JPH04239885A - Video switching device and special effect switching circuit used therefor - Google Patents

Abstract

PURPOSE:To inexpensively and efficiently realize a video switching device to execute the inserting and the switching of a video signal by special effect and to obtain a suitable special effect switching circuit used for the switching device. CONSTITUTION:A constitution is made to convert the sub-video signal from a computer 21 into the signal of a form able to be inserted into the one part of a main video signal by a scanning converting circuit 23 and to control the effect switching starting operation of a special effect switching circuit 28 and the output operation of a key signal for inserting the sub-video signal supplied from the above mentioned scanning converting circuit 23 to the said circuit 28 by the above mentioned computer 21. Besides, the above mentioned special effect switching circuit 28 is the constitution that effect switching is executed only for a sub-video signal period at the inserting of the above mentioned sub- video signal to the main video signal.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video switching device that mixes and switches various video signals for display, and a special effect switching circuit used therein.

0002

2. Description of the Related Art Some video devices incorporate a sub-picture signal into a part of a main video signal, and further perform the incorporation by using special effect switching such as dissolve or wipe. For example, as shown in FIG. 4, sub-images gradually appear on a screen containing only the main image, or vice versa.

[0003] When realizing such a function, conventionally,
As shown in FIG. 5, the first and second video signal mixing circuits (1
) (2) is provided, and one of the two gain control circuits (3) and (4) in the first video signal mixing circuit (1) to which the sub-video signal is inputted, the control signal (3) shown in FIG. b) is applied,
By applying a control signal (b) to the other (4) to which the main video signal is input, and by combining the output signals of each gain control circuit (3) and (4) in an adder circuit (5), the main video signal is first input. Create a signal with a sub-video signal inserted into the signal. and two gain control circuits (6) of the second video signal mixing circuit (2).
The first synthesized signal of (7) is input, while (6
), the control signal (c) in Figure 7 is applied to the other (7) to which the main video signal is applied as is, and the control signal (d) is applied to the other gain control circuit (c) and (d). By combining the output signals in an adder circuit (8), the main video signal into which the sub video signal has been inserted gradually replaces the original main video signal itself, thereby performing the above-described dissolve operation. .

[0004] Furthermore, when displaying a video signal from a personal computer by embedding it into a video signal from a VTR or the like using a circuit with such a configuration, conventionally, in addition to the personal computer as the video signal source, another personal computer or a dedicated Each of the above circuits was controlled by hardware.

[0005]

[Problems to be Solved by the Invention] However, when switching special effects such as dissolve using the configuration shown in FIG. Since the video signal passes through two video signal mixing circuits (1) and (2), deterioration of the video signal in these video signal mixing circuits cannot be denied.

[0006] Furthermore, providing control hardware separately in addition to the personal computer as a video signal source has the problem of complicating the device configuration of the entire video display system and increasing costs.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a video switching device that uses a personal computer or various video playback devices as a video signal source and can efficiently and inexpensively implement video inset and switching using special effects with a relatively simple configuration. This is the first purpose.

[0008] A second object of the present invention is to realize a special effect switching circuit used in the video display device with a configuration that can suppress the deterioration of the video signal as much as possible. purpose.

[0009]

[Means for Solving the Problems] The video switching device of the present invention includes a computer that is also used as a video signal source, and a main video signal that is separately inputted with a sub-video signal from the computer or another video signal source. a scan conversion circuit that converts the signal into a format that can be inserted into a part of the main video signal; and a special effect switch that inserts the sub video signal into a part of the main video signal using a special effect and outputs it using a key signal output from the scan conversion circuit. A key signal output operation of the scan conversion circuit and an effect switching start operation of the special effect switching circuit are controlled by the computer.

Further, the special effect switching circuit of the present invention includes a first and second gain control circuit to which a main video signal and a sub-picture signal are inputted, respectively, and an adder circuit for synthesizing their respective output signals. a video signal mixing circuit for inserting and outputting a sub-picture signal into the sub-picture signal; a control signal generating circuit for producing first and second variable control signals respectively supplied to the first and second gain control circuits; and a control signal generating circuit for producing the sub-picture signal. and supplying the first and second variable control signals to the first and second gain control circuits only during the period of the sub-picture signal;
A switching circuit is provided which supplies first and second fixed control signals for controlling to cut at least the sub-video signal to the first and second gain control circuits during other periods, and the output signal of the video signal mixing circuit is displayed as a video. By supplying the sub-picture signal to the sub-picture signal, the effect is switched only to the sub-picture signal.

