JP3094647U - Television and spot killer devices - Google Patents

Abstract

(57) [Problem] To provide a spot killer circuit by setting the first grid of a CRT to a negative voltage when a fluctuation or the like occurs in a DC voltage at the time of power-off or power-on. However, this method has a problem that a high voltage remaining on a CRT cannot be originally removed. SOLUTION: A first spot killer circuit 61a capable of holding a first grid terminal G1 of a CRT 62 at a negative voltage to prevent generation of a spot, and a second spot killer circuit 61a capable of preventing generation of a spot and discharging a high voltage by a normal method. By switching between the spot killer circuit 61c and the switching circuit 61b, the second spot killer circuit 61c is activated when the power is turned off by the operation panel 50 or the like, and the first spot killer circuit 61a is activated in the event of an abnormality. It becomes possible to do.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

  The present invention relates to television and spot killer devices.

[0002]

[Prior art]

  Conventionally, an electron beam is emitted from the cathode of a CRT and the screen on the anode side In the case of a display device that displays on the screen, the moment the power switch is turned off, The capacitor is charged when the power is turned on as a means to prevent spot burns on the CRT. By using the electric charge accumulated by doing so, when the power is turned off, the first grid of the CRT is negatively charged. Position, the electron beam emitted from the cathode of the CRT is suppressed. There is a pot killer circuit. Also, there is a known spot killer circuit of this kind. (For example, refer to Patent Document 1).

[0003]

[Patent Document 1]           JP-A-9-98304

[0004]

[Problems to be solved by the device]

  In the conventional spot killer circuit described above, the power is turned off or turned on. If ripples etc. occur in the DC voltage at the time, negatively charge the first grid of the CRT. A spot killer circuit was realized by applying pressure. But with this technique Has the problem that the high voltage that originally remains in the CRT cannot be removed. It was

[0005]   The present invention has been made in consideration of the above problems, and switches between abnormal time and normal time. If possible, the spot key can be removed while removing the high voltage remaining in the CRT during normal operation. To provide a television and spot killer device that can realize Target

[0006]

[Means for Solving the Problems]

  In order to achieve the above object, a device according to claim 1 is a CRT table when power is cut off. A television that prevents high-intensity spots from appearing in the approximate center of the display screen. The operation panel or remote controller that can be turned off and the power off The supply of high voltage DC voltage to the CRT is cut off regardless of the operation of When the power is cut off further, the first grid terminal of the CRT is held at a negative voltage, The electron beam irradiated on the screen from the cathode of the CRT is suppressed to suppress the above-mentioned scan. The first spot killer circuit that can prevent the generation of pots and the cathode of the CRT By inputting the video signal formed by the peak current to the CRT, The display screen is formed with high brightness, and the high voltage of the CRT is discharged so that the spot Second spot killer circuit that can prevent the occurrence of Output the spot killer control signal when the power is turned off. When a microcomputer that outputs a spot killer control signal output from the above microcomputer is input And switching the first spot killer circuit to the inoperable state, And a switching circuit for switching the two-spot killer circuit to an operable state. I am doing it.

[0007]   In a television, when the power is cut off, a high-brightness screen is displayed at approximately the center of the display screen of the CRT. There are various methods that can be applied to prevent the occurrence of a pot. For example, C Hold the first grid terminal of RT at a negative voltage or peak current at the cathode of CRT. The method of applying can be considered. Conventionally, one of the methods has been adopted to I had it functioning. However, a method of holding the first grid terminal at a negative voltage is adopted. If used, it is impossible to avoid the high voltage remaining on the CRT. In addition, Spots can be prevented by applying a peak current to the sword. In addition, the above high voltage can be removed, but if the AC outlet is accidentally disconnected If it is impossible to control with a microcomputer, etc. I can't take measures.

