JPH0898107A - Video signal processor and cathode-ray tube driving device - Google Patents

Abstract

PURPOSE: To provide a picture of high stability and high fidelity over a wide band by impressing brightness (BRT) reference signals overlapped with the feedback periods of a video signal on the cathode of a cathode-ray tube and a grid electrode, detecting the beam current of the reference signals from the impression signal and controlling BRT. CONSTITUTION: A current detection part 9 detecting the cathode current of the BRT reference signal and an S/H part 10 which samples/holds (S/H) the peak value of the BRT reference signal by a timing signal from a BRT reference signal generation part 7 are provided. Furthermore a comparator 11 comparing the peak value of the BRT reference signal which is sampled/held with a black level reference signal and outputting the amplitude value of the BRT reference signal and a voltage control part 12 controlling DC voltage by output from the comparator 11 are provided. The signals obtained by overlapping the brightness reference signal with he feedback periods of the input video signals are impressed on the cathode of the cathode-ray tube and the grid electrode, the beam current of the brightness reference signal is detected and the cutoff of the cathode-ray tube is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing of a color television receiver, and an object thereof is to provide a video signal processing device and a cathode ray tube driving device capable of realizing a high-stability and high-fidelity image in a wide band. And

[0002]

2. Description of the Related Art A conventional cathode ray tube driving device applies a video signal to a cathode and a grid electrode of a cathode ray tube as a driving method for realizing a wide band and high brightness with a small amplitude.
A method for performing stable and highly accurate image adjustment by the video drive circuit for CRT disclosed in Japanese Patent Publication No. Hei 3-167965, and detecting the reference signals superimposed in the blanking period of the video signal and performing feedback control. As such, an image adjusting device disclosed in Japanese Patent Laid-Open No. 61-6985 is proposed.

FIG. 25 shows a block diagram of a conventional cathode ray tube driving device. In FIG. 25, 117 is an inverting amplifier, 1
19 is a non-inverting amplifier, 121 and 2 are video output amplifiers,
Reference numeral 147 is a grid electrode of the cathode ray tube 127, and 163 is a cathode electrode similarly.

Next, the operation will be described. The video signal from the input terminal IN has an inverting amplifier 117 and a non-inverting amplifier 119.
And a video signal of both polarities is created. The video signal from the inverting amplifier 117 is supplied to the video output amplifier 121 composed of a cascode amplifier, and the positive video output signal amplified to a level capable of driving the cathode ray tube is applied to the grid electrode. Also, the non-inverting amplifier 11
Similarly, the video signal from 9 also applies the negative video output signal amplified by the video output amplifier 123 to the cathode electrode.

As described above, by applying a bipolar video output signal to the cathode and the grid electrode to drive the cathode ray tube, it is possible to realize a cathode ray tube driving device capable of wide band and high brightness with a small amplitude. .

FIG. 26 shows a block diagram of a conventional video signal processing device. In FIG. 26, 202 is a mixer and 205
Is a gain adjusting circuit, 206 and 212 are sample and hold circuits, 208 and 214 are comparators, and 210 is a video output amplifier.

Next, the operation will be described. Input terminal 20
The video signals from 1, 3, and 4, the contrast adjustment pulse, and the brightness adjustment pulse are supplied to the mixer 202, and various pulses are mixed during the blanking period of the video signal. Mixer 2
The mixed video signal from 02 is a gain adjustment circuit 205.
A contrast adjustment pulse is detected by the contrast feedback control loop composed of the sample hold circuit 206 and the comparator 208, and the gain adjustment is performed. Gain adjustment circuit 2
The gain-adjusted signal from 05 is the video output amplifier 21.
The video output signal supplied to 0 and amplified to a level capable of driving the cathode ray tube 211 is applied to the cathode electrode. Video output amplifier 210 and sample hold circuit 2
The cutoff adjustment is performed by controlling the DC potential of the grid electrode of the cathode ray tube so that the beam current of the brightness adjusting pulse is detected by the brightness feedback control loop composed of 12 and the comparator 214 so that the beam current is always constant. Be seen.

As described above, by performing feedback control so that the voltage values of the contrast and brightness adjusting pulses are always fixed to the reference voltage, stable contrast and cutoff can be controlled, and stable images can be obtained. A signal processing device can be realized.

[0009]

However, in the above-mentioned configuration, by driving the cathode and the grid in parallel, it is possible to easily realize a wide band, low power consumption, and miniaturization, but it is difficult to achieve each of the cathode ray tubes. There is a problem in that the chromaticity of the image fluctuates significantly due to the different emission characteristics of each electrode. Further, particularly in a CRT projection type display for displaying a large screen, there is a problem that chromaticity fluctuation becomes extremely large as compared with the direct-view type because saturation of phosphor emission characteristics occurs.

Further, in order to stabilize the chromaticity, it is necessary to perform a complex gradation correction by applying a digital technique. For this reason, the circuit scale is extremely large due to the increase in processing speed and the increase in the number of quantization bits. However, it has a problem in that wide band processing cannot be realized in terms of performance and reliability.

In view of the above point, the present invention detects each reference signal superimposed in the blanking period of a video signal and performs various controls to stabilize chromaticity in parallel driving and to obtain high stability and high stability in a wide band. An object of the present invention is to provide a video signal processing device and a cathode ray drive device that can realize a faithful image.

[0012]

A first invention is to superimpose a brightness reference signal in a blanking period of an input video signal, and to superimpose the signal superposed by the superimposing means on a cathode and a grid electrode of a cathode ray tube. Applying means for applying, detecting means for detecting the beam current of the brightness reference signal from the applied signal of the cathode electrode applying means, and control means for controlling the cutoff of the cathode ray tube based on the BRT reference signal from the detecting means. Is equipped with.

A second aspect of the invention is to superimpose a brightness reference signal and a contrast reference signal in a blanking period of an input video signal, and to apply the signal superposed by the superimposing means to a cathode and a grid electrode of a cathode ray tube. Applying means, detecting means for detecting the beam current of each of the reference signals from the applied signal of the cathode electrode applying means, and first control means for performing contrast feedback control based on the contrast reference signal from the detecting means. And a second control means for performing brightness feedback control based on the brightness reference signal from the detection means.

