JPH0133077B2 - - 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 an electrostatic focusing multi-tube color television camera.

In the conventional manual beam alignment adjustment method, an image is captured by aligning the center of an adjustment test pattern (registration chart, etc.) with the center of an imaging plane, and the focus voltage is varied in positive and negative directions at a constant cycle. By changing the focus voltage,
It is known that images shift in the rotational direction around the beam axis, so images rotated when the focus voltage is changed in the positive direction and in the negative direction may be affected by the afterimage effect in the eye. , it appears to be doubled. Here, the two images are shifted in the direction of rotation, but if the beam alignment is adjusted correctly, the images rotate at one point with the center of the pattern as the center of rotation. Therefore, the alignment current is supplied to the horizontal and vertical alignment coils so that the center of the pattern is exactly aligned with the center of the imaging surface, and 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.

The present invention is a correction method aimed at automatically correcting beam alignment using a microprocessor or the like in order to eliminate this drawback.

This feature is equipped with a high-voltage generation circuit that supplies focus voltage independently to the third grid electrode of each image pickup tube. During beam alignment correction, a predetermined pattern is imaged, and only the focus voltage of the channel to be corrected is set to positive and The positions of the respective predetermined points corresponding to the respective predetermined point positions of the images moving in the opposite rotational directions and the corresponding predetermined point positions of the images of other channels as a reference are changed in the negative direction. Detecting the phase difference between video signals, calculating the amount of deviation in beam alignment based on these detected phase differences, and repeatedly controlling the beam alignment current of the correction channel until the calculated amount of deviation converges to a value within a predetermined range. It also performs beam alignment correction.

FIG. 1 shows 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. 1 is an image pickup tube, 2 is a vertical alignment coil, 3 is a horizontal alignment coil, 4,
5 is a constant current source that controls vertical and horizontal alignment currents, 6 is a high voltage generation circuit that supplies a focus voltage, 7 and 8 are vertical and horizontal alignment current control circuits, respectively, 9 is a focus voltage control circuit, and 10 is a a multiplexer that selectively extracts a two-channel video signal from the red, green, and blue three-channel video signal output; 11 a phase difference detector that detects the phase difference between the two channel video signals; 12 an analog-to-digital converter; 13 is a microprocessor, and 14 is a digital-to-analog converter. The test pattern to be imaged (not shown) is
A pattern (for example, a V-shaped pattern) that can detect the phase difference between the video signals between two channels is used. This pattern is imaged by aligning it with the center of the imaging surface, and the focus voltage control circuit 9 changes the red focus voltage by a certain amount in the positive direction in response to a command from the microprocessor 13. At this time, the multiplexer 10 selects a red video signal and a green (or blue) video signal (reference signal), and the phase difference detector 11 selects a red video signal and a green (or blue) video signal (reference signal) from these video signals. The phase difference corresponding to the horizontal and vertical positional deviation amounts ΔH ₊ and ΔV ₊ (FIG. 2) of the corners) is detected. Next, in the same manner, the red focus voltage is changed by a certain amount in the negative direction, and the phase difference corresponding to the horizontal and vertical positional deviations ΔH _- and ΔV _- (FIG. 2) is similarly detected. Regarding phase difference detection between two video signals using a V-shaped pattern,
Since it is described in Publication No. 39287, a description of its specific configuration and operation will be omitted here. after that,
These detection outputs are converted to analog/digital converter 1.
2, the internal arithmetic circuit of the microprocessor 13 calculates the horizontal misalignment amount ΔA _H and the vertical misalignment amount ΔA _V using the following equations.

ΔA _H = ΔH ₊ −ΔH _- ………(1) ΔA _V = ΔV ₊ −ΔV _– ………(2) After calculating the correction amount using equations (1) and (2), the digital-to-analog converter 14 The value is outputted to the vertical and horizontal alignment current control circuits 7 and 8 via.
Alignment deviation amount ΔA _V when the above operation is detected,
This is repeated until ΔA _H converges to a value within a predetermined range, and when it converges to a value within a predetermined range, the focus voltage control circuit 9 returns the focus voltage to its original value in response to a command from the microprocessor 13. Similar adjustments are made for other channels.

According to the method described above, all of this operation is replaced by a microprocessor, etc., making it possible to automatically adjust the alignment correction, and eliminating differences in correction results due to individual differences, which was a disadvantage of conventional manual adjustment. This greatly reduces adjustment time.

As explained above, according to the present invention, alignment correction can be performed by a microprocessor or the like instead of manually. The effects include (1) shortening of adjustment time, and (2) uniformity of adjustment results.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a correction circuit used in the correction method of the present invention, and FIG. 2 is an explanatory diagram showing the amount of alignment deviation. 1: image pickup tube; 2:
Vertical alignment coil, 3: Horizontal alignment coil, 4: Vertical alignment current source, 5: Horizontal alignment current source, 6: High voltage generation circuit for focus voltage supply, 7, 8: Vertical and horizontal alignment current control circuits, respectively, 9: Focus voltage control circuit, 10: phase difference detection circuit, 13: microprocessor.

Claims (1)

[Claims] 1. In an electrostatic focusing multi-tube color camera that has its own high-voltage generating circuit for each channel that generates a focus voltage to be supplied to the third grid of the image pickup tube, a predetermined pattern is imaged and corrected during beam alignment correction. By changing only the focus voltage of the channel by a certain amount in the positive and negative directions,
At this time, between each video signal corresponding to the amount of positional deviation between each predetermined point position of the image of the correction channel moving in the opposite rotational direction and the corresponding predetermined point position of the image of the other channel as a reference. detecting the phase difference between the two, calculating the amount of deviation in beam alignment based on these detected phase differences, and repeatedly controlling the beam alignment current of the correction channel until the calculated amount of deviation converges to a value within a predetermined range. Features a beam alignment correction method for television cameras.