[0008]   Therefore, in the invention according to claim 1 configured as described above, in the operation panel Or when the power is cut off without depending on the power off operation performed from the remote control. If this happens, the first grid terminal of the CRT can be held at a negative voltage to prevent spots from occurring. The first spot killer circuit and the peak current for the cathode of the CRT The second spot key that can prevent spots from being generated by inputting a video signal Error circuit. Then use the operation panel or remote control to turn off the power. When a work is done, a spot killer control signal is sent from the microcomputer to notify that effect. Output to the switching circuit. Here, the switching circuit inputs the spot killer control signal. If this happens, switch the first spot killer circuit to the inoperable state and Switch the two-spot killer circuit to the ready state. That is, control of the microcomputer Under normal conditions, when a normal power-off operation is performed, prevention of spot generation and high voltage By applying a method that can be removed, microcomputer control is performed like power cutoff that does not depend on power off. If it is impossible, hold the first grid terminal of the CRT at a negative voltage to generate spots. Prevent. As described above, in the present invention, the switching circuit uses the first spot killer circuit and the switching circuit. And the second spot killer circuit to switch the power off. It is possible to perform the spot killer treatment corresponding to.

[0009]   In this way, the procedure for switching the spot killer treatment according to the mode of power interruption The method is not limited to the configuration embodied in the television described above, and realizes this method. It goes without saying that the invention can be realized as a spot killer device.   Therefore, the invention according to claim 2 is the first of the CRT when the power supply is cut off. From the first spot killer circuit that can hold the grid terminal to a negative voltage and the chroma IC The video signal formed by the input peak current can be applied to the cathode of the CRT. The second spot killer circuit and power off operation from the operation panel or remote control A control circuit that outputs a control signal when it is detected and a control circuit that is output from the control circuit. When the control signal is input, the first spot killer circuit is switched to the inoperable state. The second spot killer circuit is switched to the operable state, and the control signal If you don't input, switch the first spot killer circuit to the operable state. And a switching circuit for switching the second spot killer circuit to the inoperable state. It is provided as a configuration.   In the invention according to claim 2 configured as described above, the power supply is cut off. If the CRT's first grid terminal is held at a negative voltage, the first spot killer circuit And the video signal formed by the peak current input from the chroma IC to the CRT. And a second spot killer circuit that can be applied to the cathode of the. And The control circuit controls when the power off operation from the operation panel or remote control is detected. A control signal is output, and at this time, the switching circuit disables the first spot killer circuit. The second spot killer circuit is switched to the operable state as well as being switched to the active state. On the other hand, the switching circuit creates the first spot killer circuit when no control signal is input. The second spot killer circuit is switched off and the second spot killer circuit is switched off. Change.

[0010]   As an example of a specific configuration of the first spot killer circuit, the invention according to claim 3 is The spot killer device according to claim 2, wherein the first spot killer is provided. The circuit should be connected in series with the capacitor connected from the power supply side. The diode and the anode side of the diode is It is connected to the first grid terminal and the cathode side of the diode is grounded. It is configured to be.   In the invention according to claim 3 configured as described above, the first spot killer is provided. A capacitor connected to the circuit from the power supply side and a capacitor connected in series with the capacitor. Prepare with Iodo. Then, the anode side of the diode is Connect to the first grid terminal and ground the cathode side of the diode. by this When the power supply is cut off at the power supply side, the charge stored in the capacitor is It flows to the pay side. At this time, based on the characteristics of the diode, the voltage of the first grid terminal , It is possible to hold the first grid terminal at a negative voltage. .

[0011]   As an example of a concrete configuration of the switching circuit, the invention according to claim 4 is the above-mentioned claim 1. ~ In the spot killer device according to any one of claims 3 to 4, the switching circuit includes: The collector terminal is connected to the anode side of the diode and the base terminal is the control terminal. It is connected to the control circuit so that signals can be input, and the emitter terminal is grounded. It is configured as a register.   In the invention according to claim 4 configured as described above, the switching circuit includes a transition circuit. It is formed with a star. At this time, connect the collector terminal of the transistor to the diode Connect the base terminal to the control circuit so that the control signal can be input. Ground the terminal. This ensures that when the control signal is input to the base terminal, It becomes possible to turn on the transistor. When the transistor turns on In this case, the diode can be short-circuited and the first grid terminal must be kept at a negative voltage. You can prevent it from being held. That is, the first spot killer circuit is activated It can be disabled.

[0012]   It is preferable to dispose each of the circuits described above on the same substrate because the device can be simplified. Therefore, a device according to claim 5 is the device according to any one of claims 1 to 4. In the spot killer device, the first spot killer circuit and the second spot killer circuit are provided. The Tokiller circuit and the switching circuit are formed on the same substrate.   In the invention according to claim 5 configured as described above, the first spot killer is provided. The circuit, the second spot killer circuit, and the switching circuit are formed on the same substrate.