According to a third aspect of the present invention, a superimposing means for superimposing the brightness reference signal and the contrast reference signal in the blanking period of the input video signal, and a gamma for performing non-linear processing on the signal from the superimposing means based on the brightness reference signal. Correction means, application means for applying the signal from the gamma correction means to the cathode and grid electrode of the cathode ray tube, detection means for detecting the beam current of each of the reference signals from the applied signal of the cathode electrode application means, and It is provided with first control means for performing contrast control based on the contrast reference signal from the detection means, and second control means for performing brightness control based on the brightness reference signal from the detection means.

According to a fourth aspect of the invention, there is provided a frequency separating means for separating an input video signal into a low frequency component and a high frequency component, and the low frequency component from the frequency separating means to a cathode electrode of a cathode ray tube.
It is provided with an application means for applying the high frequency component to the grid electrode of the cathode ray tube.

According to a fifth aspect of the present invention, frequency detecting means for detecting a scanning frequency of the input signal, control means for controlling the amplitude or frequency component of the input video signal by the detection signal from the frequency detecting means, and the control means are provided. It is provided with an application means for applying the signal of (1) to the cathode and grid electrode of the cathode ray tube.

[0017]

According to the first aspect of the present invention, a signal in which the brightness reference signal is superimposed is applied to the cathode and the grid electrode of the cathode ray tube during the blanking period of the video signal, and the cathode current is detected by detecting the beam current of the brightness reference signal. By controlling the cutoff of the tube, it is possible to drive the cathode and the grid electrode in parallel, so that it is possible to easily realize a wide band of the video output section.

According to the second invention, a signal obtained by superimposing the brightness and the contrast reference signal is applied to the cathode and the grid electrode of the cathode ray tube during the blanking period of the video signal, and the beam current of each of the reference signals is detected. By controlling the contrast and brightness by using the above, parallel driving with good chromaticity tracking can be realized.

According to the third aspect of the invention, nonlinear processing is performed based on the brightness and the contrast reference signal superimposed in the blanking period of the video signal and applied to the cathode and the grid electrode of the cathode ray tube, and at the same time, each of the reference signals is changed. By detecting the beam current and controlling the contrast and brightness, it is possible to achieve high-accuracy gamma correction with good tracking, and since parallel drive is possible, it is easy to increase the amplitude of the video output section and widen the band. it can.

According to the fourth aspect of the invention, by applying the two-system video signals separated from the input video signal into the low-frequency component and the high-frequency component to the cathode and the grid electrode for driving, the parallel driving is performed. The chromaticity change can be reduced.

According to the fifth aspect of the invention, by controlling the driving of the cathode electrode and the parallel driving of the cathode and the grid electrode according to the input scanning frequency, the gradation property at the time of image display and the wide band at the time of character display can be obtained. Can be easily realized, and optimal video display according to signal specifications and performance can be performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A video signal processing apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of a video signal processing device according to a first embodiment of the present invention.

In FIG. 1, 1 is a contrast (hereinafter C
An input terminal to which an image adjustment signal such as a control signal is supplied, 2 is an input terminal to which a video signal is supplied, 3 is an input terminal to which a brightness control signal is supplied, and 4 is an input to which a synchronization signal is supplied. Terminal 7 is a BRT that generates a brightness (hereinafter abbreviated as BRT) reference signal during the vertical blanking period.
Reference signal generating unit, 5 is a superimposing unit that superimposes the BRT reference signal on a video signal, 6 is an amplifying unit that varies the gain according to an image adjustment signal from the input terminal 1, and 9 is a cathode current of the BRT reference signal. The current detecting unit 10, a sample / hold unit (hereinafter abbreviated as S / H) for sampling / holding the peak value of the BRT reference signal according to the timing signal from the BRT reference signal generating unit 7, and 11 for the sample / hold. -A comparator that compares the peak value of the BRT reference signal that has been dropped with the black level reference signal and outputs the amplitude value of the BRT reference signal, 1
Reference numeral 2 is a voltage control unit that controls the DC voltage by the output from the comparator 11.

The operation of the video signal processing apparatus of the first embodiment constructed as described above will be described below with reference to the operation waveform diagram of FIG. 2A shows a video signal supplied to the input terminal 2, and FIG. 2B shows a vertical synchronization signal supplied to the input terminal 4 in synchronization with the deflection.

The BRT reference signal generator 7 produces the BRT reference signal shown in FIG. 2C from the signal system vertical retrace line period of the video signal of FIG. 2A and the deflection system vertical retrace line period of FIG. 2B. Creating. The peak value of the BRT reference signal is the BR value from the input terminal 3.
It is controlled by the T control signal. The BRT reference signal shown in FIG. 2 (c) is generated in the signal system vertical blanking period shown in FIG. 2 (a).
The reference signal is generated during the period other than the deflection system vertical retrace period. This is because the beam current of the cathode current of the BRT reference signal is detected in the subsequent stage.

The BRT reference signal from the BRT reference signal generator 7 and the video signal are superimposed on each other by the superimposing unit 5 composed of an analog switch or the like, and as shown in FIG.
The reference signal is superimposed. The signal from the superposition unit 5 is amplified by the amplification unit 6 including a cascode amplification circuit and then supplied to the current detection unit 9. The current detector 9 detects the cathode current of the BRT reference signal superimposed in the signal system vertical blanking period, and the negative video output signal shown in FIG. 2 (e) is the cathode of the first electrode of the cathode ray tube. It is applied to an electrode (hereinafter abbreviated as K electrode). The positive video output signal shown in FIG. 2F from the amplifier 6 is applied to the first grid electrode (hereinafter abbreviated as G1 electrode) which is the second electrode of the cathode ray tube. The signal current / voltage converted by the current detector 9 is S /
In the H section 10, the level of the BRT reference signal is set to S / H in FIG.
It is sampled / held by a pulse and converted to a DC potential.

The signal from the S / H unit 10 is supplied to the comparator 11 for comparison with the reference potential, and the comparison output is supplied to the voltage control unit 12. The voltage control unit 12 amplifies the voltage to a necessary voltage for controlling the cutoff of the cathode ray tube and then, as shown in FIG.
The cut-off control signal of the DC potential shown in is output. The cutoff control signal from the voltage controller 12 is applied to, for example, a second grid electrode (hereinafter abbreviated as G2 electrode) which is the third electrode of the cathode ray tube. Therefore, Vs, which is the DC potential of the control signal of FIG. 2G, is changed according to the BRT reference signal, and BRT control can be realized by the acceleration effect in G2.

