JPS58204693A - Chrominance signal processing circuit of magnetic recorder and reproducer - Google Patents

Abstract

PURPOSE:To improve the noise resistance characteristic, by constituting an APC loop at the chrominance signal recording so as to form the color killer as the phase adjusting type. CONSTITUTION:The frequency being an integer multiple of a horizontal synchronizing signal from an input terminal 10 and an oscillating frequency of the 1st voltage controlled crystal oscillating circuit VCO9 are mixed at the 1st frequency converting circuit 3, and the output of the circuit 3 and the frequency of a recording signal at a chrominance signal input terminal 1 are mixed at the 2nd frequency converting circuit 2. The output of the circuit 2 and the input from the terminal 1 are switched at the 1st switching circuit 14 in response to the recording or reproduction and applied to the 1st and the 2nd phase detecting circuits 4, 6. The frequency outputted from the circuit 14 and the oscillating frequency from the 2nd VCO13 are compared for the phase at the circuit 4, and the 2nd switching circuit 14 is switched with the result of the phase comparison and the VCO9 is controlled. Further, the automatic phase control (APC) loop is constituted at the chrominance signal recording, the color killer is formed as the phase adjusting type, allowing to attain the noise resistance characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a color signal processing circuit for a magnetic recording/reproducing apparatus (hereinafter referred to as rVTRJ).

A conventional color signal processing circuit for a VTR is shown in FIG. First, the configuration and operation of a conventional color signal processing circuit will be explained with reference to FIG.

The color signal processing circuit converts the color signal input from the color signal input terminal 1 into low w1. Alternatively, the second frequency conversion circuit 2 converts the frequency to a high frequency range, and the phase of the output of the second frequency conversion circuit 2 and the output frequency of the crystal oscillation circuit m:'ll'5 are compared and the phase difference is determined. Compare the phase of the output of the first phase detection circuit 4 and second frequency conversion circuit 2, which generate a commensurate error voltage, with the output of the crystal oscillation circuit 5, which is shifted in phase by 9o0 by passing the output of the crystal oscillation circuit 5 through the phase shift circuit 7. The second phase detection circuit 6 generates an error voltage commensurate with the phase difference, the switch circuit 8 performs ljIlrM in response to recording and reproduction, and the output error voltage of the first phase detection circuit 4 determines the oscillation frequency. It is composed of a variable voltage controlled crystal oscillation circuit 9 and the like.

Then, from the input terminal 10, a frequency nf, which is an integral multiple of the frequency of the horizontal synchronizing signal (hereinafter referred to as rr+J), is applied to the first frequency conversion circuit 3. The output of the second frequency conversion circuit 2 appears at an output terminal 11, and the detected output of the second phase detection circuit 6 appears at an output terminal 12.

Note that the frequency nfHM HZ is generally selected as n-40 for VH3 system VTRs, so in the following explanation, nfHM HZ is selected as n-40.
-40 will be explained.

・The operation of the 1.1° color signal processing circuit is as follows. First, during recording, the switch circuit 8 is opened by a signal that distinguishes between recording and reproduction (not shown), and the voltage controlled crystal oscillation circuit 9
The output error voltage from the first phase detection circuit 4 is not applied to , and the voltage controlled crystal oscillation circuit 9 operates as an oscillation circuit with an accurate fixed frequency of 3.58 MHz, which is the frequency of the color WII carrier wave, and 3. A signal with a fixed frequency of 58 MHz is applied to the first frequency conversion circuit 3 from one input terminal.

The aforementioned 40fnMH7 signal is input from the input terminal 10 of the first frequency conversion circuit 3, and the voltage! 1111JI
3.58MH2 signal from crystal oscillator circuit 9 and 40fHM
ζ3, which is the signal component of the sum with H2, 58 +40t,
) Ml-1z signal is output from the first frequency conversion circuit 3 and input to one input terminal of the second frequency conversion circuit 2. Also, since it is during recording, the second frequency conversion circuit 2 A recording conveyance color signal of 3°58 MHz is input from the signal input terminal 1, and this recording conveyance color signal is converted to (3°58+40f H) MH from the first frequency conversion circuit 3.
It is mixed with the signal of
It is output from the output terminal 11 as MI-12. At this time, the oscillation operation of the crystal oscillation circuit 5 is stopped by a signal that distinguishes between recording and reproduction (not shown), and the first phase detection circuit 4. Second phase detection circuit 6. f5 and phase shift circuit 7 also do not operate.

