JPH0125157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording device, and more particularly to a rotating head type magnetic recording device using a magnetic tape.

Rotating head type magnetic recording device, e.g. helical
In a VTR, a tape pulled out from a cassette is helically attached to a rotating head drum, and the tape is run at a constant speed to form an inclined track on the tape.One track covers one field or one frame of a television signal. If information is already recorded on a portion of the tape in the cassette, it is necessary to locate the beginning of the unrecorded portion of the tape that follows.

Conventionally, various methods have been proposed for finding the beginning of a magnetic tape as described above, but one example is a method that uses signals recorded on a control track or audio track provided separately from a video track using helical scanning. There are methods to cue by detecting the cue, and methods to cue by providing a separate small head exclusively for cueing.

Of the conventional methods mentioned above, the former method requires the tape to be completely attached to the rotating drum before it can be cued, and the latter method requires a new head for cueing. It was necessary to provide a 100% sec- ond , which was disadvantageous for small-sized VTRs and the like.

In recent years, with the development of electronic technology, it has become common for ordinary households to take pictures using a combination of a VTR and a video camera, and by making these devices smaller and lighter, highly portable video systems have been created. An increasing number of video cameras constituting such portable video systems use optical viewfinders instead of electronic viewfinders, which are relatively large and consume a lot of power. When a video camera is equipped with an electronic viewfinder, the playback video output from the camera can be checked in the viewfinder even when the camera is used outdoors or in other places where there is no playback monitor television. However, with a video camera equipped only with an optical viewfinder, it is impossible to perform such cueing by video playback.

An object of the present invention is to provide a rotating head type magnetic recording apparatus such as the above-mentioned video system in which unrecorded portions can be detected relatively easily. If this is applied to a VTR, it will not only be possible to create a simple video system at a low cost, but it will also be effective in making the device smaller and lighter. The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a cassette VTR according to the present invention, showing a tape loading state. In the figure, 1 is a cassette containing magnetic tape;
A supply reel 2 and a take-up reel 3 are provided inside the cassette, and a tape 1' is disposed along an opening on one side of the cassette. Reference numerals 4 and 5 are loading pins for drawing out the tape, which move to the illustrated positions during tape loading. Reference numeral 6 denotes a sub-drawer arm for loading, and a pull-out pin 6a is implanted in one end surface of the sub-drawer arm 6. 7 is an impedance roller, 8 is a full-width erasing head, 9 is a control head and an audio head, and 10 is a pinch roller, which moves to the illustrated position during loading and pinches the tape between it and the capstan 11. Reference numeral 12 designates a rotating head drum, and a magnetic tape 1' is helically attached to the outer peripheral surface of the drum.

FIG. 1 shows the tape loading state of a parallel loading type VTR. When a cassette 1 is loaded into the VTR, the tape pull-out pins 4 and 5, the pull-out pin 6a of the sub pull-out arm, and the pinch roller 10 are connected to the cassette. They are located at the hole portions (FIG. 2), and are moved to the positions shown in FIG. 1 by the driving of the loading mechanism to load the tape onto the rotary head drum 12. In the illustrated state, normal recording and reproduction is performed by driving the drum motor and capstan motor.

FIG. 2 is a block diagram showing the tape cue state of the apparatus shown in FIG. 1. When the tape is stored in the cassette in the tape unloading state, by pressing the pushbutton switch 12', the sub-drawer arm 6 and the tape 1' are slightly pulled out.
The rotating drum 12 is wound by a predetermined angle α°. In this state, the other pull-out pins 4, 5 and the pinch roller 10 do not move from within the hole of the cassette and take the position shown in the second figure. By pressing the switch 12', the switch 13 is closed and the VTR circuit is switched to the reproduction mode. In this state, when a switch (not shown) is set to fast forward or rewind mode, and the tape is run by driving the reel stand, the part of the tape wrap α is played back, and it is checked whether or not a signal is recorded on the tape. Can be detected.