Next, the waveform diagram of FIG. 3 is used to describe in detail the BRT control method using the G2 electrode. Figure 3
The K waveform voltage applied to the K electrode in (b), (d) and (f) is shown in FIG.
(a), (c) and (e) show the G2 waveform voltage applied to the G2 electrode. When the video signal on which the BRT reference signal is superimposed as shown in FIG. 3B is applied to the K electrode, the beam current of the BRT reference signal is detected and the level is controlled, as shown in FIG. 3B. Such G3 potential VS3 is applied to the G2 electrode.

The pedestal potential (VPE) of the K voltage shown in FIG.
D) is clamped so that it is always constant, and only the amplitude of the video signal is controlled. BR of FIG. 3 (b)
B2 control can be performed by controlling the G2 potential from the peak value of the T reference signal and performing feedback control of the BRT so that the cutoff voltage is always constant.

FIG. 3 (d) is a K waveform when the amplitude of FIG. 3 (b) is halved, and the G2 waveform at this time is shown in FIG. 3 (b) as shown in FIG. 3 (c). Controlled in a higher direction than G2
The potential becomes VS4 (VS3 <VS4).

FIG. 3 (f) is a K waveform when the BRT reference signal of FIG. 3 (b) is the same as the pedestal potential, and the G2 waveform at this time is as shown in FIG. 3 (e). It is controlled to a higher direction than c), and the G2 potential is VS5 (VS3 <VS4 <
VS5). As described in the operation of the BRT control from the relationship between the cathode and the grid waveform with reference to FIG. 3, in the cathode waveform, only the amplitude of the video signal is controlled and the pedestal potential is always constant. And the wide band can be easily realized. The BRT control is not voltage control at the cathode that performs broadband processing, but BRT control can be realized with a simple configuration by controlling the second grid voltage.

Next, in order to explain the BRT control method by G1 in detail, the configuration diagram of FIG. 4 and the waveform diagram of FIG. 5 are used. In FIG. 4, elements performing the same operations as in FIG. 1 are indicated by the same numbers. The positive video output signal from the amplifier 6 and the control signal from the voltage controller 12 are supplied to a clamp circuit 13 composed of a diode clamp circuit or the like, peak-clamped at the peak value of the BLK signal, and the first signal of the cathode ray tube. It is applied to one grid electrode (G1 electrode) to perform BRT control.

FIGS. 5 (a), 5 (c) and 5 (e) show the K waveform voltage, which is a negative image output signal applied to the K electrode, as shown in FIGS.
(f) shows a G1 waveform voltage which is a positive image output signal applied to the G1 electrode. When a video signal on which the BRT reference signal is superimposed as shown in FIG. 5A is applied to the K electrode, the beam current of the BRT reference signal is detected and the BLK level shown in FIG. 5B is controlled. A positive video output signal is applied to the G1 electrode. Therefore, from the peak value of the BRT reference signal in FIG. 5 (a) to the pedestal potential (VGC
The BRT control can be performed by performing feedback control of the BRT so that the cutoff voltage (VCF) up to 1) is always constant.

FIG. 5 (c) is a K waveform when the amplitude of FIG. 5 (c) is halved, and the G1 waveform at this time is shown in FIG. 5 (b) as shown in FIG. 5 (d). Controlled in a higher direction than G2
The potential becomes VGC2 (VGC1 <VGC2).

FIG. 5 (e) is a K waveform when the BRT reference signal of FIG. 5 (a) is made equal to the pedestal potential, and the G1 waveform at this time is as shown in FIG. 5 (f). Compared to b), the G1 potential is controlled to a higher direction and the G1 potential is VGC3 (VGC1 <VGC
2 <VGC3). As described in the operation of the BRT control from the relationship between the cathode and the grid waveform with reference to FIGS. 3 and 5, in the cathode waveform, the pedestal potential is always constant by controlling only the amplitude of the video signal. Large amplitude and wide band can be easily realized. The BRT control is not voltage control at the cathode that performs broadband processing, but BRT control can be realized with a simple configuration by controlling each grid voltage. In the present embodiment, the case where the G1 and G2 electrodes are used as the BRT control has been described. However, when comparing the control by the DC potential in G2 and the control for handling a wide-bandwidth and large-amplitude video signal in G1, when G2 is compared, Needless to say, it is easier and more stable to perform control. Further, since the light emission characteristic with respect to the voltage applied to the G2 electrode becomes almost linear, it is also very advantageous in terms of tracking for each color.

As described above, in this embodiment, a signal obtained by superimposing the brightness reference signal in the blanking period of the input video signal is applied to the cathode and the grid electrode of the cathode ray tube, and the beam current of the brightness reference signal is detected. By controlling the cutoff of the cathode ray tube by using the cathode ray tube, the cathode and the grid electrode can be driven in parallel, so that the band of the video output signal applied to each electrode can be easily realized.

Next, a video signal processing device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram of a video signal processing device according to the second embodiment of the present invention.

In FIG. 6, 14 is a superimposing section for superimposing a reference signal on a video signal, and 15 is a BRT reference signal and CONT.
A reference signal generator for generating a reference signal, 16 an input terminal for supplying a CONT reference signal for controlling contrast, 17 a variable gain amplifier for varying the gain of the video signal, 17 a pedestal period of the video signal Clamp part for direct current reproduction at 19, S / H part for sample-holding the peak value of the contrast reference signal, 20 at the amplitude value of the contrast reference signal by comparing the crest value of the contrast reference signal and the black level reference signal Comparator for outputting
IN reference potential input terminals, 22a and 22b are samples /
Hold pulse 1 and 2 (S / H pulse 1 and 2) input terminals, 23a and 23b are video output units for amplifying video signals to a level for driving a cathode ray tube cathode, and 24 is B
This is an input terminal for the IAS reference potential. It should be noted that the same operations as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The operation of the video signal processing apparatus of the second embodiment constructed as above will be described below with reference to the operation waveform chart of FIG. 7A shows the video signal supplied to the input terminal 2, and FIG. 7B shows the vertical synchronization signal supplied to the input terminal 4 in synchronization with the deflection.

In the reference signal generator 15, the reference system signal blanking period shown in FIG. 7 (a) and the deflection system vertical blanking period shown in FIG. 7) and the CONT reference signal shown in FIG. 7D. The peak value of the BRT reference signal is controlled by the control signal from the input terminal 3, and the peak value of the CONT reference signal is controlled by the control signal from the input terminal 16. The BRT reference signal, the CONT reference signal, and the video signal from the reference signal generation unit 15 are added by the superposition unit 14, and the video signal on which each reference signal is superposed is output as shown in FIG.

