JPH0664687B2 - Signal extraction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to magnetic recording / reproducing in which a magnetic head provided in a rotary drum machine such as a video tape recorder records and reproduces a signal on a magnetic recording medium. The present invention relates to a signal extraction device provided for a device or the like.

[Conventional technology]

Conventionally, for example, in a video tape recorder (hereinafter referred to as VTR) having a rotary drum mechanism, when recording a signal such as a video signal, the recording signal is transmitted to a rotary head which is a recording / reproducing head through a rotary transformer. While recording on the magnetic tape, at the time of signal reproduction, the signal recorded on the magnetic tape is read by the rotary head and similarly taken out via the rotary transformer.

However, in the configuration in which the recording signal and the reproduction signal are transmitted via the rotary transformer as described above, there are problems that the signal deterioration becomes large depending on the frequency band and that the S / N tends to become low.

Therefore, in order to solve the above-mentioned problems, a configuration has been proposed in which, instead of the above rotary transformer, signal transmission is performed by an electro-optical converting means, an optical fiber cable, and an electro-optical converting means.

In the case of such a configuration, as disclosed in Japanese Utility Model Laid-Open No. 53-63811 and Japanese Utility Model Laid-Open No. 58-173012, the electro-optical conversion means is provided on the side of the reproducing head, which is a rotary head. The fiber cable has one end facing the photoelectric conversion means or connected to the photoelectric conversion means, and the other end side inserted into a hollow rotary shaft that rotates together with the reproducing head, and the photoelectric conversion means is the optical fiber. It is provided on the fixing member so as to face the other end of the cable.

Further, in the case of the above-mentioned structure, it is necessary to stably enter the light from the optical fiber cable rotating together with the rotating shaft to the photoelectric conversion means provided in a fixed state.
Therefore, in the configuration of the above-mentioned Japanese Utility Model Laid-Open No. 58-173012 in which signals are reproduced by two reproducing heads, two optical fiber cables respectively corresponding to the reproducing heads are provided.
One end of each of these optical fiber cables is exposed from the peripheral wall portion at a midway position of the rotating shaft and faces each electro-optical converting means. Then, since the optical signal is emitted from each of the optical fiber cables on the optical axis that is concentric with the axis of the rotation axis, the other end portion side of the optical fiber cable has its center aligned with the axis of the rotation axis. In this state, they extend in opposite directions to face each photoelectric conversion means provided in a fixed state. This structure is also described in Japanese Utility Model Laid-Open No. 53-63811.

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional configuration, since the reproduction outputs of the two reproducing heads are taken out from one side and the other side of the rotary shaft, the power supply line for the output signal of the photoelectric conversion means is avoided by a member such as a rotary drum. However, it has a problem that the structure becomes complicated.

Therefore, it is an object of the present invention to provide a signal extracting device which can simplify the structure in a structure for extracting a signal of a reproducing head through an optical fiber cable.

[Means for Solving the Problems]

In order to solve the above problems, the signal extraction device of the present invention includes a plurality of reproducing heads which rotate in conjunction with a hollow rotating shaft and take out signals from a magnetic recording medium in sliding contact, and the reproducing heads. Correspondingly provided individually, electro-optical converting means for converting an electric signal outputted from each reproducing head into an optical signal, and electro-optical converting means respectively provided respectively corresponding to the electro-optical converting means Each optical fiber cable for transmitting an optical signal in one direction in the rotary shaft, and provided in the rotary shaft and concentric with the rotary shaft,
Incident light converging means for deflecting the optical signal transmitted by each optical fiber cable and converging it on an optical axis that is concentric with the axis of the rotation axis, and converged light output from the incident light converging means And a photoelectric conversion means for converting into an electric signal.

[Action]

According to the above configuration, the reproduction signals detected by the plurality of reproduction heads are converted into optical signals by the individual electro-optical conversion means and transmitted in one direction within the rotation axis by the individual optical fiber cables. Thereafter, the optical signal is deflected by the incident light converging means concentrically provided with the rotation axis, converges on the optical axis concentric with the axis of the rotation axis, and is converted into an electric signal by the photoelectric conversion means. It

As described above, in the configuration of the present invention, the optical signal transmitted in one direction in the rotation axis by each optical fiber cable, and the axis of the rotation axis by the incident light converging means provided concentrically with the rotation axis. Since the light is converged on the concentric optical axes, the light can be stably input from the optical fiber cable to the photoelectric conversion means. Further, since each signal reproduced by the plurality of reproducing heads is taken out from one side of the rotary shaft, that is, from the same position, it is not necessary to route the power supply line for the output signal by avoiding the member such as the rotary drum, and the structure is simplified. can do.

