JPH0326088A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To set the same superimposing color in recording as that in reproduction by providing a change-over switch for superimposing at the rear stage of an ACC(automatic chroma control circuit). CONSTITUTION:The change-over switches 26 which mix the chrominance signal of a SIP(superimpose) circuit in a chroma signal or a regenerating chroma signal are provided at the rear stages of the ACC 2 and 6 in a recording circuit also in a reproduction circuit. Therefore, no influence of the capacitance component (integral component) of the ACC is given on the mixture of the chroma signal or the regenerating chroma signal and the chrominance signal of the SIP circuit, and the same phase relation between the chrominance signal of the SIP circuit mixed in the chroma signal or the regenerating chroma signal and the chroma signal or the regenerating chroma signal in the recording as that in the reproduction can be set. In such a way, no difference is generated in the superimposing colors in the recording and the reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device such as a camera-integrated video recorder, and particularly relates to a magnetic recording/reproducing device such as a camera-integrated video recorder. The present invention relates to a magnetic recording/reproducing device in which no difference occurs between pose colors.

[Conventional technology]

For example, in magnetic recording and reproducing devices such as home video table recorders (hereinafter referred to as VTRs) and camera-integrated VTRs, human color video signals are converted into luminance signals (Y
The luminance signal is converted into a low carrier FM signal, and the chroma signal is
For example, as shown in FIG. 3(a) or FIG. 4(a), a burst signal is detected by an automatic chroma control circuit (hereinafter referred to as ACC) 2 after passing through a 3.58 MHz bandpass filter 1, and is set to a predetermined voltage. stabilize it. After that, since the recording band was not sufficient like a broadcasting VTR, the frequency conversion circuit (Main Conv.) 3 was used to convert 629K.
Hz (for VHS system) or 688KHz (
(in the case of the beta system) is converted into a low-pass converted color signal having a center frequency, and is outputted to a subsequent circuit such as a recording amplifier through a low-pass filter 4.

Note that the frequency conversion circuit 3 of the recording circuit is frequency controlled by a frequency control circuit 9, and the frequency is controlled by a frequency control circuit 9.
From the subcarrier oscillation circuit (VCXO) 11 whose phase is controlled by the burst signal detected via the submodulation circuit 1
2 and a 4.21 MHz bandpass filter 13 to input a subcarrier and convert the chroma signal into a low-pass conversion chrominance signal. Furthermore, during reproduction, as shown in FIGS. 3(b) and 4(b), the low-pass converted color signal output from the reproduction amplifier passes through a 629 KHz or 1.2 MHz low-pass filter 5a or 5b. , the burst signal is detected by the ACC 6 and its level is controlled to be constant, and then the frequency modulation circuit (Main Conv,) 7 returns it to a reproduced chroma signal having the original color carrier frequency, which is 3.58 MHz.
It passes through a bandpass filter 8 and is output as a video signal. As shown in FIG. 4(b), the frequency modulation circuit 7 inputs the subcarrier output from the subcarrier oscillation circuit (XO) 15 to a submodulation circuit 18 and a 4.21 MHz bandpass filter 19 to lower the subcarrier. The subcarrier output from the WIwL transmission oscillation circuit (XO) 15, which is configured to demodulate the gamut-converted color signal into a reproduced chroma signal, is frequency-controlled by a frequency control circuit 4, and the phase of this subcarrier is detected. The sub modulation circuit 18 modulates the output of the voltage controlled oscillation circuit 17 whose phase is controlled by the phase detection circuit 16. The superimpose processing circuit (hereinafter referred to as the SIP circuit) transmits the subcarrier from the subcarrier oscillation circuit (CXO) 11 during recording and from the subcarrier oscillation circuit (XO) 15 during playback through the 3.58 MHZ bandpass filter 20. a phase compensation circuit 2l that inputs and synchronizes with the horizontal synchronization signal;
A -90@ circuit 22 that delays the phase of its output by 90", a matrix circuit 23 that specifies the superimposed color, an output of the phase compensation circuit 2l, and a -90' circuit 22.
an 8-color generating circuit 24 that manually outputs the output of the 8-color generating circuit 24, controls the phases of two sub-carrier signals having different phases using a voltage signal given from the matrix circuit 23, and outputs color signals having phases corresponding to the 8 colors; It is equipped with

