JPH0792887B2 - Rotating head type recording / reproducing device - Google Patents

Description

The present invention relates to a rotary head type recording / reproducing apparatus such as a VTR (video tape recorder), a DAT (digital audio tape recorder) and the like.

[Prior Art] In order to improve the SN ratio (signal noise ratio) at the time of reproduction, it is known to incorporate a head amplifier in the rotary drum and supply the drive voltage of this head amplifier through a slip ring. It is also conceivable to supply the drive voltage of the head amplifier via a rotary transformer dedicated to the power supply and a rectifier circuit.

[Problems to be Solved by the Invention] By the way, when the former slip ring is used, since the slip ring has to be attached to the rotary drum and a brush needs to be attached around the drum, the size of the drum becomes large and the VTR is extended. The whole becomes bigger. Also,
When using the latter rotary transformer dedicated to power supply,
Since the rotary transformer dedicated to the power supply is provided, not only the size of the apparatus becomes large, but also the AC power supply adversely affects the recording and reproducing circuit.

Therefore, an object of the present invention is to provide a rotary head type recording / reproducing apparatus which can easily obtain a driving voltage for a head amplifier in a rotary drum.

[Means for Solving the Problems] The present invention for achieving the above object includes a rotary drum, a recording / reproducing head attached to the rotary drum, a rotary side winding and a fixed side winding electromagnetically coupled to each other. A rotary transformer for both recording and reproduction, a recording signal processing circuit, a reproduction signal processing circuit, and the recording signal processing circuit is connected to the fixed side winding during recording, and the reproduction signal processing circuit is connected to the fixed side winding during reproduction. A recording / reproducing switching circuit connected to a wire, a recording signal transmission circuit provided on the rotating drum side for connecting the rotating side winding to the recording / reproducing head at the time of recording, and the recording at the time of reproducing including an amplifier. A reproduction signal transmission circuit provided on the rotating drum side for transmitting the output of the reproducing head to the rotating side winding, and a reproducing signal transmission circuit which is always connected to the rotating side winding and provided on the rotating drum side. And a rechargeable power source that is always connected to the rectifying circuit and that is provided on the rotary drum side and that is connected to the power source terminal of the amplifier of the reproduction signal transmission circuit. A rotary head type recording / reproducing, wherein the recording signal supplied from the recording signal processing circuit to the recording signal transmission circuit is rectified by the rectification circuit to charge the rechargeable power source. It is related to the device.

A recording head and a reproducing head may be provided instead of the recording / reproducing head.

According to the invention of each claim, since the rechargeable power source (for example, the battery and the capacitor) is charged by using the recording signal without using the special charging power source device, the rotating drum side The power for driving the amplifier can be obtained with a small and low cost device.

[First Embodiment] Next, referring to FIG. 1, a first embodiment of the present invention will be described.
Explain the VTR.

The basic structure of this VTR is the same as that of a VHS type or Betamax type small VTR.
It has a lower cylinder or fixed drum 2. Rotating drum 1
The first and second heads 3 and 4 composed of recording / reproducing magnetic heads arranged at 180 ° intervals are attached to the. The first and second heads 3 and 4 are rotationally driven together with the rotary drum 1 by a motor (not shown). A magnetic tape (not shown) runs along the rotating drum 1 on which an oblique scanning track is created.

The recording signal processing circuit 6 connected to the recording input terminal 5 is
Including a modulation circuit, for example NTSC composite video signal FM
Modulate and output. The reproduction signal processing circuit 7 FM demodulates the reproduced signal and outputs a composite video signal to the output terminal 8. The recording signal processing circuit 6 and the reproduction signal processing circuit 7 include a recording / reproduction switching circuit 9 and a first and second rotary transformer 1.
0, 11 and the first and second rotary drum internal signal processing circuit 1
It is connected to the first and second heads 3 and 4 via 2 and 13.

