KR0135856B1 - Method and circuit of phase delay - Google Patents

Abstract

The present invention discloses a phase delay method and a circuit thereof in a demodulation device of an optical disc system.

According to the present invention, when it is determined that a multi-brake or NTSC signal that triggers an input FM signal is applied, the first predetermined current is multiplied, and when it is determined that a PAL signal is applied, the second predetermined current is multiplied. Including a current amount controller for controlling to be supplied to the blater, the phase of the input FM signal is delayed corresponding to the recording format by the first predetermined current amount and the second predetermined current amount so that the NTSC or PAL signal can be demodulated normally. It can be effective.

Description

Phase delay method and its circuit

1 is a view for explaining the frequency spectrum of the FM signal in the optical disk system.

2 shows different linear graphs of NTSC and PAL signals during FM demodulation.

3 is a block diagram of a reproducing apparatus of the optical disc system for the understanding of the present invention.

4 is a block diagram of the FM demodulator shown in FIG.

5A to 5C are waveform diagrams of input / output signals of the FM demodulator shown in FIG.

6 is a conceptual diagram of a phase delay circuit according to the present invention.

FIG. 7 is a detailed circuit diagram of the phase delay circuit shown in FIG.

* Explanation of symbols for main parts of the drawings

41, 42 ... First and second limits 43 ... Phase delay circuit

44. Phase detection circuit 431 ... Emitter-coupled multivibrator

432 ... Amps Controller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase delay method and a circuit thereof in an optical disc system. In particular, in an NTSC / PAL shared laser disc player, a phase is normally demodulated to properly demodulate an NTSC signal or a PAL signal in response to a difference in a recording format of an NTSC signal and a PAL signal. The present invention relates to a delayed phase delay method and a circuit thereof.

In general, an optical disc system such as a laser disc player (LDP) can record and reproduce high-density audio and video signals, and has a better random access function than a conventional audio or video signal recording device. It is attracting attention as a device for recording a large amount of information due to various advantages, such as not contacting the original plate, thereby eliminating wear of the disc and the pickup head.

This laser disk can be divided into a constant angular velocity (CAV) disk and a constant linear velocity (CLV) disk.

NTSC discs of CAV discs maintain speed of 1800rpm regardless of inner and outer periphery and 1500rpm of PAL discs.However, in case of CLV discs, the outer periphery has 1/3 speed compared to the inner periphery. Accumulate.

1 is a view for explaining the frequency spectrum of the FM signal in the optical disk system.

As shown in FIG. 1, the EFM signal includes a band carrying a digital voice signal, an analog left and right audio signal band, and a video signal band.

In the case of the NTSC, the audio subcarrier signal is frequency-modulated at 2.3 MHz and 2.8 MHz in the case of NTSC, and the audio subcarrier signal is frequency-modulated at 0.673 MHz and 1.066 MHz in the case of PAL.

In addition, when the video signal band is NTSC, the peak frequency of the white signal is 9.3 MHz, the blanking level is 8.1 MHz, and the sync tip level is modulated to 7.6 MHz. Therefore, the peak-to-peak difference in frequency, that is, the main carrier deviation (Main Carrier Deviation) is 9.3 MHz-7.6 MHz = 1.7 MHz.

On the other hand, in the case of PAL, the peak frequency of the white signal is 7.9 MHz, the blanking level is 7.1 MHz, and the sync tip level is modulated at 6.76 MHz, so the main carrier deviation is 77.9 MHz-6.76 MHz = about 800 KHz.

The vertical frequency of NTSC is 60Hz, and the vertical frequency of PAL is 50HZ.

As described above, it can be seen that there is a difference in the frequency spectrum of NTSC and PAL.

Important here are the blanking level and the main carrier deviation.

The blanking level frequency of NTSC is 8.1MHz ± 50KHz, and PAL is 7.1MHz ± 35KHz. The main carrier deviation of NTSC is 1.7MHz ± 35KHz between -40IRE and 100IRE, and the main carrier deviation of PAL is 800KHz ± 20KHz between 30% and 100%.

As a result, the NTSC signal and the PAL signal have the characteristics as shown in FIG. 2, that is, the relationship between the frequency during demodulation and the FM demodulated output voltage.

