JPH01150280A - Recording device - Google Patents

Abstract

PURPOSE:To improve picture quality at the time of reproducing and to simplify the constitution of the title device by superposing an amplitude control signal to a current control terminal of a recording current control circuit. CONSTITUTION:A voltage signal obtained by superposing a recording current control signal set up by a resistor 7 to an amplitude control signal corresponding to the level of a brightness signal outputted from a level adjusting circuit 5 is supplied to the current control terminal 6a of the recording current control circuit 6 through a buffer circuit 12 and the circuit 6 controls recording current and the amplitude of a recording signal. Thereby, a brightness signal whose amplitude is modulated is recorded from a magnetic head 11 to a magnetic tape and the side band of a video signal obtained by reproducing the magnetic tape is strengthened, so that an image obtained at the time of reproducing can be improved and the constitution of the device can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording device suitable for use in, for example, a video tape recorder (VTR).

[Summary of the invention]

According to the present invention, in a recording device such as a VTR having a recording current control circuit provided with a current control terminal, good recording is achieved by superimposing an amplitude control signal on the current control terminal. , amplitude modulation for , can be performed with a simple configuration.

[Conventional technology]

Conventionally, when recording a frequency modulated wave such as a video signal on a magnetic tape, if the frequency modulated wave is amplitude-modulated so that the higher the frequency, the smaller the amplitude, when recorded on the tape and played back from the tape, the amplitude modulation is It is known that the sideband is enhanced by the conversion effect from phase modulation to phase modulation.

In this case, a configuration as shown in FIG. 3 has been proposed as a configuration for performing this amplitude modulation during recording with a VTR (Japanese Patent Laid-Open No. 62-32782). In FIG. 3, (1) indicates a luminance signal input terminal, and after the luminance signal obtained at this luminance signal input terminal (1) is pre-emphasized by an emphasis circuit (2), an FM modulation circuit (3) is used. ), and the FM modulation circuit (3) performs FM modulation for recording. The modulated signal output from this FM modulation circuit (3) is then supplied to the amplitude modulation circuit (4).

Further, the pre-emphasized luminance No. 13 outputted by the pre-emphasis circuit (2) is supplied to the level adjustment circuit (5), and the voltage signal as an amplitude control signal outputted by the level adjustment circuit (5) is subjected to amplitude conversion. It is supplied to the amplitude control signal input terminal of the circuit (4). By doing so, the amplitude modulation circuit (4) changes the amplitude of the FM modulation signal according to the level of the luminance signal. (4)
The luminance signal outputted by the recording signal amplifier (6) is supplied to the recording signal amplifier (6). In this case, the recording current control circuit (6) is generally composed of an IC, and a predetermined voltage signal is supplied to the current control terminal (6a) of the control circuit (6) via a variable resistor (7). be. The current value of the luminance signal modulated according to the signal obtained at the current control terminal (6a) is kept constant by this recording current control circuit (6). ) is supplied to one mixed signal input terminal of the mixer (8).

Then, the chroma signal obtained at the chroma signal input terminal (9) is supplied to the other mixed signal input terminal of the mixer (8), and this mixer (8) converts it into a video signal for recording. , is supplied to the magnetic head (11) via an amplifier (10). The video signal is then recorded on a magnetic tape (not shown) using the magnetic head (11).

In this way, by performing amplitude modulation in the amplitude modulation circuit (4), it is possible to strengthen the sidebands during playback of the video signal recorded on the magnetic tape, and improve the image quality during playback. can.

[Problem that the invention seeks to solve]

However, when amplitude modulation is performed using the amplitude modulation circuit (4), F
The phase of the M-modulated luminance signal may shift, which adversely affects the image quality during playback. Furthermore, when the amplitude modulation circuit (4) is connected in this way, there is a problem that the configuration becomes more complicated.

In view of these points, it is an object of the present invention to enable good recording amplitude modulation with a simple configuration.

[Means for solving problems]

For example, as shown in FIG. 1, the recording device of the present invention includes a recording current control circuit (6) provided with a current control terminal (6a), in which an amplitude control signal is superimposed on the current control terminal (6a). It was designed to do so.

[Effect]

According to the recording device of the present invention, since the recording current control circuit (6) performs amplitude modulation of the recording signal, there is no need for an amplitude modulation circuit, the circuit configuration is simplified, and the recording current control circuit (6) ) does not change the phase of the recorded signal, so good amplitude modulation is performed that reproduces with good image quality.

