JP2010015859A - Discharge lamp device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide discharge lamp device hardly affected by floating capacitance, solving a problem that unevenness is feared to be caused in discharge and light emission due to characteristics of the floating capacitance of a cold cathode discharge tube. <P>SOLUTION: The discharge lamp device includes a resonance circuit part 9 composed of an inductor 7 and a resonance capacitor 8 and a discharge lamp part 10 connected with the resonance circuit part 9. The discharge lamp part 10 is composed of a cold cathode discharge tube 11 and a capacitance cancel unit 13 structured of two diodes 12 arranged in an antiparallel, connected on both ends of the tube. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a discharge lamp device used in various electronic devices.

  Hereinafter, a conventional discharge lamp device will be described with reference to the drawings.

  FIG. 6 is a connection diagram of a conventional discharge lamp device, in which a cold cathode discharge tube 4 is connected to a resonance capacitor 3 connected in parallel to a secondary winding 2 of a transformer 1. Then, a high potential is applied to the cold cathode discharge tube 4 in the resonance frequency band mainly determined by the respective constants of the inductance value of the secondary winding 2 and the capacitance value of the resonance capacitor 3, Light is emitted. Here, in order to continue stable discharge and light emission in the cold cathode discharge tube 4 in each discharge device 5, supply of a high potential with small fluctuation is achieved by reducing the variation of the resonance frequency in each discharge device 5. Is needed.

For example, Patent Document 1 is known as prior art document information relating to the invention of this application.
JP 2005-176599 A

  In the conventional discharge lamp device 5, the basic structure of the cold cathode discharge tube (lamp) 4 is that a high frequency alternating current is applied to cause discharge light emission. The application of this high-frequency alternating current tends to have a stray capacitance Cs between the cold cathode discharge tube (lamp) 4 and the housing (not shown) or between the ground and the like. In the determination, the design is performed in consideration of the stray capacitance Cs in addition to the inductance value of the secondary winding 2 and the capacitance value of the resonance capacitor 3. That is, the stray capacitance Cs generated between the housing (not shown) of the set that houses the cold cathode discharge tube (lamp) 4 and the discharge lamp device 5 and the cold cathode discharge tube (lamp) 4 is resonant. The value of the capacitance component seen from the transformer 1 side is designed as (C + Cs), and it is necessary to supply a high potential by resonance after that. .

  However, since the stray capacitance Cs is a constant that depends on the positional relationship between the housing (not shown) and the cold cathode discharge tube (lamp) 4, the same transformer 1 and the same cold cathode discharge tube (lamp) 4 are used. Even if it is a combination, it is necessary to review the design every time the arrangement and positional relationship in the set are different. That is, the constant setting of the transformer 1 is required in spite of using the same cold cathode discharge tube (lamp) 4 in the same discharge lamp device 5 according to the change of the case for each set, Due to the characteristics of the stray capacitance Cs of each cold cathode discharge tube (lamp) 4, there is a problem that discharge and light emission may vary.

  Therefore, the present invention provides a discharge lamp device that is not easily affected by stray capacitance.

And to achieve this goal,
A resonant circuit unit comprising an inductor and a resonant capacitor;
A discharge lamp unit connected to the resonance circuit unit,
The discharge lamp section is composed of a cold cathode discharge tube and a capacity cancellation unit composed of two diodes arranged in reverse parallel and connected to both sides thereof.

  According to the present invention, the resonance capacitor and the stray capacitance can be handled as being separated on the circuit, so that the resonance frequency depends on the characteristics of the stray capacitance Cs of each cold cathode discharge tube 4. Thus, variations in discharge and light emission in the cold cathode discharge tubes 4 between sets and in different housings are less likely to occur, and the discharge lamp device 5 in another set can be applied by a transformer having the same constant setting.

  Hereinafter, a discharge lamp device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a connection diagram of a discharge lamp device according to an embodiment of the present invention, and a resonance circuit unit 9 including an inductor 7 and a resonance capacitor 8 that correspond to a secondary winding of a transformer 6, and a connection to the resonance circuit unit 9. The discharge lamp unit 10 is provided.

  The discharge lamp unit 10 includes a cold-cathode discharge tube 11 and a capacity canceling unit 13 configured by two diodes 12 connected in reverse parallel to each other.

  With the above configuration, a discharge lamp device having a circuit configuration having the resonance circuit unit 9 that is hardly affected by the fluctuation of the stray capacitance 15 generated between the cold cathode discharge tube 11 and the ground 14 can be obtained.

