Automatic switching method for signal source channel of video frequency display equipment
A video display and automatic switching technology, which is applied to color TV parts, TV system parts, TVs, etc., can solve problems such as troublesome, unhumanized, and video display devices that cannot be automatically switched accordingly, and achieve exemption The effect of manual operation
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Embodiment 1
[0031] Example 1. A method for automatically switching signal source channels of a video display device, as shown in FIG. 1 . It includes the following steps:
[0032] (1) The CPU is powerful and can directly identify the video signal. The video signal is directly blocked from the input end of the signal through a coupling capacitor, and then impedance-matched and divided to the control pin of the CPU through a resistor to realize the control of the CPU;
[0033] (2) Design a program module embedded in the software system of the whole machine, define the audio and video channels according to the number of audio and video channels, such as AV1, AV2...AVn, etc., and according to the control management that the CPU can provide pins, which are defined as the automatic identification control pins of AVn one by one. If the control pins that the CPU can provide are less than the number of audio and video channels, a relatively important channel is selected for automatic control;
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Embodiment 2
[0052] Example 2. A method for automatically switching signal source channels of a video display device, as shown in FIGS. 1-2 . Add a video signal monitoring circuit between the video input circuit and the control pin of the CPU,
[0053] In the step (1), when the CPU cannot directly recognize the video signal, the video signal SIGNAL is blocked by the coupling capacitor C1 and impedance matched by the resistor R1, and then processed by the synchronous separation circuit (consisting of the triode V1 and its peripheral devices), Output a video synchronization signal with a certain amplitude. The amplitude of the synchronization signal must reach a certain level. There are two main reasons for this: one is to effectively control the action of the CPU, and the other is to avoid misoperation caused by stray interference. This synchronization signal is connected to the control pin of the CPU as a control input signal, and the CPU realizes the operation function of the software b...
Embodiment 3
[0056] Example 3. A method for automatically switching signal source channels of a video display device, as shown in Fig. 1 and Fig. 3 .
[0057] In the step (1), when the CPU can only identify high and low levels, it is necessary to add a synchronous separation circuit and a DC voltage control circuit to convert the synchronous signal into a stable DC voltage as the control signal of the CPU control pin. Same as the requirements of embodiment 2, the DC level must reach a certain level, and the CPU realizes the operation function of the software by judging the level of the input pin.
[0058] That is to say, if the CPU of a video display device can only recognize high and low levels, that is, when the CPU can only be controlled by the level of a stable DC voltage, a synchronous separation circuit and a DC voltage control circuit need to be added. In this case, it is necessary to convert the synchronous signal into a stable DC voltage as the control signal of the CPU control p...
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