The color signal of the SIP circuit has a center frequency of 3.58 MHz, so when recording, it must be mixed with the chroma signal before low frequency conversion, and when playing back, it must be mixed with the reproduced chroma signal after demodulation in the frequency conversion circuit 7. be. For this reason, conventionally,
In the recording circuit, a changeover switch 26 for mixing the chroma signal and the color signal of the SIP circuit is provided in a stage further preceding the ACC 2 provided in the stage before the frequency conversion circuit 3, and in the reproduction circuit, the changeover switch 26 for mixing the chroma signal and the color signal of the SIP circuit is provided. The changeover switch 26 for mixing the signal with the ACC 6 and the frequency conversion circuit 7
It is located at a later stage. .

[Problem to be solved by the invention]

However, although there are two types of ACCs 2 and 6, one using a peak detection method and the other using a burst ACC method, the phase shift due to the internal elements (transistors and capacitors) of the ACC circuit becomes an amount that cannot be ignored due to the accumulation of these components. Therefore, a phase shift occurs between the input signal and the output signal. On the other hand, since the phase of the subcarrier of the color signal of the SIP circuit is compensated by the phase compensation circuit 21 in horizontal synchronization, the color signal has the same phase during recording and during reproduction.

Therefore, the phase relationship between the color signal of the SIP circuit mixed with the chroma signal at the stage before ACC2 and the chroma signal, and the phase relationship between the color signal of the SIP circuit and the chroma signal mixed with the reproduced chroma signal at the stage after ACC6,
The phase relationship between the color signal of the circuit and the reproduced chroma signal is different, resulting in a difference in the superimposed color between recording and reproduction.

The present invention has been made in consideration of the above circumstances,
It is an object of the present invention to provide a magnetic recording/reproducing device in which no difference occurs between the superimposed color during recording and the superimposed color during reproduction.

[Means to solve the problem]

The magnetic recording and reproducing apparatus according to the present invention includes an ACC that detects a burst signal of a chroma signal separated from a video signal and controls it to a constant level in a recording circuit, and an ACC that detects a burst signal of a chroma signal separated from a video signal and controls the chroma signal to a low frequency band in synchronization with the burst signal. A frequency conversion circuit for converting into a converted color signal is provided, and a changeover switch for mixing the color signal of the SIP circuit with the chroma signal is provided at the front stage of the frequency conversion circuit. ACC detects the burst signal and controls its level to a constant level; a frequency conversion circuit converts the low-pass converted color signal to a reproduced chroma signal having the frequency of the original chroma signal; and a chrominance signal from the SIP circuit is added to the reproduced chroma signal. This magnetic recording/reproducing device is equipped with a mixing switch and is characterized in that the superimpose switch is provided at a stage subsequent to the automatic chroma control circuit.

[For production]

As mentioned above, in the magnetic recording and reproducing apparatus of the present invention,
In both the recording circuit and the reproduction circuit, a changeover switch for mixing the chroma signal or reproduced chroma signal with the color signal of the SIP circuit is provided after the ACC.
The capacitance (integration) of ACC no longer affects the combination of the chroma signal or reproduced chroma signal and the color signal of the SIP circuit, and the color of the SrP circuit mixed with the chroma signal or reproduced chroma signal The phase relationship between the signal and the chroma signal or the reproduced chroma signal is the same during recording and during reproduction.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1(a) and 1(b).

As shown in FIG. 1(a), the recording circuit is provided with an ACC2 that inputs the input chroma signal, detects the burst signal, and stabilizes the voltage at a constant level.
A changeover switch 26 for mixing the chroma signal and the color signal of the SIP circuit is provided after the CC2.

The SIP circuit oscillates in synchronization with the burst signal detected by the ACC 2 and extracts the subcarrier from the subcarrier oscillation circuit (VX○) 11' whose frequency is controlled by the frequency control circuit 9 and this subcarrier oscillation circuit 11. 3.58MH
z bandpass filter 20, a -90° circuit 22 that delays the phase of this output by 90°, a matrix circuit 23 that specifies the superimposed color, and the output of the 3.58 MHz bandpass filter 20, -90° circuit 22 and an eight-color generation circuit 24 which inputs the output of the matrix circuit 23 and the output of the matrix circuit 23 and outputs a color signal.

Note that a circuit subsequent to the recording circuit, such as a frequency conversion circuit that converts the chroma signal into a low-frequency conversion color signal, and an EE circuit that reproduces the image on the screen of the finder are connected to the rear stage of the changeover switch 26.