〔Example〕

An embodiment of the recording device of the present invention will be described below with reference to FIGS. 1 and 2.
Let me explain with reference to the diagram. In FIGS. 1 and 2, parts corresponding to those in FIG. 3 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this example, as shown in FIG.
) directly supplies the FM-modulated luminance signal to the recording current control circuit (6). The pre-emphasized luminance signal output by the pre-emphasis circuit (2) is then supplied to a level adjustment circuit (5), which creates a voltage signal according to the level of the luminance signal. The voltage signal output from this level adjustment circuit (5) is then supplied to the buffer circuit (12).
A voltage signal obtained at a movable terminal of a variable resistor (7) connected to a DC power source is supplied to a buffer circuit (12). This buffer circuit (12) is connected to a level adjustment circuit (5).
) and the voltage signal supplied from the variable resistor (7) are superimposed and supplied to the current control terminal (6a) of the recording current control circuit (6).

The recording current control circuit (6) outputs a luminance signal modulated for recording, and supplies it to the negative mixed signal input terminal of the mixer (8).

The other configuration of the recording apparatus of this example is similar to that of the recording apparatus of FIG. 3 shown as a conventional example.

By configuring the recording device of this example as described above,
The amplitude of the FM-modulated luminance signal is controlled by the recording current control circuit (6) according to the level of the luminance signal output by the pre-emphasis circuit (2). That is, the current control terminal (
6a) is supplied with a voltage signal in which a recording current control signal set by the resistor (7) and an amplitude control signal corresponding to the level of the luminance signal output by the level adjustment circuit (5) are superimposed. Therefore, this recording current control circuit (6)
In this case, the recording current is controlled and the amplitude of the recording signal is also controlled. Therefore, the amplitude-modulated luminance signal is recorded on the magnetic tape from the magnetic head (11), and the sidebands of the video signal obtained by playing back this magnetic tape are strengthened, improving the image quality during playback. There is profit.

In this example, since this amplitude modulation is performed by the recording current control circuit (6), there is no need for an amplitude modulation circuit, which has the advantage of simplifying the configuration. Also,
This recording current control circuit (6) changes the amplitude by changing the current value, so instead of changing the amplitude by changing the phase of the recording signal as in conventional amplitude modulation circuits, the recording signal itself does not deteriorate. , good amplitude modulation is performed which is reproduced with good image quality.

Here, an example of a specific circuit of the recording current control circuit (6) is shown in FIG.
Input terminals (6b) and (6C) from which M-modulated luminance signals are obtained are connected to the bases of npn transistors (21) and (22), respectively, and these transistors (
21) and (22) to the output terminal (6
Connect to d) and (6e). The output terminals (6d) and (6e) are connected to the mixed signal input terminal of the mixer (8). Further, the collectors of the transistors (21) and (22) are connected to the emitters of the npn transistors (23) and (24), respectively. is connected to a power supply terminal (13) from which a predetermined power supply voltage Vcc can be obtained, and the bases of each of the transistors (23) and (24) are connected to the power supply terminal (13) via a battery (25). .

The emitters of the transistors (21) and (22) are respectively connected to npn transistors (26) and (2).
7) is connected to the collector of this transistor (2).
The emitters of each of 6) and (27) are connected to a resistor (28), respectively.
) and (29).

Also, the voltage signal output terminal (5a) of the level adjustment circuit (5)
) is connected via a capacitor (14) to the base of an npn type transistor (30) constituting the current control signal input section. Also, connect the power terminal (13) with a resistor (
15), variable resistor (7) (between fixed terminals), and resistor (1)
6), and the movable terminal of the variable resistor (7) is connected to the base of the transistor (30).

Then, connect the power supply terminal (13) to this transistor (30).
The emitter of the transistor (30) is grounded via a resistor (31), and this emitter is connected to the base of an npn transistor (32). Then, the collector of this transistor (33) is
Connected to the collector of the npn transistor (33),
The base of this transistor (33) is connected to the base of transistor (2).
6) and (27).

With this configuration, the base of the transistor (30) constituting the current control signal input section has the following characteristics:
A voltage signal is supplied in which the recording current control signal set by the variable resistor (7) and the amplitude control signal output by the level adjustment circuit (5) are superimposed, and this voltage signal causes the transistors (26) and (27 ) changes, the current value flowing through the transistors (21) and (22) changes accordingly, and the current value of the luminance signal obtained at the output terminals (6d) and (6e) changes.

Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be obtained without departing from the gist of the present invention.

〔Effect of the invention〕

According to the recording apparatus of the present invention, by performing amplitude modulation of a recording signal using a recording current control circuit, there is an advantage that good amplitude modulation can be performed with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the recording device of the present invention;
FIG. 2 is a circuit diagram showing an example of a specific circuit of the main part of FIG. 1, and FIG. 3 is a configuration diagram showing an example of a conventional recording apparatus. (6) is a recording current control circuit, and (6a) is a current control terminal. Agent Mamukai Ito
Figure 3 shows an example of a conventional recording device by Hidetaka Matsukuma

Claims (1)

[Claims] 1. A recording device having a recording current control circuit provided with a current control terminal, characterized in that an amplitude control signal is superimposed on the current control terminal.