JPH041937B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to the structure of a video tape recorder for intermittent recording and playback that is suitable for a surveillance VTR connected to a security camera or the like.

[Prior art] Figure 1 shows the conventional helical scan method.
FIG. 2 is a perspective view showing a tape running system of a VTR;
The figure is also a plan view. Figure 3 shows the conventional
FIG. 2 is a diagram showing an example of a magnetic tape pattern recorded on a VTR.

In a conventional helical scan type VTR, the magnetic tape 20 wound around the supply reel 11 of the cassette 10 is transferred to the cassette 10 by guide rollers 31 and 32 on the entrance side and guide rollers 33 on the exit side.
drawn from. After the magnetic tape 20 comes into contact with the full-width erasing head 41 and the impedance roller 51, it is wound around the rotating cylinder 60. Further, the magnetic tape 20 is connected to the impedance roller 5.
2, the audio erasing head 42, and the audio/control head 43, and is then sandwiched between the pinch roller 71 and the capstan 72. The magnetic tape 20 is pinched and pressed between the pinch roller 71 and the capstan 72, and as the capstan 72 rotates, it becomes possible to run for recording and reproduction. It is wound up.

The rotating cylinder 60 is composed of a pair of an upper rotating cylinder 61 and a lower fixed cylinder 62, and a video head 63 built in the upper rotating cylinder 61 allows the image to be displayed as shown in FIG. The signals are on channels 1 and 2 of the magnetic tape 20.
It is recorded on video tracks 21 and 22 of. Further, the audio signals are recorded on the audio tracks 23 and 24 of channels 1 and 2 of the magnetic tape 20 by the audio recording section of the audio control head 43.

The full-width erase head 41 is for erasing all the video signals, audio signals, control signals, etc. that have been recorded on the magnetic tape 20, and the audio erase head 42 is for so-called post-recording. .

In order to accurately record or reproduce each signal on the magnetic tape 20 as shown in FIG.
It is necessary to bring the magnetic tape 20 pulled out from the cassette 10 into accurate contact with each head.

In order to run a magnetic tape at a constant speed for recording and reproduction in the VTR shown in FIG. 1, a pinch roller 71 and a capstan shaft 72 sandwich and press the magnetic tape, and the rotating capstan shaft 72 The magnetic tape is run at a constant speed. In this case, a flywheel (not shown) is usually attached to the lower part of the capstan shaft 72 in order to eliminate speed unevenness during tape running, and increases the rotational moment of inertia of the capstan shaft 72. It is configured as follows.

By the way, in the case of general continuous recording/playback VTRs, there is no problem with the above configuration. However, for example, VTRs whose main purpose is intermittent recording, such as crime prevention or surveillance VTRs (for example, In a VTR that continuously records one frame, the tape speed must be suddenly brought to normal speed from a stopped state, and then the recording operation must be abruptly stopped, and these operations are repeated frequently. Conventional VTRs such as those described above are extremely inadequate for such sudden movements due to the presence of flywheels, etc., and therefore cannot be used for intermittent recording or recording.
It was hoped that a VTR suitable for playback would appear.

[Summary of the Invention] The present invention provides a brake capable of contacting the flywheel and a solenoid for bringing the brake into contact or non-contact with the flywheel. The purpose of this invention is to provide a new VTR with excellent intermittent recording/playback characteristics and reliability by using a different capstan drive method.

[Embodiment of the Invention] FIG. 4 shows a schematic partially cutaway sectional view for explaining an embodiment of the invention, and FIG. 5 shows a plan view.

71 indicates a pinch roller, and the pinch roller 7
1 is pressed against the capstan shaft 72. The capstan shaft 72 is also used as a rotating shaft of a capstan motor 73 that rotationally drives the capstan shaft 72, and is configured in a so-called direct drive capstan type. Bearings 73a and 73b are provided above and below the motor 73 to reduce vibration and uneven rotation of the rotating shaft. A capstan flywheel 74 is attached to the other end of the capstan shaft 72, and the diameter and weight of the flywheel 74 are designed to have an appropriate moment of inertia.

In addition, 100 indicates a base chassis made of, for example, aluminum die-casting and made robustly,
Components such as a capstan motor 73 are fixed to the base chassis 100 by fixing means such as screws.

