JPS6229389A - Hue adjusting device - Google Patents

Abstract

PURPOSE:To attain simple constitution with less unstable element by adding an original color burst signal whose amplitude is adjusted by one-stage of phase shifter, an inverting amplifier and a variable resistor and a color burst signal having a different phase from the original color burst signal by 90 deg. to an adder circuit. CONSTITUTION:The original color burst signal synchronizing with a color burst signal of an original input video signal is fed to an input terminal 10. The original color burst signal becomes a color burst signal e1 having a phase differ ence of 90 deg. at a phase shifter 11, one output of the phase shifter 11 is given to an inverse amplifier 12, from which the color burst signal e1 and a color burst signal e2 having a phase difference of 180 deg. are obtained. The color burst signal e2 has a phase difference of -90 deg. to the original color burst signal, the color burst signals e1, e2 are synthesized by a variable resistor 13, a color burst signal e3 whose amplitude is varied depending on the position of the slider is obtained, the color burst signal e3 and the original color burst signal are fed to an adder circuit 14 to obtain a color burst signal e4. Thus, simple constitu tion with less variation element is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a video signal processing circuit, and particularly to a burst signal phase shifter or hue adjuster.

[Technical Background of the Invention] In general, additional processing is sometimes performed on video signals, and in particular, one example of processing and operations added only to color signals is adjustment of color density and hue. Of these, for hue adjustment, only the color burst signal contained in the original input video signal is extracted, its phase is varied, and the color burst signal of the original input video signal is replaced by δ to form the reference phase for color reproduction. As a result, there are some that change the hue of the human video signal. Below, means for varying the phase of the color burst signal of the video signal will be described with reference to the drawings.

FIG. 3 shows a block diagram for varying the phase of a color burst signal extracted from a video signal. 1 and 2 are phase shifters with the function of varying the phase! and a phase shifter■, and 3
One of the fixed terminals is a volume connected to the output of phase shifter 1, the other is a volume connected to the output of phase shifter 2, and 4 is a limiter that limits the amplitude of the signal voltage.

Next, the operation will be explained. In general, the amount of phase adjustment [yo±
It is determined with 45° as the maximum, and the phase shift amount of phase shifter I is +4
5 degrees, the phase shift amount of phase shifter ■ is -90 degrees, the output of phase shifter I is 05, the output of phase shifter ■ is 06, and the volume 3 that combines e5 and e6 is If the output is 01, the relationship shown in the vector diagram shown in Figure 4 will be obtained, and the output of the variable terminal of volume 3 will be ±45 with respect to the original cover burst signal.
This constitutes a phase shifter for color burst signals that can change the phase within a range of . The output from the variable terminal of the volume 3 becomes a color burst signal with a constant amplitude by a limiter 4 at the subsequent stage.

[Problems in the background art] The above phase shifters I and II are usually constructed using inductances, capacitors, delay lines, etc., and there are manufacturing errors, changes over time, temperature dependence, etc. of the inductance elements, and problems with the capacitor elements. It is difficult to obtain a desired amount of phase shift due to errors in the phase shift, temperature dependence, etc., and characteristics with sufficient accuracy cannot be obtained. Also, regarding delay lines, the management of delay time is difficult, and they have a more detrimental effect than inductance elements and capacitor elements in terms of 11 o'clock changes and temperature dependence. Therefore, since two stages of such phase shifters are required, it is difficult to keep the phase shifter within a predetermined range due to the characteristics. In addition, it is normal to set a midpoint click on the poly-comb 3 and specify a phase shift of 0° that makes the phase of the color burst signal the same as that of the burst signal of the human horn video signal. The change in the phase shifter will directly result in a phase error at the midpoint click, and even if one of the phase shifters is finely adjusted and the phase shift is set to 0° at the midpoint click, changes over time and temperature will occur. This has the disadvantage that errors may occur.

[Object of the Invention] The present invention has been made to eliminate the drawbacks of the conventional ones as described above, and by combining a one-stage phase shifter and an inverting amplifier, the color-verse side of a human-powered video signal is
By creating a color burst signal with a phase difference of 90'' with respect to the signal and adding it to the color burst signal of the Genjin Power Video Shinkyu to an adding circuit, a color burst signal with a variable phase difference of ±45 degrees can be generated. It is an object of the present invention to provide a hue adjuster having a simple configuration with few unstable factors.

