JPH04115683A - Video tape recorder - Google Patents

Abstract

PURPOSE:To eliminate a V fluctuation at the time of viewing screen and the turbulence of a screen at the time of special reproduction by changing synchronous timing automatically at the time of normal teletext screen viewing and at the time of recording of a teletext picture. CONSTITUTION:When a teletext control part 6 receivers VTR mode changing information from a VTR control part 13, the condition of a current display screen is checked, and if it is teletext screen display, it is checked whether a VTR mode after changing is recording or not, and when it is the recording, an instruction is outputted to a teletext decoder 7 so as to make the display synchronizing timing into the 312/313 non-interlacing and the synchronous timing of an output signal (c) is set to 312/313 non-interlacing. On the other hand, when the VTR mode is not the recording and the synchronous timing of the current display is the 312/313 non-interlacing, the control part 6 outputs the instruction to the teletext decoder 7 so as to make the display synchronous timing into the 312/313 non--interlacing and set the synchronous timing of the output signal (c) to the 312/313 non-interlacing. Thus, the turbulence of a picture is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a video tape recorder (VTR) capable of receiving teletext broadcasts.

(b) Conventional technology Currently, the teletext decoder IC used in VTRs equipped with teletext receivers, which are commonly used mainly in Europe, has a synchronization timing ( The method of scanning can be changed in several ways. Types of this synchronization timing include, for example, 312/313 interlace, 312/313 non-interlace, and 312/312 non-interlace. When a certain type of synchronization timing is selected from among these three synchronization timings, depending on the type of PAL television (TV) receiver that receives the selected synchronization timing, V backlash (vertical shaking of the image) may occur. may occur. The synchronization timing at which this V play is likely to occur is in the case of 312/313 interlacing among the three types described above.

Therefore, in order to display a teletext screen on a TV receiver, scanning methods other than the above-mentioned 312/313 interlace,
In other words, 312/313 non-interlaced data is 3
It turns out that 12/312 non-interlaced synchronization timing should be selected.

However, when a certain type of digital TV receiver and a VTR equipped with the teletext receiving device are connected via an AV line, if the synchronization timing is set to 312/313 non-interlace, the TV receiver will adjust the synchronization timing. There is a problem that V backlash occurs due to misjudgment, and this problem is due to the following reasons.

In other words, general digital TV receivers synchronize with the CCIR standard 313 interlace (scanning at 312.5 lines in the first field and 312.5 lines in the second field) when viewing normal TV broadcasts. However, if there is a change in the synchronization timing due to a channel change, etc., synchronization will be set at that timing, and the synchronization timing will also be checked when the display changes from the TV screen to the teletext screen. It has become. However, in the above-mentioned kind of digital TV receiver, synchronization timing is determined based on the number of lines per frame, and therefore, in such a TV receiver, 313
Interlaced (number of scanning lines that make up one screen: 312.
5x2=625) and 312/313 non-interlaced (number of scanning lines that make up one screen: 312+313=62)
5) cannot be distinguished, and even if the synchronization timing changes from 313 interlace to 312/313 non-interlace, it remains 313 interlace.

For this reason, conventionally, in order to solve the above-mentioned gap, VTR
The teletext decoder IC installed in the system set the synchronization timing when displaying the teletext screen to 312/312 non-interlace.

(c) Problems to be Solved by the Invention However, with the 312/312 non-interlace synchronization timing, when recording a teletext screen,
When performing special playback such as slow, still, or search on the recorded teletext screen, the servo is not applied and the screen becomes distorted, which results in a problem.

Therefore, the present invention seeks to solve such problems.

(d) Means for Solving the Problems The present invention is capable of capturing teletext data superimposed on the vertical blanking period of a television video signal, and a teletext screen formed by the captured teletext data. In order to solve the above-mentioned problem in a video tape recorder that is capable of recording, a screen scanning method for forming a teletext screen has been developed for both when recording a teletext screen and when viewing a teletext screen other than recording. Made it switch automatically.

(E) Effect According to the above means, when viewing a normal teletext screen,
By automatically changing the synchronization timing when recording a teletext screen, it is possible to eliminate screen disturbances even during special playback of a normal teletext screen.

(F) Example Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a schematic block diagram of a VTR embodying the present invention, in which a broadcast signal captured by an antenna 1 is selected for reception by a tuner 2, and a video intermediate frequency and detection circuit (I
The signal is input to the video signal processing circuit 4 via the F-DET) 3, where the signal is processed and supplied to the display/recording signal switching circuit 5.

