JP3219288B2 - Lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a light source for a display device of an information device equipped with an arithmetic processing unit.

[0002]

2. Description of the Related Art Conventionally, a lighting device of a light source for a display device of information equipment has been conventionally known as a technical report of the Television Society of Japan, IPD10.
5-2, February 25, 1986, p. As described in 5 to 8, a liquid crystal display is generally composed of a DC power supply, an inverter circuit that uses the DC power supply as a power supply, and a fluorescent lamp that is lit by a high-frequency high voltage converted by the inverter circuit. It is said to be a backlight. In the liquid crystal backlight, when a DC power supply is connected to an inverter circuit, a fluorescent lamp is turned on and emits light, and by adjusting a variable resistor attached to the inverter circuit,
The light emission of the fluorescent lamp can be adjusted. Also,
For example, an ON / OFF command can be sent from the main body of the arithmetic processing device by keyboard input, for example, and light emission or operation can be stopped in accordance with the command.

[0003]

In the above prior art, the operation can be controlled by a unidirectional ON / OFF command from an arithmetic processing unit. Fine control cannot be performed in accordance with the use conditions of the main body of the device. For example, in order to obtain high visibility on the liquid crystal screen, it is necessary to increase the power consumption of the lighting device to make it brighter, but when the device is used in a place with a high ambient temperature, the operation of the lighting device or the arithmetic processing device is required. If the temperature rises and continues to operate with the same power consumption, the lighting device or the arithmetic processing device will fail. Therefore, it is necessary to suppress the power consumption and lower the operating temperature of the lighting device. In such a case, it is necessary not only to control from one direction but also to feed back the temperature on the lighting device side and the arithmetic processing device side, and to control the power consumption of the lighting device based on the result.

Further, the above-mentioned prior art uses only one of the dimming methods of dimming by a variable resistor and dimming by a keyboard input. Complications were inevitable.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to automatically control the optimum operating conditions that provide the best visibility and do not impair the reliability of the equipment, according to the use condition and environment of the equipment. Another object of the present invention is to provide an easy-to-use lighting device for a liquid crystal backlight which enables both dimming by a variable resistor and dimming by a keyboard input with a simple circuit.

[0006]

SUMMARY OF THE INVENTION In order to achieve this object,
Therefore, in the present invention, an information device having an arithmetic processing device
DC power supply as the light source for the image display device
In a lighting device that lights up in a state, a control circuit and the control circuit
Switch on / off operation by road output drive signal
A control element, and the control circuit controls the arithmetic processing.
Connected to the
The control circuit controls both digital and analog input values.
Input to determine the operating state of the switching element.
The power supplied to the light source is controlled so that the analog input value
The analog / digital converter of the control circuit
After being converted to digital values,
Input to one input and the digital input value is
Input to another input of the selection circuit, and the selection circuit
Output value of log / digital converter, above digital input
Select one of the values to drive the control circuit
Output to any one of the above analog input values
Select one and input to the above analog / digital converter
To do it.