Therefore, since NTSC and PAL have different recording formats from each other, the ratio of sensitivity is NTSC: PAL = 1: 1.526. Therefore, the normal sensitivity of NTSC or PAL can be reproduced only when the different sensitivity is demodulated to have a linear characteristic.

Accordingly, an object of the present invention is to control the amount of current in accordance with the NTSC / PAL control signal to have different sensitivity characteristics corresponding to the recording type when demodulating the NTSC and PAL signal recorded in different frequency forms from the optical disk The present invention provides a phase delay method for delaying phase and a circuit thereof.

In order to achieve the above object, the phase delay method according to the present invention is a method for phase delay during FM demodulation of signals of the first and second television broadcasting systems having different recording formats:

Signal determination process for determining whether the signal of the first television broadcast method or the second television broadcast method for the input FM signal: And

In the signal determination process, if it is determined that the signal of the first television broadcast method is applied, controlling the current to be supplied with the first predetermined current, and if it is determined that the signal of the second television broadcast method is applied, the second predetermined current. Including amperage control process for

The phase of the input FM signal is delayed in correspondence with the recording format by the first predetermined amount of current and the second predetermined amount of current.

In addition, the phase delay circuit according to the present invention is a circuit for disguising the first and second television broadcast signals having different recording formats during FM demodulation.

Trigger means for triggering an input FM signal; And

If it is determined that the first television broadcast signal is applied, the first predetermined current is supplied, and if it is determined that the second television broadcast signal is applied, the second predetermined current is supplied to the trigger means to delay the phase. Including a current amount control means for controlling the

The phase of the input FM signal is delayed in correspondence with the recording format by the first predetermined amount of current and the second predetermined amount of current.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the phase delay method and the circuit according to the present invention.

3 is a block diagram of a reproducing apparatus of an optical disc system for better understanding of the present invention.

Referring to FIG. 3, a high frequency signal modulated by a PWM (Pulse Width Modulation) through a preamplifier (not shown) from the optical disc enters the MTF (Modulation Transfer Function) unit 10 to compensate for the characteristics of the optical disc system.

When the output of the MTF 10 passes through the BPF 20, only the video FM signal is obtained. The FM signal is transmitted to the frequency dropout detector 30 and the FM demodulator 40. The frequency band of the BPF 20 is 8 MHz for NTSC and 7 MHz for PAL.

The frequency dropout detection unit 30 detects a case in which the frequency of the input FM signal is out of a certain frequency range due to the loss of a part of data due to the disc corrosion or the disc manufacturing error.

The FM demodulator 40 will be described in more detail in FIG. The signal passing through the FM demodulator 40 obtains a composite video base-band signal through the LPF 50 having a cutoff frequency of 5.6 MHz.

This signal is supplied to the video switch 60, and the video switch 60 is outputted from the output of the LPF 50 or from the 1H delay unit 80 depending on the presence or absence of the dropout detected by the frequency dropout detection unit 30. Select the 1H delayed signal selectively.

The video signal selected from the video switch 60 is removed through the time base correction (TBC) unit 70 to remove the GT component and then output to the synchronization signal separator 90 and the special burst suppressor 110.

In the case of PAL, the phase of the 4.43 MHz color burst signal is changed to a horizontal period of ± 135 degrees so that a specific burst signal is added to the sync tip of the video signal during modulation. A luminance signal (Y) is obtained by passing through a band reject filter (120).

The noise canceller 130 removes the noise of the luminance signal again, and the data separator 100 removes the noise of the luminance signal from the selected video line during the horizontal sync signal and the vertical sync signal separated by the sync signal separator 90. Separate inserted digital data (lead-in / out, chapter number, program status code, user's code).

The video signal from which the noise is removed is input to the mixing unit 140 that mixes OSD text data under the control of the microcomputer 150, and mixes the OSD text and finally outputs the video signal.

4 is a block diagram of the FM demodulator shown in FIG.