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

As shown in FIGS. 5 (a) and 5 (b), the VTR which is a magnetic recording / reproducing apparatus has a rotary drum mechanism including a fixed drum 7, a rotary drum 8 and a hollow rotary shaft 4. A rotary drum 8 is fixed to the rotary shaft 4, and a rotary transformer 5 and head supporting members 6a and 6a for supporting the recording / reproducing heads 6 and 6 connected to the rotary transformer 5 are fixed. These members are adapted to rotate with the rotation. A magnetic tape 9 as a magnetic recording medium is slidably contacted with the fixed drum 7 and the rotary drum 8, and recording / reproducing heads 6 and 6 provided at an angle of 180 ° are slidably contacted with the magnetic tape 9. It is configured.

Further, the VTR has a signal recording system configuration, that is, a recording signal processing unit 1 that performs a predetermined process for appropriately recording a recording signal such as a video signal, and recording performed by the recording signal processing unit 1. An FM modulator 2 that FM-modulates a signal and a recording amplifier 3 that amplifies the output of the FM modulator 2 are provided. And
The recording amplifier 3 is connected to the rotary transformer 5 via a changeover switch 23 that switches between a recording operation and a reproducing operation. Further, the VTR is connected to the changeover switch 23 as a configuration of a signal reproducing system, and the rotary transformer 5 is connected.
A reproduction amplifier 10 for amplifying a reproduction signal from the recording / reproducing head 6/6 obtained via the recording / reproducing head 6, and a reproduction in which the amplified reproduction signal corresponding to the recording / reproducing head 6/6 is appropriately switched and arranged into a predetermined reproduction signal. FM of output of equalizer 11 and reproduction equalizer 11
An FM demodulator 12 that demodulates a reproduced signal, and a reproduced signal processing unit 13 that performs appropriate processing on the reproduced signal output from the FM demodulator 12 and sends the processed signal to a monitor.

On the other hand, the rotary drum mechanism is provided with a signal take-out device. As shown in FIG. 1, the signal take-out device is slidably in contact with the magnetic tape 9 and rotates with the rotary shaft 4 for reproduction only. 14 are arranged at an angle of 180 °, and these read-only heads 14 and 14 are respectively connected to electro-optical converters 15 and 15 for converting electric signals into optical signals. The electro-optical converters 15 and 15 are fixed to the rotary drum 8 and are provided close to the read-only heads 14 and 14. The above-mentioned electro-optical converter 15
15 Fiber Optic Cable 16 which forms the transmission medium of optical signal of output 16
・ 16 are connected, and these optical fiber cables 16 ・ 16 are
An incident side plastic lens 17 housed concentrically with the rotating shaft 4 is connected to the upper portion of the rotating shaft 4. The plastic lens 17 on the incident side is set to have an appropriate length so that the optical signal transmitted from the optical fiber cables 16 and 16 can be emitted from the lower end face as shown in FIG. 2 or 3. The parallel light is emitted from the light source. That is, the refractive index on the optical axis 18 coinciding with the axis of the rotating shaft 4 is n ₀ , and the refractive index distribution constant is A relational expression that holds when the distance from the light source to the incident end face is l ₁ , the distance from the emission end face to the focus is l ₂ , and the length of the incident side plastic lens 17 is Z ₁ . In, the parallel light can be obtained by selecting the length Z ₁ of the incident side plastic lens 17 so that l ₂ = 0.

At the lower end of the rotary shaft 4 below the incident side plastic lens 17, an output side plastic lens 19, which constitutes an incident light converging means together with the incident side plastic lens 17, is housed concentrically with the rotary shaft 4. Has been done. By setting the output side plastic lens 19 to have an appropriate length, as shown in FIG. 4, the parallel light emitted from the input side plastic lens 17 is separated by l ₃ from the output end face of the lower end face. It is adapted to converge on the axis 18 to form a focal point 20. The distance l ₃ from the emitting end surface of the emitting side plastic lens 19 to the focal point 20 is Z _{2 where} the length of the emitting side plastic lens 19 is It can be obtained by the relational expression of.

