JPH01277352A - Rotary head type recording and reproducing device - Google Patents

Abstract

PURPOSE:To surely record control pulses and to completely attain servo even in case of reproducing at the time of starting tape winding by automatically recording pictures in a two-hour mode only for several seconds from the start of tape winding. CONSTITUTION:At the starting end of a tape, a tape starting end detecting signal is latched from a tape starting end detecting circuit 3 to a timer circuit 4, and when an REC switch on an operation switch 6 is depressed, a VTR is turned to a recording mode. Simultaneously with the mode switching, a tape starting end signal High is sent from the timer circuit 4 to a time mode switching circuit 5 for several seconds and a 2H High signal is sent from the circuit 5 to a control circuit 7 in stead of a 480H high signal to switch the current mode to a recording mode with time mode 2H. After several seconds, the 2H mode is restored to the 480H recording mode. Consequently, control pulses can be prevented from being overwritten and complete servo can be attained even in case of reproducing at the starting end of the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotating head type recording and reproducing device, and particularly to a device used for monitoring and security purposes.

Conventional technology surveillance VTRs are capable of long-time recording by frame-by-frame recording of video. Therefore, in recent years, it has become widely used for monitoring financial institutions and mandarins.

Hereinafter, an example of the above-mentioned conventional time-lag VTR will be described with reference to the drawings.

FIG. 2 shows a block diagram of the Time Lagase VTR, and numeral 8 denotes an erasing head that erases the entire width of the tape during recording. 9 is a rotary head for recording video signals. 1o
is an A/C that records and plays audio signals and control pulses.
It is the head. 11 is a capstan that feeds the tape at a constant speed.

12 is a video tape.

Regarding the Time Lage VTR configured as above,
The operation will be explained below.

First, in the 2-hour recording mode, the tape is continuously fed by the capstan 11, and a video signal is transmitted by the rotating head 9 to the portion of the tape erased by the erasing head 8.
The A/C head 10 records audio signals and control pulses.

Next, in the long-time recording mode, the tape is intermittently fed by the capstan 11, and video signals and control pulses are recorded on the tape section erased by the erasing head 8 in the same manner as in continuous feeding.

This intermittent recording enables long-term recording.

Problems to be Solved by the Invention However, at the beginning of tape winding, the area between the erasing head and the A/C head cannot be erased by the erasing head 8, and if recording is performed in that area for a long time, Since the tape is fed intermittently, the control pulses are overwritten, causing the problem that the servo is not activated during playback. In playback in 2-hour mode, the screen on which the servo is not applied is a portion corresponding to the length L, which is only a few seconds, so it can be said that it is not a big problem, but in playback in long-time recording mode, the portion of length L is The screen was distorted because the servo was not applied during this time, which was a problem peculiar to time-lapse VTRs.

In view of the above problems, the present invention automatically records a short distance at the beginning of tape winding in 2-hour (continuous) mode, thereby ensuring that control pulses are recorded, and the servo is completely maintained even during playback at the beginning of tape winding. The present invention provides a rotary head type recording/playback device as described above.

Means for Solving the Problems In order to solve the above problems, the present invention provides a switch for setting the time mode of recording and playback, a memory circuit for storing the setting value, and a switch for recording and playing back in the set time mode. The control circuit includes a tape start end detection circuit, a timer circuit that holds the detection signal for a certain period of time, and a time mode switching circuit that switches from the set time mode to the two-hour mode only when the timer circuit outputs. It is something.

Operation According to the present invention, with the above-described configuration, recording at the beginning of the tape is automatically set to the 2-hour mode, thereby preventing overwriting of control pulses, and making it possible to completely apply servo even during playback at the beginning of the tape.

Example Below, a time-lapse VTRK in an example of the present invention
This will be explained with reference to the drawings.