FIG. 3 is a block circuit diagram showing an embodiment of a signal detection circuit in a VTR as an embodiment of the present invention. In the figure, the signal obtained by the rotational phase detection head 113 of the rotary head is generated by a pulse generation circuit 109 with a duty cycle of 50%.
It becomes a 30Hz (frame frequency) square wave signal. This is shown in Figure 4a. At the rising and falling parts of this square wave signal, a monostable multivibrator 110
and 111 respectively, pulses as shown in FIGS. 4b and 4c are obtained at their outputs. When the flip-flop 112 is operated with these pulse signals, a signal as shown in FIG. 4d is obtained at its output. This becomes a gate signal that gates the reproduction output in a range corresponding to a predetermined angle α at which the rotating head contacts the tape. The output signal reproduced from the tape 100 by the rotary head 114 is passed through a preamplifier 101 and a low-pass filter 10.
104
After converting the frequency using a local oscillator 105 in the frequency transformation circuit of 105 to the color subcarrier frequency of a standard television signal, the signal is mixed with the reproduced luminance signal through a bandpass filter 106 to obtain a composite color video signal as its output. .

During the tape cue operation, switch 115 is turned on, and the gate signal from flip-flop 112 is applied to gate 107, which gates the color subcarrier component signal from 106. That is, the color subcarrier component signal reproduced from the range of a predetermined angle α° where the tape of the rotary head 114 comes into contact is extracted by the gate 107 and passed through the low-pass filter 108 to output its DC component. By lighting up a light emitting element (LED) or the like using this output signal to display the cue portion, it becomes easy to confirm the unrecorded portion and the recorded portion of the tape.

As described in detail in the embodiments above, by applying the device of the present invention to a VTR, even when there is no video display device or electronic viewfinder, for example, when shooting with a video camera outdoors, the cassette It is possible to locate the beginning of a tape by checking recorded and unrecorded parts of the tape. In the above-described embodiment, during the tape cue operation, the number of attached parts such as tape guides is small, and the frictional resistance caused by these parts can be made much smaller than during normal running, so that power consumption can be reduced.

According to the embodiment described above, during the cueing operation, the angle at which the magnetic tape contacts the rotating drum is small, but the low-frequency converted color subcarrier component obtained from this portion remains unchanged even if the azimuth changes by several degrees. It can be reproduced sufficiently, and it is sufficient to display the cue.

As described above, the rotating head type magnetic recording device according to the present invention can clearly detect the presence or absence of an information signal recorded on a tape using an extremely simple method, and is particularly useful for portable video systems.
This can be extremely effective when applied to VTRs and the like.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the state of tape loading in a rotating head type magnetic recording/reproducing device;
FIG. 4 is a schematic diagram showing a tape cue state according to the present invention in the apparatus shown in FIG. 1, FIG. 3 is a block circuit diagram showing an embodiment of the tape cue method according to the present invention, and FIG. It is a waveform diagram of each part in a circuit. 1... Cassette, 2... Supply reel, 3... Take-up reel, 1'... Tape, 4, 5... Loading pin, 6... Sub drawer arm, 7...
Impedance roller, 8...Full width erase head, 9...Control head, audio head, 1
0...pinch roller, 11...capstan,
12... Rotating head drum, 12'... Push button switch, 13... Switch, 100... Tape, 101... Said amplifier, 102... LP filter, 103... ACC, 104... Frequency converter, 105... ...Local oscillator, 106...BP filter, 107...Gate circuit, 108...L.
P. Filter, 109...Pulse generation circuit, 11
0,111...monostable multivibrator, 1
12...Flip-flop circuit, 113...Phase detection head, 114...Rotary head, 115...
Switch.

Claims (1)

[Claims] 1. A rotating head type magnetic recording device in which information signals are recorded by loading a magnetic tape onto a rotating head drum using a tape loading means, wherein the tape is loaded onto the rotating head drum in a predetermined angular range smaller than the loading time during recording. means for attaching across;
means for gating a reproduction signal of the rotary head when the rotary head is in the predetermined angular range with the tape being attached to the predetermined angular range; and a signal gated by the means. a rotating head type magnetic recording device, comprising: means for determining the recording state on the tape using the method;