JPH0149234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a television receiver capable of receiving ordinary television signals and equipped with a video input terminal to which an external video signal is input.

Conventional configuration and its problems In a television receiver equipped with a video input terminal and an RGB input terminal, the video mode,
As a method for switching to RGB mode, for example, if there are three video inputs, there is a method of sequentially switching from TV to Video 1 to Video 2 to Video 3 to RGB to TV. This is convenient when operating with a remote control transmitter or the like.

However, with this method, when viewing the video 1 image, if you want to see a TV screen based on RF television signals (TV mode), video 2,
Video 3, I have to switch to RGB and sequential feed,
The disadvantage is that it is inconvenient.

Therefore, if you press the channel button on the television receiver, it will return to TV mode.
You can easily change to TV mode even if you are in any other mode, which is very convenient.

The above-mentioned conventional example will be explained below with reference to the drawings. FIG. 1 shows a circuit in which when the channel button of a television receiver is pressed, it returns to the television mode, no matter which mode it was previously in.

In FIG. 1, 1 is a counter, and when a mode switching pulse is input to a clock input terminal, a high level signal "H" is sequentially output to terminals . This high level “H”
The signal controls the mode switching of the screen. In the above-mentioned counter, the terminal is a reset terminal, and when a reset pulse is applied to this terminal, the counter is reset to television mode (terminal output "H").

The high-level "H" output terminals are sequentially switched by the mode switching pulse, but after switching sequentially from TV → Video 1 → Video 2 → Video 3 → RGB, if the next mode switching pulse is input again, the counter will start switching. 1 terminal becomes “H” level,
This "H" pulse is input to the reset terminal through the diode 4, and is reset to television mode (the terminal is at "H" level).

3 is a reset pulse generation circuit when the power is turned on, which generates a reset pulse when the power is turned on, and this pulse is applied to the reset terminal of the counter 1 through the diode 5. ) will start from.

2 is a pulse generation circuit when switching channels;
For example, use the AFC defective pulse when switching channels.

The pulses output from the pulse generation circuit 2 when switching channels are sent to the counter 1 through the diode 6.
is applied to the reset terminal of This resets the device to TV mode when the channel is changed, and returns to TV mode no matter what other mode it was in until then.

Now, some television receivers equipped with such an operation have a function of displaying a channel display number on-screen on a cathode ray tube screen. The display method is also such that the size of the channel display number is changed in three stages by a channel switching pulse generated when switching channels. That is, the letters are first displayed in uppercase, then medium, then lowercase, and finally disappear.

Also, when switching the screen mode, for example, RGB
When changing from TV mode to TV mode, the number of the selected channel is displayed in lowercase letters, and when changing from TV mode to Video 1 mode, the TV is configured to display "Video 1" in lowercase letters. A conventional example is a digital camera.

When a television receiver with such a function is reset from video mode to television mode by pressing the channel button, the microcomputer's discrimination operation first determines whether the channel has changed, and then when the mode has changed. In order to identify this, the channel number is displayed in uppercase letters on the cathode ray tube screen for a moment, and then in lowercase letters.
A problem arose in that it felt unnatural when viewed.

Purpose of the Invention The present invention solves the above-mentioned conventional problems and provides a television receiver in which the channel on-screen display starts from lowercase letters even when the channel button is pressed from video mode to reset to television mode. The purpose is to provide

Structure of the Invention When the television receiver according to the present invention is reset from the video mode to the television mode, the operation of the circuit that displays the channel number on-screen on the cathode ray tube screen is stopped for a certain period of time, and this certain period of time is first displayed. By setting the time to display the channel number in uppercase letters for a moment, you can eliminate the momentary display of the channel number in uppercase letters when resetting to TV mode, and make it possible to display the channel number in lowercase letters. can.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, the same parts as in FIG. 1 are given the same numbers and explained.

