JP2803363B2 - Sliding contact device - Google Patents

Description

The present invention relates to a video tape recorder (hereinafter, referred to as a VTR).
It is written. ) Relates to a sliding contact device for supplying a signal to the rotating drum.

2. Description of the Related Art In recent years, VTRs equipped with a sliding contact device are in the direction of digitization mainly for business use. Therefore, it is necessary to rotate the rotating drum at a high speed in order to record and reproduce a wideband digital signal. Then, the slip ring also rotates at a high speed, and the sliding speed between the brush and the slip ring also increases.

As a conventional sliding contact device, for example, Japanese Patent Laid-Open No. 1-1320
No. 75 discloses this.

 Hereinafter, a conventional sliding contact device will be described.

FIG. 5 is a perspective view of the conventional sliding contact device. In FIG. 5, reference numeral 1 denotes a holder, which is integrated with the slip rings 3a and 3b via an insulating member 2.
The holder 1 has a magnetic head (not shown) for recording or reproducing signals on a magnetic tape (not shown), and is provided coaxially with a rotating drum (not shown). The other of the brushes 4a, 4b, one of which is brought into sliding contact with the outer peripheral surfaces of the slip rings 3a, 3b with a small contact force, is fixed to the free end side of the plate-shaped shape memory alloys 7a, 7b. The fixed ends of the shape memory alloys 7 a and 7 b are fixed to the brush holder 5. The shape memory alloy 7a is connected to a DC power supply 9 via a switch 8, and the shape memory alloy 7b is grounded. The brush holder 5 is attached to a base 6 fixed to a chassis (not shown). Further, the shape memory alloys 7a and 7b are stored in a shape memory such that the free end side is displaced as shown by the broken line in FIG. 5 above the transformation temperature, and after the displacement, the brushes 4a and 4b move around the outer circumference of the slip rings 3a and 3b. It is configured to make sliding contact with the surface with a large contact force. In addition, the slip rings 3a and 3b are connected to a rotating drum (not shown).
Is connected to a recording / reproducing amplifier (not shown) built therein, and supplies DC power to the amplifier (not shown). As described above, it is necessary to provide a recording / reproducing amplifying circuit in the rotating drum in order to record / reproduce a wideband digital signal satisfactorily.

The operation of the sliding contact device configured as described above will be described below.

First, a rotating drum (not shown) starts rotating in response to a recording or reproduction command, and a slip ring 3 provided integrally therewith.
a and 3b also rotate clockwise at the same time. At the same time, the switch 8 is turned on to supply a current from the DC power supply 9 to a recording / reproducing amplifying circuit (not shown) built in the rotating drum (not shown), and the VTR enters a recording or reproducing state. . Further, when the shape memory alloys 7a and 7b are energized, the shape memory alloys 7a and 7b generate heat by themselves, and change the form to the state shown by the broken line in FIG. 5, and the contact force of the brushes 4a and 4b increases. Therefore, the contact state of the brushes 4a and 4b becomes good, and the occurrence of power supply noise due to poor contact can be prevented. When the magnetic tape (not shown) is simply fast-forwarded or rewound without performing recording or reproduction, or when the magnetic tape (not shown) stops running, the switch 8 is turned off to cut off the power supply. Shape memory alloy 7a,
By returning 7b to the state shown by the solid line in FIG. 5, the contact force between the brushes 4a and 4b is reduced. Therefore, the wear of the slip rings 3a, 3b and the brushes 4a, 4b can be reduced, and the life can be prolonged.

However, in the above-described conventional configuration, the period in which the contact force of the brushes 4a and 4b is reduced is fast-forward or rewinding.
Alternatively, the time is limited to when the running of the magnetic tape (not shown) is stopped, and the time relative to the total time including recording and reproduction is extremely small. Therefore, a sufficient effect cannot be expected for extending the life. Furthermore, most commercial VTRs are designed to reproduce signals even during fast-forward or rewind, and to monitor the recorded contents, in which case a reproduction amplifier circuit (not shown) is required. Therefore, the contact force between the brushes 4a and 4b must be increased. Further, even when the running of the magnetic tape (not shown) is stopped, the still image signal may be reproduced, and there is no period during which the contact force is set to be substantially small. The specific value of the large contact force is such that even if the brushes 4a, 4b and the slip rings 3a, 3b wear and the mechanical positions of the brushes 4a, 4b change, poor contact occurs even when the contact force decreases. The brushes 4a and 4b and the slip ring 3a need to have a sufficient contact force to prevent rotation, and to rotate a rotating drum (not shown) at a high speed in order to record and reproduce a wideband digital signal. , 3b wear quickly, shortening the service life and increasing maintenance costs.

