JPH02256378A - Display switching circuit - Google Patents

Abstract

PURPOSE:To prevent display in mixture by suppressing a 2nd priority input signal for one screen display even after a control signal is not active when the priority input control signal is active even momentarily. CONSTITUTION:When, e. g. input series are 2 series, on priority input and other 2nd priority input exist, and each input has a display control signal 1 (2) and a display input signal 1 (2) and they are both inputted to an analog switch 1. A one field holding circuit 2 inputs a display control signal 1 and even when the display control signal 1 (priority input) changes from active into inactive state, the active state is kept for one field succeedingly. When the display control signal 1 is active, the priority input (display input signal 1) is kept selected for one field at minimum and the selection of the 2nd priority input is suppressed independently of the state of the display control signal 1 during that time. Thus, the display in mixture is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a switching circuit for a plurality of video input signals displayed on a television screen.

2. Description of the Related Art In conventional switching circuits, multiple input systems are switched using analog switches as shown in FIG. That is, the analog switch 10 has the display control signal 1 and display input signal 2, which are priority inputs, and the display control signal 2 and display input signal 2, which are priority input signals.
are input, and by display control signal 1,
The display control signals 1.2 and the display human input signals 1.2 are switched.

Problem to be Solved by the Invention With this circuit, if the display control signal 1 of the priority input (input signal 1) is switched frequently, the input signal 1 and input signal 2 displayed on the screen will be mixed and difficult to distinguish. The displayed content will be lost.

For example, every other character on the character screen displays a display input signal of 1.
If the display input signal 2 and the display input signal 2 are exchanged, it becomes impossible to read either information.

Means for Solving the Problems In order to solve the above problems, the present invention uses a display control signal for priority input, so that when the control signal for priority input becomes active even for an instant, the control signal becomes inactive. After at least one screen displays bones (
1 field) is for suppressing the clothing priority input signal.

Effect of the present invention With the above-described configuration, when there is a priority human input, even if the input is only in one part of the screen, the prioritized input is suppressed during that screen (in one field), thereby preventing the mixture of displays. It is possible to prevent

Embodiment FIG. 1 is a block diagram showing an embodiment of the switching circuit of the present invention. In Figure 1, there are two input series, one priority input and another prioritized input, and each input has a display control signal 1.2 and a display input signal 1.2. Both are input to analog switch 1. The holding circuit 2 for one field inputs the display control signal 1, and even if the display control signal 1 (priority input) changes from active to inactive,
This is a circuit that remains active during the field.

For example, a mono-multivibrator with a holding time of one field can be used.

As the switching control input signal, a signal obtained by holding the display control signal I and the display control signal L for one field is used. For this purpose, adder 3 is used.

The reason why the display control signal 1 itself is added in this way is to select the control signal 1 even when the display control signal 1 is always active.

As a result, when display control signal 1 becomes active, the priority input side (display input signal 1) remains selected for at least one field. Selection of priority input is suppressed.

In the embodiment, the holding time of the display control signal 1 is one field, but the holding time is not limited to this, and may be two fields, for example.

Effects of the Invention As described above, according to the present invention, it is possible to perform preferential selection and output of display manually without mixing on the screen with an extremely simple configuration, and it is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a display switching circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional display switching circuit. 1...Analog switch, 2...1 field protection circuit, 3...Adder. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 2

Claims (1)

[Claims] Input display input signals of two or more series and display control signals that control switching of display input signals, and any one series of display input signals has priority over display input signals of other series. A display switching circuit in which display input signals of one series invalidate display input signals of other series.