KR19980014550A - Television with sub-screen brightness correction - Google Patents

Abstract

The present invention provides a television having a sub-screen brightness correction function so as to improve the overall picture quality by adjusting the sub-screen brightness by adjusting the signal current value of the sub-screen when the main picture is dark when the PIP (Picture In Picture) function of the television is performed Screen mode switching unit 10 for separating the input composite video signal into main / sub composite video signals, and a sub-screen composite video signal input from the multi-screen mode switching unit 10, An amplification unit 40 for amplifying a current image signal of the sub-screen image signal with a predetermined amplification degree, a main screen processing unit 30 for processing a video signal, A main picture processing unit 20 for PIP-processing the composite video signal and the sub-picture image signal applied from the amplification unit 40 to reproduce and output multiple pictures on the CRT 60, A bias unit 50 for outputting an ABL current to the main screen brightness on the basis of a horizontal and vertical synchronization signal and a control unit for controlling the gain of the amplification unit 40 based on the ABL current, And a sub-picture correction circuit for adjusting the sub-picture brightness by adjusting a current value of the sub-picture video signal. In the PIP function, when the main screen of the television is dark, the brightness of the sub- It is possible to provide a high-quality image in multi-screen viewing.

Description

Television with sub-screen brightness correction

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television having a sub-picture brightness correction function, and more particularly, to a television having a sub-picture brightness correction function, in which, when a main picture is dark when a picture in picture (PIP) To a sub-picture correction circuit of a television which can improve the picture quality of an entire television set.

2. Description of the Related Art [0002] In general, a television receiving and reproducing a broadcast signal transmitted from a broadcasting station is gradually becoming a field of application. For example, a plurality of tuners are installed, Tuner function used for searching another channel by tuning another receivable broadcast channel by the other tuner and a broadcast signal for a channel searched by the 2-tuner function to the main screen and the sub- (PIP) function is also added.

1 is a block diagram illustrating a configuration of a conventional television employing such a PIP function. Referring to FIG. 1, a multi-picture mode switching unit 10, a main screen processing unit 20, a sub-screen processing unit 30, (50), and a CRT (60).

Reference numeral 10 denotes a composite video signal reproduced from an external device such as a broadcast signal (hereinafter, referred to as a TV composite video signal) received by the antenna and a video tape recorder when the PIP mode is set, Screen mode switching unit for receiving the composite video signal and dividing the composite video signal into main / sub composite video signals under the control of a microcomputer (not shown). Numeral 20 denotes a main screen composite video signal And a sub-picture image signal output from the amplifying unit 40. The reference numeral 30 designates a main screen processing unit for performing a PIP process on the sub- Signal processing unit for processing a video signal so as to reproduce and output a signal. Reference numeral 40 denotes a current amplifying unit for amplifying a current of a video signal output from the sub-screen processing unit 30, Amplification indicates parts to be applied (20). Reference numeral 50 indicates an ABL current (Automatic Bright Limiting Current) according to the brightness of the main screen based on the horizontal and vertical synchronizing signal outputted from the main screen processing unit 20 to the main screen processing unit 20 And a deflection unit for outputting a deflection signal for driving a deflection coil DY provided in a cathode-ray tube to a deflection coil DY. Reference numeral 60 denotes a deflection unit for deflecting the deflection coil DY, CRT.

According to the conventional television having the sub-screen function, the main screen composite video signal and the sub-screen composite video signal separated by the multi-screen mode switching unit 10 are supplied to the main screen processing unit 20 and the sub-screen processing unit 30 The main screen processing unit 20 receives a main picture composite video signal and outputs a horizontal and vertical synchronization signal to the deflection unit 50. The deflection unit 50 generates a horizontal and vertical synchronization signal based on the horizontal and vertical synchronization signals Applies the ABL current according to the brightness of the main screen to the main screen processing unit 20 and applies the deflection signal to the deflection coil DY. On the other hand, the sub-screen processing unit 30 receiving the sub-screen composite video signal processes the sub-screen composite video signal and applies the video signal to the amplification unit 40. The sub- And is applied to the main screen processing unit 20. [ At this time, the main screen processing unit 20 performs PIP processing on the main screen composite video signal applied from the multi-picture mode switching unit 10 and the sub-screen video signal applied from the amplification unit 40, do. Accordingly, a multi-screen composed of sub-screens is reproduced and output through a predetermined portion of the main screen through the CRT 60.

