JPH0831582A - Back light apparatus and illuminating means with the apparatus - Google Patents

Abstract

PURPOSE:To simplify a driving circuit and lower the cost by driving a plurality of fluorescent lamps by one preheating means and one lighting means. CONSTITUTION:When a preheating means 2 is driven, preheating electric current flows in each left side filament 5L,... through a secondary side coiled wire 21b and preheating electric current flows in each right side filament 5R,... through the other secondary side coiled wire 21c and thus these filaments are preheated. Then, when a lighting means 3 is driven, voltage is applied to each fluorescent lamp FL1,... through a secondary side terminal 31b1, 31b2 and thus each fluorescent lamp FL1,... is turned on. Since these fluorescent lamps FL1,... are driven by one preheating means 2 and one lighting means 3, the driving circuit can be simplified and the cost of a back light apparatus can be lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a back light device for illuminating an information display means such as a liquid crystal panel and an illuminating means equipped with the back light device.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal panel is irradiated with light,
Various backlight devices and illuminating means equipped with the backlight devices have been proposed to facilitate recognition of information displayed on the liquid crystal panel.

Such a backlight device is provided with a fluorescent lamp (hot cathode tube) as a light source, and has a preheating means for preheating a filament of the fluorescent lamp, a lighting means for lighting the fluorescent lamp, and the like. I have it.

By the way, in a large-screen liquid crystal panel, it is necessary to make the brightness of the display unit uniform, and a backlight device having a plurality of fluorescent lamps has been used. And
In such a backlight device including a plurality of fluorescent lamps, the preheating means and the lighting means are provided as many as the fluorescent lamps.

[0005]

However, when the preheating means and the lighting means are provided as many as the number of fluorescent lamps as described above, the driving circuit and peripheral circuits become complicated correspondingly, resulting in an increase in cost and an increase in size. There was a problem of inviting. Also,
If the lighting means and the like are provided for each hot cathode tube as described above, the brightness of the hot cathode tubes becomes unequal when any of them becomes abnormal, and the display quality deteriorates.

On the other hand, in the past, the hot cathode tube and the peripheral drive circuit were always driven, but this had the problems of shortening the life of the hot cathode tube and wasting energy.

Therefore, the present invention provides a backlight device and a lighting device equipped with the backlight device, in which a plurality of hot cathode tubes are driven by one lighting means or the like to simplify the device. The purpose is.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and includes a hot cathode tube, preheating means for preheating the hot cathode tube, and a voltage applied to the hot cathode tube. A backlight device provided with a lighting means for lighting the hot cathode tube, and in particular, a plurality of the hot cathode tubes are provided, and the plurality of hot cathode tubes are preheated by one preheating means, and the plurality of hot cathode tubes are preheated. The lighting of the hot cathode tube is performed by one lighting means. In this case, the hot cathode tube has a first electrode and a second electrode arranged so as to face each other, and the preheating means includes a preheating power source and a preheating transformer. A current is passed through the electrode and the second electrode to preheat these electrodes, and the lighting means is composed of a lighting power source and a lighting transformer, and the first electrode and the second electrode are connected to each other. It is preferable to apply a voltage between them to turn on the hot cathode tube. Further, the preheating transformer has one more secondary winding than the second electrode, and the plurality of first electrodes in the plurality of hot cathode tubes are connected in series to form one secondary. A closed circuit is formed with the side winding, and a plurality of second electrodes in the plurality of hot cathode tubes independently form a closed circuit with the secondary winding of the preheating transformer. preferable. Furthermore, the preheating transformer has two secondary windings, and the plurality of first electrodes of the plurality of hot cathode tubes are connected in series to form a closed circuit together with one secondary winding. And the plurality of second electrodes in the plurality of hot cathode tubes are
The secondary winding is connected in parallel to form a closed circuit together with the secondary winding, and rectifying means is provided on each of the second electrodes so that the preheating transformer is connected to each of the secondary windings. It is preferable to allow the flow of current to the second electrode and not allow the flow of current from the lighting transformer to the preheating transformer. Furthermore, it is preferable that choke coils are respectively provided between the lighting transformer and the plurality of second electrodes. Also, a first current detecting means for detecting a current flowing through the first electrode, a second current detecting means for detecting a current flowing through the second electrode, and the first and second current detecting means. An abnormality determining means for performing abnormality determination based on a signal from
Is preferably provided. Further, the first
Current detecting means detects a current flowing between the lighting transformer and the preheating transformer and the first electrode, and the second current detecting means includes the lighting transformer and the preheating transformer. A current flowing between the transformer and the second electrode may be detected. Further, the first current detecting means includes one first coil and a first detecting device connected to the coil, and the second current detecting means has the same number of second electrodes as the second electrodes. The first coil includes two coils and a second detection device connected to the coils, and the first coil is interposed between the lighting transformer and the preheating transformer and the first electrode. Second
Coils are respectively interposed between the lighting transformer, the preheating transformer, and the second electrode, and the second coils are connected in series and the polarities of the coils are sequentially reversed.
It is preferable to form a closed circuit together with the second coil and the second detection device. Further, an abnormality display means for displaying an abnormality based on a signal from the abnormality determination means may be provided. Further, the preheating power source and the lighting power source may control the current by self-excited oscillation. Further, the preheating power source and the lighting power source may control the current by pulse width control.