Further, in a lighting device for lighting a light source for an image display device of an information device having an arithmetic processing unit using a DC power supply as a power supply, a control circuit and a switching element which is turned on / off by an output drive signal of the control circuit. And the control circuit is connected to the arithmetic processing unit by bidirectional information communication means, and the control circuit inputs both a digital input value and an analog input value to determine an operation state of the switching element. Controlling the power supplied to the light source, converting the analog input value into a digital value by an analog / digital converter of the control circuit, and then inputting the digital value to one input of a selection circuit of the control circuit; A digital input value is input to another input of the selection circuit, and the selection circuit performs the analog / digital conversion. One of the output value and the digital input value is selected and output to the drive control circuit of the control circuit, and the selection circuit uses the digital data of the digital input value to output the output value of the analog / digital converter and the digital input value. Select digital input values. Further, a lighting device for lighting a light source for an image display device of an information device having an arithmetic processing device using a DC power supply as a power supply includes a control circuit, and a switching element that is turned on / off by an output drive signal of the control circuit. The control circuit is connected to the arithmetic processing unit by bidirectional information communication means, and the control circuit inputs both a digital input value and an analog input value to determine an operation state of the switching element; The power supplied to the light source is controlled, and the analog input value is converted into a digital value by an analog / digital converter of the control circuit, and then input to one input of a selection circuit of the control circuit, and the digital input value Is input to another input of the selection circuit, and the selection circuit outputs an output value of the analog / digital converter, Selects either the serial digital input value is output to the drive control circuit of the control circuit,
The selection circuit selects the output value of the analog / digital converter and the digital input value according to the output value of the analog / digital converter. Further, a lighting device for lighting a light source for an image display device of an information device having an arithmetic processing device using a DC power supply as a power supply includes a control circuit, and a switching element that is turned on / off by an output drive signal of the control circuit. The control circuit is connected to the arithmetic processing unit by bidirectional information communication means, and the control circuit inputs both a digital input value and an analog input value to determine an operation state of the switching element; The power supplied to the light source is controlled, and the analog input value is converted into a digital value by an analog / digital converter of the control circuit, and then input to one input of a selection circuit of the control circuit, and the digital input value Is input to another input of the selection circuit, and the selection circuit outputs an output value of the analog / digital converter, One of the digital input values is selected and output to the drive control circuit of the control circuit, and one of the plurality of analog input values is selected and input to the analog / digital converter. The plurality of analog input values is a value indicating the operating state of the switching element when the electrode of the light source is preheated, or a value indicating the operating state of the switching element when the light source is started,
Alternatively, a value indicating the operation state of the switching element when the light source is turned on, or a value indicating the operation state of the switching element when the light source or the lighting device is abnormal is set. Also, in a lighting device for lighting a light source for an image display device of an information device having an arithmetic processing device using a DC power supply as a power supply, a control circuit and an on / off operation performed by an output drive signal of the control circuit to perform the light operation.
A switching element for controlling the power supplied to the power source, the control circuit is connected to the arithmetic processing unit by bidirectional information communication means, and data output from the control circuit via the information communication means is Digital data indicating the operation state of the switching element is used.

[0008]

The function of controlling the brightness of a light source is generally performed by adjusting the volume of a connected variable resistor. This method has the advantage that it can be realized with a simple configuration, but when the use conditions of equipment change. In order to operate in accordance with the above, it is necessary to add a peripheral circuit, and for that purpose, complication is inevitable. Therefore, in the present invention, by providing a bidirectional information communication means between the control circuit and the arithmetic processing unit, it is possible to optimally control the operation timing of the switch element in accordance with the use condition. A device for detecting the condition is provided inside the lighting device,
While detecting an abnormality of the lighting device itself, while sending control data of the lighting device from the arithmetic processing device to the control circuit,
On the other hand, the detection result is fed back to the arithmetic processing unit so that the arithmetic processing unit can control the digital value. Further, if necessary, forcible control can be performed on the side of the main body in which the arithmetic processing device is incorporated, for example, due to an accident due to a power supply, a short circuit, or the like.

An analog input value indicating the operation timing of the switch element is once converted from analog to digital, and is input to one input of a selection circuit. A digital value indicating the operation timing of the switch element is input to the other input of the selection circuit. Therefore, one of the values is input to the control circuit, and the operation timing of the switch element is determined according to the value. An input terminal for selection may be provided for selection between a digital value and an analog input value from the arithmetic processing unit. However, by switching according to the input digital value or analog input value, the number of input terminals can be increased. Can be prevented. That is, if the input digital value is within a certain range, the control is performed by the digital input value, and if the input digital value is out of the certain range, the control is performed according to the analog input value.

As an operation at the time of starting a fluorescent lamp used as a light source, it is important for the life of the filament that the filament be preheated and the filament temperature becomes sufficiently high before the filament is turned on by applying a starting voltage. It is generally known that there is. In order to realize the above-mentioned operation at the time of starting, it is necessary to control the operation timing of each switch element for each operation state so as to be optimal. According to the control method, the input digital value can be realized by sequentially switching. The other method is a method of controlling with an analog value, in which an analog value indicating a switch element operation timing according to each operation mode such as preheating, starting voltage generation, lighting, etc. is input, and the analog / digital conversion is performed. This can be realized by sequentially switching the input terminals connected to the device.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a first embodiment of a lighting device according to the present invention, FIG. 2 is a circuit diagram showing a second embodiment of the present invention, FIG. 3 is a diagram showing an example of a switch circuit and a ballast circuit, and FIG. FIG. 5 is a circuit diagram showing a third embodiment of the present invention, FIG. 5 is a diagram showing a case where selection is made by a processing circuit based on the value of digital input data, FIG. Is a diagram showing an example of inputting analog data to an analog / digital converter, FIG. 8 is a diagram showing an example in which a plurality of analog input data is realized by a resistor, a variable resistor and a voltage source, and FIG. 9 is a diagram showing an input to the analog / digital converter. FIG. 10 is a circuit diagram showing a fourth embodiment in which an abnormal state detection circuit is connected, FIG. 11 is a diagram showing the configuration of an abnormal state detection circuit, and FIG. Fifth real Circuit diagram showing an example, FIG. 13 is a circuit diagram showing a sixth embodiment of displaying the battery life when using the battery power.