[Summary of the Invention] The original colorverse 1-signal synchronized with the color burst signal of the input video signal, and the original colorverse 1-signal synchronized with the original colorverse 1-signal by amplitude adjustment using a one-stage phase shifter, an inverting amplifier, and a polygon. 'A hue adjuster obtained by adding color burst signals having different phases to an adder circuit is provided.

[Embodiment of the Invention] An embodiment of the present invention will be described below based on the drawings. 1st
In the figure, 11 is a phase shifter that obtains an output with a 90° phase difference with respect to the input signal, 12 is an inverter-amplifier that provides a 180° phase difference with respect to the input signal by 1!7, and 13 is the phase shifter. and a volume for combining the respective outputs of the inverting amplifier, 14
1 is an adder circuit, and 15 is a limiter that keeps the amplitude constant.

Next, the operation of the present invention will be explained with reference to the vector diagram shown in FIG. First, the original color burst signal synchronized with the color burst signal of the original human-powered video signal is input to input terminal 1.
Added to 0. The original color burst signal is converted into a color burst signal e1 having a phase difference of 90° by a phase shifter 11.
becomes. One of the outputs of the phase shifter 11 is converted by an inverting amplifier 12 into a color burst signal e2 having a phase difference of 18 degrees from the color burst signal e1. This color burst signal e2 has a phase difference of 190° with respect to the original color burst signal. These color burst signals e1
．． e2 is synthesized by a variable terminal 13, and a variable terminal of the variable terminal 13 receives a color burst signal e3 having a phase difference of 90° with respect to the original color burst signal g and whose amplitude is varied depending on the position of the variable terminal. obtain. The color burst signal e3 and the original color burst signal are added to an adder circuit 14 to obtain a color burst signal e4. Here, assuming that the amplitude of the color burst signal e3 output from the variable terminal of the volume control 13 can be changed to the same amplitude value as the original color burst signal, then the color burst signal e3 output from the adder circuit 14 can be changed to the same amplitude value as the original color burst signal.
4 becomes a color burst signal having a phase difference in the range of ±45'' with respect to the original colorverse 1- signal.

The limiter 15 is used to keep the amplitude constant.

Here, set a middle point click on volume 13 and set the phase difference to 0°.
If you want to be able to indicate the phase difference O at the center point and the link point by adjusting the output amplitude of the inverting an-/12,
If the setting is finely adjusted to °, a stable midpoint click point can be obtained because there is no need to finely adjust constants such as inductance, capacitors, delay lines, etc., which have a large number of changes, and there is no need to finely adjust the phase. That is, in this case, as shown in the vector diagram of FIG. 2, the output at the middle click point of the volume 13 is point A.

In addition, an amplifier is provided after the variable terminal of the volume 13,
By increasing the amplitude of the signal applied to the variable circuit 14, it is possible to obtain a color burst signal that shifts the phase difference in a wider range than the phase difference range of ±45°.

[Effects of the Invention] As described above, according to the present invention, a color burst signal whose amplitude can be varied and has a phase difference of 90° with respect to the original color burst signal can be obtained using a one-stage phase shifter and an inverting amplifier.
Since the configuration is such that a color burst signal with a desired phase difference is obtained by adding the original color burst signal to an adder circuit, the desired hue can be adjusted with a simple configuration that has few variables due to environmental changes such as temperature and humidity, changes over time, etc. You can get the equipment.

Further, with this configuration, even when a midpoint click indicating a phase difference of 0° is provided, it can be easily set by only finely adjusting the amplitude, so that a click point with fewer variable elements can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a hue adjuster according to an embodiment of the present invention, FIG. 2 is a vector diagram of each part to explain the operation of FIG. 1, and FIG. 3 is a block diagram showing a conventional hue adjuster. ,
FIG. 4 shows a vector diagram of each part for explaining the operation of FIG. 3.

Claims (1)

[Scope of Claims] A hue adjuster that varies the phase with respect to a first color burst signal of an original input video signal, comprising: a) phase shifting means for creating a predetermined phase difference with respect to the first color burst signal; and b) variable means for varying the output of the phase shifting means from positive phase to negative phase; c) adding means for adding the second color burst signal of the variable means and the first color burst signal. Hue adjuster with.