JPH0210991A - Color signal processor - Google Patents

Abstract

PURPOSE:To decrease deterioration of the signal in the camera mode and to reduce power consumption by converting a color difference signal directly into a low frequency conversion chrominance signal without converting a color difference signal into a chrominance carrier signal in a camera incorporated type VTR. CONSTITUTION:In the camera mode of the camera incorporated type VTR, a VCO 14 is oscillated while being synchronously with a horizontal synchronizing signal from an input terminal 5. The signal is subjected to 1/8 frequency division by a frequency divider 16 to generate low frequency conversion chrominance subcarrier waves b1, b2, b3 and they are fed respectively to the 1st and 2nd balanced modulators 17, 18 and a switch 24. A modulator 17 multiplies a color difference signal at the input terminal 2 and the carrier b1, the result is fed to an adder 19 and a modulator 18 multiplex a color difference signal at an input terminal 3 and the carrier b2 and gives the result to the adder 19. Then outputs of the modulators 17, 18 are added and given to a switch 24. The switch 24 selects the output b3 of the frequency divider 16 during the burst period and an output of the adder 19 in other period. Thus, the color difference signal is converted directly into a low frequency conversion color signal.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a video tape recorder (hereinafter referred to as VTR).

) relates to a color signal processing device.

Conventional technology Conventional color signal processing devices for consumer VTRs use a method called color under, in which the carrier color signal is frequency-converted into a low frequency converted color signal, recorded, and then inversely converted and returned to the carrier color signal during playback. .

An example of a conventional color signal processing device for a VTR will be described below with reference to the drawings.

FIG. 2 is a block diagram of an example of a recording system of a color signal processing device of a conventional camera-integrated VTR. In Figure 2, 1.
2, 3, 4.5 are input terminals, 6 is an automatic gain control circuit (hereinafter referred to as ACC), 7゜1A, 1B, 26
, 27 is a balanced modulator, 8 is a low-pass filter (hereinafter referred to as
It is written as LPF. ), 9 is an output terminal, 10 is a burst gate, 11.13 is a phase comparator, 12 is a voltage controlled crystal oscillator (hereinafter referred to as vcxo), 14 is a voltage controlled oscillator (hereinafter referred to as vCO), 15 .16 is a frequency divider, 19
, 29 is an adder, and 2Q is a band pass filter (hereinafter,
It is written as BPF. ), 28 is a reference oscillator, and 30.31 is a switch. The operation of the conventional color signal processing device for a camera-integrated VTR configured as described above will be described below.

In a camera-integrated VTR, there are two modes for recording signals supplied from the camera unit (hereinafter referred to as camera mode):
There is a mode for recording signals input from the outside (hereinafter referred to as external input mode).

In the camera mode, color difference signals EB-11ER-A are supplied from input terminals 2 and 3 to balanced modulators 2θ and 27, respectively. The reference oscillator 28 generates color subcarriers 01 and 02°C3 of frequency fsc (J's is the color subcarrier frequency) and supplies them to the balanced modulators 26, 27 and the switch 30, respectively. Here, C2 is 90 degrees ahead of C1 in phase,
C3 has a phase difference of 180 degrees from C1. The balanced modulator 26 multiplies the color difference signal E, -1 by the color subcarrier C1, and the balanced modulator 28 multiplies the color difference signal "RY" by the color subcarrier C2, and the result is supplied to the adder 29. Adder 29 is a balanced modulator, which adds the outputs of the devices 26 and 2 and supplies it to the switch 30.The input terminal 4 outputs a burst gate pulse (hereinafter referred to as BG).
It is written as P. ) is supplied to the switch 30 and the burst gate 10. The switch 30 selects the color subcarrier C3 during the burst period, and selects and outputs the output of the adder 29 during periods other than the burst period. As described above, in the camera mode, the color difference signal Ell-TI"RY is converted into a carrier color signal,
The signal is supplied to the mu CCe via the switch 31.