FIG. 1 shows a first embodiment of the present invention.
1 is a control circuit, 2 is a DC power supply, 3 is a switching circuit,
4 is a ballast circuit, 5 is a discharge lamp, 6 is a liquid crystal plate, 7 is a discharge lamp lighting device composed of the switching circuit 3 and the ballast circuit 4, and 8 is the discharge lamp lighting device 7, the discharge lamp 5 and the liquid crystal 6. Composed display device, 9
Is the display device 8 incorporating the arithmetic processing unit 29.
Is a bidirectional data communication means. The DC voltage of the DC power supply 2 is converted to a high-frequency voltage by being subjected to high-frequency switching by the switching circuit 3 and input to the ballast circuit 4. The ballast circuit 4 converts the high-frequency voltage into a high voltage, supplies the high-frequency voltage to the discharge lamp 5, and lights the discharge lamp 5. After lighting, the discharge lamp 5 is stably lit by the operation of the ballast circuit 4. Light emitted from the discharge lamp 5 is visually recognized through the liquid crystal plate 6. The liquid crystal plate 6 is controlled by the control device 9 to form an image. The control circuit 1 and the arithmetic processing unit 29 are connected by a two-way information communication means 27. The control data of the lighting device 7 is sent from the arithmetic processing unit 29 to the control circuit 1 and the control circuit 1 is connected to the arithmetic processing unit 29. The operation processing device 29 receives the data of the operation state,
It performs arithmetic processing and sends out control data to the control circuit 1. Therefore, depending on the environment in which it is used,
It is possible to accurately control the discharge lamp lighting device.

In FIG. 2 showing the second embodiment, 10 is a drive control circuit of the switching circuit 3, 11 is an input data processing circuit, 12 is digital input data, and 13 is analog input data. The reference numerals indicate the same or equivalent parts as those shown in FIG. That is,
It can be controlled from either digital input data 12 or analog input data 13.
The operation timing of the control signal of the switch element output from the drive control circuit 10 is changed according to the output of the input data processing circuit 11. FIG. 3 shows an example of the switching circuit 3 and the ballast circuit 4. In FIG.
1, 32 and 33 indicate switch elements, respectively.
4 is a choke coil, 35 is a capacitor, and 36 is a starting capacitor. The switch elements 30 and 33 and 31 and 32 perform ON / OFF operations in the same phase, and the switch elements 30 and 31 perform ON / OFF operations in the opposite phase.
Therefore, a high-frequency rectangular wave is input to the ballast circuit 4. When the discharge lamp 5 is not turned on yet, the ballast circuit 4 can be equivalently represented by a series circuit of the choke coil 34 and the combined capacitance of the capacitors 35 and 36. ON / OFF of switch elements 30, 31, 32 and 33
By setting the OFF frequency near the resonance frequency of the series equivalent circuit, a high voltage is generated at both ends of the starting capacitor 36, and the discharge lamp 5 is turned on. After lighting, a current substantially determined by the combined impedance of the choke coil 34, the capacitor 35, and the discharge lamp 5 stably flows through the discharge lamp 5. Since the impedance of the choke coil 34 and the capacitor 35 depends on the frequency, the current flowing through the discharge lamp 5 can be controlled by controlling the ON / OFF frequency of the switch elements 30, 31, 32, and 33. It is possible.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention, and shows the configuration of the input data processing circuit 11 of the second embodiment shown in FIG. In FIG. 4, 14 is an analog / digital converter, 15 is a digital selection circuit, and 16 is digital control data. The analog input data 13 is converted into a digital value by an analog / digital converter 14, and then input to one input of a selection circuit 15, and the digital input data 12 is input to the other input of the selection circuit 15. One of the digital control data is output. The selection of the analog input data 13 and the digital input data 12 is performed based on the value of the analog input data 13 or the digital input data 12, as shown in FIG. FIG. 5 shows a case where selection is made based on the value of the digital input data 12. In this example, 3-bit binary data is used as the digital input data, and when the digital input data is other than 1, 1, 1, the digital input data is selected. Is output from the selection circuit 15, and when it is 1, 1, 1, a value obtained by analog / digital conversion of the analog input data 13 is output. In the case shown in FIG. 6, a similar determination is made based on the value obtained by converting the analog input data 13 into analog / digital data.

