JPS59112780A - Character display correction system of vtr - Google Patents

Abstract

PURPOSE:To prevent an inserted character from oscillation vertically by generating a new vertical synchronizing signal which syncyronizes with a composite signal and controlling a vertical display position by the vertical synchronizing signal. CONSTITUTION:The Q output of a retriggerable monostable multivibrator 14 is varied to a level H by the vertical synchronizing signal VSYNC. Then the retriggerable monostable multivibrator 14 is triggered by the output of the counter 13A of a horizontal display position control circuit 13 which inputs the composite signal CSYNC. Consequently, the retriggerable monostable multivibrator 14 operates by the output of the counter 13A corresponding to equalized pulses of the composite signal CSYNC even after the vertical synchronizing signal VSYNC is ceased, and its Q output returns to a level H after an equalized pulse period ends. The counter of a vertical display position circuit is limited by a new vertical synchronizing signal NewVSYNC which synchronizes with the composite signal CSYNC.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a character display correction method in a character generation/insertion circuit built into a VTR (video tape recorder), and is particularly applicable to areas where the electric field strength of TV radio waves is weak or where there is a lot of noise. The present invention also relates to a character display correction method that prevents vibrations of characters inserted into a received image in the vertical direction and provides a high-quality character insertion screen.

Conventional technology In consumer VTRs, a method is known in which a circuit for generating and inserting character information is added to the video camera so that the date of recording and other character information can be recorded simultaneously with the video signal. .

However, with this method, text information cannot be inserted into the received image of TV radio waves.

In order to insert text information into the received image of TV radio waves, V
It is necessary to provide a character generation and insertion circuit within the TR body. However, such a VTR is not yet known.

Prerequisite technology When recording received images of TV radio waves on a VTR and inserting the recording date, date and time, and other character information,
Simply adding a character generation/insertion circuit to the VTR body will cause the display position of the inserted characters to vibrate vertically or horizontally due to the field strength of the received radio waves, noise, etc.
This has the disadvantage that image quality deteriorates.

FIG. 7 is a schematic block diagram showing the overall configuration of the VTR to show the position of the character generation/insertion circuit where the display correction is performed in the VTR character display correction method of the present invention. In the drawing, / is a television antenna, U is a tuner, 3 is a video signal processing section, 3/ is its luminance signal recording system, 3 U is a color signal recording system, 33 is a tape head system,
3G is the luminance signal reproduction system, 3S is the color signal reproduction system, Hiroshi is the audio signal processing section, II/ is the audio signal recording system,
lI is the tape head system, l13 is the audio signal reproduction system,
5 is an RF converter, O is a television receiver, and 7 is a character generation/insertion circuit.

The VTR is connected between the television antenna and the television receiver B. In so-called home video for consumer use, in order to save recording bandwidth, the tuner l converts the signal into a low frequency carrier color signal, superimposes it with an FM modulated luminance signal, and records it on a video track of a magnetic tape.

Furthermore, audio data is similarly recorded on the audio track.

During playback, the video and audio signals are read by their respective heads, sent to the RF converter 5, and displayed on the TV screen by the TV receiver B.

By the way, in the case of the NTSC system, the TV screen is composed of horizontal scanning lines on the left side, and 6θ images are displayed in 7 seconds.

The video signal includes a horizontal synchronization signal for scanning the screen in the horizontal direction and a vertical synchronization signal for scanning in the vertical direction.

Figures 2 (1) and (2) are examples of video signal waveforms.
1) shows the state of the horizontal synchronizing signal, and FIG. 2 shows the state of the vertical synchronizing signal. In the drawing, H8YNC is a horizontal synchronizing signal and 5YNC is a vertical synchronizing signal.

When inserting characters onto a TV screen, one possible method is to determine the position of one character by counting pulses based on these synchronization signals.

FIG. 3 is a screen diagram illustrating a method for specifying seven points on the TV screen. In the drawing, P indicates the position of the point you want to indicate, and T1 is the distance from the top of the screen to the position P, and T
2 indicates the distance of position P from the left edge of the screen.

When specifying the position P in FIG. 3, the vertical synchronizing signal "8YNC" is used as the upper end reference, and the horizontal synchronizing signal H87NC is used as the left end reference.