  Thus, in a set including one or a plurality of cold cathode discharge tubes 11, even if the value of the stray capacitance 15 included in each cold cathode discharge tube 11 is different, the cold cathode discharge tubes for each set. 11 discharge and light emission can be made less likely to vary. That is, it is possible to make it difficult to cause variations in the discharge and light emission of the cold cathode discharge tube caused by the variation between the sets of the stray capacitance 15 caused by different housings (not shown).

  In addition, since the resonance circuit unit 9 is not easily affected by the value of the stray capacitance 15, even if the cold cathode discharge tube 11 is the same product on different sets where the conditions of the stray capacitance 15 change, The constant of the inductor 7 and the constant of the resonant capacitor 8 can be applied without the need for a design change in the same state, and the design can be simplified.

The above configuration can be explained by simplifying the relationship of the circuit state in the resonance frequency band by the equivalent circuit shown in FIG. Here, the resonance circuit unit 9 including the inductor 7 and the resonance capacitor 8 is the same as the connection diagram of the discharge lamp device shown in FIG. On the other hand, when a forward bias is applied, the diode 12 can be substituted for the capacitor 16 shown in FIG. The capacitance value Cd of the capacitor 16 is Cd << Cs, where C is the capacitance value of the resonant capacitor 8 and Cs is the capacitance value of the stray capacitance 15.
Cd << C
The relationship is established.

Here, even if C and Cs are values close to each other, since Cs and Cd are connected in series, the discharge lamp unit 10 including the capacitance value Cd of the capacitor 16 as viewed from the resonance circuit unit 9 is used. The capacitance value C1 is C1 << C
This relationship is established.

  That is, the change in the capacitance value Cs of the stray capacitance 15 is a factor that causes the capacitance value C1 of the discharge lamp unit 10 shown in FIG. 2B to fluctuate, but the C1 is much higher than the capacitance value C of the resonance capacitor 8. Since the value is small, the influence of C1 on the resonance frequency by the inductor 7 and the resonance capacitor 8 is very small.

  Actually, the capacitor 16 has a resistance Dr in the forward bias direction in parallel with each other, and therefore there is a portion that does not completely satisfy the above relationship, but the relationship between C, Cd, and Cs is generally maintained. From the relationship between the capacitance values, C and Cs are separated from each other, and power can be supplied from the resonance circuit section 9 to the discharge lamp section 10 through the forward bias resistor Dr.

  Further, the capacitance value Cd of the capacitor 16 shown in FIG. 2A corresponding to the diode 12 shown in FIG. 1 is also a factor that causes the capacitance value C1 of the discharge lamp unit 10 shown in FIG. Similar to the above case, the influence of C1 on the resonance frequency is very small.

  Therefore, since the resonance frequency of the resonance circuit unit 9 shown in FIG. 1 does not change, power can be supplied to the cold cathode discharge tube 11 without changing the resonance voltage at a specific frequency, and variations in the light emission state can be reduced. Is.

  Alternatively, when a more rigorous lighting state setting is required, the capacitance value Cs of the stray capacitance 15 and the capacitance value Cd of the capacitor 16 shown in FIG. By determining circuit constants based on the inflowing leakage current, it is possible to obtain lighting conditions that are closer to the optimum and to suppress variations in the light emission state. Actually, since the capacitance value Cd can be specified almost accurately depending on the product number to be used, by assuming the value of the capacitance value Cs, it is possible to obtain lighting conditions that are close to optimum on many sets under one design condition. Is.

  That is, even when the housing (not shown) in which the discharge lamp unit 10 is housed and installed is on different sets, it is possible to obtain lighting conditions that are close to optimal with the same circuit constant.

  Here, the potential distribution in the cold cathode discharge tube 11 gradually decreases as the distance from the transformer 6 side increases to the opposite side of the transformer 6. Therefore, the withstand voltage of the capacitance canceling unit 13 connected to the low potential side on the ground 14 side with respect to the cold cathode discharge tube 11 is the capacitance connected to the high potential side on the transformer 6 side with respect to the cold cathode discharge tube 11. It may be smaller than the withstand voltage of the cancel unit 13. Thereby, the capacity cancellation unit 13 connected to the low potential side can be reduced in size and cost.

