JPH0437287Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a rotary head cleaning device.
In particular, the present invention relates to a rotary head cleaning device (hereinafter simply referred to as a "cleaning device" or a "cleaning device") for a long-term recording video tape recorder (hereinafter also referred to as a "VTR"). [Prior art and its problems] In recent years, in a rotating head drum device for a VTR, recording and reproduction are performed by attaching a magnetic tape to a rotating magnetic head and transmitting and receiving signals. 5A and 5B are a plan view and a side view, respectively, of such a conventional rotary head drum device;
2 is an upper drum (rotating drum), and 2 is a magnetic head which is fixed to the upper drum 1 and rotates together with it. 3 is a lower drum (fixed drum); 4 is a magnetic tape that is wound diagonally over a predetermined angle and attached to the lower drum 3 and the upper drum 1; Loading members 5 and 6 wind the magnetic tape 4 around both the upper and lower drums 1 and 3, and are each provided with an inclined pole 8 and a rotating pole 9. In the VTR rotary head drum device having such a configuration, the magnetic head 2 and the magnetic tape 4 are in contact within the range of the predetermined winding angle, and the upper drum 1
The lower edge of the side where the magnetic head 2 is fixed also comes into contact with the magnetic tape 4 due to insufficient air film generated by rotation, and the longer the usage time, the smaller the amount of magnetic powder on the magnetic tape 4. They may come loose and adhere to the lower edge of the magnetic head 2, the upper drum 1, or the notch for exposing the magnetic head, or even dust may adhere to the space between the magnetic tape 4 and the magnetic head 2. It becomes difficult to send and receive signals normally, making recording and playback impossible, and the precise running of the magnetic tape 4 is disturbed, resulting in an increase in wah and screen distortion. Put it away. If such development begins to occur, the magnetic head 2, upper and lower drums 1,
3 must be cleaned (hereinafter also referred to as "cleaning") with a cotton swab or the like soaked in a cleaning solution, but the cleaning is complicated and troublesome. Therefore, in order to make cleaning relatively easy, a cleaning tape cassette (not shown) containing a cleaning tape was developed, and this was also used to clean the tape by applying it to a VCR. After cleaning, the tape cassette (not shown) must be taken out of the VTR and replaced with a new one, and then re-installed. It has the disadvantage of being Therefore, a cleaning device for a rotary head drum was developed which is configured to automatically clean the rotary head drum without using a cleaning tape cassette. As shown in FIG. 6, both the upper and lower drums 1 and 3
A felt roller (cleaner) 12 is provided at a location other than the tape attachment portion opposite to the rotational axis of the magnetic head 2, and is supported at one end of the rotating member 11. Almost the center of the rotating member 11 is a cylinder 7
The cylinder 7 is rotatably supported by a holder 13.
It is further fixed to the lower drum 3 by a holder 13. Reference numeral 14 indicates a coil spring, and reference numeral 15 indicates a protrusion provided on the holder 13 and facing each other at a position above the widthwise center of the rotating member 11. One end of the coil spring 14 is connected to a pin 16 mounted on the holder 13, and the roller 12 is normally pulled in a direction away from the upper and lower drums 1 and 3. and,
Immediately after winding (loading) or unwinding the magnetic tape 4, the roller 12 is rotated by rotating the rotary member 11 clockwise for a certain period of time by a mechanism (not shown).
The cleaning work is performed by bringing the drums into contact with the upper and lower drums 1 and 3. However, in the cleaning device (mechanism) having such a configuration, the head is cleaned only when the magnetic tape 4 is wound or unloaded.
A VTR, such as a VTR, that continues recording after a long period of unused time (for example, several hundred hours or more) with the magnetic tape 4 loaded.
If a cleaning device is installed on the drum, dust will adhere to the drums 1, 3, etc., and since the recording operation will be performed with the dust adhered, it will gradually become difficult to record with a good S/N ratio, and the reproduced image will deteriorate as a result. There was a problem with this. [Means for solving the problem] The rotary head cleaning device of the present invention uses a solenoid as a means for generating a pressing force on the rotary drum (and rotary head) of the cleaner, and a signal for driving the solenoid. A selection circuit that detects whether the VTR main body is in long-time recording mode or is not recording and outputs an operation signal as a supply means, and a pair of magnetic heads is switched by the operation signal from this selection circuit. a counter that inputs and counts pulses; a pulse generation circuit that generates a solenoid drive signal when the counter counts a predetermined number of pulses;
The above problem is solved by providing at least a timer for setting the driving time of the solenoid. [Embodiment] An embodiment of the rotary head cleaning device of the present invention will be described with reference to FIG. 1 and subsequent figures. FIGS. 1A and 1B are plan views showing the rotary head cleaning device 10 of the present invention when it is not in operation and when it is in operation, respectively. In these figures, the same components as those of the conventional device shown in FIGS. are given the same reference numerals and detailed explanation thereof will be omitted. In Figure 1, 17 is a solenoid, 18 is a power lever, 1
9 is a cleaner arm. Since the power lever 18 is tensioned by a coil spring (tension spring) 14, the roller (cleaner) 12 is normally spaced apart from the drums 1 and 3, but the solenoid 17 is
When the drums 1 and 3 act, rotational force is applied in the counterclockwise direction as shown in FIG. FIG. 2 is a block diagram showing an example of a drive circuit 20 for causing the rotary head cleaning device 10 to perform a cleaning operation, that is, for activating the solenoid 17. In the figure, 21 is a first selection circuit, 22 is an adder, 23 is a counter, 24 is a second selection circuit, 2
5 is a first pulse generating circuit, 26 is a second pulse generating circuit, 27 is a reset circuit, 28 is a gate circuit, 29 is a timer, and 31 is an amplifier circuit that supplies an operating signal to the solenoid 17. Next, the operation of each part of the drive circuit 20 will be explained with reference to FIGS. 3 and 4. The first selection circuit 21 has four input terminals In ₁ to I _o 4.
have S and REC signals and MD ₀ to
Provided with MD ₂ signal. The S.REC signal is a signal indicating whether or not the VTR main body is in the REC MODE (recording mode), and MD ₀ to _{MD 2} are signals indicating the recording time mode. (Therefore, the number does not necessarily have to be three.) When each of these input signals is in the state shown in Table 1, the output level of the selection circuit 21 is L.
(LOW level), and the counter 23 becomes operational. Two signals are supplied to input terminal In ₅ , but
This signal indicates whether or not head 2 (the head of the second channel) of the magnetic heads in [Table] is in the recording state, and as shown in Figure 3A, H and L are regularly repeated, so the counter input is Terminal Q ₁ (see table 2)
The counter 23 uses this signal as the (CLOCK) signal (see B in the same figure).
When the CH2REC signal rises from L to H (High level), that is, when it changes from a recording state to a non-recording state, it is counted up (that is, 23 is a binary counter). Note that Q ₁ to _{Q 12} in Table 2 are counter 2.
3 output terminals (not shown). [Table] The selection circuit 24 selects, for example, 11, 1 of the counter 23.
When both 2nd digits become H (C, D and 2nd digit in the same figure)
(see table), the output level is H. The next stage pulse generation circuit 25 receives the input signal (i.e., the selection circuit 24
output level) rises from L to H, H→L→
A high pulse TP1 (see E in the same figure and D in FIG. 4) is output to the gate circuit 28. This output pulse is supplied to the counter 23 via a reset circuit (consisting of an inverter, etc.) 27 and an adder 22, and is used as a reset signal for the counter 23 (see F in the figure). When the above output pulse is supplied to the timer 29 via the gate circuit 28, the timer outputs a signal that becomes H for the cleaning operation time of the cleaner (roller) 12, and this output signal is amplified by 31 and sent to the solenoid 17. The cleaner 12 is caused to perform a cleaning operation by suctioning the cleaner 12. As described above, since the counter 23 counts up when changing from the recording state to the non-recording state, the output pulse is also generated at the same timing.
Therefore, the time when the timer reaches H is the next CLOCK.
If it is set within the time until PULSE arrives, the cleaning operation will always be performed when no recording is performed, even if the magnetic tape 4 is not attached or released. DM as shown in Figure 4 A supplied to input terminal In ₆
Since the CTL signal becomes H when the upper drum 1 rotates, it changes from L to H when the tape is attached, and changes from H to L when the tape is released. Therefore, if the pulse generation circuit 26 is configured to generate a pulse (see B and C in the same figure) at the time of this change, it is possible to perform the cleaning operation when the tape is attached and when the tape is released, as in the conventional device. (See figure E). That is, the timer 29 outputs a drive signal for a predetermined time t, as shown in FIG. 4F, to cause the solenoid 17 to perform a suction operation. It goes without saying that the upper drum 1 is rotating during this cleaning operation. In this way, in any case, the cleaning operation is designed to be performed at times other than when recording signals, so there is no fear that any load applied to the upper drum 1 will affect the image quality. [Effects] Since the rotary head cleaning device of the present invention is configured as described above, it is particularly effective when installed in, for example, a time-lapse type VCR, and exhibits the following features. It can be cleaned at predetermined time intervals (for example, every few hours) during long-term recording. A recording mode with a long non-recording period allows cleaning during non-recording periods. Since the cleaning work is configured to be performed when no recording is performed, there is no fear that it will adversely affect image quality. (Cleaning during recording will put a load on the upper drum 1, which will have a negative effect on image quality.) Since a solenoid (plunger) 17 is used and it is electrically operated by a timer 29, Cleaning time can be set arbitrarily.