On the other hand, as shown in FIG. 1(b), the reproducing circuit includes a 629 KHz low-pass filter 5a for extracting the reproduced low-pass converted color signal, and a burst signal for detecting the burst signal from the low-pass converted color signal. ACC6 stabilizes the voltage at a constant level,
a frequency conversion circuit 7 that converts the low-pass conversion color signal to a reproduced chroma signal having the same frequency as the original chroma signal, and a 3.58 MH
A z-bandpass filter 8 and a switching switch 26 for mixing the reproduced chroma signal with the chrominance signal of the SIP circuit are provided in sequence. Incidentally, both the frequency conversion circuit 7 and the 358 MHz bandpass filter 8 described above can have no phase delay.

The SEP circuit includes an oscillation circuit (XO) 15 whose frequency is controlled by a frequency control circuit 14, a 3.5 8 MHz band-pass filter 20 that extracts a color subcarrier from this oscillation circuit 15, and a phase of its output at 90 MHz. ° Delay -90
A color signal is output by inputting the output of the ° circuit 22, the matrix circuit 23 that specifies the superimposed color, the output of the 3.58MFIz bandpass filter 20, the output of the =90 ° circuit 22, and the output of the matrix circuit 23. 8-color generation circuit 24.

In this recording and reproducing apparatus, the color signal of the Stp circuit is mixed with the chroma signal or the reproduced chroma signal at the subsequent stage of ACC2 or 6 in both the recording circuit and the reproducing circuit. Therefore, the phase relationship of the color signal of the SIP circuit mixed with the chroma signal during recording with respect to the chroma signal, and the phase relationship of the color signal of the SIP circuit mixed with the reproduced chroma signal with respect to the reproduced chroma signal are determined in ACC2 or 6. It can be made equal regardless of the integral. As a result, the superimposed color during recording and the superimposed color during playback can be made the same.

Next, a magnetic recording/reproducing apparatus according to another embodiment of the present invention is
This will be explained based on FIG. 2(a) and FIG. 2(b). As shown in FIG. 2(a), the recording circuit of this magnetic recording/reproducing device includes a 3.58MH2 band-pass filter l for extracting the input chroma signal, a burst signal of the chroma signal,
ACC2 that stabilizes the voltage at a constant level, a changeover switch 26 that mixes the chroma signal with the color signal of the SIP circuit, and a frequency converter that converts the chroma signal and the color signal of the SIP circuit mixed with it into a low frequency conversion color signal. and circuit 3 in this order.

The frequency conversion circuit 3 includes a subcarrier oscillation circuit (VCXO) 1
1 and inputs the color subcarrier modulated by the sub modulation circuit 12 via the 4.21 MHz bandpass filter l3,
Based on this color subcarrier, the chroma signal and the color signal of the SIP circuit mixed therewith are configured to be converted into a low frequency conversion color signal. The frequency of the subcarrier oscillation circuit 11 is controlled by a frequency control circuit 9 consisting of a crystal oscillation circuit.
It consists of a voltage controlled oscillator circuit whose phase is controlled by a phase detection circuit IO which detects a burst signal via ACC2.

Further, the SIP circuit includes the subcarrier oscillation circuits 11 to 3.
．． A 358 MHz bandpass filter 20 that takes out a 59MHz color subcarrier, a -90@ circuit 22 that delays the output of the 3.58MHz bandpass filter 20 by 90', a matrix circuit 23 that specifies a superimposed color, and 3.5
8MI {output of z band filter 20, -90° circuit 22
and an eight-color generation circuit 24 which inputs the output of the matrix circuit 23 and the output of the matrix circuit 23 and outputs a color signal.

Furthermore, the reproducing circuit of this magnetic recording and reproducing device includes a 1.2 MHz low-pass filter for extracting the reproduced low-pass converted color signal, and a burst signal that is detected from the low-pass converted color signal and the voltage of the burst signal. ACCG, which stabilizes the
A frequency conversion circuit 7 that converts the low-pass converted color signal to a reproduced chroma signal having the same frequency as the original chroma signal, and 3.5 that extracts the reproduced chroma signal from the output of the frequency conversion circuit 7.
An 8 MHz bandpass filter 8 and a changeover switch 26 for mixing the reproduced chroma signal and the color signal of the SIP circuit are provided in this order. The frequency conversion circuit 7 includes an oscillation circuit (XO) 15 whose frequency is controlled by a frequency control circuit 14 consisting of a crystal oscillation circuit.
The color subcarrier generated by the submodulation circuit 18 and 4.21M
The low-pass converted color signal is input through a Hz bandpass filter 19 and demodulated into a reproduced chroma signal.

