JPH04114579A - Very low frequency signal recording video tape recorder - Google Patents

Abstract

PURPOSE:To record a very low frequency signal such as heart sound on a video tape by providing a means which records and reproduces the extremely low frequency signal. CONSTITUTION:In the case of the signal of a very low frequency band of 1Hz-20Hz, it passes through a DC amplifier 1, it is added to an FM amplifier through a previously selected B-side contact point and it is recorded in the video tape. As to reproduction, a recording/reproducing head 6 raises the signal recorded in the video tape as a reproduction signal and a reproduction amplifier 7 amplifies it to an appropriate size. The amplified reproduction signal is added to an FM demodulator 8 and is demodulated to a desired signal. In the case of the very low frequency band signal, the demodulated signals selectively pass a B'-side by a switch 9 and they are amplified in an audio band amplifier 10 and a DC amplifier 11, whereby they are outputted to sound output. Thus, heart sound and the like can be recorded and they can effectively be used as medical treatment data since the very low frequency signal of about several Hz can be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an extremely low frequency signal recording device in a medical video tape recorder.

[Prior Art] Conventionally, medical video tape recorders have mainly been used for recording images with cameras and for treatment and case research. In this case, no special considerations were made for audio recording, and the audio was recorded at the human audible frequency range of 207 to 20 KHz.
is the recordable frequency band. In recent years, in the medical field, studies have begun to record heartbeats along with images to improve the effectiveness of treatment. The frequency of the heartbeat is around 17, which is an extremely low local signal, and cannot be recorded with a conventional video tape recorder.

[Problem to be solved by the invention] The conventional technology does not take into consideration the recording of extremely low frequency signals;
There was a problem that signals such as heart sounds could not be recorded.

The object of the invention is to record very low frequency signals such as heart sounds on videotape.

[! Means for Solving a Problem] In order to achieve the above object, an extremely low frequency signal is FM modulated and this FM modulated signal is recorded on a videotape.

[Operation] In FIG. 1, DC amplifiers 1 and 11 amplify and pass very low frequency signals without distortion. The FM modulator 4 is
The signal is modulated into an FM signal.

The FM demodulator 8 demodulates the FM modulated signal into an extremely low frequency signal.

[Example] An example of the present invention will be described below with reference to FIG. FIG. 1 shows the parts of the video tape recorder related to the present invention, and the other parts are the same as those of a general video tape recorder.

Now, a signal having a band of 1Hz to 20K) is input to the audio input. In the case of a normal audio signal in the audible band of 20 Hz to 20 KHz, the audio input signal passes through the audible band amplifier 2, and then the input signal is sent to the A side in the case of the audible band, or to the very low frequency side, depending on the band of the input signal. In the case of a band, the B side is selected.The signal is applied to the FM modulator 4 through the A side contact of the switch 3, and after being FM modulated, it is amplified by the recording amplifier 5.
It is recorded onto a videotape via the recording/reproducing head 6.

Also, in the case of signals in the ultra-low frequency band of 17 to 20 kHz.

After passing through the DC amplifier 1, the signal is applied to the FMJll@ unit via a preselected B-side contact, and then recorded on videotape via the same path. For reproduction, the recording/reproducing head 6 induces a signal recorded on the video tape as a reproduction signal, and the reproduction amplifier 7 amplifies the signal to an appropriate level. The amplified reproduction signal is applied to the FM demodulator 8 and demodulated into a desired signal. The demodulated signal is selectively passed through the A' side in the case of an audible band signal and the B' side in the case of an extremely low frequency band signal by the switch 9, and is amplified by an audible band amplifier 10 and a DC amplifier 11. Output to audio output. In addition, as another example, the amplifiers 2 and 11
It is also possible to replace the amplifier with a broadband amplifier including direct current, and in this case, the switches 3 and 9 are also unnecessary, resulting in a simple configuration.

[Effects of the Invention] According to the present invention, it is possible to record ultra-low frequency signals of approximately several digits, so heart sounds and the like can be recorded and effectively utilized as treatment data.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention. Explanation of symbols 1...DC amplifier, 2...Audio band amplifier, 3...
・Switch, 4...FM modulator, 5...Recording amplifier, 6...Head, 7...Reproduction amplifier, 8...FM demodulator, 9...Switch, 10...Audio band amplifier, 11
...DC amplifier.

Claims (1)

[Claims] 1. An ultra-low frequency signal, characterized in that a magnetic recording and reproducing device for recording and reproducing video and audio on a magnetic tape is provided with means for recording and reproducing an ultra-low frequency signal. Recording videotape recorder.