JPS6012381Y2 - Image quality adjustment circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an image quality adjustment circuit that provides a simple and inexpensive aperture compensation circuit for use in, for example, television receivers.

First, a conventional image quality adjustment circuit will be explained with reference to FIGS. 1 and 3. 1 is an amplification transistor, 2 is a signal source impedance, 3 is an emitter resistor, 4.5 is a capacitor,
6 is a high frequency transformer, 7 is a damping resistor, 8 is a variable resistor for signal addition, 9 is a signal source, 10.10' is a signal output terminal, and 11 is a DC power supply terminal.

In such a circuit, when a pulse waveform as shown in FIG. 3a is applied as an input signal 9 to the base of the amplifying transistor 1, a parallel circuit of a resistor 3 and a capacitor 4 is connected to the emitter of the transistor 1. However, due to the low output impedance, the output on the emitter side has a waveform approximately equal to that of the base input signal.

This emitter output is applied to the midpoint of the signal addition variable resistor 8.

On the other hand, the collector of the amplifying transistor 1 is first differentiated by the action of the piezoelectric resistor 3 and the capacitor 4, as shown in FIG.

Furthermore, this voltage is differentiated again by the primary coil of the high frequency transformer 6, resulting in a waveform as shown in FIG.

Thereafter, the twice differentiated waveform is induced on the secondary side of the high frequency transformer 6 and applied to one side of the signal summing variable resistor 8.

In this way, the signal from the emitter side and the signal from the collector side are added by the signal addition variable resistor 8.
As shown in FIG. 2, the preshoot and overshoot are adjusted by moving the variable resistor 8 for signal addition.

However, this conventional method requires adjustment of the resonant frequency because it uses a high-frequency transformer, and is also disadvantageous in terms of cost because it also uses the high-frequency transformer and a variable resistor with a center point. There were many points.

The present invention aims not only to eliminate the drawbacks of the above-mentioned conventional method with a simple circuit configuration and to provide an image quality adjustment circuit that can significantly reduce production costs, but also to provide an image quality adjustment circuit that is based on either differential action or integral action. Since the circuit configuration is such that the correction can be adjusted by one variable resistor placed in parallel with the differential inductance, a circuit that can greatly expand the range of adjustment can be obtained.

The present invention will be explained below based on FIGS. 2 and 3.
In FIG. 2, parts corresponding to those in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

First, between the collector of the amplification transistor 1 and the DC power supply terminal 11, there is a differential inductance 12 and an image quality adjustment variable resistor 13 consisting of a normal variable resistor that is not a midpoint type.
A parallel circuit is inserted between the collector and the emitter, and a series circuit of a capacitor 14 and a coupling resistor 15 is connected between the collector and the emitter, and a signal is output from the connection point of the capacitor 14 and the coupling resistor 15 so that the series circuit constitutes a differential circuit. Take out the end 10.10'.

Next, the operation of such a configuration will be explained.A pulse waveform as shown in FIG. A substantially equal waveform is obtained, and the output signal is sent to the signal output terminal 10 via the coupling resistor 15.
．． 10'.

On the other hand, the collector load of the transistor 1, the inductance 12, and the variable resistor 13 for adjusting image quality are driven by a constant current source, and the output on the collector side is the inductance 12.
2, and the collector voltage has a waveform as shown in FIG.

Furthermore, the negative differential voltage is differentiated again by a differentiating circuit consisting of a series circuit of a capacitor 14 and a resistor 15, and then outputted to an output terminal 10.
．． 10', the signal waveform shown in C of the figure is obtained.

In this way, the signal from the emitter side and the signal from the collector side are added at the output terminals 10, 10' to obtain a waveform as shown in the figure d.

In addition, in the above addition, if it is necessary to strictly match the time difference between the two signals, consideration should be given to inserting an inductor for signal delay into the signal derivation circuit from the emitter side, for example, at the time of design.

On the other hand, when the variable resistor 13 for adjusting image quality is set to O [Ω], no signal voltage is generated on the collector side, the -order second-order differential circuit does not operate, and the output waveform on the emitter side is the coupling resistor 15 and capacitor 14. The signal waveform is integrated by the low-pass filter circuit, and a signal waveform as shown in the figure e is obtained at the output terminal 10.10'.

As mentioned above, according to the present invention, a wide range of viewers can enjoy the screen, from hard (contour enhancement) screens based on preshoot and overshoot based on differential action to soft (contour blurring) screens based on integral action. It is possible to easily obtain the image quality according to one's preference, and together with the fact that the above-mentioned wide range of adjustment is possible by using one variable resistor in parallel with the differential inductance, and the capacitor and resistor for both differentiation and integration, The circuit configuration can also be greatly simplified, which provides practical effects.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional example, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is a waveform diagram for explaining FIGS. 1 and 2. In the figure, 1 is an amplification transistor, 2 is a signal source impedance, 3 is an emitter resistance, 9 is a signal source, 10.10' is a signal output terminal, 11 is a DC power supply terminal, 12 is a differential inductance, and 13 is an image quality adjustment 14 is a differential or integral capacitor, 15 is a differential or integral resistor and a coupling resistor.

Claims (1)

[Scope of utility model registration request] In an image quality adjustment circuit consisting of an amplification transistor to which an input signal is applied to the base and whose emitter is grounded via a resistor, a differential inductance and an image quality adjustment inductance are connected between the collector of the amplification transistor and the DC power terminal. In addition to inserting a parallel circuit consisting of a variable resistor, a series circuit consisting of a capacitor and a resistor whose one end is connected to the collector is inserted between the collector and the emitter, and a connecting point between the other end of the capacitor and the resistor is inserted. Image quality adjustment circuit whose output end is derived from.