The signal from the superposing unit 14 is supplied to the clamp unit 18 through the variable gain control unit 17 composed of a balanced modulation type differential amplifier and the like, and is pedestal clamped during the pedestal period of the video signal. The signal from the clamp unit 18 is sent to the S / H unit 19 to determine the level of the H.CONT reference signal.
S / H pulse 1 of (g) is sampled / held and converted to a DC potential. The signal from the S / H unit 19 is the comparator 20.
And is compared with the GAIN reference potential from the input terminal 21. The comparison output is a variable gain controller 17
And the feedback control of the first contrast is performed so that the peak value of the H.CONT reference signal always has a constant amplitude.

The signal from the clamp unit 18 is the image output unit 2
It is supplied to the current detector 9 through 3a. Current detector 9
Then, the beam currents of the BRT and V.CONT reference signals superimposed in the vertical blanking period are detected, and the negative video output signal of FIG. 7 (h) is applied to the K electrode.

First, the operation of BRT control will be described.
The current / voltage converted signal from the current detector 9 is S / H.
In the section 10, the level of the BRT reference signal is sampled / held by the S / H pulse 2 of FIG. 7 (f) and converted into a DC potential. The signal from the S / H unit 10 is supplied to the comparator 11 for comparison with the BIAS reference potential, and the comparison output is supplied to the voltage control unit 12. The voltage control unit 12 generates a voltage for controlling the cutoff of the cathode ray tube. The control voltage from the voltage control unit 12 and the negative video output signal from the video output unit 23b are supplied to the clamp unit 13, and the peak value of the BLK signal of the negative video output signal is the voltage control unit 12.
The image output signal of FIG. 7 (i) is applied to the G1 electrode after being peak-clamped so as to be set to the control voltage.
In this way, by inputting the current detection signal of the BRT reference signal to the clamp unit 13 and performing the current feedback type DC reproduction, the BRT control is performed so that the level of the BRT reference signal is always a constant black level.

Next, the operation of the second contrast control will be described. V. within the vertical blanking period superimposed by the above method.
The CONT reference signal is converted from current / voltage from the current detection unit 9, and this signal is converted into S / by the timing signal of FIG. 7 (f).
The H section 10 samples / holds the peak value. S
The output from the / H unit 10 is supplied to the GAIN reference potential of the comparator 20 to obtain the amplitude value of the contrast reference signal. By inputting this amplitude value to the variable gain amplifying section 17 to perform the current feedback type gain control, the stable second signal of the video signal is always maintained so that the beam current of the peak value of the V.CONT reference signal is always the reference value. Feedback control of the contrast is performed.

In order to explain this contrast control in detail, the operation waveform diagram of FIG. 8 and the configuration diagram of FIG. 9 are used. Figure 8 (a)
As shown in (c) and (e), in the first contrast control of this embodiment, when the current feedback control is performed by changing the level of the H.CONT reference signal, the output waveform thereof is as shown in FIG. )
As shown in (d) and (f). That is, the voltage feedback type first contrast control including the variable gain amplifying unit 17, the clamp unit 18, the S / H 19, and the comparator 19 is performed so that the peak value VCONT of the H.CONT reference signal is always constant. Be seen.

The second contrast control is H.CO
The beam currents of V.CONT and the BRT reference signal set to the same level as the NT reference signal and the black reference signal described later are detected by the current detection unit 9, and the S / H 10a outputs the BRT reference signal and the S / Hb outputs the black reference. Signal, S / Hc V.CONT
The peak value of the reference signal is sampled and held. S / H1
The signals from 0a to 0c are V.CONT level detection circuits 26.
Is supplied to the black reference beam current value iPED to V.CONT.
The beam current ib up to the reference beam current iCONT is calculated. As shown in FIG. 8B, when the BRT reference signal and the V.CONT reference signal are in the same direction, the BRT reference beam current i
The beam current ib1 obtained by adding the BRT and the V.CONT beam current iCONT is detected. If the black reference signal and the BRT reference signal are set to the same level as shown in FIG.
The beam current i obtained by adding the reference beam current iBRT or the black reference beam current iPED and the V.CONT beam current iCONT.
b2 is detected. When the BRT reference signal and the V.CONT reference signal are in opposite directions as shown in FIG. 8F, the beam current ib3 obtained by adding the black reference beam current iPED and the V.CONT beam current iCONT is detected. The V.CONT level detection circuit 26 controls the arithmetic processing by adjusting the V.V. The beam current value ib up to the CONT reference signal is calculated. The detection signal from the V.CONT level detection circuit 26 is supplied to the adder 25 in the first feedback control pool. The adder 25 is S / H19
From the V.CONT level detection circuit 26 and the current feedback control detection signal from the V.CONT level detection circuit 26 are added, and then supplied to the input terminal of the comparator 19 for current feedback type second contrast control. Is done.

That is, in the first contrast control, fluctuations and tracking between RGB are taken in the circuit system, and in the second contrast control, fluctuations in the image output section and changes with time in the cathode ray tube are corrected.

Next, the operation waveform diagram of FIG. 8 is used to explain the operation in the case of superposing the black level (hereinafter abbreviated as B) reference signal together with various reference signals in this superposing section. This B reference signal is used as a reference signal for detecting the peak value of the CONT and BRT reference signals, and the CONT reference superimposed on FIG. 8 (a) within the period of the horizontal blanking period signal shown in FIG. 8 (g). The signal and the B reference signal shown in FIG. 6 (h) are superimposed. Figure 6
As shown in (a), the level of the B reference signal is set to the same level as the pedestal level. With this B reference signal as a reference, the peak values of the CONT reference signal and the BRT reference signal can be stably detected.

First, the operation of detecting the peak value of the CONT reference signal will be described below. The crest value of the CONT reference signal superposed by the above method is sampled / held by the first S / H circuit. Further, the B reference signal superposed as a set with the CONT reference signal is sampled / held by the second S / H circuit. Since the amplitude information of the CONT reference signal is necessary to control the gain of the variable gain control unit, the first and second S / H
The first comparator compares the difference between the outputs of the circuits to obtain the amplitude value of the CONT reference signal.

The operation of detecting the peak value of the BRT reference signal will be described below. In the brightness control, that is, the DC reproduction operation, first, the peak value of the BRT reference signal shown in FIG. 8A is sampled / held by the third S / H circuit. Further, the B reference signal in the horizontal blanking period shown in FIG. 8 (h), which is superposed as a set with the BRT reference signal, is sampled / held by the fourth S / H unit 12. The difference between the peak values of the B reference signal and the BRT reference signal is obtained by the second comparing section, and the amplitude value of the BRT reference signal is obtained.