The distance between the two lenses 17 and 19 is determined in consideration of the insertion loss in the configuration of the system that obtains the parallel light as described above, and even if it is set to 40 to 50 mm based on the published value, the insertion loss does not increase. Does not happen. Therefore, in consideration of this value, the exit side plastic lens 19 is provided at the lower end of the rotary shaft 4 and the position of the entrance side plastic lens 17 is determined. Instead of the incident side plastic lens 17 and the output side plastic lens 19, for example, these plastic lenses 17
Selfoc lens with the same function as 19 (brand name)
It is also possible to use

Further, at the position of the focal point 20 below the emission side plastic lens 19, a photoelectric converter for receiving the emission light from the emission side plastic lens 19 and converting it into an electric signal.
21 are provided. The arrangement position of the photoelectric converter 21 is not limited to the above position, and may be between the emission end face of the emission side plastic lens 19 and the focal point 20. Light above
The electric converter 21 is fixed to the fixed drum 7 and is connected to the regenerative amplifier 10 which constitutes a signal reproducing system of the VTR.

In the above-mentioned configuration, in the signal recording system, the recording signal such as a video signal is processed by the recording signal processing unit 1, FM modulated by the FM modulator 2, amplified by the recording amplifier 3, and then rotated. It is transmitted to the recording / reproducing heads 6 and 6 which are also interlocked with the rotary shaft 4 via the rotary transformer 5 which is interlocked with 4 and recorded as a magnetization pattern on the magnetic tape 9. Further, in the signal reproducing system, the signal recorded on the magnetic tape 9 is converted into an electric signal by the recording / reproducing heads 6 and 6 and taken out, and then transmitted through the rotary transformer 5 from the rotary drum 8 side to the fixed drum 7 side. . Then, after being amplified to a specified voltage by the reproduction amplifier 10, demodulated by the FM demodulator 12 through the reproduction equalizer 11, processed into a predetermined reproduction signal by the reproduction signal processing unit 13 and sent to the monitor. There is.

On the other hand, on the signal take-out device side, the reproduction-only heads 14 and 14, the electro-optical converters 15 and 15,
Optical fiber cable 16, 16, incident side plastic lens
17 and the exit side plastic lens 19 are rotated.

Here, when the signal extracting device is operated, the signal recorded on the magnetic tape 9 is extracted as a reproduction signal of an electric signal by each reproduction-only head 14. This reproduction signal is converted into an optical signal by the electro-optical converters 15 and 15 and transmitted to the incident side plastic lens 17 through the respective optical fiber cables 16 and 16. The optical signal incident on the incident side plastic lens 17 is sent out as parallel light from the emission side end face and is incident on the emission side plastic lens 19. Then, after being emitted from the emission side plastic lens 19 so as to be converged at the focal point 20, it is incident on the photoelectric converter 21 and converted into an electric signal. After that, the reproduced signal is input to the reproduction amplifier 10, subjected to predetermined processing in each part of the signal reproduction system, and then transmitted to the monitor.

Since the signal reproducing operation in the signal extracting device described above is independent of the original recording / reproducing operation of the VTR, it can be performed in parallel with the recording / reproducing operation.

In addition, in this signal extraction device, both optical fiber cables 16
An optical signal transmitted in one direction in the rotating shaft 4 at 16 passes through an incident side plastic lens 17, and then is converged by an emitting side plastic lens 19 on an optical axis that coincides with the axis of the rotating shaft 4. , Is incident on the opto-electric converter 21, so the optical fiber cable 16 on the side of the rotating shaft 4 that rotates is converted from the opto-electric converter 21.
The optical signal is stably transmitted to 21. Further, since the signals reproduced by the reproduction-only heads 14 and 114 are taken out from one side of the rotary shaft 4, that is, from the same position, it is not necessary to route the power supply line for the output signal by avoiding the member such as the rotary drum 8. , The structure can be simplified. That is, the structure of the device is simplified while ensuring the function of stably extracting the signals reproduced by the reproduction-only heads 14 and 14.

In the present embodiment, the configuration is shown in which the reproduction signal of one channel is taken out, but the electro-optical converter 15 and the opto-electric converter are shown.
Since 21 and 21 are provided according to the number of channels, and the step-in-death type optical fiber, homographic, and both plastic lenses 17 and 19 are provided, multi-channel signal extraction can be performed.