According to FIG. 4, the first limit 41 for limiting the FM video signal output from the BPF 20 shown in FIG. 3, and the first limit 41 for limiting the output of the first limit 41 again. A phase delay circuit for delaying the phase with respect to the output of the second limit 42 according to the second limit 42 and a control signal NT / PAL CTL for determining whether the current FM signal is an NTSC or PAL signal ( 43 and a phase difference detection circuit 44 which detects the phase difference between the output of the second limit 42 and the output of the phase delay circuit 43 and outputs it to the LPF 50 shown in FIG.

The operation of FIG. 4 will be described with reference to the waveform diagrams of FIGS. 5A to 5C.

According to FIG. 4, the FM signal output from the second limit 42 is output in the form of a square wave pulse at a period of 2π as shown in FIG. 5A.

In the phase delay circuit 43, the output of the second limit 42 (FIG. 5A) is delayed by θd as shown in FIG. 5B and output. Here,? D is varied according to the NTSC / PAL control signal.

The phase difference detection circuit 44 detects the phase difference between the output of the second limit 42 and the output of the phase delay circuit 43 as shown in FIG. 5C, and outputs the output of the phase difference detection circuit 44 by V0. Say,

V0 (DC) = 1 / T Vout dθ

= 1 / π {[V1] [2π- (θd + π)] + [V2] [θd]}, where T = π, to = 0

= 1 / π {V1 (π-θd) + V2 θd}, where V1 = 5V, V2 = 1.6V

= 1 / π {5 (π-θd) + 1.6θd}

= 5-3.4 / π θd [V] ------ (1)

to be.

On the other hand, since θd = ωΔt, ω = 2πf, and Δt = ΔVc / I × Cx, the meaning of actually changing the phase θd is the same as changing the current I.

As described above, since NTSC and PAL have different recording formats from each other, the ratio of sensitivity is NTSC: PAL = 1: 1.526. Therefore, the sensitivity should be appropriate according to the NTSC / PAL control signal.

However, the sensitivity is a function of the FM demodulated output voltage in the above formula (1), and this output voltage V0 (DC) = 5-3.4 / [pi] d.

In addition, since θd is a function of I again, the present invention was created to change the phase by changing I in the phase delay circuit 43.

Next, an embodiment of the present invention will be described.

6 is a conceptual diagram of a phase delay circuit according to the present invention.

The amount of current is controlled in accordance with the emission combining multivibration 431 and the NTSC / PAL control signal NT / PAL, which trigger the square wave FM signal output from the second limit 42 of FIG. And a current amount controller 432 for delaying the phase of the output of the emission coupled multivibration 431.

In addition, the current amount controller 432 includes an NTSC current source 433 for supplying current to the emission coupled multivibration 431 for an NTSC signal, and an emission coupled multivibration for a PAL signal. A PAL current source 434 for supplying current to the tee 431, a control switch 435 for switching the NTSC current source 433 and the PAL current source 434.

FIG. 7 is a detailed circuit diagram of the phase delay circuit shown in FIG. 6. The configuration is as follows.

The emission coupling multivibration 431 has a base connected to a first input terminal IN1, a collection connected to a first transistor Q1 connected to a Vcc terminal through a resistor R1, and a base formed of a first transistor Q1. The second transistor Q2 is connected to the second input terminal IN2, the collector is connected to the resistor R2 connected to the Vcc terminal, and the base is connected to the third input terminal IN3. The third transistor Q3 connected to the emitter of the transistor Q1, the base is connected to the fourth input terminal IN4, the collection is connected to the emitter of the second transistor Q2, Emiti is the fourth transistor Q4 connected to the third transistor Q3, and the first transistor Q1 and the second transistor Q2. It consists of the capacitor | condenser C connected between them.