FIG. 7 is a block diagram showing an example of a circuit for detecting distances T1 and T2 for indicating the position P in FIG. 3. In the drawings, gh is a synchronization signal separation circuit, gB is a vertical synchronization signal detection circuit, gc is a horizontal synchronization signal detection circuit, gD is a first counter, and zaE is a third counter.

The distance T1 from the upper end of the position P of the seven points in FIG. 3 is detected by the first counter gD.

That is, this first counter gD receives the vertical synchronization signal V
Reset by 8YNC, horizontal synchronization signal H correction NC
count.

Further, the distance T from the left end of the first position P is detected by the second counter gE. To this end, this third counter gE is reset by the horizontal synchronizing signal H8YNC, and counts, for example, the input clock of 3.3-gMH2 of the carrier color signal or another frequency.

The position of the character to be inserted can be set using the circuit shown in the figure.

FIG. 5 is a basic block diagram showing the mounting position of the character generation/insertion circuit when inserting characters into the TV screen and an example of character display on the TV screen.

The reference numerals in the drawing are the same as those in FIG. 1, and 7/ indicates a synchronization separation circuit, 7 indicates a character creation circuit, and 73 indicates a character insertion circuit.

The synchronization separation circuit 7 has the same configuration as the separation circuit gA in the previous figure, and separates the horizontal synchronization signal and vertical synchronization signal from the input video signal, and determines the position on the screen of the television receiver B. Detect.

The character creation circuit 7U generates character information such as date, month, date, etc.
It is output to the character insertion circuit 3 at the timing from the synchronization separation circuit 7/.

As the character insertion circuit 73, for example, an analog switch is used, and the five character information and the video signal are combined and sent to the television receiver 6, so that the characters are displayed at a predetermined position on the screen.

In this case, the horizontal synchronization signal and vertical synchronization signal taken out by the synchronization separation island 7 circuit 7/ may cause the inserted characters to vibrate vertically and horizontally in areas where there is a lot of noise when the electric field strength of TV radio waves is weak. , the screen becomes difficult to read.

FIG. 6 is a diagram showing a state in which the character position inserted on the TV screen vibrates in the vertical direction.

The reason why the inserted characters vibrate in the vertical direction is that noise or jitter appears in the synchronized and separated synchronization signal used to determine the display position of the characters.

That is, as already explained in connection with FIG. 3 and TTTM, the display position of the characters to be inserted on the TV screen is determined by the vertical display position control circuit and the horizontal display position control circuit provided in the character generation and insertion circuit. It is determined.

Specifically, the vertical display position control circuit receives the vertical synchronization signal V
IIIYNC as a reset signal, composite (Co
mposite) signal C5YNC as a clock signal.

FIG. 7 is a time chart showing the relationship between the composite signal and the vertical synchronization signal input to the vertical display position control circuit.

In addition to the horizontal synchronization signal, the composite signal c8YNc also includes a vertical synchronization pulse and equalization pulses arranged before and after the vertical synchronization pulse.

Therefore, if the composite signal C3YNC or vertical synchronization signal ■8YNC fluctuates due to TV radio noise, etc.,
The pulse of arrow Q may or may not be counted, causing the internal counter to miscount. Therefore,
The display position of the characters is distorted and the characters vibrate in the vertical direction as shown in Figure 6, making the screen difficult to read.

Purpose Therefore, in the VTR character display correction method of the present invention, such inconveniences in the 5 character generation and insertion circuit are solved, and the T.
Even in areas where the electric field strength of V's received radio waves is weak or where there is a lot of noise, the vertical vibration of the inserted characters can be prevented.
The purpose is to make it possible to obtain high-quality character insertion on both sides.

Structure For this purpose, the character display correction method of the present invention focuses on the fact that the horizontal display position control circuit is not used during the vertical retrace period, and uses this circuit to synchronize with the composite signal C5YNC by its output. Means for creating a new vertical synchronization signal created by the creation means is provided, and an internal counter of the vertical position control circuit is reset with the new vertical synchronization signal created by this creation means.

For purposes of explanation, a character generation/insertion circuit built into a VTR will be briefly described.

