JPH10312178A - Tv connection detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect its state in the state that a TV for home isn't connected and to inform it in the switching from a regular personal computer exclusive display to a domestic use TV display. SOLUTION: A TV connection detector detecting connection with a domestic use TV 7 is provided with a video signal output means 1 encoding to an analog signal, a video signal input means 2 inputting a video signal while displaying on the domestic use TV 7, a video signal detection means 3 detecting that a video signal is inputted from the video signal input means 2 and a coincidence detection means 4 detecting a signal difference between the video signal from the video signal input means 2 and the video signal from the video signal output means 1. Further, when the noncoincidence is detected by the coincidence detection means 4, a video selection switch is switched from the video signal output means 1 to the personal computer exclusive display 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television connection detection device built in or external to a personal computer (personal computer), and more particularly to a video signal output to a home television (a television capable of selectively displaying a plurality of video signals including a monitor). When,
The present invention relates to a television connection detection device that detects a home television connection by comparing video signal inputs from the home television.

[0002]

2. Description of the Related Art In recent years, when an image signal created by a personal computer is displayed on a display dedicated to the personal computer, the horizontal synchronization frequency is set to 30 kHz to 61 kHz and the vertical synchronization frequency is set to 50 kHz.
１００100 Hz to provide an automatic tracking frequency characteristic, the scanning method is non-interlaced, and the resolution is 640 × 48
0,800 × 600, 1024 × 768, which are increasingly displayed with higher resolution. However, with the recent development of televisions that connect ordinary household televisions to the Internet, personal computers that can output not only displays dedicated to personal computers but also general televisions are being developed.

[0003] On the other hand, a conventional personal computer also has a function of displaying on a normal dedicated display and a function of displaying on a home television, but cannot display simultaneously, and when one is displayed. , The other is not displayed, and each is exclusively switched and displayed, and all the switching operations are left to the operator.

[0004]

[0005] However, the function of displaying on a normal personal computer display or monitor,
Since the functions displayed on the home TV cannot be displayed at the same time, they are exclusively switched and displayed, so if you switch to the home TV display while the home TV is not connected, the PC screen will display Computer cannot recognize that the home TV is not connected.
If you switch to a home TV while the home TV is not connected, you will not be able to display the PC screen, and if you try to switch to the normal PC display, you will not be able to display the PC screen. It was in a state that did not exist.

[Object of the Invention] An object of the present invention is to provide a method for switching from a display dedicated to a personal computer display to a home television display.
The purpose is to detect and notify the state.

[0006]

SUMMARY OF THE INVENTION The present invention has a video output circuit for outputting a personal computer screen to a home television, and a video input circuit for receiving an output signal from the home television. And a video signal detection circuit for detecting that a video input signal is input, and compares and detects a video output signal output from the apparatus and a signal output from a home television and input to the apparatus. It has a coincidence detection circuit and has a function of notifying the CPU of a result of the comparison.

Specifically, in a television connection detecting device for detecting connection with a home television, a video signal output means for encoding into an analog signal, and a video signal input for inputting a video signal being displayed on the home television. Means,
A video signal detecting means for detecting that the video signal is input from the video signal input means, and a signal difference between a video signal from the video signal input means and a video signal from the video signal output means. It is characterized by having coincidence detecting means.

In the above-mentioned television connection detecting device,
When the coincidence detection means matches the video signal from the video signal input means with the video signal from the video signal output means, the apparatus further comprises means for notifying a CPU. Further, when the match is not detected by the match detecting means, the connection of the video selection switch to the video signal output means is switched to the connection of the dedicated display.

[Operation] Whether or not a home television is connected can be confirmed by inputting a video output signal from a video output terminal provided in the home television.

Further, by comparing the video output signal from the home television with the signal output from the personal computer, it is possible to confirm whether or not the screen from the personal computer is displayed. By this confirmation, when a home TV is connected, the video selection of the home TV is switched to the image from the PC as the video mode, and when the home TV is not connected, it is displayed on the PC dedicated display. become able to.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings.

[1] Description of Configuration In the embodiment of the present invention shown in FIG. 1, a video signal output circuit 1 for outputting a personal computer screen to a home television 7 and a signal output from the home television 7 are inputted. A video signal input circuit 2 for detecting the input of a video input signal from the home television 7;
A match detection circuit 4 for detecting that the signal output from the video signal output circuit 1 and the signal input to the video signal input circuit 2 are the same signal, and a notification signal to the CPU 6 for notifying the CPU 6 when they match. And 5. If they do not match, the video output selection switch 9 of the personal computer is switched according to the notification signal 5, and the personal computer display 8 is switched.
To display the image signal of the personal computer.