[0011]

[Operation] According to the video switching device of the present invention, the host computer is used as a signal source of the sub-picture signal inserted into a part of the main video signal, and the scan conversion circuit and special effect switching circuit operate. control.

According to the special effect switching circuit of the present invention, the video signal mixing circuit changes the gain of the main video signal and the sub video signal only during the sub video signal period, thereby changing the sub video signal by effect switching. It is inserted into the main video signal.

[0013]

[Embodiment] FIG. 1 shows an embodiment of the special effect switching circuit of the present application, and this circuit can be roughly divided into control signal generation circuits (1
0), a switching circuit (11), and a video signal mixing circuit (12).
).

The control signal generating circuit (10) includes a constant voltage source (13) and a terminal (T1) using this constant voltage source as a power source.
(A) in FIG. 6 from the time of the effect switching signal applied to
A lamp voltage generation circuit (1) that generates a lamp voltage such as
4) and its lamp voltage (A) from the constant voltage of the constant voltage source described above, the lamp voltage with complementary characteristics (Fig. 6
The lamp voltages (a) and (b) are input to the switching circuit (11) as first and second variable control signals. The lamp voltage generation circuit (14) includes, for example, a capacitor (14b) charged from the constant voltage source via a constant current circuit (14a) as shown in FIG. 2, and a normally closed switch that is opened by the effect switching signal. (14c), a buffer amplifier (14d), etc.

On the other hand, the switching circuit (11)
A first changeover switch (16) in which a variable control signal (a) is applied to one input terminal and the other input terminal is grounded, and a second variable control signal (b) is applied to one input terminal and the other input terminal is grounded. a second changeover switch (17) whose terminal is given a constant voltage from the constant voltage source (13) as a fixed control signal;
, and each switch (16) (17) is connected to a terminal (T2
) The state shown in the figure is switched only during the period of the sub-picture signal by a key signal to be described later.

[0016] Furthermore, the video signal mixing circuit (12) includes:
The sub-picture signal input through the terminal (T3) is
A first gain control circuit (18) that controls the gain according to a control signal from the output terminal of the changeover switch (16), and a terminal (T
a second gain control circuit (19) that controls the gain of the main video signal input via the main video signal input via the second changeover switch (17) according to a control signal from the output terminal of the second changeover switch (17); 18) Combine the output signals of (19) and output the output terminal (T
5) and an adder circuit (20).

Now, in such a configuration, the first and second gain control circuits (18) and (19) both have a gain of zero when the control signal applied thereto is the minimum, and when the control signal is the maximum. Since the gain is controlled to be maximum when
During the sub-video signal period when the second changeover switch (16) (17) is switched to the illustrated position, the first and second gain control circuit (18)
By applying the aforementioned first and second variable control signals (a) and (b) to (19), respectively, the first gain control circuit (1
The sub-video signal output from 8) gradually increases,
In contrast, the main video signal output from the second gain control circuit (19) gradually decreases.

On the other hand, in periods other than the sub-video signal period, the first and second
Since the changeover switches (16) and (17) are set to the opposite positions as shown in the figure, the first gain control circuit (18) is applied with a fixed control signal at the ground level and has a gain of zero, so that the sub-picture signal is not output. In contrast, the second gain control circuit (19) to which the maximum level fixed control signal is applied outputs the main video signal in the maximum gain state.

Therefore, the output signal of the adder circuit (20) for synthesizing the main and sub-video signals is sent to the display device (
(not shown), an image in which the sub-screen gradually appears in the main screen due to the dissolve effect as shown in FIG. 4 can be realized.

Next, FIG. 3 shows an embodiment of a video switching device using the special effect switching circuit of FIG. 1 described above.

In FIG. 3, (21) is a host computer consisting of a personal computer which is also used as a video signal source;
(22) is an NTSC video signal source such as a VHS VTR, and (23) is a sub video signal in a format that allows the video signal from the computer or NTSC video signal source to be inserted into a part of the main video signal in high-definition format. The scanning conversion circuits (24), (25), and (26) are HD-VTR and HD
- first, second, and third high-definition video signal sources as main video signal sources consisting of a VDP (video disc player), etc.; these are video signal sources (24) to (26) and the scan conversion circuit (23); The output high-definition video signal is input to a video signal selection circuit (27) in the form of a matrix switch circuit.