On the other hand, in the external input mode, the carrier color signal is separated from the composite video signal input from the outside and is supplied from the input terminal 4 via the switch 31 to the mu CC 6. The output of the switch 31 has its amplitude adjusted by λGCe and is then supplied to the balanced modulator 7 and the burst gate 1Q. Purst Gate 1
A burst signal is extracted from the carrier color signal by Q, and the phase comparator 11 outputs vcx with a center frequency of fsa.

The phase is compared with the output a1 of No. 12. The oscillation frequency of vCx012 is controlled by the phase error.

In this way, the VCXO12 oscillates in phase synchronization with the burst signal.
hase Control) A/- has been configured. From the VCXO 12, a color subcarrier a1 which is phase synchronized with the burst signal and a color subcarrier a2 whose phase is delayed by 90 degrees from al are supplied to balanced modulators 17 and 18, respectively. The center frequency of the VCO 14 is Bf, which is an integral multiple of the horizontal synchronization frequency J'o. For example, in some VTRs, Bf = 8x40fH = 32Of.

Well, at 8mm'/TR, 8f = 8 x 47.25fH = 37Bf)! It is. The frequency divider 16 divides the output of VCOl 4 (@user(7)'/
T Rte is divided by 320, 8mi IJ"/'1'R is 3
(divided by 78) and supplied to the phase comparator 13.

The phase comparator 13 compares the phases of the horizontal synchronizing signal input from the input terminal 6 and the output of the frequency divider 16, and controls the oscillation frequency of vCol 4 based on the phase error. In this way, VCOl 4 is synchronized with the horizontal sync signal. The frequency divider 16 divides the output of vC014 by eight to create low-pass conversion color subcarriers b1 and b2. Here, b2 is 90 degrees ahead of bl in phase. Balanced modulator 17 multiplies al and bl and supplies the result to adder 19.

Furthermore, the balanced modulator 18 multiplies IL2 and b2 and supplies the result to the adder 19. The adder 19 receives the outputs d1. of the balanced modulators 1 and 18. d2 is added and supplied to the BPF 20. Here, al, a2. tz.

b3 respectively, &1=TLa1S1n"5C1 b1=J,, 5in(ωst+ψ) However, if ωSO"2πfSC ωs=2πfs, then d1=to 1・al・bl, −Bl, −El), sinωsct−gln( ωs
t+ψ)+cos(ωsc-ωs)-ψ)] d2=to2-a2・t)2=to2'az'bzS'n(ω5ct-)-sin(ω
st+ "9')+cos((ωsO-ω5)t-π
-ψ)] -cos ((ωsc - ωs) -ψ)]. However, K1. and 2 are the gains of the balanced modulator 17 and 18, respectively. Therefore,! =61 +d2. Here, if the circuit is balanced, that is, if K1"at "b1=2'Ea2"bz, then 6=-1・K41・Eblcos((ω8゜+ωs)
t+ψ), and the output f of the adder 19 is the angular frequency (ω8
゜+ω8) component, that is, frequency (fsc+fs)
The ingredients are only. However, if the circuit is unbalanced, that is, K+"at・Eb+ 'c K2, Ea2.Ebz, the component of the angular frequency (ω5c-(l+s), that is, the component of the frequency (fsc-fs) is an unnecessary component. remains as.

The BPF 20 removes this unnecessary component from the output of the adder 19 and supplies only the frequency (fsc+fs) component to the thousand-and-one modulator 7 as a carrier for frequency conversion. The carrier color signal supplied from Aceθ in the balanced modulator 7 is BP
Multiplied by the conversion carrier supplied from F20, LPF
At step B, unnecessary components are removed, resulting in a low frequency converted color signal, which is output from the output terminal 9.

Problems to be Solved by the Invention However, in the above-described configuration, the color difference signal is first converted into a carrier color signal in camera mode and then converted back into a low-frequency converted color signal, resulting in signal deterioration. Further, since the circuit scale becomes large and the power consumption also increases, there is a problem that it is not suitable for reducing the size and weight of a camera-integrated VTR.

In view of these points, the present invention aims to provide a color signal processing device suitable for a camera-integrated VTR, which has less signal deterioration in camera mode compared to conventional devices, has a smaller circuit scale, and consumes less power. .

