JPH0149073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a device for generating an erasable cue signal.

<Prior art> Conventionally, writing a cue signal onto a videotape involves
A full-width tape erasing head is used to erase the entire width of the tape, crossing the video signal track, as shown by the hatching in FIG. However, with this method of writing cue signals, when the reproduction magnetic head passes through the cue signal portion, bar noise appears in the reproduced image, and when erasing the cue signal, the image of the portion overlapping with the cue signal appears. The disadvantage is that the signal is also erased.

<Object of the invention> The object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an erasable cue signal in which a magnetic head for video image recording also serves as a magnetic head for writing and erasing cue signals. The purpose is to provide a generator.

<Structure of the Invention> In order to achieve the above object, an apparatus according to the present invention includes: a cue signal generating means for generating a cue signal fixed at a predetermined level near the black level of a video image signal; a signal delay circuit that outputs a delayed video image signal after being delayed by a predetermined number of fields; a switch means that selects any one of the video image signal, the queue signal, and the delayed video image signal; It has cue signal write/erase timing means for generating a signal for driving this switch means.

<Example> Next, an example of the present invention will be described based on the drawings. FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, in which the video image signal input from terminal 1 is
The line is divided into a line that goes directly to contact b of the switch 6, a line that goes to the 1-foot delay circuit 3, and a line that goes to the synchronizing signal separation circuit 2. The one-field delay circuit 3 outputs a signal obtained by delaying the video image signal by one field. The synchronization separation circuit 2 separates and outputs a synchronization signal component from the video image signal. The synchronization signal is input to the queue signal generator 4 and the queue signal write/erase timing means 5. The cue signal generator 4 always generates a cue signal fixed at the black level. In the above, normally, the switch 6 is on the contact b side, and the video image signal is processed through the luminance signal processing circuit 7 and the color signal processing circuit 8, amplified by the amplifier circuit 9, and then outputted from the magnetic head to the video signal. recorded on tape.
At the timing when a cue signal should be recorded (for example, immediately after the start of recording or immediately after canceling the recording pause), a signal is emitted from the cue signal writing/erasing timing means 5, and the switch 6 closes the contact only during one field of the video image. As shown in FIG. 3, the switch 6 outputs a video signal including a cue signal for one field (portion d in the figure) in the middle. This cue signal passes through the luminance signal processing circuit 7, and is sent to one of the video signal tracks from the same magnetic head 10 as the recording magnetic head, as shown by the symbol in FIG.
Only the field is recorded. Since the cue signal is recorded for only one field, it does not visually affect the image when it is played back from this videotape.

In addition, when erasing this written queue signal, the switch 6 is switched to the contact a side by the queue signal write/erase timing means 5, and the switch 6 is switched to the contact a side.
An image of one field before the screen corresponding to the cue signal position, which is stored in the field delay circuit, may be recorded in the cue signal portion. The duplication of one field's worth of video does not affect visual perception during video playback.

Note that the video recorded on the videotape and the queue signal can be reproduced by an apparatus having a circuit configuration as shown in FIG. The video signal component in the video signal picked up by the magnetic head 10 is processed by the signal demodulation circuit 12 and the color signal demodulation circuit 13, and then output as a video signal to the terminal 15. On the other hand, the cue signal component is processed by the signal demodulation circuit 12 and the color signal demodulation circuit 13, and then outputted to the terminal 15 as a video signal. The signal is sent to terminal 15 and queue signal detection circuit 14 through the circuit. The cue signal component reaching the terminal 15 is mixed with the video signal and outputted without affecting the visual sense, as described above, and the component input to the cue signal detection circuit is sent to the terminal 16 as a detected cue signal.
It is output from

In the above description, the writing width of the cue signal is only for one field of video, but it goes without saying that an apparatus may be configured to write for multiple fields as long as it does not affect the visual sense.

<Effects of the Invention> As is clear from the above description, according to the present invention, cue signals can be written and erased using a magnetic head for video recording without affecting the visual sense. , an erasable cue signal generator is provided.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a queue signal writing pattern according to the prior art. FIG. 2 is a block diagram showing the circuit configuration of the embodiment of the present invention, FIG. 3 is an explanatory diagram of the operation of the same embodiment, and FIG. 4 shows the pattern of the queue signal written by the device according to the above embodiment. It is a diagram. FIG. 5 is a block diagram showing the circuit configuration of means for reproducing video signals recorded by the apparatus of this embodiment. 2... Synchronization signal separation circuit, 3... Video signal 1 field delay circuit, 4... Queue signal generation circuit,
5...Queue signal write/erase timing circuit, 6
...changeover switch.

Claims (1)

[Claims] 1. A cue signal generating means for generating a cue signal fixed at a predetermined level near the black level of the video image signal, and a signal delay device for delaying the video image signal by a predetermined number of fields and outputting a delayed video image signal. a circuit, a switch means for selecting any one signal from the video image signal, the queue signal, and the delayed video image signal, and a queue signal write/erase for generating a signal for driving the switch means. an erasable cue signal generator having timing means;