JP2690325B2 - Information recording / reproducing device - Google Patents

Description

The present invention relates to an information recording / reproducing apparatus such as a rotary head type magnetic recording / reproducing apparatus, and more particularly to a power supply unit for an amplifier rotating together with a transducer. Is.

[Prior Art] FIG. 4 is a block diagram of a conventional information recording / reproducing apparatus disclosed in, for example, Japanese Patent Publication No. 57-37924, in which (1) is a video head and (2) is an amplifier. , (3) is a rotary transformer, (4) is a signal processing circuit, (5) is a power source oscillator (hereinafter referred to as OSC), (6) and (7) are power source transmission coils, and (8) is for rectification. A diode, (9) is a smoothing capacitor, (10) and (11) are signal transmission capacitors, which include the video head (1), the amplifier (2), the signal transmission capacitor (10), and the rectifying diode (8). The smoothing condenser (9) rotates integrally. Also, the above OSC
The high frequency power of (5) is the power transmission coil (6),
(7), through the rotary transformer (3), further rectified by the diode (8) and the smoothing capacitor (9), and supplied to the amplifier (2).

 Next, the operation of the above configuration will be described.

The signal from the video head (1) is amplified by the amplifier (2) and then input to the signal processing circuit (4) via the signal transmission capacitor (10), the rotary transformer (3) and the signal transmission capacitor (11). To be done.

At this time, high frequency power having a frequency separable from the frequency of the signal reproduced by the video head (1) is transmitted from the OSC (5) to the power transmission coil (6), the rotary transformer (3), and the power transmission. The amplifier (2) is operated by being rectified by the diode (8) and the smoothing capacitor (9) through the coil (7) and then supplied to the amplifier (2). In this way, the signal from the video head (1) is amplified and input to the rotary transformer (3), so that the level of the reproduced signal is prevented from lowering, the S / N is improved, and the reproduced image quality is improved.

[Problems to be Solved by the Invention] Since the conventional information recording / reproducing apparatus is configured as described above, although it is effective in improving the S / N, it is affected by the high frequency power supplied to the amplifier (2). Therefore, there is a problem that frequency interference appears on the playback screen.

That is, the power supplied from the OSC (5) to the amplifier (2) needs to be at least about 0.1 W. On the other hand, the reproduction voltage from the video head (1) is a weak voltage of about 0.1 mV, and the output power from the amplifier (2) is 0.001W.
It is about. Therefore, the frequency of the playback signal and the OSC
Even if the frequency of the power supplied from (5) is separable, it is inevitable that the high frequency output from the OSC (5) is mixed into the signal processing circuit (4). Therefore, there is a problem in that the reproduction screen is disturbed by the frequency and the quality of the reproduced image is deteriorated.

The present invention has been made to solve the above problems, and it is possible to reduce the disturbance appearing on the reproduction screen and improve the quality of the reproduced image by considering the supply period of the high frequency power to the amplifier. It is an object of the present invention to provide an information recording / reproducing apparatus capable of performing the above.

[Means for Solving the Problems] An information recording / reproducing apparatus according to the present invention is an information recording / reproducing apparatus for recording / reproducing image information by a rotating transducer, and an amplifier rotating together with the transducer, and high-frequency power supplied to the amplifier. An oscillator for supplying power, a separating means for separating a horizontal synchronizing signal for image reproduction based on image information recorded and reproduced via the transducer, and recording of the image information from a blanking period including the horizontal synchronizing signal. Power supply control means for controlling the high frequency power of the power source oscillator so that the power supply level to the amplifier is lowered during the reproduction period.

[Operation] According to the present invention, the level of the high-frequency power supplied from the OSC to the amplifier is automatically controlled so as to be high during the blanking period accompanied by the synchronization signal and low during the information recording / reproducing period. So especially
It is possible to prevent high frequency power from entering the signal processing circuit or the like when reproducing information as much as possible, and reduce the occurrence of frequency interference on the reproduction screen.

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

FIG. 1 is a block diagram showing the configuration of the essential parts of an information recording / reproducing apparatus according to an embodiment of the present invention. In FIG.
(4) is a signal processing circuit. This signal processing circuit (4) is connected to the rotary transformer (3) through a signal transmission capacitor (11) as shown in FIG. ) And an FM demodulator (13), and has an output terminal (14) for outputting a reproduction luminance signal having a waveform as shown in FIG. 2 (a).

Reference numeral (15) is a sync separation circuit for separating a horizontal sync signal as shown in FIG. 2 (b) from the reproduction luminance signal (a).
(5) is an OSC, which is composed of an oscillator (16), a gate circuit (17) and a power amplifier (18), and is output from the oscillator (16) as shown in FIG. 2 (c). The high frequency power having a waveform as shown in Fig. 2 is controlled by the horizontal synchronizing signal (b) input to the gate circuit (17), and the gate circuit (17) and the power amplifier (18) are used to control the high frequency power in Fig. 2 (d). The high frequency power having the waveform as shown is output. The other structure is the same as that of the conventional example shown in FIG.

 Next, the operation of the above configuration will be described.

