JPH0414406B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a video signal processing device, which records and reproduces video signals field by field using a plurality of video heads provided at opposing positions on a rotating drum. It relates to a processing device.

Prior Art In a rotating head type magnetic recording/reproducing device in which a plurality of video heads are provided at predetermined intervals on a rotating drum,
High accuracy is required in the mounting position of multiple video heads in the rotational direction of the rotating drum (time accuracy ±
0.2μs, dimensional accuracy 1.2μm). This is not a particular problem when recording and reproducing are performed using the same device, but when recording and reproducing are performed using devices with video heads installed in different positions, image distortion occurs.

Therefore, in the past, a delay circuit was used to delay the playback signal from one video head or the recording signal supplied to the other video head by an amount corresponding to the error in the rotational direction of the rotating drum of the video head. A device is being considered that reproduces or records the recorded information. By adjusting the delay amount of this delay circuit in accordance with the video head installation error in each device, it is possible to extract a reproduced signal and a recording signal that are not affected by the video head installation error.

Problems to be Solved by the Invention However, configuring a general delay circuit (consisting of L and C) that handles analog signals so that it can be varied by increasing the delay time makes the circuit complicated. In addition, it is difficult to create a delay circuit using a CCD.
When constructing this system, there was a problem that it could not handle analog signals in a wide frequency band, making it difficult to implement.

Means for Solving the Problems The present invention provides an AD conversion means for converting an incoming signal into a digital signal, a delay amount setting means for arbitrarily setting the delay amount variably by external operation, and an AD conversion means for converting an incoming signal into a digital signal. Delay means for outputting only the output corresponding to one video head after being delayed by an amount set by the delay amount setting means in response to video head switching, and a delay means for processing the output of the delay means and converting it into an analog signal. The above problem is solved by a configuration consisting of a means for converting and extracting the video head, and a means for measuring the mounting error of the video head in advance and externally setting the delay amount for correcting the mounting error as data. One embodiment will be described with reference to the drawings.

Examples In recent years, television receivers that digitally process television signals and display images have been developed (for example, "Nikkei Electronics" 1981, 11).
23, pp. 233-247), digital signal processing in this way makes it easier to use LSIs than analog signal processing, which reduces the number of parts, and also reduces the number of parts used in various circuits. Since the adjustment can be realized by data processing, there are advantages such as simplifying the adjustment work.

The present invention applies the concept of digital signal processing of television signals to a rotary head type magnetic recording and reproducing device, and configures the delay circuit with a programmable delay circuit, and sets the delay amount variably according to the video head installation error. The arrangement is such that a television signal is obtained that is not affected by the video head installation error.

FIG. 1 shows a block system diagram of an embodiment of a video signal processing apparatus according to the present invention. During playback, switches 2 and 3 are activated by the control signal from the recording/re-switching circuit 1.
is connected to terminal P. First channel video heads 4 mounted on a rotating drum at 180° intervals
a, the video signal reproduced from the magnetic tape 5 by the second channel video head 4b is sent to the amplifier 6a,
6b, and is switched every 180° rotation by the switch circuit 8 by the drum pulse taken out according to the rotation of the rotating drum that enters the terminal 7,
The signal is supplied to the AD converter 9 via the switch 2.

The reproduced video signal converted into a digital signal by the AD converter 9 is transmitted to the programmable delay circuit 1, which will be described later.
0 memory 11 and then read out, the video signal processing circuit 12 generates a well-known luminance FM signal.
Operations such as carrier color signal separation, FM demodulation, carrier color signal frequency conversion, APC, and ACC are performed by digital signal processing. The signal taken out from the video signal processing circuit 12 is converted into an analog signal by the DA converter 13, and taken out as a video signal from the output terminal 14 via the switch 3.

Here, as shown in FIG. 2, the video heads 4a and 4b are attached to a rotating drum 15 rotating in the direction of the arrow with a certain attachment error Δθ, and in this device a standard magnetic tape (a device in which the video head attachment position is normal) is attached. 5) is played back. For example, if a magnetic tape 5 on which a signal is recorded that displays a vertical bar on the playback screen (for example, a thin vertical bar on head 4a and a thick vertical bar on head 4b) is played back by a device with a head installation error, the first field and the first field The position of the vertical bar on the playback image is different in the horizontal direction between the two fields, and the receiver has AFC operation, so the playback screen is the vertical bar B 1 shown in Figure 3A in the first field, and the vertical bar B ₁ shown in Figure 3A in the second field. The vertical bar _B2 shown in FIG. 3B is displayed, and the originally vertical vertical bar is displayed with a distortion of an error Δl.

This error Δl corresponds to the installation error Δθ of the video head 4a in FIG. 2, and the adjuster judges which head should be adjusted by looking at the thickness of the vertical bar on the playback screen. The optimum value is input to the programmable delay circuit 10 by operating the key switch 16 so that the error Δl is eliminated (that is, so that the vertical bar is correctly vertical). This optimum value means that the head 4a in FIG. 2 is substantially the same as the head 4b.
This value is to be the same as when the head 4a is installed at a position 4a' with a 180° interval between the head 4a and the head 4b. The signal from key switch 16 is
The signal is supplied to a rewritable memory 17 such as a RAM, where it is converted into a control signal having a predetermined address, and is supplied to a coincidence detector 18.

On the other hand, the output of the AD converter 9 is sent to the memory 11 according to the write control signal from the write address counter 19.
The reproduced video signal written in the memory 11 is read out from the memory 11 in accordance with a read control signal from the read address counter 20. At this time, the write address counter 1 is detected by the coincidence detector 18.
9 and the signal from the memory 17 are constantly compared, and when these two signals match, a coincidence detection signal is taken out from the coincidence detector 18 and supplied to the read address counter 20. starts counting.