The first and second rotary transformers 10 and 11 are known ones, and the fixed side winding 10 provided on the fixed drum 2 side.
a, 11a and the rotating side winding 10 provided on the rotating drum 1 side
b, 11b, fixed side windings 10a, 11a and rotating side windings 10b, 1
1b are electromagnetically coupled to each other.

Since the first and second in-rotating-drum signal processing circuits 12 and 13 have the same configuration, only one of them is shown in detail and the other is shown as a block. The signal processing circuit 12 in the rotating drum is
A recording signal transmission circuit and a reproduction signal transmission circuit are provided between one terminal 14 of the rotary side winding 10b of the rotary transformer 10 and one terminal 15 of the first head 3. The rotating side winding 10
The other terminal 16 of b is connected to the ground, and the other terminal 17 of the head 3 is also connected to the ground.

The recording signal transmission circuit comprises a first transistor 18 as a switch connected between the winding terminal 14 and the head terminal 15. In the reproduction signal transmission circuit, one input terminal is connected to one head terminal 15, the other input terminal is connected to the other head terminal 17, and the output terminal is connected to the winding terminal 14 (operational amplifier (differential Head amplifier 19 composed of an amplifier).

Reference numeral 20 is a transistor control circuit for controlling the transistor 18 to be turned on at the time of recording and to turn off the transistor 18 at the time of reproducing, and is composed of two capacitors 21 and 22 and two diodes 23 and 24. Note that one end of the capacitor 21 is connected to the winding terminal 14, a diode 23 is connected in the reverse bias direction between the other end and the ground, and the other end of the capacitor 21 is connected to the transistor 18 via a diode 24. Connected to the base, capacitor 22 is connected between the base of transistor 18 and ground.

Reference numeral 25 is an amplifier control circuit for supplying a drive voltage to the head amplifier 19 at the time of reproduction and cutting off the supply of the drive voltage at the time of recording, and includes a second transistor 26, a diode 27, a capacitor 28, and a resistor 29. Become. The second transistor 26 is connected between one terminal 31 of the storage battery 30 provided according to the present invention and the power supply terminal 32 of the head amplifier 19, and the diode 27 is connected between the winding terminal 14 and the base of the transistor 26. The capacitor 28 and the resistor 29 are connected between the base of the transistor 26 and the ground.

33 is a half-wave rectifier circuit provided according to the present invention,
It comprises a rectifying diode 34 connected between the winding terminal 14 and one terminal 31 of the storage battery 30, and a smoothing capacitor 35 connected between the cathode of the diode 34 and the ground. The storage battery 30 has one terminal 31 connected to the power supply terminal 32 of the head amplifier 19 through the transistor 26 and the other terminal 36 connected to the ground in order to function as the power supply of the head amplifier 19. There is.

The operation will be described below.

When the VTR is set to the recording mode, F of the recording signal processing circuit 6
The M modulation circuit operates and a recording signal composed of a frequency signal is transmitted to the rotary drum 1 side via the rotary transformer 10. The recording signal of the rotary winding 10b of the rotary transformer 10 is sent to the head 3 via the transistor 18, converted into a DC voltage by the rectifying circuit 33 provided in a branched manner, and sent to the storage battery 30. Since the storage battery 30 has a relatively small capacity, this charging can be achieved using the recording signal. In this recording mode, the voltage of the rotary transformer 10 is clamped by the clamp circuit composed of the capacitor 21 and the diode 23, which charges the capacitor 22 through the diode 24, and the positive peak voltage of the recording signal becomes 2 Double DC voltage is obtained. As a result, the transistor 18 is turned on in the saturation region, and the recording signal is transmitted to the head 3. Further, in the recording mode, the recording signal is rectified by the diode 27 in the amplifier control circuit 25, the capacitor 28 is charged, the transistor 26 is turned off, and the head amplifier 19 is in a non-driving state.

