JP3088321U - Television device and beam current control device - Google Patents

Abstract

(57) [Problem] There is a problem that an effective high-voltage discharge cannot be performed by a beam current control circuit that limits the output of a beam current. SOLUTION: In the beam current control circuit of the chroma IC,
Based on the input of the auto-contrast limiter terminal, when executing the auto-contrast limiter control processing for amplifying, limiting, and releasing the limit of the beam current, connect the spot killer terminal of the microcomputer to this auto-contrast limiter terminal. By inputting an output voltage of 5 V from the spot killer terminal to the auto-contrast limiter terminal, the restriction by the upper limit of the beam current is released in the auto-contrast limiter control processing. This makes it possible to increase the beam current to the upper limit or more when the power is off, and to effectively discharge the high voltage generated between the CRT and the cathode amplifier.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a television device and a beam current control device, and more particularly to a television device and a beam current control device for discharging a high voltage generated on a CRT when a power supply is turned off.

[0002]

[Prior art]

 Conventionally, as this type of television device, a television device disclosed in Japanese Patent Application Laid-Open No. 7-212679 is known. In this publication, a power-off detection unit detects that a power supply of a circuit device that outputs to CRT is turned off, and outputs a power-off detection signal. Then, based on the power-off detection signal, the brightness of the CRT image is increased by the brightness increasing means at the time of power-off. As a result, the high voltage applied between the CRT and the cathode after the power is turned off is quickly discharged, and the phenomenon of remaining spot light emission is prevented. Further, as similar techniques, those disclosed in Japanese Patent Application Laid-Open Nos. 6-4032 and 9-74495 are known.

[0003]

[Problems to be solved by the invention]

 In the above-described conventional television device, a predetermined limit value is provided for the luminance of an image to be increased by the luminance increasing means by a beam current control circuit for limiting the output of a beam current. Therefore, even if the luminance is increased when the power is turned off, there is a problem that the limit value is reached and the high-voltage discharge cannot be performed effectively. Other publications disclose a technique for effectively discharging a high voltage by performing contrast adjustment for making the screen all white. However, even if contrast control is performed, there is a beam current control circuit that controls the output of the beam current, so that the contrast cannot be adjusted beyond the limit value of the beam current control circuit. It is not possible to solve the problem that the limit value of the control circuit reaches a plateau.

The present invention has been made in view of the above-mentioned problem, and it is possible to speed up the discharge of a high voltage applied between a CRT and a cathode by releasing a limitation of a beam current when a power supply is turned off. It aims to provide a possible television device and beam current control device.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the invention according to claim 1 includes a beam current control terminal for inputting a control voltage obtained by appropriately dividing an output voltage of the FBT, and a control voltage input to the beam current control terminal. Has a beam current control circuit for limiting the output of the beam current to the connected CRT when the voltage is less than a predetermined voltage value, and canceling the restriction when the control voltage is higher than the predetermined voltage value. In a television device having a built-in chroma IC, the chroma IC connects the beam current control circuit and the beam current control terminal and detects a power-off operation of shutting off the power supplied to the CRT. An off-operation detection circuit and the power-off operation detection circuit are connected to the power-off operation detection circuit, and the power-off operation can be detected. Connected to the terminal and outputs a predetermined voltage from the spot killer terminal when the power-off operation is detected, thereby changing the voltage value of the control voltage input to the beam current control terminal to the predetermined voltage value. It is configured to include a microcomputer for controlling as described above.