The present invention solves the above-mentioned conventional problems, and provides a sliding contact device suitable for portable use which has a long service life even when a normal signal is constantly transmitted at a high speed and consumes low power. The purpose is to do.

Means for Solving the Problems In order to achieve this goal, the sliding contact device of the present invention comprises:
A rotating slip ring member, a brush member slidably in contact with the slip ring member, and a noise detecting means for intermittently operating at predetermined time intervals or every predetermined operation to detect noise due to poor contact between the slip ring member and the brush member A brush pressure varying means for varying a contact force of the brush member with an output of the noise detecting means; and a comparing means for comparing a variable amount of the brush pressure varying means with a predetermined value.

According to the present invention, the noise detecting means for detecting noise due to poor contact between the slip ring member and the brush member is intermittently operated by the above-described configuration, and the contact signal of the brush member is set to a necessary minimum by an output signal thereof. In this manner, the brush pressure variable means is controlled so as to reduce wear with less power consumption. In addition, abnormal wear is checked by comparing the variable amount of one cycle of the brush pressure variable means intermittently operated with a predetermined value, and if the wear is rapid, the intermittent operation is made dense to improve the reliability of performance.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a rotary drum device incorporating a sliding contact device according to a first embodiment of the present invention. In FIG. 1, reference numerals 10a, 10b, and 10c denote brushes, and slip rings 12a, 12b, and 12c each having a free end integrally formed of resin 11.
It is configured to make sliding contact. Also, brush 10a,
The other ends of 10b and 10c are fixed to a brush holder 13. The brush holder 13 is a brush pressure variable member 14 made of two general piezoelectric ceramics as an electro-mechanical conversion element.
Attached to the free end of the Further, the fixed end of the brush pressure variable member 14 is held by a brush mount 15. Further, the electrode of the brush pressure variable member 14 is connected to an element drive circuit 16, and signals from an element power supply 17 and a noise detection circuit 18 are input to the element drive circuit 16. The output of the element drive circuit 16 is connected to a life comparison circuit 19 in addition to the brush pressure variable member 14, and its output is connected to an alarm generation circuit 20 and an alarm 21 such as a buzzer or a lamp. Further, both ends of the noise detection resistor 23 connected in series between the brush 10a and the amplifier power supply 22 are connected to the noise detection circuit 18.

Here, more detailed configurations of the noise detection circuit 18, the element drive circuit 16, and the brush pressure variable member 14 and the relationship between them will be described. First, at the time of initial setting of the apparatus (at the time of manufacture or replacement of parts), the apparatus is set to the recording mode and noise caused by poor contact between the brushes 10a and 10b used for power supply and the slip rings 12a and 12b is eliminated. The detection is checked by the detection circuit 18, and the output of the element drive circuit 16 is initialized so as to reach the allowable noise limit amount e shown in FIG. After that,
The noise detection circuit 18 constantly checks the amount of noise due to poor contact, and if the noise exceeds the allowable noise limit e, increases the output of the element drive circuit 16 to increase the brush pressure variable member 14.
Is displaced in the direction of arrow d in FIG.
b, 10c increase the contact force, always allow noise limit e
(Minimum required contact force) is automatically set. The output of the element drive circuit 16 is always held, and is returned to the original position when the power of the apparatus is turned on again. Also, the slip rings 12a, 12
b and 12c are attached to the main shaft 24 via the brush holder 13, and the rotating drum 25 has a fixed magnetic head for recording and reproduction.
26 and 27 (two are arranged at 180 degrees division) and a recording and reproducing amplifier 28 connected to these magnetic heads (for excellent recording and reproduction of a wideband digital signal, the same as the conventional example of FIG. 5). It is necessary to provide a recording and reproducing amplifier circuit in the rotating drum.). The slip ring 12a is grounded to the power supply of the circuit board 29, 12b is grounded to the rotary unit (also serves as the ground of the circuit board 29), the brush 10a is connected to the noise detection resistor 23, and 10b is the main body of the apparatus. Grounded.
The brush 10c is connected to an amplifier switching circuit 30, and the slip ring 12c is connected to a circuit board 29. Then, the connection between the fixed magnetic heads 26 and 27 and the rotary transformers 32 and 33 to be described later and the amplifier 28 are switched between the recording side and the reproduction side. A rotating rotary transformer 32 is attached to a disk member 31 that holds the rotating drum 25, and is connected to a recording and reproducing amplifier. In addition, the fixed rotary transformer 33 opposed thereto is a fixed drum 34.
And connected to an external circuit. The disk member 31 is attached to the main shaft 24,
25 is rotatably held by ball bearings 35 and 36 so as to rotate coaxially with the fixed drum 34. A motor unit including a rotor magnet 37 and a stator coil 38 is incorporated below the main shaft 24.

