JPS595980B2 - tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A tape recorder employing a two-head system cannot directly monitor (tape monitor) the recording state of an input signal on the tape due to its configuration.

Therefore, conventionally, the recording level has been adjusted by checking the fluctuation of the level meter or by the operator's intuition. Therefore, in the case of a portable tape recorder, the input level tends to change irregularly as the object to be recorded moves and so on. Therefore, in order to always achieve good recording conditions, it is necessary to
It is necessary to constantly observe the level meter. However, such a thing is simply impossible. It goes without saying that in order to obtain a good recording condition, it is necessary to satisfy conditions such that the input signal does not reach the saturation level of the tape and the tape noise does not increase too much. In consideration of this point, the present invention is configured so that even a tape recorder employing a two-head system can obtain a monitoring condition almost the same as a tape monitor, so that input signals can be recorded at a good recording level at all times. It is something.

The tape recorder of the present invention will be described below with reference to the drawings, but in this example, a case where the tape recorder is applied to a stereo tape recorder employing the two-head system as described above will be shown.

In Figure 1, IR is the recording system for the right channel, and IL is the recording system for the right channel.
indicate the recording system of the left channel, respectively. Since these are all well known, only the name of one system IR will be written and the other system will be omitted. This method will continue to be used for common parts. 2R is the microphone, 3R is the front amplifier, 4R is the line amplifier,
5R is a recording amplifier, and 6R is a recording/playback head.

Further, TR is the microphone volume. These recording system IR
, the input signal to be recorded obtained from the IL is added to the table noise output (for convenience of explanation, this output will be referred to as the filter output hereinafter), which has almost the same frequency components as the tape noise, and this is the normal tape monitor signal. used as. That is, a pseudo tape monitor output is created. Next, we will explain the circuit for obtaining this pseudo tape monitor output. In this example, 11 is a noise generation source, and in order to obtain white noise with flat frequency characteristics, the connection is as shown in the figure with an open collector. A transistor is used that takes In addition,
A Zener diode may be used instead of a transistor. Since the noise obtained from the noise source 11 is output with almost the same frequency characteristics as the tape noise,
The signal is supplied to the filter circuit 20 at the subsequent stage. Filter circuit 2
0 has a transistor Q1 for amplification, and a parallel circuit 12 consisting of a resistor 12a and a capacitor 12b that mainly determines low frequency components is connected in series to the collector side of the transistor Q1, and a parallel circuit 12 that mainly determines low frequency components. A series circuit 13 consisting of a capacitor 13a and a resistor 13b or 13b' as shown in the figure for determining the components is connected.

The series circuit 13 is provided with a switch SWa for switching between the Dolby one-way system and the normal recording/reproducing system. The switching shown in the figure uses the Dolby one-way system. Therefore, the constants of each of the series circuit 12 and the parallel circuit 13 are appropriately selected to give almost the same frequency characteristics as tape noise.

Curve a in Fig. 2 shows the frequency characteristics of the filter output obtained from this filter circuit 20, and this has a characteristic in which the low frequency range is enhanced and the high frequency range is attenuated, taking into account the characteristics of the recording equalizer, etc. There is. Therefore, this curve a shows the frequency characteristics of the tape noise, but if the type of tape used is different, especially as in the force set, the frequency characteristics of the tape noise will also be different, so in that case, each of the above-mentioned All you have to do is match the constant to the tefsoise of the tape you are using.

The filter output having such frequency characteristics is supplied to the mixing circuits 16R, 16L provided corresponding to each recording system together with the line amplifier output of each recording system 1R, 1L, and is mixed with a desired mixing ratio. Mixed and synthesized.

Therefore, since the mixed output has almost the same frequency characteristics as the output reproduced through the tape system, this mixed output will be referred to as a tape monitor output in the following explanation. Therefore, if you listen to the tape monitor output during recording with earphones, headphones, etc., you can easily judge whether the recording level of the input signal is appropriate or not. By adjusting the microphone polyurethanes 7R and 7L, an appropriate recording state can be maintained at all times.
Next, a specific circuit configuration for tape monitoring will be explained, but since a conventionally known mixing circuit 16R can be used, a detailed explanation of the specific circuit configuration will be omitted. Also, Q2 is a mixing transistor, and a tape monitor output is taken out from its collector via a capacitor 17.

In this example, source monitoring is also possible, so in order to monitor the line amplifier output of recording system 1R, this output and the tape monitor output mentioned above are connected to monitor switches SW8, SWI. After one output is manually selected at , it is supplied to amplifiers 18R and 18L.

This amplifier 18R is a so-called 3-head type amplifier.
These are provided to drive the tape monitor in the recorder, a headphone (not particularly shown) for listening to the output, and level meters 21R and 21L for displaying the monitor output level, respectively.Q3 is a transistor for amplification;
22 is a smoothing circuit for smoothing the monitor output, and its output is supplied to the level meter 21R.

The monitor output before being smoothed is supplied via a transformer 23 to a headphone jack (not specifically shown). Note that in this example, a monitoring output terminal is provided to monitor the recording state during dubbing, for example. Reference numerals 24R and 24L indicate these output terminals, and monitor outputs obtained from monitor switches SWO and SWl are used. As explained above, in the present invention, a filter output having almost the same frequency characteristics as that of TEF SOIS is obtained, and this is synthesized with the input signal to be recorded.
The device is configured to monitor this composite signal.
In this way, first, it is possible to electrically form a filter output with almost the same frequency characteristics as that of tape noise, so if the input signal is synthesized with this filter output, the output obtained through the tape system can be (playback output) and its characteristics are almost the same, the combined output can be used as a tape monitor output. Therefore, by adjusting the level of the input signal while listening to the output of this pseudo tape monitor using a headphone or the like, the input signal can be recorded at a good recording level at all times. In this case, since the tape system is not interposed in the source monitor, it is not very advisable to determine the level of the input signal based on the source monitor. This is because, as mentioned at the beginning, the level setting is performed without taking into account conditions such as tape noise and tape saturation level, which are required to achieve good recording conditions. For the above reasons, the present invention is particularly suitable for application to a two-head type tape recorder that cannot be equipped with a tape monitor mechanism. However, it goes without saying that the present invention can also be applied to a three-head tape recorder.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a main part of a tape recorder according to the present invention, and FIG. 2 is a frequency characteristic curve diagram of a filter output for explaining its operation. 1R, 1L are recording system, 4R, 4L are line amplifier, 6R
, 6L is a head, 11 is a noise source, 20 is a filter circuit, 12 is a parallel circuit, 13 is a series circuit, 16R, 16
L is a mixing circuit, SW8, SWl are monitor switches, 18
R and 18L are amplifiers, and 21R and 21L are level meters.

Claims (1)

[Claims] 1. A device that takes a noise source and the noise from this noise source as input, and outputs the frequency characteristics of the input noise almost the same as the frequency characteristics of tape noise.
A tape that is provided with a filter circuit having characteristics such as enhancing the low frequency range and attenuating the high frequency range, and is configured to synthesize the filter output obtained from this filter circuit and the input signal to be recorded to obtain a monitor output. recorder.