In a television apparatus, a high voltage generated between a CRT and a cathode amplifier is discharged by outputting a large amount of beam current when the power is turned off. Conventionally, a control voltage obtained by appropriately dividing the output voltage of the FBT is input to a beam current control terminal of a beam current control circuit provided in a chroma IC, and when the control voltage is less than a predetermined voltage value (CRT). If the contrast is controlled to be brighter, the output of the beam current is limited. On the other hand, when the control voltage is equal to or higher than the predetermined voltage value (when the contrast of the CRT is controlled to be dark), the limitation of the beam current has been released. That is, when the power is turned off, the contrast is controlled to be bright in order to discharge the high voltage of the CRT. In this case, the control voltage based on the output voltage of the FBT becomes less than a predetermined voltage value. Therefore, the output of the beam current output to the CRT in the beam current control circuit is limited, and the high piezoelectric pressure generated between the CRT and the cathode amplifier cannot be effectively discharged.

Therefore, in the invention according to claim 1 configured as described above, the power-off operation detecting circuit detects the power-off operation of shutting off the power supplied to the CRT. Then, the microcomputer and this power-off operation detection circuit are connected, and the microcomputer can detect the power-off operation. In addition, the spot killer terminal of this microcomputer is connected to the beam current control terminal, and when the microcomputer detects a power-off operation, a predetermined voltage is output from this spot killer terminal. Thus, the voltage value input to the beam current control terminal is controlled to be equal to or higher than the predetermined voltage value. Then, the limitation of the beam current control circuit can be released, and the high voltage generated between the CRT and the cathode amplifier can be effectively discharged when the power is turned off.

With the above-described configuration, the television apparatus as a specific device configuration capable of effectively discharging the high voltage generated in the CRT by releasing the restriction of the beam current control circuit when the power is turned off. Can be provided. On the other hand, such a technical idea is not limited to a specific device (television device) to which the technology is applied, but is also established as a beam current control device capable of releasing a limitation of a beam current to a CRT at a predetermined time. It goes without saying that it can be done.

Therefore, the invention according to claim 2 provides a beam current output means for outputting a beam current to a connected CRT, and an output of the beam current to the CRT by the beam current output means at a predetermined upper limit. Beam current limiting means for limiting, release instruction receiving means for receiving a release instruction for instructing release of the restriction by the beam current limiting means, and beam current when the release instruction is received by the release instruction receiving means. A beam current limit canceling means for canceling the limitation of the upper limit by the limiting means is provided. In the invention according to claim 2 configured as described above, the beam current is output to the connected CRT by the beam current output means. At this time, in the beam current limiting means, when the output of the beam current to the CRT by the beam current output means reaches a predetermined upper limit, the output is limited. Here, in the present invention, when the cancellation instruction is received by the cancellation instruction receiving means, the beam current limitation cancellation means cancels the limitation of the upper limit by the above-described beam current limitation means. As a result, the restriction on the upper limit can be released by appropriately accepting the release instruction at a desired timing.

[0010] As an example of the release instruction received by the release instruction receiving means, the invention according to claim 3 detects the interruption of the power supplied to the CRT in the beam current control device according to claim 2. It has a power cutoff detecting means, and the release instruction receiving means is configured to receive the release instruction when the power cutoff is detected by the power cutoff detecting means. In the invention according to claim 3 configured as described above, the interruption of the power supplied to the CRT is detected by the power interruption detecting means. The release instruction receiving means receives the release instruction when the power cutoff is detected by the power cutoff detection means, and the beam current limit release means releases the upper limit of the beam current. Thus, by releasing the limitation of the beam current when the power is turned off, it becomes possible to effectively discharge the high voltage generated on the CRT when the power is turned off.

It is preferable that the upper limit of the beam current can be explicitly released at a desired timing. Therefore, a device according to a fourth aspect of the present invention is the beam current control device according to the second aspect, wherein the release instruction receiving means has switch means for instructing release of the restriction. When the cancellation instruction is given by the user, the above cancellation instruction is received. In the invention according to claim 4 configured as described above, the release instruction can be executed by the switch means, and the release instruction receiving means receives this release instruction. Then, the beam current restriction canceling means cancels the limitation on the upper limit of the beam current. In this way, by giving the release instruction by the switch means, it is possible to release the upper limit of the beam current at a desired timing.