Next, during reproduction, the second frequency conversion circuit 2, the first phase detection circuit 4. Crystal oscillation circuit 5. Switch circuit 8.11
Voltage III III crystal oscillation circuit 9 and first frequency il
& Conversion circuit 3 is automatic phase system 1ll (hereinafter 1-AP
(referred to as CJ) loop.

In other words, the voltage controlled crystal oscillator circuit 9 is 3.58M HI
The oscillation frequency is applied to the first frequency conversion circuit 3 from one input terminal. First frequency conversion circuit 3
A signal of 40 fHMHz is applied from another input terminal 10, and these two input signals are mixed in the first frequency conversion circuit 3 to form a signal component of the sum of both signals (3
．． 58+40to) MHz, which is applied from one input terminal of the second frequency conversion circuit 2. During reproduction, the second frequency conversion circuit 2 receives data from, for example, a magnetic tape from the color signal input terminal 1, and then receives data from the chrominance signal input terminal 1.
A reproduced low frequency conversion carrier color signal (40t1±Δf)'vlHz containing a time axis fluctuation component ±ΔfMHz due to reproduction is applied, and these two signals are mixed in the second frequency conversion circuit 2, and the two signals are mixed. It is a ramie (3.58 gear Δf)
The MH2 signal is output from the output terminal. Furthermore, this output signal is applied to the first phase transverse wave circuit 4 and the second (Q-phase detection circuit 6) from one input terminal. A fixed frequency signal of 3.58M!-IZ from circuit 5 is applied, and this 3.58MHz fixed frequency signal and (3,58 fast Δ) from the second frequency conversion circuit 2 are applied.
f) An N-pressure controlled crystal generator 1□9 generates a voltage difference according to the phase difference with the MHz signal and uses a signal (not shown) to distinguish between recording and reproduction via a switch circuit 8 which is closed during reproduction. ．． □□, □6゜1-1.1□□ The oscillation circuit 9 oscillates at a frequency of MH2 (3,58±8f) according to the applied error voltage, and the first frequency conversion circuit 3
is input. Then, in the first frequency conversion circuit 3, this signal and the 40fHMH2 signal from the input terminal 10 are used in the first frequency conversion circuit 3 (3,
58+40fH±Δr) to ll-11, and is applied to the second frequency conversion circuit 2. In the second frequency conversion circuit 2, the reproduction low frequency conversion carrier color signal (40fH
±Δf)! A 3.58 MH2 signal is output from which the inter-li axis fluctuation component, which is the difference from the li-axis variation component, is removed.

As explained above, in the APC loop, the phase difference between the output signal from the second frequency conversion circuit 2 applied to the first phase detection circuit 4 and the output signal from the crystal oscillation circuit 5 is 90°. Since the output frequency of the crystal oscillation circuit 5 is a fixed frequency of 3°, :) 8 M ) (z, the output frequency of the second frequency conversion circuit 2 is 3.58 MHz, In other words, the time axis fluctuation component associated with recording and reproduction contained in the reproduction low-frequency conversion □:transformation carrier color signal input to the second frequency conversion circuit 2 is removed.

Also, while the APC loop is operating, the output signal of the first frequency gIt conversion circuit 2 and the output signal of the crystal oscillation circuit 5 are always 9
Since there is a constant phase difference of 0 degrees, the output signal of the crystal oscillation circuit 5 is changed in phase by 90 degrees via the phase shift circuit 7 and applied to the second phase detection circuit 6 from one input terminal, and the other input terminal. to the second phase transverse wave circuit 6I: When performing phase waveforming with the input output signal of the second frequency conversion circuit 2, in the case of a color signal, the two input to the second phase detection circuit 6 The difference between the signals is 1, and the signal is "low" (
or "high-") is output to the output terminal 12, and when the reproduced signal is a black and white signal, the second phase rectification circuit 6
Since the phase difference between the two signals input to is irregular, a voltage that is high j (or r (: l-, ri) with respect to the lI quasi-voltage is output to the output terminal '12. Therefore, Output to output terminal 12 [High 1. "Low J IIE can be compared with the reference voltage to apply color killer in black and white" phase detection type color with features such as excellent noise characteristics. Killer signal processing can be performed.

However, as is already clear from the above explanation, the conventional VTR color circuit does not form an APC loop during recording, so it is a phase-converting type circuit.
The problem is that it cannot be made into a complete set.