As a characteristic configuration of this embodiment, the fixing metal fittings 78
A solenoid 75 is provided via the solenoid 75. A movable shaft 75a of the solenoid 75 moves up and down as indicated by arrow A. A brake stay 76 is connected to the movable shaft 75a, and a brake pad 77 is attached to the other end of the brake stay 76. The brake pad 77 is made of felt or leather, for example, and exerts a braking effect when it comes into contact with the capstan flywheel 74. Brake stay 7
The center of 6 is supported by a fulcrum metal fitting 79, and the fulcrum metal fitting 79 is fixed to a fixing metal fitting 78. The brake stay 76 is supported by a fulcrum metal fitting 79 so as to be rotatable about a shaft 79a. Further, the fixing metal fitting 78 includes a pressing spring 8.
A brake pressure adjustment bolt 80 is attached that passes through the brake stay 76 through the brake stay 76 . Therefore, by rotating the bolt 80, the pressure contact force between the brake pad 77 of the brake stay 76 and the flywheel 74 can be adjusted.

In this embodiment, when no current flows through the solenoid 75, no suction force is applied to the solenoid 75, so the brake pad 77 of the brake stay 76 is attached to push the flywheel 74 by the force of the fulcrum metal fitting 79 and the pressing spring 81. Forced. This pressing force, that is, the brake pressure, is determined by the pressing force of the spring 81, and can be finely adjusted by rotating the bolt 80.

On the other hand, when current flows through the solenoid 75 and an attractive force is applied, the movable shaft 75a of the solenoid is moved upward, and force is transmitted using the fulcrum fitting 79 as a fulcrum, and the brake pad 77 is moved in the direction of arrow B. , away from the flywheel 74, and the brake is released.

Since the embodiment shown in FIGS. 4 and 5 has the above-described configuration, during intermittent recording/reproduction, the capstan shaft 72 is moved while the brake pad 77 of the brake is in contact with the flywheel 74. By driving the tape, it is possible to rapidly change the tape speed from a stopped state to a normal speed for recording, and to suddenly stop the tape. On the other hand, during normal continuous recording/playback, solenoid 7
By applying current to the brake pad 5 and separating the brake pad 77 from the flywheel 74, it is possible to perform continuous recording and playback with little speed unevenness due to the effect of the flywheel 74, similar to a normal VTR.

In the embodiment shown in FIGS. 4 and 5, the brake and brake pads 77 were in contact with the bottom surface of the flywheel 74, but it is possible to contact the brake pads with other surfaces such as the side surfaces of the flywheel 74. may be configured. In addition, in order to reduce the surface contact of the flywheel as much as possible and keep the brake pressure constant, we have made changes within the scope of the design, such as selecting the material and shape of the brake pads appropriately, and applying a coating to the contact surface of the flywheel. Needless to say, it can be modified arbitrarily.

[Effects of the Invention] As described above, according to the present invention, since the brake that can come into contact with the flywheel and the solenoid that brings the brake into contact with or out of contact with the flywheel are further provided, during intermittent recording and reproduction, , it is possible to perform stop-record-stop operations quickly with the brake in contact with the flywheel, and on the other hand, during continuous recording and playback, the brake is not in contact with the flywheel, making it stable and reliable. It is possible to perform continuous operation with excellent performance. Therefore, it is possible to realize a video tape recorder with excellent accuracy and reliability in both intermittent and continuous operations.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a tape running system of a conventional VTR. FIG. 2 is a plan view of the tape running system shown in FIG. 1. FIG. 3 is a diagram showing an example of a magnetic tape pattern recorded on the VTR shown in FIGS. 1 and 2. FIG. FIG. 4 is a schematic side sectional view of one embodiment of the invention, and FIG. 5 is a schematic plan view of the structure shown in FIG. 20...magnetic tape, 71...pinch roller,
72...capstan shaft, 73...capstan motor, 74...flywheel, 75...
... Solenoid, 76... Brake stay, 77...
...Brake pads. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A helical scan type video tape recorder capable of intermittent recording and playback, in which a magnetic tape is wound around a rotating cylinder having a video head, which is a carrier for running the magnetic tape at a constant speed. a capstan motor; a capstan shift rotated by the capstan motor; a pinch roller press-contacted to the capstan shift with a tape interposed therebetween; a flywheel fixed to the capstan shift; A video tape recorder comprising a brake capable of contacting a flywheel and a solenoid for bringing the brake into contact with or out of contact with the flywheel, wherein the intermittent recording/playback is performed while the brake is in contact with the flywheel. .