JPS60105379A - Picture quality adjuster - Google Patents

Abstract

PURPOSE:To make it possible to integrate by composing the picture quality adjuster with the resistance, the fine capacity and the transistor. CONSTITUTION:For the signal inputted from an input terminal 11, the high-pass component is extracted at the 1st filter circuit 14, and the high-pass component is extracted with the different frequency characteristics at the 2nd filter circuit 15. A voltage comparison circuit 18 compares the control signal caused with a control signal occurrence circuit 12 with the standard voltage caused with the reference voltage occurrence circuit 13, and generates a switch signal. An absolute value circuit 20 generates the absolute value of the difference voltage. A switch circuit 19 selectively inputs either of outputs of the 1st and 2nd amplifiers 16, 17 to a gain control circuit 21 with the switch signal, the gain is made variable in accordance with the absolute value voltage and is outputted through a mixing circuit 22 from an output terminal 23.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is a device that handles image signals, such as a magnetic recording/reproducing device or a television device, in which the frequency characteristics of the video signal can be changed using adjustment knobs provided on these devices. This invention relates to a so-called image quality adjustment device that adjusts the clarity of a screen.

Conventional configurations and their problems In recent years, image quality adjustment devices have been made using transistors, coils,
Those configured by combining components such as capacitors and resistors, and those that configure variable gain amplifiers etc. with integrated circuits and are provided with external wave circuits with predetermined frequency characteristics consisting of coils, capacitors, etc. It is used.

An example of such a conventional image quality adjustment device will be described with reference to FIGS. 1 and 2. FIG. 1 is a circuit block diagram of a conventional image quality adjustment device, in which 1 indicates a signal whose frequency characteristics should be changed, such as a video signal reproduced and demodulated in a magnetic recording/reproducing device (hereinafter referred to as rVTRJ), or a television received image. 2 is a control signal generation circuit that generates a control signal in conjunction with the picture quality adjustment knob provided on the VTR or TV; 3 is a predetermined a reference voltage generation circuit that generates a reference voltage; 4 a differential circuit that generates a difference voltage between the control signal generated by the serial control signal generation circuit 2 and the reference voltage generated by the reference voltage generation circuit 3;
5 is a first wave circuit having a predetermined frequency characteristic, for example, a characteristic that emphasizes high frequencies; 6 is a second wave circuit that has a frequency characteristic different from that of the first wave circuit 5, for example, a characteristic that attenuates high frequencies; 7 and 8 are first and second gain control circuits whose gains vary according to the control signal, and 9 is a mixing circuit that mixes the outputs of the first and second gain control circuits to obtain a sum signal. , 10 are output terminals for signals whose frequency characteristics are changed in accordance with the control signal.

The high frequency of the signal input from the input terminal 1 is emphasized by the first wave circuit 5, amplified or attenuated by the first gain control circuit 7, and the high frequency is amplified by the second wave circuit 6. The signal is attenuated and then amplified or attenuated by the second gain control circuit 8. Here, the gains of the first and second gain control circuits 7.8 are set to G+
, G2, and G1+G2 =Qo. On the other hand, the difference voltage between the control signal generated by the control signal generation circuit 2 and the reference voltage generated by the reference voltage generation circuit 3 is obtained by the difference circuit 4. The gains G+ and G2 of the first and second gain control circuits 7.8 vary depending on the differential voltage obtained by the differential circuit 4, and the gains G+ and G2 of the first and second gain control circuits 7. When the second gain control circuit 7.8 is configured, the sum signal of the first and second gain control circuits 7.8 is mixed in the mixing circuit 9 and outputted from the output terminal 10, and the low frequency component is controlled. GO is always constant regardless of the signal; the low frequency component is most emphasized when G1=Qo, G2-0, and the high frequency component is most attenuated when G2=Qo, G1-0. Further, at G1U02, high frequency components are neither emphasized nor attenuated, and are output almost flat with respect to low frequency components.

FIG. 2 shows the frequency characteristics of each part of the conventional image quality adjustment device shown in FIG. It is larger than 1. b is the frequency characteristic of the second wave circuit 6, in which the low frequency level is 1 and the high frequency level is less than 1. The first wave circuit output signal having the frequency characteristic a is amplified or attenuated by the first gain control circuit 7 with a gain G1, and the second wave circuit output signal having the frequency characteristic b is amplified or attenuated by the first gain control circuit 7. The gain control circuit 8 amplifies or attenuates with a gain G2. C is the frequency characteristic of the output signal of the mixing circuit 9, and the low frequency level is the sum of G1 and 02, that is, G
o = constant, and the high frequency level is G1. It can take any value between a and b depending on the value of G2.