The optimum value of the drive frequency of the switch element differs depending on the state of the discharge lamp 5, as can be understood from the description of FIG. That is, the frequency must be changed when a starting voltage is generated and when dimming is performed, and when a hot cathode lamp is preheated, or when a discharge lamp or a device becomes abnormal, etc. When controlling with the digital input data 12, the input digital value may be changed. However, when controlling with the analog input data 13, the variable resistor is generally used as the analog input means. Can not change the frequency.
Therefore, as shown in FIG. 7, the analog input data 13 input to the analog / digital converter 14 is selected from a plurality of analog input data 17, 18, and 19 by the selection switch 20. The selection switch 20 is switched by a switching signal output from the drive control circuit 10. FIG. 8 is a diagram showing an example in which a plurality of analog input data are realized by resistors 22, 23 and 25, a variable resistor 21, and a voltage source 26. For example, the variable resistor 21 is set to a resistance value indicating an operation frequency at the time of dimming, and the resistors 22, 23, and 24 are set to resistance values indicating an operation frequency at the time of starting voltage generation, preheating, and abnormal time, respectively. Then, if necessary, a resistor to be grounded is selected by the selection switch 20, and the voltage division ratio of the voltage source 26 is changed.
The voltage input to the analog / digital converter 14 is changed. FIG. 9 is a diagram showing the switching timing.

FIG. 10 is a circuit diagram showing a fourth embodiment in which a detection circuit 28 for detecting an abnormal state as described above is connected. The internal configuration of the detection circuit 28 is shown in the circuit diagram of FIG. 11, 37, 38, 39 and 40
Is a voltage comparator, 41, 42, 43, 44 and 46 are reference voltage sources, 45 is a current detection resistor, 47 is a resistor, and 48 is a thermistor. A voltage comparator 37 compares a voltage generated when part or all of the current flowing through the switching circuit 4 flows through the current detection resistor 45 with the reference voltage 41, and a current equal to or greater than a preset value flows. The output of the voltage comparator 37 is inverted. Further, the voltage value of the DC power supply 2 is compared with the reference voltages 42 and 43 by the voltage comparators 38 and 39, and when the voltage of the DC power supply 2 is equal to or higher than a preset value and equal to or lower than the predetermined value, respectively. The outputs of 38 and 39 are inverted. Further, a reference voltage 46 is supplied to a resistor 47 and a thermistor 48.
The reference voltage 44 is divided by the voltage comparator 40
When the temperature reaches a certain level or more, the output of the reference voltage 44 is inverted. An abnormality is detected by configuring as described above.

Although the above embodiment has been described by taking a discharge lamp as an example of a light source, similar effects can be obtained by using an incandescent lamp. In this case, the ballast circuit 4 becomes unnecessary. Also,
Even if the power control method is changed to the duty variable method, the same effect can be obtained.

FIG. 12 is a circuit diagram showing a fifth embodiment for coping with the processing when the light source reaches the end of its life. 12, 49 denotes a hot cathode fluorescent lamp, 50 denotes a lamp voltage detecting circuit, and other portions indicated by the same reference numerals as those in FIG. 1 indicate the same or equivalent portions as those shown in FIG. Since the lamp voltage of the hot cathode fluorescent lamp 49 increases at the end of its life, the lamp voltage is monitored by a lamp voltage detecting circuit 50, so that the hot cathode fluorescent lamp 4
9 can be detected to be near the life. Therefore, the information is sent to the control device 9 of the display device via the control circuit 1 and the bidirectional data communication means 27 to indicate that the hot cathode fluorescent lamp 49 is near the end of its life and prompt the user to replace the lamp. Accordingly, a display quality of a certain level or higher can be always maintained. As a method of detecting the end of life, a method of detecting the brightness of the light source in addition to the lamp voltage can be considered. In this case, the end of life of the cold cathode fluorescent lamp can also be detected.