FIG. g is a block diagram showing the position of the character generation/insertion circuit 7 in the brightness signal system of the VTR. In the drawing, waA-9H indicates the recording side, qA is LPF%, and 9B is AG
C, qC are bright emphasis, 9D is white clip/dark clip, qE is clamp %, 9F is FM modulator, 9G is HPF, 9H is recording amplifier, 10 is video head, IOA is its rotating transformer, // is Magnetic tape.

7.2A~/J indicates the playback side, 7.2 and /2B the playback preamplifier, /JC the switcher 1/D) (
PF, /, 2E is DOC, 72F is limiter, /Jl-
1! FM demodulator, /2H is de-emphasis, /II is LPF, /, 2J is output amplifier.

The color video signal given from the video signal input is combined with the character information given from the character generation/insertion circuit 7,
I, PF? Input to A.

The LPF 9A removes the carrier color signal and extracts only the luminance signal. At the same time, the mixing of the 11.3 MHz audio carrier wave and high-frequency component noise is also prevented.

In the next AGC9B, in order to match the timing of the luminance signal and the carrier color signal, the timing is delayed by about /μsec.
Adjustment is made so that the optimum input level of 2 to the FM modulator 9F is obtained.

The level-adjusted signal is subjected to high-frequency enhancement using a high-frequency emphasis qC, and is applied to a white clip and a dark clip qD. Here, overshoot and undershoot are removed, and the ends of the synchronization signals are aligned in a straight line by the clamp 9E.

Then, it is FM modulated by FM modulator 9F, and further HPF
? At step G, the portion of the lower sideband that overlaps with the band of the low frequency conversion carrier color signal is removed and sent to the recording amplifier 9H.

The video signal amplified to the optimum level by the recording amplifier 9H is
The signal is supplied to the video head 10 and recorded on the magnetic tape.

In this way, a video signal in which characters are inserted into a video signal of %TV radio waves is recorded.

During reproduction, the video signals alternately reproduced by the two video heads 10 are sent to the reproduction preamplifier i via a rotating transformer.
amplified by sh and icoB, respectively.

It is selected by switcher/2C and becomes a continuous video signal.

This video signal is converted into an FM luminance signal by cutting off the low frequency conversion color signal component below MHz using HPF/2D.
The noticeable dropouts are corrected in the next DOC/2E.

The corrected luminance signal is input to the FM demodulator/JG via a limiter/2F that determines the dropout detection level.

The demodulated luminance signal is returned to the original signal before high-frequency boost by de-emphasis 7.2H, with characteristics opposite to the blue emphasis during recording, and is roughly L P F /
The remaining FM component is removed in JI.

And output amplifier/:1. The signal is amplified to a predetermined level by J and outputted.

The character display correction method of the present invention prevents vertical vibration of inserted characters in the character generation/insertion circuit 7 built into the VTR shown in FIG. 4g.

FIG. 9 is a block diagram showing an example of a new vertical synchronization signal generating means used to implement the character display correction method of the present invention. In the drawing, /3 is the horizontal display position control circuit, /3 is its counter, /ritto/left is the Ridrigger mono multivibrator %, /6 is the inverter, /7 is the OR gate circuit, and NewVs
lNc indicates a new vertical synchronization signal synchronized with the composite signal.

The circuit of FIG. 9 takes advantage of the fact that the horizontal display position control circuit /3 is not used during the vertical retrace period, and uses its output to create a new vertical synchronization signal 1'Jew synchronized with the composite signal CBYNC. This is to create V8YNC.

FIG. 1O is a time chart for explaining the operation of the circuit of FIG. 9. The symbols attached to each signal waveform correspond to the symbol positions in FIG.

As already explained in connection with FIG. 7, the composite signal CBYNC also includes vertical synchronization pulses and equalization pulses.

The vertical synchronization signal vsYNc falls at the equalization pulse that follows the vertical synchronization pulse of the composite signal csyNc. This falling position is.

It fluctuates due to the influence of noise, etc.

Therefore, by using the circuit shown in Fig. 3, the vertical synchronizing signal V8YN
Instead of C, a new vertical synchronizing signal NevrVSYNC synchronized with the composite signal CflYNc is created, and the vertical display position of the inserted character is controlled by this new vertical synchronizing signal Newv8YNc.

Namely, Ridriger Mono Multivibrator/4'
is used, and its output Q is changed to H level by the vertical synchronization signal vsyNc. And composite signal cs
Horizontal display position control circuit/3 counter to which yNc is input/? By the output of A, Ridriger Mono Multi/l
Ridriger I.

