KR870002480Y1 - Herical scanning system - Google Patents

Abstract

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Description

Variable Slow-Speed Regeneration Circuit in VTR with Helical Scanning Method

1 is a general operation principle diagram of a conventional variable low speed regeneration circuit.

2 is an opening diagram of the present invention.

3 is a circuit diagram of the subject innovation.

4 is an input and output waveform diagram of each part to understand the operation principle of the present invention.

Fig. 5 (a) is a reference diagram for examining the state of an image reproduced on a TV receiver which is a monitor and a state in which a channel for one frame is viewed with an oscilloscope when the tape is played at a normal speed. Figure 5 (b) is a reference diagram to find out the above state in the tape stop state. 5 (c) is a reference diagram to find out the above state when the tape is played back at variable low speed.

* Explanation of symbols for main parts of the drawings

HSP: 30Hz switching pulse detected from video head 1: Low speed setting part

CTP: 30Hz control pulse detected from tape 1: Tape start phase control unit

3: motor driving pulse generator 4: tape stop phase controller

5: Motor drive pulse shaping part 6: Motor stop part

MDA ₁ , MDA ₂ : Motor Drive Amplifier CM: Capstan Motor

The present invention relates to a circuit in which a tape advance speed is varied from 1/30 to 1/3 at low speed in a two-head helical canning type video tape recorder (VTR), but image noise does not occur.

The two-head helical canning type VTR to which the present invention is applied has two image heads attached to the upper drum of the rotating body at an interval of 180 ° so that one image head (hereinafter referred to as Ch-1 head) is one field. The track for (Field) is tracked (hereinafter referred to as Ch-1 track), and then another video head (hereinafter referred to as Ch-2 head) is track for one field (hereinafter referred to as Ch-2 track). Screening to reproduce an image of one frame with one rotation of the drum, and at normal speed, the tape running speed should be low (VHS type 33,35mm / sec) and the head drum The relative speed (VHS type 5.8 m / sec) between the tape and the image head is increased at high speed (1800 rpm) with respect to the tape traveling speed.

At this time, the drum is inclined at an arbitrary angle with respect to the tape advancing direction.

Here, if the Ch-1 head is slightly out of the Ch-1 track and the Ch-2 track is scanned while the Ch-1 head and the Ch-2 head of the two heads each play one track, the crosstalk of the image is performed. Since cross talk is caused, the azimuth recording method of recording the cap of the video head to have an arbitrary angle opposite to the vertical direction of the video track is applied to eliminate the cross talk phenomenon. do.

However, in the conventional two-head helical scanning type VTR, the conventional means for obtaining a low-speed screen as shown in the first diagram, the phase control pulse (VP) and the capstan motor obtained from the capstan motor phase control system of the VTR Speed control pulses (VP) obtained from the speed control system are added to the synthesizer, and a variable resistor (VR ') is placed at the output terminal to reduce the speed of the capstan motor (CM). . Where CP is the capstan motor's cutoff control pulse and MDA ₁ and MDA ₂ are the capstan motor drive amplifiers.

However, this method is inevitable noise bar as shown in Fig. 5 (c) when the screen recorded at the normal speed (drum speed 1800rpm capstan speed 33,35mm / sec) drops only the capstan motor speed. Is generated and is not preferred.

In other words, specifically for this reason, as shown in (Table 1), tracks recorded at normal speed (where V _t is tape in (Table 1))

TABLE 1

Where V _t is the tape speed and direction D _t is the drum speed and direction H _t is the scanning direction of the image head.

In this case, if the scanning or recording direction of the image head is assumed to be H _t ), no image noise appears as shown in Fig. 5 (a), but the tape is slowed down by V _t . In this case, the direction of H _t 'is inclined from the normal speed H _t direction, and the track is recorded at the normal speed. Thus, as shown in B of FIG. 5 (c), two image heads are separated from the jet racks and connected to adjacent tracks. By detecting the video signal, as in CB of Fig. 5 (c), the oscilloscope shows that the signal obtained from each adjacent track constitutes one frame, which is the noise on the monitor as in C of Fig. 5 (c). Bar (Nb) will be generated a lot.

The present invention has been invented in view of the above, which uses a 30 Hz switching pulse (HSP) taken from the head drum and a control pulse (CTP) recorded together when recording an image signal on the tape. The screen is played by advancing the frame, but the same track is repeatedly scanned for n frame periods so that the low-speed moving speed of the screen can be varied by 1 / n + 1 times, so that no image noise occurs at all.

