JPS63131302A - Rotary head type magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a normal reproducing signal even with a slip ring or a brush worn or damaged by making a switching element conductive only when a head does not scan a tape so as to charge up a power smoothing capacitor. CONSTITUTION:Since a power switching pulse being an LO level is fed to a base resistor 10 during a period when the head does not scan a tape, a transistor (TR) 9 is conductive and the power smoothing capacitor 4 is charged up to a Vcc [V] being a power voltage momentarily. While the head scans the tape, since the power switching pulse goes to an HI level, the TR 9 is opened, a head amplifier 2 is operated by a power current loop formed in a rotary drum only and using the charged electric charge of the power smoothing capacitor 4 as the power to make the slip ring and brush independently of the reproduction. Thus, even with the slip ring and brush having some flaw, no noise appears at an output of the head amplifier 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a method of supplying power to an electronic circuit in a rotating head type magnetic recording/reproducing device having an electronic circuit within a rotating drum.

[Conventional technology]

A schematic configuration diagram of a conventional device of this type is shown in FIG. 5, and a circuit diagram is shown in FIG. 6.

In this figure, 2 H is a fixed drum, 1151 is a shaft supported by the fixed drum via a bearing 01, a
η is the tanabata that drives the shaft 1, and the rotor (17
A) is fixed on the seat P7 (15), and the stator (1
7B) is fixed to the fixed drum θ→. The haze is an end ring attached to the lower end of the shaft to prevent the shaft I]5) from falling off. 1J9) is a flange fixed to the middle part of the shaft, and the rotary drum is fixed to the flange;
) is a head mounted on the rotating drum, and is positioned on the outer peripheral surface of the rotating drum in order to correspond to a tape cover not shown. (2) is the head amplifier that increases the output from the RAD, and (3) is the rotary transformer connected to the head amplifier.
3A) and the 1st turn side (3B).

(11) is the power supply for the head amplifier, which is connected to the power line (2) of the head amplifier via the power supply slip ring (6) connected to the shaft 0, and the power brush (7) in sliding contact with the power supply slip ring (6). ing. Further, ■ is a grounding wire of the head amplifier, which is grounded via a grounding slip ring (6) and a grounding brush (8).

Furthermore, the ring source line is grounded through a power supply smoothing capacitor (4).

Next, the operation will be explained.

When the rotary drum rotates with respect to the fixed drum 0 with the shaft holder 0 as the center of rotation by driving the 7-9 drum, the he-rad (1) is interlinked with the magnetic flux from the magnetic tape (not shown), so it is regenerated. Voltage is generated.

This reproduction voltage is input to the head amplifier (2) and is
Amplified by 5QaB. The output voltage is determined by the magnetic coupling of the rotary transformer (3B) and (3A), and the fixed drum (
After the signal is transmitted to the third person), it is supplied to a reproduction cosa processing circuit, and a reproduction signal of video, audio, data, etc. is obtained.

At this time, the 9 sources of the head amplifier (2) are supplied from the power supply (11) through the power brush (7) and the power slip ring (5), and the ground slip ring (6) and the ground brush (8). grounded through.

[Problem that the invention seeks to solve]

The conventional rotary head m magnetic recording/reproducing device is as described above.
Therefore, power is always supplied to the electronic circuit regardless of whether or not the head is scanning the top and bottom of the tape.

With this method, if the slip link was damaged as shown in FIG. 7, noise as shown in FIG. 8 would occur in the head amplifier output. The causes of this include: ■ Fluctuations in power supply voltage due to scratches on the power supply slip link; ■ Fluctuations in ground potential due to scratches on the ground slip ring; ■ Sparks generated at the scratches become electromagnetic noise that jumps into the head assist input. To solve this problem, conventional methods have been taken such as increasing the power supply smoothing capacitor to strengthen the power supply filter effect, but this is only effective against It was not possible to completely remove the noise.

This invention was made to solve the above-mentioned problems, and even if the slip link or brush is worn or scratched, noise will not enter the head amplifier output, and a normal playback signal will be maintained. The object of the present invention is to obtain a rotary head type magnetic recording/reproducing device that provides the following.

[Means for solving problems]

The rotating head type magnetic recording/reproducing apparatus according to the present invention has a power supply smoothing capacitor in the rotating drum having a capacity large enough to supply power to the electronic circuit with a charged load while the head is scanning the tape, and , a switching element is provided between the electronic circuit and the power supply, which provides continuity only during the period when the head is not scanning the tape.

[Effect]

The opening/closing element in this invention is conductive only when the head is not scanning on the tape, acts as a reference and charges the power supply smoothing cosidenser, and is open during the period when the head is scanning on the tape, so the electronic circuit is Power is supplied by discharging the power supply smoothing capacitor, and since power supply current does not flow through the slip ring and brushes, noise caused by deterioration of the slip links and brushes can be removed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the description of this embodiment, the description of t' will be omitted as appropriate for parts that overlap with the description of FIGS. 5 and 6.