Here, the home television 7 has a video input terminal for inputting an image signal from a personal computer, and has a video output terminal for video outputting an image signal being displayed on the CRT of the home television 7. When a television broadcast is received by the home television 7, an image signal of the television broadcast is output to a video output terminal and used for VTR recording. Also, the personal computer does not output an image signal to the home television 7 while displaying on the personal computer display 8,
When an image signal is being output to the home television 7, the image signal cannot be output to the personal computer display 8. Therefore, when a television broadcast is received by the home television 7 connected to the video output terminal of the personal computer, no image signal generated in the personal computer is displayed.

The configuration will be further described in detail. The embodiment shown in FIG. 1 includes a video signal output circuit 1 for encoding a digital signal of a personal computer screen into an NTSC signal so as to output the personal computer screen to a home television 7, and a home television 7.
A video signal input circuit 2 for inputting a signal to output screen information currently displayed on the home television 7 as an NTSC signal from a video output terminal of the home television 7 and decoding it into a digital signal that can be handled by a personal computer; A video signal detection circuit 3 for detecting that a video input signal is input, a signal output from the video signal output circuit 1 and a signal input to the video signal input circuit 2 are detected as the same signal And a notification signal 5 to the CPU 6 for notifying the CPU 6 when the match is detected by the match detection circuit 4.

Here, when the match is detected by the match detection circuit 4, it is determined that the video output terminal of the personal computer is connected to the home television 7, and for example, the home television 7 receiving television broadcasts is determined. Is switched to the video mode, and the image signal of the personal computer is displayed on the home television 7. On the other hand, if the coincidence is not detected by the coincidence detection circuit 4, it is determined that the home television 7 is not connected, and the video output selection switch 9 of the personal computer is switched to display the image signal of the personal computer on the display 8 for exclusive use of the personal computer. I do.

[2] Description of Operation Next, the operation of the block diagram of FIG. 1 will be described with reference to the drawings. Personal computer CPU as this TV connection detection device
The digital image signal from 6 is a video output selection switch 9
Digital image signal displayed on the computer screen via NT
Video signal output circuit 1 for encoding to SC signal 81
Thus, the output signal is input to the home television 7 and the output NTSC signal 82 being displayed from the home television 7 is input to the video signal input circuit 2 for decoding into a digital signal. The video signal input circuit 2 is provided with an AGC circuit for matching the level with the video signal output circuit 1.

The video signal detection circuit 3 includes a home television 7
That the NTSC signal 82 from the
It is detected based on the presence or absence of the C signal 82, and if detected, sent to the coincidence detection circuit 4.

The coincidence detecting circuit 3 includes a television signal output circuit 1
And the signal of the video signal input circuit 2 are compared and detected. The coincidence detection circuit 3 compares the difference of the luminance signal among the video signals in one horizontal period or one field period, and if the accumulated value is within a predetermined range, the two signals match. Judge.

The signal output from the apparatus and the signal input from the home television 7 are compared, and when they match, the matching information is notified as a notification signal 5 to the CPU 6. By notifying, the CPU 6 determines whether the NTSC signal 81 output to the home television 7 and the NTSC signal 82 input from the home television 7 are the same or the same signal is input. Can be recognized. CPU
6 switches the video output selection switch 9 by recognizing that the signal is different from the signal output to the home television 7, stops the output to the home television 7, and switches to the normal personal computer display 8. Can be displayed.

[0020]

According to the effect of the present invention, when the television is not connected, the display can be switched to the ordinary personal computer display without the intervention of the operator, thereby preventing the operator from operating.

The reason is that it is possible to recognize whether or not the television is displaying the screen of the apparatus without the intervention of an operator.

[Brief description of the drawings]

FIG. 1 is a block diagram of a television detection device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Video signal output circuit 2 Video signal input circuit 3 Video signal detection circuit 4 Match detection circuit 5 Notification signal to CPU 6 CPU 7 Television 81 Output NTSC signal 82 Input NTSC signal

Claims (3)

[Claims] 1. A television connection detecting device for detecting connection with a home television, a video signal output means for encoding an analog signal, a video signal input means for inputting a video signal being displayed on the home television, A video signal detecting means for detecting that the video signal is input from the video signal input means, and a signal difference between a video signal from the video signal input means and a video signal from the video signal output means. A television connection detecting device comprising a coincidence detecting means. 2. The television connection detecting device according to claim 1, wherein when the video signal from the video signal input unit matches the video signal from the video signal output unit by the coincidence detecting unit, the CPU is notified. A television connection detection device, comprising: 3. The television connection detecting device according to claim 1, wherein when the coincidence is not detected by the coincidence detecting unit, a video selection switch switches a connection to the video signal output unit to a connection of a dedicated display. Characteristic television connection detection device.