KR910007192Y1 - On-screen signal output circuit - Google Patents

Abstract

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Description

On Screen Signal Output Circuit

1 is a circuit diagram of a preferred embodiment according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Character Generator (C.G) 2: CRT Driver

3: MICOM 10: Waveform shaping means

20: inversion amplifier means 30: switching means

C1-C3: Capacitor D1-D4: Diode

R1-R6: resistor Q1, Q2: transistor

The present invention relates to an on-screen signal output circuit, and in particular, to output the on-screen signal according to the selection, and to shape the waveform of the output on-screen signal to prevent bleeding during display, which can display a more on-screen display An on-screen signal output circuit.

VTRs and TVs provide on-screen functions to facilitate user convenience. Conventionally, the microcomputer controls the character generator according to the remote control signal or the key signal, and the character generator transmits the corresponding on-screen signal to the CRT driver. The applied on-screen signal was synthesized with the video signal and displayed on the CRT.

Therefore, whenever a remote control signal or key signal is input, the corresponding character is always on-screen, and the user cannot arbitrarily select the on-screen mode.

In addition, since the on-screen signal output from the character generator is generated by a combination of logic circuits without going through a separate shaping circuit, there is a discontinuity in the display due to the gentle rise time and fall time.

An object of the present invention is to provide an on-screen signal output circuit for outputting the on-screen signal in accordance with the on-screen mode selection in order to solve the problems of the prior art as described above.

Another object of the present invention is to provide an on-screen signal output circuit capable of displaying a clear on-screen display by eliminating bleeding during display by outputting the on-screen signal by waveform shaping.

In order to achieve the above object, the present invention, in outputting the on-screen signal provided from the character generator to the CRT driver, waveform shaping means for waveform shaping the on-screen signal, and amplified waveform on-screen signal And an inverting amplifying means for outputting and a switching means for being turned on at the time of selecting the on-screen mode and supplying a driving power supply voltage to the amplifying means.

When the present invention through the preferred embodiment shown in the accompanying drawings in more detail as follows.

In FIG. 1, the on-screen signal of the character generator 1, which receives data from the microcomputer 3 that receives and decodes a remote control signal or key signal and generates a corresponding character signal, is waveform-formed by the waveform shaping means 10. And inverted and amplified by the inverting amplification means 20 so as to be supplied to the CRT driver 2. The inverting amplification means 20 is an on-screen mode selection signal supplied from the microcomputer 3 The driving power supply voltage VCC is supplied through the switching means 30 turned on.

The waveform shaping means 10 includes a capacitor C1 for bypassing high frequency noise of an on-screen signal to be applied, and a waveform rising time and a reverse characteristic when the waveform is rising, and the reverse characteristic when the waveform is falling. The diode D1 and the resistor R1 shorten the fall time, and the resistor R2 and the capacitor C2 blocking the high frequency components generated when the diode D1 is switched.

The inverting amplification means 20 has a driving power supply voltage VCC through the switching means 30 is supplied to the collector through the resistor R4 and the backflow prevention diode D3, the high range is removed and the waveform is shaped and the resistor R3. The lag time of the on / off characteristic is compensated by connecting the emitter ground transistor Q1, which amplifies the on-screen signal applied to the base and reversely outputs the collector to the collector, and the base emitter of the transistor Q1 in the reverse direction. And a zener diode D4 for clipping a collector output of the transistor Q1 through the resistor R5 to a predetermined level so as to obtain a good inversion waveform.

The switching means 30 is an on-screen mode selection signal applied to the base through the resistor (R6) And a transistor Q2 that outputs the driving power supply voltage VCC supplied to the emitter by being turned on by the low signal of. The capacitor C3 is a capacitor for noise bypass.

The operation and effect of this embodiment configured as described above are as follows.

When the on-screen mode is selected first, the on-screen mode selection signal, which is a low signal through the microcomputer (3), is selected. The driving means voltage VCC is applied to the inverting amplifier circuit 20 by turning on the switching means 30.

In this state, when the data of the microcomputer 3 according to the remote control signal or the key signal is supplied to the character generator 1, a corresponding character signal, that is, an on-screen signal, is applied to the waveform shaping means 10, where the waveform is shaped to rise time. The shaped signal with shortened overfall time is amplified by the inverting amplification means 20 and inverted. The inverted amplification signal is clipped by the zener diode D4 and supplied to the CRT driver 2. Therefore, the on-screen signal with shortened rise time and fall time will reduce bleeding during display.

If the user does not want to display on screen, the on-screen mode selection signal By outputting the high state to turn off the switching means 30 to cut off the supply of the driving power supply voltage (VCC) to the inverted amplification means 20 it is possible to block the on-screen signal output.

As described above, the present invention allows the user to select whether or not to display the on-screen display, and when selecting the on-screen mode, it is possible to prevent bleeding by outputting the waveform-formed on-screen signal, thereby providing clearer on-screen display. It is a useful design to do.

Claims (3)

Outputting an on-screen signal provided from the character generator (1) to the CRT driver (2), comprising: waveform shaping means (10) for shaping the on-screen signal; Inverting amplification means (20) for inverting and outputting the waveform-shaped on-screen signal; Switching means 30 is turned on when the on-screen mode is selected to supply a driving power supply voltage (VCC) to the amplifying means (20); On-screen signal output circuit, characterized in that provided with. 2. The waveform shaping means (10) according to claim 1, wherein the waveform shaping means (10) includes a capacitor (C1) for high frequency noise bypass of an on-screen signal to be applied, a diode (D1) and a resistor for shortening a rise time and a fall time of an on-screen signal waveform. (R1) and a resistor (R2) and a capacitor (C2) for removing high frequency components generated during switching of the diode (D1). The on-screen display of claim 1, wherein the inverting amplification means (20) is supplied to the collector through a reverse current prevention diode (D3) through which the driving power supply voltage (VCC) through the switching means (30) is supplied to the waveform shaped door base. The lag time compensation diode D2 having an on / off characteristic connected in the reverse direction between the emitter ground transistor Q1 for inverting and amplifying the signal and outputting the collector, the base emitter of the transistor Q1, and the resistor R5. And a Zener diode (D4) for clipping the collector output of the transistor (Q1) to a predetermined level.