On the other hand, the illumination means according to the present invention comprises a plurality of the backlight devices and a control means for driving each preheating means and lighting means of the plurality of backlight devices, and the control means In response to a signal from each abnormality determination means of each backlight device, the driving of the backlight device in which the abnormality has occurred is stopped and the brightness of the hot cathode tube in the backlight device other than the backlight device in which the abnormality has occurred is The feature is that it is increased to complement the decrease in the light amount. In this case, the control unit may include an abnormality display unit that is driven by the control unit to display an abnormality. Further, an illumination means according to the present invention includes the backlight device, an information display means for displaying information by being illuminated by the backlight device, and a display signal detection means for detecting a change in a drive signal of the information display means. And control means for driving the lighting means of the backlight device, and when the display signal detection means does not detect a change in the drive signal of the information display means for a predetermined time, the control means is The driving of the lighting means is stopped. In this case, the preheating power source and the lighting power source may control the current by self-excited oscillation. Further, the preheating power source and the lighting power source may control the current by pulse width control.

[0010]

When the preheating means is started based on the above construction, the hot cathode tube is preheated by the means, and thermionic emission from the electrodes of the hot cathode tube becomes easy. When the lighting means is driven in this state, a voltage is applied to the hot cathode tube to light the hot cathode tube. In this case, even though there are a plurality of hot cathode tubes, the preheating of the plurality of hot cathode tubes is performed by one preheating means and the lighting thereof is performed by one lighting means, so that the device is simplified accordingly. To be done.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

First, the first embodiment of the present invention will be described with reference to FIG.
It is explained along.

The backlight device 1 according to this embodiment has four
Book fluorescent lamps (hot cathode tubes) FL1, FL2, FL3, FL
4 and one preheating means 2 for preheating these fluorescent lamps FL1, ... And one lighting means 3 for applying a voltage to these fluorescent lamps FL1 ,. .

The above-mentioned preheating means 2 is provided with a lamp preheating voltage generation means 20 as a preheating power source, and the generation means is configured to generate a predetermined voltage by pulse width control (PWM control). . Further, a preheating transformer 21 is connected to the lamp preheating voltage generating means 20, and the transformer 21 has one primary winding 21a and
Five secondary windings 21b, 21c, 21d, 21e,
21f. In other words, the preheating transformer 21 of the present embodiment has five two, which is one more than the number of the fluorescent lamps FL1, ... (The number of left-side filaments described later, which is four).
It has a secondary winding.

Similarly, the lighting means 3 is also provided with a lamp lighting voltage generating means 30 as a power source for lighting, and the generating means is configured to generate a predetermined voltage by pulse width control (PWM control). ing. Further, a lighting transformer 31 is connected to the lamp lighting voltage generating means 30, and the transformer 31 has a primary winding 31a and a secondary winding 31b.

On the other hand, as is well known, each of the fluorescent lamps FL1, ... Is configured such that the first electrode 5L and the second electrode 5R are arranged at opposite ends thereof so as to face each other (hereinafter, described. For convenience of description, “right-side filament 5R” and “left-side filament 5L”) and each left-side filament (first electrode) 5L are connected in series and the secondary winding 21b of the preheating transformer 21 is connected. Together, they form a closed circuit. Therefore, the lamp preheating voltage generating means 20
Drive the primary winding 21a and the secondary winding 21
A current (hereinafter, referred to as "preheating current") according to the winding number ratio with b flows to each of the left side filaments 5L, ..., and these left side filaments 5L, ... are preheated.