Means for Solving the Problems In order to solve the above-mentioned problems, the color signal processing device of the present invention includes a first low-pass conversion color subcarrier and a first low-pass conversion color subcarrier whose phase leads the first low-pass conversion color subcarrier by 90 degrees. a low-pass conversion color subcarrier creating means for creating a second low-pass conversion color subcarrier and a third low-pass conversion color subcarrier having a phase difference of 180 degrees from the first low-pass conversion color subcarrier; a second low-pass conversion color subcarrier whose phase is delayed by 90 degrees from the first low-pass conversion color subcarrier; a first switch that selects and outputs one of the first color difference signal and the first low-pass conversion color subcarrier; a second switch that selects and outputs one of the second color difference signal and the second a≠brown color subcarrier; a first balanced modulator that multiplies the output of the first switch by the first low-pass transformed color subcarrier; a second balanced modulator that multiplies the output of the first balanced modulator and an adder that adds the output of the first balanced modulator and the output of the second balanced modulator; A third switch that selects and outputs the output of the adder during periods other than the selected burst period, and a third balanced modulator that multiplies the output of the adder and the carrier color signal, and when recording color difference signals. The first and second switches select the first and second color difference signals, respectively, and record the output of the third switch as a low-pass converted color signal. The second switch selects the first and second ≠ conversion color subcarriers, respectively, and the filter means extracts and records a low-pass conversion color signal from the output of the third balanced modulator. .

Effect of the Invention With the above-described configuration, the present invention can provide a color signal processing device in which the color difference signal is directly converted to a low-frequency conversion color signal without converting it to a carrier color signal in the camera mode, so that signal deterioration is small. In addition, it eliminates the need for a circuit for converting color difference signals into carrier color signals, and in camera mode, some circuits can be stopped, reducing power consumption, making color signals suitable for camera-integrated VTRs A processing device can be obtained.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a color signal processing device according to an embodiment of the present invention. In FIG. 1, 1.2, 3° 4.6 are input terminals, 6 is a person QC, 7, 17, 18 are 1st... Second. Third
balanced modulator, 8 is LPF, 9 is output terminal, 1o is burst gate, 11.13 is phase comparator, 12 is vcxo
, 14 is a VCO.

115.16 is a divider, 19 is an adder, and 20 is a BPF.

22, 23, 24, 25 are the first to fourth switches, and the same parts as in FIG. 2 are given the same numbers.

The operation of the color signal processing device configured as above will be described below.

In external input mode, switches 22 and 23.

26 selects the human side and performs the same operation as the conventional example shown in FIG.

- In camera mode, the first. Second. The fourth switches 22, 23, and 25 all select B. vco1
4 oscillates at a frequency Bfs in synchronization with the horizontal synchronizing signal input from the input terminal 6. The frequency divider 16 divides the output of Vlol 4 by 8 and generates the low-pass conversion color subcarrier b1. b2. Create 1.b3, respectively. Second balanced modulator 17.18
and the switch 24. Here, b2 is ahead of bl in phase shift by 9 degrees, and b3 is out of phase with bl by about 180 degrees. The first balanced modulator 17 receives the color difference signal KBi input from the input terminal 2 and the low-frequency conversion color subcarrier b1.
is multiplied and supplied to the adder 19.

On the other hand, the second balanced modulator 18 multiplies the color difference signal "R4 inputted from the input terminal 3 by the low-pass conversion color subcarrier b2 and supplies it to the adder 19. The outputs of the modulators 17 and 18 are added and supplied to the switch 24.The switch 24 selects the output b3 of the frequency divider 16 during the burst period, and selects the output of the adder 19 during the period other than the burst period. Then, the color difference signal is directly converted into a low frequency conversion color signal, which is outputted from the output terminal 9 via the switch 25.

Here, in camera mode, person CC6, burst gate 1
0, phase comparator 11, VCXO 12, third balanced modulator 7, BPF 20. The LPFB may stop its operation, which can reduce power consumption. However, compared to the conventional color signal processing device shown in Fig. 2, which first converts the color difference signal into a carrier color signal and then converts it into a low-frequency conversion color signal,
Signal degradation is small.

