JPS60249487A - Video signal processing method - Google Patents

Abstract

PURPOSE:To prevent the disturbance of pictures at a reproducing time without requiring another switching pulse generating means by using the switching pulse of rotary magnetic heads to generate a pulse which inhibits noise elimination of a vertical synchronizing signal part. CONSTITUTION:The switching pulse from a pulse generating means 3 is differentiated by a differentiating circuit 6, and the negative pulse is cut by a diode 12 to take out only the rise pulse. The fall pulse is taken out by a differentiating circuit 5 and a diode 11 similarly, and they are synthesized and are given to the CL terminal of a flip-flop 21. A DC voltage VCC is applied to the D terminal of the flip-flop 21, and a pulse voltage dependent upon the time constant determined by a resistance 17, a diode 13, and an integrating circuit 18 is outputted to the Q terminal when the pulse voltage is applied to the CL terminal. This outputted pulse voltage is outputted for every head switching and is applied to a noise eliminating circuit having line correlations, and the noise eliminating circuit is unoperated during this time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a video signal processing method in a magnetic recording/reproducing device.

(b) ``rNHK Home Video Technology to Improve S/N in Conventional Magnetic Recording and Playback Devices'' (published by Japan Broadcasting Publishing Association)
A line correlation noise removal circuit that utilizes the line correlation of a video signal as shown in FIG. 8-7 on page 104 of , a contour correction circuit that emphasizes the contour of an image, and the like are used.

However, during playback, in the former case, the video signal is
(H is one period of the horizontal synchronization signal) It is very effective if there is a correlation, but the vertical synchronization signal period of the video signal contains an In cut pulse in the front sync tip part due to the interlace relationship. 1H correlation disappears, and even if a line correlation noise removal circuit is used during the vertical synchronization signal period, the vertical synchronization signal is disturbed, and the interlacing of the television screen may not be performed. In addition, in the case of teletext broadcasting, transmission is performed using a pulse code etc. on the back porch of the vertical synchronization signal period, so there is no IH line correlation, and if a line correlation noise removal circuit is used, teletext broadcasting will not be reproduced. there were.

In the latter case, there is a risk that the transmission of pulse codes and the like to the back porch during the vertical synchronization signal period during teletext broadcasting may be disrupted, resulting in drawbacks such as malfunctions during decoding.

(c) Object of the Invention The present invention eliminates the above-mentioned drawbacks, and an object thereof is to provide a video signal processing method that prevents disturbances in the vertical synchronization signal period of a video signal.

B) Structure of the Invention The present invention provides a magnetic recording and reproducing apparatus in which a switching pulse for switching a rotating magnetic head for recording and reproducing video signals is generated by a pulse generating means, and the rising and falling edges of the switching pulse, or the Creating a pulse with a predetermined width by a pulse creating means from a position delayed by a predetermined time from the rising and falling edges of the switching pulse, inputting the pulse with the predetermined width to the control unit,
The image processing circuit for the video signal having a line correlation is rendered inoperable during the entire period or only a part of the period of the vertical synchronization signal portion of the video signal by a control output having the same width and the same timing as the pulse of the predetermined width. This is a video signal processing method.

(e) Examples The details of the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1 shows an implementation circuit for carrying out the video signal processing method of the present invention, and FIG.
G) and (G) are the glue in Figure 1, a, b, c, CL, respectively.
, Q, Q, and R waveform diagrams.

To explain the drawing number, circuit configuration, and circuit operation of FIG. 1, (11 is a power supply terminal, (2) is a power supply line, (3) is a pulse generating means, (4) is a PNP type transistor, (
5) t61 is a differential circuit consisting of a capacitor (force and resistance (8), a capacitor (9) and a resistance (10), αυ
(12 (131&! diode, a Tsukuda!19uen is a resistor, 鞞 is an integrator circuit consisting of a resistor (11 and a capacitor), Cυ is a delay-type 7-linopflop as a pulse generation means, (2 bottles is a control unit, ) is a noise removal circuit as one circuit of an image processing circuit having line correlation, and connects the pulse generating means (3) and the transistor (4) pace via a resistor α4), and also connects its emitter to the power supply terminal ( 1) is connected to the power supply line (2), and the collector is grounded via the resistor a as its load, and the differential circuit (connected to the capacitor (power) which is a component of the clause, and the anode of the diode aυ is connected to the capacitor (7) and resistor (8) which are the constituent elements of the differential circuit, and its cathode is grounded through the resistor (161) and connected to the CL terminal of the flip-flop Qυ and the cathode of the diode az, Pulse generating means (3) and diode (
1′! A differential circuit is inserted between the anodes of J. Then, the D terminal of the flip-flop Q1) and the power supply line (2
), connect the Q and Q terminals to the input side of the control unit (22), connect the output side of the control unit (c) to the noise removal circuit (c), and connect the resistor ( 19 and a diode 0 are connected in parallel, and a resistor (1η concave) is connected in series and connected to R and Q terminals at one end of each.

First, in the magnetic recording/reproducing device, the power supply voltage vcc shown in Figure 2 (a) K is input to the power supply terminal (IK), and during recording, the switching pulse as shown in Figure 2 (b) is generated from the pulse generating means (3) K. Accordingly, a plurality of rotating magnetic heads are sequentially switched to record video signals on a magnetic tape.