The other right side filaments (second electrodes) 5R, ... Are not connected in series like the left side filaments 5L, .., and the secondary windings 21c, 21d of the preheating transformer 21. , 21e, and 21f independently form separate closed circuits. Therefore, when the lamp preheating voltage generating means 20 is driven, different preheating currents flow through the right filaments 5R, ..., Preheating these filaments 5R ,.

Further, the secondary side terminal 31b ₁ of the lighting transformer 31 is the left side filament 5 of the fluorescent lamp FL1.
It is connected to L and the lighting current is supplied from the secondary side terminal 31b ₁ to each of the left side filaments 5L, ... On the other hand, the choke coils L1, L2, L3 are attached to the right filaments 5R, ... Of the fluorescent lamps FL1 ,.
Secondary side terminal 31b _{2 of the} transformer 31 for lighting via L4
Are connected, and the four fluorescent lamps FL1, ... Are connected in parallel to the secondary winding 31b. In the present embodiment, the choke coils L1, ... Are used to stabilize the current during lighting.

Next, the operation of this embodiment will be described.

Now, when the lamp preheating voltage generating means 20 is started, this means generates a predetermined voltage for a predetermined time by pulse width control (PWM control). Then, a preheating current is generated in the secondary winding 21b of the transformer 21, and the preheating current is supplied to the left side filaments 5L, ... Connected in series.
To preheat them. In addition, another secondary winding 2
A preheating current is also induced in each of 1c, 21d, 21e, and 21f, and each preheating current flows through the right-side filament 5R, ... And preheats each filament. As a result, all the filaments 5L, ..., 5R ,.

When the preheating is completed, the lighting voltage generating means 3
0 is activated. Then, by the activation, each fluorescent lamp FL
Right filament 5R and left filament 5L of 1, ...
A predetermined voltage is applied between the fluorescent lamps FL1, FL1 and
... is lit.

Next, the effect of this embodiment will be described.

According to this embodiment, a plurality of fluorescent lamps FL1, FL1,
.. are driven by one preheating means 2 and one lighting means 3, the driving circuit and peripheral circuits are not complicated, the cost can be reduced accordingly, and the device can be simplified. Therefore, the reliability of the circuit is improved and the maintainability of the device is also improved.

Further, in this embodiment, the left side filaments 5L, ... Are connected in series, and all the left side filaments 5 are connected by only one secondary winding 21b.
It is configured to preheat L, ... Therefore,
The secondary winding of the preheating transformer 21 can be reduced accordingly, and the weight of the device can be reduced.

By the way, assuming that the number of secondary windings of the preheating transformer is only two, the filaments 5 on both the left and right sides are provided.
, L, ..., 5R ,.
If the left side filaments 5L, ... And one winding, and the right side filaments 5R, ... And another one winding form a closed circuit. Even if the lighting means 3 is driven, only one fluorescent lamp FL1 is turned on and the other fluorescent lamps FL2, FL3, FL4 are not turned on due to a voltage drop or the like. However, according to the present embodiment, the filaments connected in series are only those on the left side, and the filaments on the right side are connected as shown in the figure, so that the above problems are avoided and reliable lighting is ensured. it can.

Further, when it is attempted to light a plurality of fluorescent lamps by one lighting means, if the lighting start voltage varies and one fluorescent lamp lights up, the remaining fluorescent lamps do not light up. Although a situation occurs, according to this embodiment, since the choke coils L1, ... Are arranged for each fluorescent lamp FL1, ..., Appropriate voltage is applied to all the fluorescent lamps FL1 ,. Therefore, these fluorescent lamps FL1, ... Are lit simultaneously and stably.

In the above embodiment, the left side filaments 5L, ... Are connected in series and the right side filaments 5R, .. are independent. However, it is not limited to this, and the right side filaments 5R ,. May be connected to the left filament 5L, and the left side filaments 5L, ... May be independent.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In the backlight device 10 according to the present embodiment, the preheating transformer 121 has two secondary windings 1.
21b and 121c. The right side filaments 5R, ... Are connected in parallel to one of the secondary windings 121c, and the other secondary winding 121b is connected in series as in the first embodiment. A closed circuit is configured with the left side filaments 5L, .... Further, the common mode choke La1, serving as a rectifying means, is provided between each of the right side filaments 5R, ... And the secondary side winding 121c.
La2, La3, La4 are respectively interposed, the flow of the preheating current from the preheating transformer 12 to the respective right side filaments 5R, ... Is not hindered, and when the lighting voltage generating means 30 is started, the lighting transformer is started. Current is prevented from flowing from 31 to the left filament 5L, ... Through the preheating transformer 121, and stable operation is enabled.

