JPS5975425A - Video tape recorder - Google Patents

Abstract

PURPOSE:To reduce the wear of a rotary erasing head for edition and video tape, by fitting the head in a rotary head drum together with electricity-mechanism converting element under a condition where the head can be displaced in the direction of drum diameter. CONSTITUTION:A rotary erase head 24 for edition is fitted in a rotary head disk (drum) 22 together with an electromechanical transducing element 23. In this case, the rotary erasing head 24 is fitted to the rotary head disk 22 in such a way that, when no electric charges are impressed, the head does not project from the cylinder surface, namely, the head tip is out of contact with the magnetic surface of a tape. On the other hand, a record reproducing head is also fitted to the rotary head disk 22 under conditions where its projected length is adjusted to a specified value. By fitting the rotary erasing head in the rotary head drum in such a way, the wear of the head and tape can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a rotating drum for a video tape recorder (hereinafter abbreviated as VTR). Specifically, in addition to recording and playback heads, VTRs have a rotating erasing head for effectively editing splices, inserts, etc., in which this rotating erasing head comes into contact with the magnetic surface of the tape. This is only used when editing, and is not used in other modes,
That is, the purpose is to prevent unnecessary M on the head and magnetic surface of the tape by keeping it in a non-contact state during normal recording and playback, and during tape fast forwarding and rewinding.

For the production of video soft tapes that require high image quality for companies, educational centers, video production, or video gathering (ENG) such as documentary programs and news programs for television broadcasting, professional video tapes and half-inch cassettes are used. Video or U-standard VTRs have traditionally been used.

One of the major features of the U-standard VTR is that it uses a rotating erasing head specifically for editing. 16
The advantage is that you can perform full-fledged editing (connections, inserts, etc.) without disturbing the focal point at all. Recently, the original rotating erasing head has been adopted not only in these commercial U-standard VTRs but also in general home VTRs (VHS system, Beta system, etc.).
Development of high-end machines with full-scale editing functions is underway.

Here, we will briefly explain editing using the connection method as an example.

Generally, when recording on a VTR, h[:
In order to erase all recorded signals, the magnetic tape exiting the cassette 4 passes through a full-width erase head 2, as shown in FIG. This is a fixed erasing head located near the entrance of the rotating drum 1, and an audio/control signal recording head 3 located near the exit of the drum. Therefore, by the time you press the 11 start button, the full width erase head is already located between the full width erase head and the rotating drum.

The magnetic tape portions shown in (c) to (iii) are not erased and are dented in the dome (1), leaving an unerased portion on the magnetic surface of the tape. Figure 2 shows this situation.
9 is Eirin Signal Recording Dobutsuku, which has been recorded for some time.
A portion 120 indicates the video signal track left unerased. Further, 7 is an arrow indicating the tape running direction, and 8 is an arrow indicating the portion erased by the full-width erase head. Also,
(2) () is an audio signal recording track, and 11 is a control signal recording track.

Therefore, when recording is started at the editing start point 14, a new video signal is recorded over the unerased track section J2 mentioned above, resulting in double recording of the video signal as shown in the dotted area in the figure. A part is formed. If this happens, during playback, both corners will deteriorate, such as color beats occurring in this part, making it impossible to edit with good image quality.

Similarly, the portions Q to ■ in FIG. 1 are left unerased for the audio signal, resulting in a double recording portion of the audio signal as shown in FIG. 2B. cormorant.

This led to the idea of a rotating erasing head system. As shown in FIG. 3, this erase head J9-a,
] 9-b is placed on the rotating head 17 in a position that precedes the recording/playback heads 18-a and 18-b in the rotational direction, and the height is different from the recording/playback head. It is designed to trace the same trajectory as the record/playback head. Therefore, as the drum rotates, the erasing head first takes the lead and accurately erases each track one by one, and then continues to erase i;+2 'j'.
i': The head records new video signals. This is C
It is a method of erasing → recording without any pressure or rationality. This method has the great advantage that since there are no two-channel audio signals and control signals recorded on the magnetic tape, these can be used independently and freely.