This will be described in detail below.

2 is an opening diagram of the present invention, which has a low speed setting unit 1 for dispensing the switching pulse CTP extracted from the head drum at 1 / n + 1 times speed, and the output of the low speed setting unit 1 is tape It is connected to one end of the generating section 3 which generates the capstan motor driving pulse through the tape start phase control section 2 to match the starting point, and the stop point of the tape using the control pulse CTP released on the tape. And a tape stop phase control section (4) to match the output of the motor drive pulse generator (3), and the output of the motor drive pulse generator (3) is connected to the motor drive pulse generator (3). The driving pulse shaping unit 5 is connected to the capstan motor CM through the motor drive amplifiers MDA ₁ and MDA ₂ , but bypasses one end of the output of the motor drive amplifier MDA ₁ Capstan Motor (CM) via rotor stop (6) Once applied to the hayeoseo so connected to.

That is, the present invention of this schematic configuration is spherical through the embodiment as shown in the third diagram, wherein the low speed setting unit 1 is a monostable multi-use IC (I ₁ ) and differentiation (C ₁ , R ₀ ), low speed setting variable Integrator (R ₁ , C ₃ ) having a resistor (VR), the tape start phase control unit (2) is to adjust the start point of the scanning transistor of the inverter transistor (Q ₁ ) differentiator (C ₆ , R ₆ ) and the tape Integrators C ₉ and R ₃ with a variable resistor VR ₁ and b as shown in FIG. 4 are used to set the operating point of the monostable multi-use IC (I ₁ ). The IC (I ₁ ) is triggered at the Bootley origin, which is a falling point of), to obtain an integral wave as shown in C of FIG. 4 (where the integral waveform is set by assuming 1/3 times the speed, The low speed can be arbitrarily adjusted by adjusting the time constant of the partial separation).

Then, the integrated output of the IC (I ₁₎ an external variable resistor (VR) and a resistor connected to the (R _1), a capacitor (C ₃₎ × by the integrator 1.1 × (VR + R ₁₎ yirwojin to C ₃ The time constant value is adjusted, which is particularly important in the present invention to obtain 1 / n + 1 times the variable low speed of the screen.

It consists of a monostable multi-use IC (I ₁ ), while the tape stop phase controller 4 adjusts the variable resistor VR ₀ and the integrator C ₅ and C to adjust the timing at which the image head stops on the tape. ₄ ) and IC (I ₃ ) and inverter transistors (Q ₃ , Q ₄ ) differentiator (R ₄ , R ₅ ) and motor drive pulse generator (3) is RS flip-flop IC (I ₂ ) The motor drive pulse shaping section 5 includes the RS flip-flop IC (I ₂ ), the voltage division resistors (R ₉ , R ₁₁ ), the inverter transistor (Q ₅ ), and the differential (C ₂ , R ₂ ). The synthesizer diodes (D ₁ , D ₂ ) and the buffer transistor (Q ₂ ) are configured, and the motor stop part (6) is composed of an inverter and a buffer transistor (Q ₆ , Q ₇ , Q ₈ ).

Reference numeral T denotes a tape, H denotes a 30 Hz control pulse (CTP) detection head, and x 'denotes a code given for convenience in explaining a waveform diagram of each part.

Hereinafter, the operation and effects of the present invention will be described in detail.

That is, the inside of a 30Hz switching pulse (HSP) is a low-speed setting section (1) a capacitor (C _1), resistance integrating the IC (I ₁₎ wave obtained by this via a differentiator to the (R ₀₎ of the detection on the head drum At 4 again, a square wave is formed as shown in d of FIG.

This nine-terminal output is inverted by the inverter transistor Q ₁ of the tape start phase control unit 2 and again passes through a differentiator consisting of a capacitor C ₆ and a resistor R ₆ , thus triggering the same as f in FIG. 4. A pulse is formed and input to the six terminals of this IC (I ₁ ).

The waveform of FIG. 4 is a trigger pulse coinciding with the pulling point of the switching pulse (HSP) and having a period for imparting a random velocity, which acts as a trigger input of the IC (I ₁ ) so that the image head is tracked on a tape. Is to give a synchronization point of time to track in place.