The operation of the sliding contact device of the first embodiment configured as described above will be described below.

First, when the apparatus main body is set to the recording mode, a DC power is supplied to the circuit board 29 via the brush 10a and the slip ring 12a, and a signal from the amplifier switching circuit 30 is supplied to the rotary transformer 32 and the two fixed magnetic heads. 26 and 27 are connected to the recording side of the recording and reproducing amplifier 28. And
The recording signal flows to the two fixed magnetic heads 26 and 27, and at the same time, the current is also supplied to the stator coil 38 so that the rotating drum 25 starts rotating in the counterclockwise direction and is continuously connected to the running magnetic tape (not shown). Record the signal at In addition, according to the start command of the recording mode, the output value at the time of use immediately before the element drive circuit 16 is held is output, and the brushes 10a, 10b, 10c
Is brought into contact with the slip rings 12a, 12b, and 12c, and then the brush pressure variable member 14 is controlled so as to be constantly stabilized at the allowable noise limit amount e as shown in FIG. Then, the running of the magnetic tape is stopped by the stop command, the rotating drum 25 is also stopped, and the recording signals flowing to the two fixed magnetic heads 26 and 27 are also stopped. When the rotating drum 25 stops, the slip rings 12a, 12b, and 12c also stop, so that noise cannot be detected. Therefore, the output of the element drive circuit 16 is held at the value immediately before the stop command.

Further, when the apparatus body is set to the reproduction mode, the brush 10a and the slip ring 12a
And a signal from the amplifier switching circuit 30 connects the rotary transformer 32 and the two fixed magnetic heads 26 and 27 to the reproducing side of the recording and reproducing amplifier 28. Then, the two fixed magnetic heads 26 and 27 reproduce signals from a magnetic tape (not shown). In response to the start command of the reproduction mode, the operation starts from the output immediately before the element drive circuit 16 holds, and similarly to the recording operation, the brush pressure variable member 14 is controlled so as to be always stabilized at the allowable noise limit amount e shown in FIG. Control. Then, the output value of the element drive circuit 16 immediately before the stop command is held by the stop command, and all operations stop.

The rotary drum 25, the noise detection circuit 18, and the element drive circuit 16 are also used when reproducing a signal during fast forward and rewind, and when reproducing a still image signal when a magnetic tape (not shown) stops running. Operates in the same manner as described above.

The output of the element drive circuit 16 is a constant life comparison circuit.
Compared with the life values of the brushes 10a, 10b, 10c and the slip rings 12a, 12b, 12c, which have been input to 19 and set in advance by experiments, the alarm generation circuit 20 is activated when the life value is reached. Activate the alarm 21 such as a buzzer or lamp to notify that it is time to replace it.

According to the present embodiment, as described below, noise due to poor contact between the brushes 10a, 10b supplying power and the slip rings 12a, 12b is detected by the noise detection circuit 18, and the brushes 10a, 10b
The wear can be reduced by controlling the brush pressure variable means so that the contact force of b, 10c is always the minimum necessary, and the life of the brushes 10a, 10b, 10c and the slip rings 12a, 12b, 12c can be extended. Can be planned.

FIG. 4 is a block diagram showing a connection between a brush and a slip ring unit and a circuit of a sliding contact device according to a second embodiment of the present invention. In FIG. 4, 10a, 10
b and 10c are brushes. Reference numerals 12a, 12b, and 12c denote slip rings, which are integrated with a resin 11. Also brush
The other end of each of 10a, 10b, and 10c is fixed to a brush holder 13, and this brush holder 13 is attached to a free end of a brush pressure variable member 14 generally composed of two piezoelectric ceramics as an electro-mechanical conversion element. Installed. Further, the fixed end of the brush pressure variable member 14 is held by a brush mount 15.