Next, the effect of this embodiment will be described.

According to this embodiment, the preheating transformer 121 is used.
Since the number of windings is smaller than that in the above-described embodiment, the weight of the backlight device can be reduced. When the right side filaments 5R, ... Are connected in parallel to the secondary winding 121c as in this embodiment,
From the right side filament 5R, ... to the left side filament 5L,
Current flows to the ... Through the preheating transformer 121, and the operation of the fluorescent lamps FL1, ... becomes unstable. However, in the present embodiment, as described above, the common mode choke La.
Since 1, ... Are interposed, stable driving is ensured.

Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The backlight device 50 according to this embodiment is
It differs from that of the first embodiment in that it includes current detecting means 51, 52, abnormality determining means 53, and display means 54.

Here, the current detecting means (first current detecting means) 51 has one coil (first coil) 51a, and the coil is the secondary side terminal 3 of the lighting transformer 31.
1b ₁ and the left side filament 5L (between the lighting transformer 31 and the left side filament 5L, and between the preheating transformer 21 and the left side filament 5L). Further, the coil 51a is connected to a current detection device (first detection device) 51b, constitutes a CT (current transformer), and detects a current (that is, a preheating current or a lighting current) flowing in the left side filament 5L. Is configured to.

The other current detecting means (second current detecting means) 52 includes four coils (second coils) 52a,
It has 52b, 52c, and 52d. Then, these coils 52a, ... are secondary terminals 31b ₂ and the right filament 5R lighting transformer 31, between ... and transformer 31 during (for lighting and the right filament 5R, and the preheating transformer 21 And the right filament 5R), and these coils 52a, ... Are connected in series to form a current detection device (second detection device) 52e.
To CT to similarly configure CT. The number of coils 52a, ... Is the same as the number of right filaments 5R, and they are connected in series. In addition, each coil 52a,
Are connected by sequentially reversing the polarities of the coils (winding directions of the coils), and the directions of the induced currents induced in the coils 52a, ... Are opposite to each other. Therefore, when the currents (preheating current or lighting current) flowing through the right filaments 5R, ...
The induced currents induced in a, ... Cancel each other and the currents do not flow in the current detection device 52e. If they are not equal, only the current difference flows.

Further, the above-mentioned current detecting devices 51b, 52
The abnormality determining means 53 is connected to e, and the means 53
Is configured to convert the current signal from the current detection devices 51b and 52e into a voltage signal and compare the voltage signal with a reference voltage to determine whether the preheating current or the lighting current is abnormal. . Further, the abnormality display means 54 is connected to the abnormality determination means 53, and the abnormality determination means 53 is connected.
Predetermined display based on the signal from (high and low preheating current, etc.)
Is configured to display. The display means 54 in this embodiment includes a liquid crystal panel, an LED or the like capable of visually recognizing an abnormality, and a buzzer or the like capable of recognizing an abnormality by sound.

Next, the operation of this embodiment will be described.

During preheating, each left filament 5L,
When a preheating current flows through the coil, the current causes the coil 51a.
An induced current flows through the device, and the induced current is converted into a voltage by the current detecting means 51. Then, this voltage is compared with the reference voltage by the abnormality determination means 53, and when it is lower than the reference voltage, the display means 54 is driven to display the abnormality. Further, even when the coil 51a is turned on,
Since a current for lighting (discharge current) flows in the portion where the is arranged (between the secondary side terminal 31b ₁ and the left side filament 5L), an induced current flows in the coil 51a in the same manner as described above, and current detection is performed. The abnormality determination is performed by the means 51 and the abnormality determination means 53.

On the other hand, when a preheating current flows through each of the right side filaments 5R, ... During preheating, induced currents in opposite directions are induced in the coils 52a ,. When the preheating currents are equal and there is no variation between them, the induced currents cancel each other out, and the current detection means 52
No current flows through. In such a case, the current detection means 5
The voltage value output by 2 becomes zero, and the display means 54 displays that there is no abnormality. When the preheating currents are different from each other, a small amount of current flows through the current detecting means 52, the current is converted into a voltage and input to the abnormality determining means 53. Then, the discriminating means 53 drives the display means 54 to display that there is an abnormality. It should be noted that even when the light is turned on, the abnormality detection is performed by the same method as described above.