Above all, one of the strengths of this invention is to eliminate the drawbacks of conventional circuits as described above.

To put it simply, this invention is a color signal processing circuit improved so that the color killer can be of a phase detection type by configuring a 6A I-)C loop during color signal recording.

Hereinafter, this invention will be explained in more detail based on an embodiment not shown in FIG.

In the second factor, the components with the same numbers as in FIG. 1 are the same or equivalent to the conventional color signal processing circuit. A second voltage-controlled crystal oscillation circuit 1 that functions as an oscillation circuit and also functions as a fixed frequency loss crystal oscillation circuit during playback.
3 is provided in place of the crystal oscillation circuit 5 included in the conventional circuit, Hungry Yumino! ] Connected to terminal A3 and the output terminal of the second frequency conversion circuit, it is switched according to recording and playback, and the high frequency recording signal whose frequency is not converted during recording is output to the second frequency conversion circuit during playback. Transmit the frequency-converted high frequency reproduction signal to the next stage! 1, a first switching circuit, and a first phase detection circuit;
At the time of recording, the output from the two voltage-controlled crystal oscillators is transmitted to the second voltage-controlled crystal oscillator circuit to control the oscillation circuit, and during playback, the output is transmitted to the voltage-controlled crystal oscillator circuit (tη1) to control the oscillation circuit.
￥Leech, switch the transmission route according to the regeneration ￥42
The feature is that the switching circuit has been straightened. .

Next, the operation of this circuit will be explained.

At the time of recording, the first switching circuit 15 switches to the second
There is a connection LC on the E control waterfowl circuit 13 side. Therefore, the first voltage-controlled crystal oscillator circuit 9 has an ilE of 358
Works as a fixed frequency oscillation circuit for N/IH7, Part 3
．． The output signal of 58Th, 4Hz is applied to the first frequency conversion circuit 3 from one input terminal. The first frequency conversion circuit 3 receives a signal of 40rNMH2 from the input terminal 10, and is the component of the sum of these two signals (
A signal of 3.58-4-40rn>MHz is output from the first frequency conversion circuit 3 and applied to the second frequency and wave number conversion circuit 2. Then, the frequency conversion circuit 2 of 'JI2 performs recording of 40f+MH2, which is the signal component of the difference between the output signal of the first frequency conversion circuit 3 and the recording conveyance color signal of 3.58MHz applied from the color signal input terminal 1. Outputs a low frequency conversion carrier color signal.

Since this is necessary during recording, the first switching circuit 14 switches the color signal input terminal 1 by a signal that distinguishes between recording and reproduction (not shown).
'IIA and not frequency-converted to the first phase detection circuit 4 and the second phase detection circuit 6; 3.
A 58MH2 recording conveyance color signal is applied.

The first phase detection circuit 4 is simultaneously applied with the N frequency signal of the second voltage controlled crystal oscillator circuit 13 from another input electron, and the first phase detection circuit 4 receives both signals. Generates an error voltage commensurate with the phase difference, and the error voltage is before:
, 5, 7;, )j=71 t) y; shoulder
] Yo ldl a 'k W Hikari;B, Tsukasa
It was broadcasted in 313 ζ゛・ru) sword exchange jiil:
g Second Densenjin control water factory 1 rFr via 1L3
The 4u power phase of X path 13 is the 4el cape and Q of the recording conveyance color signal.
1. ``There will be a constant phase difference of 3 degrees.''

Small details, the 2nd plane phase detection circuit 4. Switching circuit 15・t
'Yo7S' The second voltage controlled crystal oscillation circuit 13 is 8PC!
The size of the jaw is 7.

Master T. No.? Since there is no fixed phase difference of 90 degrees between the output of the voltage controlled crystal oscillator circuit 13 and the recording conveyance color signal, the second electric current F, ! ': 1!1 inch - A phase detection waveform color killer is realized by changing the gC phase and applying the output signal of the crystal emission circuit 13 to the second L phase detection circuit e via the phase shift circuit 7. can do.

During playback, the first switching circuit 14 is connected to the output side of the first frequency conversion circuit 2 (411), and the second switching circuit 15 is connected to the first
Voltage controlled crystal oscillation circuit 9 [1fl! Ladle connected to the second
The voltage controlled crystal oscillator lB13 is 3°5', MH2 is a fixed frequency oscillator circuit. ′: @ij
The circuit configuration is the same as that of the color signal processing circuit of the conventional example, and the operation of t is directed toward t+.