[0013]

[Effect of device]

  As described above, according to the first aspect of the invention, the switching circuit includes the first By switching between the killer circuit and the second spot killer circuit, A TV that can treat spot killer depending on whether the power is off or not. John can be offered.   According to another aspect of the invention, the switching circuit includes the first spot killer circuit. And by switching the second spot killer circuit, A spot killer device that can treat spot killer according to the presence or absence Can be provided.   Further, according to the invention of claim 3, a first spot killer circuit is realized. An example of a specific configuration can be presented.   Further, according to the invention of claim 4, there is provided a specific configuration for realizing the switching circuit. An example can be presented.   Further, according to the invention of claim 5, it is possible to simplify the circuit configuration. Become.

[0014]

[Embodiment of device]

  Here, an embodiment of the present invention will be described in the following order. (1) Configuration of television device: (2) Structure of chroma IC: (3) Schematic configuration of the cathode amplifier: (4) Detailed configuration of cathode amplifier: (5) Operation contents of spot killer operation: (6) Summary:

[0015]   (1) Configuration of television:   FIG. 1 is a configuration diagram showing a configuration of a television according to the present invention.   In the figure, a television 100 includes a microcomputer 10, and this microcomputer 1 0 includes a tuner IC 20, a chroma IC 30, an EEPROM 40, and an operation pattern. The channel 50 and a remote controller (not shown) are directly connected. And tuner IC An antenna 21 and a chroma IC 30 are connected to 20. Chroma IC3 An audio amplifier 63 and a deflection circuit 65 are connected to Cathode via on-screen display (OSD) circuit 15 in controller 10 The amplifier 61 is connected. The deflection coil 66 is attached to the CRT 62. Also connected to the cathode amplifier 61 and the flyback transformer (FBT) 67. It is possible to display the screen. Also, the speaker 64 is It is connected to the O-amplifier 63 and can output voice.

[0016]   Here, the tuner IC 20 is a so-called frequency synthesizer type tuner. Equipped with a high-frequency amplifier circuit, a local oscillator circuit, a mixing circuit, etc. It Of course, setting the tuner to the frequency synthesizer system is only an example. Alternatively, a voltage synthesizer method may be used. The high frequency amplifier circuit is a band pass filter. This band from the antenna 21 based on the control of the microcomputer 10 Receives radio waves corresponding to the desired frequency through a pass filter, amplifies them, and Generate a signal. The frequency of this high-frequency signal is the same frequency as the broadcast wave of the selected broadcast. The wave number. The high frequency amplifier circuit outputs the generated high frequency signal to the mixing circuit.

[0017]   The local oscillator circuit is a PLL (Phase Locked Loop) circuit. This PLL circuit is used to generate local signals that correspond to the desired frequency of broadcast radio waves. It generates a local oscillation signal of the oscillation frequency and outputs it to the mixing circuit. Mixing circuit increases high frequency Intermediate frequency signal by mixing the output from the width circuit and the local oscillation signal from the local oscillation circuit (IF) and output to the chroma IC 30. At that time, the intermediate frequency signal is SAW It may be passed through a filter and then output to the chroma IC. High-frequency amplifier circuit , Local oscillator circuit, and mixing circuit are used for various televisions that have been conventionally adopted. Circuitry can be applied.

[0018]   Further, the EEPROM 40 directly connected to the microcomputer 10 can read and write. It is a non-volatile memory of 1 kbit, that is, 128 bytes. This EEPROM 40 includes channel preset data for the tuner IC 20 and a controller 40. Image data such as trust and brightness, and destination data such as for the US or Japan Data, the data that determines whether the audio output is stereo, and the model. A plurality of setting data necessary for the above control such as data are stored. Where ma The icon 10 includes a CPU 11, a ROM 12, a RAM 13, and an I / O port 1. 4, an OSD circuit 15, an A / D port 16, an unillustrated timer circuit, etc. Has been done. In addition, the I / O port 14 has a tuner IC 20 and a chroma IC 3 0, operation panel 50, remote controller (not shown), and cathode amplifier 61 are connected Has been done. The OSD circuit 15 includes a chroma IC 30 and a cathode amplifier 6 1 and 1 are connected. Then, the CPU 11 causes a predetermined control stored in the ROM 12 to be performed. By executing the program, the entire television 100 is controlled, The function as a television is realized.