Next, the effect of this embodiment will be described.

According to this embodiment, the same effect as that of the first embodiment can be obtained, and it becomes possible to detect an abnormality at the time of preheating and at the time of lighting, and in the case of an abnormality, the drive of the apparatus is appropriately stopped. Measures can be taken and damage to the device can be prevented.

Further, since the left side filaments 5L, ... Are connected in series, the same current flows through each filament 5L ,. Therefore, each filament 5 is connected by one current detecting unit (first current detecting unit) 51.
The current flowing through L, ... Can be detected, and it is not necessary to provide the current detection means for the number of filaments, and the device can be simplified accordingly. Further, since the coils 52a, ... Detecting the currents flowing through the right side filaments 5R, ... Are arranged as described above, the respective filaments 5R ,. The current flowing through the device can be detected, and it is not necessary to provide as many current detecting means as the number of filaments, and the device is simplified accordingly. And
With such simplification of the device, the weight of the device can be reduced,
Maintenance can be facilitated and cost can be reduced.

[0043] Further, the coils 52a, ... are secondary terminals 31b ₂ and the right filament 5R lighting transformer 31, ... is disposed between, and the coil 51a
Is arranged between the secondary side terminal 31b ₁ of the lighting transformer 31 and the left filament 5L. Therefore,
Both the preheating current at the time of preheating and the lighting current at the time of lighting can be detected by the current detecting means 51, 52, and a dedicated detecting means for detecting the preheating current and a dedicated detecting means for detecting the lighting current are provided. There is no need to provide them separately. Therefore, also from that point, the device is simplified and the cost is reduced.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The same parts as those shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

Illumination device (illumination means) 10 according to the present embodiment.
0 is the backlight device 50 according to the third embodiment described above.
It is equipped with two (each backlight device is referred to by the code “50”).
A), “50B”, and “50C”), and the backlight devices 50A, 50B, and 50C respectively include a preheating unit 2, a lighting unit 3, a current detection unit (first current detection unit) 51, and a current detection. Means (second current detection means) 52,
Abnormality discrimination means 53 and two fluorescent lamps (hot cathode tubes) FL
1 and FL2 respectively. The preheating means 2, ... And the lighting means 3, ... Are connected to the lamp control means (control means) 101, and the lamp control means 101.
Are configured to drive the respective preheating means 2, ... And the lighting means 3, ..., And to appropriately turn on the fluorescent lamps FL1, FL2. .. are also connected to the control means 101, and the abnormality display means 54 is connected to the control means 101. When an abnormality occurs, the control means 101 drives the display means 54,
It is configured to display "the abnormality has occurred" and "the backlight device having the abnormality".

Next, the operation of this embodiment will be described.

Now, when the lamp control means 101 is activated, the control means sends a signal to each preheating means 2, ... To drive them, and preheats the six fluorescent lamps FL1 ,. After a lapse of a predetermined time, the lamp control means 101 stops driving the preheating means 2, ... And also the lighting means 3 ,.
To turn on the fluorescent lamps FL1 ,.

Then, for example, the backlight device 50A
If an abnormality such as disconnection occurs in the device 50A, the current detection means 51, 52 and the abnormality determination means 53 of the device 50A detect the abnormality, and the abnormality determination means 53 sends an abnormality signal to the lamp control means 101. Output. Then, the lamp control means 1
01 drives the display means 54 to display "the abnormality has occurred in the device 50A", stops the driving of only the device, and turns off the two fluorescent lamps FL1, FL2 of the device. It should be noted that although the brightness of the display becomes non-uniform due to the turning off of these fluorescent lamps FL1, FL2, the lamp control means 101 increases the brightness of the fluorescent lamps FL1, ... In the other devices 50B, 50C and is turned off. Device 50A
The two fluorescent lamps FL1 and FL2 are complemented.

Next, the effect of this embodiment will be described.

According to this embodiment, substantially the same effect as that of the above-mentioned third embodiment can be obtained. That is, in the case of abnormality, appropriate measures can be taken early and damage to the device can be prevented. In addition, it is possible to detect the preheating current and the lighting current flowing through all the fluorescent lamps with a current detecting device that is smaller than the number of fluorescent lamps, and it is possible to reduce the weight of the device.

