JPS60134578A - Frequency characteristic correction circuit in conversion system from field signal to frame signal - Google Patents

Abstract

PURPOSE:To prevent a level difference from being produced to a switching output signal of a switch by inserting a frequency characteristic correction circuit between a delay circuit and the switch so as to correct the frequency characteristic of the delay circuit to be flat. CONSTITUTION:One of contacts 2a, 2b is selected, and a through field signal S1 and a field signal S2 delayed by 0.5H at a delay circuit 3 are selected alternately at each vertical period by using a control signal S4 of 0.5fV (where fV is a vertical scanning frequency) applied via an input terminal 4. The frequency characteristic correction circuit 6 is inserted between the circuit 3 and the contact 2b of the switch 2 so as to correct the frequency characteristic of the circuit 3 to be flat at a required frequency band. The frequency characteristic of the field signals S1, S2 obtained through the changeover of the switch 2 is coincident so as not to cause any level difference between odd/even number fields of the frame signal formed in this way.

Description

[Detailed Description of the Invention] Field of Commercial Use The present invention relates to a frequency characteristic correction circuit in a conversion method from a field signal to a frame signal. This is to be corrected.

Conventional technology: In the method of recording video signals on recording media such as magnetic tapes and magnetic disks, one track is recorded per field or two fields in order to facilitate special playback of still images, slow motion, etc. The assigned video signal changes in frame period or field period. If one track is allocated to one field,
Synthetic video 1# that says synchronization signal! A method in which only odd field signals are recorded, and during playback, the same field is scanned twice to obtain a composite video signal for one frame, that is, a composite video signal for one field. (hereinafter referred to as Feel Toy M) to synthesize one frame of I! !
A conversion method to an Ii' image signal (hereinafter referred to as a frame signal) is also frequently used.

The main purpose of this is to increase the recording density of the recording medium.

In order to actually see interlaced scanning in such a method of converting a field signal to frame No. 18, special measures must be taken instead of simply returning the field signal to a rate of 2n# and reproducing it. That is, a time difference of /2 horizontal fixed period (hereinafter referred to as l/2H) is required between the video signal of the odd field and the video signal of the even field.

More specifically, when looking at FIG. 1, the horizontal scan edges of the odd fields are shown in solid outline, and those of the even fields are shown in dotted lines. As we will see, for example, if an l frame consists of 525 water half-scans,
The odd field ends at the center of the 263rd scanning line 263H, that is, at 262.5H, and thereafter becomes an even field. Therefore, in order to form a correct animal image as an even field from the beginning of ÷264H, it is necessary to
The contents of the 64H video signal must correspond correctly to the contents of the IH video signal. Since the field image No. 18 supplied from the magnetic disk returns from 2655H to the beginning of OH, 1), in order to correspond correctly in this way, the even field image signal must be It must be delayed by a period substantially equal to half the 1H period relative to that of the odd field.

Therefore, in this woodcutter's conversion method according to the prior art, the field signal delayed by 1/2H by the delay circuit and the field signal through Z+ and -a are alternately selected for each lv by switching a switch. There is.

However, delay circuits generally have frequency characteristics. Incidentally, when the video signal is a standard signal of the NTSC system, its occupied frequency band is 0 to 41 VHz, and it can have flat frequency characteristics throughout this band.
The amplitude in the local frequency domain will decrease. That is, the luminance signal Y in the high frequency region (4Ml (near z)) and the carrier color difference signal CHR (JMA receive its shadow).

Therefore, the through video signal (odd field
I! When comparing the field signal (even field video signal) delayed by 1/2h, both ministries are ^
The levels in the frequency domain will be different, resulting in flickering when reproduced on a screen.

10,000, the gain of the carrier color difference signal amplifier in the monitor is
This A increases as the input level decreases due to the ACC (automatic color controller).
The frequency characteristics of the delay circuit can be corrected by CC, but once the gain is maximized by ACC, it is proportional to the input level after that, so in this region, the frequency characteristics of the delay circuit cannot be stopped even by ACC. Can not.

OBJECTS OF THE INVENTION Based on the above-mentioned prior art, the present invention provides a conversion method from a field signal to a frame signal that corrects the output of a delay circuit to have a 7-rant frequency characteristic in a required frequency band. The purpose is to

Structure of the Invention The invention for achieving the above object consists of a field delay circuit which is delayed by a 51/2 horizontal constant distortion period by passing through a delay circuit;
In a conversion method from a field signal to a frame signal, which alternately selects and converts other field signals into frame signals by switching a switch, a delay circuit is interposed between a delay circuit and a switch. The delay circuit is characterized in that the delay circuit corrects the characteristics of the non-flat portion of the frequency characteristics so that the frequency characteristics are flat in a required frequency band.

Effects of the Invention The present invention is characterized by the fact that the frequency characteristics of the field signal passed through the M/A circuit can be made to match the frequency characteristics of the field signal that is not connected, so that the frame signal formed by both field toy d There is no ζ, which causes the linker to appear on the screen you get by playing.

Practical example Hereinafter, implementation v0 of the present invention will be explained in detail based on the drawings.

As shown in FIG. 2, a field signal S1, for example standard No. 16 of the N'rSC system, is supplied to an input terminal 1. Switch 2i1: has two contacts 2a and 2b, and by selecting any one of these contacts 2at2b, the through field signal S□ and this are delayed by 1/2H period by delay 1 path 3. &fv (
fv is the vertical scanning frequency] and is alternately selected every 1V period using a control signal S4. Thus, from the output terminal 5, frame No. 16 S3 is sent out, in which the odd fields are the field signals Sl and the even fields are the field signals S2. At this time, a frequency characteristic correction circuit 6 is connected between the delay circuit 3 and the point 2b of the switch 2.

This frequency characteristic correction circuit 6 stops the delay circuit 30 so that the frequency characteristic falls within the required frequency range (0 to 41 VIHz in the example) and becomes flat.

Therefore switch 20'! #The frequency characteristics of the field signals S, S2 obtained by IJ conversion are the same, and the level difference 2 between odd and even fields in the frame signal formed by these will not occur. This refers to n-fake and CHRO+JA.
Standards for the SC method (I have described the one that generates i!, but the scope is not limited to this, for example, brightness and C) 1)
It is also useful to use one path of 14 anti-signals when converting each LUMAk separately to a field/frame.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing interlaced scanning of an image using the NTSCy5 method, and FIG. 2 is a pronk diagram showing a 1M example of the present invention. In the drawing, 2a is a switch, 3 is a delay circuit, and 6 is a frequency characteristic correction circuit. Special fraud applicant Fuji Photo Film Co., Ltd. Representative Patent attorney Hikaru Ishibe (and 1 other person)

Claims (1)

[Claims] A field signal that is delayed by 1/2 horizontal scanning period by passing through a delay circuit and an h field signal that is not delayed are alternately selected every 1 vertical scanning period by switching a switch, and converted into 6 frames per frame. In the conversion method from a signal to a 7-ray 15-signal signal, the delay circuit is interposed between the delay circuit and the switch, and the 7-rat round part of the frequency characteristic is inserted so that the delay path has a flat frequency characteristic in the required frequency band. A frequency characteristic correction circuit in a field signal to frame signal conversion method, characterized in that the frequency characteristic correction circuit corrects the characteristics of the field signal to frame signal.