As described above, the amplitude information of the reference signal is required to control the contrast and brightness. That is, the black level standard is absolutely necessary. Therefore, as in the present embodiment, the image adjustment reference signal and the B reference signal are set as one set, and the image signals are superimposed, so that the image adjustment is performed with respect to an arbitrary synchronization signal phase, a blanking period, that is, an arbitrary input image signal. The peak value of the reference signal and the black level reference signal can be sampled / held reliably, and the amplitude information of the image adjustment reference signal can be reliably captured. As a result, reliable operation of the feedback loop for contrast control and brightness control can be guaranteed, and a highly stable video signal processing device compatible with multimedia can be realized.

Next, the case of performing white balance adjustment will be described. The white balance adjustment is to correct the color balance for each gradation due to the emission characteristics of the cathode ray tube. The emission characteristics of the cathode ray tube are not generally uniform in RGB, and the relationship between the input signal and the brightness of the output screen is different as shown in FIG. 10. Therefore, even if the same signal is input, the image brightness is different in RGB. . Therefore, in order to make the brightness of the display screen uniform, it is necessary to adjust the gain of the video signal and the G1 potential by RGB as shown in FIG. This adjustment is the gain and bias adjustment of the white balance adjustment.

When adjusting the low light in the vicinity of black for bias adjustment, a test signal of 0% or 25% of the black level signal is displayed, and the low light in the vicinity of black is controlled by the bias (BIAS) control signal of the input terminal 24. Adjust the white balance of. To correct the highlight near white in the gain adjustment, project a test signal of 75% or 100% of the white level signal and adjust the white balance near white by the gain (GAIN) control signal of the input terminal 21. It can be realized by doing.

Next, in order to describe the white balance in the case of applying a negative image output signal to K and a positive image output signal to G1, the light emission characteristic diagram of FIG. 12 is used. FIG. 12A shows a light emission characteristic when a video signal is applied to one of K and G1 as in the conventional case. In FIG. 12 (a), the dashed line shows the light emission characteristics when K is applied, and the solid line shows the light emission characteristics when G1 is applied.
It can be seen that when 1 is applied, the characteristic becomes non-linear. Figure 12 (b)
It can be seen that the non-linear characteristic caused by the application of G1 in FIG. 12A is generated as it is, as shown in the emission characteristics when the video signal is applied to K and G1.

As described above, the parallel driving of K and G1 makes the emission characteristics of the cathode ray tube non-linear, which makes the white balance adjustment much more complicated than the conventional one.

In consideration of the above points, the BRT reference signal is used as the beam current detection signal near the black level (cathode current iBRT = 5 μA) as shown in the emission characteristics of cathode current: brightness in FIG. 12C. Using the V.CONT reference signal as the beam current detection signal near the intermediate level (beam current iCONT = 100 μA), the RGB feedback emission characteristics are automatically adjusted by performing the current feedback control, and the color is adjusted. We are trying to stabilize the degree.

As described above, in this embodiment, a signal in which the brightness reference signal and the contrast reference signal are superposed is applied to the cathode and the grid electrode of the cathode ray tube during the blanking period of the input video signal, and the beam of each reference signal is applied. By detecting the current and controlling the contrast and brightness, good chromaticity tracking array drive can be guaranteed,
A highly stable video signal processing device can be realized.

Next, a video signal processing device according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 13 is a block diagram of a video signal processing device in the third embodiment of the present invention.

In FIG. 13, reference numeral 27 is a gamma correction unit for performing gamma correction based on the BRT reference signal. In addition,
The same elements as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted. The signal from the variable gain control unit 17 is supplied to the gamma correction unit 27 and clamped in the BRT reference signal period, and then a gamma correction circuit (not shown) configured by a non-linear amplifier using non-linear characteristics of transistors and diodes. Gamma correction is performed in (No.). Since the first and second CONT controls and BRT control are the same as those in the second embodiment, the gamma correction operation will be described here.

First, the gamma correction operation related to the BRT control will be described in detail with reference to the waveform chart of FIG. FIG. 14A shows a video signal on which the BRT reference signal input to the gamma correction unit 25 is superimposed, and the BRT reference signal is set to the maximum (max), standard (typ), and minimum (min). The output characteristics are shown in FIGS. 14 (b) (c) (d). FIG. 14B shows a lamp output waveform when the BRT setting condition is standard (typ), and the non-linear processing is performed from 75% of the signal average value. FIG. 14B shows a lamp output waveform when the BRT setting condition is maximum (max), and the non-linear processing is performed from 50% of the signal average value. Figure 14 (d) shows B
It is a lamp output waveform when the RT setting condition is the minimum (min), and is automatically set so that the nonlinear processing is performed from 100% of the signal average value.

That is, by superimposing the BRT reference signal on the video signal and performing the gamma correction according to the level on the BRT reference signal, highly accurate gamma correction can be realized. Figure 1
As shown in the emission characteristics of a video projector that performs a large-screen display using the RGB projection tube of No. 5, it is very suitable for gamma correction especially when saturation occurs in the emission characteristics of the B phosphor in the large current region. There is.

Next, the gamma correction operation related to the CONT control will be described in detail with reference to the waveform chart of FIG.
As shown in the configuration diagram of FIG. 13, the voltage feedback type first CONT control is performed before gamma correction and the current feedback type second CONT control is performed after gamma correction. Figure 14 (a)
, Which is a signal input to the gamma correction unit 27, is superimposed with various reference signals, and V. C
The peak values of the ONT reference signal and the H.CONT reference signal for voltage feedback control are equal. BR in Fig. 16 (b)
The T setting condition is the lamp output waveform after gamma correction at the maximum (max), and the non-linear processing is performed from 40% of the signal average value. The peak value of the CONT reference signal before gamma correction in FIG. 14A is VGAM and the peak value of the CONT reference signal after gamma correction in FIG. 14B is Δ with respect to the peak value VGAM before correction.
The VGAMMA component becomes large. The second CONT is detected by detecting the beam current of the peak value in which the ΔVGAMMA component is larger than the peak value VGAM of the CONT reference signal.
Stable gamma correction can be realized by controlling.

As described in the second embodiment, the amplitude of the reference signal for detection is stabilized by the first contrast control, and the beam current of the reference signal having the constant amplitude is detected to detect the image output section or the cathode ray tube. The gamma correction with high accuracy is performed by performing the change caused by the second contrast control.

