JP3412326B2 - Blooming suppression circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blooming suppression circuit for a color television receiver.

[0002]

2. Description of the Related Art In recent years, with the increase in brightness of television receivers, there is a blooming suppressing circuit for suppressing blooming that occurs in a scene where ABL is less likely to occur in a transient state when power is turned on, that is, blooming suppressing circuit. It is emphasized.

A conventional blooming suppressing circuit will be described below with reference to FIG. FIG. 10 shows a configuration of a conventional blooming suppressing circuit. In FIG. 10, 1
A contrast circuit 00 inputs the contrast adjustment value a and the luminance signal b of the video signal, adjusts the gain of the input luminance signal b according to the contrast adjustment value a, and outputs the contrast adjusted luminance signal output c. is there. 10
1 is the input of the luminance signal output c of the contrast circuit 100 and the peak limit setting value e, and the input luminance signal output c
If the peak limit level e exceeds the peak limit level e, the peak limit level e is output as a luminance signal.
This is a limit circuit that directly outputs the input luminance signal.

The operation of the blooming suppressing circuit configured as described above will be described below with reference to FIG.

First, as shown in FIG. 10, the brightness signal b of the video signal is input to the contrast circuit 100, and the gain of the input brightness signal b is adjusted by the contrast adjustment value a, and the brightness of the contrast adjusted. The signal output c is output. Then, the brightness signal output c of the contrast circuit 100 is input to the limit circuit 101, and when the input brightness signal output c exceeds the separately input peak limit level e, the peak limit level e is output as a brightness signal and exceeds the peak limit level e. If not, the input luminance signal is output as it is. The peak limit level e at this time is set to a level at which blooming does not occur even in a scene in which ABL is unlikely to occur in a transient state such as when the power is turned on.

[0006]

However, in the above configuration, if the peak limit level is set so that blooming does not occur even in a scene where ABL is less likely to occur in a transient state such as when the power is turned on, the peak limit level is set. Since the level was set to be rather low, the white side of the video signal was likely to occur in the image, which was a cause of image quality deterioration.

The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a blooming suppressing circuit in which a limit circuit does not generate a white side hit of a video signal.

[0008]

In order to solve the above-mentioned problems, a blooming suppressing circuit of the present invention inputs a contrast adjustment value and a luminance signal of a video signal, and according to the contrast adjustment value, the input luminance signal Input the contrast circuit that outputs the brightness signal output with the contrast adjusted by gain adjustment, the delay time setting value, the power-on signal and the contrast setting value, and detect when the power-on signal turns from the off state to the on state and turn it on. At that time, the contrast adjustment value is once set to a value smaller than the contrast setting value, and then the contrast adjustment value is gradually increased to the contrast setting value until the time set by the delay time is reached. It consists of a processor.

Further, a red beam current detection transistor (hereinafter referred to as Tr), in which a red cathode side of a cathode ray tube (hereinafter referred to as CRT) is connected to an emitter and a red video signal is input to a base, Connect the green cathode side of the CRT to the emitter and connect the green video signal to the base to input the green beam current detection Tr, and connect the CRT blue cathode side to the emitter and input the blue video signal to the base. Tr for blue beam current detection and Tr for red beam current detection
And Tr for green beam current detection and T for blue beam current detection
Connect the collector of r, connect the connection end to one,
The other is grounded, and the beam current detection resistance that combines the red, green, and blue beam currents and converts them into a voltage, and the AD that converts the beam current waveform converted into a voltage into a digital signal by the beam current detection resistance Input a converter, a maximum value detection circuit for detecting the maximum value of the digital signal from the AD converter for each field in the video signal area and outputting it as a maximum beam current value, a contrast adjustment value and a brightness signal of the video signal. The contrast circuit adjusts the gain of the input luminance signal according to the contrast adjustment value and outputs the contrast-adjusted luminance signal output, the contrast setting value, the beam current detection start time setting value, the delay time setting value, and the power supply. Input the ON signal, maximum beam current value and beam current threshold value, and detect when the power ON signal changes from OFF state to ON state and turn ON. Load the maximum beam current value at the time set by the beam current detection starting time setting value from,
If the value is larger than the beam current threshold, set the contrast adjustment value to a value smaller than the contrast setting value and then gradually adjust the contrast to the contrast setting value until the time set by the delay time setting value is reached. When the maximum beam current value is smaller than the beam current threshold value, the processor is configured to set the contrast adjustment value without correcting the contrast adjustment value.

