JPS6019053B2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary head type magnetic recording and reproducing apparatus (hereinafter referred to as VT) which records and reproduces signals by winding a magnetic tape at a predetermined angle around a head cinder containing a rotary head and causing the tape to run.
It is constructed so that a desired program can be reliably reproduced from the first copy prior to the start of reproduction of a recorded magnetic tape.

Conventionally, as shown in FIG. 1, during recording and playback, the video tape 2 is rotated by moving the movable posts 6 and 7 from the positions 6' and 7' shown in dotted lines to the positions shown in solid lines in FIG. A VTR has been considered in which the head cylinder 11 containing the head is wound around the head cylinder at a predetermined angle.

That is, during recording and playback, the video tape 2 passes through the fixed post 5 and the movable post 6 from the supply reel 3 to the head cylinder 1 from the tape entry point A to the contact point B, and after touching approximately half the circumference of the cylinder, the tape moves. It reaches the winding roll 4 via the post 7 and the fixed post 8. This tape running is called M loading because of its shape. Next, in the case of fast forwarding or rewinding, the moving posts 6 and 7 are set to positions 6' and 7' so that strong tension is not applied to the tape.
As shown by the dotted line in FIG. 1, the V-supply reel 3 reaches the take-up reel 4 via the fixed post 5, moving post 6', moving post 7', and fixed post 8.

Reference numeral 9 denotes an erasing head for erasing signals already recorded on the tape during recording.

FIG. 2 is an explanatory diagram showing the above operation in the state of recording signals on a tape.

The tape is assumed to move to the right when recording, playing, or fast forwarding, and to the left when rewinding. In addition, the first
In correspondence with the figure, for ease of understanding, the tape is shown from the back side (base side) rather than from the magnetic side. FIG. 2A shows the start of recording of certain recording information, and sequentially shows the progress of recording. In FIG. 2, the dense diagonal line down to the right indicates that another program has already been recorded on the tape (not a magnetic pattern). Now, when recording a new program on such a tape, the video head records a magnetic pattern at the part in contact with the cylinder as shown by the diagonal line C on the upper right, as shown in Figure A, and at the same time, the erasing head 9 Other recorded programs are erased starting from position 13. The opening diagram shows a state in which a completely erased portion is recorded, and normal recording is possible from this opening diagram state. Figure C shows a state in which recording is progressing further. When playing back a tape recorded in the above manner, complete cueing cannot be performed unless the tape is loaded in the state shown in Figure 2, which corresponds to a completely erased and definitely recorded record. do not have.

That is, it is necessary that the starting position 13 where the post-erasure recording is performed coincides with the hair starting point B. Since the tape was not reliably loaded at this position in the secondary system, it was impossible to locate the beginning completely. The present invention is for reliably performing such cueing using an index signal, and an embodiment thereof will be described below with reference to the drawings.

Reference numeral 10 in FIG. 1 is a program index signal writing head for recording index signals on the tape, and it is placed a distance d away from the erasing head 9 toward the cylinder side.

The index signal is recorded on the tape at the moment when recording of a program is started, and the state in which it is recorded on the control track of the tape is shown as 11 in FIG. Since the index signal is recorded in a superimposed manner with the normal signal, a method such as deep recording may be used to ensure reliability. The in. recorded on tape in this way. A program index signal detection head 12 in FIG. 1 is used to detect the index signal 11 during table feeding and rewinding and stop tape running.

During recording and reproduction, it is located at position 12, shown by the solid line, so as not to interfere with tape loading, but during fast forwarding and rewinding, it comes into contact with the tape and comes to position 12' to detect the index signal. Further, the head may be moved in a direction perpendicular to the plane of the paper while remaining at the position 12' so as not to interfere with loading. This head movement can be accomplished by using a cam or solenoid that is linked to the tape roving mechanism. In the present invention, the position of the index signal detection head 12' is limited as described below in order to accurately detect the face.
That is, the position of the index signal detection head 12' is limited so that the tape position 13, which is a distance d away from the position 12' toward the supply reel 3, is at the tape contact point B of the cylinder when M loading is completed. .