Since the supply of the recording signal is stopped in the reproduction mode, the charging of the capacitor 28 in the amplifier control circuit 25 is also stopped,
The electric charge of the capacitor 28 is discharged through the resistor 29, and the base potential of the transistor 26 becomes the ground. As a result, the transistor 26 is turned on, the head amplifier 19 is driven by the storage battery 30, and the output obtained from the head 3 is amplified and sent to the rotary transformer 10. In the reproduction mode, the charge of the capacitor 22 flows to the ground through the base / emitter of the transistor 18 and the rotary winding 10b of the rotary transformer, and the transistor 18 is turned off within a short time. At this time, a reproduction output is generated from the head amplifier 19, but since it is about 1 mV, the diode 24 is kept in the off state and the capacitor 22 is not charged.

As described above, according to this embodiment, the power supply voltage of the head amplifier 19 in the rotary drum 1 can be supplied based on the storage battery 30 charged with the recording signal. Therefore, it is possible to improve the SN ratio while suppressing an increase in size and cost.

[Second Embodiment] Next, a VTR according to the second embodiment shown in FIG. 2 will be described. However, in FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. This VTR has a check signal generation circuit 40 for checking the necessity of charging the storage battery 30, a head 41 for giving this signal to the heads 3 and 4, and a check circuit connected to the reproduction output terminal 8. 42 and a microcomputer 43 for controlling the check. The magnetic tape 44, which is omitted in FIG. 1, is pulled out from the cassette 45 and wound around the rotary drum 1 in the form of Ω. A pair of reels 46 and 47 of the cassette 45 is rotated by a reel motor 48. In addition, a pinch roller, a capstan, etc. are arranged as a tape running device on the running path of the magnetic tape 44. The plunger solenoid 49 controls the winding of the magnetic tape 44 around the rotary drum 1.

In this device, when the power is turned on or a battery check command is given to the microcomputer 43, the microcomputer 43 sets the check reproduction mode. In the check reproduction mode, the magnetic tape 44 is separated from the rotary drum 1. Microcomputer 43
When the check signal generation circuit 40 is controlled by, a check signal composed of a frequency signal is generated from this and the head 41
An alternating magnetic field for checking is generated from. Since the head 41 is arranged to face the passages of the recording / reproducing heads 3 and 4, the check signal is detected and the rotary drum side signal processing circuits 12 and 13 are detected.
A reproduction signal processing circuit 7 for reproducing a reproduction signal outside the rotating drum via
Send to.

The check circuit 42 includes an integration circuit that integrates the reproduction output and a comparator that compares the output of the integration circuit with a reference voltage to detect the presence or absence of a reproduction signal. If the storage battery 30 supplies a predetermined voltage to the head amplifiers of the rotary drum side signal processing circuits 12 and 13, the level of the reproduction output voltage obtained at the reproduction output terminal 8 becomes equal to or higher than the reference level, and the check circuit 42 The microcomputer 43 is notified of a signal indicating that the storage battery 30 is charged. As a result, the microcomputer 43 immediately releases the check reproduction mode and sets the normal recording or reproduction mode.

On the other hand, when the check circuit 42 detects that the reproduction signal of the reference level or higher cannot be obtained, the check signal is notified to the microcomputer 43 and sent to the battery status indicator.
If the reproduction output is below the reference level, it means that the storage battery
Since it means that the voltage of 30 is low,
Reference numeral 43 sets a recording mode for charging, applies a recording signal (FM wave) to the in-rotating-drum signal processing circuits 12 and 13, and charges the storage battery 30. When a normal recording command is generated during the charging recording mode, the charging recording mode is released, the recording mode is shifted to the normal recording mode, and the storage battery 30 is charged in the normal recording mode. When a reproduction command is issued, the setting of the reproduction mode is suspended until the charging recording mode ends, and the reproduction is started after the charging recording mode ends for a predetermined time.

[Modification] The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example.