At this time, when the video head is out of the phase position of the track of the track on the Ape by adjusting the variable resistor (VR _1), the resistance (R ₃₎ a capacitor variable resistor (VR ₁₎ of the integrator to the (C ₉₎ video The head is held in place by delaying the starting point at which the head first starts tracking in place on the tape.

This process is shown in the g, h and i waveforms of FIG. 4, and g in FIG. 4 assumes an arbitrarily delayed integral waveform, and when h is a square wave inside the IC (I ₁ ), A differentiator of capacitor C ₇ and resistor R ₈ forms a trigger pulse equal to i.

Here, the trigger pulse represents the state in which the image head is corrected to the correct position on the tape track to be initially tracked, and its delay time is assumed to be ta.

Thus, the i-waveform in FIG. 4 acts as a set input to the eight terminals of the RS flip-flop IC (I ₂ ) of the motor driving pulse generator 3.

At the same time, the 30 Hz control pulse (CTP) detected on the tape is converted into a differential pulse and acts as a base input of the inverter transistor Q ₄ of the tape stop phase control section 4 at its booting point, and its output. (K waveform in FIG. 4) acts as a trigger input to the two terminals of IC I ₃ again via the inverter transistor Q ₃ (? Waveform in FIG. 4).

Here, the control pulse (CTP) accurately stops the tape after moving the tape by one frame, so that the image head moves the magnetic track when the tape is moved by one frame after a random period. It is used for the purpose of avoiding scanning off.If the sync point of this control pulse (CTP) is not coincident, the integrator of variable resistor (VR ₀ ), resistor (R ₄ ) and capacitor (C ₅ ) is variable. The resistance is used to match the time point by the delay time t _b , and the m waveform of FIG. 4 is an integral pie obtained by arbitrarily assuming this state, which is converted into a square wave again formed inside IC (I ₃ ). do.

The n waveform of FIG. 4 thus obtained is output to the third terminal of this (IC) (I ₃ ), which is converted into a trigger pulse through a differentiation of a resistor (R ₅ ) and a capacitor (C ₄ ) (see FIG. ₄ ). 0 waveform), and is again applied to the 10 terminal of the RS flip-flop IC (I ₂ ) to act as a reset pulse at its boot trigger point.

As described above, the sync pulse for the start of the image head to be initially scanned on the tape track and the period of arbitrary double speed is determined, and the sync pulse for stopping the tape after moving by one frame is 8 of the IC (I ₂ ) for RS flip-flop. When input to each of the 10 terminals, the RS flip-flop IC I ₂ generates a square wave at the boot trigger point of each sync pulse and outputs it to 9 terminals (this process is similar to the io, p waveform of FIG. 4). same).

This square wave output is first voltage-divided (q wave of FIG. 4) by resistors R ₉ and R ₁₁ and applied to diode D ₂ of motor driving pulse shaping section 5 used for synthesizer, and at the same time After forming an inverted output (r waveform in FIG. 4) through the inverter transistor Q ₅ , it becomes a trigger pulse (s waveform in FIG. 4) again through the differentiation of the resistor R ₂ and the capacitor C ₂ . This acts as a trigger input at the boot trigger point at the six terminals of the RS flip-flop IC (I ₂ ), and is shaped into a square wave again inside thereof and applied to the input of the synthesizer diode (D ₁ ).

At this time, the width of the square wave (u of FIG. 4) is determined as an integrator by a resistor (R ₁₀ ) and a capacitor (C ₈ ), the width of which is described later, but plays an important role in determining the operating range of the capstan motor. Do it.

The square waves applied to the inputs of the diodes D ₁ and D ₂ are synthesized to obtain a waveform such as v of FIG. 4, which is again a butter transistor (Q ₂ ) and a motor drive amplifier (MDA ₁ , MDA ₂ ). Each will drive the capstan motor (CM).

Here, the v waveform of FIG. 4 forms a voltage value having a period in which the voltage value having a normal peak value for the capstan motor CM to proceed at a normal speed is abruptly halved. This operation is performed for Ch for the first field. Drive the capstan motor (CM) to track -1 track in the state of the tape where the video head proceeds at normal speed, and then halve the tape speed on the Ch-2 track for the Ch-2 head, so the capstan motor (CM) In the process of stopping the tape, the tape is correctly positioned in the jet rack (i.e., not located due to the adjacent track) so that image noise does not occur during the next one-frame tape movement and playback of the image head.