On the other hand, according to this embodiment, it is possible to know the place where the abnormality has occurred (backlight device 50A, ...), so that the repair becomes easier. Further, when an abnormality occurs, the fluorescent lamps FL1, FL2, ...
Although the driving of the lighting device 100 is stopped, it is not necessary to stop the driving of the lighting device 100 itself, and the use can be continued.

Although the number of fluorescent lamps is six in the above embodiment, it is not limited to this and may be more. Further, although the number of the backlight devices is three in the present embodiment, it is not limited to this, and the number may be more.

Next, a fifth embodiment of the present invention will be described. The same parts as those shown in FIGS. 1 to 4 are designated by the same reference numerals and the description thereof will be omitted.

Illumination device (illumination means) 15 according to the present embodiment.
Reference numeral 0 indicates the backlight device 1 according to the first embodiment, to which the lamp control means 101 for driving the preheating means 2 and the lighting means 3 is connected. On the other hand, a liquid crystal panel (information display means) is provided near the backlight device 1.
The liquid crystal panel P is arranged so that a driving signal is input to display information and the backlight device 1 is illuminated to facilitate information recognition. In addition, the illumination device 150 includes the display signal detection unit 151.
And is configured to detect a change in the drive signal of the liquid crystal panel P. Then, the display signal detection means 151 outputs a predetermined signal to the lamp control means 101 when the change in the drive signal of the liquid crystal panel P is not detected for a certain period of time, and the lamp control means 101 lights up based on the signal. It is arranged to stop the driving of the means 3.

Next, the operation of this embodiment will be described.

Now, when the device according to this embodiment is driven,
The lamp control means 101 drives the preheating means 2 to drive the fluorescent lamp F.
Preheat L1, ... Then, when a predetermined time has passed,
The control means drives the lighting means 3 to light the fluorescent lamps FL1 ,. When a drive signal is sent to the liquid crystal panel P in this state, the panel displays various kinds of information, but the information is illuminated by the fluorescent lamps FL1, ...

By the way, when the driving signal to the panel P does not change when the operator stands up and the panel P continues to display the same information for a predetermined time, the display signal detection means 151 to the control means 101. To the lighting means 3 is turned off by the control means. Then, when the drive signal to the panel P changes, the control means re-drives the preheating means 2, but stops the preheating for a short time and directly drives the lighting means 3.

Next, the effect of this embodiment will be described.

According to this embodiment, when the display state of the liquid crystal panel P does not change for a certain period of time, the driving of the fluorescent lamps FL1, ... Is stopped, so that the life of the fluorescent lamps FL1 ,. There is no problem that is wasted. Also,
By minimizing the preheating time when the backlight device 1 is restarted, it is possible to shorten the time before re-driving, and the usability for the operator is improved.

In each of the above-mentioned embodiments, the voltage generators 20 and 30 perform the pulse width control, but it is not limited to this, and the input of the oscillation circuit is set to a predetermined value by self-oscillation. It may be controlled to. Further, in each of the above-described embodiments, the choke coil L is provided between the lighting transformers 31 and 131 and the right filament 5L, ....
1, ... was inserted, but need not be limited to this.
A capacitor may be interposed. Furthermore, although the backlight device 1 according to the first embodiment is used in the fifth embodiment described above, the invention is not limited to this, and the backlight device 10 according to the second embodiment and other backlight devices are used. You may do it.

[0061]

As described above, according to the present invention,
Since the plurality of hot cathode tubes are configured to be driven by one preheating means and one lighting means, the driving circuit and peripheral circuits are not complicated, the cost can be reduced accordingly, and the device can be simplified. Therefore, the reliability of the circuit is improved and the maintainability of the device is also improved.

When a plurality of first electrodes of the plurality of hot cathode tubes are connected in series to form a closed circuit together with the secondary winding of the preheating transformer, the one secondary winding is wound. The wires can preheat all the first electrodes. Therefore, the secondary winding of the preheating transformer can be reduced by that amount, and the weight of the device can be reduced.

By the way, if both the plurality of first electrodes and the plurality of second electrodes of the plurality of hot cathode tubes are wired in the same manner as the above-mentioned first electrode (that is, the plurality of second electrodes). (When the electrodes are connected in series and a closed circuit is formed by one secondary winding), only one hot cathode tube is turned on by driving the lighting means, and another hot cathode tube is turned on. May not light up. However, in the present invention, since the plurality of second electrodes are connected to the same number of secondary side windings to form closed circuits independently of each other, there is no problem as described above, and all hot cathodes are The tube can be reliably turned on.

