KR19980023251A - Television set with Blooming Prevention - Google Patents

Abstract

According to the present invention, when a white peak signal is mixed in an R, G, and B signal that has been processed for the reason that white narrow characters are continuously output, the CRT beam is output. The present invention relates to a television receiver having a blooming phenomenon which can prevent a blooming phenomenon by reducing current, and an image detector for detecting only an image signal from a broadcast signal received by an antenna and a detected image. A television receiver comprising a video processor for processing a video signal and outputting R, G, and B signals, and a CRT driver for driving and controlling a CRT based on the R, G, and B signals output from the video processor; A white peak detection circuit for detecting the white level of the R, G, and B signals output from the image processing unit more than a predetermined value, and an output terminal voltage of the white peak detection circuit based on a predetermined reference potential level Vref. A detection signal comparator for outputting a determination signal of a first level when the reference potential level is greater than the reference potential level; and a DC level of a predetermined level is superimposed on an input terminal of the white peak detection unit when a high level determination signal is output from the detection signal comparator. It is characterized in that it comprises a DC level supply for supplying to lower the CRT beam (Beam) current.

Description

Television set with Blooming Prevention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver. In particular, a white peak signal is mixed and output in an R, G, B signal that has been processed for image processing such that white narrow characters are continuously output. In this case, the present invention relates to a television receiver having a blooming phenomenon that can prevent a blooming phenomenon by reducing the beam current of the CRT.

The CRT driving stage provided inside the television receiver (hereinafter, referred to as a TV receiver) is configured to perform a function of receiving an image signal processed as an R, G, and B signal and forming an image on the CRT based on the received image signal. 1 is a view for explaining the operation of the CRT driving stage in a conventional TV receiver.

In FIG. 1, reference numeral 1 denotes a remote controller for remotely controlling the operation of the entire apparatus, and 2 denotes a receiver which receives an infrared signal transmitted from the remote controller 1 and converts it into an electrical code signal. It is a microprocessor which executes the control operation for the whole apparatus in accordance with the code signal output from (2).

Further, reference numeral 4 is an antenna for receiving an airwave broadcasting signal, 5 is a tuner for tuning a broadcast signal of a channel selected by the user among the broadcast signals received by the antenna 4, and 6 is a tuner. IF amplification section for amplifying the IF signal output from (5), 7 is a surface for separating the video intermediate frequency signal (PIF) and the audio intermediate frequency signal (SIF) from the IF signal output from the IF amplifier (6), for example P / S separation unit composed of an acoustic wave filter or the like, 8 is a voice detection unit for detecting a voice signal from the SIF signal output from the P / S separation unit 7, and 9 is output from the P / S separation unit 7 An image detector detects an image signal from a PIF signal.

On the other hand, reference numeral 10 denotes a voice such as bass, treble, balance, etc. with respect to the voice signal detected by the voice detector 8 according to a predetermined control signal from the microprocessor 3. 11 is a voice amplifier which amplifies the voice signal processed by the voice processor 10 and outputs it to the speaker 12 connected to the rear stage.

Reference numeral 13 denotes image processing such as color, tint, brightness, or the like for the image signal output from the image detector 9 in accordance with a predetermined control signal from the microprocessor 3. An image processor for outputting R (Red), G (Green), and B (Blue) signals corresponding to an image signal, and 14 denotes a CRT 15 based on an RGB signal outputted from the image processor 13; The CRT driver 14 drives the CRT driver 14 through the resistors R1, R2, and R3 by receiving the R, G, and B signals output from the image processor 13 as inputs of the respective base stages B. Transistors Q1 to Q3 configured to drive the CRT 15 of the collector terminal C connected to the voltage + B1 and resistors R4 provided at the emitter terminal E of each of the transistors Q1 to Q3. , R5, R6, and one end of each resistor (R4, R5, R6) and ground (to adjust the current supplied to the emitter stage E from a 12V drive power (+ B2) It consists of variable resistors R7, R8, and R9 provided between the GNDs.

That is, in the device having the above-described configuration, the microprocessor 3 controls the image processor 13 in response to the user adjusting the video output of the TV screen through the remote controller 1 or the key panel (not shown). By driving control, image output levels such as brightness, contrast, tint, and the like are controlled. As a result, the image processor 13 is controlled by the control of the microprocessor 3. The R (Red), G (Green), and B (Blue) signals are outputted, and the transistors Q1, Q2, and Q3 of the CRT driving unit 14 are driven by the R, G, and B signals. The amount of supply current is adjusted with respect to the CRT 15 connected to the collector terminal C of Q1, Q2, and Q3.

In this case, the levels of the R, G, and B signals applied to the CRT 15 through the collector terminals C of the transistors Q1, Q2, and Q3 are the emitter terminals E of the transistors Q1, Q2, and Q3. The variable resistors R7, R8, and R9 connected to each other are adjusted accordingly.

On the other hand, in the case of TV viewing, for example, when a narrow white character is continuously outputted on the screen in the form of subtitles, the voltage waveforms of the R, G, and B signals output from the image processor 13 are shown in FIG. As illustrated, a white peak appears, and as a result, there is a problem of a blooming phenomenon in which the outline of the character is not clearly seen on the CRT screen.

The present invention has been made in view of the above-described circumstances. For example, a white peak signal is generated in an R, G, B signal that has been processed for image processing, for example, such that a narrow white character is continuously output. In the case of mixed output, the blooming level can be prevented from appearing on the CRT screen by reducing the beam current of the CRT by increasing the DC level of the bias voltage by a predetermined level. Its purpose is to provide a television receiver with protection.