Further, the red cathode side of the CRT is connected to the emitter, and the red beam current detection Tr for inputting the red image signal to the base and the green cathode side of the CRT are connected to the emitter to obtain the green image. A green beam current detecting Tr for inputting a signal to the base, a blue cathode side Tr for connecting a blue cathode side of a CRT to an emitter and inputting a blue video signal to the base, and a red beam current detecting Tr. Beam current detection Tr
And Tr for green beam current detection and T for blue beam current detection
Connect the collector of r, connect the connection end to one,
The other is grounded, and the beam current detection resistance that combines the red, green, and blue beam currents and converts them into a voltage, and the AD that converts the beam current waveform converted into a voltage into a digital signal by the beam current detection resistance A maximum beam current detection circuit composed of a converter and a maximum value detection circuit that detects the maximum value of the digital signal from the AD converter in the video signal area and outputs it as the maximum beam current value, a contrast adjustment value and a video signal , A contrast circuit that outputs the contrast-adjusted luminance signal output by adjusting the gain of the input luminance signal according to the contrast adjustment value, and the contrast setting value, minimum contrast adjustment value, and beam current detection. Enter the start time setting value, delay time setting value, power-on signal, maximum beam current value and beam current threshold value, and the power-on signal When it is turned on from the full state, the contrast setting value is set to the contrast adjustment value, the contrast setting value and the minimum contrast adjustment value are compared, and if the minimum contrast adjustment value is large, no contrast correction is performed, If the minimum contrast adjustment value is small, read the maximum beam current value at the time set by the beam current detection start time setting value.If the value is larger than the beam current threshold value, set the contrast adjustment value to the minimum contrast adjustment value. If the maximum beam current value is smaller than the beam current threshold value, the contrast is adjusted so that the contrast adjustment value is gradually increased to the contrast setting value by the time set by the delay time setting value. , Do not correct the contrast adjustment value and directly set the contrast setting value And it constitutes from the processor without the jar.

[0011]

With the above-described structure, the present invention gradually changes from the state in which the contrast is lower than the normal value in the transitional state from when the power-on signal is turned on to when the television receiver becomes stable. In addition, it is possible to prevent the occurrence of the white side hit of the video signal by the limit circuit by increasing the data to the normal time.

[0012]

【Example】

(Embodiment 1) Hereinafter, a blooming suppressing circuit of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a blooming suppressing circuit according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 inputs a contrast adjustment value a and a luminance signal b of a video signal, adjusts the gain of the input luminance signal b according to the contrast adjustment value a, and outputs a contrast-adjusted luminance signal output c. It is a contrast circuit.
A delay time setting value d, a power-on signal e, and a contrast setting value f are input, and when the power-on signal e is changed from an off state to an on state, the contrast adjustment value a is contrasted at the time when it is turned on. This is a processor that is set to a value smaller than the set value f, for example, 50%, and then gradually increases the contrast adjustment value a to the contrast set value f until the time set by the delay time set value d is reached. .

The operation of the blooming suppressing circuit configured as described above will be described below with reference to FIGS. 1 and 2.

In FIG. 1, first, when the power of the television receiver is off and the power-on signal e is in the off state, the power is turned on and the power-on signal e is turned on. 11 detects. Processor 1
When 1 detects that the power-on signal e is turned on, the contrast setting value f is set to 5 for the contrast circuit 10.
A value of 0% is output as the contrast adjustment value a. Then, as shown in FIG. 2, after the power is turned on, the contrast adjustment value a is gradually increased until the contrast set value f of 100% is reached until the time set by the delay time is reached.

Therefore, the amplitude of the brightness signal output c output from the contrast circuit 10 can be suppressed to a low level in the transitional state from the power-off state to the on-state until the television receiver operates stably. Blooming does not occur even when a large-amplitude luminance signal b is input.

(Second Embodiment) FIG. 3 shows the configuration of a blooming suppressing circuit according to a second embodiment of the present invention. In FIG. 3, reference numeral 20 denotes a red beam current detection Tr which connects the red cathode side of the CRT to the emitter and inputs the red image signal to the base. Reference numeral 21 denotes a green beam current detection Tr which connects the green cathode side of the CRT to the emitter and inputs the green video signal to the base.