FIG. 13 is a circuit diagram showing a sixth embodiment for displaying the life of the battery when a battery is used as a power supply.
In the figure, reference numeral 51 denotes a power supply voltage detection circuit, and the rest is the same as FIG. 1 showing the first embodiment. When a battery is used as the power supply, the power supply voltage gradually decreases with the use time.However, when the voltage becomes lower than the discharge end voltage of the battery, the power supply voltage drops rapidly, and the discharge lamp disappears. The voltage is monitored by the voltage detection circuit 51, and the information is sent to the control device 9 of the display device 8 via the control circuit 1 and the bidirectional data communication means 27 before the power supply voltage becomes lower than the discharge end voltage. By indicating that the battery is near, the user is encouraged to replace or charge the battery, and a lighting device for the light source for the display device which is easy to use can be realized. Further, by displaying the power supply voltage data detected by the power supply voltage detection circuit 51 or the amount corresponding to the data on the display device, there is an effect that the user can know the remaining amount of the battery.

[0020]

As described above, the lighting device according to the present invention comprises:
A switching element that uses a DC power supply as a power supply and that is turned on / off by an output drive signal of a control circuit,
In a lighting device attached to a device provided with an arithmetic processing device and for lighting a light source for an image display device connected to an output of the device, a bidirectional information communication means is provided between the control circuit and the arithmetic processing device. In addition to being able to automatically control the light source under the best operating conditions without compromising the reliability of the device, the light source can be automatically controlled according to the usage condition and environment of the device, and the variable resistance It is possible to realize a lighting device for a liquid crystal backlight in an image display, which is capable of performing both the dimming by the keyboard and the dimming by the keyboard input with a simple circuit and is easy to use.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a lighting device according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a switch circuit and a ballast circuit.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing a case where a selection is made by a processing circuit according to the value of digital input data.

FIG. 6 is a diagram illustrating a case where a selection is made by a processing circuit based on analog input data.

FIG. 7 is a diagram illustrating an input example of analog data to an analog / digital converter.

FIG. 8 is a diagram showing an example in which a plurality of analog input data is realized by a resistor, a variable resistor, and a voltage source.

FIG. 9 is a diagram illustrating switching timing of a voltage input to an analog / digital converter.

FIG. 10 is a circuit diagram showing a fourth embodiment to which an abnormal state detection circuit is connected.

FIG. 11 is a diagram showing a configuration of the abnormal state detection circuit.

FIG. 12 is a circuit diagram showing a fifth embodiment for dealing with the end of life of the light source.

FIG. 13 is a circuit diagram showing a sixth embodiment for displaying battery life when a battery is used as a power supply.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control circuit 2 DC power supply 3 Switching circuit 5 Light source 7 Discharge lamp lighting device 8 Display device 12 Digital input value 13 Analog input value 14 Analog / digital converter 15 Selection circuit 27 Bidirectional information communication means 29 Arithmetic processing unit

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Ichiro Torii 888 Fujibashi, Ome-shi, Tokyo Inside the Hitachi Industrial Co., Ltd. Ome Plant (72) Inventor Tomoyuki Tanaka 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Laboratory (72) Inventor Kenichi Onda 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Ryuichi Ikeda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Within Hitachi Image Information System Co., Ltd. (56) Reference JP-A-3-198026 (JP, A) JP-A-3-120515 (JP, A) JP-A-2 JP-A-240631 (JP, A) JP-A-64-3631 (JP, A) JP-A-1-237623 (JP, A) JP-A-63-97990 (JP, A) Open flat 2-216514 (JP, A) JitsuHiraku flat 3-6627 (JP, U) (58 ) investigated the field (Int.Cl. ^7, DB name) G09G 3/00 - 3/38 G02F 1/133 505 -580 H05B 37/00-39/10

Claims (5)