The above configuration is the same as in FIG. The slip rings 12a, 12b, 12c are attached to a main shaft (not shown) via a brush holder 13, and are connected to a circuit board (not shown) having a recording / reproducing amplifier. Then, power is supplied to the recording / reproducing amplifier, and the connection between the recording / reproducing amplifier and the magnetic head (not shown) attached to the rotating drum is switched by a command of the amplifier switching circuit 51. Is the same as that of the first embodiment shown in FIG. 1, and a detailed description thereof will be omitted. The electrode of the brush pressure variable member 14 is connected to an element drive circuit 39, and signals from an element power supply 40 and a noise detection circuit 41 are input to the element drive circuit 39. The output of the element drive circuit 39 is also connected to a life comparison circuit 42 in addition to the brush pressure variable member 14, and the output of the life comparison circuit 42 outputs an alarm 44 such as a buzzer or a lamp via an alarm generation circuit 43. It is connected to the. Further, the output of the element drive circuit 39 is input to a one-cycle variable amount comparison circuit 50, and the variable amount from one cycle before is compared with the wear average value in one cycle. A signal for shortening the intermittent drive cycle is output to the drive circuit. The noise detection circuit 41 includes an output signal of an intermittent drive circuit 46 that operates according to a command from the system control 45, a power supply 47 and a brush.
Both ends of the noise detection resistor 48 connected in series between 10a are connected. Then, brushes 10a and 10b and slip ring 1
Intermittent drive circuit 46 reduces noise generated by poor contact between 2a and 12b.
It is configured to work from Also, the noise detection resistor
The switch 48 is configured to short-circuit both ends during a period other than the check period, and the power supply of the noise detection circuit 41 is turned off during the period other than the check period. Also, the command from the intermittent drive circuit 46 includes a life comparison circuit 42, an alarm generation circuit 43,
The power is also input to the alarm 44 and the power is
It is configured to be turned off. However, the life comparison circuit 4
The operation of the alarm generation circuit 43 and the alarm 44 is held when the service life of the alarm 2 is detected, and the alarm 44 is activated even during a period other than the check period.

The noise detection circuit 41, the element drive circuit 39, and the brush variable member 14 will be described in more detail. First, at the time of initial setting of the apparatus (at the time of manufacture or replacement of parts), the apparatus is set to the recording mode and the brushes 10a and 10b used for power supply are used.
The noise detection circuit 18 checks for noise due to poor contact between the motor and the slip rings 12a and 12b, and controls the element drive circuit 39 so that the first set value f is smaller than the allowable noise limit amount e shown in FIG. Initialize the output. Thereafter, the noise detection circuit 18 checks for noise due to poor contact at predetermined intervals according to a command from the intermittent drive circuit 46, and increases the output of the element drive circuit 39 if the second set value g is exceeded. Then, the contact force of the brushes 10a, 10b, 10c is increased to return to the set value f.
Here, the purpose of providing the second set value g is to ensure the safety in consideration of the variation of the noise increase that proceeds during the noise non-detection period.

The operation of the sliding contact device of the second embodiment configured as described above will be described below.

First, when the apparatus body is set to the recording mode, a DC power is supplied to a recording / reproducing amplifier (not shown) through the brush 10a and the slip ring 12a, and a signal from the amplifier switching circuit 51 is magnetically transmitted as in FIG. A head (not shown) is connected to the recording side of the recording / reproducing amplifier. Then, a rotating drum (not shown) starts rotating, and a signal is continuously recorded on a running magnetic tape (not shown). At the same time, the system control 45 starts the operation of the intermittent drive circuit 46, and the intermittent drive circuit 46
Every minute), the power is supplied to the noise detection circuit 41, the life comparison circuit 42, the alarm generation circuit 43, and the alarm 44, and the switch 49
To off so that noise can be detected. And
The amount of the noise signal is checked by the noise detection circuit 41, and the third
If the set value g is equal to or more than the set value g, the output of the element drive circuit 39 is increased to increase the contact force of the brushes 10a, 10b, and 10c, and the noise is reduced to the set value f. Stop the noise detection circuit 4 until the next operation.
1. The power supply to the life comparison circuit 42, the alarm generation circuit 43, and the alarm 44 is stopped, and the switch 49 is turned on to short-circuit, thereby saving power consumption.