Playback voltage applied to the limiter (12) of the signal processing circuit (4) from the video head (1) through the amplifier (2), the signal transmission capacitor (10), the rotary transformer (3), and the signal transmission capacitor (11). Is subjected to amplitude control in the limiter (12) and then input to the FM demodulator (13) for demodulation, and a reproduction luminance signal as shown in FIG. 2 (a) is output to the output terminal (14). . This reproduction luminance signal (a)
Is also input to the sync separation circuit (15) to separate the horizontal sync signal as shown in FIG. 2 (b), and this horizontal sync signal (b) is fed to the gate circuit (17) of the OSC (5). input.

On the other hand, from the oscillator (16) of the OSC (5), see FIG. 2 (c).
The high frequency power as indicated by is output and input to the gate circuit (17). The gate circuit (17) gates the output of the high-frequency power (c) from the oscillator (16) each time the horizontal synchronizing signal (b) from the synchronization separating circuit (15) is input, and the gate circuit (17) shown in FIG. Electric power having a waveform as shown in (d) is output, and this is amplified by the power amplifier (18) and output.
Therefore, the rotary transformer (3) has the above OSC.
From (5), the output is given only in the horizontal synchronizing signal period (D1), and the output is not given in the other periods (D2).

Further, upon receiving an output as shown in FIG. 2 (d) from the rotary transformer (3), the diode (8) and the smoothing capacitor (9) operate, and the voltage of this smoothing capacitor (9) is shown in FIG. e). That is, the input power to the diode (8) is intermittent as shown in FIG. 2 (d), but if the capacity of the smoothing capacitor (9) is set to a large value, the input power to the diode (8) will be increased. Even in the non-existing period, the smoothing capacitor (9) supplies the DC voltage as shown in FIG. 2 (e) to the amplifier (2).

As described above, during the information recording / reproducing period (D2), the level of the power supplied to the amplifier (2) is lowered to reduce the frequency interference on the screen. By increasing the level of the power supplied to the amplifier (2) during the horizontal synchronizing signal period (D1), the high frequency output is mixed into the signal processing circuit (4) and interferes with the screen.
This period is a blanking period and there is no visual problem. Also, when the output of the FM demodulator (13) is absent when the video head (1), rotary transformer (3), etc. rises in rotation, the gate circuit (17) turns on, but in this case as well, it interferes with the screen. The inconvenience of does not occur.

FIG. 3 is a block diagram showing the configuration of the main part of an information recording / reproducing apparatus according to another embodiment of the present invention. In FIG. 3, the point different from the embodiment shown in FIG. 1 is OSC (5). In this configuration, in addition to the gate circuit (17), an attenuator (19) is inserted in parallel between the oscillator (16) and the power amplifier (18). Since other configurations are the same as those of the embodiment shown in FIG. 1, the same reference numerals are given and the description thereof will be omitted.

Next, the operation of the configuration shown in FIG. 3 will be described.

Output (c) of oscillator (16) is horizontal sync signal period (D1)
While being given to the power amplifier (18) as it is, it is given after being attenuated by the attenuator (19) in the other period (D2). Therefore, the power amplifier (18) outputs electric power having a waveform as shown in FIG. 2 (f). That is, the output from the OSC (5) during the information recording / reproducing period (D2) is small, so that the interference with the screen can be reduced and the charge given to the smoothing capacitor (9) can be reduced.

According to the other embodiment shown in FIG. 3, compared with the embodiment shown in FIG. 1, although a little more interference appears on the screen, it is possible to increase the power supply capacity to the amplifier (2). It will be possible.

Although the output of the oscillator (16) is controlled by using the gate circuit (17) in the above embodiment, the oscillation of the oscillator (16) itself may be interrupted or the oscillation intensity may be changed. The same effect as that of the above embodiment is obtained.

Further, in the above embodiment, one rotary transformer (3) is used.
Thus, the reproduction signal is transmitted and the electric power is transmitted to the amplifier (2), but the same effect as in the above embodiment can be obtained even if separate rotary transformers are used.

Further, instead of the rotary transformer, a signal transmission means using electrostatic capacitance or a signal transmission means using light may be used.

Furthermore, the period during which the output of the OSC (5) is reduced may be set slightly wider over the horizontal synchronization signal period (D1) and may be set as the full width of the blanking period.

As described above, according to the present invention, by controlling the supply level of the high frequency power from the OSC to the amplifier so as to be lower than other periods when the image appears on the reproduction screen, It is possible to improve the quality of the image by preventing the frequency interference from appearing on the reproduction screen while keeping the power supplied to the amplifier at a necessary and sufficient value.

[Brief description of the drawings]

FIG. 1 is a block diagram of essential parts showing the structure of an information recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining the operation, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a block diagram of the main part of FIG. 4, and FIG. 4 is a block diagram of a conventional information recording / reproducing apparatus. (1) …… Video head, (2) …… Amplifier, (3)…
… Rotary transformer, (4) …… Signal processing circuit, (5)
…… OSC, (16) …… oscillator, (17) …… gate circuit,
(18) …… Power amplifier. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. An information recording / reproducing apparatus for recording / reproducing image information by a rotating transducer, an amplifier rotating together with the transducer, a power source oscillator for supplying high frequency power to the amplifier, and recording / reproducing via the transducer. Separation means for separating a horizontal synchronizing signal for image reproduction based on the image information, and a power supply level to the amplifier is lower during a recording / reproducing period of the image information than a blanking period including the horizontal synchronizing signal. An information recording / reproducing apparatus comprising: a power supply control means for controlling high frequency power of the power supply oscillator.