The sub modulation circuit 18 inputs the output of the voltage controlled oscillation circuit 17 whose phase is controlled by the phase detection circuit 16 that detects the phase of the oscillation circuit (XO) 15, a phase control signal PS, etc., and modulates the oscillation circuit (XO) 15. It is configured to convert the output to a predetermined frequency.

The SIP circuit is similar to the recording circuit S! except that the color subcarrier is extracted from the oscillation circuit (XO) 15 by a 3.58 MHz bandpass filter 20. It has the same structure as the P circuit.

In this magnetic recording and reproducing apparatus, the changeover switch 26 for mixing the chroma signal or reproduced chroma signal with the color signal of the SIP circuit is provided at the subsequent stage of the ACC 2 or 6, so that the chroma signal or reproduced chroma signal is output during recording and reproduction. The phase relationship of the STP signal mixed with the chroma signal or the reproduced chroma signal becomes the same, and the superimposed color during recording and the superimposed color during reproduction can be made the same.

〔Effect of the invention〕

As described above, in the magnetic recording and reproducing apparatus of the present invention, the superimpose changeover switch for mixing the chroma signal and the color signal of the SIP circuit during recording is provided at the subsequent stage of the ACC as in the case of reproducing.

This allows the SIP signal to be mixed into the chroma signal during recording without being affected by the ACC capacity division (integration).
The phase relationship between the O color signal and the chroma signal and the phase relationship between the color signal of the SIP circuit that is mixed into the reproduced chroma signal during reproduction and the reproduced chroma signal are the same, and the superimposed color during recording and the reproduced chroma signal are the same. This has the effect of making the superimposed color the same as the superimposed color.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, in which FIG. 1(a) is a block circuit diagram of a main part of a recording circuit in a magnetic recording and reproducing device, and FIG. 1(b) is a block circuit diagram of a main part of a recording circuit in a magnetic recording and reproducing device. FIG. 3 is a block circuit diagram of a main part of the reproducing circuit of FIG. FIG. 2 shows another embodiment of the present invention.
FIG. 2(a) is a block circuit diagram of a main part of a recording circuit in a magnetic recording and reproducing apparatus, and FIG. 2(b) is a block circuit diagram of a main part of a reproducing circuit of a magnetic recording and reproducing apparatus. FIG. 3 and FIG. 4 each show a conventional example. Fig. 3(a) is a block circuit diagram of the main part of the recording circuit in a conventional magnetic recording/reproducing apparatus, and Fig. 3(b) is a block circuit diagram of the main part of the reproducing circuit of the magnetic recording/reproducing apparatus. be. FIG. 4(a) is a block circuit diagram of the main part of the recording circuit in another conventional magnetic recording/reproducing apparatus, and FIG. 4(b) is a block circuit diagram of the main part of the reproducing circuit of the magnetic recording/reproducing apparatus. be. 2 is an ACC, 3 is a frequency conversion circuit, 6 is an ACC, 7 is a frequency conversion circuit, and 26 is a changeover switch.

Claims (1)

[Claims] 1. The recording circuit includes an automatic chroma control circuit that detects the burst signal of the chroma signal separated from the video signal and controls it to a constant level, and converts the chroma signal to a low-frequency conversion color signal in synchronization with the burst signal. At the same time, a changeover switch for mixing the color signal of the superimpose circuit with the chroma signal is provided at the front stage of the frequency conversion circuit, and a burst signal of the low frequency converted color signal reproduced by the reproduction circuit is provided. an automatic chroma control circuit that detects and controls its level to a constant level, a frequency conversion circuit that converts the low-frequency converted color signal to a reproduced chroma signal having the frequency of the original chroma signal, and a superimpose circuit on the reproduced chroma signal. What is claimed is: 1. A magnetic recording and reproducing device equipped with a changeover switch for mixing color signals, characterized in that the above-mentioned superimposition changeover switch is provided at a subsequent stage of an automatic chroma control circuit.