In this embodiment, since the gamma characteristic of the phosphor shown in FIG. 15 is determined in advance, the gamma correction circuit having a fixed non-linear characteristic is used for the correction.
The case where the gamma correction is performed by detecting the reference signal and controlling the cutoff and the gain has been described. However, if the gamma correction circuit can create an arbitrary non-linear characteristic, the detection signal is directly fed back to the gamma correction section for correction. As described above, in the present embodiment, the nonlinear processing is performed based on the brightness and the contrast reference signal superimposed in the blanking period of the video signal and applied to the cathode and the grid electrode of the cathode ray tube. By detecting the beam current of the reference signal and controlling the contrast and brightness, high-accuracy gamma correction can be realized with good tracking, and since parallel driving is possible, it is possible to easily realize a wide band of the video output section. .

Next, a cathode ray drive device according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 17 is a block diagram of a cathode ray tube driving device according to the fourth embodiment of the present invention.

In FIG. 17, 40 is a high-pass filter for extracting the high-frequency component of the video signal, 36 is a low-pass filter for extracting the low-frequency component of the video signal, and 33 is the cathode ray tube 35. One electrode is a cathode electrode, and 34 is a second electrode, which is a grid electrode. The same operations as those in the first to third embodiments are designated by the same reference numerals and the description thereof will be omitted.

The operation of the cathode ray tube driving device of the fourth embodiment constructed as described above will be described below with reference to the characteristic diagram of FIG. Note that FIG. 19 shows a specific configuration diagram of the high-pass filter 40 and the low-pass filter 36 for extracting the high band and the low band of the video signal. A signal having a high cutoff frequency (fCS) shown in FIG. 19A is supplied to the input terminal 2 to the low pass filter 36 and the subtractor 37. The low-pass filter 36 has the frequency characteristic of the low cutoff frequency (fC1) shown in FIG. 18B, and the signal of the low-pass component from the low-pass filter 36 is supplied to the video output unit 23b.
After amplification, it is applied to the cathode electrode. Also, FIG. 18 (a)
The input signal having the characteristic shown in FIG. 18 and the signal from the low-pass filter 36 having the characteristic shown in FIG. Is output. The high frequency component signal from the subtractor 37 is supplied to the video output unit 23b, amplified and applied to the grid electrode, and added by the electron beam on the cathode ray tube.
The display screen of the characteristic shown in (d) is displayed.

Next, the reason why the low frequency component is applied to the cathode electrode and the high frequency component is applied to the grid electrode will be described. 12
As described above, the linear emission characteristic is obtained when K is applied, and the linear emission characteristic is obtained when G is applied. This means that the gradation is lost (change in chromaticity) when G is applied. Generally, a detection source of human chromaticity change is more noticeable as a low-frequency signal and less noticeable as a high-frequency signal.

For the above reason, in the two-electrode drive, the low-frequency component whose chromaticity change detection source is high is applied to the cathode electrode having the linear emission characteristic, and the high-frequency component whose chromaticity change detection source is low is the nonlinear emission characteristic. By applying to the grid electrode, it is possible to significantly reduce the change in chromaticity when driving two electrodes.

Further, in order to correct the fluctuation and the change with time in the drive system and the cathode ray tube in the two-electrode drive, further improvement can be made by incorporating the contents of the first to third embodiments.

As described above, the chromaticity changes during parallel driving by applying the two-system video signals separated from the input video signal into the low-frequency and high-frequency components to the cathode and the grid electrode to drive them. Can be reduced.

Next, a cathode ray drive device according to a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 23 is a block diagram of a cathode ray tube driving device according to the fifth embodiment of the present invention.

In FIG. 17, reference numerals 31 and 32 denote a gain control circuit for controlling the polarity, amplitude and band of the video signal, and 30 denotes a scanning frequency detector for detecting the scanning frequency from the input signal from the input terminal 2. is there. In addition, first to
Those performing the same operations as in the fourth embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the cathode ray tube driving device of the fifth embodiment having the above-mentioned structure, the relationship diagram of FIG. 21 and FIG.
The operation will be described with reference to the operation waveform diagram of FIG. FIG. 21 shows a relationship diagram between the horizontal scanning frequency and the required band. The horizontal scanning frequency and the required band are in a proportional relationship as indicated by the solid line. Also N
It can be seen that the image display of TSC or HD (high definition) (broken line) is distributed in the low scanning frequency region, and the character display of computers and the like (dotted line) is distributed in the high scanning frequency region.

In FIGS. 22A and 22D, video signals (tH1> tH2) having different scanning frequencies are input to the input terminal 2 and supplied to the gain control circuits 31 and 32 and the scanning frequency detecting section 30.
The scanning frequency detection unit 30 is composed of a counter circuit, and the horizontal scanning frequency is detected by comparison with the reference clock signal. The detection signal from the scanning frequency detection unit 30 is supplied to the gain control circuits 31 and 32 to control the polarity, amplitude and band of the video signal.

In the image display signal of FIG. 22A, the gain control circuit 31 on the grid electrode 34 side is turned off and the gain control circuit 32 on the cathode electrode 33 is turned on. Therefore, the negative image output signal shown in FIG. 22D is applied to the cathode electrode 22, and the DC potential shown in FIG. 22C is applied to the grid electrode 34.

In the character display signal of FIG. 22 (d), the gain control circuit 31 on the grid electrode 34 side and the cathode electrode 33 side,
Both are turned on to 32. Therefore, the negative polarity video output signal shown in FIG. 22E is applied to the cathode electrode 22, and the positive polarity video output signal shown in FIG. 22F is applied to the grid electrode 34. 22 (d) (c) and (e) (f) show the relationship of the potentials actually applied. The cathode applied voltage is a positive potential, the grid applied voltage is a negative potential, and an intermediate 0V potential exists. Have a relationship to

That is, when the scanning frequency detected by the scanning frequency detecting unit 30 is lower than the horizontal scanning frequency fH1 shown in FIG. 21, the cathode electrode is driven, and when it is higher, the cathode and the grid electrode are driven so that the gain control is performed. Circuit 3
1, 32 are controlled.

Since the performance required for the display is different between the image display and the character display, as described with reference to FIG. 12, the electrode drive system is focused on the gradation in the image display and in the band and the rising / falling characteristics in the character display. The operation is controlled so that Since the drive voltage for driving the cathode electrode is about twice as large as that for driving the cathode and the grid electrode in parallel, the power supply voltage of the video output unit is controlled to be set high.

