JPS621318A - Signal changeover device - Google Patents

Abstract

PURPOSE:To obtain an output with arranged frequency characteristic in selective changeover by forming a profile emphasis correction from the 1st signal with an inferior frequency characteristic and superimposing the correction signal onto the 1st signal so as to generate the 3rd signal. CONSTITUTION:A signal whose characteristic is deteriorated is inputted to the 1st input terminal 12. A differentiated waveform (c) is an output of the 2nd order differentiation circuit 14 and introduced to the 3rd input terminal 15. A signal entering the terminal 15 is amplified by an amplifier 20 to form a somewhat sharp 2nd order differentiation pulse (d), which is inputted to an inverting circuit 21. The circuit 21 inverts the polarity of the signal from the amplifier 20 to form a signal (e). The signal (e) is synthesized with the signal from the 1st input circuit 16 at the synthesis circuit 17. A signal (f) having a waveform applied with pre-shoot and overshoot is outputted respectively to the leading and trailing parts of the signal I from the circuit 17. Since the signal (f) has a major component being the output signal of the circuit 16, the level is almost coincident with the level of the signal from the 2nd input circuit 18.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to signal switching@RK that switches and outputs one of a plurality of input signals. Both outputs are tuned so that substantially the same signals are obtained in terms of frequency characteristics and levels.

[Technical background of the invention]

Fig. 3 shows a block diagram of this 1 signal switching device, and 2
This is a schematic representation of the configuration for selecting two signals. In the figure, numerals 1 and 2 are external first and second input terminals corresponding to pins when the device is integrated, and numeral 3 is an output terminal from which a selected signal is derived. are each of the first . A control terminal connected to the second input terminals 4a, 4b and the output terminal 4C, and a signal path #-i from the first input terminal 4a to the output terminal 4C and a signal path #-i from the second input terminal 4b to the output terminal 4c, respectively. A switching signal from 5 is used to set the switching so that one of the signals passes through the signal.

[Problems with background technology]

In the apparatus as shown in FIG. Second input terminal 1.
The signal introduced into 2 is not necessarily a signal with matching frequency characteristics, but may be a signal (I) with degraded high frequency as shown in @4 Figures (I) and (n). .

An undegraded signal (n) may be introduced.

R, G, and B signals from an information processing device can be considered.

If the frequency characteristics of the signals introduced into each input terminal 1 and 2 are different as described above, signals with different frequency characteristics will naturally be output, and when used in the above television receiver, The image quality is poor when displaying broadcast signals, and R
, G, and B signals, the image quality is good. Therefore, it was necessary to adjust the image quality each time the input was selected.

Therefore, in order to eliminate the complexity of image quality adjustment,
It has been proposed to provide a frequency characteristic correction means as shown in FIG.

Figure 5 shows the above frequency characteristics (
(X), which is provided with a correction means 6 (hereinafter referred to as "f special"), and a correction means 6 is provided on the terminal 1 side in order to specifically match the first human knife wound number (1) with the second human knife wound number (f). It is being FIG. 6 shows the correction means 6 installed inside the ICC. However, in the method shown in FIG. 5, preshoot and overshoot are added before the ICK is input, making it difficult to match the level with the second knife mark. In addition, in the case of Fig. 6, since a correction means using emitter peaking is adopted, sufficient improvement of f characteristics cannot be expected, and oscillation may occur as a result.
Problems such as deterioration of crosstalk performance sometimes occurred.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide means that can obtain outputs with uniform f-characteristics even when input signals with different f-characteristics are selected and switched.

[Summary of the invention]

In order to achieve the above object, the present invention provides a means for obtaining a correction signal for edge enhancement from a first signal with poor f-characteristics, and generating a third signal by superimposing this signal and the first signal. A first signal that sets the first and second signals to be substantially equal in level.
and a second input circuit, and a switching circuit that selectively switches between the third signal and the signal from the second input circuit.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the illustrated example.

FIG. 1 is a block diagram showing an embodiment of a signal switching device according to the present invention, and FIG. 2 is an explanatory diagram illustrating an example of f-characteristic correction means according to the present invention.

In FIG. 1, a block 11 indicates an IC main body, and a first signal I and a second signal ■ are introduced into first and second input terminals 12 and 13, respectively, and a first signal A signal from a second-order differentiating circuit 14 that performs second-order differentiation on the signal 2 to generate a third signal is introduced to the third input terminal 15. The signal led to the first input terminal 12 is
The signal is introduced into one input terminal of the synthesis circuit 17 via the first input circuit 16 and led to the second input terminal 13.

