JPH0115260Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the electron beam focusing state of an image pickup tube of a color television camera.

In conventional color television cameras, in order to reduce the difference in resolution between the center and periphery of the screen, parabolic waveform signals for horizontal and vertical correction are added to the voltage applied to the electrodes forming the electron lens of the image pickup tube. A method called dynamic focus was used to add . This dynamic focus had the following problems.

1 Generally, resolution deterioration at the periphery of the screen is not symmetrical with respect to the center, and there are differences between the left and right, top and bottom. Simply adding a parabolic signal as in the conventional method may actually worsen this problem depending on the part.

2. In the case of a three-tube color camera, a correction signal is added to each of the R, G, and B channels separately, resulting in poor registration.

In order to eliminate these drawbacks, the present invention uses the added correction waveform signals as waveforms corresponding to each of the four corners of the screen, and controls these separately. Furthermore, in an R, G, B three tube type color camera, in order to prevent deterioration of registration, the same correction waveform signals at each of the four corners are applied to each of the three tubes.

This will be explained below with reference to the embodiments shown in the figures. In the figure, reference numeral 1 denotes a correction waveform generation circuit which generates parabolic correction waveform signals independent of the four corners that match the times in electron beam scanning corresponding to the four corners of the output image. This signal is subjected to level control by a level controller 2, and then inputted to a distributor 3 at each of the four corners. Then, each distributor 3 divides the signal into three systems of R, G, and B signals, which are added to the DC high voltage generation circuit 4. The output voltage passing through the DC high voltage generating circuit 4 becomes a DC signal superimposed with each correction waveform signal, and is applied to the electrodes forming the electron lens of each image pickup tube 5. In the case of a typical electromagnetic focusing and electromagnetic deflection image tube, this application electrode is the electrode designated G3.

With the above configuration, by controlling the controller 2 in response to a decrease in the resolution of each periphery of the screen, the resolution of the periphery can be set to an optimal state.
Furthermore, by changing the control level of these controllers 2, the geometric distortion of the output image generally changes, but if a common correction signal is added to the three R, G, and B image pickup tubes as in this method, Even if you set an adjuster that supports the four corners to improve peripheral resolution,
Since the image distortion of each of the R, G, and B channels changes in the same way, the registration does not deteriorate.

As explained above, according to the present invention, it is possible to improve the peripheral resolution of the screen without deteriorating the registration, so it is effective when applied to multi-tube color television cameras that require high resolution. It's large.

[Brief explanation of the drawing]

The figure is a block diagram according to one embodiment of the invention. 1: Correction waveform generation circuit, 2: Level controller,
3: Distributor, 4: DC high voltage generation circuit, 5: Image pickup tube.

Claims (1)

[Scope of utility model registration request] A multi-tube color television camera includes a correction waveform generation circuit that generates parabolic correction waveform signals independent of the four corners that match the times in electron beam scanning corresponding to the four corners of an output image, and a correction waveform generation circuit that outputs the output to each of the four corners. A level adjuster for corresponding level control,
A peripheral resolution correction circuit comprising: a distribution and synthesis circuit for commonly applying each of the above correction waveform signals to the electrodes forming the electron lens of each image pickup tube to each of the image pickup tubes.