of the red channel, the center position deviation (centering 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 center position deviation is detected by the microprocessor 20. Then, it is determined whether the V-shaped pattern image of the red channel is out of the detection range at the time of the alignment shift detection described above. If it is out of alignment, the deflection coil 10 is controlled via the center position correction control circuit 21 to perform centering adjustment to align the V-shaped pattern image position of the red channel with the V-shaped pattern image position of the green channel.

Next, the above-described misalignment detection of the red channel is performed, and the alignment of the red channel is corrected. Then, as shown in Fig. 3, the predetermined point positions R' ₁ and R' ₂ of the red channel image appear to be
shifts in the direction in which the amount of shift from the predetermined point position G ₀ of the green channel image increases.

Therefore, the process returns to the first step and performs the above-described centering control of the red channel to align the red channel image with the green channel image position within the detection range.

The above centering control and alignment correction are repeated until the amount of misalignment converges to a value within a predetermined range.
The same applies to other channels. Here, when detecting alignment deviation, if the video signal of the blue (or red) channel is used as the reference signal in the case of the green channel, and the video signal of the red (or green) channel in the case of the blue channel, the reference signal for center position detection is also the same. channel.

As described above, according to the present invention, beam alignment correction control can be performed without increasing the deviation of the center position in automatic alignment correction using a microprocessor.

The effects obtained by the present invention are (1) alignment correction can be performed without reducing detection sensitivity, (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 drawings]

FIG. 1 is a conventional alignment correction circuit, FIG. 2 is a block diagram showing the correction method of the present invention, and FIG. 3 is a diagram illustrating the state of deviation in beam alignment. 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: phase difference detector, 19: center position deviation detection circuit, 20: microprocessor,
21: Center position correction control circuit.

Claims (1)

[Claims] 1. In beam alignment correction of a multi-tube television camera in which each channel has its own control circuit for controlling focus current or voltage, when correcting beam alignment, a predetermined pattern is imaged and the focus current or voltage of the channel to be corrected is and thereby alternately control the respective predetermined point positions of the images of the correction channel that move in mutually opposite rotational directions and the respective positions of the corresponding predetermined point positions of the images of the other channels as a reference. Detect the phase difference between each video signal corresponding to the amount of deviation, calculate the amount of beam alignment deviation based on these detected phase differences, and repeat the above correction until the calculated deviation amount converges to a value within a predetermined range. A beam alignment correction method for a television camera, characterized in that a beam alignment correction control procedure for controlling a beam alignment current of the channel includes center position correction control of the beam alignment correction channel.