However, in the conventional configuration as described above, the sum of the frequency characteristics of the first and second wave circuits 5.6 must be approximately flat, so there are limitations to the characteristics, and parts such as coils are However, there were problems such as the inability to integrate all the circuits.

OBJECT OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional technology, and is constructed using a resistor, a small capacitance, and a transistor, and the entire circuit except for a part of the control signal generator including the knobs provided on a VTR or TV. It can be integrated, and when the knob is at the specified position, the input signal is output exactly as it is, when the knob is changed from the specified position to one side, the high frequency characteristics are emphasized, and when it is changed to the other side, the high frequency characteristics are emphasized. The object of the present invention is to provide an image quality adjustment device in which high frequency characteristics are attenuated.

Structure of the Invention In order to achieve the above object, the image quality adjustment device of the present invention includes: input means for a signal whose frequency characteristics are to be changed; control signal generation means for generating a control signal; and reference voltage input means for generating a predetermined reference voltage. generating means; voltage comparison means for generating a switch switching signal by comparing the control signal generated by the control signal generating means with the reference voltage obtained by the reference voltage generating means; an absolute value voltage generating means for generating an absolute value voltage of a differential voltage; a first wave means having a predetermined frequency characteristic; and a second wave means having a frequency characteristic different from that of the first wave means. gain control means whose gain is controlled by the absolute value signal generated by the absolute value voltage generating means; a switch means for selectively supplying the signal to the gain control means via either the first wave means or the second wave means; and mixing means for adding or subtracting from the output signal, and is configured to obtain, from the mixing means, an output signal whose frequency characteristics have been changed in accordance with the control signal.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a circuit block diagram of an image quality adjustment device according to an embodiment of the present invention. In FIG. 3, 11 is an input terminal for a signal whose frequency characteristics are to be changed, 12 is a control signal generation circuit that generates a control signal in conjunction with the image quality adjustment knob, and 13
14 is a first wave circuit having a predetermined frequency characteristic, for example, a first high-pass characteristic; 15 is a frequency different from that of the first wave circuit 14; 16. 17 is an amplifier circuit for amplifying the first and second wave circuit outputs; 18 is the control signal generating circuit 12;
A voltage comparison circuit 19 compares the control signal generated by the reference voltage generation circuit 11 with the voltage 11 generated by the reference voltage generation circuit 13 and generates a switch switching signal. A switch circuit that selects and outputs one of the circuit output signals q; 20 an absolute value circuit that obtains the absolute value voltage of the difference voltage between the control signal and the reference voltage; 21 an absolute value circuit that obtains the absolute value voltage of the difference voltage between the control signal and the reference voltage; A gain 19 control circuit whose gain changes depending on a value signal; 22 is a control circuit that connects the signal input through the input terminal 11 and the gain series control circuit 2;
A mixing circuit 23 is an output terminal for a signal whose frequency characteristics have been changed in accordance with the control signal.

The signal input from the input terminal 1 is sent to the first filter circuit 14.
The high frequency component is extracted and amplified by the first amplifier 16,
In addition, the second ripple circuit 15 extracts high-frequency components with different frequency characteristics from those of the first ripple circuit 14, and the second ripple circuit 15 extracts the high frequency components.
is amplified. On the other hand, the voltage comparison circuit 18 compares the control signal generated by the control signal generation circuit 12 and the reference voltage generated by the reference voltage generation circuit 13 to generate a switch changeover signal. Further, the absolute value circuit 20 generates an absolute value voltage of the difference voltage between the control signal and the reference voltage. The switch circuit 19 selectively inputs either the first or second amplifier output to the gain control circuit 21 according to the output of the voltage comparison circuit 18, and the gain control circuit 21 controls the gain according to the output of the absolute value circuit 20. is input to the mixing circuit 22 at a level corresponding to the output signal of the absolute value circuit 20, mixed with the input signal by the mixing circuit 22, and outputted from the output terminal 23. Here, the gain of the gain control circuit 21 is zero or small when the absolute value circuit output is small, and becomes large when the absolute value circuit output becomes large.