As described above, in this embodiment, in a VTR that converts a carrier color signal or a color difference signal into a low-band conversion color signal and records the first low-band conversion color subcarrier b1 and the first low-band conversion color subcarrier A second low-pass conversion color subcarrier b2 whose phase is 90 degrees ahead of the carrier wave and a first low-pass conversion color subcarrier b2 and 180 degrees
a frequency divider 16 for creating a third low-pass conversion color subcarrier b3 with a degree-shifted phase, and a phase of 90 degrees from the first low-pass conversion color subcarrier a1 and the first uninhibited color subcarrier; The first switch 22 creates the second subcarrier color changing subcarrier a2 and the second color difference signal -1.

and a second switch 23 that selects and outputs one of the second Takashi Kashima color subcarrier a2, and a second switch 23 that multiplies the first low-pass conversion color subcarrier b1 and the output of the first switch 22. 1 balanced modulator 1A, a second low-pass conversion color subcarrier b2, and a second low-pass conversion color subcarrier b2;
The second balanced modulator 1 multiplies the output of the switch 23 of
8, an adder 19 that adds the output of the first balanced modulator 1 and the output of the second flattened modulator 18, and selects the third low-pass conversion color subcarrier b3 during the burst period. A third switch 24 that selects and outputs the output of the adder 19 during periods other than the burst period, and a third balanced modulator that multiplies the output of the adder 19 and the carrier color signal are provided, and the color difference signal is recorded. In this case, the first and second switches 22,23 are respectively
and the second color difference signal, and the output of the third switch 24 is recorded as a low-pass conversion color signal, and when recording the carrier color signal, the first and second switches 22 and 23 are set to the first and second color difference signals, respectively. By selecting the second m-color subcarrier and extracting and recording a low-pass converted color signal from the output of the third balanced modulator 7 by L, p, ys, the color difference signal is converted into a carrier color signal in camera mode. Since the signal is directly converted to a low-frequency conversion color signal without being converted into a Power can be reduced.

Effects of the Invention As described above, the present invention provides a camera-integrated V with low signal deterioration in camera mode and low power consumption.
Excellent effects such as realizing a color signal processing device suitable for TR can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of an example of a conventional color signal processing device. 7...Third balanced modulator, 12...v
cxo, 14... vco, 1s... frequency divider, 1 end... first balanced modulator, 18...
... Second balanced modulator, 19 ... Adder, 22
...First switch, 23...Second switch, 24...Third switch, 26...
...Fourth switch. Name of agent: Patent attorney Toshio Nakao and 1 other person U.”

Claims (1)

[Claims] a first low-pass conversion color subcarrier and a second low-pass conversion color subcarrier that is 90 degrees in phase with respect to the first low-pass conversion color subcarrier and the first lowpass conversion color subcarrier; a low-pass conversion color subcarrier creating means for creating a third low-pass conversion color subcarrier having a different degree phase, and a second color subcarrier whose phase is delayed by 90 degrees from the first color subcarrier and the first color subcarrier. a first switch that selects and outputs one of a first color difference signal and the first color subcarrier; a second color difference signal and the second color subcarrier; a second switch that selects and outputs one of the color subcarriers; a first balanced modulator that multiplies the first low-pass conversion color subcarrier by the output of the first switch; a second low-pass conversion color subcarrier of 2 and the output of the second switch;
a balanced modulator, an adder for adding the output of the first balanced modulator and the output of the second balanced modulator, and a burst period selects the third low-pass conversion color subcarrier; The other components include a third switch that selects and outputs the output of the adder, and a third balanced modulator that multiplies the output of the adder by the carrier color signal. The first and second switches select the first and second color difference signals, respectively, and record the output of the third switch as a low-pass converted color signal. 2 switches select the first and second color subcarriers, respectively, and filter means extracts and records a low-pass converted color signal from the output of the third balanced modulator. .