According to this invention, a G loop is formed on the record side of color (a), .: The phase detection waveform Kanki Fu 7j is filled with ``(a quick cut of 9 stones).

4. Explanation of the PfI in Figure Ij[i Figure 1 shows the Iroike-Yumikome connection circuit of Tsunaga. The third side is a circuit diagram of a color signal processing circuit according to an example of this invention.

As shown in the figure (, '1 is the edge of the sword to Gokyu', 2 is the second frequency conversion circuit, 3 is the first frequency conversion circuit, l↓ is happy '1)
digit (9 detection circuit, 6 is the 21st) phase detection circuit, 91 introduction j voltage-J crystal optical vibration circuit, 13 yu second turtle Fil
j quartz oscillation circuit, i 4 is the 17th switching circuit, 15 is the second switching circuit g0 By the way, in the diagram C the same symbols are the same. 4-0 Agent b Nobuo -(outer'1b) ]"-:=', f+li city letter (voluntary)
"+, '+, +'l'li' l-Se111n1,
'IF 14'' J2,1, '411''
Near (Jlji 57-s 9070 g2, :
;, e, 111. h) Ro['1, Color signal processing circuit of magnetic recording and reproducing device k; Contents (1> Page 4, line 16 of the specification, “In general, n-40
J is corrected to n-40j.

(2> From page 7, line 20 to page 8, line 1 of the specification [
In the first frequency conversion circuit, "" is deleted.

(3) Set the “first frequency” on page 8, line 20 of the specification to 1.
the second frequency.

(4) Lines 1 to 12 of page 11 of the specification are amended to read as follows.

It is connected to the color scheme signal input terminal 1 and the output terminal of the second frequency conversion circuit 2, and is switched according to recording and reproduction, and the recording signal whose frequency has not been converted during recording is transmitted to the second frequency conversion circuit 2 during reproduction. A first switching circuit 14 is provided for transmitting the frequency-converted playback signal to the next stage, and the output from the first phase detection circuit 4 is transferred to the second voltage-controlled crystal oscillator circuit 13 when recording. and controls the oscillation circuit, and during playback, the first voltage-controlled crystal oscillation circuit 9
recorded to control the oscillation circuit.

A patent characterized in that a second switching circuit 15 is provided to switch the transmission path depending on whether the transmission path is amphibious or not.

Claims (1)

[Claims] A first voltage controlled oscillation circuit having a control voltage input terminal; a second voltage controlled oscillation circuit having a control voltage input terminal; a first frequency conversion circuit that generates a converted output frequency by mixing the integral multiple of the frequency and the oscillation frequency from the first voltage-controlled oscillation circuit that is input from the other input terminal; and a recording/playback signal input terminal. The frequencies of the recorded color signal and reproduced color signal are converted by mixing the converted output frequency of the first frequency conversion circuit inputted from the other input terminal with the recorded color signal and reproduced color signal inputted from the input terminal. a second frequency conversion circuit that outputs from an output terminal; and a second frequency conversion circuit that is connected to the recording/playback signal input terminal and the second frequency conversion circuit output terminal, and is switched according to recording and playback, and the frequency is converted during recording. a first recording/reproduction switching circuit that transmits a reproduction signal whose frequency has been converted by the second frequency conversion circuit to the next stage when reproducing a recorded signal whose frequency is not converted by the second frequency conversion circuit; a first phase detection circuit that compares and detects the phase of the signal transmitted through the recording/reproduction switching circuit of the second voltage-controlled oscillation circuit and the oscillation frequency from the second voltage-controlled oscillation circuit that is input from the other input terminal; The output from the first phase detection circuit is transmitted to the control voltage input terminal of the second voltage controlled oscillation circuit to control the oscillation circuit during recording, and the control voltage input to the first voltage controlled oscillation circuit during playback. The oscillation circuit is transmitted to the terminal
a second recording/playback switching circuit that switches the transmission path according to recording or playback to control J; a phase shift circuit connected to the output of the second voltage controlled oscillation circuit; a second phase detection circuit that comparatively detects the phase of the signal from the switching circuit and the oscillation frequency from the second voltage controlled oscillation circuit transmitted via the phase shift circuit and outputs a phase detection output. A color signal processing circuit for a magnetic recording and reproducing device that uses the following characteristics.