JPS642260Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a cleaning device for a rotating head in a VTR.

To explain the rotary head in a conventional VTR with reference to FIG. 1, the cylinder section 1 is equipped with a lower cylinder and an upper cylinder, and the head H extends from the slit between the lower cylinder and the upper cylinder. It is attached to the lower surface of the upper cylinder or to a rotary disk provided separately from both cylinders, with the tip part exposed, and rotates in the direction of the Y arrow. Tape T
is loaded (wrapped) around the cylinder part 1 when the VTR is set to operate, and runs at the required speed. The head H rotates in the direction of the Y arrow as described above while slidingly contacting the tape T. By the way, the rotational force of the rotating head H is affected by the frictional force caused by contact with the tape T, the viscosity of the air during high-speed rotation, or the viscosity caused by adhesion of abrasion particles and dust in the air to the sliding surface. It is transmitted to tape T. For this reason, there is a difference in tape tension between the front and rear in the direction of rotation of the head, as shown in the figure.
(on the right side), it loosens, and at the rear, it tends to tighten.
Under such a situation, the tape tension generated at the rear acts to remove the dust 2 from the tape running path, causing the dust 2 to fall or to be removed to the cylinder peripheral surface outside the running path. However, dust 2, etc., tends to accumulate on the front side where there is a tendency to loosen, and when the amount of accumulation increases, the running path of the tape T is deformed so as to bulge on the front side as shown in the figure, and the head H and tape T are separated. A gap is formed between them. This phenomenon has the problem of causing spacing gloss during recording and reproduction, which prevents signal input and output from being performed normally and deteriorates the image.

To deal with this, conventional attempts have been made to increase the back tension of the tape T to raise the front tension to the extent that dust 2 does not accumulate, but this also considerably increases the rear tension and accelerates head wear. However, this was not a good idea as it shortened the life of the head. Another method is to scrape off the accumulated dust 2 with a cotton swab impregnated with alcohol or the like, or to remove it by running a cleaning tape (wrapping tape) in one direction. However, the former cotton swab method can be applied to devices such as audio tape recorders that have a large, sturdy head and a space to insert the cotton swab, but in VTRs, the thickness of the tip of the head is several degrees.
The diameter of the cotton swab is about 100 μm, and it is installed in an exposed state and cannot be said to be strong.Furthermore, the space around the cylinder part of general VTRs is not wide, so this cotton swab method is recommended for cleaning VTRs. It was not suitable as a means. In addition, when using the latter type of cleaning tape, if it is a rotating head type cleaning tape, there will be a difference in tape tension between the front and rear sides in the direction of rotation of the head, as described above, so the cleaning effect on the front side will be insufficient. Therefore, it could not be said that it was suitable as a cleaning means for a rotating head.

This invention aims to solve these conventional problems.

This invention will be explained below based on the drawings. Second
Figures 4 to 4 are diagrams showing an embodiment of this invention.

First, to explain the configuration, an operation button _B0 for setting a cleaning mode is attached to the operation button block B for each mode on the VTR. Other operation buttons are conventional ones, such as B ₁ is the playback mode button, B ₂ is the recording mode button, B ₃ is the still image mode button, B ₄ is the slow image mode button, and B ₅ is the double speed image mode. It's a button. The operation signal output line _l1 of the operation button _B0 is connected to the rotary head control circuit U together with similar output lines from the other operation buttons _B1 to _B5 , and the output line of this control circuit U is connected to the rotary head motor. M (rotating head cylinder motor if the head is attached to the upper cylinder rotating type).

In addition to the known servo circuit SV and drive circuit D, the rotary head control circuit U includes, as shown in FIG.
This design is equipped with a sequencer (forward/reverse command signal generator) SEQ. As is well known, the sequencer SEQ is composed of a CMOS or TTL logic circuit or a microcomputer, and in the illustrated example, the play pulse e ₁ from the play key (not shown) in the VTR is input to the input side. input line _l2 ,
and an input line _l3 for a stop pulse _e2 from a stop key (not shown). Also, from the output side, there is an output line for the start/stop signal _e4 .
l ₄ and an output line l ₅ for the forward/reverse control signal e ₃ are derived, and both output lines l ₄ and l ₅ are connected to the drive circuit D. The sequencer SEQ is set to an operating state in which a forward/reverse control signal _e3 can be output by an operation signal from the cleaning mode setting operation button _B0 . Then, when the play pulse e ₁ is input, a forward/reverse control signal e ₃ for the forward rotation 3a and reverse rotation 3b of the motor M is output alternately at appropriate time intervals for the required time t before shifting to a steady running mode such as regeneration. do. Incidentally, when only the play key and the stop key are operated while the cleaning mode setting operation button _B0 is not operated, only the start/stop signal _e3 is input to the drive circuit D from its output line _l5 . At this time, only a constant running mode such as regeneration is performed without any cleaning operation. In addition, use the push switch as the operation button B ₀ for cleaning mode setting, and press the play pulse with the original push button.
A signal corresponding to e ₁ is sent to sequencer SEQ, and a signal corresponding to stop pulse e ₂ is sent at the next push-off, and tape loading and forward/reverse operations from sequencer BEQ can be performed by simply operating this operation button _B0 . It can also be configured to output the control signal _e3 and unload the tape.