Figure 1 is a circuit diagram when PNP transistors are used as switching elements, where (1) is the head, (2) is the head amplifier,
(3) is a 0-tally transformer, (4) is a power smoothing capacitor, (5) is a power slip ring, (6) is a ground slip ring, (7) is a power brush, (8) is a ground brush, (9 ) are switching elements, transistors 1 and 1l.
ol is the base resistance of transistor 1 F9+, (III
f″i′Ft source vCC theal.

In addition, the base resistor is supplied with a power switching pulse (
Figure 2) is given.

Next, the operation will be explained using FIGS. 1 and 2. In FIG. 1, during a period when the head is not scanning the tape, a power switching pulse of 0 level is applied to the base resistor +101, so that transistor 1 (9) becomes conductive. In this case, since the ON resistance of the transistor is very small, the power supply smoothing capacitor (4) is instantly charged to the power supply voltage v4111 (v).

Next, while the head is scanning the tape, the z source switching pulse becomes Hl, so transistor 1 (9
) is in an open state, and the current flowing through the slip link and brush fc''T1 is cut off.Then, the head amplifier (2) uses the charged power of the power supply smoothing capacitor (4) as a power source, and the current flowing through the slip link and brush is cut off. Since the slip link and brushes have no relation to the playback operation at all, even if the slip links and brushes are slightly scratched, noise will still appear in the output of the amplifier (2). Ganaha.

In this case, the head amplifier (2) amplifies the minute signal of the reproduction voltage of the head (reproduction voltage), so the bias current only needs to be very small. If a capacitor of
ma e c ), the power supply voltage hardly changes and the head amplifier (2) can operate stably.

In the above embodiment, a case has been described in which the opening/closing element is provided on the fixed drum side, but it is expected that the same operation will occur even if the opening/closing element is provided in the rotating drum, so one embodiment will be described below.

Fig. 3 is a circuit diagram of a combination in which the switching element is provided in the rotating drum; the transistor 1 (9) and the base resistor 110) are mounted in the rotating drum, and the slit link (I2 ) Tozurashi (has one moment, sends a power switching pulse into the oral drum, and performs a switching operation similar to the above-mentioned example in the rotating drum).

In addition, in the above embodiment, switching elements such as transistors were used to perform the source switching, but semiconductor elements such as FPT, relays, etc. may also be used, and four
If the slip printer is divided into a conductive part and a non-conductive part on the circumference as shown in the figure, the slip ring can be used as an opening/closing element.

Furthermore, in the above embodiments, an Oka having a head amplifier as a Vi electronic circuit was explained, but in a case where it has only a recording amplifier, or a case where it has a head amplifier and a recording amplifier,
Alternatively, the same effect can be achieved even when there are other appositives.

〔Effect of the invention〕

As described above, according to the present invention, a power supply smoothing capacitor having a capacity large enough to supply power to the electronic circuit with a charged load while the head is scanning over the head is provided in the rotating drum, and the head Since we have installed a switching element between the electronic circuit and the power supply that is conductive only when the head is not scanning the tape, the power current flows through the slip link and the brush during the period when the head is scanning the tape. This has the effect of eliminating noise caused by deterioration of slip links and brushes.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a rotary head type magnetic recording/reproducing device according to one embodiment of the present invention, FIG. 2 is a signal waveform diagram of a power switching pulse in one embodiment, and FIG. 3 is another embodiment of the present invention. FIG. 4 is an external view of a slip ring in still another embodiment of the present invention. Fig. 5 is a schematic configuration diagram of a conventional rotary head type magnetic recording/reproducing device, Fig. 6 is a circuit diagram of the conventional example, Fig. 7 is an external view of a slip link for explaining problems in the conventional example, and Fig. 8 The figure is a signal waveform diagram for explaining the problems of the conventional example. [11 is a head, (2) is a head amplifier, (4) is a power supply smoothing capacitor, and (9) is a switching element. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (5)

[Claims] (1) In a rotating head type magnetic recording/reproducing device having an electronic circuit in a rotating drum, a power supply smoothing capacitor having a sufficiently large capacity to supply power to the electronic circuit with a charge while the head is scanning the tape. A rotary head type magnetic recording/reproducing device, characterized in that the rotary drum has a switching element between the electronic circuit and the power source, which is in a conductive state only when the head is not scanning the tape. Device. (2) The rotary head type magnetic recording/reproducing device according to claim 1, wherein power is supplied to the electronic circuit by a brush and a slip ring. (3) The rotary head type magnetic recording/reproducing device according to claim 2, wherein the opening/closing element is provided on the fixed drum side. (4) The rotary head type magnetic recording/reproducing device according to claim 2, wherein the opening/closing element is provided within a rotating drum. (5) Claim 2, wherein the slip ring has a conductive portion and a non-conductive portion on the circumference.
The rotary head type magnetic recording and reproducing device described in 1.