Second Embodiment Another embodiment of the present invention will be described below with reference to FIG. The members having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

The signal extraction device according to the present embodiment has an incident side plastic lens 17 and an emission side plastic lens shown in FIG.
Instead of 19, a single plastic lens 22 is provided as an incident light converging means. This plastic lens 22
Inside, the incident light is appropriately deflected so that the light propagates by repeating the amplitude of a constant cycle.

The length is set so that the optical signal emitted from the emission end face of the lower end face of the plastic lens 22 forms the focal point 20 at an appropriate position on the optical axis 18. Therefore, the incident side plastic lens 17 and the emitting side plastic lens 19
It has the same function as the configuration consisting of.

〔The invention's effect〕

As described above, the signal extraction device of the present invention includes a plurality of reproducing heads that rotate in conjunction with the hollow rotation shaft to extract signals from the magnetic recording medium that is in sliding contact with each other. And an electro-optical converting means for converting an electric signal output from each reproducing head into an optical signal, and an electro-optical converting means respectively provided corresponding to each electro-optical converting means,
Each optical fiber cable that transmits the optical signal output from each electro-optical conversion means in one direction within the rotation axis, and is provided in the rotation axis and concentrically with the rotation axis, and is transmitted through each optical fiber cable. Incident light converging means for deflecting the generated optical signal and converging it on an optical axis concentric with the axis of the rotation axis, and photoelectric conversion for converting the converged light output from the incident light converging means into an electric signal. And means.

As a result, the optical signal transmitted in one direction within the rotation axis by each optical fiber cable is transmitted to the optical axis concentric with the axis of the rotation axis by the incident light converging means provided concentrically with the rotation axis. Since the light is converged, the light can be stably incident on the photoelectric conversion unit from the optical fiber cable. Also,
Since each signal reproduced by a plurality of reproducing heads is taken out from one side of the rotary shaft, that is, from the same position, it is not necessary to route the power supply line for the output signal by avoiding a member such as a rotary drum, and simplifying the structure. You can

That is, the configuration of the present invention has the effect of simplifying the structure while ensuring the function of stably extracting the signals reproduced by the plurality of reproducing heads.

[Brief description of drawings]

1 to 5 show one embodiment of the present invention. FIG. 1 is an explanatory view showing a signal extracting device according to the present invention, and FIG. 2 is an incident side plastic shown in FIG. FIG. 3 is an explanatory view of the lens, FIG. 3 is an explanatory view of another incident side plastic lens, FIG. 4 is an explanatory view of the exit side plastic lens shown in FIG. 1, and FIGS. 5 (a) and 5 (b) are respectively A schematic explanatory view and a block diagram showing a main part of the video tape recorder,
FIG. 6 is an explanatory view of a signal extracting device showing another embodiment of the present invention. 4 is a rotary shaft, 5 is a rotary transformer, 6 is a recording / reproducing head,
7 is a fixed drum, 8 is a rotating drum, 9 is a magnetic tape (magnetic recording medium), 14 is a read-only head, 15 is an electro-optical converter (electro-optical converting means), 16 is an optical fiber cable, and 17 is an incident side plastic. Lens (incident light converging means), 18 optical axis,
Reference numeral 19 is an exit side plastic lens (incident light focusing means), 20
Is a focal point, 21 is a photoelectric converter (photoelectric conversion means), and 22 is a plastic lens (incident light converging means).

Claims (1)

[Claims] 1. A plurality of reproducing heads, which rotate in conjunction with a hollow rotating shaft and take out signals from a magnetic recording medium in sliding contact, and individual reproducing heads provided corresponding to these reproducing heads, respectively. And an electro-optical conversion means for converting an electric signal output from the optical signal into an optical signal, and an optical signal output from each electro-optical conversion means is individually provided corresponding to each of the electro-optical conversion means and transmitted in one direction within the rotation axis. Each optical fiber cable is provided in the above-mentioned rotating shaft and concentrically with the rotating shaft, and deflects the optical signal transmitted by each optical fiber cable to form a concentric axis with the rotating shaft. A signal extraction device comprising: an incident light converging means for converging on an optical axis; and a photoelectric conversion means for converting the converged light output from the incident light converging means into an electric signal.