JPH04332277A - Television receiver - Google Patents

Abstract

PURPOSE:To prevent a synchronizing turbulence due to the noise of an on-screen signal by inputting an outside video signal without any mixed noise signal to a synchronizing separator deflection circuit at the time of displaying the on-screen signal on an entire screen. CONSTITUTION:An on screen signal generating circuit 5 transmits an input switching signal to a signal switching circuit 4 by a non-signal judging signal from a tuner VIF circuit 1. Then, at the time of displaying a character or a graphic signal(on-screen signal) generated in the inside of a television receiver on an entire screen, and also when a tuner VFI signal is the non-signal, the signal switching circuit 4 is switched from an input terminal a from the tuner VIF circuit 1 to an outside video signal input terminal b. Thus, the noise signal from the tuner VIF circuit 1 can be prevented from being mixed with a synchronizing separator deflection circuit 3. Therefore, the pulse of a horizontal and vertical synchronizing signal supplied to the on screen signal generating circuit 5 can be turned into the synchronizing signal pulse in a constant period.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver that displays character or graphic signals generated by an internal circuit on a screen.

0002

2. Description of the Related Art In recent years, integrated circuits that generate character or graphic signals internally in television receivers have become widely available because they are available at low cost.

A conventional television receiver that displays text or graphic signals (hereinafter referred to as on-screen signals) on a screen will be described below. As shown in FIG. 3, generally in a television receiver, a tuner VIF circuit 1 receives external television broadcast waves and applies them to a signal switching circuit 4. The signal switching circuit 4 is connected to an external video signal from a video tape recorder or the like and the tuner VIF circuit 1 described above.
A video signal from a television broadcast wave received by the user is added thereto, and a signal is selected by an input switching signal from the control signal generating circuit 6 by operation on the user side. The output signal from the signal switching circuit 4 is applied to the video signal amplification circuit 2 and the synchronous separation/deflection circuit 3. The output from the video signal amplification circuit 2 is applied to the picture tube 7 and an image is displayed on the picture tube surface. The output signal from the synchronous separation deflection circuit 3 supplies a deflection current to a deflection coil 8 attached to the picture tube 7. Further, the synchronization separation/deflection circuit 3 supplies vertical and horizontal scanning synchronization signal pulses to the on-screen signal generation circuit 5, and the on-screen signal generated in the on-screen signal generation circuit 5 is used to display an image on the screen of the picture tube 7. It is synchronized with the signal.

0004

[Problems to be Solved by the Invention] However, in the above conventional configuration, when the tuner VIF input signal is no signal,
Since a noise signal is applied to the synchronization separation/deflection circuit 3, even if an on-screen signal such as a channel display is generated within the television receiver, the horizontal and vertical scanning synchronization on the picture tube screen will not be constant and will be disturbed. be done. As a result, the on-screen signal also has distorted characters as shown in FIGS. 4(a) and 4(b). In this case, when a character signal is displayed in a small size on a part of the screen as shown in FIG. 4(b), a noise signal is displayed in the background, so that it does not give a very unnatural feeling to the user. However, when a large on-screen signal is displayed over the entire screen instead of the video signal as shown in FIG. 4(a), synchronization is disrupted and the image becomes distorted and difficult to view.

[0005] The present invention solves the above-mentioned conventional problems, and provides a television set that is arranged so that on-screen signals for displaying channels will not be out of synchronization when receiving a channel for which no television broadcast radio waves are available. The purpose is to provide a receiver.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the television receiver of the present invention, when displaying an on-screen signal on the entire screen, transmits the video signal input to the synchronization separation circuit to the antenna and tuner. It has a configuration in which the signal received by the external video signal is switched to the external video signal, and the synchronization of the on-screen signal is switched to the external video signal side.

[0007]

According to the present invention, with the above-described structure, the synchronization of the on-screen signal is not disturbed by inputting an external video signal that does not contain any noise signals into the synchronization separation circuit.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, FIG.
The difference is that when the no-signal determination signal is transmitted from the tuner VIF circuit 1 that receives television broadcast waves from the outside to the on-screen signal generation circuit 5, the input switching signal from the on-screen signal generation circuit 5 becomes a signal. The configuration is such that the information is transmitted to the switching circuit 4.

Regarding the television receiver of the present invention configured as described above, in particular, the case shown in FIG. 2 in which an on-screen signal such as a channel number is projected on the screen of the picture tube 7 is displayed on the entire screen. And, tuner VIF
When the received signal from the circuit 1 is in a no-signal state, the input switching signal output from the on-screen signal generation circuit 5 is transmitted to the signal switching circuit 4, and the external video signal is output from the input terminal (a) from the tuner VIF circuit 1. Switch to input terminal (b). By the above operation, the synchronous separation deflection circuit 3
In this case, the pulses of the horizontal and vertical synchronizing signals supplied to the on-screen signal generating circuit 5 also become synchronizing signal pulses of a constant period without being mixed with noise signals from the tuner VIF circuit 1.

The control signal generating circuit 6 shown in FIG. 1 is capable of receiving a remote control input signal from the outside and switching the signal switching circuit 4.

0012

As described above, the on-screen signal generation circuit of the television receiver of the present invention allows the on-screen signal to be displayed due to noise even when there is no external television broadcast signal applied to the tuner. The signal is not disturbed, and it is possible to display a stable and easy-to-see image as shown in Fig. 2.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a television receiver according to an embodiment of the present invention.

FIG. 2 is a plan view showing an on-screen display screen of a television receiver in an embodiment of the present invention.

[Figure 3] Block diagram of a conventional television receiver

FIG. 4 (a) A plan view showing an on-screen display screen of a conventional television receiver. (b) A plan view showing an on-screen display screen of a conventional television receiver.

[Explanation of symbols]

1 Tuner VIF circuit 3 Synchronous separation/deflection circuit 4 Signal switching circuit 5 On-screen signal generation circuit 6 Control signal generation circuit 7 Picture tube

Claims (1)

[Claims] Claim 1: When a character or graphic signal generated inside a television receiver is switched to an external television broadcast signal and displayed on a screen on a picture tube surface, an input signal to a synchronous separation/deflection circuit is used as a signal. A television receiver having means for switching to an external video signal side in a switching circuit.