[0019]   (2) Structure of chroma IC:   Next, the configuration of the chroma IC 30 described above is shown in the configuration diagram of FIG. In the figure, The chroma IC 30 is an intermediate frequency amplification (VIF) circuit 3 connected to the tuner IC 20. 1, a VCO (Volta) connected to the microcomputer 10 and a crystal oscillation circuit (not shown). ge Controlled Oscillator) circuit 32 and VCO circuit 3 2 and the detection circuit 33 connected to the VIF circuit 31, and the detection circuit 33 connected to the detection circuit 33. The term circuit 34, the video signal amplifier circuit 35 connected to the detector circuit 33, and the microcomputer 1 0 and a beam current control circuit 36 connected to the video signal amplification circuit 35. There is. The VIF circuit 31, the VCO circuit 32, the detection circuit 33, the synchronization circuit 34, The video signal amplifier circuit 35 is a circuit for various televisions that has been conventionally adopted. Can be applied.

[0020]   The VIF circuit 31 converts the intermediate frequency signal output from the tuner IC 20 into an intermediate frequency signal. The signal is amplified and output to the detection circuit 33. The VCO circuit 32 is input from the crystal oscillator circuit. Oscillates the oscillation signal based on the reference oscillation signal that is Accordingly, it is possible to change the oscillation frequency of the oscillation signal. Here, the microcomputer 10 The VCO frequency so that the oscillating frequency corresponds to the type of broadcast radio wave received. It controls the voltage input to path 32. The detection circuit 33 determines the oscillation frequency of the oscillation signal. Based on the number, the intermediate frequency signal amplified by the intermediate frequency signal in the VIF circuit 31 is detected. It outputs a video signal and an audio signal. More specifically, the detection circuit 33 is Video detection from the amplified intermediate frequency signal in synchronization with the oscillation frequency of the oscillation signal Then, a predetermined color demodulation process is performed and the video signal is separated and output to the outside.

[0021]   The video signal amplification circuit 35 is a luminance signal of the video signals obtained by the detection circuit 33. Is amplified to the size required to operate CRT62. This video signal amplification The circuit 35 amplifies the video signal and adds the video signal to the cathode amplifier 61 at the same time. In addition, it is also distributed for synchronization separation and band amplification. For audio signals, The second audio intermediate by mixing the audio component and the oscillating signal in the wave-amplified intermediate frequency signal A frequency signal is generated and FM detection is performed to generate a voice signal, which is output to the outside. further, The detection circuit 33 detects horizontal / vertical synchronization based on the oscillation frequency of the oscillation signal during the detection process. A signal (SYNC) is also generated and output to the synchronization circuit 34. The synchronization circuit 34 is A sawtooth-shaped horizontal / vertical drive signal is generated based on the horizontal / vertical sync signal. And outputs it to a deflection circuit 65 including a horizontal deflection circuit and a vertical deflection circuit.

[0022]   The video signal output from the video signal amplifier circuit 35 is transmitted through the OSD circuit 15 to the cover. It is output to the sword amplifier 61, amplified by this cathode amplifier 61, and the CRT 6 2 is supplied. Then, the CRT 62 displays the screen based on the amplified video signal. Make an indication. On the other hand, the audio signal is output to the audio amplifier 63 and this audio signal is output. It is amplified by the audio amplifier 63 and supplied to the speaker 64. And the speaker 64 outputs a voice based on the amplified voice signal.

[0023]   The deflection circuit 65 outputs a beam current that draws a locus corresponding to the horizontal and vertical drive signals. It is generated and supplied to the deflection coil 66 attached to the CRT 62. Deflection coil 6 6 is an electron beam based on this beam current that is dried in the horizontal and vertical directions of the CRT 62. To The high frequency signal generated in the deflection circuit 65 is supplied to the FBT 67, A high voltage supplied to the CRT 62 is generated. As a result, CRT6 In 2, the electron beam corresponding to the video signal is emitted while being driven, and the CRT 62 An image will appear on the tube surface of.