In the television having the above configuration, when the PIP function is performed, the brightness of the screen output onto the CRT is adjusted according to the ABL current with respect to the brightness of the main screen. Therefore, when the main screen is dark and the sub- The brightness becomes dark due to the brightness of the main screen, and the brightness of the sub-screen becomes relatively prominent. Therefore, the sub picture has a larger size than the reference size, or the boundary between the sub picture and the main picture is unclear.

Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to improve the overall picture quality by adjusting the sub-picture brightness by adjusting the signal current of the sub- And a television equipped with a sub-picture brightness correction function.

In order to achieve the above object, a television equipped with a sub-picture brightness correction function according to the present invention includes: a multi-picture mode switching means for separating an input composite video signal into main / sub composite video signals; Screen image processing means for amplifying a current of the sub-picture image signal processed by the image signal processing by a predetermined amplification degree, a main screen image processing means for performing main screen image processing on the sub- A main screen processing means for PIP-processing the screen composite video signal and the sub-screen video signal applied from the amplifying means to reproduce and output a multi-screen onto the CRT, A bias means for outputting an ABL current to the screen brightness and a gain control means for controlling the gain of the amplification means based on the ABL current, Adjusting the current value in the sub-screen video signal applied to the means for re-correcting circuit is composed of the sub-screen such that the sub-screen brightness are adjusted.

According to a preferred embodiment of the present invention, the base end of the sub-picture correction circuit is connected to the output terminal of the deflection means via a resistance element, and the emitter end is grounded via a resistance element, And a transistor connected to a power supply terminal via a resistance element, and a collector terminal of the transistor is connected to a gain control terminal of the amplifying means via a resistance element.

According to the present invention configured as described above, when the main screen is dark when performing the PIP mode, the sub-screen correction circuit decreases the power supply voltage applied to the amplification means by the ABL current outputted from the deflection means, The amplifying means lowers the signal current value of the sub-picture image signal applied to the main screen processing means. Therefore, as the brightness of the sub-picture PIP-processed by the main screen processing means and output to the CRT is corrected to be dark, it is possible to provide a high-quality picture when the PIP function is performed.

1 is a block diagram of a conventional television employing a sub-picture function,

2 is a diagram showing a configuration of an image processing system of a television equipped with a sub-screen brightness correction function according to an embodiment of the present invention.

Description of the Related Art [0002]

10: Multi-screen mode switching unit, 20: Main screen processing unit,

30: Sub-screen processing unit, 40: Amplification unit,

50: deflection part, 60: CRT,

70: Sub-picture correction circuit.

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

FIG. 2 is a diagram showing a configuration of a video processing system of a television having a sub-screen brightness correction function according to an embodiment of the present invention. Components that perform the same functions as those of FIG. 1 described above are denoted by the same reference numerals And a detailed description thereof will be omitted.

Reference numeral 70 denotes a gain adjusting unit for adjusting the gain of the amplifying unit 40 based on the ABL current with respect to the brightness of the main screen applied from the deflecting unit 50, The sub-screen correction circuit 70 is a sub-screen correction circuit for adjusting the brightness of the sub-screen by adjusting the brightness of the sub- And its emitter terminal is grounded via a resistor R4 and its collector terminal is composed of a transistor T1 connected to a power supply terminal B + via a resistor R2, and the transistor T1 is connected to a gain control terminal of the amplifier 40 via a resistor R3.

Next, the operation of the television having the sub-screen brightness correction function according to the present invention having the above-described configuration will be described in detail.