With this configuration, when the detection head 12' detects the index signal during fast forwarding or rewinding and the tape stops at that position, the tape position where the index signal 11 is recorded will be at the position of the detection head 12'. Match.
Therefore, the position 13 on the tape is located closer to the supply reel 3 by a distance d than the position of the detection head 12'. Therefore, if the above conditions are satisfied and the tape is M-loaded from this state, position 13 on the tape will match the tape contact point B of the cylinder, and if playback is performed from there, complete exposure will be possible. An example in which the position of the detection head is limited to the above conditions will be described below. First, in FIG. 1, in the process of M-loading the tape, the take-up roll 4 is braked by the brake means, and only the brake of the supply IJ-rule 3 is released, allowing the tape to move freely as the posts 6' and 7' move. be supplied. Furthermore, in FIG. 1, if the value obtained by adding d to the distance 8-7'-6'-12' in the tape path is equal to the distance 8-7-B in the tape path, the above condition is satisfied. do. In the embodiments described above, the erasing head 9 and the program index signal writing head 10 are each independent, but an embodiment in which a single head performs both functions will be described below.

Normally, it operates as an erase head and applies index signal current instead of erase current only when an index signal is to be recorded. In this case, while the index signal is being written, it is not erased, but if the index signal is recorded deep enough and strongly, no malfunction will occur during detection. Needless to say, when the erasing head is used as an index signal writing head, the index signal is written over the entire width of the tape. Note that in this case, the distance d is zero. Next, an embodiment will be described in which the present invention is applied to automatic recording using a timer.

A certain amount of time is required as the tape runs from the state where the green screen starts, that is, the state shown in FIG. 2A, to the state where the video signal is completely recorded, that is, the state shown in FIG. Conversely, in order to mirror a predetermined program, one must go back this amount of time and start mirroring. That is,
The timer causes the key image to start this amount of time before the set time. In the above explanation, for ease of understanding, it is assumed that the rotation of the video head, the start and stop of tape running, etc. are all performed instantaneously without any time delay. Changing the conditions is a design change and does not go beyond the scope of the present invention.

One way to correct the deviation that actually occurs is to control the degree of braking applied to both reels during loading. Finally, a specific example of the index signal will be explained using FIG. 3. FIG. 3 is an example of a detailed diagram of the index signal 11 in FIG. 2, which is a barcode-shaped index signal with a binary signal recording frequency of L and fo. By recording different barcode codes for each program, it becomes possible to specify the code and cue a particular program. In FIG. 3, the bar code has been devised so that detection can be performed correctly regardless of the tape running direction. That is, it is symmetrical with respect to the tape running direction. If the code shown in the figure is taken out in fast forward mode, it will be 100001, and if it is taken out in rewind mode, it will be 100001, and the same code will be generated regardless of the tape running direction. This is because the 3-bit codes are arranged vertically in reverse code order. In this example, since it is 3 bits, eight types of programs can be distinguished. Furthermore, various recording methods can be used, such as frequency modulation as in the example, amplitude modulation, and pulse modulation. As described above, according to the present invention, it is possible to select a specific program and reliably reproduce it with its face exposed, making the VTR extremely easy to use.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a tape running path according to an embodiment of the present invention, FIG. 2 is a diagram showing a signal recording state on the tape, and FIG. 3 is a diagram showing an example of an index signal. 1. Head Schilling, 2. M videotape, 3.
...Supply reel, 6,7...Movement post, 9...Erase head, 10...Index signal writing head, 12...Index signal reproduction Head, A... Tape girl enters, B...
・Tape bale exit point. Figure 3 Figure 1 Figure 2

Claims (1)

[Claims] 1. During recording and reproduction, the magnetic tape is in a first state where it is wound around a head cylinder containing a rotating head at a predetermined angle, and when rewinding and fast forwarding the tape, the magnetic tape is moved from the first state to the first state. In a magnetic recording and reproducing apparatus, the magnetic tape running path is changed by a moving post so that the magnetic tape is moved in a direction away from the head cylinder in a second state, and an index signal is recorded on the magnetic tape during recording. A signal head is provided on the tape entry point side of the head cylinder by a distance d from an erasing head for erasing recorded signals on the magnetic tape, and an index signal for reproducing an index signal from the magnetic tape in the second state. the first head.
A magnetic recording/reproducing apparatus characterized in that the magnetic recording/reproducing apparatus is provided at a distance d on the take-up reel side from a point on the magnetic tape in the second state corresponding to a tape contact point of the head cylinder in the state. 2. The magnetic recording/reproducing apparatus according to claim 1, wherein the erasing head is also used as an index signal recording head. 3. The magnetic recording and reproducing apparatus according to claim 1, wherein the index signals recorded on the tape are symmetrical in the tape running direction.