JPH0516787Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field The present invention is applicable to the so-called on-screen display in television receivers in which characters indicating the channel number and playback mode such as "Video 1" are displayed on the receiving screen. Regarding the type of television receiver.

(b) Prior Art In a television receiver with an on-screen display as described in the introduction, for example, as described in Japanese Patent Publication No. 60-38071, when the power is turned on, when changing channels, or when switching between video and television, When the same channel (including the so-called video channel during VTR playback; the same applies hereinafter) is being received, the above on-screen display will be displayed automatically for a certain period of time until the recall is canceled only when the recall key is operated. We are continuing to do so.

By the way, continuous on-screen display during reception by operating the recall key is generally not done because the characters on the screen become an eyesore. This is because even if you do not do this, if a TV image or a VTR reproduced image is actually being displayed, the currently selected channel can be easily determined from the contents.

However, when a television broadcast or a VTR reproduced image is interrupted, that is, when no video signal is input, it is inconvenient that the current channel cannot be determined unless the channel number is called up using the recall key. This is especially true in the case of a receiver that is equipped with multiple video input terminals, that is, multiple video channels, and is capable of selectively displaying a VTR playback signal introduced into each video channel.

(c) Problems that the invention aims to solve This invention was created in view of the above points,
It is an object of the present invention to propose a television receiver capable of knowing the current channel (or playback mode) without operating a recall key on an on-screen display when no video signal is input.

(d) Means for solving the problem The television receiver of the present invention is provided with a detection circuit that detects the presence or absence of a video signal input, and when this detection circuit detects that no video signal is input, a character is displayed. The signal generation circuit was forced to operate.

(E) Effect According to the above configuration, if no image is displayed on the screen when on-screen display is not being performed, the selected source such as the channel number will be automatically displayed. Become.

(F) Embodiment The drawing shows a schematic configuration of an embodiment of a television receiver according to the present invention. In this embodiment, 1 is a tuning circuit including a tuner, 2 is an IF (intermediate frequency) amplification circuit, 3 is a video detection circuit, 4 is a video input terminal for one system, 5 is a TV/video switching circuit, 6 7 is a video amplification circuit, 7 is a sync separation circuit, and 8 is a horizontal and vertical deflection circuit, and these circuits are exactly the same as those in a normal television receiver.

Further, S1 is a TV/video changeover switch, 9 is a TV/video changeover signal generation circuit, and 10 is an output signal thereof or a display pulse which obtains a channel changeover signal from the channel selection circuit 1 and creates a pulse having an on-screen display time width. Generating circuit, S2 is a recall switch with on-screen display, 11 is display on,
The OFF signal generation circuit 12 is an OR gate circuit, and these circuits 9 to 12 constitute a control circuit 14 for the character signal generation circuit 13.

On the other hand, when the switching signal indicating video mode is applied from the switching signal generating circuit 9, the character signal generating circuit 13 converts the character signal "Video" into a predetermined signal determined based on the horizontal and vertical synchronizing signals H and V. When a signal indicating the channel selected by the channel selection circuit 1 is applied, a character signal such as "10" representing the channel number is generated at the timing of The operation is controlled by the output signal of the control circuit 14 , that is, the output of the OR gate circuit 12.

Now, in this embodiment, in a receiver equipped with such an on-screen display function, the synchronous separation circuit 7
A detection circuit 15 is provided to detect the presence or absence of a synchronization signal derived from the control circuit 14.
It is characterized in that it is supplied as the third input of the OR gate circuit 12 in the circuit. That is, the detection circuit 15 is provided to detect the non-input state of the video signal input through the switching circuit 5, and may detect the composite synchronization signal by direct AM detection. Further, it may be configured to detect the presence or absence of an AND output of the horizontal synchronizing signal and the horizontal flyback pulse.

Since the present embodiment is constructed in this way, the output of the detection circuit 15 is at the "L" level when a video signal is input in a television reception state or a VTR playback state. Therefore, in this case, the "H" level pulse derived from the display pulse generation circuit 10 when the channel is switched or the TV/video is switched, or the display is turned on when the recall switch S2 is turned on. “H” derived from the off signal generation circuit 11
Since the level on signal is applied to the character signal generation circuit 13 through the OR gate circuit 12, on-screen display is performed only during each operation.

On the other hand, when the video signal is interrupted during TV reception or VTR playback, the detection circuit 15
The output becomes "H" level, which is applied to the character signal generating circuit 13 through the OR gate circuit 12. Therefore, in this case, the on-screen display of the current channel (including the video channel) is forcibly performed, completely unrelated to the aforementioned recall switch operation, etc.

Although this embodiment has only one video channel, it can be implemented in exactly the same way even when a plurality of video channels are provided, and as described above, the effect is especially great in that case.

(g) Effects of the invention According to the television receiver of the invention, when no video signal is input, this state can be detected and the currently selected channel (or playback mode) can be automatically displayed on-screen. Therefore, there is no need to operate a recall key to confirm the channel mode, and the operability of the receiver is improved. Moreover, since the receiver operates in exactly the same way as a conventional receiver while displaying television images, on-screen characters and the like do not become an eyesore.

[Brief explanation of the drawing]

The drawing is a block diagram of essential parts of an embodiment of a television receiver according to the present invention. 13...Character signal generation circuit, 14 ...Control circuit, 15...Detection circuit.

Claims (1)

[Scope of Claim for Utility Model Registration] A character signal generation circuit for creating display characters such as channel numbers, switching means for selecting an input television signal and an external input signal, and a synchronization signal for each input signal. A detection circuit detects the presence or absence of the display, and generates a display pulse for displaying the display characters for a predetermined period of time when a channel is selected or an external input signal is selected, and when a display-on operation is performed. always generates a display pulse to display the display character when
The television receiver further comprises a control circuit that always generates a display pulse even when the detection circuit detects an asynchronous signal.