As a specific method for limiting and canceling the beam current, the invention according to claim 5 is based on the beam current control device according to any one of claims 2 to 4. The beam current limiting means has voltage input means for inputting an output voltage of the FBT, and when the output voltage input from the FBT is equal to or higher than a predetermined voltage value, the restriction can be canceled and the beam current limiting means can be released. The canceling means has a voltage supply means for supplying a voltage to the voltage input means, and the voltage supply means supplies a voltage at which the voltage input by the voltage input means is equal to or higher than a predetermined voltage value to supply the voltage. It is designed to remove the upper limit. In the invention according to claim 5 configured as described above, the beam current limiting means inputs the output voltage of the FBT by the voltage input means, and restricts the output voltage when the output voltage input from the FBT is equal to or higher than a predetermined voltage value. To release. Then, the beam current limit release means supplies a voltage at which the voltage input by the voltage input means becomes equal to or higher than a predetermined voltage value by a voltage supply means for supplying a voltage to the voltage input means when releasing the restriction of the upper limit value. I do.

It is preferable to set an interval for canceling the restriction on the upper limit of the beam current, since the restriction on the beam current can be canceled at a desired interval. According to a sixth aspect of the present invention, in the beam current control device according to any one of the second to fifth aspects, the beam current limit canceling means cancels the limitation of the upper limit. The configuration includes a release interval setting unit that sets an interval. In the invention according to claim 6 configured as described above, an interval for canceling the upper limit is set by the cancel interval setting means. Then, the beam current limit canceling means cancels the limitation of the upper limit at the set interval.

[0014]

[Effect of the invention]

 As described above, the present invention releases the limitation of the beam current control circuit by controlling the voltage value input to the beam current control terminal at the time of power-off to be equal to or higher than the predetermined voltage value, and effectively releases the CRT. A television device capable of discharging a high voltage can be provided. Further, according to the invention of claim 2, it is possible to provide a beam current control device capable of canceling the restriction on the upper limit of the beam current by appropriately accepting a cancellation instruction at a desired timing. Will be possible.

Further, according to the present invention, by removing the limitation of the beam current when the power is turned off, it becomes possible to effectively discharge the high voltage generated in the CRT when the power is turned off. . Further, according to the invention of claim 4, it is possible to release the limitation of the upper limit value of the beam current at a desired timing by giving a release instruction by the switch means. Further, according to the invention of claim 5, a specific method for limiting and canceling the beam current can be presented. Further, according to the invention of claim 6, it is possible to set a time interval for releasing the restriction on the upper limit value of the beam current.

[0016]

[Embodiment of the invention]

 Here, embodiments of the present invention will be described in the following order. (1) Configuration of Television Device: (2) Configuration of Chroma IC: (3) Connection of Chroma IC to FBT and Microcomputer: (4) Signal Timing: (5) Processing Contents of Control Process at Power Off: (6) ) Automatic contrast limiter control processing contents: (7) Summary:

(1) Configuration of Television: FIG. 1 is a configuration diagram showing a configuration of a television device according to the present invention. In FIG. 1, the television apparatus 100 includes a microcomputer 10, and a tuner IC 20, a chroma IC 30, an EEPROM 40, an operation panel 50, and a remote controller (not shown) are directly connected to the microcomputer 10. The antenna 21 and the chroma IC 30 are connected to the tuner IC 20. An audio amplifier 63 and a deflection circuit 65 are connected to the chroma IC 30, and a cathode amplifier 61 is connected via an on-screen display (OSD) circuit 15 in the microcomputer 10. The picture tube (CRT) 62 has a deflection coil 66 attached thereto and is connected to the cathode amplifier 61 and the flyback transformer (FBT) 67 so that a screen can be displayed. Further, the speaker 64 is connected to the audio amplifier 63 and can output sound. The microcomputer 10 controls the entire television apparatus 100 to realize a function as a television.