As a result, although the reproduced signal from the head 4a taken out from the AD converter 9 is written into the memory 11, it is delayed by the delay amount set in the memory 17 and then read out. On the other hand, the reproduced signal from the head 4b taken out from the AD converter 9 is read out immediately after being written into the memory 11. This head 4a and head 4b
The reproduction signal is switched between delayed and non-delayed in response to a switching signal from a polarity switching signal generator 21 which is supplied with drum pulses every 180° from the terminal 7.

In this way, the adjuster looks at the playback screen and operates the key switch 16 to set the delay amount of the playback signal of the head 4a so that the error Δl is eliminated. The same signal is obtained as if the signal is at a position with an interval of B can be displayed.

On the other hand, in the recording mode, the delay amount set during playback is inserted into the operation period of the video head on the opposite side with the same value. That is, head 4
The signal to be recorded on the head 4b has a delay of zero, and the signal to be recorded on the head 4b has a delay of 3 μs, for example, corresponding to Δθ in FIG. Switches 2 and 3 are connected to terminal R by a control signal from recording/re-switching circuit 1.

The video signal that enters the terminal 22 is supplied via the switch 2 to the AD converter 9, where it is converted into a digital signal, and then supplied to the memory 11, where the head 4a corresponds to the unrecorded magnetic tape 5'. When the delay amount is zero, when the head 4b corresponds to the unrecorded magnetic tape 5', it is delayed by the set delay amount and taken out, and then the video signal processing circuit 12 processes the brightness, color signal separation, AGC, emphasis, and FM modulation. , color signal frequency conversion, and other necessary operations are processed using digital signals. As a result, the original position 4 in FIG.
What is recorded by the head at b' can be recorded by the head 4b with a delay corresponding to Δθ, and the signal can be recorded without being affected by installation errors.

The clock pulses of the AD converter 9, write address counter 19, and read address counter 20 are set to 14M.
Hz and can be adjusted in 100 steps, it is possible to set a delay time of (1/14) x 100 = ±7 μs, and to correct an installation error of ±40 μm in terms of dimensions.

When replacing the video head, play back the standard tape, measure the error again, and calibrate the delay amount.

Furthermore, it is also possible to automatically detect errors from the horizontal synchronization signal of the reproduced signal without looking at the screen.

Furthermore, the present invention is not limited to a two-head system, but can be similarly applied to a four-head system in which each head has its own dedicated head in the standard mode and long-time mode. It is stored in the memory 17 and used depending on the mode.

Effects As described above, the video signal processing device according to the present invention is an AD converter that converts an incoming signal into a digital signal.
A conversion means, a delay amount setting means for arbitrarily setting the delay amount variably by external operation, and a delay amount setting means for setting only the output corresponding to one video head among the outputs of the AD conversion means in response to switching of the video head. a delay means for extracting the output after a delay of a set amount by the means; a means for converting the output of the delay means into an analog signal after signal processing; and a delay means for measuring the mounting error of the video head in advance and correcting the mounting error. Since it is a means of externally setting the amount of data as data, by setting the delay amount according to the installation error of the video head and continuously using that delay amount, the video signal can be continued without being affected by the installation error. There is no need to change the set delay amount unless you change the video head and change the delay amount depending on the video head during recording and playback. It has the advantage of being able to obtain video signals that are unaffected by installation errors both during playback and during playback.

[Brief explanation of drawings]

Fig. 1 is a block system diagram of one embodiment of the device of the present invention, Fig. 2 is a diagram for explaining the mounting error of the video head on the rotating drum, and Figs. This is the playback screen that appears. 1... Recording/re-switching circuit, 2, 3... Switch,
4a, 4b... Video head, 5, 5'... Magnetic tape, 7... Drum pulse input terminal, 8... Switch circuit, 9... AD converter, 10... Programmable delay circuit, 11, 17... memory, 12
...Video signal processing circuit, 13...DA converter, 1
4... Output terminal, 15... Rotating drum, 16...
Key switch, 18... Coincidence detector, 19... Write address counter, 20... Read address counter, 21... Polarity switching signal generator, 22... Video signal input terminal.

Claims (1)

[Scope of Claims] 1 AD that converts incoming signals into digital signals in a video signal processing device that records and reproduces video signals field by field using a plurality of video heads provided at opposing positions on a rotating drum. a conversion means, a delay amount setting means for arbitrarily setting the delay amount variably by an external operation, and a delay amount setting means for controlling only the output corresponding to one of the video heads among the outputs of the AD conversion means in response to switching of the video heads. A delay means for delaying the output by an amount set by the delay amount setting means, a means for processing the output of the delay means and converting it into an analog signal and taking it out, and a means for measuring the installation error of the video head in advance and determining the installation error. What is claimed is: 1. A video signal processing device comprising means for externally setting a value of a delay amount for correcting the delay amount as data. 2. A video signal processing device that records and reproduces video signals field by field using a plurality of video heads installed at opposing positions on a rotating drum, which includes AD conversion means for converting incoming signals into digital signals, and external operation. delay amount setting means for arbitrarily setting the delay amount variably according to the output of the AD conversion means; and among the outputs of the AD conversion means, only the output corresponding to one video head during playback and the output corresponding to the other video head during recording. a delay means for extracting only the output corresponding to the video head after delaying it by an amount set by the delay amount setting means; a means for converting the output of the delay means into an analog signal after signal processing; A video signal processing device comprising means for measuring an installation error and externally setting a delay amount for correcting the installation error as data.