[0024]   The video signal amplification circuit 35 described above is used to add the video signal to the cathode amplifier 61. At this time, the deflection circuit 65 supplies the deflection coil 66 to the CRT 62. It defines the output intensity of the driven beam current. This output intensity is controlled by the beam current. It is controlled by the control circuit 36. In such a case, the beam current control circuit 36 is 10 is connected to the controller 10, and the output intensity degree of the beam current is determined based on the control signal of the microcomputer 10. Control. The beam current control circuit 36 in the present embodiment is the operation panel 50. Alternatively, when the power is turned off by operating a remote controller (not shown), the microcomputer 10 A video signal (beam current intensity) whose contrast can be adjusted to white from the OSD circuit 15 Output a video signal composed of the peak current value. Output such a video signal By doing so, the display screen of the CRT 62 becomes high in brightness for a moment after the power-off operation. However, even if the anode voltage drops and horizontal and vertical deflection stop, a spot appears on the display screen. It becomes possible not to give birth. That is, according to this method, the power is turned off. Occasionally the spot is prevented from occurring and the CRT 62 and the cathode amplifier 61 are The high voltage generated between them can be effectively discharged.

[0025]   On the other hand, the operation when the power is turned off is the same as the operation panel 50 or the remote It works only when the power is turned off from the computer. Therefore, the AC concentric If there is an abnormality such as chattering in the power supply due to unstable connection of the power supply, , This function will not be executed. Avoiding spots in such situations Can not do it. Therefore, in the present embodiment, the connection state of the AC outlet is In the event of abnormal conditions such as when the power supply is chattering due to unstable conditions, Method to avoid spots, and also during normal operation (operation panel or If the power is turned off by the remote control (not shown), use the method described above. Spots that prevent the occurrence of spots and enable effective discharge of high voltage Propose a killer device.

[0026]   (3) Schematic configuration of the cathode amplifier:   FIG. 3 is a schematic view of a cathode amplifier 61 incorporating the above-mentioned spot killer device. It is a block diagram which showed schematic structure. In addition, here is a spot killer according to the present invention. The structure regarding an apparatus is shown. In the figure, the cathode amplifier 61 is a first switch. Pot killer circuit 61a, switching circuit 61b, second spot killer circuit 61c It consists of and. The first spot killer circuit 61a is the first group of the CRT 62. While being connected to the lid terminal G1, the second spot killer circuit 61c is CR It is connected to the cathode terminals TR, TG and TB of T62. First spot killer circuit The high-voltage power supply is input to the reference numeral 61a. By detecting the abnormal state and holding the first grid terminal G1 at a negative voltage, CR By suppressing the electron beam emitted from the cathode of T62, the spot To prevent the occurrence of.

[0027]   On the other hand, the second spot killer circuit 61c outputs the above-mentioned video signal to the CRT 62. By outputting to the sword terminals TR, TG, TB, it is possible to prevent the occurrence of spots. And discharge the high voltage. Here, the switching circuit 61b is the I / O of the microcomputer 10. It is connected to port 14 and the spot killer control signal can be input from the microcomputer 10. It has become Noh. Then, the spot killer control signal is input from the microcomputer 10. In this case, the second spot killer circuit 61c is switched to the operable state (in this case, , The first spot killer circuit 61a becomes inoperable. ), Spot killer system If the control signal is not input, switch the spot killer circuit 61a to the operable state. (In such a case, the second spot killer circuit 61b becomes inoperable). As a result, the power off operation can be performed from the operation panel 50 or a remote controller (not shown). During normal operation, the second spot killer circuit 61c prevents spots from occurring. And the chattering of the AC outlet occurs and the power is turned off. When an abnormality occurs, the first spot killer circuit 61a operates to prevent spots from occurring. Make it possible to do.

[0028]   (4) Detailed configuration of cathode amplifier:   FIG. 4 is a configuration diagram showing a detailed configuration of the cathode amplifier 61. In addition, here Shows a configuration relating to a spot killer device according to the present invention. In the figure In the first spot killer circuit 61a, the power supply terminal 61a1 is connected to the high voltage power supply. The power of + 180V is supplied from the power supply terminal 61a1. Also, The terminal 61a2 is a ground terminal. A capacitor 61a3 is connected to the power supply terminal 61a1. Is connected to the opposite side of the power supply terminal 61a1 of the capacitor 61a. The cathode terminal of the diode 61a4 is connected. Of the diode 61a4 The anode terminal is grounded.