Further, as described above, the first electrode is connected in series to form a closed circuit by one secondary winding, and the other second electrode is connected to the secondary winding. If the windings are connected in parallel to form a closed circuit, then only two secondary windings are needed to preheat the first and second electrodes. Therefore, in such a case, the number of secondary windings can be further reduced as compared with the above, and the weight of the device can be reduced. Also,
In this case, each second electrode is provided with a rectifying means to allow a current to flow from the preheating transformer to each of the second electrodes, and to prevent a current from the lighting transformer from flowing to the preheating transformer. By not allowing the flow, all hot cathode tubes can be reliably turned on.

Further, when choke coils are respectively provided between the lighting transformer and the plurality of second electrodes, it becomes possible to light all the hot cathode tubes simultaneously and stably.

On the other hand, first and second current detection means for detecting the currents flowing through the first and second electrodes, and abnormality determination means for performing abnormality determination based on the signals from these current detection means, When the above is provided, it is possible to take measures such as preheating of the hot cathode tube and stopping the lighting at the time of abnormality, and damage of the device can be prevented in advance. In this case, since the plurality of first electrodes are connected in series and the same current flows, only one first current detection unit (first coil) is required, which simplifies the device and reduces the cost. . In addition, when a plurality of second coils interposed in the plurality of second electrodes are connected in series and the polarities of the coils are sequentially reversed, one second detection device is used for all the second coils. Two electrodes can be monitored. Therefore, the device can be simplified and the cost can be reduced to the extent that only one second detection device is required. Further, if the current detection means is provided with an abnormality determination means to perform the abnormality determination, it is possible to take appropriate measures such as stopping the driving of the backlight device using the signal from the means. Further, by providing the abnormality display means and displaying the abnormality by the signal from the abnormality determination means, the operator can take appropriate measures early.
It is possible to prevent damage to the device.

Further, when a plurality of backlight devices are provided and an abnormality occurs in any of the backlight devices, the driving of the backlight device in which the abnormality occurs is stopped, and the hot cathode in the backlight device other than the device is stopped. By increasing the brightness of the tube and compensating for the loss of light, the use of the lighting means can be continued. Further, by driving the abnormality display means by the control means to specifically identify the backlight device in which the abnormality has occurred, the operator can easily know the location of the abnormality, and the repair becomes easier accordingly. .

On the other hand, a display signal detecting means for detecting a change in the drive signal of the information display means is provided, and when the display signal detecting means does not detect the change in the drive signal of the information display means for a predetermined time, the control means When the driving of the lighting means is stopped, there is no problem that the life of the hot cathode tube is reduced or energy is wasted. In addition, by minimizing the preheating time when the backlight device is restarted, it is possible to shorten the time before re-driving, and the usability for the operator is improved.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a structure of a backlight device according to a first embodiment.

FIG. 2 is a block diagram illustrating a structure of a backlight device according to a second embodiment.

FIG. 3 is a block diagram illustrating a structure of a backlight device according to a third embodiment.

FIG. 4 is a block diagram for explaining a structure of a lighting device according to a fourth embodiment.

FIG. 5 is a block diagram for explaining a structure of a lighting device according to a fifth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Backlight device 2 Preheating means 3 Lighting means 5L, ... Left side filament (1st electrode) 5R, ... Right side filament (2nd electrode) 10 Backlight apparatus 12 Preheating means 20 Lamp preheating voltage generation means (preheating power supply) 21 Preheating Transformers 21b, 21c, 21d, 21e, 21f Secondary Side Winding 30 Lamp Lighting Voltage Generating Means (Lighting Power Supply) 31 Lighting Transformer 50 Backlight Device 51 Current Detecting Means (First Current Detecting Means) 51a Coil (first coil) 51b Current detection device (first detection device) 52 Current detection means (second current detection means) 52a, 52b, 52c, 52d Coil (second coil) 52e Current detection device (second Detection device) 53 Abnormality determination means 54 Abnormality display means 100 Illumination device (illumination means) 101 Lamp control means ( 121) Preheating transformer 121b, 121c Secondary winding 150 Illuminator (illuminating means) 151 Display signal detecting means FL1, ... Fluorescent lamp (hot cathode tube) La1, La2, La3, La4 Common mode choke (rectifying means) ) L1, L2, L3, L4 choke coil P liquid crystal panel (information display means)