Here, the tuner IC 20 is a so-called frequency synthesizer type tuner, and includes therein a high-frequency amplifier circuit, a local oscillator circuit, a mixing circuit, and the like (not shown). Of course, the use of the tuner by the frequency synthesizer method is only an example, and for example, the tuner may be a voltage synthesizer method. The high-frequency amplifier circuit has a band-pass filter, and receives a broadcast wave corresponding to a desired frequency from the antenna 21 via the band-pass filter under the control of the microcomputer 10 and amplifies the high-frequency signal. Generate. The frequency of this high-frequency signal is the same frequency as the broadcast radio wave of the selected broadcast. The high-frequency amplifier circuit outputs the generated high-frequency signal to the mixing circuit.

The local oscillation circuit is constituted by a PLL (Phase Locked Loop) circuit, and the PLL circuit generates a local oscillation signal having a local oscillation frequency corresponding to a desired frequency of a broadcast wave and outputs the signal to the mixing circuit. . The mixing circuit mixes the output from the high-frequency amplifier circuit and the local oscillation signal from the local oscillation circuit, converts the mixed signal into an intermediate frequency signal (IF), and outputs it to the chroma IC 30. At this time, the intermediate frequency signal may be output to the chroma IC after passing through the SAW filter. As the high-frequency amplifier circuit, the local oscillation circuit, and the mixing circuit, various television circuits conventionally used can be applied.

(2) Configuration of Chroma IC: Next, the configuration of the above-described chroma IC 30 is shown in the configuration diagram of FIG. In the figure, a chroma IC 30 includes an intermediate frequency amplification (VIF) circuit 31 connected to the tuner IC 20, a VCO (Voltage Controlled Oscillator) circuit 32 connected to the microcomputer 10 and a crystal oscillation circuit (not shown), and a VCO circuit 32. A detection circuit 33 connected to the VIF circuit 31, a synchronization circuit 34 connected to the detection circuit 33, a video signal amplification circuit 35 connected to the detection circuit 33, and a connection to the microcomputer 10 and the video signal amplification circuit 35 The beam current control circuit 36 is provided. As the VIF circuit 31, the VCO circuit 32, the detection circuit 33, the synchronizing circuit 34, and the video signal amplifying circuit 35, various conventionally used circuits for television can be applied.

The VIF circuit 31 amplifies the intermediate frequency signal output from the tuner IC 20 by an intermediate frequency, and outputs the amplified signal to the detection circuit 33. The VCO circuit 32 oscillates an oscillation signal based on a reference oscillation signal input from a crystal oscillation circuit, and can change the oscillation frequency of the oscillation signal according to the input voltage. Here, the microcomputer 10 controls the voltage input to the VCO circuit 32 so that the oscillation frequency becomes corresponding to the type of the received broadcast radio wave. The detection circuit 33 detects the intermediate frequency signal amplified by the VIF circuit 31 based on the oscillation frequency of the oscillation signal, and outputs a video signal and an audio signal. More specifically, the detection circuit 33 performs video detection while synchronizing with the oscillation frequency of the oscillation signal from the intermediate frequency signal amplified by the intermediate frequency, performs predetermined color demodulation processing, separates the video signal, and outputs the separated video signal to the outside. Output.

The video signal amplifying circuit 35 amplifies a luminance signal of the video signal obtained by the detection circuit 33 to a size necessary for operating the picture tube 62. The video signal amplifying circuit 35 amplifies the video signal and adds the video signal to the cathode amplifier 61, and at the same time, distributes the video signal to the sync separation and band amplification. As for the audio signal, a second audio intermediate frequency signal is generated by mixing the audio component and the oscillating signal in the intermediate frequency signal that has been amplified by the intermediate frequency, is subjected to FM detection, is converted into an audio signal, and is output to the outside. . Further, the detection circuit 33 also generates a horizontal / vertical synchronization signal (SYNC) based on the oscillation frequency of the oscillation signal during the detection process and outputs the signal to the synchronization circuit 34. The synchronization circuit 34 generates a sawtooth-shaped horizontal / vertical drive signal based on the input horizontal / vertical synchronization signal, and outputs the signal to a deflection circuit 65 including a horizontal deflection circuit and a vertical deflection circuit.

