JPH06141340A - Video signal recording processing circuit for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To automatically change a recording level of a video signal in accordance with each mode with a simple circuit configuration by generating a control voltage in accordance with a mode signal or a magnetic recording medium speed signal and adjusting the recording level in accordance with the control voltage. CONSTITUTION:An inputted video signal is separated into a luminance signal (Y signal) and a chroma signal (C signal) at a Y/C separator circuit 1. The separated Y signal is frequency-modulated by a Y signal processing circuit 2 and inputted to a Y signal recording level adjustment circuit 11. The level adjustment circuit 11 has a circuit (VCA circuit) varied in accordance with a control voltage and the level of the inputted FM signal is adjusted via the VCA circuit. On the other hand, the C signal is subject to low frequency conversion by a C signal processing circuit 5 and the level is adjusted by a level adjustment circuit 12 similarly to the case with the level adjustment circuit 11. Then a control signal in accordance with each mode and each tape speed is inputted to a microcomputer 14 and the control voltage inputted to the VCA circuit is revised accordingly to adjust the recording level optimizingly.

Description

Detailed Description of the Invention

[0001]

This invention relates to a luminance signal (Y signal).
And the recording level of the color signal (C signal) in each mode (S-VH
(S-SP, EP, VHS-SP, EP, etc.) The present invention relates to a video signal recording processing circuit of a magnetic recording / reproducing apparatus which is automatically switched according to the type.

[0002]

2. Description of the Related Art FIG. 2 shows a video signal processing circuit of a conventional VTR and a video camera, 1 is a Y / C separation circuit, 2 is a Y signal processing circuit, and 3 is a Y signal recording level (REC-Y).
Switching circuit, 4 Y signal recording level adjusting circuit, 5 C signal processing circuit, 6 C signal recording level (REC-C) switching circuit, 7 C signal recording level adjusting circuit, 8 mix circuit, 9 magnetic A switching amplification (HEAD REC) circuit 10 for switching each head for recording and for amplifying a current is a head for performing tape recording by performing electromagnetic conversion.

Next, the operation will be described. The input video signal is separated into a Y signal and a C signal by the Y / C separation circuit 1. In the case of a video camera without an external input terminal, the subsequent operations are common. The separated Y signal is FM converted by the Y signal processing circuit 2 and input to the Y signal recording level switching circuit 3.

FIG. 3 shows the circuit configuration of the Y signal recording level switching circuit 3, in which the input FM signal is switched between S-VHS and VHS levels by the resistors R ₁ and R ₂ and the transistor Q ₁ . Level switching according to the tape speed is performed by ₁ , R ₃ and the transistor Q ₂ .
Further, when the emitters of the transistors Q ₁ and Q ₂ are simultaneously grounded (that is, when the bases of the transistors Q ₁ and Q ₂ are 3 to 5 V at the same time), the parallel resistance components of the resistors R _{1 to} R ₃ are used. Level switching is performed.

The signal whose level has been switched as described above has its DC component cut by the capacitor C ₁ , and then the resistor R
_The bias is superposed by R ₄ and R ₅ , and the transistor Q ₃
It is input to the base of and the impedance is converted. This signal is output from the emitter of the transistor Q _3, after being cut DC component by the capacitor C _2, of FIG. 2 Y
It is adjusted by the signal recording level adjusting circuit 4.

On the other hand, the separated C signal is low-frequency converted by the C signal processing circuit 5 and input to the C signal recording level switching circuit 6. In the circuit 5, level switching and impedance conversion are performed similarly to the Y signal recording level switching circuit 3, and adjustment is performed by the C signal recording level adjusting circuit 7.
After the Y and C signals output from the adjusting circuits 4 and 7 are mixed by the mix circuit 8, the switching amplification circuit 9 performs current amplification and switching of each head, and the head 10 performs electromagnetic conversion of the signal to perform tape conversion. Magnetically record.

[0007]

The conventional VTR and video camera are constructed as described above, and the Y signal and the C signal are used.
A complicated external circuit as shown in FIG. 3 is required for switching the signal recording level.

The present invention has been made to solve the above problems, and a magnetic recording / reproducing apparatus capable of automatically switching the recording level of a video signal according to each mode with a simple circuit configuration. The purpose is to obtain a video signal recording and processing circuit.