However, this method also has major drawbacks.

Even during normal recording and playback without IrJ1 editing, the co-rotating erasing head comes into contact with the tape magnetic surface, causing unnecessary wear on the head and tape. In recent years, tapes that require long H# recording have become extremely thin, and video heads have also become much smaller and thinner due to the miniaturization of VTRs. Therefore, unnecessary wear and tear on heads and tapes becomes a major hindrance to extending the lifespan of VTRs and video tapes. Also, U
In VTRs such as standard VTRs and Beta VTRs, where the tape is rewound and fast-forwarded while being wound around a rotating drum, wear and tear is extremely common.

The present invention eliminates these conventional drawbacks and provides a video head,
The purpose is to prevent unnecessary wear of the magnetic tape and contribute to extending the life of the VTR.

Specifically, during normal recording and playback without editing (including special playback such as slow motion and still playback), the rotating erasing head is prevented from protruding from the rotating head and is kept in a non-contact state with the tape. By constructing a structure in which the rotating head protrudes from the rotating RAD drum and performs its function by contacting the tape only when editing is performed, unnecessary wear and tear can be prevented. be.

Hereinafter, the present invention will be explained in detail according to Examples. FIG. 4 is a diagram showing an embodiment of the present invention (wiring is omitted).
kF, upper cylinder, 21 is lower cylinder, 22 is rotation 1゛r
, is the head disk. z3 is the applied electricity No. 48 (
For example, the piezoelectric element is an element that has a characteristic of being displaced depending on the magnitude of the 'tlτ pressure), and in this embodiment, a piezoelectric element is used. Reference numeral 24 denotes a rotation consumption head, which is attached integrally with the piezoelectric element C. Reference numerals 5 and 26 denote piezoelectric elements 23, which are electrodes formed on both sides of the element, and by applying a voltage to these electrodes, the piezoelectric element 23 can expand and contract in its length direction. In general, a piezoelectric element has the property of contracting when a voltage is applied in the same direction as its polarization direction, and expanding when a voltage is applied in the opposite direction. Further, its displacement (expansion/contraction) is proportional to the applied voltage.

Now, regarding the rotary erasing head attached to this piezoelectric element, when no voltage is applied (that is, the piezoelectric element has its natural length), it is in a state in which it does not protrude from the cylinder surface, that is, the head chip is on the tape magnetic surface. The rotating head disk is adjusted so that it does not come in contact with the rotating head disk. On the other hand, the protrusion amount of the recording/reproducing head (not shown) is set to the standard value 'r, L'.
J alignment and mounted on the rotating head disk. Therefore, during recording, playback, tape rewinding, and fast forwarding without editing, only the recording/playback heads operate in contact with the tape magnetic surface. Next, in the case of performing the first collection of the recorder, when the editing start switch is turned on, the electric currents ν25 and 26 are connected to the circuit system (not shown) via the switch 27. Pressure is applied. Also, the direction of this voltage (
The polarity) should be in the opposite direction to the polarization direction of the piezoelectric element (i.e., the direction in which the piezoelectric element extends), and its size should be large enough to make the protrusion length of the rotary erasing head from the cylinder surface the standard value. It is set to

Next, when the editing is completed and the application of the stain pressure is released, the piezoelectric element returns to its natural length and the rotary erasing head is again in a non-contact state with the tape magnetic surface. In this way, the rotating erasing head contacts the tape magnetic surface only during editing, allowing the VTR to effectively perform its editing function, and the rotating erasing head does not contact the tape magnetic surface except during editing. This prevents unnecessary wear and tear on the head and tape.