The video signal output from the video signal amplifier circuit 35 is output to a cathode amplifier 61 via the OSD circuit 15, amplified by the cathode amplifier 61, and supplied to the picture tube 62. Then, the picture tube 62 displays a screen based on the amplified video signal. On the other hand, the audio signal is output to the audio amplifier 63, amplified by the audio amplifier 63, and supplied to the speaker 64. Then, the speaker 64 outputs sound based on the amplified sound signal.

The deflection circuit 65 generates a beam current that draws a locus corresponding to the horizontal / vertical drive signal, and supplies the beam current to a deflection coil 66 attached to the picture tube 62. The deflection coil 66 drives the electron beam based on the beam current in the horizontal and vertical directions of the picture tube 62. The high-frequency signal generated by the deflection circuit 65 is supplied to the FBT 67 so that a high voltage to be supplied to the picture tube 62 is generated. As a result, the electron beam corresponding to the video signal is emitted while being driven in the picture tube 62, and an image appears on the surface of the picture tube 62.

The above-described video signal amplifying circuit 35 outputs the beam current supplied from the deflection circuit 65 to the deflection coil 66 and driven to the picture tube 62 when the video signal is applied to the cathode amplifier 61. Specify the strength. This output intensity is controlled by the beam current control circuit 36. In such a case, the beam current control circuit 36 is connected to the microcomputer 10 and the FBT 67, and controls the degree of output intensity of the beam current based on the control signal of the microcomputer 10 or the appropriately divided output voltage of the FBT 67. At this time, when the output voltage of the FBT 67 is decreasing (when the contrast is bright), the beam current control circuit 36 executes control to reduce the beam current, and when the output voltage of the FBT 67 is increasing (when the contrast is high). In the dark case), the control to reduce the beam current is not executed.

As described above, when the output voltage of the FBT 67 is lowered (when the contrast is bright), when the control for reducing the beam current is executed, if the output voltage of the FBT 67 becomes equal to or lower than a predetermined threshold, the setting is performed. The increase of the beam current output is limited by a predetermined upper limit value. On the other hand, the beam current control circuit 36 in the present embodiment, when the power is turned off and the contrast is adjusted to white by the OSD circuit 15, according to the state of the control signal output from the microcomputer 10, Release the upper limit of the current. As a result, the high voltage generated between the CRT 62 and the cathode amplifier 61 when the power is turned off can be effectively discharged. In the present embodiment, the control for executing the amplification, limitation, and cancellation of the limitation of the beam current executed by the beam current control circuit 36 is referred to as an auto-contrast limiter control process.

The EEPROM 40 is a readable / writable nonvolatile memory of 1 kbit, that is, 128 bytes. In the EEPROM 40, in addition to channel preset data for the tuner IC 20, image quality data such as contrast and brightness, destination data such as for the United States or Japan, and whether the audio output is stereo or not is determined. A plurality of setting data required for the above control, such as data to be executed and data for determining a model, are stored. Here, the microcomputer 10 includes a CPU 11, a ROM 12, a RAM 13, an I / O port 14, an OSD circuit 15, an A / D port 16, a timer circuit (not shown), and the like. The tuner IC 20, the chroma IC 30, the operation panel 50, and the remote controller are connected to the I / O port 14. As described above, the chroma IC 30 and the cathode amplifier 61 are connected to the OSD circuit 15. Then, the CPU 11 executes a predetermined control program stored in the ROM 12 to control the entire television apparatus 100.

(3) Connection Between Chroma IC, FBT, and Microcomputer: FIG. 3 is a connection configuration diagram showing a connection configuration between the chroma IC 30, the FBT 67, and the microcomputer 10. In the figure, the microcomputer 10 can receive a power-off operation from the operation panel 50. The microcomputer 10 and the chroma IC 30 are connected to the spot killer terminal 16 and the auto contrast limiter terminal 37 via the resistor R1 and the diode D1. The output voltage of the FBT 67 is appropriately divided by the resistor R2 and the capacitor C1 and input to the auto contrast limiter terminal 37 from the output terminal 67a. In such a configuration, the beam current control circuit 36 monitors the input voltage input from the auto-contrast limiter terminal 37, and executes the above-described auto-contrast limiter control processing based on the input voltage, thereby amplifying the video signal. The output degree of the beam current when the video signal is output from the circuit 35 is defined.

(4) Timing of Each Signal: FIG. 4 is a signal timing chart showing the timing of each signal in the present embodiment. In the figure, when a power-off operation is performed on the operation panel 50, a power-off signal is turned on and is input to the microcomputer 10. When the power-off signal is turned on, the microcomputer 10 changes the output voltage level of the spot killer terminal 16 from 0 V to 5 V for the timer time T, thereby turning on the control signal for the timer time T. This causes the control signal to be input to the auto-contrast limiter terminal 37 to execute the power-off control process for activating the auto-contrast limiter control process described above.

Then, the input voltage of the auto-contrast limiter terminal 37 is raised from the input voltage level V1 when the normal output voltage of the FBT 67 is input to the input voltage level V2. Here, when the threshold voltage level of the output voltage of the FBT 67 at the time of executing the above-described beam current limitation is set to V3, the control signal output from the spot killer terminal 16 of the microcomputer 10 causes an automatic By lifting the voltage of the contrast limiter terminal 37 to the high side, the upper limit value of the beam current is released in the auto-contrast limiter control processing executed by the beam current control circuit 36. As described above, by releasing the limitation of the beam current when the power is turned off, it becomes possible to effectively discharge the high voltage generated between the CRT 62 and the cathode amplifier 61.

(5) Processing Details of Power-Off Control Processing FIG. 5 is a flowchart showing the processing contents of the power-off control processing executed by the microcomputer 10 described above. In the figure, first, a power-off signal is input from the operation panel 50 (step S100), and it is determined whether or not the input power-off signal is on (step S105). If it is determined that the power-off signal is in the on-state, it is detected that the user has turned off the power of the television apparatus 100, and the output voltage of the spot killer terminal 16 is changed from 0V to 5V, so that the automatic operation is performed. A control signal formed at 5 V is output to the contrast limiter terminal 37 (step S110). Then, the control signal is changed from 0V to 5V during the timer time T (step S115), and after the timer time T elapses, the output voltage of the spot killer terminal 16 is changed from 5V to 0V (step S120). .

As a result, it is possible to cause the beam current control circuit 36 to release the upper limit value of the beam current during the timer time T. The timer time T may be a predetermined fixed value stored in the ROM 12 in advance, or may be set by the user on the OSD screen as appropriate and stored in the RAM 13. On the other hand, if it is determined in step S105 that the power-off signal is off, the output voltage of the spot killer terminal 16 is maintained at 0 V, and the beam current control circuit 36 releases the beam current limitation. It is not executed (step S125).

(6) Processing Contents of Auto-Contrast Limiter Control Processing: FIG. 6 is a flowchart showing processing contents of the auto-contrast limiter control processing executed by the above-described beam current control circuit 36. In the figure, first, the input voltage of the auto-contrast limiter terminal 37 is input (step S200). Then, it is determined whether or not the input voltage is equal to or higher than a predetermined threshold (Step S205). If it is determined that the input voltage is equal to or higher than the predetermined threshold, the upper limit of the beam current is released (step S210), and the beam current corresponding to the input voltage is output. (Step S215). On the other hand, if it is determined in step S205 that the input voltage is lower than the predetermined threshold, the upper limit of the beam current is set, and the output of the beam current is limited based on the upper limit (step S220). ).

(7) Conclusion: As described above, the beam current control circuit 36 of the chroma IC 30 performs the auto-contrast limiter control process for amplifying, limiting, and releasing the limit based on the input of the auto-contrast limiter terminal 37. In executing the above, the spot killer terminal 16 of the microcomputer 10 is connected to the auto-contrast limiter terminal 37, and when the power is turned off, the output voltage of 5V is input to the auto-contrast limiter terminal 37 from the spot killer terminal 16, thereby The restriction by the upper limit of the beam current is canceled by the auto-contrast limiter control processing. This makes it possible to increase the beam current to the upper limit or more when the power is turned off, and to effectively discharge the high voltage generated between the CRT 62 and the cathode amplifier 61.

[Brief description of the drawings]

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

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

FIG. 3 is a connection diagram showing a connection between a chroma IC, an FBT, and a microcomputer.

FIG. 4 is a signal timing chart showing signal timings.

FIG. 5 is a flowchart showing the contents of a power-off control process executed by the microcomputer when the power is turned off.

FIG. 6 is a flowchart showing the details of an auto-contrast limiter control process executed by a beam current control circuit.

[Explanation of symbols]

 DESCRIPTION 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 36 Beam current control circuit 40 EEPROM 50 Operation panel 61 Cathode amplifier 62 Picture tube 63 Audio amplifier 64 Speaker 65 Deflection circuit 66 Deflection coil 67 FBT

Claims (6)

[Utility model registration claims] 1. A beam current control terminal for inputting a control voltage obtained by appropriately dividing an output voltage of an FBT is provided. If the control voltage input to the beam current control terminal is less than a predetermined voltage value, a connection is made. In a television apparatus having a built-in chroma IC having a beam current control circuit for canceling the restriction when the control voltage is equal to or higher than a predetermined voltage value while limiting the output of the beam current to the CRT, A power-off operation detecting circuit for detecting a power-off operation for shutting off power supplied to the CRT while connecting the beam current control circuit to the beam current control terminal at The power-off operation can be detected, and the disposed spot killer terminal is connected to the beam current control terminal and the power-off operation is performed. A microcomputer that controls a voltage value of a control voltage input to the beam current control terminal to be equal to or higher than the predetermined voltage value by outputting a predetermined voltage from the spot killer terminal when an operation is detected. A television device characterized by the above-mentioned. 2. A beam current output means for outputting a beam current to a connected CRT, a beam current limiting means for limiting the output of the beam current to the CRT by the beam current output means at a predetermined upper limit, Release instruction receiving means for receiving a release instruction for instructing release of the restriction by the beam current restriction means, and when the release instruction is received by the release instruction reception means, release of the upper limit value restriction by the beam current restriction means A beam current control device comprising: a beam current limit canceling means. 3. A power cutoff detecting means for detecting a cutoff of power supplied to the CRT, wherein the release instruction receiving means detects the power cutoff by the power cutoff detecting means. 3. The beam current control device according to claim 2, wherein a cancellation instruction is received. 4. The cancellation instruction receiving means has switch means for instructing cancellation of the restriction, and accepts the cancellation instruction when the cancellation instruction is issued by the switch means. Item 3. A beam current control device according to item 2. 5. The beam current limiting means has voltage input means for inputting an output voltage of an FBT. When the output voltage input from the FBT is equal to or higher than a predetermined voltage value, the beam current limiting means can release the restriction. The beam current limit canceling means has a voltage supply means for supplying a voltage to the voltage input means, and supplies a voltage at which the voltage input to the voltage input means is equal to or higher than a predetermined voltage value by the voltage supply means. 5. The beam current control device according to claim 2, wherein the restriction on the upper limit value is released by performing the operation. 6. 6. The apparatus according to claim 2, wherein said beam current limit canceling means has canceling interval setting means for setting an interval for canceling said upper limit. Beam current control device.