In this case, the setting time of the lidliquor monomulti/lI is set to an intermediate value between the equalization pulse and the horizontal synchronization pulse, for example, 1 sec.

In this way, even if the vertical synchronization signal V8YNC ends, the IJ) IJ Gar Mono multiplier will continue to use the counter/
,? It is activated by the output of A, and its output Q returns to the L level after the equalization pulse period ends.

Therefore, Ridriger Monomultipuffer comes out.

By resetting a counter of a vertical display position control circuit (not shown) using this new vertical synchronization signal NeVr VSYNC, it is possible to completely prevent miscounts from occurring.

In addition, Ridriger Monomulti/! r is the counter/3A of the horizontal display position control circuit/3 that receives the vertical synchronizing signal V8Y.
The vertical synchronization pulse of the composite signal CBrNC input during the NC period is controlled not to be counted.

It should be noted that various modifications other than the circuit shown in FIG. 9 are possible as means for creating the new vertical synchronization signal New V-revised NC, and the circuit is not limited to the circuit shown in FIG.

As explained in detail above, the character display correction method of the present invention takes advantage of the fact that the horizontal display position control circuit is not used during the vertical retrace period, and also uses the characteristics of the composite signal. A new vertical synchronization signal New v8YN synchronized with the composite signal
c is generated, and the vertical display position is controlled by this new vertical synchronizing signal. .

Effects Therefore, according to the VTR character display correction method of the present invention, in the character generation and insertion circuit built into the VTR,
Even in areas where the reception field of TV radio waves is weak or where there is a lot of noise, vertical vibration of inserted characters can be prevented and a high-quality character insertion screen can be obtained.

Furthermore, since a part of the horizontal display position control circuit can be used in common for the circuit used for this purpose, there are many excellent effects such as minimizing the increase in cost. can get.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing the overall configuration of a VTR to indicate the position of the character generation/insertion circuit in which display correction is performed by the VTR character display correction method of the present invention.
) and (2) are examples of video signal waveforms, Fig. 3 is a screen diagram explaining how to specify seven points on the TV screen, and Fig. 7 is an example of the waveform of a video signal.
Distances T8 and T! for indicating the positions of the seven points in the figure! Figure 3 is a basic block diagram showing the mounting position of the character generation/insertion circuit when inserting characters into the TV screen, and an example of character display on the TV screen. A diagram showing how a character position inserted on the screen vibrates in the vertical direction, Figure 7 is a time chart showing the relationship between the composite signal input to the vertical display position control circuit and the vertical synchronization signal, and Figure g is a VTR. FIG. 9 is a block diagram showing the position of the character generation/insertion circuit in the luminance signal system of the present invention, and FIG. Figure, 1st θ
This figure is a time chart for explaining the operation of the circuit of FIG. 9. In the drawing, 3 is a tuner, 3 is a video signal processing unit, 3 is an audio signal processing unit, 7 is an RF converter, 7 is a character generation/insertion circuit, /3 is a horizontal display position control circuit, and /3 is a horizontal display position control circuit. Counter, /G and /S are Lidrinker.
A mono multivibrator is shown. Sweet 2 ~ Figure 3 (2) 8A, 83 years old 4 Figure'------~-Jo 5 Figure 〉 ;A: 9 Figure Sai 10 Figure procedure sleeve formal letter (self-prompted) Date of A, 3, Showa Sagar Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office■ Indication of the case 1981 Special H'1^1 Page No. 3 'Ig: No. 3 2 Name of the invention VTR character display correction method 8 Relationship to the case of person who corrects sleeves Patent application Ricoh Co., Ltd., 3-6 Nakamagome, Ota-ku, Tokyo (A?Il) - Contents of the amendment in column 6 of detailed description of the invention in column 3 of the description of the minor agent

Claims (1)

[Claims] In the character generation/insertion circuit built into the VTR, means is provided for creating a new vertical synchronization signal synchronized with the composite signal using the output generated from the horizontal display position control circuit during the vertical retrace period, and the creation means is used to create a new vertical synchronization signal synchronized with the composite signal. A character display correction method characterized by controlling the vertical display position using a new vertical synchronization signal.