Next, during reproduction, the switching pulse shown in FIG. 2(b) is similarly generated from the pulse generating means (3)K, and the plurality of rotating magnetic heads are sequentially switched to read the video signal from the magnetic tape. Here, the rising edge of this switching pulse is the differential circuit IJ.
6, and the negative polarity pulse of the differential waveform is canted by the diode α2, so that the waveform of C becomes the waveform shown in FIG. 2). Also, when the switching pulse falls, the resistance 04)
The base potential of the transistor (4) decreases through the transistor (4), turning on the transistor (4), and the waveform at its collector becomes a pulse that is an inversion of the switching pulse, that is, the rising edge of the inversion pulse is differentiated by the differentiator f5) Ic, The negative polarity pulse of the differential waveform is canted by the diode Uυ, and the waveform of b whose potential is lowered by the resistor (161) becomes the waveform shown in FIG.
The waveform applied to the CL (clock) terminal of ) is shown in Figure 2 (
The waveform of Fig. 2 (e) is obtained by combining the waveforms of (c) and (c).

The D (take) terminal of the flip-flop Qυ is shown in Figure 2 (
b) A power supply voltage Vcc indicating K is applied, and here C
When the pulse voltage shown in Figure 2 (e) is applied to the L terminal, a rising high-level voltage is about to be output from the Q terminal, but at the same time when the output voltage rises from the Q terminal, K
A diode (13,
A reset voltage is applied that gradually rises according to the time constant determined by the resistor (17) and the integrating circuit U. When it rises to the threshold voltage shown by the broken line, the output voltage from the Q terminal is set, and then the reset voltage is applied. The voltage gradually falls according to the time constant (that is, the Q terminal outputs a so-called positive pulse voltage that rises and falls with the pulse width being the rise time of the reset voltage determined by the above-mentioned time constant). Also, from the Q terminal, a so-called negative polarity pulse voltage, which is an inversion of the output voltage from the Q terminal and which falls and rises, is output.

Pulse generating means (3) generates a pulse voltage of this Q or Q terminal.
It is outputted at the rising and falling edges of the switching pulse of 7 to the rotating magnetism generated by the 7D switching pulse, and is inputted to the control section (company), and the control output causes a noise removal circuit (
In order to prevent noise removal from the vertical synchronization signal part included in the switching pulse width and disturbing the vertical synchronization signal part, Q or ゛ is a noise removal circuit corresponding to the pulse width output from the Q terminal (c).
The image processing circuits, etc., are rendered inactive.

Also, if the noise removal circuit (c) etc. is made inactive only for a part of the period of the vertical synchronization signal section, it depends on which period of the vertical synchronization signal section the noise removal circuit (c) etc. is made inactive. The output timing and pulse width of the pulse voltage output from Q or the Q terminal must be considered. Therefore, when the output timing of the former pulse is varied, an integrating circuit (not shown) is provided after the pulse generating means (3) to integrate the switching pulses generated by the pulse generating means (3). A switching pulse formed by setting a predetermined level of this integral waveform as a threshold potential is generated by the pulse generating means (3
), the pulse is delayed by the time from the rise of the switching pulse to the threshold potential of the integral waveform. From this, 7 Lip Frog C! ! The pulse voltage supplied to the CL terminal of J) is also delayed by this time, and Q
And the output timing of the pulse voltage output from the Q terminal is varied.

In addition, when the latter pulse width is varied, the entire period of the vertical synchronization signal section (which may include a part of the video signal before and after the vertical synchronization signal section), including the case where the noise removal circuit (c) etc. is inactive. Q and Q The pulse width output from the terminal is variable.

(f) Effects of the Invention According to the image 1# signal processing method of the present invention, noise removal in the vertical synchronization signal section is performed by an image processing circuit such as a noise removal circuit having a C line correlation using switching pulses of a rotating magnetic head. By creating a prohibited pulse, a new means of generating a switching pulse is not required, and even if a line-correlation noise removal circuit is used during playback, disturbances in image quality during playback can be prevented, and teletext broadcasting is prevented. This provides advantages such as being able to reliably reproduce the data.

[Brief explanation of the drawing]

FIG. 1 is an implementation circuit diagram for implementing the video signal processing method of the present invention, and FIG. 2 is a waveform diagram at each point in FIG. 1. Explanation of main drawing numbers (3)... Pulse generation means, (2+)... Flip-flop, @... Control section, (To)... Noise removal circuit. Applicant Sanyo Electric Co., Ltd. and one other agent Patent attorney Shizuo Sano

Claims (1)

[Claims] (1) In a magnetic recording and reproducing device, a pulse generating means generates a switching pulse for switching a rotating magnetic head for recording and reproducing video signals, and the rising and falling edges of the switching pulse, or the rising and falling edges of the switching pulse, A pulse with a predetermined width is created by a pulse creating means from a position delayed by a predetermined time from the falling edge, the pulse with the predetermined width is inputted to the control section, and the control output is performed with the same width and the same timing as the predetermined width + 7) pulse. A video signal processing method, characterized in that an image processing circuit for the video signal having a line correlation is made inactive during the entire period or only a part of the period of a vertical synchronization signal portion of the video signal.