Reference numeral 22 is a blue beam current detection Tr which connects the blue cathode side of the CRT to the emitter and inputs the blue video signal to the base. Reference numeral 23 connects the collectors of the red beam current detection Tr20, the green beam current detection Tr21 and the blue beam current detection Tr22, connects the connection ends to one, and grounds the other to connect red and green. A beam current detection resistor that combines the blue beam current and converts it into a voltage. Reference numeral 24 is an AD converter that converts the beam current waveform converted into a voltage into a digital signal by the beam current detection resistor.

Reference numeral 25 is a maximum value detection circuit for detecting the maximum value of the digital signal from the AD converter in the video signal area and outputting it as the maximum beam current value. A contrast circuit 26 receives the contrast adjustment value a and the brightness signal b of the video signal, adjusts the gain of the input brightness signal according to the contrast adjustment value a, and outputs the brightness signal output c subjected to the contrast adjustment. .

Reference numeral 27 is input with a contrast setting value f, a beam current detection start time setting value g, a delay time setting value e, a power-on signal e, a maximum beam current value h and a beam current threshold i, and the power-on signal e is turned off. Beam current detection start time set value g
Read the maximum beam current value h at the time set by
If the value is larger than the beam current threshold i, the contrast adjustment value a is once set to a value smaller than the contrast setting value f, and then the contrast setting value is gradually increased until the time set by the delay time setting value d is reached. If the maximum beam current value h is smaller than the beam current threshold i, the contrast adjustment value a is increased to f,
This is a processor that does not perform correction on the contrast adjustment value a.

The operation of the blooming suppressing circuit according to the second embodiment having the above configuration will be described below with reference to FIGS. 3, 4 and 5.

In FIG. 3, first, when the power of the television receiver is off and the power-on signal e is in the off state, the power is turned on and the power-on signal e is turned on. 27 detects. Processor 2
When 7 detects that the power-on signal e is turned on,
From turning on to the time set by the beam current detection start time set value g, the time set by the beam current detection start time set value g by setting the contrast adjustment value a to the contrast set value f as an initial value When the maximum beam current value h output from the maximum beam current detection circuit 25 is read and the value is larger than the beam current threshold i, that is, when a large peak current is detected,
As shown in FIG. 4A, the contrast adjustment value a is once set to a value smaller than the contrast setting value f, for example, 50% of the contrast setting value, and then set to the time set by the delay time setting value d. Until then, the contrast adjustment value a is gradually increased to the contrast setting value f, and the amplitude of the luminance signal output c is suppressed.

Further, as shown in FIG. 5, when the maximum beam current value h is smaller than the beam current threshold i, that is, when there is no large peak beam current, the contrast setting value a is not corrected and the contrast setting value f is not corrected. To set.

Therefore, in the transitional state from the power-off state to the on-state until the television receiver operates in a stable state, the amplitude of the luminance signal output c output from the contrast circuit 20 is an excessive beam beam current. Is suppressed so that blooming does not occur even if a large-amplitude luminance signal b is input. Further, since the correction is performed only for the signal in which the excessive peak current flows, in the case of a dark signal, the contrast does not decrease and the image does not become too dark.

(Third Embodiment) A blooming suppressing circuit according to a third embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 shows the configuration of a blooming suppressing circuit according to the third embodiment of the present invention. In FIG. 6, reference numeral 30 denotes the emitter connected to the red cathode side of the CRT,
This is a red beam current detection Tr which receives a red image signal as a base. Reference numeral 31 is a Tr for green beam current detection in which the green cathode side of the CRT is connected to the emitter and the green video signal is input to the base. Reference numeral 32 is a blue beam current detection Tr which connects the blue cathode side of the CRT to the emitter and inputs the blue video signal to the base. 33 is a red beam current detection Tr30 and a green beam current detection Tr
31 and the collector of the blue beam current detection Tr32 are connected, the connection end is connected to one side, the other is grounded, and the beam current detection for combining the red, green and blue beam currents and converting them into a voltage It is resistance.

Reference numeral 34 is an A for converting a beam current waveform converted into a voltage by a beam current detection resistor into a digital signal.
It is a D converter. Reference numeral 35 is a maximum value detection circuit that detects the maximum value of the digital signal from the AD converter 34 within the video signal area and outputs it as the maximum beam current value. Reference numeral 36 denotes a contrast adjustment value a and a luminance signal b of a video signal, and the contrast adjustment value a adjusts the gain of the inputted luminance signal b to obtain a contrast-adjusted luminance signal output c.
Is a contrast circuit for outputting.