FIG. 4 shows an example of the frequency characteristics of each part of the image quality adjustment device shown in FIG. 3, and a represents the frequency characteristics when the first wave circuit 14 is divided into two circuits. b is the frequency characteristic when the second wave circuit 15 is made up of several circuits. Here, when the mixing circuit 22 is an adder circuit, the amplifier 16 has a negative gain -A1, and the amplifier 17 has a negative gain -A1.
Assuming that A2 is right, A1 is greater than 1, and A2 is 1, the gain of the gain control circuit 21 changes between O and 1,
When the control voltage is equal to Utp=voltage, that is, when the output of the absolute value circuit 20 is zero, the gain is zero, and when the control voltage becomes larger or smaller than the U quasi-voltage, the output of the absolute value circuit 20 becomes larger and the gain becomes larger and approaches 1. On the other hand, when the control voltage is larger than the reference voltage, the output of the first wave circuit 14 is inputted to the gain control circuit 21 with a gain of 1 A1, and the gain of the gain control circuit 21 is set to K.
In this case, the output of the mixing circuit 22 has a characteristic in which a predetermined frequency is emphasized in the two-several characteristic shown in C, which varies depending on the product of the gain 41At and K. Further, when the control voltage is smaller than the reference voltage, the second filter circuit 15 is inputted to the gain control circuit 21 with a gain of 1, and the gain of the second filter circuit 15 is 1.
Assuming that the gain of is K, the output of the mixing circuit 22 has a characteristic (q) in which the high frequency is attenuated and has a characteristic of several machines shown in C that varies according to the gain K.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, as described in detail, the frequency characteristics are changed.
a control signal generating means for generating a control signal, a reference voltage generating means for generating a predetermined reference voltage, and a control signal generated by the control signal generating means and the reference voltage generating means; voltage comparison means for generating a switch switching signal by comparing the voltage with a reference voltage obtained by the means; 1
1. Absolute value voltage generating means for generating an absolute value voltage of the voltage difference between the voltage difference between 1 Onin 8 and the reference voltage;
a second wave means having a frequency characteristic different from that of the first wave means; and a gain control means whose gain is controlled by the absolute value signal generated by the absolute value voltage generating means. , the signal inputted by the manual means is controlled by the switch switching signal generated by the voltage comparing means, and is transmitted to the gain control means through either the first wave means or the second wave means. and a mixing means for adding or subtracting the signal inputted by the input means and the output signal of the gain control means, from the mixing means to the υj control signal. Since the output signal whose frequency characteristics have been changed according to By creating a circuit for two or more machines, etc., which can be constructed by combining one or more circuits of one machine with an emitter-hole circuit, it can be realized without using a coil, and the capacitance value can be reduced to several EIF.
10-odd pF is sufficient, making it possible to integrate this on an integrated circuit. All the circuits except the II ill voltage generation means can be integrated. Furthermore, when the control signal and the reference signal are approximately equal, by setting the gain 19 of the gain control means to zero, the input signal is output as an output signal without being affected by the first and second wave means. The frequency characteristics of the first and second wave means can be set independently, unlike the conventional example.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of a conventional image quality adjustment device, FIG. 2 is an explanatory diagram of frequency characteristics of the same image quality adjustment device, FIG. 3 is a circuit block diagram of an image quality adjustment device according to an embodiment of the present invention, and FIG. The figure is an explanatory diagram of the frequency characteristics of the image quality adjustment device. 111--input terminal, 12--control signal generation circuit,
13... Reference voltage generation circuit, 14.15... Filter circuit, 16.17... Amplifier circuit, 18... Voltage comparison circuit, 19... Switch circuit, 20... Absolute value circuit ,
21... Gain control circuit, 22... Mixing circuit, 23.
...Output terminal agent Yoshihiro MorikiFigure 1Figure 2Figure 3Figure 4

Claims (1)

[Claims] 1. An input means for a signal whose frequency characteristics are to be changed, a control signal generation means for generating a control signal, a reference voltage generation means for generating a predetermined reference voltage, and the control signal generation means. voltage comparing means for generating a switch switching signal by comparing the obtained control signal with the reference voltage obtained by the reference voltage generating means; an absolute value voltage generating means for generating an absolute value voltage of a difference voltage, a first wave means having a predetermined frequency characteristic, and a second wave means having a frequency characteristic different from the first wave means. a wave means whose gain is controlled by the absolute value signal generated by the absolute value voltage generating means, and a gain control means whose gain is controlled by the absolute value signal generated by the voltage comparing means and which is input by the input means. a switch means for selectively supplying a signal to the gain control means via either the first wave means or the second wave means; a switch means for selectively supplying a signal to the gain control means; 1. An image quality adjustment device comprising: mixing means for adding or subtracting an output signal from a control means, and obtaining from said mixing means an output signal whose frequency characteristics have been changed in accordance with said control signal. 2. The frequency characteristics of the first wave means are those of several units, and the frequency characteristics of the second
The frequency characteristics of the wave means have two characteristics, and the mixing means has the frequency characteristics of the signal inputted by the input means and )11
The image quality adjusting device according to claim 1, wherein the image quality adjusting device is configured to subtract and mix the output signal of the first or second wave means whose gain is controlled by the gain control means.