1 is a block diagram showing the internal structure of a conventional general television receiver.

2 is a block diagram showing the internal configuration of a television receiver with a blooming phenomenon prevention function according to an embodiment of the present invention.

3 is a diagram illustrating a state in which white peaks are mixed in an input signal of the CRT driver 14.

4 is a diagram illustrating a state in which a predetermined DC level potential is superimposed on an input signal of the CRT driver 14.

***** Explanation of symbols for the main parts of the drawing *****

1: Remote controller 2: Receiver

3: microprocessor 4: antenna

5: tuner 6: IF amplifier

7: P / S separator 8: voice detector

9: voice processing unit 10: voice amplifier

11 speaker 12 image detector

13 image processing unit 14 CRT driving unit

15: CRT 20: white peak detection circuit

21: detection signal comparator 22: DC level supply

Q1 to Q5: transistors R1 to R15: resistors

In order to achieve the above object, a television receiver having a blooming phenomenon prevention function according to the present invention processes an image detector that detects only an image signal from a broadcast signal received by an antenna, and processes the detected image signal to R, G. And a television receiver having an image processor for outputting a B signal and a CRT driver for driving control of the CRT based on the R, G, and B signals output from the image processor; A white peak detection circuit for detecting the white level of the R, G, and B signals output from the image processing unit more than a predetermined value, and an output terminal voltage of the white peak detection circuit based on a predetermined reference potential level Vref. A detection signal comparator for outputting a determination signal of a first level when the reference potential level is greater than the reference potential level; and a DC level of a predetermined level is superimposed on an input terminal of the white peak detection unit when a high level determination signal is output from the detection signal comparator. It is characterized in that it comprises a DC level supply for supplying to lower the CRT beam (Beam) current.

That is, according to the present invention having the above-described configuration, when white peak signals are mixed and output in the R, G, and B signals that have been processed, the DC level of the bias voltage is increased by a predetermined level. By reducing the beam current of the beam (Blooming) phenomenon can be prevented from appearing on the CRT screen.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention.

FIG. 2 is a block diagram showing an internal configuration of a television receiver having a blooming phenomenon prevention function according to an embodiment of the present invention. Referring to the same elements as those shown in FIG. The numbers will be omitted and the detailed description thereof will be omitted.

In FIG. 2, reference numeral 20 denotes a white peak detection circuit for detecting the white level of the R, G, and B signals output from the image processor 13 when the white level is greater than or equal to a predetermined value. Is the transistor Q4 connected to the emitter terminal E of the transistors Q1, Q2, and Q3 provided in the CRT driving unit 14 through the resistor R15. The coil L is connected between the collector stage C1 and the ground.

Further, reference numeral 21 outputs a high level determination signal when the voltage between both ends of the coil L provided in the white peak detection circuit 20 becomes larger than this reference potential level based on a predetermined reference potential level Vref. When the high level determination signal is outputted from the detection signal comparator 21, the internal transistor Q5 is driven ON, and the white peak detection unit 20 is referred to. It is a DC level supply part which superimposes and supplies a DC level of a predetermined level to the base terminal E1 of the transistor Q4 provided in it.

Next, the operation of the device having the above configuration will be described.

During TV ON driving, a narrow white peak is generated among R, G, and B signals output from the image processor 13, for example, an R (Red) signal as illustrated in FIG. In this case, the potential of the base terminal E of the transistor Q3 provided in the CRT driver 14 is increased, which is applied to the white peak detection circuit 20 through the resistor R15.

As a result, the potential of the emitter terminal E1 of the transistor Q4 provided in the white peak detection circuit 20 becomes high, and accordingly the potential of the collector terminal C1 rises momentarily.

Therefore, the current flowing through the coil L increases, and the voltage between both ends of the coil L becomes larger than the reference voltage Vref of the detection signal comparator 21 so that the high level determination signal is output from the comparator 21. do.

This high level determination signal turns ON the transistor Q5 in the DC level supply section 22, and as a result, the base terminal B1 of the transistor Q4 in the white peak detection circuit 20 is turned on. As the predetermined DC level (+ B2) overlaps, the emitter terminal potential of the transistor Q3 installed inside the CRT driving unit 14 becomes high. As a result, the base terminal of the transistor Q3 is shown in FIG. A signal in which a predetermined DC potential is superimposed is input to reduce the beam current of the CRT, thereby preventing a blooming phenomenon that appears on the screen.

Meanwhile, the present invention is not limited to the above embodiments and can be variously modified within the scope not departing from the technical gist of the present invention.

As described above, according to the present invention, when white peak signals are mixed and output in the R, G, and B signals that have undergone image processing, for example, white narrow characters are continuously output. By reducing the beam current of the CRT, the blooming phenomenon can be prevented.

Claims (1)

An image detector which detects only an image signal from a broadcast signal received by an antenna, an image processor which processes the detected image signal, and outputs R, G, B signals, and an R, G, B output from the image processor A television receiver having a CRT driver for controlling driving of a CRT based on a signal; A white peak detection circuit for detecting a white level of the R, G, and B signals output from the image processing unit when the predetermined level is greater than or equal to a predetermined value; A detection signal comparator for outputting a determination signal of a first level when an output terminal voltage of the white peak detection circuit becomes greater than a reference potential level based on a predetermined reference potential level Vref; And a DC level supply unit configured to reduce a CRT beam current by supplying a DC level of a predetermined level to the input terminal of the white peak detector when the high level determination signal is output from the detection signal comparator. Television receiver with a blooming phenomenon.