37, the contrast setting value f, the minimum contrast adjustment value j, the beam current detection start time setting value g, the delay time setting value d, the power-on signal e, the maximum beam current value h, and the beam current threshold value i are input. The maximum beam current value h at the time set by the beam current detection start time setting value g after the power-on signal e is detected to be turned on from the off state and turned on is read.

When the value is larger than the beam current threshold i, the contrast setting value f is compared with the minimum contrast adjustment value j, and when the contrast setting value f is large, the contrast adjustment value a is set to the minimum contrast adjustment value j. After setting, the contrast adjustment value is gradually increased from that setting value to the time set by the delay time setting value d so as to be equal to 100% of the contrast setting value f. Directly sets the contrast setting value f to the contrast adjustment value a.

Even when the maximum beam current value h is smaller than the beam current threshold value i, the contrast setting value f is directly set without correcting the contrast adjustment value a.

The blooming suppressing circuit according to the third embodiment having the above configuration will be described below with reference to FIGS.
The operation will be described with reference to FIGS. 8 and 9. First, FIG.
As shown by, the processor 37 turns on the power-on signal e from the state where the power of the television receiver is off and the power-on signal e is off. To detect. The processor 37 compares whether the contrast setting value f is smaller than the minimum contrast adjustment value j, and if it is smaller, sets the contrast adjustment value a to the contrast adjustment value a as shown in FIG. 7 to suppress blooming. No correction is made. If it is larger, the contrast adjustment value f is set as the initial value of the contrast adjustment value a.

The contrast adjustment value f is maintained at the beam current detection start time set value g until the time set by the beam current detection start time set value g after the power is turned on.
The maximum beam current value h output from the maximum beam current detection circuit 35 at the time set by is read, and when the value is larger than the beam current threshold i, that is, a large amplitude signal is input and a large peak current flows. If it is, the contrast adjustment value a is set to the minimum contrast setting value j as shown in FIG. 9, and then 100% is gradually set until the time set by the delay time setting value d is reached.
The contrast adjustment value a is increased to the contrast setting value f of, and the amplitude of the luminance signal output c is suppressed.

As shown in FIG. 8, when the maximum beam current value h is smaller than the beam current threshold value i, that is, when a signal with a small amplitude is input and there is no large peak beam current, the contrast adjustment value a is changed. The contrast setting value f is set as it is without performing correction.

Therefore, in the transitional state from the power-off state to the on-state until the television receiver operates stably, the amplitude of the luminance signal output c output from the contrast circuit 30 is an excessive beam beam current. Is suppressed so that blooming does not occur even if a large-amplitude luminance signal b is input.

Further, since the correction is made only for the signal in which the excessive peak current flows, in the case of a dark signal, the contrast does not decrease and the image does not become too dark. Since the lower limit of the contrast adjustment value a is determined by the minimum contrast setting value j, it is possible to prevent the image from becoming too dark due to contrast correction.

According to the present invention, by the above control method, the contrast is lowered from the value at the normal time in the transient state from when the power-on signal is turned on to when the television receiver becomes stable. By gradually increasing the data to the normal data, it is possible to prevent the white area of the video signal from being generated by the limit circuit.

[0037]

As described above, according to the present invention, the contrast is lowered from the normal value in the transient state from when the power-on signal is turned on to when the television receiver becomes stable. By gradually increasing the data from the state to the normal data, it is possible to prevent the white area of the video signal from being generated by the limit circuit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a blooming suppressing circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a time change of contrast correction control according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a blooming suppressing circuit according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a time change of contrast correction control when a luminance signal that allows a large peak beam current to flow is input according to the second embodiment of the present invention.

FIG. 5 is a diagram showing a change over time in control of contrast correction in the case where a luminance signal that prevents a large peak beam current from flowing in the second embodiment of the present invention is input.

FIG. 6 is a block diagram showing a blooming suppressing circuit according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a change over time in control of contrast correction when the contrast setting value according to the third embodiment of the present invention is smaller than the minimum contrast adjustment value.

FIG. 8 shows a time change of contrast correction control when the contrast setting value of the third embodiment of the present invention is larger than the minimum contrast adjustment value and a luminance signal that prevents a large peak beam current from being input. Figure

FIG. 9 is a diagram showing a time change of contrast correction control when the contrast setting value of the third embodiment of the present invention is larger than the minimum contrast adjustment value and a luminance signal that allows a large peak beam current to be input.