The case where the application operation is forcibly operated / stopped so that the one-electrode drive is performed when the scanning frequency is low and the two-electrode drive is performed when the scanning frequency is high has been described above. In order to explain the case of controlling the amplitude ratio of the applied signal during driving, the operation waveform diagram of FIG. 23 and the emission characteristic diagram of the 7-type projection tube of FIG. 24 are used.
FIG. 24 shows a typical projection display 7
As shown in the light emission characteristics of the mold projection tube when K and G are applied, the sensitivity when K is applied is about 40% better than when G is applied, and the curve of the light emission characteristics is better than the linear characteristics when K is applied. When G is applied, the characteristic becomes linear. In FIGS. 23 (a) and 23 (b), video output signals (VK10, = VG1) of the same amplitude are applied to the cathode and the grid electrode.
Each applied waveform when 0) is applied is shown. The cutoff voltage (VCF) of each applied signal up to the pedestal potential (VPED to -VPED) is applied so that it is always constant. From the light emission characteristics of FIG. 24, in order to make the light emission sensitivities during K application and G application the same, the G applied signal must be set to be about 40% larger than the K applied signal. As shown in FIGS. 23 (c) and 23 (d), which show the respective applied signals when the sensitivity is the same, the G signal amplitude (VK11 <VG11) is about 40% larger than the K signal amplitude (VK11). To be done.

Since gradation is important when displaying an image, the K application condition of the linear emission characteristic is more advantageous. Therefore, as shown in FIGS. (V
By setting the amplitude ratio so that a signal whose K12) is larger than the G signal amplitude (VK121> VG12) is applied, it is possible to display an image with excellent gradation.

As described above, in the image display with a low scanning frequency, the K application amplitude is set to be large with emphasis on the gradation, and with the character display with a high scanning frequency, the band and the rising / falling characteristics are emphasized and K and G are set. The amplitude ratio is set so that the applied amplitudes are almost equal or the same as the light emission sensitivity.

The control of the bandwidth of the applied signal during the driving of the two electrodes is the same as that of the fourth embodiment, so the description thereof is omitted. Since the width is required, wide band and high brightness can be easily realized by applying the wide band signal shown in FIG. 18A to the cathode and the grid electrode.

Further, in order to correct the fluctuation and the change with time in the drive system and the cathode ray tube in the two-electrode driving, the contents can be further improved by incorporating the contents of the first to third embodiments.

As described above, by controlling the cathode electrode drive and the parallel drive of the cathode and the grid electrode according to the input scanning frequency, and controlling the amplitude ratio and frequency component of the applied signal, the floor at the time of image display can be controlled. The tonality and wide band for character display can be easily realized, and optimal video display according to signal specifications and performance becomes possible.

In this embodiment, the video signal processing of the color television receiver has been described, but the same applies to other video signal processing. Further, in the present embodiment, the case where the reference signal is superimposed within the blanking period has been described, but any other period may be used as long as it is not affected by the video signal.

Further, in this embodiment, a cathode ray tube is used for the first
Although the case where the electrode is applied to the cathode electrode and the second electrode is applied to the first grid electrode has been described, it may be applied to other electrodes. Further, in the present embodiment, the case where the BRT control is performed by controlling the DC potential applied to the first grid electrode or the second grid electrode which is the second electrode has been described, but the DC potential is applied to the cathode electrode and other electrodes. May be applied.

Further, in the present embodiment, in order to make the explanation easy to understand, the case where the bipolar video output signal on which the reference signal is superimposed is applied to the first and second electrodes to perform the feedback control has been described. Feedback control may be performed by removing the reference signal or forcibly setting the other level to the other level.
Further, in the present embodiment, the case where the current detection type feedback control is performed in the state where the detection reference signal is always displayed on the screen has been described, but the detection reference signal is displayed only periodically or when image adjustment is performed. It may be a system for performing feedback control to be issued.

In this embodiment, the beam current of each reference signal is detected from the applied signal applied to the cathode electrode, but the beam current is detected from the signals applied to the other electrodes. Good.

In the first embodiment, the case where the video signal is applied to the cathode electrode and the BRT control signal is applied to the grid electrode has been described, but the reverse may be applied.

In the second embodiment, the case where the CONT feedback control loop is performed with the signal from the input of the output amplifier has been described, but the feedback control may be performed with the signal from the output of the output amplifier.

In the third embodiment, the case where a non-linear amplifier circuit is used as the gamma correction circuit has been described, but a polygonal line approximation circuit having several other points may be used.

In the fourth embodiment, the case where the frequency components of the video signal are separated has been described, but the amplitude ratio may be controlled.

Further, in the fifth embodiment, the case where the horizontal scanning frequency is detected and various controls are performed as the means for performing the signal determination has been described. However, it may be performed by the number of scanning lines, the signal band or a control signal from the outside. Good.

[0095]

As described above, according to the first aspect of the present invention, a signal in which the brightness reference signal is superimposed during the blanking period of the video signal is applied to the cathode and the grid electrode of the cathode ray tube, and the brightness reference signal By detecting the beam current and controlling the cutoff of the cathode ray tube, it is possible to realize brightness control with good tracking during parallel driving.

According to the second invention, a signal in which brightness and contrast reference signals are superimposed is applied to the cathode and the grid electrode of the cathode ray tube during the blanking period of the video signal, and the beam current of each of the reference signals is detected. By controlling the contrast and brightness in this manner, both electrodes can be driven with good chromaticity tracking and high stability can be realized.
Further, highly stable processing can be realized even with respect to changes over time in the cathode ray tube and drive system and changes due to temperature characteristics.

According to the third aspect of the invention, nonlinear processing is performed on the basis of the brightness and the contrast reference signal superimposed in the blanking period of the video signal and applied to the cathode and the grid electrode of the cathode ray tube, and each of the reference signals is also applied. By controlling the contrast and brightness by detecting the beam current of, the gamma correction with good tracking can be realized with high accuracy, and the parallel drive can be performed, so that it is easy to increase the amplitude and wide band of the video output section. realizable. Especially CR
This is a very effective means in a projection display that uses T in a large current region and performs a large amplitude operation.

According to the fourth aspect of the present invention, by applying two systems of video signals, which are separated from the input video signal into low and high frequency components, to the cathode and grid electrodes for driving, parallel driving is possible. It is possible to reduce the change in chromaticity.