In other words, if this operation is not performed, the capstan motor (CM) will be located on the adjacent track, leaving the track of the exact position tracked by the image head again while the tape stops, so that the image noise occurs when moving the tape for the next frame. .

On the other hand, when the power is applied to drive the capstan motor CM for one frame and suddenly shuts off, an induced voltage caused by the coil component of the motor itself is induced, and thus the capstan motor CM is continuously driven and repositioned on the tape. Since the image head cannot be scanned at the correct track position when the next motion is performed because it is not located on the track and is incorrectly connected to the next track, the capstan motor is moved in the section where the tape moves as shown in the v waveform of FIG. In the period in which the driving voltage is applied to the CM, one end of the output is applied to the base of the inverter transistor Q ₆ of the motor stop ₆ , which in turn causes the buffer and inverter transistors Q ₇ and Q ₈ to be applied again. In this case, the base of the transistor (Q ₈ ) is in the OFF state at a low potential, and then the transistor Q immediately after the capstan motor driving is completed. ₈ ) is turned on to cut off the input to the capstan motor (CM) to perform the exact stop operation.

After the tape is moved by one frame, the image noise does not occur even if the two image heads scan the fixed same track position repeatedly for a set period of time, because the tape is in a stopped state. As shown in Fig. A, the Ch-1 head overlaps the Ch-1 track for one frame and the Ch-2 track, and the overall scan is performed. In this case, the Ch-1 head is Ch- due to the azimuth loss of the two-head helical canning method. Since only the signal portion of one track is detected, and the Ch-2 head detects only the signal portion of the Ch-2 track, it is similar to the signal detected by the Ch-1 head when viewed with an oscilloscope as shown in FIG. The gain is small and gradually increases to reach the normal picture, and again the gain of the Ch-2 head increases and then decreases when the signal of the Ch-2 track is detected. Monday The one-screen configuration doemeurosseo is the normal screen in a configuration state.

At this time, one noise bar (Nb) may appear on the screen seen by the TV receiver which is the monitor as shown in (C) of FIG. 4 (c), but this noise bar (Nb) may be discontinued by the vertical synchronization signal of the TV signal. It is well known that it can be easily eliminated by pushing it to the ranking part.

As described above, when a screen having a low speed variable is played back, the low speed variable has to be provided only at a very limited speed. In particular, since a noise bar, which is image noise, is generated, it is impossible to play back the normal continuous change. The reproduction speed of the low speed screen can be arbitrarily set up to 1 / n + 1 times, and in particular, since image noise does not occur at all during the reproduction of the low speed screen, there is an advantageous feature that the use value and reliability of such an article are greatly improved.

Claims (1)

A monostable multi-IC (I ₁₎ for the switching pulse (HSP) just taken out of the head drum, a differentiator (C _1, R _0), the low speed set straight branch (R _1, C ₃₎ including a variable resistor (VR) The low speed setting unit 1 is configured and connected to the integrator C ₉ and R ₃ including the variable resistor VR ₁ , the monostable multi-use IC I ₁ , the inverter transistor Q ₁ , and the differentiator ( C ₆ , R ₆ ) constitutes a tape start phase control unit 2 and is connected to the output terminal, while integrators (VR ₀ , R ₄ , C ₅ ) and differential ( A tape stop phase controller 4 is formed by C ₄ , R ₅ , inverter transistors Q ₃ and Q ₄ , and IC I ₃ , and the tape start and stop phase controllers 2 and 4 are connected. The output terminal of the motor driving pulse generator 3 is connected to the set and reset terminals of the motor driving pulse generator 3 comprising the flip-flop IC (I ₂ ). R _9, R _11), for the drive Transistor (Q _5), differentiator (C _2, R _2), the RS flip-flop IC (I ₂₎ and synthetic appointed diode (D _1, D _2), Motor driving pulse shaping by the buffer transistor (Q ₂₎ for Configure the unit (5), and connect the other output terminal to the capstan motor (CM) through the normal motor drive amplifiers (MDA ₁ , MDA ₂ ), respectively, the motor drive amplifiers (MDA ₁ , MDA ₂₎ The output of the output between the motor and the motor drive amplifier (MDA ₂ ) and the capstan motor (CM) via a motor stop (6) consisting of inverters and buffer transistors (Q ₆ ~ Q ₈ ) Variable low-speed regeneration circuit in a helical canning type VTR.