FIG. 5 shows a block diagram of the ii'j pressure supply path for realizing the present invention. 45 is the editing start switch, and the key is i.
+ indicates a collection end switch or a normal recording/playback, tape rewind, or fast forward switch. 40 is a rotating erase head, 37 is a piezoelectric element, 38 and 39 are electrodes, and 42 is this electrode? i is also a push button for supplying voltage from the pressure generator 43. As you can see from the figure, when editing is finished,
During recording, playback, rewinding, and fast forwarding, there is no difference of 1 degree between the pair of electric conductors, so there is no elongation of the piezoelectric element.
The rotating erase head is maintained in contact with the magnetic tape 4J. When the editing start switch is turned on, a potential difference is created between the electrodes, so the piezoelectric element extends in the direction of the arrow in the figure, and the rotating erase head moves. 1; Place the contacts on the air tape.

FIG. 6 LL is a block diagram showing another embodiment of the present invention. In this example, two sheets '1.' with different polarization directions are used. ; element 4t], 4'7, three electrodes 48 p 49 p
Bimorph 4'i'￥ )'i by 50! ? It is attached to the rotating head disk 52. During normal recording/advance sale, when the tape is not wound, during fast forwarding, or at the end of the Wi: 4th episode (i.e., when no voltage is applied to the electrodes), the rotating erasing head 5] is not connected to the magnetic tape 53. kept in contact. When the editing start switch 57 is turned on, a voltage is applied to the electrodes by the voltage generator 55 via the υ brush 54. At this time, since the polarization directions of the piezoelectric elements 46 and 47 are opposite (one expands and the other contracts)
, the bimorph piezoelectric element flexes along arrow 58 into a state as shown by the dotted line, and the rotating erase head contacts the magnetic tape and performs its function.

In the previous explanation, we have described the rotating erasing head as being brought into contact with the tape by applying a voltage opposite to the polarization direction of the piezoelectric element to the electrodes during the first concentration. By applying voltage to the electrodes when not editing (
In other words, it is beyond the scope of the present invention to have a configuration in which the rotating erasing head is kept out of contact with the magnetic tape (by contracting the piezoelectric element), and the voltage is released during editing to bring the head into contact with the tape. isn't it.

In addition, as a method for applying voltage to the electrodes attached to the piezoelectric element, we have discussed the method using a push-pull, but the method is not limited to the push-pull; for example, an electromagnetic coupling method using a rotary transformer, other magnetic coupling methods, etc. There is no change in the effect of the present invention even if this is used.

As described above, according to the present invention, wear of the head and tape can be reduced by adding only a few parts to the VTRVC in front of the conventional editing machine, and the effect is significant.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the rotating head drum and the positions of each head. FIG. 2 is a diagram illustrating a tape that has been spliced and cut using a full-width erasing head. FIG. 3 is a diagram showing a recording/reproducing head and a rotating erasing head attached to a rotating head dome. FIG. 4 is a sectional view of a rotating rad drum showing an embodiment of the present invention. FIG. 5 is a block diagram showing an embodiment of the present invention. FIG. M6 is a block diagram showing another embodiment of the present invention. 50. Supply reel 600 Take-up reel J5...Editing end point 16...Next recording start point 28...
・Rotating shaft 29...Ball bearing:! I)・PG coil 31 for 0 rotation phase detection—same PG
Magnets 32, 33, Q rotary transformer 34, preload blood spring 35, cylinder motor stator 36, rotor magnet, etc. Applicant: Suwa Seikosha Co., Ltd. No. 1 Figure 1XC1-7/Hayabusa diagram

Claims (2)

[Claims] (1) In a video tape recorder which has at least a rotating head dome, a rotating magnetic head for recording/reproducing, and a rotating erasing head for editing, and is capable of recording, playing, and editing signals, the rotating erasing head for editing is provided. The rotary erasing head for editing is mounted in a rotating rad drum together with an electro-mechanical transducer element, and is displaceable in the radial direction of the drum, so that the rotating erasing head for editing can be in contact with the magnetic surface of the magnetic tape or in a non-contact state. A videotape recorder characterized in that it has a selective construction. (2) Record G t+! ! When editing the i-image, the electro-mechanical conversion element brings the editing rotary erasing head into direct contact with the i-tap, and in other cases, when the non-touch 1. A video tape recorder according to claim 1, characterized in that the video tape recorder is maintained in the same condition.