The first input 1 of the switching circuit 19 via the second input circuit 18
9a, these first. The amplification degree of the second input circuit 18 is adjusted so that each input signal is output to the next stage circuit at approximately the same level. - 10,000, the signal led to the third input terminal 15 is input to the inverting circuit 21 via the amplifier 20.

The inverting circuit 21 inputs its output to the other input terminal of the circuit 17. The output of this combining circuit 17 is introduced into the second input terminal 19b of the switching circuit 19. In the switching circuit 'pr19, switching conduction is controlled between the first input terminal 19a and the output terminal 19C and between the second input terminal 19b and the output m1Qc by a control signal supply means (not shown).
As a result, the signal appearing at the output terminal 19c is transmitted to the IC main body 11.
It is led out to the output terminal 22 of.

The present invention is configured as described above, and next, the entire operation based on the above configuration will be explained with reference to FIGS. 4 and 2.

Now, suppose that a signal with degraded characteristics as shown in FIG. 4(I) K is input to the first input terminal 1217C, and a signal as shown in FIG. 4(n) K is input to the second input terminal 13. , 1st. The second input circuits 16 and 18F'i output these signals at approximately the same level.

On the other hand, the first signal I is converted into a waveform by the second-order differentiator circuit 14 as shown in FIG. That is, FIG. 2 shows the waveform & conversion operation performed in the second-order differentiating circuit 14, where (a) corresponds to the signal I, and when this signal is first-order differentiated, the rise and the rise of the signal I are shown in (b). A first-order differential waveform showing minute pulses of positive and negative polarity in response to the falling edge is obtained, and when this is further differentiated, a second-order differential waveform as shown in (c) is obtained. This differential waveform (c) becomes the output of the second-order differentiator circuit 14 and is introduced into the third input terminal 15. The signal input to this terminal 15 is amplified by the amplifier 20, becomes a slightly sharp second-order differential pulse as shown in (d), and is input to the inverting circuit 21. The polarity of is reversed to make it look like the signal in Figure 2 (61), and this signal (
e) is combined with the signal from the first human-powered circuit 16 in the combining circuit 17, and the first combining circuit 17 outputs signals to each of the rising and falling parts of the signal I, as shown in FIG. 2(f). Priscini and overshaded
“A drum-shaped signal is output. This signal has a main component that is the output signal of the first input circuit 16.

It is assumed that the level almost matches the level of the signal from the second input circuit 18. Moreover, since the characteristics have been corrected as described above, the f-special signal is equivalent to the second signal, and from the next stage switching circuit 19, the first signal. Regardless of which of the second signals is selected, uniform output signals at approximately f time can be obtained.

In this way, the present invention can eliminate a 1% difference between signals to be selectively switched, and for example, in a nine television receiver having an external input function j=F'i, the picture quality can be adjusted at the time of signal switching. The advantage is that there is no need to do so.

〔Effect of the invention〕

As explained above, according to the present invention, the f special prize signal is
Since there is no need to correct the characteristics before inputting to the IC or correct the characteristics using the emitter peaking method using transistors inside the IC, level matching with other inputs is easy, and unnecessary oscillation and cocoon talk are eliminated. There is an effect that outputs with uniform f characteristics can be selectively outputted without causing any problems.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the signal switching device according to the present invention, FIG. 2 is an explanatory diagram explaining an example of the characteristic correction means according to the present invention, and FIG. 3 is the basics of the signal switching device according to the present invention. FIG. 4 is a block diagram showing the configuration, FIG. 4 is a waveform diagram showing an example of a signal to be selected, FIG. 5 is a block diagram showing an example of a conventional signal switching device, and FIG. 6 is a block diagram showing another conventional device. be. 11... IC body, 12... 1st input terminal, 1
3.--Second input terminal, 14.--Second order differential circuit,
15-Third input terminal, 16.18--Input circuit, 17
- synthesis circuit, 19 - switching circuit, 20 - amplifier, 21 - inverting circuit. Agent: Patent Attorney Kensuke Chika (and 1 other person) 1st
Figure 4 Figure 3 Figure 5

Claims (1)

[Claims] A first input terminal to which the first signal is input, a second input terminal to which the second signal is input, and a signal supplied to the first input terminal and the second input terminal. first and second input circuits that adjust the respective signals to substantially the same level and output them; and a correction signal for obtaining a correction signal for contour enhancement from the first signal supplied to the first input terminal. generating means; signal synthesizing means for superimposing the correction signal on the output signal from the first input circuit and outputting a third signal with enhanced contours; and an output signal from the second input circuit. , the third signal, and a switching means configured to selectively take out and output one of the supplied signals, the first and second input circuits, the signal A signal switching device in which a combining means and a switching means are constructed on the same semiconductor integrated circuit.