In FIG. 2, reference numeral 7 denotes an on-screen display circuit which generates necessary signals to display channel numbers, characters indicating other display modes, etc. on-screen on the cathode ray tube screen. The collector of the transistor 9 is connected to the blanking terminal 7a of the on-screen display circuit 7, and is configured so that no on-screen display is performed when the transistor 9 is turned on. Reference numeral 10 denotes a transistor, to the base of which a positive pulse output from the pulse generation circuit 2 is applied via a resistor 11 during channel switching. A load resistor is connected between the collector of the transistor 10 and the power supply terminal (12V), and a capacitor is connected between the collector and the ground.
3 are connected to each other. Further, the collector of the transistor 10 is connected to the base of a transistor 18 via a Zener diode 14. Here, 15 is the off-guarantee resistance of the transistor 18,
16 is a base resistance. The collector of the transistor 18 is connected to the anode of the diode 6 and the base of the transistor 9 via the resistor 8, respectively. 17 is a collector load resistance.

Next, the operation of the above configuration will be explained.
A pulse at the time of channel switching is applied to the base of the transistor 10 via the resistor 11. The pulse when switching channels is normally at “L” level.
Set to "H" level when switching channels. Therefore, normally the transistor 10 is off and its collector is at the "H" level, so the Zener diode 14 is conductive and the transistor 18 is turned on and the collector of the transistor 18 is at the "L" level. Therefore, transistor 9 is turned off and on-screen display circuit 7 operates.

On the other hand, during channel switching, since the channel switching pulse enters the base, the transistor 10 is turned on during that period, the charge stored in the capacitor 13 is discharged through the transistor 10, and the transistor 18 is turned off.

Next, when the channel switching pulse period ends, there is a delay by the charging time determined by the resistor 12 and capacitor 13 and the time until the Zener diode 14 becomes conductive, so the channel switching pulse is delayed by a certain period of time. The transistor 18 is turned on from off.

When transistor 18 is off, transistor 1
The collector of the transistor 8 becomes "H" level, and the transistor 9 is turned on for a certain period of time to blank the on-screen display and prevent the on-screen display from appearing.

Therefore, if you set this fixed time to the time during which the uppercase letters of the channel display are displayed momentarily at the beginning, even if the channel is changed from video mode and reset to TV mode, the on-screen display will remain capitalized for a moment. The channel can be displayed in lowercase letters without being displayed, and the initial purpose can be achieved. Due to this effect, the time for on-screen display of uppercase letters when switching channels in television mode is deleted, but this time is short compared to the period for displaying all uppercase letters, so there is no problem in practical use.

Effects of the Invention According to the present invention, when switching channels, the on-screen display circuit is blanked so that no on-screen display operation is performed for a certain period of time, so that the channel button can be operated from other modes. When the TV mode is reset to TV mode, the on-screen display does not momentarily display uppercase letters, but instead displays the channel in lowercase letters, so that it does not give an unnatural feeling to the viewer.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional television receiver, and FIG. 2 is a circuit diagram of a television receiver according to an embodiment of the present invention. 1...Counter, 2...Pulse generation circuit at channel switching, 3...Reset pulse generation circuit at power-on, 4, 5, 6...Diode, 7...On-screen display circuit, 7a...Blanking terminal, 8, 11, 16...Base resistance, 9, 10,
18... Transistor, 12, 17... Collector resistor, 13... Capacitor, 14... Zener diode, 15... Off-guarantee resistor.

Claims (1)

[Claims] 1 For television receivers equipped with multiple external input terminals, when switching channels, the channel display number is displayed on-screen in three stages: uppercase, middle, and lowercase, and when switching screen modes, it is displayed in lowercase. on-screen display means for displaying a mode display on the screen on the screen; a channel switching pulse generation circuit that generates a pulse when switching channels; and control means for stopping the display operation of the on-screen display means for a certain period of time, and canceling the stoppage of the operation of the on-screen display means when the certain period of time has elapsed.