DE1051318B - Method and arrangement for reducing the flicker of television pictures - Google Patents

Description

GERMAN

The invention relates to a method and arrangements for reducing the flickering of television images, especially of large projection images.

When playing television pictures with great brightness, the flicker is much stronger Dimensions noticeable than with normal brightness. This is particularly true for large projection images.

To reduce the flicker of large projection images, it has already been proposed that To change grid frequency. However, this requires a change in the entire television standard and therefore leads to considerable trouble.

For displaying still images that are slowly scanned and transmitted over a telephone line on a picture tube it is already known to store the picture signal on a magnetic tape and from take it off several times at increased speed. The recording and pick-up of the image signal takes place in different facilities.

For magnetic recording of television signals, it is also already known to reduce the speed of the magnetic tape to move the recording heads in the opposite direction to the tape movement.

For sound recording and playback, it is known to have multiple rotary pick-up heads and the like To move magnetic tape against each other in such a way that the relative speed between the sound carrier and Pick-up head remains constant in order to expand or contract the sound while maintaining the pitch of the To achieve sound absorption.

The present invention solves the problem of the flicker of television pictures, in particular large projection pictures by changing the screen frequencies without making a change the television standard is required by according to the invention each television picture on an endless magnetizable Carrier recorded and then recorded by one or more relative to the recording head removal head (s) moved against the direction of travel of the carrier removed several times and the or is fed to the picture tube (s).

Although this method does not increase the image information, it does increase the decrease period for a field divided into two or more periods similar to a reproduction of film frames and thereby the flicker is significantly reduced.

In a preferred arrangement for carrying out the method according to the invention, the is magnetizable Carrier attached to the periphery of a rotating disk. The recording and erasing heads are fixed side by side, while the removal head is opposite to the direction of rotation Disc rotates.

Procedure and arrangement

to reduce flicker

of television images

Applicant:

TV G.m.b.H.,

Darmstadt, Am Alten Bahnhof 6

Dipl.-Phys. Hellmut Preisher, Stuttgart-Sillenbuch,

and Dipl.-Phys. Theo Grünewald, Karlsruhe (Bad.),

have been named as inventors

In order to avoid a disturbance of the acceptance by the recording and To avoid the erase head, according to a further development of the invention, two are mechanical Coupled pick-up heads are used, which are alternately keyed or blocked.

The object on which the invention is based

Reducing the flicker of television pictures can also be solved in a slightly different way will. The two mechanically coupled pick-up heads are held in a certain position and constantly pick up a signal. Two picture tubes, whose pictures can be optically combined, or a picture tube with two beam systems used. Either of the two Picture tubes or beam systems are controlled by a pick-up head controlled. It is achieved that at the same time a complete, all lines containing TV picture can be recorded or played back. In this case, too, there is also the Possibility to move the pick-up heads against the direction of movement of the carrier.

The invention will now be explained in more detail with reference to the figures representing an exemplary embodiment will. All the details that are not absolutely necessary for an understanding of the invention are shown in the figures omitted.

Fig. 1 shows schematically an arrangement for performing the method according to the invention,
Fig. 2 is a timing diagram.

The arrangement consists essentially of a disk 1, on the circumference of which a magnetic tape 2 is attached is. The disc rotates in the direction of the arrow with such a number of revolutions that on its circumference just recorded the image signals for two partial images

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be drawn. With fifty fields per second, this means a speed of rotation of 1500 rpm. The recording is performed by the recording head 3 while the erasing is performed by the erasing head 4. The two mechanically coupled pickup heads 5 and 6 are provided for picking up the recorded image signal. At the time t _v as shown in Fig. 1 under α , three quarters of the first field (I) have already been recorded on the magnetic tape 2, and the pickup head 5 begins to read the video signal. At this point in time, the removal head 6 is blanked. Both pick-up heads move in the opposite direction to the rotation of disk 1 at the same speed of rotation as tape 2. Up to about time i ₂ , pick-up head 5 has completely scanned the first partial image, and it is switched off at this moment. The pick-up head 6 is now switched on and it scans the same partial image up to approximately the point in time t _z , which is shown in FIG. 1 under c . During this time, the pickup head 5 is moved on a path 7 which lifts it so far from the magnetic tape that it bypasses the recording head 4 and the pickup head 6 unhindered. During the double scanning of the first field, the recording of the second field was already started. The acceptance head 6 remains open beyond the point in time i _s and scans the second partial image completely up to approximately the point in time t _i. It is then switched off and also guided past the recording and erasing head on the path 7, while the pickup head 5 begins to record the signals for the second field.

The time relationships are shown in FIG. 2, with diagram e showing the time process during the recording of the individual partial images. Diagram / shows the scanning pulses for the pick-up head 5 and chart g the scanning pulses for the pick-up head 6, indicating which partial image is picked up in a certain period of time.

The invention is neither limited to the specified number of image changes nor to the number of pick-up heads. but can be modified accordingly without going beyond the scope of the invention will. For example, in an arrangement according to FIG Fig. 1 make the angular speed of the pick-up heads are doubled.

Claims (8)

PATENT APPLICATIONS: 1. Method for reducing the flickering of television images, in particular large projection images, characterized in that each television picture on an endless magnetizable Recorded carrier and immediately thereafter by one or more relative to the recording head Removal head (s) moved against the direction of travel of the carrier removed several times and the picture tube (s) is fed. 2. Arrangement for performing the method according to claim 1, characterized by a rotating Disc on the circumference of which the magnetizable carrier is located. 3. Arrangement according to claim 2, characterized in that the disc at such a speed is rotated so that two fields are recorded on its circumference. 4. Arrangement according to claim 2 and 3, characterized in that two pick-up heads are used that are mechanically coupled to each other and at the same speed as the magnetizable carrier, but are moved in the opposite direction as this. 5. Arrangement according to claim 4, characterized in that the two pick-up heads alternately in each case for the duration of a partial image ■ be keyed or locked. 6. Arrangement according to the preceding claims, characterized in that recording and erase heads are arranged close together and the removal heads during the blanking times are lifted so far from the magnetizable carrier that the recording and erasing head pass unhindered. 7. Arrangement according to claim 4, modified to the effect that the pick-up heads in a certain Position are recorded and each acceptance head has its own picture tube or system is assigned to a multi-beam tube. 8. An arrangement according to claim 7, characterized in that the number of pick-up heads is one is a whole multiple of the number of picture tubes or beam systems and opposed to the pick-up heads the direction of movement of the carrier. Considered publications:
German patent applications S 1258 VIII a / 21 a (published on February 15, 1951), D 6581 VIII a / 21 a (published on November 12, 1953); "Radio-Magazin", No. 12, 1952, pp. 379 and 380; "Looking around in science and technology", 1953, P. 247. 1 sheet of drawings © «09767/196 2.59