FIG. 1 is a block diagram of the present invention. In FIG. 1, numeral 1 denotes a time mode switch for setting the time mode during recording and playback, and is composed of several switches. 2 is a time mode memory circuit that holds the time mode set by the time mode switch 1;

3 is a tape start edge detection circuit, and 4 is a timer circuit that latches the tape start edge detection signal from the tape start edge detection circuit 3 and outputs a high level signal for several seconds when the recording mode is entered. 6 is a time mode switching circuit that outputs a 2-hour mode High signal only when the output of the timer circuit 4 is Hlqh, and outputs a High signal corresponding to the time mode set in the time mode memory circuit 2 at other times. .

6 is the operation switch, 5TOP, PLAY, REC
It is made up of several switches such as , and selects the operation mode of this VTR.

7 is the time mode set with time mode switch 1,
(a) loading motor, (b) cylinder motor, and (C) capstan motor so that the VTR operates in the operating mode selected by the operation switch 6.

(dl　!J-This is a circuit that controls the motor.

The operation of the time lag VTH configured as described above will be explained below.

First, when the 480H mode switch is pressed in the time mode switch 1, the 480H mode switch is activated by the time mode memory circuit 2.
0H is held and the time mode memory circuit 2 p480
An HHigh signal is output.

Here, if it is not the beginning of the tape, the output of the timer circuit 4 is Low, so the output of the time mode switching circuit 5 is the output of the time mode memory circuit 2 (in the above example, 480
(HHigh signal) is sent as is to the control circuit 7.

Then, when the REC switch of the operation switch 6 is pressed, the control circuit 7 controls the rotation motor and the cylinder motor 7.
Then, the capstan and reel motors are controlled, and the VTR enters the 480H recording mode.

Further, if it is the tape start end, a tape start end detection signal is latched by the tape start end detection circuit 3 into the timer circuit 4. Then, when the REC switch of the operation switch 6 is pressed,
The control circuit 7 controls the loading motor, cylinder motor, capstan motor, and reel motor, and controls the VTR.
is in recording mode. At the same time, the timer circuit 4 sends a high tape start signal to the time mode switching circuit 6 for several seconds. As a result, the time mode switching circuit 5 outputs the 2HHi signal instead of the 480HHigh signal.
The gh signal is sent to the control circuit 7, and the time mode water recording mode is set.

After a few seconds, the output of the timer circuit 4 becomes Low, and the output of the time mode switching circuit 6 becomes the output of the time mode memory circuit 2, which becomes the p480H High signal. Therefore, the VTR returns from the 2-hour mode to the 480H recording mode.

In other words, only the part of the tape from the erase head at the beginning of tape winding to the A/C head that is not erased in its entire width by the erase head is continuously recorded in 2-hour mode. It is now possible to completely apply the servo.

Effects of the Invention As described above, according to the present invention, by automatically recording in the 2-hour mode for only a few seconds at the beginning of tape winding, control pulses can be reliably recorded, and the servo is completely activated even during playback at the beginning of tape winding. This is an excellent method that can achieve the same effect without increasing the cost of a rotary erasing head or the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a rotary head type recording and reproducing apparatus. 1... Time mode switch, 2... Time mode memory circuit, 3... Tape start end detection circuit, 4... Timer circuit, 6... ...Time mode switching circuit, 6...Control circuit, 7...
...Erasing head, 8...Rotating head, 9...
...A/C head, 1o...capstan,
11...Video cassette tape.

Claims (1)

[Claims] It consists of a switch that sets the recording/playback time mode, a memory circuit that stores the setting value, an erasing head that erases the entire width of the tape during recording, a rotary head that records the video signal in the erasing section, and an audio signal and control pulse. It is equipped with an A/C head for recording and playback, a tape start edge detection circuit, a timer circuit that holds the detection signal while the tape runs from the erase head to the A/C head in a 2-hour mode, and the timer circuit. A rotary head type recording and reproducing device comprising a time mode switching circuit that switches from the set time mode to the two-hour mode only during output.