[Brief explanation of drawings]

Figures 1A and B are plan views of the rotary head cleaning device of the present invention, Figure 2 is a block diagram of the drive circuit of the device of the present invention, and Figures 3 and 4 are signals for explaining the operation of each part of the drive circuit. A waveform chart (timing chart), FIGS. 5A and 5B are a plan view and a side view of a conventional rotary head drum device, and FIG. 6 is a perspective view of a conventional rotary head cleaning device. DESCRIPTION OF SYMBOLS 1... Upper drum, 2... Magnetic head, 3... Lower drum, 4... Magnetic tape, 10... Rotating head cleaning device, 12... Roller (cleaner),
14... Coil spring, 16... Pin, 17... Solenoid, 18... Power lever, 19... Cleaner arm, 20... Drive circuit, 21... First selection circuit, 22... Adder, 23... …counter,
24... Second selection circuit, 25... First pulse generation circuit, 26... Second pulse generation circuit, 27
...Reset circuit, 28...Gate circuit, 29...
...Timer, 31...Amplification circuit.

Claims (1)

[Scope of utility model registration request] A cleaner installed opposite to the rotation axis of a pair of magnetic heads attached to the rotating drum at a location other than the area where the magnetic tape is attached, and a support that supports the cleaner and transmits a pressing force to the rotating drum. A rotary head cleaning device for a VTR having a member, a solenoid is used as a means for generating the pressing force, and a solenoid is used as a means for supplying a signal for driving the solenoid, and the VTR main body is in a long-time recording mode; a selection circuit that detects that there is no recording and outputs an operation signal; a counter that inputs and counts switching pulses for the pair of magnetic heads based on the operation signal from the selection circuit; A rotary head cleaning device comprising at least a pulse generating circuit that generates the solenoid driving signal when a predetermined number of pulses is counted, and a timer that sets the driving time of the solenoid.