[0029]   The cathode terminal of the diode 61a4 is the first grid terminal of the CRT 62. It is connected to G1. With this configuration, + 180V is supplied to the power supply terminal 61a1. Then, the capacitor 61a3 is charged with + 180V. And the AC controller When + 180V drops to 0V due to the chattering of cents, etc., the capacitor The electric charge stored in 61a3 flows to the power supply terminal 61a side. At this time, Daio Due to the characteristics of the terminal 61a4, the first grid terminal G1 of the CRT 62 is pulled to a negative voltage. Get caught. Then, due to this drawing, the first grid terminal G1 is -180. Held at V. This suppresses the electron beam output at the CRT 62. This makes it possible to avoid the occurrence of spots.

[0030]   The switching circuit 61b is a spot killer output by the microcomputer 10 at the terminal 61b1. Input the control signal. A transistor is connected to this terminal 61b1 through a resistor 61b2. The base terminal of 61a3 is connected, and the base terminal is grounded through the resistor 61b4. Has been done. The collector terminal of the transistor 61b3 is connected to the first spot killer. Circuit 61a is connected via a resistor 61a5. Therefore, the spot killer When the control signal is input, the transistor 61a3 turns on. Then, the first sports Since the diode 61a4 of the shut killer circuit 61a is short-circuited, The first grid terminal G1 of the CRT 62 is pulled to a negative voltage due to the characteristics of the card 61a4. Disable the movement. That is, the first spot killer circuit 61a is inoperable. State. In this way, if the spot killer control signal is input, Based on the control of 10, the second spot killer circuit 61c performs the normal spotting described above. Do Tokiller action. Here, the first spot killer circuit 61a and the switching circuit By forming 61b and the second spot killer circuit 61c on the same substrate, As a result, the circuit configuration can be simplified.

[0031]   (5) Operation contents of spot killer operation:   FIG. 5 is an operation flowchart showing the processing contents of the normal spot killer operation. Is. In this case, control of the microcomputer 10 is involved. In the figure The microcomputer 10 is powered off by the operation panel 50 or a remote controller (not shown). It is determined whether or not an operation has been performed (step S100). Power off operation was performed If it is determined, the microcomputer 10 controls the spot killer via the I / O port 14. The signal is turned on (step S105). This spot killer control signal is the first It is input to the terminal 61b1 of the spot killer circuit 61a, and the transistor 61b3 Turn on (step S110). This shorts the diode 61a4. Therefore, when the power is turned off, the voltage supplied to the power supply terminal 61a1 changes to 0V. Even if it does, the first grid terminal G1 of CRT62 should not be -180V. (Step S115).

[0032]   Here, the microcomputer 10 controls the beam current control circuit 36 of the chroma IC 30. Then, the video signal based on the above-mentioned peak current value is sent to the second spot killer circuit 61c. Input to the input terminal 61c1. This video signal consists of resistors 61c4, 6, 6 and Cathode terminals TR, TG, T of the CRT 62 via the transistors 61c5, 7, 9 It is input to B (step S120). By inputting this video signal to the CRT 62, Therefore, the above-mentioned normal spots are prevented from occurring and spot burns are prevented. (Step S125), the high voltage is removed (step S125). 130). This video signal is input for a predetermined time (step S135), and at a predetermined time After a while, the power is turned off (step S140).

[0033]   FIG. 6 is an operation flowchart showing the processing contents of the spot killer operation at the time of abnormality. Is. In this case, control of the microcomputer 10 is involved. In the figure If the supply of external commercial power is interrupted due to chattering of the AC outlet, etc. , + 180V of the high voltage power supply supplied to the power supply terminal 61a1 drops to about 0V (Step S200). Then, the electric charge of the capacitor 61a3 changes to the power supply terminal 61a1. Is discharged to the side (step S205). At this time, the spot killer control signal is turned off. Therefore, the transistor 61b3 is turned off and the characteristics of the diode 61a4 are reduced. Based on the above, the first grid terminal G1 of the CRT 62 is pulled to −180V ( Step S210). This suppresses the electron beam emitted to the CRT 62. (Step S215), it is possible to avoid the occurrence of spots and prevent spot burning. (Step S220).

