KR0149581B1 - Circuit for preventing overcasting at image system - Google Patents

Abstract

1. The technical field to which the invention described in the claims belongs:

It relates to an OSD character implementation circuit in television.

2. The technical problem to be solved by the invention:

Conventionally, when the input level of the blanking signal is low when the OSD character is implemented, blurring or slipping occurs.

3. Summary of the solution of the invention:

Since the blanking signal of the OSD text is amplified and maintained at a constant level, the OSD text is prevented from being blurred or pushed out even when the OSD text is displayed on the screen.

4. Important uses of the invention:

A television including a circuit having a microcomputer for implementing OSD characters

Description

On-screen display character blur prevention circuit in video player

1 is a circuit diagram for implementing a conventional OSD.

2 is an OSD character blur prevention circuit diagram according to the present invention.

* Explanation of symbols for main parts of the drawings

28: amplification section 30: mixer section

32: signal transmission unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for implementing On Screen Display (hereinafter referred to as OSD) of an image reproducing apparatus, and more particularly to a circuit for preventing blurring or slipping of OSD characters.

In general, an apparatus for receiving and displaying a text broadcast such as a television requires a separate apparatus for mixing various video signals and an OSD. The device used at this time is called an OSD implementation circuit.

A circuit commonly used to implement a conventional OSD has the configuration as shown in FIG.

Referring to FIG. 1, the operation will be briefly described. The switching unit 10 includes a switching unit 10 when a blanking signal is input from the OSD 12, the external signal input unit 14, and the teletext 16. The control unit controls the corresponding color signal to cut off the output signal of the image reproducing unit 18, and outputs the color signal of the corresponding mode to the screen through a cathode ray tube (CRT).

In this case, when the blanking signal of the OSD is switched through the circuit and inputted to the image reproducing unit 18, when the input level of the blanking signal is low, the OSD characters appearing on the screen may be blurred or a phenomenon may occur.

Accordingly, an object of the present invention for solving the above problems is to provide an on-screen display character blur prevention circuit that amplifies a blanking signal to a set level and stabilizes the on-screen display character.

Another object of the present invention is to provide an on-screen display character blur prevention circuit for mixing a color signal according to an OSD and a color signal generated by an image reproducing unit without using a separate switch.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The OSD character blur prevention circuit according to an embodiment of the present invention has the configuration as shown in FIG. 2, and the configuration according to the embodiment of the present invention is described below with reference to FIG. 2.

The OSD 22 separates a signal (not shown) applied from the outside in relation to the OSD into a color signal and a blanking signal, and divides the OSD text signal composed of the separated color signal and the blanking signal into an image reproducing unit ( 20). The external signal input unit 24 receives an image signal reproduced by an external image reproducing apparatus such as a video and performs an interface function of outputting a color signal + blanking signal to the image reproducing unit 20. The teletext 26 receives a signal according to text multicasting from the outside and outputs a color signal and a blanking signal to the image reproducing unit 20. The image reproducing unit 20 outputs a corresponding color signal to an output terminal when a blanking signal is input from the OSD 22, the external signal input unit 24, and the teletext 26. The amplifier 28 has a blanking signal output current limiting resistor R1 connected between the blanking signal output terminal F / B of the OSD 22 and the base of the transistor Q1, and an emitter of the transistor Q1. And a resistor R2 for limiting the current when a transient current flows between the data emitter and the blanking signal input terminal F / B of the image reproducing unit 20. Therefore, when the OSD blanking signal is input from the OSD 22 to the base of the transistor Q1 by the configuration of the amplifier 28, the blanking of the level set to the emitter by the amplification characteristic of the transistor Q1. Outputs a signal, and the output is applied as a blanking signal F / B of the image reproducing unit 20. The mixer unit 30 includes a color signal output stage including the OSD-R, G, and B signals output from the OSD 22 and a color signal output stage including the final R, G and B signals of the image reproducing unit 20. And diodes D1, D2, and D3 connected to each other to prevent inflow of reverse current from the image reproducing unit 20 to the OSD 22. In addition, during the OSD blanking signal period output from the OSD 22, the OSD color signal and the color signal of the image reproducing unit 20 are mixed and output to the final output terminal. The signal transmitting unit 32 has a resistor R3 connected between the blanking signal output terminal of the external signal input unit 24 and the output terminal of the amplifying unit 28 (a blanking signal input terminal of the image reproducing unit 20). R4 is connected between the blanking signal output terminal of the external signal input unit 24 and ground. In addition, capacitors C1-C3 are connected between the R, G, B signal output terminal of the external signal input unit 24 and the R, G, B input terminal of the image reproducing unit 20, and the resistors R5-R7 are It is connected between the R, G, B output terminal of the external signal input unit 24 and the ground. The diode D4 is connected in a forward direction between the blanking signal output terminal of the teletext 26 and the output terminal of the amplifier 28 (the blanking signal input terminal of the image reproducing unit 20), and the diodes D5-D7 are connected to each other. R, G, and B signal output terminals of the teletext 26 are configured to be forwardly connected between the resistors R5-R7 and the capacitors C1-C3, respectively. The signal transmission unit 32 configured as described above transmits blanking signals and R, G, and B signals input from the external signal input unit 24 and the teletext 26 to the corresponding input unit of the image reproducing unit 20. A blanking signal amplified and output from the amplifying unit 28 to a set level is transmitted to a blanking signal input unit of the image reproducing unit 20. The set level means a signal level such that OSD characters appearing on the screen are not blurred or pushed out. The setting level is determined by measuring the OSD characters displayed on the screen by varying the level value in various forms. Can be. The variable is possible by using transistors Q1 having different amplification characteristics.