Claims (16)

[Claims] 1. A backlight device comprising a hot cathode tube, preheating means for preheating the hot cathode tube, and lighting means for applying a voltage to the hot cathode tube to turn on the hot cathode tube. A plurality of hot cathode tubes are provided, and the plurality of hot cathode tubes are preheated by one preheating means,
Further, the backlight device is characterized in that the plurality of hot cathode tubes are lit by one lighting means. 2. The hot cathode tube has a first electrode and a second electrode arranged so as to face each other, and the preheating means comprises a preheating power source and a preheating transformer, A current is passed through the first electrode and the second electrode to preheat these electrodes, and the lighting means includes a lighting power source and a lighting transformer, and the first electrode and the second electrode. The backlight device according to claim 1, wherein a voltage is applied between the hot cathode tube and the hot cathode tube to light the hot cathode tube. 3. The preheating transformer has one more secondary winding than the second electrode, and the plurality of first electrodes in the plurality of hot cathode tubes are connected in series to each other. Form a closed circuit with two secondary windings,
The backlight device according to claim 2, wherein the plurality of second electrodes of the plurality of hot cathode tubes independently form a closed circuit together with the secondary winding of the preheating transformer. . 4. The preheating transformer has two secondary windings, and the plurality of first electrodes of the plurality of hot cathode tubes are connected in series to close together with one secondary winding. Forming a circuit, the plurality of second electrodes in the plurality of hot cathode tubes are connected in parallel to another secondary winding, and form a closed circuit together with the secondary winding, and Rectifying means is provided on each second electrode to allow the flow of current from the preheating transformer to each of the second electrodes and not allow the flow of current from the lighting transformer to the preheating transformer. The backlight device according to claim 2, wherein 5. The backlight device according to claim 2, wherein choke coils are provided between the lighting transformer and the plurality of second electrodes, respectively. 6. A first current detecting means for detecting a current flowing through the first electrode, a second current detecting means for detecting a current flowing through the second electrode, and the first and second The backlight device according to any one of claims 2 to 5, further comprising: abnormality determination means for determining abnormality based on a signal from the current detection means. 7. The first current detecting means detects a current flowing between the lighting transformer and the preheating transformer and the first electrode, and the second current detecting means comprises: The backlight device according to claim 6, wherein a current flowing between the lighting transformer and the preheating transformer and the second electrode is detected. 8. The first current detecting means is one first
A coil and a first detection device connected to the coil, wherein the second current detection means has the same number of second coils as the second electrodes and a second detection device connected to these coils. And the first coil is interposed between the lighting transformer and the preheating transformer and the first electrode, and the plurality of second coils are provided in the lighting transformer and the preheating transformer. The second coil is connected between the second electrode and each of the second coils, and the second coils are connected in series and the polarities of the coils are sequentially reversed to form a closed circuit together with the second coil and the second detection device. The backlight device according to claim 7, wherein: 9. The backlight device according to claim 6, further comprising an abnormality display unit that displays an abnormality based on a signal from the abnormality determination unit. 10. The backlight device according to claim 2, wherein the preheating power source and the lighting power source control the current by self-oscillation. 11. The backlight device according to claim 2, wherein the preheating power source and the lighting power source control the current by pulse width control. 12. A backlight device according to any one of claims 6 to 9, and control means for driving each preheating means and lighting means of the plurality of backlight devices, and The control means receives a signal from each abnormality determination means of each backlight device, stops driving of the backlight device in which the abnormality has occurred, and at the same time, the hot cathode tube in the backlight device other than the backlight device in which the abnormality has occurred. The illumination means is characterized by increasing the brightness of the light source and complementing the decrease in the light amount. 13. The illumination unit according to claim 12, further comprising an abnormality display unit that is driven by the control unit to display an abnormality. 14. A backlight device according to claim 1, an information display means for displaying information by being illuminated by the backlight device, and a change of a drive signal of the information display means. A display signal detecting unit for detecting, and a control unit for driving the lighting unit of the backlight device, and when the display signal detecting unit does not detect a change in the drive signal of the information display unit for a predetermined time, The illumination means, wherein the control means stops driving the lighting means. 15. The illuminating means according to claim 12, wherein the preheating power source and the lighting power source control the current by self-oscillation. 16. The illuminating means according to claim 12, wherein the preheating power source and the lighting power source control the current by pulse width control.