JPS58151177A - Shadow key signal generator - Google Patents

Abstract

PURPOSE:To eliminate the need for the delay of a super input signal in many bits in inserting the super input signal as the super and without shift in the position of the super input signal down right, even if a wider shadow is generated, by generating the shadow with the field loop. CONSTITUTION:The level of the super input signal applied to an input terminal 1 is compared with that of a shadow key signal being a field feedback signal at an NAM circuit 2, the higher level is selected and outputted to a level control circuit 3 and a shadow key signal conversion circuit 6. The level control circuit 3 performs the level control of the field feedback circuit and makes the gain as <=1. The shadow key signal level-controlled is widened by upper and lower one line each vertically at a shadow key generating circuit 5 and by left and right for about one line each horizontally. The width of the shadow key signal is widened by controlling the field feedback gain, and only key signals exist in the field loop, then 4-bit is enough, allowing to obtain a wider shadow key signal with a smaller circuit constitution than conventional systems.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shadow key signal generator used when inserting a super signal such as text into a base video signal in television broadcasting.

Conventionally, when inserting a super signal into a base video signal, a method has been used to make the super signal easier to see by lowering the level or coloring the vertical and horizontal peripheral parts of the inserted super signal to create a shadow. ing. In this case, to insert a super signal with a shadow that lowers the level around the super signal into the base video signal, generate a shadow key signal that is wider in the vertical and horizontal directions than the super signal, and use this. This can be achieved with a device that attenuates the level of the base video signal and adds the super signal.

In order to generate a shadow key signal that is wider in the vertical and horizontal directions than the super signal, conventional digital methods delay the signal by several lines in the vertical direction, mix the delayed signals for each line, and then By obtaining a wide shadow key signal, delaying it horizontally by several clocks, and mixing it with a NAM (non-additive mix) circuit that selects and outputs the higher delayed signal level for each clock. I was getting it.

In the figure, a is a super signal, b, c is a signal obtained by delaying the bus-bar signal, and d is a shadow key signal obtained by mixing the signals of a''-C in a NAM circuit.

However, if the width of the shadow key signal is increased, the center point of the shadow key signal will shift to the lower right on the screen.

To prevent this, it is possible to use a frame memory to advance the super signal to the upper left in advance. However, in order to make the super signal an NTSC color signal and insert that color signal as a super signal into the base video signal, the color super signal must be delayed in the frame memory, so the frame memory must be at least 8 bits. It is. Furthermore, increasing the width of the shadow key signal requires a large number of NAM circuits, which has the disadvantage of increasing the scale of the circuit. The present invention aims to eliminate these drawbacks and provide a shadow key signal generator capable of performing a variety of super insertions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below using one embodiment thereof with reference to the drawings.

In Fig. 2, 1 is the input terminal of the super human power signal, 2
is a NAM that compares the A-talkie signal and the super human signal, which will be described later, and selects and outputs the one with the higher level.
(non-additive mix) circuit, 3 is a shadow key signal level control circuit, 41d frame memory,
6 is a shadow key signal generation circuit that widens the width of the shadow key signal in the vertical and horizontal directions, 6 is a shadow key signal conversion circuit that converts the waveform of the shadow key signal, and 7 is a level comparison circuit between the super human signal and the shadow key signal. , a NAM circuit which selects and outputs the one with the higher level, and 8 is a shadow key signal output terminal.

Next, the operation of this embodiment will be explained. The super human power signal supplied to the input terminal 1 is compared in level with a chateau key signal, which is a field feedback signal described later, in the NAM circuit 2, and the one with the higher level is selected and sent to the level control circuit 3 and the shadow key signal conversion circuit 6. Output. The level control circuit 3 controls the level of the field feedback circuit, and has a gain of 1 or less. The level-controlled shadow key signal is sent vertically upward by the shadow key generation circuit 6.
Widen the bottom line one by one, and then expand the horizontal and vertical lines by the same width to the left and right.

For example, in the vertical direction, three signals whose phases differ by exactly one line are each NAMed.
It can be synthesized using a circuit. Also, the movement is as good in the horizontal direction as in the vertical direction.

The shadow key signal whose width has been expanded in this way and the super human signal are mixed in the NAM circuit 2, and the shadow key signal is field-feedback using a field delay device consisting of a level control circuit 3 and a frame memory 4. As the number of feedbacks increases, the width of the shadow key signal increases (9), and the amount of expansion is controlled by the gain control of the level control circuit 3. Field feedback gain is 1
When close to , the width of the shadow key signal is wide, and when the field feedback gain is zero, the shadow key signal has the same width as the super human signal. By controlling the field feedback gain in this way, the width of the shadow key signal can be varied, and since the field loop is only the key signal, it only requires about 4 bits, making it possible to obtain a wider shadow key signal with a smaller circuit configuration than before. I can do things.

If the center of the returned shadow signal is in phase with the super human signal in the vertical and horizontal directions, a shadow can be generated around the super human signal.
If the phase is shifted, it can be shifted to the upper right, as shown in FIG. 3, for example.

In addition, in order to obtain the effect shown in Fig. 3, the phase of the field-returned shadow key signal must be the same as that of the super human power signal, and the shadow key generation circuit 5 must prohibit widening to the left and bottom, and Only the upper side may be made wider.

This shadow key signal is generated by feedback with a field feedback gain of 1 or less, so as shown in Figure 4, compared to the super human signal a, the more the number of returns, the lower the level as shown in b. This is achieved by converting the waveform as shown in C'%-e using a shadow key signal conversion circuit that can be easily implemented using ROM (read only memory), etc., and combining this waveform-converted signal with the super human input signal using the NAM circuit 7. You can create a variety of shadow supers that you have never seen before.

As explained above, the present invention generates shadows using field loops, so even if a wide shadow is generated, the position of the super human signal does not shift to the lower right, and the super human signal is inserted as a super signal. When doing so, there is no need to delay the super human power signal with multiple pits. Field memory still involves signal processing, so the number of bits is small, so even if a wide shadow is generated, it can be achieved with a small-scale circuit, and various shadow supers can be performed, so its industrial value is enormous.

[Brief explanation of drawings]

Figure 1 is a diagram that is wider horizontally than the super signal, Figure 2
FIG. 3 is a block diagram showing the configuration of a shadow key signal generator in an embodiment of the present invention, FIG. 3 is an explanatory diagram showing an example of the shadow key, and FIG. 4 is a signal waveform diagram of the main part. 1... Super human power signal input terminal, 2...
... NAM circuit, 3 ... Level control circuit, 4
...Frame memory, 5...Shadow key signal generation circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A shadow key signal generation circuit that generates a shadow key signal that expands the vertical and horizontal periphery of a super human signal such as a character signal, a delay circuit that field-delays the shadow key signal, and a shadow delayed by the delay circuit. a feedback loop that applies a key signal to the shadow key signal generator; and a mixing circuit that mixes the output of the shadow key signal generation circuit and the super human signal, and field-feeds the super human signal to generate a shadow key signal. A shadow key signal generator characterized in that: