JP3551959B2 - Television, video display device, voltage control method of video display device, and method of measuring maximum X-ray radiation amount of video display device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a television, a video display device, a voltage control method for a video display device, and a method for measuring a maximum X-ray radiation amount of a video display device, which include a protection circuit capable of stopping supply of the high voltage to a picture tube.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an image display device such as a television provided with an X-ray protection circuit, the one shown in FIG. 8 is known. In the figure, a video display device includes a power supply circuit 1 that receives an AC voltage and generates a plurality of potential DC reference voltages, a flyback transformer 2 that receives a reference voltage and generates a high-voltage anode voltage, A picture tube 3 for emitting an electron beam toward a predetermined tube surface based on the voltage, and a reference voltage is supplied to the power supply circuit 1 when the reference voltage becomes equal to or higher than a predetermined voltage so as to prevent X-ray emission from the picture tube 3. And a semi-fixed resistor 5 that can change the magnitude of a reference voltage generated by the power supply circuit 1. When the reference voltage becomes equal to or higher than the predetermined voltage, the power is turned off by the X-ray protection circuit 4 and the supply of the anode voltage to the picture tube 3 is stopped. The amount of X-ray radiation from the picture tube increases rapidly as the anode voltage increases. However, by preventing the anode voltage from exceeding a predetermined voltage, it is possible to prevent the X-ray radiation from the picture tube.
Here, at the time of product shipment of the image display device, the maximum amount of X-ray radiation is measured by sampling inspection. At this time, the operator turns the semi-fixed resistor 5 attached to the power supply circuit 1 that generates the reference voltage to raise the reference voltage, and raises the reference voltage to a voltage immediately before the X-ray protection circuit operates. After that, the measuring unit of the X-ray radiation measuring apparatus is brought to the surface of the picture tube to measure the maximum X-ray radiation.
[0003]
[Problems to be solved by the invention]
In the above-described conventional technique, it is troublesome to turn the semi-fixed resistor to raise the reference voltage to a voltage immediately before the X-ray protection circuit operates. In addition, since the power is turned off when the X-ray protection circuit operates, it is necessary to adjust the semi-fixed resistor so as to reduce the reference voltage to a voltage immediately before the X-ray protection circuit operates after the power is turned on. In some cases, the operation of turning on the power and turning the semi-fixed resistor is repeated until the semi-fixed resistor is accurately adjusted.
[0004]
The technique disclosed in Japanese Unexamined Utility Model Publication No. 6-70367 is to start an X-ray protection operation when the divided voltage of the anode voltage becomes equal to or higher than a threshold voltage, and is disclosed in Japanese Unexamined Patent Application Publication No. 7-264511. The technology has been developed to enable adjustment of the circuit group even when the power supply protection function is activated, eliminating the hassle of raising the reference voltage to the voltage immediately before the X-ray protection circuit operates. I can't. The technique disclosed in Japanese Patent Application Laid-Open No. 53-80155 makes it possible to absorb variations in various parts by using a semi-fixed volume. The technique disclosed in Japanese Patent Application Laid-Open No. 58-221573 discloses an image display. In order to guarantee the safety against unnecessary radiation while using an inexpensive circuit when repairing the equipment, it also eliminates the hassle of raising the reference voltage to the voltage just before the X-ray protection circuit operates I can't.
The present invention has been made in view of the above problems, and has a television, a video display device, a voltage control method of a video display device, and a video display device capable of facilitating a task of measuring a maximum X-ray radiation amount. It aims to provide a method for measuring the maximum X-ray radiation.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 receives an AC voltage and generates a high-potential DC reference voltage and a low-potential DC reference voltage which is set to a potential substantially proportional to the high potential. A power supply circuit, a flyback transformer that inputs a reference voltage of the same high potential and generates a high voltage that increases as the reference voltage of the same high potential increases, and an electron beam on a predetermined surface based on the high voltage And a X-ray protector for stopping the generation of the reference voltage by the power supply circuit when the high-potential reference voltage becomes equal to or higher than a predetermined voltage so as to prevent the emission of X-rays from the picture tube. And a power supply circuit, wherein the power supply circuit has a voltage variable circuit capable of changing a magnitude of a reference voltage to be generated. A voltage dividing circuit connected in series with a resistance circuit having a predetermined resistance value, and a voltage dividing circuit interposed between a power supply line of the low potential reference voltage and ground; An A / D converter for inputting the voltage of the intermediate connection part of the circuit and converting it to a digital voltage value, and a RAM for storing the same voltage value, and creating the control voltage for increasing the reference voltage stepwise The digital voltage value is obtained from the A / D converter while increasing the reference voltage by outputting the voltage to the voltage variable circuit and stored in the RAM, and the X-ray protection circuit is controlled based on the voltage value. It is determined whether or not the power supply circuit has stopped the generation of the reference voltage, and when the X-ray protection circuit determines that the generation of the reference voltage has been stopped, the X-ray protection circuit is read from the RAM. The circuit reads a voltage value corresponding to immediately before stopping the generation of the reference voltage, creates the control voltage so that the low-potential reference voltage becomes a voltage corresponding to the voltage value, and outputs the control voltage to the voltage variable circuit. And a microcomputer that performs control for adjusting the reference voltage.
[0006]
That is, the voltage variable circuit can change the magnitude of the reference voltage generated by the power supply circuit based on the input control voltage. The microcomputer generates a control voltage for increasing the reference voltage stepwise and outputs the control voltage to the voltage variable circuit, thereby increasing the reference voltage from the A / D converter and generating a digital voltage corresponding to the divided voltage of the low-potential reference voltage. The voltage value is obtained and stored in the RAM. Further, based on the obtained digital voltage value, it is determined whether or not the X-ray protection circuit has caused the power supply circuit to stop generating the reference voltage. When the X-ray protection circuit determines that the generation of the reference voltage has been stopped, a digital voltage value corresponding to immediately before the X-ray protection circuit stops generation of the reference voltage is read from the RAM. Then, control for adjusting the reference voltage is performed by creating a control voltage so that the low-potential reference voltage becomes a voltage corresponding to the digital voltage value and outputting the control voltage to the voltage variable circuit.
Here, the high-potential reference voltage is a potential substantially proportional to the low-potential reference voltage, and by detecting a divided voltage of the low-potential reference voltage, the X-ray protection circuit immediately before the generation is stopped by the X-ray protection circuit. The reference voltage can be automatically generated by the power supply circuit. Since the high voltage supplied to the picture tube increases as the reference voltage of the high potential increases, the high voltage immediately before the protection circuit stops supplying the picture is supplied to the picture tube based on the case where the high voltage is increased. , The maximum amount of X-ray radiation can be measured. Therefore, the operation of increasing the high voltage supplied to the picture tube up to the voltage immediately before the protection circuit operates does not require any trouble, and the operation of measuring the maximum amount of X-ray radiation can be facilitated.
[0007]
By the way, the present invention can be applied to various video display devices used other than the television. Therefore, the invention according to claim 2 is a video display device comprising a protection circuit for stopping supply of the high voltage to the picture tube when the high voltage supplied to the picture tube becomes equal to or higher than a predetermined voltage. A case where the high voltage is generated by changing the high voltage, a reference voltage detecting unit that detects a DC reference voltage that changes corresponding to the high voltage, and the high voltage generating unit increases the high voltage. As a reference, the protection circuit causes the reference voltage detection means to detect the reference voltage immediately before stopping the supply of the high voltage to the picture tube, and detects the high voltage corresponding to the detected reference voltage immediately before the high voltage. And a voltage control unit that controls the voltage generation unit to generate the voltage.
[0008]
That is, the high voltage generating means generates the high voltage supplied to the picture tube in a changeable manner. The reference voltage detecting means detects a DC reference voltage that changes according to the high voltage. The voltage control means causes the reference voltage detection means to detect a reference voltage immediately before the protection circuit stops supplying the high voltage to the picture tube with reference to a case where the high voltage is increased by the high voltage generation means. Then, control is performed to cause the high voltage generation means to generate a high voltage corresponding to the detected reference voltage immediately before. Then, the high voltage immediately before the protection circuit stops the supply is automatically supplied to the picture tube on the basis of the case where the high voltage is increased, so that the maximum X-ray radiation amount can be measured. Therefore, the operation of increasing the high voltage supplied to the picture tube up to the voltage immediately before the protection circuit operates does not require any trouble, and the operation of measuring the maximum amount of X-ray radiation can be facilitated.
[0009]
Here, as in the invention according to claim 3, the high-voltage generating means has a power supply circuit that receives a primary-side voltage and generates a secondary-side DC reference voltage. The high voltage that generates a high voltage is generated, and the voltage control unit raises the reference voltage to the power supply circuit while increasing the reference voltage to the reference voltage immediately before the protection circuit stops supplying the high voltage to the picture tube. The reference voltage detecting means may detect the reference voltage, and the power supply circuit may generate the reference voltage so that the detected reference voltage becomes the detected reference voltage immediately before. That is, when the reference voltage is increased in the power supply circuit, the high voltage supplied to the picture tube also increases. Therefore, if the power supply circuit generates the reference voltage to be the reference voltage immediately before the supply of the high voltage is stopped, the high voltage immediately before the protection circuit stops the supply can be supplied to the picture tube.
[0010]
Further, as a specific example of the configuration of the voltage control means, the invention according to claim 4 is characterized in that the voltage control means has a storage area for storing a voltage value corresponding to the reference voltage, and the voltage control means is provided in a stepwise manner in the power circuit. The reference voltage is detected by the reference voltage detecting means while increasing the reference voltage, and a voltage value corresponding to the detected reference voltage is obtained and stored in the storage area. It is determined whether or not the supply of the high voltage is stopped, and when the protection circuit determines that the supply of the high voltage is stopped, immediately before the protection circuit stops the supply of the high voltage from the storage area. A corresponding voltage value is read, and the power supply circuit generates the reference voltage so as to be a reference voltage corresponding to the voltage value.
That is, by storing the voltage value corresponding to the detected reference voltage, the reference voltage immediately before the supply of the high voltage is stopped can be easily generated. High voltage can be supplied.
[0011]
Further, as in the invention according to claim 5, the voltage control means generates the reference voltage in the power supply circuit so as to be a reference voltage corresponding to a voltage value immediately before stopping the supply of the high voltage. When this is done, a configuration may be output to the outside that prompts the user to measure the amount of X-ray radiation from the picture tube. That is, when a reference voltage capable of measuring the amount of X-ray radiation is generated, this fact can be known, so that the convenience in measuring the maximum amount of X-ray radiation is improved.
Here, various configurations for outputting the above-mentioned facts are conceivable. For example, the above-mentioned facts may be output by displaying on a picture tube, or the above-mentioned facts may be output by audio output from a speaker.
[0012]
By the way, as an example of a configuration for detecting a reference voltage, the invention according to claim 6 is characterized in that the reference voltage detection means connects a resistance circuit having a predetermined resistance value in series and connects a reference voltage power supply line to a ground. A voltage dividing circuit is provided, and the reference voltage is detected by detecting a voltage at an intermediate connection portion of the voltage dividing circuit. That is, since the voltage dividing circuit divides the reference voltage at the intermediate connecting portion, the reference voltage detecting means can detect the reference voltage by detecting the divided reference voltage.
[0013]
As an example of a configuration for generating a high voltage, the invention according to claim 7 includes the flyback transformer configured to input the reference voltage generated by the power supply circuit and generate the high voltage. There is a configuration. That is, a high voltage can be generated from the reference voltage using a general-purpose television product.
Here, when the power supply circuit receives the primary-side voltage and generates a high-potential DC reference voltage and a low-potential DC reference voltage that is a potential corresponding to the high potential, the flyback transformer has the above-described configuration. The high voltage may be generated by inputting a high-potential reference voltage. That is, a high voltage can be generated using a circuit generally used in television.
Of course, a high voltage may be generated from the reference voltage using a predetermined high voltage generation circuit other than the flyback transformer.
[0014]
As an example of a configuration for changing the reference voltage, the invention according to claim 8 is characterized in that the power supply circuit turns on and off the primary-side voltage which is a direct current to generate a pulse-like voltage, and responds to a control voltage inputted. A pulse generation circuit capable of changing the pulse width of the same voltage, generating the reference voltage based on the pulsed voltage, and the voltage control means generating the control voltage corresponding to the reference voltage. Output to the pulse generation circuit. That is, the reference voltage can be changed using a circuit generally used in a television power supply circuit.
[0015]
When the reference voltage is changed, as in the invention according to claim 9, the voltage control means receives an operation input for a high-voltage current amount supplied to the picture tube, and sets the operation-input current amount. May be configured to control the high voltage current supplied to the picture tube. That is, since the high-voltage current flowing through the picture tube can be changed by the operation, the convenience in measuring the maximum X-ray radiation amount is improved.
Here, various configurations for receiving the operation input may be considered. For example, the operation input may be received from a button provided on the video display device, or the operation input may be received from a remote control transmitter having operation keys.
[0016]
By the way, the above-mentioned television and the video display device may be used independently, or may be used in a state of being incorporated in another device.
In the method of controlling the high voltage so that the protection circuit is stopped immediately before the supply is stopped, the process proceeds according to a predetermined procedure, and an invention exists in the procedure at the root thereof. Therefore, an invention according to claim 10 is a voltage control method for a video display device including a protection circuit for stopping supply of the high voltage to the picture tube when the high voltage supplied to the picture tube becomes equal to or higher than a predetermined voltage. The high voltage is generated so as to be changeable, a DC reference voltage that changes corresponding to the high voltage is detected, and the protection circuit supplies the high voltage to the picture tube while increasing the high voltage. And the control for generating the high voltage corresponding to the detected reference voltage immediately before the stop is detected.
[0017]
Further, there is an invention in a method of measuring the maximum X-ray radiation using the above-mentioned television and video display device. Therefore, the invention according to claim 11 is directed to a maximum X-ray radiation amount of a video display device including a protection circuit for stopping the supply of the high voltage to the picture tube when the high voltage supplied to the picture tube becomes a predetermined voltage or more. A measuring method, wherein the video display device generates the high voltage so as to be changeable, detects a DC reference voltage that changes corresponding to the high voltage, and protects the high voltage while increasing the high voltage. The circuit detects the same reference voltage immediately before stopping the supply of the same high voltage to the picture tube, performs control to generate the high voltage corresponding to the detected immediately preceding reference voltage, and responds to the immediately preceding reference voltage. When the control for generating the high voltage is performed, the maximum radiation amount of X-rays from the picture tube is measured using an X-ray radiation amount measuring device capable of measuring the X-ray radiation amount.
That is, the present invention is also applicable as a voltage control method for a video display device and a maximum X-ray radiation amount measurement method for a video display device. The device configuration according to claim 1 or claim 3 to claim 9 is applicable. It is also possible to correspond to the method.
[0018]
【The invention's effect】
As described above, according to the first, second, tenth, and eleventh aspects of the present invention, a television and a video display capable of facilitating the operation of measuring the maximum X-ray radiation amount. The present invention can provide a device, a voltage control method for an image display device, and a method for measuring the maximum X-ray radiation amount of an image display device.
According to the third aspect of the present invention, since a general-purpose power supply circuit can be used, it is possible to supply a high voltage to the picture tube immediately before the protection circuit stops supplying power with a simple circuit configuration. According to the present invention, the reference voltage immediately before the supply of the high voltage is stopped can be easily generated.
Furthermore, according to the invention according to claim 5, it is possible to improve convenience in the operation of measuring the maximum X-ray radiation amount.
[0019]
Further, according to the invention of claim 6, since it is sufficient to detect a lower voltage, it is possible to detect the reference voltage with a simpler circuit configuration.
Further, according to the invention of claim 7, it is possible to provide a specific example of the high voltage generating means, and it is possible to easily generate a high voltage using a general-purpose television product.
Further, according to the invention of claim 8, the reference voltage can be changed using a general-purpose circuit.
Further, according to the ninth aspect, it is possible to improve the convenience in the operation of measuring the maximum X-ray radiation amount.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in the following order.
(1) Schematic configuration of television:
(2) Equipment used for measuring the maximum X-ray radiation:
(3) Main configuration of television:
(4) Operation of television and method of measuring maximum X-ray radiation amount:
[0021]
(1) Schematic configuration of television:
FIG. 1 is a schematic block diagram of a configuration of a television (video display device) 100 according to an embodiment of the present invention. The operation panel and the like are not shown.
In the figure, a television 100 is a broadcast receiving apparatus, which is a tuner IC 12, a chroma IC 13 connected to the tuner IC 12, a microcomputer 11 connected to the tuner IC 12 and the chroma IC 13, and a remote controller connected to the microcomputer 11. The receiving unit 14 is provided. The tuner IC 12, the chroma IC 13, and the microcomputer 11 are connected to the IIC bus 10. When the operator operates an operation key of the remote control transmitter 15, the remote control transmitter 15 transmits an infrared remote control signal corresponding to the operation content, and the remote control receiver 14 receives the remote control signal.
The microcomputer 11 includes a CPU 11a, a ROM 11b, a RAM 11c, an on-screen display circuit (OSD) 11d, an A / D converter 11e, a D / A converter 11f, and a timer circuit (not shown) for performing various controls. Then, in accordance with a remote control signal input from the remote control receiving unit 14, the entire television 100 is controlled by serial data communication.
[0022]
Devices such as the microcomputer 11, the ICs 12, 13 and the flyback transformer (FBT) 27 are supplied with a plurality of potential DC reference voltages from the power supply circuit 40, and these devices operate using the same reference voltages. It has become. An X-ray protection circuit 30, which is a protection circuit according to the present invention, is connected to the power supply circuit 40, and a high-potential reference voltage (E1) so as to prevent X-ray emission from the picture tube (CRT) 22. Is set to a predetermined voltage or more, the power supply circuit 40 stops generating the reference voltage. Further, a reset circuit 31 is connected to the X-ray protection circuit 30. When the X-ray protection circuit 30 operates to stop the generation of the reference voltage in the power supply circuit 40, a reset signal is sent to the microcomputer 11. It operates to output and reset each part of the television 100.
[0023]
The tuner IC 12 is a tuner of a frequency synthesizer system, receives a broadcast wave of a television broadcast under the control of the microcomputer 11, converts it into an intermediate frequency signal (IF), and outputs it. Although not shown in detail, the tuner IC 12 includes a high-frequency amplifier circuit connected to the microcomputer 11, an intermediate-frequency signal output circuit connected to the high-frequency amplifier circuit and the microcomputer 11, and the like. The intermediate frequency signal output circuit includes a local oscillation circuit connected to the microcomputer 11, and a mixing circuit connected to the local oscillation circuit and the high frequency amplifier circuit. As the high-frequency amplifier circuit and the intermediate frequency signal output circuit, various television circuits that have been conventionally used can be applied.
[0024]
The high-frequency amplifier circuit has a band-pass filter, and receives a broadcast wave corresponding to a desired frequency from the antenna 12a via the band-pass filter under the control of the microcomputer 11, and amplifies to generate a high-frequency signal. And outputs it to the mixing circuit. The local oscillation circuit is constituted by a PLL (Phase Locked Loop) circuit, and based on a reference oscillation signal from a crystal oscillation circuit, a local oscillation signal having a local oscillation frequency corresponding to a desired frequency of a broadcast radio wave by the PLL circuit. Create and output 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, and outputs the intermediate frequency signal to the chroma IC 13.
[0025]
Although not shown in detail, the chroma IC 13 includes an intermediate frequency amplifying (VIF) circuit connected to the tuner IC 12, a VCO (Voltage Controlled Oscillator) circuit connected to the microcomputer 11, and a VCO circuit and a VIF circuit. It has a connected detection circuit, an AGC circuit connected to the detection circuit, a synchronization circuit connected to the detection circuit, and the like. Note that various circuits for televisions that have been conventionally used can be applied to each circuit.
The VIF circuit performs intermediate frequency amplification on the intermediate frequency signal input from the tuner IC 12 and outputs the intermediate frequency amplified intermediate frequency signal to a detection circuit. The VCO circuit can change the oscillation frequency of the oscillation signal that oscillates according to the voltage input from the microcomputer 11, and oscillates the oscillation signal at the oscillation frequency corresponding to the voltage. The detection circuit detects the intermediate frequency signal amplified by the VIF circuit based on the oscillation frequency of the oscillation signal, outputs an RGB signal to the cathode amplifier 21, and outputs an AUDIO signal to the audio amplifier 23. The detection circuit also creates 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. The synchronizing circuit generates a sawtooth-shaped horizontal / vertical drive signal (DRIVE) based on the input horizontal / vertical synchronizing signal, and outputs the signal to a deflection circuit 25 including a horizontal deflection circuit and a vertical deflection circuit.
The chroma IC 13 is connected to the OSD 11d, and can superimpose the OSD signal input from the OSD 11d on the RGB signal.
[0026]
The cathode amplifier 21 amplifies the RGB signals and supplies them to the picture tube 22. Then, the picture tube 22 performs screen display based on the amplified RGB signals. On the other hand, the audio amplifier 23 amplifies the AUDIO signal and supplies it to the speaker 24. Then, the speaker 24 outputs a sound based on the amplified AUDIO signal.
The deflection circuit 25 generates a predetermined horizontal / vertical drive current corresponding to the horizontal / vertical drive signal and supplies it to the deflection coil 26 attached to the picture tube 22 to drive the electron beam in the horizontal / vertical direction. . The high-frequency signal generated in the horizontal deflection circuit is supplied to the FBT 27. The FBT 27 receives a high-potential reference voltage and generates a high voltage (cathode voltage) to be supplied to the picture tube 22.
Then, the picture tube 22 emits an electron beam corresponding to the RGB signal toward a predetermined tube surface based on the high voltage. As a result, an image appears on the tube surface of the picture tube 22.
[0027]
(2) Equipment used for measuring the maximum X-ray radiation:
An IIC bus interface (IIC bus I / F) 10a is connected to the IIC bus 10 of the television for adjustment and inspection at the television manufacturing factory, and the television 100 can be connected to a personal computer (PC). It has become.
FIG. 2 shows the equipment used for measuring the maximum X-ray radiation amount together with the television.
In the figure, the tube surface 22 a of the picture tube 22 is arranged so as to be in front of the television 100. In the figure, an IIC bus I / F 10a is provided at the lower right of the television 100, and is connected to the PC 200 via the IIC bus cable 201 via the IIC bus I / F 10a. The PC 200 is connected to a display 202 as an output device, a keyboard 203 and a mouse 204 as input devices. When the PC 200 is connected to the IIC bus I / F 10a, the cable 201 is connected to the IIC bus I / F 10a after removing the rear cabinet 100a of the television. When a predetermined key operation is performed on the remote control transmitter 15 to set a so-called factory mode, the PC 200 can transmit various adjustment data to the television 100.
[0028]
Here, when an instruction to switch to the maximum X-ray radiation amount measurement mode is sent from the PC 200, the television 100 sets the voltage to the voltage immediately before the supply of the high voltage to the picture tube 22 is stopped, which will be described in detail later. Control the voltage. When such control is being performed, the measuring unit 80a of the X-ray radiation measuring device 80 capable of measuring the amount of X-ray radiation is brought to be pressed against the tube surface 22a of the picture tube to receive the image. The maximum amount of X-ray emission from the tube 22 is measured.
[0029]
(3) Main configuration of television:
FIG. 3 shows a main part configuration of the television 100 in a partial circuit.
The power supply circuit 40 generally includes a rectifying / smoothing circuit 41, a switching circuit 42, a transformer 43, and a DC conversion circuit 44. The rectifying and smoothing circuit 41 receives an AC voltage from a commercial AC power supply, rectifies and smoothes the AC voltage with a silicon bridge 41a and an electrolytic capacitor 41b, and converts the rectified and smoothed DC voltage to a primary voltage. The switching circuit 42 includes a pulse generation circuit 42a connected to the D / A converter 11f of the microcomputer 11, and a protection switch element 42b connected to the pulse generation circuit 42a and the X-ray protection circuit 30. . The pulse generation circuit 42a includes a switching transistor, a capacitor, a plurality of resistance elements, and the like. The pulse generation circuit 42a turns on and off a DC primary voltage to generate a pulse-like voltage, and in accordance with a control voltage input from the microcomputer 11. The pulse width of the same voltage can be changed. That is, the pulse generation circuit 42a is a voltage variable circuit that can change the magnitude of the reference voltage generated by the power supply circuit 40. Then, the magnitudes of the reference voltages E1 to E3 generated by the power supply circuit 40 can be changed.
[0030]
The transformer 43 includes a primary coil and a secondary coil wound around the same core. One end of the secondary coil is connected to the ground, and is output to the other end and two intermediate locations, for a total of three locations. A unit is provided to input the pulsed primary voltage and output three types of secondary voltages. The DC conversion circuit 44 receives three types of secondary-side voltages, rectifies them with diodes D1, D2, and D3, smoothes them with electrolytic capacitors C1, C2, and C3, respectively, and obtains three types of DC. The voltages are converted into voltages E1, E2, and E3 (E1>E2> E3). Since the reference voltages E1 to E3 are generated based on the secondary side voltage from the same transformer 43, they are set to potentials substantially proportional to each other.
[0031]
The highest potential reference voltage (high potential reference voltage) E1 is supplied to the FBT 27. The FBT 27 receives the reference voltage E1 and generates a high voltage whose voltage increases as the reference voltage E1 increases. To supply. Then, the picture tube 22 emits the electron beam toward the tube surface based on the generated high voltage. The lowest reference voltage E3 is supplied to a power supply terminal of the microcomputer 11 and the microcomputer 11 is driven by using the reference voltage E3 as a drive source. The power supply circuit 40 is a circuit that generates a reference voltage while performing feedback. Although not shown, a signal that is turned on / off according to whether the reference voltage E3 is equal to or higher than a predetermined voltage is input to the pulse generation circuit 42a. The on / off timing of the pulse generation circuit 42a is changed.
In this way, the power supply circuit 40 receives the AC voltage and generates the high-potential DC reference voltage E1 and the low-potential DC reference voltages E2 and E3 which are set to a potential substantially proportional to the high potential. The power supply circuit 40 that generates the high-potential reference voltage E1 so as to be changeable, and the FBT 27 that inputs the same reference voltage E1 and generates the high-voltage to the picture tube 22 so that the voltage can be changed, include Constitute.
[0032]
The X-ray protection circuit 30 includes a series circuit of the resistance elements R1 and R2 interposed between the power supply line of the high-potential reference voltage E1 and the ground, and the power supply line of the low-potential reference voltage E2 and the ground. A series circuit of the interposed resistive element R3 and the semi-fixed resistor VR1 (the semi-fixed resistor VR1 is on the ground side), the voltage at the intermediate connection between the resistive elements R1 and R2, and the variable semi-fixed resistor VR1 And a comparator 30a for inputting the voltage of the unit and outputting a comparison result. Therefore, by adjusting the semi-fixed resistor VR1, it is possible to change how many volts or more of the reference voltage E1 activates the X-ray protection circuit 30.
[0033]
The output of the comparator 30a is input to the protection switch element 42b and the reset circuit 31. That is, the divided voltage of the high-potential reference voltage E1 and the voltage of the variable portion of the semi-fixed resistor VR1 are compared by the comparator 30a, and when the reference voltage E1 becomes equal to or higher than a predetermined voltage by the semi-fixed resistor VR1, the protection is performed. The switch element 42b for supply shuts off the supply of the primary voltage to the transformer 43, and the reset circuit 31 resets each part of the television 100. Therefore, the X-ray protection circuit 30 causes the power supply circuit 40 to stop generating the reference voltages E1 to E3 when the high-potential reference voltage E1 becomes equal to or higher than the predetermined voltage so as to prevent the X-ray from being emitted from the picture tube 22. . In other words, when the high voltage supplied to the picture tube 22 becomes equal to or higher than the predetermined voltage, the supply of the high voltage to the picture tube 22 is stopped.
In the present embodiment, three types of reference voltages are generated. However, the present invention is not limited to the number of types of reference voltages. For example, the present invention provides a power supply circuit that generates only one type of reference voltage. The present invention is also applicable to a video display device having the same.
[0034]
Further, a voltage dividing circuit 50 in which resistance elements (resistance circuits) R4 and R5 having a predetermined resistance value are connected in series is provided between the power supply line of the low-potential reference voltage E2 and the ground. The intermediate connecting portion 51 of the voltage dividing circuit 50 is connected to the A / D converter 11e of the microcomputer 11, and the A / D converter 11e is adapted to divide the voltage of the intermediate connecting portion 51, that is, the low potential reference voltage E2. A voltage is input and converted to a digital voltage value. Therefore, the voltage dividing circuit 50 and the microcomputer 11 detect the voltage of the intermediate connecting portion 51 of the voltage dividing circuit 50, thereby detecting the DC reference voltage that changes in response to the high voltage supplied to the picture tube 22. The reference voltage detecting means is constituted. Then, since it is sufficient to detect a voltage lower than the reference voltage E2, the reference voltage can be detected with a simple circuit configuration.
[0035]
Further, the microcomputer 11 writes digital control voltage data for causing the pulse generation circuit 42a to control the reference voltages E1 to E3 to the built-in D / A converter 11f, so that the D / A converter 11f performs control corresponding to the control voltage data. The signal is converted into a voltage and output to the pulse generation circuit 42a. Then, the pulse generation circuit 42a generates a pulse corresponding to the input control voltage, and turns on and off the primary DC voltage from the rectification and smoothing circuit 41 according to the pulse.
[0036]
(4) Operation of television and method of measuring maximum X-ray radiation amount:
Hereinafter, the operation of the television according to the present embodiment will be described together with the procedure for measuring the maximum X-ray radiation amount.
First, an operator of a television manufacturing factory connects the PC 200 to the television 100 as shown in FIG. 2 and performs a predetermined key operation for setting the television 100 to the factory mode using the remote control transmitter 15. At the same time, the PC 200 activates a predetermined adjustment inspection program for the factory mode. With the function of the adjustment inspection program, the PC 200 can receive an operation input for an instruction to set the maximum X-ray radiation measurement mode from the keyboard 203 or the like and transmit the instruction to the television 100. By inputting an operation for an instruction to set the maximum X-ray radiation dose measurement mode from the above, the instruction can be transmitted to the television 100. Then, when the television 100 obtains an instruction to switch to the maximum X-ray radiation measurement mode during the factory mode, the television 100 performs control processing of the high voltage supplied to the picture tube 22.
[0037]
The microcomputer 11 repeatedly performs a process of receiving an input of a remote control signal from the remote control transmitter 15 via the remote control reception unit 14. When a remote control signal corresponding to a key operation for setting a factory mode is input, a predetermined factory mode is input. When a flag is set and a remote control signal corresponding to a key operation for canceling the factory mode is input, the factory mode flag is reset. When the factory mode flag is set, the factory mode processing shown in FIG. 4 is repeated. This process is performed by the CPU 11a of the microcomputer 11.
First, it is determined whether or not an instruction to enter the maximum X-ray radiation measurement mode has been input via the IIC bus I / F 10a (step S105). If the instruction has not been input, this flow is terminated. Then, when this flow is started again, it is determined in step S105 whether or not an instruction to enter the maximum X-ray radiation measurement mode has been input.
[0038]
When an instruction to enter the maximum X-ray radiation measurement mode is input, the X-ray measurement flag provided in a predetermined area of the RAM 11c is reset (for example, 0 is substituted for the X-ray measurement flag) (step S110). Next, for example, as shown in FIG. 5, a message prompting the user to input a high-voltage current amount to be supplied to the picture tube 22 is displayed on the picture tube 22 via the OSD 11d. An operation input regarding the amount of high-voltage current supplied to the CPU 11 is received (step S115), and the input current amount is stored in a predetermined area of the RAM 11c (step S120). In the example of the figure, the operator can operate and input a current amount by operating a cursor key or a number key provided on the remote control transmitter 15, and presses a confirmation key provided on the remote control transmitter 15 to input the operation amount. Can be terminated. Of course, an operation input about the amount of current may be received from an operation button provided on the main body of the television 100, or an input about the amount of current may be received from the operation button from a PC connected to the television 100.
[0039]
Thereafter, a digital voltage value corresponding to the divided voltage of the low-potential reference voltage E2 is read from the A / D converter 11e and acquired (step S125). This stage corresponds to the timing t1 in FIG. 6 showing a timing chart of the reference voltage E2, the divided voltage of the reference voltage E2, and the high voltage supplied to the picture tube 22. Further, the read voltage value is stored in a predetermined area of the RAM 11c (step S130). The predetermined area is a storage area for storing a voltage value corresponding to the reference voltage.
[0040]
After the read voltage value is stored in the RAM 11c, a predetermined value V1 is added to the read voltage value (Step S135), and the added digital voltage value is written to the A / D converter 11e (Step S140). This stage corresponds to the timing t2 in FIG. Then, the A / D converter 11e converts the control voltage into a control voltage whose voltage increases as the voltage value increases in accordance with the digital voltage value, and outputs the control voltage to the pulse generation circuit 42a. The pulse generation circuit 42a turns on / off the primary side voltage so as to have a pulse width corresponding to the input control voltage, and the DC voltage generation circuit 44 increases the control voltage according to the pulse width. The EBT is generated, and the FBT 27 generates a high voltage corresponding to the reference voltage E1 and increases the voltage as the reference voltage E1 increases, and supplies the high voltage to the picture tube 22. Therefore, the higher the voltage supplied to the picture tube 22, the greater the voltage value corresponding to the digital voltage value written in the A / D converter 11e.
[0041]
Thereafter, a digital voltage value corresponding to the divided voltage of the low-potential reference voltage E2 is read and acquired again from the A / D converter 11e (step S145). This stage corresponds to the timing t3 in FIG. Accordingly, the reference voltage E2 increases by a voltage corresponding to the predetermined value V1 from the initial state, and the high voltage supplied to the picture tube 22 also increases from the initial state.
Then, it is determined whether or not the obtained voltage value is equal to or less than a predetermined voltage threshold value V0 (step S150). When the X-ray protection circuit 30 operates, the power supply circuit 40 stops supplying the reference voltages E1 to E3, and the reference voltage E2 becomes almost 0. Therefore, by performing the same determination processing, whether the X-ray protection circuit 30 is operating. Can be determined. That is, in the determination processing, it is determined whether or not the X-ray protection circuit has caused the power supply circuit to stop generating the reference voltage based on the digital voltage value. Of course, when a signal indicating that the supply of the reference voltage is stopped is generated from the X-ray protection circuit 30, the X-ray protection circuit 30 is activated by reading the signal through the I / O port of the microcomputer 11. It is possible to determine whether or not.
[0042]
If the obtained voltage value is larger than the voltage threshold value V0, the digital voltage value to which the predetermined value V1 has been added in step S135 is stored in the RAM 11c (step S155). Of course, the voltage value acquired from the A / D converter 11e in step S145 may be stored. Then, the process returns to step S135. Then, the predetermined value V1 is further added to the digital voltage value and written to the D / A converter 11f, so that the reference voltage E2 increases stepwise as shown at timings t4 and t6 in FIG. Therefore, when the A / D converter 11e is read at timings t5 and t7, the voltage value is further increased. At the timing t8, since the high-potential reference voltage E1 becomes equal to or higher than the predetermined voltage, the comparator 30a of the X-ray protection circuit 30 outputs a signal to the protection switching element 42b to cut off the supply of the primary voltage to the transformer 43. . Then, the power supply circuit 40 stops supplying the reference voltages E1 to E3, and the high-potential reference voltage E1 and the low-potential reference voltage E2 become almost zero. The reference voltage E3 is supplied with power from a capacitor having a relatively large capacitance to operate the microcomputer 11, and is kept at a predetermined voltage or more for a certain period.
[0043]
At this time, since the voltage value acquired from the A / D converter 11e is equal to or less than the voltage threshold V0 (timing t9), the X-ray measurement flag is set (for example, 1 is substituted for the X-ray measurement flag) (step S160). This flow ends. That is, in the process of step S160, it is determined that the X-ray protection circuit has stopped generating the reference voltage. Here, the signal from the comparator 30a of the X-ray protection circuit is also input to the reset circuit 31, and the reset circuit 31 outputs a reset signal to the microcomputer 11. Then, the microcomputer 11 inputs the reset signal from a reset terminal (not shown), and starts the reset process shown in FIG. 7 by an interrupt process.
[0044]
When the reset process is started, first, it is determined whether or not the X-ray measurement flag is set (Step S205). When the X-ray measurement flag is not set, the mode is not the maximum X-ray radiation dose measurement mode, and other reset processing (not shown) is performed. When the X-ray measurement flag is set, the digital voltage value and current amount stored in steps S155 and S120 are read from the RAM 11c (step S210). Here, the read digital voltage value is a voltage value corresponding to immediately before the X-ray protection circuit stops generating the reference voltage. Next, a current amount control process for controlling the high voltage current supplied to the picture tube 22 is performed based on the read current amount (step S215). In this current amount control process, for example, an adjustment signal for making the contrast or the light a predetermined amount according to the current amount input by operation is created and output to the chroma IC 13 so that the high voltage of the high The amount of current can be controlled. As described above, the high-voltage current flowing through the picture tube can be changed by the operation, which is convenient when measuring the maximum X-ray radiation amount.
[0045]
After performing the current amount control process, the read digital voltage value is written to the D / A converter 11f (step S220). This stage corresponds to the timing t10 in FIG. Then, the A / D converter 11e converts the voltage into a control voltage corresponding to a digital voltage value and outputs the control voltage to the pulse generation circuit 42a. The pulse generation circuit 42a has a pulse width corresponding to the input control voltage. The primary side voltage is turned on / off, the DC conversion circuit 44 generates reference voltages E1 to E3 according to the pulse width, and the FBT 27 generates a high voltage corresponding to the reference voltage E1 and supplies it to the picture tube 22. Therefore, the high voltage supplied to the picture tube 22 is controlled to a voltage corresponding to a digital voltage value immediately before the X-ray protection circuit stops generating the reference voltage. Therefore, in the process of step S220, control for adjusting the reference voltage by creating a control voltage so that the low-potential reference voltage E2 becomes a voltage corresponding to the digital voltage value and outputting the control voltage to the voltage variable circuit is performed become.
As described above, the microcomputer 11 detects the reference voltage immediately before the X-ray protection circuit 30 stops supplying the high voltage to the picture tube 22 with reference to the case where the high voltage is increased by the power supply circuit 40 and the FBT 27, and detects the reference voltage. A voltage control means for controlling the power supply circuit 40 and the FBT 27 to generate a high voltage corresponding to the immediately preceding reference voltage.
[0046]
In the present embodiment, in order to inform the worker that the maximum X-ray radiation amount can be measured, the maximum X-ray radiation amount from the picture tube 22 such as “XSENSE TECHNOLOGY” is measured. Is displayed on the picture tube 22 via the OSD 11d (step S225). Also, predetermined audio data corresponding to prompting measurement of the maximum X-ray radiation amount is output to the chroma IC 13 and predetermined audio is output from the speaker 24 (step S230). Therefore, when a reference voltage capable of measuring the amount of X-ray radiation is generated, the fact can be known from the display or the audio output, which is convenient when measuring the maximum X-ray radiation.
[0047]
Therefore, the operator uses the X-ray radiation amount measuring device 80 to bring the measuring unit 80a against the tube surface 22a of the picture tube 22 and move the X-ray radiation amount while moving on the tube surface 22a. By reading the maximum value, the maximum amount of X-ray radiation from the picture tube 22 is measured. At this stage, in the television 100, control is performed to generate a high voltage corresponding to the reference voltage immediately before the X-ray protection circuit 30 operates. Therefore, as in the prior art, turning the semi-fixed resistor to raise the reference voltage to the voltage immediately before the X-ray protection circuit is activated, or turning on the power after the X-ray protection circuit is activated, and then turning on the X-ray protection circuit It is not necessary to adjust the semi-fixed resistor so as to lower the reference voltage to the voltage immediately before the operation of the device, and the operation of measuring the maximum X-ray radiation becomes easy.
[0048]
Thereafter, it is determined whether or not the measurement of the maximum X-ray radiation amount has been completed, for example, by detecting whether or not the end key of the remote control transmitter 15 has been operated (step S235). This determination processing is repeatedly performed until the measurement of the maximum X-ray radiation amount is completed. Of course, it may be determined whether or not the measurement has been completed by using the timer circuit of the microcomputer 11 to determine whether or not a predetermined time has elapsed. When it is determined that the measurement has been completed, since the reference voltage and the high voltage are in the rising state, the initial digital voltage value is written in the D / A converter 11f (step S240), and the X-ray measurement flag is set. Is reset (step S245), and this flow ends. Then, at timing t11 in FIG. 6, the high voltage supplied to the picture tube 22 drops to the voltage in the initial state.
[0049]
As described above, when the video display device of the present invention is used, the high voltage immediately before the X-ray protection circuit stops the supply is automatically supplied to the picture tube based on the case where the high voltage is increased. Therefore, it is possible to measure the maximum amount of X-ray radiation. Therefore, the operation of increasing the high voltage supplied to the picture tube to the voltage immediately before the operation of the X-ray protection circuit is not required, and the operation of measuring the maximum X-ray radiation amount can be facilitated.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a configuration of a television according to an embodiment of the present invention.
FIG. 2 is a diagram showing an apparatus used for measuring a maximum X-ray radiation amount together with a television.
FIG. 3 is a diagram partially showing a circuit of a main part configuration of the television.
FIG. 4 is a flowchart showing a factory mode process.
FIG. 5 is a diagram showing an example of a display screen for prompting input of a high-voltage current amount.
FIG. 6 is a timing chart of a reference voltage E2, a divided voltage of the reference voltage E2, and a high voltage supplied to a picture tube.
FIG. 7 is a flowchart illustrating a reset process.
FIG. 8 is a diagram showing a main configuration of a video display device according to a conventional example.
[Explanation of symbols]
10… IIC bus
10a ... IIC bus interface
11 ... microcomputer
11a CPU
11b ROM
11c ... RAM
11d ... On-screen display circuit
11e A / D converter
11f ... D / A converter
12 ... Tuner IC
12a ... antenna
13 ... Chroma IC
14 Remote control receiver
15 Remote control transmitter
21 ... Cathode amplifier
22 ... picture tube (CRT)
22a ... tube surface
23 ... Audio amplifier
24 ... Speaker
25 ... deflection circuit
26 ... deflection coil
27 ... Flyback transformer (FBT)
30 X-ray protection circuit
30a ... Comparator
31 ... Reset circuit
40 ... Power supply circuit
41 ... Rectifier smoothing circuit
42 ... Switching circuit
42a ... Pulse generation circuit
42b ... Protection switch element
43… Transformer
44 DC conversion circuit
50 ... voltage dividing circuit
51 ... middle connection part
80 X-ray radiation dose measuring device
80a ... Measurement unit
100 ... Television
200 ... Personal computer

Claims (11)

A power supply circuit that receives an AC voltage and generates a high-potential DC reference voltage and a low-potential DC reference voltage that is substantially proportional to the high potential; A flyback transformer that generates a high voltage whose voltage increases as the high-potential reference voltage increases, a picture tube that emits an electron beam toward a predetermined tube surface based on the high voltage, and X from the picture tube An X-ray protection circuit for stopping the generation of the reference voltage when the high-potential reference voltage becomes equal to or higher than a predetermined voltage so as to prevent radiation of the line; In a television having a voltage variable circuit capable of changing the length,
The voltage variable circuit can change the magnitude of the reference voltage generated by the power supply circuit based on the input control voltage,
A voltage dividing circuit which is connected in series with a resistance circuit having a predetermined resistance value and is interposed between a power supply line of the low potential reference voltage and the ground;
An A / D converter for inputting the voltage of the intermediate connection portion of the voltage dividing circuit and converting the voltage to a digital voltage value; and a RAM for storing the same voltage value, wherein the control stepwise increases the reference voltage. A digital voltage value is obtained from the A / D converter while increasing the reference voltage by generating a voltage and outputting the voltage to the voltage variable circuit, stored in the RAM, and the X-ray is generated based on the voltage value. The protection circuit determines whether or not the power supply circuit has stopped generating the reference voltage, and when the X-ray protection circuit determines that the generation of the reference voltage has stopped, the X-ray protection circuit from the RAM determines that the X-ray protection circuit has stopped generating the reference voltage. A voltage value corresponding to immediately before stopping generation of the reference voltage is read out, and the control voltage is created so that the low-potential reference voltage becomes a voltage corresponding to the voltage value. Television, characterized by comprising a microcomputer for control for adjusting the reference voltage by outputting the odd circuits. A video display device comprising a protection circuit for stopping supply of the high voltage to the picture tube when the high voltage supplied to the picture tube is equal to or higher than a predetermined voltage,
High voltage generation means for generating the high voltage in a changeable manner;
Reference voltage detection means for detecting a DC reference voltage that changes in response to the high voltage,
The protection circuit detects the reference voltage immediately before stopping the supply of the high voltage to the picture tube on the basis of the case where the high voltage is increased by the high voltage generating means, and the detected voltage is detected. And a voltage control means for controlling the high voltage generation means to generate the high voltage corresponding to the immediately preceding reference voltage. The high voltage generation means has a power supply circuit that receives a primary voltage and generates a DC reference voltage on the secondary side, and generates the high voltage in which the voltage increases as the reference voltage increases,
The voltage control means causes the reference voltage detection means to detect the same reference voltage immediately before the protection circuit stops supplying the high voltage to the picture tube while increasing the reference voltage to the power supply circuit, and the detected voltage is detected. 3. The video display device according to claim 2, wherein the power supply circuit generates the reference voltage so that the reference voltage becomes the reference voltage immediately before. The voltage control means has a storage area for storing a voltage value corresponding to the reference voltage, and causes the reference voltage detection means to detect the reference voltage while increasing the reference voltage in the power supply circuit step by step. A voltage value corresponding to the detected reference voltage is acquired and stored in the storage area, and the protection circuit determines whether or not the supply of the high voltage to the picture tube has been stopped. When it is determined that the supply of the high voltage has been stopped, the protection circuit reads the voltage value corresponding to immediately before stopping the supply of the high voltage from the storage area, and sets the voltage value to the reference voltage corresponding to the voltage value. 4. The video display device according to claim 3, wherein said reference voltage is generated by a power supply circuit. The voltage control means, when causing the power supply circuit to generate the reference voltage so as to have a reference voltage corresponding to a voltage value corresponding to immediately before stopping the supply of the high voltage, the X-rays from the picture tube. The image display device according to claim 4, wherein a message prompting the user to measure the radiation amount is output to the outside. The reference voltage detection means includes a voltage dividing circuit connected between a power supply line of the reference voltage and a ground while connecting a resistance circuit having a predetermined resistance value in series, and detects a voltage of an intermediate connection portion of the voltage dividing circuit. The image display device according to claim 3, wherein the reference voltage is detected by detecting the voltage. 7. The high voltage generating means according to claim 3, further comprising a flyback transformer that receives the reference voltage generated by the power supply circuit and generates the high voltage. Video display device. The power supply circuit includes a pulse generation circuit that turns on and off the primary-side voltage that is DC to generate a pulsed voltage and that can change a pulse width of the same voltage in accordance with an input control voltage. Generating the reference voltage based on the pulsed voltage,
8. The video display device according to claim 3, wherein the voltage control means generates the control voltage corresponding to the reference voltage and outputs the control voltage to the pulse generation circuit. The voltage control means receives an operation input for a high-voltage current amount supplied to the picture tube, and controls the high-voltage current supplied to the picture tube such that the operation input current amount is obtained. The video display device according to any one of claims 2 to 8, wherein A voltage control method for a video display device including a protection circuit for stopping supply of the high voltage to the picture tube when the high voltage supplied to the picture tube becomes a predetermined voltage or more,
The high voltage is generated so as to be changeable, a DC reference voltage that changes corresponding to the high voltage is detected, and the protection circuit stops supplying the high voltage to the picture tube while increasing the high voltage. A voltage control method for a video display device, comprising: detecting the same reference voltage immediately before performing the control, and performing control to generate the high voltage corresponding to the detected reference voltage immediately before. A maximum X-ray radiation amount measuring method for a video display device having a protection circuit for stopping supply of the high voltage to the picture tube when the high voltage supplied to the picture tube becomes equal to or higher than a predetermined voltage,
In the video display device, the high voltage is generated so as to be changeable, and a DC reference voltage that changes corresponding to the high voltage is detected, and while the high voltage is being increased, the protection circuit is configured to operate with respect to the picture tube. Detecting the same reference voltage immediately before stopping the supply of the same high voltage, performing control to generate the high voltage corresponding to the detected reference voltage immediately before;
When the control for generating the high voltage corresponding to the immediately preceding reference voltage is being performed, the maximum radiation of X-rays from the picture tube using an X-ray radiation amount measuring device capable of measuring the amount of X-ray radiation A method for measuring a maximum X-ray radiation amount of an image display device, comprising measuring an amount of radiation.

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