The current amount controller 432 has a base connected via a resistor R7, a collective connected to an emitter of a fourth transistor Q4, and an emitter connected to a resistor R8 to a grounded seventh transistor. The stirrer Q7 and the base are connected to the base of the seventh transistor Q7, the collective is connected to the Vcc terminal through the variable resistor R5, and the emity is grounded through the resistor R6. The fifth transistor Q5 and the base are connected to the collector of the fifth transistor Q5, the collector is connected to the Vcc terminal, and the emitter is connected to the base of the fifth transistor Q5. The six transistors Q6 and the source connected to the substrate are connected to the Vcc terminal, the gate is connected to the drain of the first PMOS Q8, and the base is connected to the base of the seventh transistor Q7. The collector is connected to the drain of the first PMOS Q8, the emitter is connected to the ninth transistor Q9 grounded through the resistor R9, the source connected to the substrate is connected to the Vcc terminal, and the gate isThe second PMOS Q10 connected to the gate of the first PMOS Q8, the base is grounded through the resistor R11, the collection is connected to the drain of the second PMOS Q10, and the emitter is connected to the resistor R10. The eleventh transistor Q11 grounded through the base and the base are connected to the collection of the eleventh transistor Q11, the collection is connected to the Vcc terminal, and the emitter is connected to the eleventh transistor Q11. The twelfth transistor Q12 connected to the base, the base is connected to the ethity of the twelfth transistor Q12, and the collection is connected to the collection of the seventh transistor Q7, The thirteenth transistor Q13 grounded through the resistor R12 and the base are connected to the NTSC / PAL control signal NT / PAL CTL input terminal through the resistor R13, and the collective is the twelfth transistor. It is connected to the base of (Q12), and the essence consists of the 14th transistor Q14 connected.

Next, the operation of FIG. 7 will be described.

Referring to FIG. 7, first, the reference current Iref flowing through the variable resistor R5 is

Reference current (Iref) =

to be. The current i _a flowing in the transistor Q7 is

ia = Iref x (R6 / R8).

The current io and current id flowing in the first PMOS Q8 and the second PMOS Q9 are

io = Iref × (R6 / R9) = id

The current ib flowing through the transistor (Q13)

ib-Id x (R10 / R12).

Therefore, the current (isource) flowing in the emission coupling multivibration 431 is

isource = ia + ib

to be.

When the signal applied from the NTSC / PAL control signal is an NTSCL signal, that is, when the row control signal is applied

Q13 goes off,

isource = ia + ib and here is about 1300 uA.

In the case of PAL, since the high control signal is applied, the transistor Q13 is turned on and isource = ia, which is about 800uA.

Therefore, the present invention is used for LDP for demodulating NTSC or PAL modulated recording signals. It can also be applied to a system for demodulating FM recording signals of any given format.

As described above, the phase delay method and the circuit according to the present invention have different recording formats by controlling the amount of current according to the NTSC signal or the PAL signal when demodulating in response to the difference between the recording formats of the NTSC signal and the PAL signal. There is an effect that can be demodulated for two signals having a.

Claims (4)

In a method for phase-delaying a FM demodulation signal of a first and second television broadcasting system having different recording formats: Signal determination process for determining whether the signal of the first television broadcast method or the second television broadcast method for the input FM signal: And If it is determined that the signal of the first television broadcast method is applied in the signal determination process, controlling the current to be supplied with the first predetermined current and the second predetermined current when the signal of the second television broadcast method is applied. Including amperage control process for And wherein the phase of the input FM signal is delayed corresponding to the recording format by the first predetermined amount of current and the second predetermined amount of current. In a circuit for phase-delaying a FM demodulation signal of a first and a second television broadcasting system having different recording formats: Trigger means for triggering an input FM signal; And If it is determined that the first television broadcast signal is applied, the first predetermined current is supplied, and if it is determined that the second television broadcast signal is applied, the second predetermined current is supplied to the trigger means to delay the phase. Including a current amount control means for controlling the And the phase of the input FM signal is delayed in correspondence with the recording format by the first predetermined amount of current and the second predetermined amount of current. Limit means for limiting the applied FM signal into a square wave signal; A FM demodulation device for an optical disc system having a phase delay circuit for phase-delaying a signal output from the limit means, and a phase detection circuit for detecting a phase difference from an output of the limit means and an output of the phase delay circuit. The phase delay circuit Trigger means coupled to the limit means for triggering the square wave signal; And And a current amount control means for controlling the current amount of the trigger means according to the type of the FM signal applied. The method of claim 3, wherein the current amount control means Current source for NTSC signal: Current source for PAL signal; And And a selection means for selecting the current source for the NTSC signal as the current source for the NTSC signal and applying the current source for the PAL signal to the trigger means when the NTSC signal is applied.