FIG. 10 is a block diagram showing a conventional blooming suppressing circuit.

[Explanation of symbols]

10, 26, 36, 100 Contrast circuit 11, 27, 37 processors 20, 30 Tr for red beam current detection 21, 31 Tr for green beam current detection 22, 32 Tr for blue beam current detection 24, 34 Beam current detection resistor 25,35 AD converter 101 limit circuit

Claims (2)

(57) [Claims] 1. A red video current detection Tr, in which an emitter is connected to a red cathode side of a CRT, and a red image signal is input to a base, and an emitter is connected to a green cathode side of the CRT to connect a green image. A green beam current detecting Tr for inputting a signal to the base, a blue beam current detecting Tr for connecting a blue cathode side of the CRT to an emitter and inputting a blue video signal to the base, and the red Of the beam current detecting Tr, the green beam current detecting Tr, and the collector of the blue beam current detecting Tr are connected, one end of which is connected and the other is grounded, and the red, green, and blue are connected. A beam current detecting resistor for synthesizing the beam currents of the same and converting the beam current into a voltage; an AD converter for converting the beam current waveform converted into the voltage by the beam current detecting resistor into a digital signal;
The maximum value detection circuit that detects the maximum value of the digital signal from the converter for each field in the video signal area and outputs it as the maximum beam current value, the contrast setting value, the beam current detection start time setting value, and the delay time setting value. Input the power-on signal, the maximum beam current value, and the beam current threshold value, and detect when the power-on signal changes from the off state to the on state, and set the beam current detection start time set value after the on state. At the maximum beam current value, and when the maximum beam current value is larger than the beam current threshold value, the contrast adjustment value is once set to a value smaller than the contrast setting value, and then the delay time setting value is set. Gradually increase the contrast adjustment value to the contrast setting value until the set time is reached. If the maximum beam current value is smaller than the beam current threshold value, the contrast adjustment value is set without performing correction on the contrast adjustment value, the processor that outputs the contrast adjustment value, and the contrast adjustment value And a contrast signal that inputs the luminance signal of the video signal, adjusts the gain of the luminance signal according to a contrast adjustment value, and outputs a contrast-adjusted luminance signal output. 2. A red beam current detection Tr having a red cathode side of a CRT connected to an emitter, and a red image signal being input to a base, and a green cathode side of the CRT connected to an emitter to obtain a green image. A green beam current detecting Tr for inputting a signal to the base, a blue beam current detecting Tr for connecting a blue cathode side of the CRT to an emitter and inputting a blue video signal to the base, and the red Of the beam current detecting Tr, the green beam current detecting Tr, and the collector of the blue beam current detecting Tr are connected, one end of which is connected and the other is grounded, and the red, green, and blue are connected. Beam current detecting resistor for synthesizing the beam currents of the above and converting into a voltage, an AD converter for converting the beam current waveform converted into a voltage by the beam current detecting resistor into a digital signal, and a digital signal from the AD converter Maximum beam current detection circuit composed of the maximum value detection circuit that detects the maximum value in the video signal area and outputs it as the maximum beam current value, contrast setting value, minimum contrast adjustment value and beam current detection start time setting value Input the delay time setting value, the power-on signal, the maximum beam current value, and the beam current threshold value, detect that the power-on signal changes from the off state to the on state, and set the contrast setting value as the contrast adjustment value. ,
The contrast setting value and the minimum contrast adjustment value are compared, and if the minimum contrast adjustment value is large, no contrast correction is performed.If the minimum contrast adjustment value is small, the beam current detection start time setting value is set. When the maximum beam current value at the set time is read and the maximum beam current value is larger than the beam current threshold value, the contrast adjustment value is set to the minimum contrast adjustment value, and then the delay time setting is performed. Contrast correction is performed so as to gradually increase the contrast adjustment value to the contrast set value by the time set by the value, and when the maximum beam current value is smaller than the beam current threshold value, the contrast adjustment value The contrast setting value without adjusting the contrast Then, the processor that outputs the contrast adjustment value, and the contrast adjustment value and the luminance signal of the video signal are input, and the gain of the input luminance signal is adjusted by the contrast adjustment value, and the contrast-adjusted luminance is adjusted. A blooming suppression circuit including a contrast circuit that outputs a signal output.