This display/recording signal switching circuit 5 is configured to switch between a video signal from the video signal processing circuit 4 or a character signal from the teletext decoder 7 in response to a switching signal a from a teletext control section 6 constituted by a microcomputer. selects and outputs a composite signal C of a character signal and a video signal. The output of the display/recording signal switching circuit 5 is supplied to an output terminal (not shown) for display, and is also supplied to the recording circuit 15 for recording.

On the other hand, the teletext signal multiplexed during the vertical retrace period among the video signals obtained from the IF-DET 3 is extracted by the teletext signal extracting circuit 8 and supplied to the teletext decoder 7. This teletext decoder 7 extracts only the data of the page number instructed by the teletext control section 6 and supplies it to the screen memory 9.

The screen memory 9 writes the screen data of the specific page number selected by the teletext decoder 7 in accordance with the control signal from the teletext control section 6.

The data written in the screen memory 9 is read out in accordance with a control signal from the teletext control section 6, and then converted into a character signal by a teletext decoder 7.

The teletext control section 6 not only controls the display of the television screen and the teletext screen by sending commands to the teletext decoder 7 and the display/recording signal switching circuit 5 as described above, but also writes data directly to the screen memory 9. You can also display arbitrary characters.

Input signals input by operating the remote control transmitter 10 and the keyboard 11 provided on the VTR body are converted into a common code signal by the input control section 12 and then input to the VTR control section 13. This V T
RII! Control section 13 controls the channel selection circuit 14 to select a channel according to the content of the code signal from the power control section 12, and controls various operations of the VTR, that is, controls the recording circuit 15 to execute recording. , performs operations such as playback, fast forwarding, rewinding, and stopping, and makes program recording reservations, and also supplies codes related to teletext control to the teletext control unit 6.

Next, with reference to FIGS. 1 and 2, the operation of the teletext control unit 6 in switching the synchronization timing between normal teletext screen viewing and teletext screen recording will be described in detail.

The teletext control section 6 receives the VTR from the VTR control section 13.
It is always waiting for the information about the change in the mode of the VTR, that is, from stop to playback, from stop to recording, etc. (step 1),
When the TR mode change information is received, the process proceeds to step 2.

In step 2, it is checked whether the current state of the display screen is a teletext screen display (that is, whether the signal switching circuit 5 has selected signal C), and if it is a teletext screen display, the process proceeds to step 3. In step 3, VT after change
Check whether the R mode is recording, and if it is recording, proceed to step 4. In step 4, the control section 6 instructs the teletext decoder 7 to set the synchronization timing of the display to 312/313 non-interlace, and the teletext decoder 7 synchronizes the output signal C according to the instruction of the control section 6. Set the timing to 312/313 non-interlaced. Therefore, since the VTR records the teletext screen in 312/313 non-interlace, disturbances such as skinny distortion do not occur during playback.

On the other hand, if the changed VTR mode is not recording in step 3, the process proceeds to step 5, and if the current display synchronization timing is 312/313 non-interlace in step 5, the process proceeds to step 6. In step 6, the control section 6 instructs the teletext decoder 7 to set the display synchronization timing to 312/312 non-interlace, and the teletext decoder 7 synchronizes the output signal C according to the instruction of the control section 6. Set the timing to 312/312 non-interlaced. Therefore, when viewing on a TV receiver using a VTR teletext device, the synchronization timing of the teletext screen from the VTR is 312/312.
Since it is non-interlaced, there will be no V jitter in any TV receiver.

Through the above-described series of operations, the synchronization timing for teletext screen display can be automatically switched to 312/312 non-interlace during normal teletext screen viewing and 312/313 non-interlace during teletext screen recording.

(G) Effects of the Invention As described above, according to the present invention, by automatically changing the synchronization timing between normal teletext screen viewing and teletext screen recording, V This has the effect of not only making it possible to view the screen without any wobble, but also eliminating screen disturbances even during special playback of recorded teletext screens.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a main part of a video tape recorder embodying the present invention, and FIG. 2 is a flowchart for explaining its operation. (5)...Display/recording signal switching circuit, (6)...
・Teletext control circuit, (7)...Teletext decoder, (8)...Teletext signal extraction circuit,
(10)...Remote control transmitter.

Claims (1)

[Claims] (1) A video tape recorder capable of capturing teletext data superimposed on the vertical blanking period of a television video signal and capable of recording a teletext screen formed by the captured teletext data. A video tape recorder characterized in that a screen scanning method for forming a teletext screen is automatically switched between when recording a text screen and when viewing a teletext screen other than recording.