Next, the operation will be explained with reference to FIG.

When the cleaning mode setting operation button _B0 is pressed and the play key is pressed from the stopped state (period a in Fig. 5), the rotary head H starts to rotate in the forward direction and at the same time the tape is applied to the cylinder section 1. Loading is performed (period b in the figure). After loading is completed, the take-up reel shaft starts rotating and the tape T starts running, and the tape guide post moves a required amount (a level amount indicated by reference numeral 4 in FIG. 5) to apply tension to the tape T. A forward/reverse control signal _e3 is output from the sequencer SEQ almost simultaneously with the start timing of the tape T running, and this control signal _e3 causes the motor M to operate as appropriate for the required time (period c in the figure) via the drive circuit D. Forward rotation F and reverse rotation R are repeated alternately at time intervals. At this time, since an appropriate tension is applied to the tape T, the head H rotates forward and backward while slidingly contacting the tape T under this tension, thereby removing dust 2, etc. attached to the sliding surface. Cleaned. After the cleaning mode has elapsed, the VTR directly shifts to a normal running mode such as playback (period indicated by d in the figure).

Next, FIG. 6 is a time chart for explaining the operation when the cleaning setting operation button B ₀ has a function of sending out signals corresponding to the play pulse e ₁ and the stop pulse e ₂ as described above. be.

At this time, when the operation button _B0 is pressed from the stopped state (period a in the figure), tape loading is performed first, and then the cleaning mode (period c in the figure) is entered. After cleaning for an appropriate amount of time, push off the operation button _B0 to turn the head H.
The forward and reverse rotations of 1 and 2 are stopped, and the series of cleaning operations is completed from unloading (period f in the figure) to stop (g in the figure). Incidentally, the tape loading state at this time may be the minimum winding angle necessary for the cleaning action.

In each of the above-mentioned embodiments, a case has been described in which cleaning is performed by rotating the head H in the normal running state of the tape T, but a known cleaning tape is applied to this invention, and the head H is cleaned while running the cleaning tape. H can also be reversed. The cleaning effect can be further enhanced by using a cleaning tape.

As detailed above, according to this invention, an operation button for setting the cleaning mode is attached to the VTR device, and the operational signal of this operation button is set to the operating state, and an appropriate start signal causes the rotating head motor to rotate in forward and reverse directions. A forward/reverse command signal generator that outputs a control signal is provided, and this forward/reverse command signal generator is connected to the drive circuit for driving the motor, allowing quick and easy operation.
It is possible to appropriately remove dust and the like from the sliding surface of the rotating head, and it is possible to provide a cleaning device that is extremely suitable for VTRs.

[Brief explanation of the drawing]

Fig. 1 is a plan view partially omitting the rotary head of a conventional VTR, Figs. 2 to 6 A, B,
C and D show an embodiment of the rotary head cleaning device according to this invention, FIG. 2 is a block diagram, and FIG. 3 is a more detailed diagram of the rotary head control circuit, etc. in the same block diagram. FIGS. 4A to 4D are time charts showing examples of input and output signals of the sequencer. FIGS. 5A to D are time charts for explaining the operation. FIGS. 6A to D
is a time chart for explaining the operation of another embodiment of this invention. 1: Cylinder part, B: Operation button block, B ₀ :
Cleaning mode setting operation button, D: Drive circuit, H: Head, M: Rotating head motor,
SEQ: Sequencer (forward/reverse command signal generator),
SV: servo circuit, T: tape, U: rotating head control circuit, _e1 : play pulse, e2: stop pulse, _e3 : forward/reverse control signal, _l5 : forward/reverse control _signal output line.

Claims (1)

[Scope of utility model registration request] A VTR device having a rotating head which rotates in sliding contact with a tape, a motor which drives and rotates said rotating head, and a drive circuit which controls and drives said motor,
a forward/reverse command signal generator which outputs a control signal for rotating the motor alternately forward and reverse at appropriate time intervals in response to an appropriate start signal and which is set to an operating state by an operation signal from the operation button, and which has an output line connected to the drive circuit.