Therefore, with reference to the configuration of Figure 2 described above in detail the operation according to an embodiment of the present invention.

When the OSD 22 receives the OSD output recognition, the OSD 22 outputs the OSD blanking signal to the input terminal of the amplifier 28 and outputs the R, G, and B signals of the OSD to the mixer 30. When the blanking signal is induced in the amplifying unit 28, the amplifying unit 28 amplifies the blanking signal to a set level and outputs the blanking signal to the signal transmitting unit 32. The signal transmitting unit 32 transmits the input blanking signal to the image reproducing unit 20, and the image reproducing unit 20 cycles the blanking signal when a blanking signal is input from the signal transmitting unit 32. During the operation, the R, G, and B signals output from the image reproducing unit 20 are blanked and output. The mixer unit 30 mixes the R, G, B signals of the OSD output from the OSD 22 with the R, G, B output signals of the image reproducing unit 20 during the period of the OSD blanking signal. do. At this time, the color signal output from the image reproducing unit 20 in addition to the period is blocked from being introduced into the OSD 22 by the diodes D1, D2, and D3.

As described above, since the present invention amplifies and outputs a blanking signal output from the OSD to a set level, a blanking signal of a stable level is supplied to the image reproducing unit, so that when the OSD text is output on the screen, the OSD text is blurred or pushed. It is effective to provide a better quality screen to the user by preventing from doing. In addition, since it is not necessary to separately provide a switching unit for switching the color signal and the blanking signal output from each configuration, it is possible to simplify the configuration of the circuit has the advantage of economical when producing the product.

Claims (3)

An apparatus for receiving and displaying a text broadcast, comprising: a teletext unit for decoding and playing a text broadcast among received video signals, an external signal input unit for interfacing a video signal applied from an external video playback device, and a signal applied from the outside An on-screen display character generator which is generated by separating the on-screen display character and a blanking signal, an amplifier for amplifying and outputting a blanking signal input from the on-screen display character to a set level, and a blanking applied from the amplification unit. The final output signal by mixing the image reproducing unit which cuts out the output of the image signal during the output period of the signal, and the on-screen display character applied from the on-screen display character generating unit during the period in which the image signal is blocked by the image reproducing unit. A mixer unit for generating a signal from the external signal input unit and the teletext; And a signal transmission unit which provides a blanking signal, an image, and a text signal to the image reproducing unit. 2. The amplifier of claim 1, wherein the amplifier comprises a resistor for amplifying a blanking signal by a predetermined amplification characteristic, a resistor for limiting the blanking signal applied to an input terminal of the transistor, and a transient between an output terminal of the transistor and the image reproducing unit. On-screen display blur prevention circuit, characterized by consisting of a resistor that limits the current when the current flows. The display apparatus of claim 2, wherein the mixer unit comprises a diode which prevents an image signal output from the image reproducing unit from flowing into each output terminal of the on-screen display character provided in the on-screen display character generating unit. On-screen display character blur prevention circuit.