[0009]

A video signal recording processing circuit of a magnetic recording / reproducing apparatus according to the present invention comprises a recording level adjusting circuit for adjusting the recording levels of a luminance signal and a chrominance signal in accordance with a control voltage, and a mode. A signal and a tape speed signal are input, and a control means for varying the control voltage of the recording level adjusting circuit in accordance with the signal is provided.

[0010]

According to the present invention, the luminance signal and the color signal are input to the recording level adjusting circuit, and the recording level is adjusted in accordance with the control voltage input to the circuit, and the control voltage is used as the mode signal and the tape speed signal. Accordingly, it is controlled by the control means.

[0011]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. 11
Is a Y signal recording level adjusting circuit, 12 is a C signal recording level adjusting circuit, 13 is a D / A converter, 14 is a microcomputer for switching data in each mode, and 15 is an E ² PROM. Other configurations are the same as the conventional one.

Next, the operation will be described. First, the input video signal is converted into a Y signal and a C signal by the Y / C separation circuit 1.
Separated into signals. In the case of a video camera without an external input terminal, the subsequent operations are common. The separated Y signal is FM converted by the Y signal processing circuit 2 and input to the Y signal recording level adjusting circuit 11. The Y signal recording level adjusting circuit 11 changes the level of the input signal to a DC voltage (control voltage).
Has a circuit (VCA circuit) that varies according to the input signal, and the level of the input FM signal is adjusted via this VCA circuit. The DC voltage input to the VCA circuit is generated by the D / A converter 13 and the microcomputer 14, and this DC voltage value is stored in the E ² PROM 15 connected to the microcomputer 14. Here, a control signal corresponding to each mode and tape speed (S-VHS / VHS, SP / EP, etc.) is input to the microcomputer 14, and the DC voltage input to the VCA circuit is changed in accordance with the control signal. The recording level of the Y signal is optimally adjusted depending on the mode or tape speed.

On the other hand, the separated C signal is low-frequency converted by the C signal processing circuit 5, and the C signal recording level adjusting circuit 12
Entered in. The adjusting circuit 12 also has an adjusting circuit 11
The level of the input signal is adjusted in the same manner as in 1.
The outputs of 1 and 12 are combined by the mix circuit 8, the switching amplifier circuit 9 amplifies the switching of each head and the current flowing through the head according to the combined signal, and the head 10 electromagnetically converts the output of the switching amplifier circuit 9. , Magnetically record signals on tape.

Second Embodiment In the first embodiment, the optimum recording level is set according to each mode or tape speed. However, if the generated DC voltage is changed according to the type of tape used for the control contents of the microcomputer 14, The optimum recording level can be controlled according to the type of tape used.

[0015]

As described above, according to the present invention, the control voltage is generated according to the mode signal or the magnetic recording medium speed signal, and the recording level is adjusted according to the control voltage. It is not necessary to provide a complicated external circuit in, and level adjustment can be performed with a simple circuit.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a video signal recording processing circuit of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a configuration diagram of a video signal recording processing circuit of a conventional magnetic recording / reproducing apparatus.

FIG. 3 is a circuit diagram of a conventional recording level switching circuit.

[Explanation of symbols]

 2 Y signal processing circuit 5 C signal processing circuit 8 mix circuit 9 switching amplifier circuit 10 heads 11 and 12 recording level adjusting circuit 14 microcomputer

Claims (1)

[Claims] 1. A luminance signal processing circuit for FM-converting a luminance signal of an input video signal, a color signal processing circuit for low-pass converting a color signal of the input video signal, and a recording level of the FM-converted luminance signal. Luminance signal recording level adjusting circuit for adjusting the recording level of the low-frequency converted color signal according to the control voltage, a mode signal or a magnetic recording medium speed signal Control means for varying the control voltage in response to the input, a synthesizing circuit for synthesizing the outputs of the recording level adjusting circuits, and a switching for performing head switching and head current amplification according to the output of the synthesizing circuit. A video signal recording / processing circuit for a magnetic recording / reproducing apparatus, comprising: an amplifier circuit; and a head for magnetically recording on a magnetic recording medium according to the output of the switching amplifier circuit.