The video signal selection circuit (27) is selectively operated by the computer (21) and selects three signals from the first to third high-definition video signal sources (24) to (26).
One of the types of main video signals is led out to one output terminal (T7), and a sub-picture signal from the scan conversion circuit (23) is led out to the other output terminal (T6). The main and sub-video signals derived in this way are input to terminals (T4) and (T3) of the special effect switching circuit (28), respectively.

The special effect switching circuit (28) is shown in FIG.
The circuit shown in FIG. 1 is the circuit shown in FIG.
) The aforementioned effect switching signal applied to the lamp voltage generation circuit (10) is output from the computer (21), and is synchronized with the sub-video signal applied to the switching circuit (11) via the terminal (T2). The key signal is outputted from the scan conversion circuit (23) described above.

With this configuration, the computer (21) can be used not only as a video signal source but also for system control of the entire video switching device including the special effects switching circuit (28). Moreover, when the sub screen is not inserted into the main screen, the key signal output to the switching circuit (11) is stopped and the first and second switches (16) (17) (Fig. 1 ) in the state shown in the figure, and connect any two of the first to third high-definition video signal sources (24) to (26) to the output terminals (T6) (T7) of the video signal selection circuit (27). By deriving the video signal, it is possible to switch between the two video signals using a dissolve effect.

In both the embodiments shown in FIGS. 1 and 3, video signals are switched by the dissolve effect, but the characteristics of the first and second variable control signals output from the control signal generation circuit (10) are changed. By doing so, it is also possible to configure the video signal to be switched using other special effects such as wiping or scrolling.

Furthermore, although the main video signal has been explained using a high-definition signal as an example, it is of course possible to use a normal television signal such as an NTSC signal.

[0027]

Effects of the Invention According to the video switching device of the present invention, the video switching device has a function of fitting and switching video signals using special effects, and can easily switch these functions. It can be realized efficiently and inexpensively with a simple configuration.

Furthermore, according to the special effect switching circuit of the present invention, in order to realize the function of merging the sub-picture signal into the main video signal by switching the special effect, a plurality of video signal mixing circuits are conventionally used. Since only one circuit is required,
Deterioration of the video signal caused by these video signal mixing circuits can be suppressed, and therefore it is suitable for use in a video switching device that handles high-frequency signals such as high-definition signals.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing one embodiment of a special effect switching circuit of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration of its main parts.

FIG. 3 is a circuit block diagram showing an embodiment of the video switching device of the present invention.

FIG. 4 is a diagram illustrating fitting of a sub-screen into the main screen by a dissolve effect.

FIG. 5 is a circuit block diagram showing a conventional example of a special effect switching circuit.

FIG. 6 is a diagram showing a key signal for sub-screen embedding.

FIG. 7 is a diagram showing first and second variable control signals.

[Explanation of symbols]

10 Control signal generation circuit 11 Switching circuit 12 Video signal mixing circuit 28 Special effect switching circuit

Claims (2)

[Claims] 1. A computer that is also used as a video signal source, and a scanning device that converts a sub-video signal from the computer or other video signal source into a signal in a format that can be inserted into a part of a separately input main video signal. a conversion circuit; and a special effect switching circuit that inserts and outputs the sub-picture signal into a part of the main video signal using a special effect according to a key signal output from the scan conversion circuit, A video switching device characterized in that a signal output operation and an effect switching start operation of the special effect switching circuit are controlled by the computer. Claim 2: Consists of a first and second gain control circuit into which a main video signal and a sub-video signal are respectively input, and an adder circuit that synthesizes the respective output signals, and inserts the sub-video signal into a part of the main video signal. a video signal mixing circuit that outputs a video signal;
a control signal generation circuit that generates first and second variable control signals respectively supplied to a second gain control circuit; and a control signal generation circuit that is switched in response to a key signal synchronized with the sub-video signal, and that is switched only during the period of the sub-video signal. the first and second variable control signals to the first and second variable control signals;
a switching circuit that supplies first and second fixed control signals to the gain control circuit and controls to cut at least the sub-video signal during other periods; A special effect switching circuit configured to switch effects only on the sub-video signal by supplying an output signal of the circuit to a video display section.