JPS61195092A - Signal inserting device - Google Patents

Abstract

PURPOSE:To eliminate the breakdown of a character and a graphic and a color oozing by eliminating a period that inserts the signal of the character and the graphic and chrominance components to a composite video signal. CONSTITUTION:The composite video signal is inputted to a terminal 1 and is separated to a luminance signal and the chrominance components at an isolation circuit 7. The separated luminance signal is supplied to a clipping circuit 3 after clamping by a clamping circuit 2. The base of a transistor Q2 is connected to a voltage source V1 through a switch S1 that is opened/closed by a control signal supplied at terminal 4 and the luminance signal that is clipped only within a period when the terminal 4 is at 'H' level is transmitted to a synthesizing circuit 9. On the other hand, the chrominance component that are separated at the isolation circuit 7 are transmitted to the synthesizing circuit 9 only when the terminal 4 is at 'L' level through a switch 8 that is opened/closed by a control signal supplied at the terminal 4. As stated above, by separating the composite video signal to the luminance signal and the chrominance components and by eliminating the chrominance components during the period that the signal of the character the graphic is inserted to the luminance signal, the breakdown of a part where a white character or the graphic can be seen on a television screen and the color oozing at the vicinity thereof are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a signal insertion device for inserting white characters and figures into a composite video signal used in magnetic recording and reproducing devices, television devices, and the like.

2. Description of the Related Art In recent years, signal insertion devices have come into widespread use due to the spread of small VTRs. An example of a conventional signal insertion device will be described below with reference to the drawings.

In FIG. 2, 1 is a first input terminal, 2 is a clamp circuit, 3 is a clip circuit, 4 is a second input terminal, 5 is a power supply terminal, and 6 is an output terminal. A composite video signal is applied to a first input terminal 1, and is supplied to a clipping circuit 3 in which the voltage at the tip of the synchronizing signal is clamped by a clamping circuit 2. The clip circuit 3 includes transistors Q1. Q2, a voltage source 1, and a switch S1, the base of the transistor Q1 is supplied with the output of the clamp circuit 2, and the base of the transistor Q2 is connected to the second input terminal 4.
A voltage source v1 is connected through a switch S1 which is opened and closed by a control signal supplied to the switch S1. Transistor Q1
．． The collectors of Q2 are both connected to power supply terminal 5, and the emitters of transistors Q+ and Q2 are both grounded via current source 1 and connected to output terminal 6.

In a signal insertion device having such a configuration, a composite video signal as shown in FIG. 3A is supplied to the first input terminal 1,
When a control signal as shown in FIG. 3B is supplied to the second input terminal 4, the switch s1 is closed only while the second input terminal 4 is at the "H" level, and the base potential of the transistor Q2 is set to the voltage source The output voltage becomes 1, and the output voltage at output terminal 6 is shown as C in Figure 3.
V-V only during the period when the second input terminal 4 is at high level as shown in
A signal clipped to a potential of l-V@E2 can be obtained.

(However, Va t 2 is the base of transistor Q2,
is the emitter voltage. ) That is, the second input terminal 4
By means of a control signal supplied to the first input terminal 1, characters or figures that appear white on the television screen can be inserted into the composite video signal supplied to the first input terminal 1.

Problems to be Solved by the Invention In such a conventional configuration, since the signal input to the first input terminal 1 is a composite video signal, the color signal, which is one of the signals making up this composite video signal, is , the second input terminal is “
A small amount is output even at H'' level. This is thought to be because the frequency of the color signal is higher than the frequency of the luminance signal.For this reason, blurring occurs in areas where white characters or graphics are visible on the television screen. There was also the drawback that color bleeding occurred in the vicinity of the color bleeding.

An object of the present invention is to provide a signal insertion device that can eliminate blurring and color bleeding.

Means for Solving the Problems The signal insertion device of the present invention is configured to insert a character or graphic signal into a luminance signal separated from a composite video signal, and during the insertion period, the signal insertion device inserts a character or graphic signal into a luminance signal separated from a composite video signal. The present invention is characterized in that it is configured to output a signal from which the signal has been removed.

Function: With this configuration, the color signal is removed during the period when character and graphic signals are inserted into the composite video signal, so blurring and color bleeding can be eliminated.

Example An embodiment of the present invention will be described below with reference to FIG.

Components having the same functions as those in FIG. 2 are given the same reference numerals and their explanations will be omitted. 7 is a separation circuit that separates a composite video signal into a luminance signal and a chrominance signal from a composite video signal in which a luminance signal of a low carrier FM signal and a low-frequency conversion chrominance signal are superimposed; 8 is a second input terminal 4
A switch 9 opens and closes according to a control signal supplied to the switch 9. A switch 9 is a synthesis circuit that synthesizes a luminance signal and a color signal to produce a composite video signal.

Next, the configuration of FIG. 1 will be explained in detail based on the operation. A composite video signal is input to the first input terminal 1, and the separation circuit 7
The signal is separated into a luminance signal and a color signal. The separated luminance signal is clamped by a clamp circuit 2 and then supplied to a clip circuit 3.

A voltage source v1 is connected to the base of the transistor Q2 via a switch S1 which is opened by a control signal supplied to the second input terminal 4. Therefore, the luminance signal clipped to the potential V-Vl-V-ε2 only during the period when the second input terminal 4 is at the "HII level" is sent to the synthesis circuit 9. Voltage).

On the other hand, the color signal separated by the separation circuit 7 is sent to a switch 8 which is opened and closed by a control signal supplied to the second input terminal 4.
The signal is sent to the synthesis circuit 9 only when the second input terminal 4 is at the "L" level. The luminance signal and color signal sent to the combining circuit 9 are combined and outputted to the output terminal 6 as a composite video signal.

As described above, according to this embodiment, a composite video signal is separated into a luminance signal and a color signal, and the color signal is removed during the period in which a character or graphic signal is inserted into the luminance signal, so that the television screen It is possible to eliminate blurring in areas where white characters or figures are visible on the screen and color bleeding in the vicinity.

Effects of the Invention As described above, the signal insertion device of the present invention is configured to insert a character or graphic signal into a luminance signal separated from a composite video signal, and also inserts a color signal in the composite video signal during the insertion period. Since the configuration was configured to output a signal with the removed
It is possible to obtain excellent effects such as eliminating blurring in areas where white characters or figures are visible on a television screen and color bleeding in the vicinity.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional signal insertion vjL arrangement, and FIG. 3 is an explanatory diagram of the operation of FIG. 2.

Claims (1)

[Claims] 1. A signal insertion device configured to insert a character or graphic signal into a luminance signal separated from a composite video signal, and output a signal from which a color signal in the composite video signal has been removed during this insertion period.