(1) As shown in FIG. 3, a pair of recording magnetic heads 3
a, 4a, and a pair of reproducing magnetic heads 3b, 4b arranged so as to have an angular difference of approximately 90 degrees with respect to them, respectively, the rotary drum side recording signal transmission circuits 12a, 13a and the rotary drum side. The present invention can also be applied to the case where the reproduction signal transmission circuits 12b and 13b are provided and these are connected to the recording circuit and the reproduction circuit outside the rotary drum via the rotary transformers 51, 52, 53 and 54. . In this case, the voltage of the storage battery 30 charged based on the recording signal supplied to the recording heads 3a and 4a is applied to the reproduction signal transmission circuits 12b and 13b. In FIG. 3, the heads 3a and 4b can be replaced with recording / playback heads, and the recording signal transmission circuits 12a and 13a can be replaced with recording and playback signal processing circuits.

(2) The storage battery 30 can be replaced with a capacitor, and the capacitor can be used as a chargeable power source.

(3) The frequency of the check signal sent from the check signal generation circuit 40 is changed in several steps, and the charge state of the storage battery 30 is judged not only by the change in the voltage level of the reproduction output but also by the change in the frequency characteristic. May be. At this time, the check circuit 42 incorporates a bandpass filter.

(4) The checking signal generator 40 shown in FIG. 2 can be replaced with an erasing signal generator.

(5) The present invention can be applied to DAT.

(6) The transistor 18 can be replaced with another signal transmission element, signal transmission circuit, or switch element.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a VTR of a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a VTR of a second embodiment of the present invention, and FIG. 3 is a rotary drum of a VTR of a modified example. It is a block diagram showing a head. 1 ... Rotary drum, 3 ... first head, 4 ... second head, 6 ... recording signal processing circuit, 7 ... reproduction signal processing circuit, 10, 11 ... rotary transformer, 19 ... head Amplifier, 30 ... Storage battery, 33 ... Rectifier circuit.

Claims (2)

[Claims] 1. A rotary drum having a rotary drum, a recording / reproducing head mounted on the rotary drum, a rotary winding and a fixed winding electromagnetically coupled to each other, and a recording signal processing circuit. A reproduction signal processing circuit, a recording / reproduction switching circuit that connects the recording signal processing circuit to the fixed side winding during recording, and connects a reproduction signal processing circuit to the fixed side winding during reproduction, and the rotation side during recording A recording signal transmission circuit provided on the rotating drum side for connecting a winding to the recording / reproducing head, and an amplifier for transmitting the output of the recording / reproducing head to the rotating side winding during reproduction. A reproduction signal transmission circuit provided on the rotating drum side, a rectifying circuit constantly connected to the rotating side winding, and a rectifying circuit provided on the rotating drum side, and constantly connected to the rectifying circuit And a rechargeable power source provided on the rotary drum side and connected to a power source terminal of the amplifier of the reproduction signal transmission circuit, the recording signal processing circuit is connected to the recording signal transmission circuit. A rotary head type recording / reproducing apparatus, characterized in that the supplied recording signal is rectified by the rectifying circuit to charge the rechargeable power source. 2. A rotating drum, a recording head attached to the rotating drum, a reproducing head attached to the rotating drum, and a head amplifier connected to the reproducing head and provided on the rotating drum side. A recording signal processing circuit, a reproduction signal processing circuit, a recording rotary transformer provided between the recording signal processing circuit and the recording head, and a recording amplifier provided between the head amplifier and the reproduction signal processing circuit. A rotary transformer for reproduction, a rectifier circuit which is always connected to the rotary transformer for recording, and which is provided on the rotary drum side, and is constantly connected to the rectifier circuit so as to be charged by the output of the rectifier circuit. And a chargeable power source provided on the rotary drum side and connected to a power source terminal of the head amplifier, the recording signal processing circuit A rotary head type recording / reproducing apparatus, characterized in that the recording signal supplied from the recording rotary transformer is rectified by the rectifying circuit to charge the rechargeable power source.