(57) [Claims] An image display for an information device having an arithmetic processing unit.
Turn on the light source for the spray device using a DC power supply as the power supply
In a lighting device, a control circuit and an output drive of the control circuit are provided.
Switching element that is turned on / off by a motion signal.
And the control circuit has a dual function with the arithmetic processing unit.
Directional information communication means, and the control circuit
Enter both the digital input value and the analog input value and
The operation state of the switching element is determined and supplied to the light source.
Power to be supplied, and the analog input value is controlled by the control circuit.
To digital value by analog / digital converter
After the conversion, one input of the selection circuit of the control circuit
The digital input value is input to other than the selection circuit.
And the selection circuit inputs the analog /
Either the output value of the digital converter or the above digital input value
Select one and output to the drive control circuit of the above control circuit
And, the lighting apparatus being characterized in that so as to enter the upper SL analog / digital converter by selecting one of a plurality of the analog input value. 2. An image display of an information device having an arithmetic processing unit.
Turn on the light source for the spray device using a DC power supply as the power supply
In a lighting device, a control circuit and an output drive of the control circuit are provided.
Switching element that is turned on / off by a motion signal.
And the control circuit has a dual function with the arithmetic processing unit.
Directional information communication means, and the control circuit
Enter both the digital input value and the analog input value and
The operation state of the switching element is determined and supplied to the light source.
Power to be supplied, and the analog input value is controlled by the control circuit.
To digital value by analog / digital converter
After the conversion, one input of the selection circuit of the control circuit
The digital input value is input to other than the selection circuit.
And the selection circuit inputs the analog /
Either the output value of the digital converter or the above digital input value
Select one and output to the drive control circuit of the above control circuit
And the selection circuit determines the digital value of the digital input value.
Output of analog / digital converter according to data
Value and the digital input value are selected.
Lighting device. 3. An image display of an information device having an arithmetic processing unit.
Turn on the light source for the spray device using a DC power supply as the power supply
In a lighting device, a control circuit and an output drive of the control circuit are provided.
Switching element that is turned on / off by a motion signal.
And the control circuit has a dual function with the arithmetic processing unit.
Directional information communication means, and the control circuit
Enter both the digital input value and the analog input value and
The operation state of the switching element is determined and supplied to the light source.
Power to be supplied, and the analog input value is controlled by the control circuit.
To digital value by analog / digital converter
After the conversion, one input of the selection circuit of the control circuit
The digital input value is input to other than the selection circuit.
And the selection circuit inputs the analog /
Either the output value of the digital converter or the above digital input value
Select one and output to the drive control circuit of the above control circuit
And the selection circuit is connected to the analog / digital converter.
Output of the above analog / digital converter depending on the output value
Value and the digital input value are selected.
Lighting device . 4. An image display of an information device having an arithmetic processing unit.
Turn on the light source for the spray device using a DC power supply as the power supply
In a lighting device, a control circuit and an output drive of the control circuit are provided.
Switching element that is turned on / off by a motion signal.
And the control circuit has a dual function with the arithmetic processing unit.
Directional information communication means, and the control circuit
Enter both the digital input value and the analog input value and
The operation state of the switching element is determined and supplied to the light source.
Power to be supplied, and the analog input value is controlled by the control circuit.
To digital value by analog / digital converter
After the conversion, one input of the selection circuit of the control circuit
The digital input value is input to other than the selection circuit.
And the selection circuit inputs the analog /
Either the output value of the digital converter or the above digital input value
Select one and output to the drive control circuit of the above control circuit
And select one of the above analog input values.
Input to the analog / digital converter.
The said plurality of analog input values, the values indicating the operating state of the switching element during the electrode preheating of the light source or the value indicating the operating state of the switching elements at starting of the light source, or in lighting of the light source, values indicating the operating state of the switching element or the light source or above,
A lighting device characterized by a value indicating an operation state of the switching element when the lighting device is abnormal . 5. A lighting device that lights a power direct current power supply source for the image display device of an information device having a processing unit, a control circuit, operated on / off by the output drive signal of the control circuit described above Power supply to light source
A switching element for controlling a force, wherein the control circuit is connected to the arithmetic processing unit by bidirectional information communication means, and data output from the control circuit via the information communication means operates the switching element. A lighting device, which is digital data indicating a state.