If the main picture composite signal and the sub picture composite video signal separated by the multi picture mode switching unit 10 are applied to the main picture processing unit 20 and the sub picture processing unit 30, The processing section 20 outputs the horizontal and vertical synchronizing signal to the deflection section 50. In addition, the sub-screen processing unit 30 processes the sub-screen composite video signal and applies the video signal to the amplification unit 40 connected to the subsequent stage.

The deflection unit 50 receiving the horizontal and vertical synchronization signals outputs a deflection signal for driving a deflection coil installed in the cathode ray tube and outputs an ABL current to the main screen brightness by the sub screen correction circuit 70 , The ABL current is inversely proportional to the brightness of the screen, so that the ABL current of a high current value is applied to the sub-screen correction circuit 70 when the main screen is dark. Accordingly, the sub-picture correction circuit 70 turns on the transistor Tl according to the ABL current applied to the base end of the transistor T1 and turns on the collector of the transistor T1 through the resistor R2. The voltage of the collector terminal of the transistor T1 is lowered to the gain control terminal A of the amplifying unit 40 through the resistor R3 as the applied power supply voltage B + The applied gain control voltage is lowered. The amplification unit 40 has a characteristic in which the amplification degree is set in proportion to a voltage applied to the gain adjustment terminal A. When the voltage applied to the gain adjustment terminal A is lower than the reference gain adjustment voltage The amplification degree becomes lower than the existing value. Accordingly, the amplification unit 40 amplifies the current sub-screen image signal applied from the sub-screen processing unit 30 to the main screen processing unit 20 by amplifying the current.

The main screen processing unit 20 performs a PIP process on the sub-screen image signal output from the amplifying unit 40 and reproduces the multi-screen through the CRT 60. At this time, the current value of the sub- The brightness of the sub-screen corresponding to the sub-screen video signal is corrected to be somewhat dark.

On the other hand, when the main screen is bright, since the ABL current value outputted from the main screen processing unit 20 is low, the ABL current inputted to the base terminal of the transistor T1 of the sub- The power supply voltage applied through the resistor R2 to the collector terminal of the transistor T1 is turned off as the reference gain adjustment voltage via the resistor R3 to the gain control terminal A), the amplification unit 40 amplifies the sub-screen image signal applied from the sub-screen processing unit 30 with a predetermined amplification degree and applies the amplified sub-screen image signal to the main screen processing unit 20, The brightness of the sub-screen, which is pushed on the CRT 60, is not corrected.

According to the present invention as described above, when the main picture of the television is dark when the PIP function is performed, the brightness of the sub-picture is automatically corrected, thereby eliminating the screen deterioration requirement between the main and sub- .

Claims (2)

A multi-picture mode switching unit 10 for separating the inputted composite video signal into main / sub composite video signals, A sub-screen processing unit 30 for processing a video signal of the sub-screen composite video signal separated and inputted by the multi-screen mode switching unit 10, An amplifying unit 40 for amplifying the sub-picture image signal processed by the image signal by a predetermined amplification degree, A main picture processing unit 20 for performing a PIP process on the main picture composite picture signal separated from the multi picture mode switching unit 10 and a sub picture image signal applied from the amplifying unit to reproduce and output multiple pictures on the CRT, , A deflection unit 50 for outputting an ABL current for the brightness of the main screen based on the horizontal and vertical synchronization signals applied from the main screen processing unit 20, A sub-screen correction circuit 70 for adjusting a gain of the amplification unit 40 based on the ABL current so as to adjust the sub-screen brightness by adjusting a current value of a sub-screen image signal applied to the main screen processing unit 20, And a sub-screen brightness correction function. The sub-screen correction circuit (70) according to claim 1, wherein the base end of the sub-screen correction circuit (70) is connected to the output terminal of the deflection section (50) via a resistor (R4) The collector terminal of the transistor T1 is connected to the power supply terminal B + via a resistor R2. The collector terminal of the transistor T1 is connected to the power supply terminal B + Is connected to the gain control terminal (A) of the television receiver (40).