However, if the amount of the noise signal is large and the relative variable amount of the brush pressure variable member 14 with respect to one cycle before is larger than a reference set as an average value worn out in one cycle, the intermittent drive circuit 46 A signal (for example, a 10-minute cycle) for shortening the intermittent drive cycle is output to check closely. That is, for example, use environment (temperature, humidity, dust)
To determine whether the service life is being shortened due to abnormal wear due to abnormalities in parts or parts (material, dimensions, roughness, rotational accuracy), or whether noise has increased due to the temporary incorporation of dust. If the check is in progress, the check is continuously performed with the check timing time shortened. If the noise amount is temporary and the noise amount is significantly lower than the set value f at the next check, the contact force of the brushes 10a, 10b, and 10c is reduced and the set value is reset to the set value f. Thereafter, a check is performed at a normal timing. Also, in the former case, when it recovers, it returns to the normal operation as in the latter case. With this configuration, abnormal wear can be immediately detected even during intermittent checks, and recording and reproduction signals are not damaged.

The output of the element drive circuit 39 is input to the life comparison circuit 42, and is compared with the life values of the brushes 10a, 10b, 10c and the slip rings 12a, 12b, 12c, which are obtained and set in advance by an experiment. The alarm generation circuit 43
To activate the alarm 44 such as a buzzer or lamp,
Notify that it is time to replace. Since this operation is held, the alarm 44 is continuously activated even during a period other than the check period, so that the alarm 44 can be reliably notified.

As described above, according to the present embodiment, noise due to poor contact between the brushes 10a, 10b supplying power and the slip rings 12a, 12b is intermittently detected by the noise detection circuit 41, and the brushes 10a, 10b, By controlling the brush pressure variable means so that the contact force of 10c is minimized, wear can be reduced with low power consumption. In addition, the variable amount of one cycle of the intermittently operated brush pressure variable means is compared with a predetermined value to check for abnormal wear, and when the wear is fast, the timing of the check (intermittent operation) is made dense. With this configuration, the performance of the recording and reproduction signals can be guaranteed even in the case of intermittent operation.

In the second embodiment, when the wear is fast, the timing of the check (intermittent operation) is shortened, but the check may be performed continuously. Further, the timing of the check (intermittent operation) may be limited to only when the power is turned on or when the tape cassette is inserted. In this case, the checking operation after the detection of abnormal wear may be performed during the operation of the apparatus.

As described above, the present invention provides a rotating slip ring member, a brush member that slides on the slip ring member, and a noise caused by poor contact between the slip ring member and the brush member that operates intermittently every predetermined time. , An intermittent operation is provided by a configuration provided with a noise detection unit for detecting the brush force, a brush pressure variable unit for varying the contact force of the brush member with this output, and a comparison unit for comparing the variable amount of the brush pressure variable unit with a predetermined value. It is possible to control the contact force of the brush to a necessary minimum by the output signal of the noise detecting means, and it is possible to reduce wear with small power consumption. Therefore, the service life of the brush and the slip ring can be extended, the maintenance cost can be reduced, and the use time of the portable type device can be prolonged due to low power consumption. In addition, by detecting abnormal wear that occurs suddenly and performing noise detection and control closely thereafter, the performance of recording and reproduction signals can be guaranteed even during intermittent operation, and the reliability of the device is improved. improves. In addition, since the life is determined and an alarm is issued, the reliability is further improved and a work error can be avoided, so that the work efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotary drum device incorporating a sliding contact device according to a first embodiment of the present invention, FIG. 2 is a plan view showing displacement of a brush according to the first embodiment of the present invention, and FIG.
FIG. 4 is a diagram showing the state of noise caused by poor contact between the brush and the slip ring according to the first and second embodiments of the present invention. FIG. 4 is a diagram showing the brush of the sliding contact device according to the second embodiment of the present invention.
FIG. 5 is a block diagram showing the connection between the slip ring unit and the circuit, and FIG. 5 is a perspective view of a conventional sliding contact device. 10a, 10b, 10c: brush, 12a, 12b, 12c: slip ring, 13: brush holder, 14: brush pressure variable member, 18
…… Noise detection circuit, 16 …… Element drive circuit, 22 ……
Amplifier circuit, 23 ... Noise detection resistor.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01R 39/00-39/64 H02K 13/00-13/14 G11B 5/00-5/024

Claims (1)

(57) [Claims] 1. A rotating slip ring member, a brush member slidably in contact with the slip ring member, a brush pressure variable means for varying a contact force of the brush member, intermittent at a predetermined time or at a predetermined operation. A sliding contact device that operates, includes noise detection means for detecting noise due to poor contact between a slip ring member and a brush member, and intermittently controls a brush pressure variable means with an output signal of the noise detection means.