[0034]   (6) Summary:   In this way, the first grid terminal G1 of the CRT 62 is held at a negative voltage and spotted. Spot killer circuit 61a that can prevent the occurrence of The second spot killer circuit 61c capable of preventing the occurrence of a dot and the like in the switching circuit 61b Therefore, when the power is turned off on the operation panel 50 or the like by making it switchable. Activates the second spot killer circuit 61c. It becomes possible to operate the circuit 61a.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a television according to the present invention.

FIG. 2 is a configuration diagram showing a configuration of a chroma IC.

FIG. 3 is a configuration diagram showing a schematic configuration of a spot killer circuit according to the present invention.

FIG. 4 is a configuration diagram showing a detailed configuration of a spot killer circuit according to the present invention.

FIG. 5 is a flowchart showing the operation contents of a spot killer operation during normal operation.

FIG. 6 is a flowchart showing operation contents of a spot killer operation at the time of abnormality.

[Explanation of symbols]

10 ... Microcomputer 11 ... CPU 12 ... ROM 13 ... RAM 14 ... I / O port 15 ... OSD circuit 16 ... A / D port 20 ... Tuner IC 30 ... Chroma IC 31 ... VIF circuit 32 ... VCO circuit 33 ... Detection circuit 34 ... Synchronous circuit 35 ... Video signal amplifier circuit 36 ... Beam current control circuit 40 ... EEPROM 50 ... Operation panel 61 ... Cathode amplifier 62 ... CRT 63 ... Audio amplifier 64 ... speaker 65 ... Deflection circuit 66 ... Deflection coil 67 ... FBT

Claims (5)

[Scope of utility model registration request] 1. A television, which prevents a high-intensity spot from being generated in the approximate center of a display screen of a CRT when the power is shut off, an operation panel or a remote controller capable of performing a power-off operation, and the power-off operation. When the power supply is cut off by cutting off the supply of the high voltage DC voltage to the CRT without depending on the above, the electron is emitted from the cathode of the CRT to the screen by keeping the first grid terminal of the CRT at a negative voltage. By inputting the first spot killer circuit capable of suppressing the beam to prevent the generation of the spot and the video signal formed by the peak current to the cathode of the CRT, the display screen of the CRT has high brightness. And a second spot killer circuit which is formed on the CRT and can discharge the high voltage of the CRT to prevent the generation of the spot. When the power off operation is performed by the panel or the remote control, the microcomputer that outputs the spot killer control signal and the first spot killer circuit that operates when the spot killer control signal output by the microcomputer is input And a switching circuit for switching the second spot killer circuit to an operable state while switching to the disabled state. 2. A first spot killer circuit capable of holding the first grid terminal of the CRT at a negative voltage when the power supply is cut off, and a video signal formed by a peak current input from a chroma IC to the CRT. The second spot killer circuit that can be applied to the cathode of the control circuit, the control circuit that outputs a control signal when a power-off operation from the operation panel or the remote control is detected, and the control signal that is output from the control circuit described above. The first spot killer circuit is switched to the inoperable state, the second spot killer circuit is switched to the operable state, and when the control signal is not input, the first spot killer circuit is switched to the operable state and the second spot A spot killer device comprising a switching circuit for switching the killer circuit to an inoperable state. 3. The first spot killer circuit has a capacitor connected from the power supply side and a diode connected in series to the capacitor, and the anode side of the diode has the capacitor and the first grid. The spot killer device according to claim 2, wherein the diode is connected to a terminal and the cathode side of the diode is grounded. 4. The switching circuit is formed by a transistor whose collector terminal is connected to the anode side of the diode, whose base terminal is connected to the control circuit so that the control signal can be input, and whose emitter terminal is grounded. The spot killer device according to claim 3, wherein the spot killer device is provided. 5. The second to fourth claim, wherein the first spot killer circuit, the second spot killer circuit, and the switching circuit are formed on the same substrate.
The spot killer device according to any one of 1.