According to the fifth aspect of the invention, the image display is achieved by controlling the driving of the cathode electrode and the parallel driving of the cathode and the grid electrode according to the input scanning frequency, and by controlling the amplitude ratio and frequency component of the applied signal. It is possible to easily realize gradation in time and wide band in character display, and it is possible to display the optimum image according to the signal specifications and performance, and the practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a video signal processing device according to a first embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the embodiment.

FIG. 3 is a waveform diagram for explaining a first brightness control operation of the same embodiment.

FIG. 4 is a block diagram for explaining a first brightness control operation of the same embodiment.

FIG. 5 is a waveform diagram for explaining a second brightness control operation of the same embodiment.

FIG. 6 is a block diagram of a video signal processing device according to a second embodiment of the present invention.

FIG. 7 is a waveform chart for explaining the operation of the embodiment.

FIG. 8 is a waveform diagram for explaining the contrast control operation of the same embodiment.

FIG. 9 is a block diagram for explaining a contrast control operation of the embodiment.

FIG. 10 is a relational diagram of the brightness of the input signal and the output screen for explaining the operation of the embodiment.

FIG. 11 is a relationship diagram of a gain and a bias for explaining the operation of the embodiment.

FIG. 12 is a relationship diagram of the brightness of the input signal and the output screen for explaining the operation of the embodiment.

FIG. 13 is a block diagram of a video signal processing device according to a third embodiment of the present invention.

FIG. 14 is a waveform diagram for explaining a gamma correction operation of the same embodiment.

FIG. 15 is a characteristic diagram for explaining a gamma correction operation of the same embodiment.

FIG. 16 is a waveform diagram for explaining a gamma correction operation of the same embodiment.

FIG. 17 is a block diagram of a cathode ray tube driving device according to a fourth embodiment of the present invention.

FIG. 18 is a characteristic diagram for explaining the band control operation of the embodiment.

FIG. 19 is a block diagram for explaining the band control operation of the embodiment.

FIG. 20 is a block diagram of a cathode ray tube driving device according to a fifth embodiment of the present invention.

FIG. 21 is a relational diagram for explaining the same embodiment.

FIG. 22 is a waveform chart for explaining the operation of the embodiment.

FIG. 23 is a waveform chart for explaining an amplitude control operation of the same embodiment.

FIG. 24 is a waveform chart for explaining the amplitude control operation of the same embodiment.

FIG. 25 is a block diagram of a conventional cathode ray tube driving device.

FIG. 26 is a block diagram of a conventional video signal processing device.

[Explanation of symbols]

 5, 14 Superimposition section 7 BRT reference signal generation section 9 Current detection section 10, 19 S / H 11, 20 Comparator 12 Voltage control section 13 Clamp section 15 Reference signal generation section 17 Gain control section 23 Video output section 27 Gamma correction section 30 Scanning Frequency Detector 31, 32 Gain Control Circuit 33 Cathode Electrode 34 Grid Electrode 36 Low Pass Filter 40 High Pass Filter

Claims (14)

[Claims] 1. A superimposing means for superimposing a brightness reference signal during a blanking period of an input video signal, an applying means for applying the signal superimposed by the superimposing means to a cathode and a grid electrode of a cathode ray tube, and the cathode electrode applying. A video signal processing device comprising: a detection means for detecting a beam current of the brightness reference signal from an applied signal of the means; and a control means for controlling the brightness of the cathode ray tube based on the brightness reference signal of the detection means. 2. The video signal processing apparatus according to claim 1, wherein the superimposing means superimposes the brightness reference signal in the vertical blanking period of the input video signal. 3. The video signal processing apparatus according to claim 1, wherein the control means controls the DC potential of the applied signal applied to each electrode. 4. A superimposing means for superimposing a brightness reference signal and a contrast reference signal in a blanking period of an input video signal,
Application means for applying the signal superimposed by the superposition means to the cathode and the grid electrode of the cathode ray tube, detection means for detecting the beam current of each of the reference signals from the application signal of the cathode electrode application means, and the detection means A video signal processing device comprising: first control means for performing contrast control based on a contrast reference signal; and second control means for performing brightness control based on a brightness reference signal of the detection means. 5. A first control means performs voltage feedback control with a first reference signal superimposed in a horizontal blanking period of an input video signal, and a current with a second reference signal superimposed in a vertical blanking period. The video signal processing device according to claim 4, wherein feedback control is performed. 6. The video signal processing apparatus according to claim 4, wherein the second control means controls the DC potential of the applied signal applied to each electrode. 7. A superimposing means for superimposing a brightness reference signal and a contrast reference signal in a blanking period of an input video signal,
Gamma correction means for performing non-linear processing of the signal from the superposition means based on the brightness reference signal, application means for applying the signal from the gamma correction means to the cathode and grid electrodes of the cathode ray tube, and the cathode electrode application means. Detecting means for detecting the beam current of each of the reference signals from the applied signal, first control means for performing contrast control based on the contrast reference signal of the detecting means, and brightness based on the brightness reference signal of the detecting means. A video signal processing device comprising second control means for controlling. 8. The video signal processing apparatus according to claim 7, wherein the superimposing means superimposes the brightness reference signal during the vertical blanking period of the input video signal. 9. The video signal processing apparatus according to claim 7, wherein the second control means controls the DC potential of the applied signal applied to each electrode. 10. A frequency separating means for separating an input video signal into a low frequency component and a high frequency component, a low frequency component from the frequency separating means to a cathode electrode of a cathode ray tube, and a high frequency component to a grid electrode of the cathode ray tube. A cathode ray tube drive device having an applying means for applying to the cathode. 11. A frequency detecting means for detecting a scanning frequency of an input signal, a control means for controlling an amplitude and a frequency component of an input video signal by a detection signal from the frequency detecting means, and a signal from the controlling means for a cathode ray. A cathode ray tube driving device comprising an applying means for applying to a cathode and a grid electrode of the tube. 12. The cathode ray tube driving device according to claim 11, wherein the control means drives the cathode ray tube by applying a video signal to the cathode electrode at a low scanning frequency and to the cathode and the grid electrode at a high scanning frequency. . 13. The cathode ray tube driving device according to claim 11, wherein the control means controls the amplitude ratio applied to the cathode and the grid electrode. 14. The control means controls the separation of frequency components so that the low frequency component of the input video signal is applied to the cathode electrode and the high frequency component is applied to the grid electrode. The cathode ray tube driving device described.