  Further, the potential distribution in the cold cathode discharge tube 11 gradually decreases as it moves away from the transformer 6 side to the opposite side of the transformer 6, so that the stray capacitance 15 generated between the cold cathode discharge tube 11 and the ground 14. Also, the magnitude of becomes smaller from the transformer 6 side to the opposite side of the transformer 6 and toward the low potential side. Therefore, since the degree of influence on the resonance circuit unit 9 is reduced, the capacitance canceling unit 13 connected to the low potential side that suppresses the degree of influence may be removed.

  Thereby, the fluctuation | variation of the resonant frequency by the inductor 7 and the resonant capacitor 8 can be suppressed with few components.

  Here, the discharge lamp unit 10 having one cold cathode discharge tube 11 has been described. However, a plurality of cold cathode discharge tubes 11 are connected to both sides of each cold cathode discharge tube 11 or a high potential side. A discharge lamp unit comprising the capacity canceling unit 13 may be used.

  In this case, as described above, even when the value of the stray capacitance 15 included in each cold cathode discharge tube 11 is different, the variation of the resonance frequency can be suppressed. Similarly, variations in the discharge and light emission of the cold cathode discharge tube 11 between sets can be made difficult to occur.

(Embodiment 2)
FIG. 3 is a connection diagram of the discharge lamp device according to the second embodiment of the present invention. The resonance circuit unit 9 includes an inductor 7 and a resonance capacitor 8 corresponding to the secondary winding of the transformer 6, and the resonance circuit unit 9. And a parallel discharge lamp unit 10 connected via a shunt circuit 17.

  The discharge lamp unit 10 includes a cold-cathode discharge tube 11 and a capacity canceling unit 13 configured by two diodes 12 connected in reverse parallel to each other.

  With this configuration, in addition to the effect of suppressing the variation in the lighting state of the cold cathode discharge tubes 11 between sets by the capacity canceling unit 13, the plurality of cold cathode discharge tubes 11 in each set by the balancer that is the shunt circuit 17 are arranged. A very stable lighting state can be obtained by a synergistic effect with the effect of averaging the lighting state.

  Here, the shunt circuit 17 is composed of a capacitor (not shown) and an inductor (not shown). However, since the elements in the shunt circuit 17 are not variable values such as the stray capacitance 15, the shunt circuit 17 An arbitrary resonance voltage can be obtained by determining the constant of the resonance circuit unit 9 in consideration of the constant. Alternatively, the individual circuit in the shunt circuit 17 is a capacitor having a series component for connecting the resonant circuit unit 9 and the discharge lamp unit 10, and more than the series capacitance component of the discharge lamp unit 10 with respect to the shunt circuit 17. By making it small, the influence which the shunt circuit 17 and the discharge lamp part 10 have with respect to the resonant frequency of the resonant circuit part 9 can be made smaller.

That is, as shown in FIG. 4, when the capacitance value of the shunt circuit 17 is Cx and the capacitance value of the discharge lamp unit 10 is Cy, the combined value of Cx and Cy is Cx · Cy / (Cx + Cy).
Where Cx <Cy
Then, Cx · Cy / (Cx + Cy) <Cy
As described above, the capacitance value C of the resonant capacitor 8 is C >> Cy.
And
Cx · Cy / (Cx + Cy)
In this part, the influence on the resonance frequency of the resonance circuit unit 9 can be further reduced.

(Embodiment 3)
FIG. 5 is a connection diagram of the discharge lamp device according to the third embodiment of the present invention. The resonant circuit section 9 is composed of an inductor 7 and a resonant capacitor 8 that correspond to the secondary winding of the transformer 6, and the resonant circuit section 9. And a plurality of discharge lamp sections 19 connected via a shunt circuit 17 and a first capacity canceling unit 18 constituted by two diodes 12 arranged in antiparallel.

  The discharge lamp unit 19 is composed of a cold cathode discharge tube 11 and two diodes 12 connected in reverse parallel to the cold cathode discharge tube 11 on the side opposite to the direction of the transformer 6 with respect to the cold cathode discharge tube 11. 2 capacity cancellation units 13.

  With this configuration, the capacity component of the discharge lamp unit 19 including the capacity component of the shunt circuit 17 is transferred to the resonance circuit unit 9 by the first capacity canceling unit 18 in the same manner as described above. It can be in a state that does not affect. In particular, in this configuration, both the shunt circuit 17 and the discharge lamp unit 19 are located on the opposite side of the resonance circuit unit 9 with respect to the first capacity canceling unit 18, and the shunt circuit 17 and the discharge lamp unit 19 are the resonant circuit. The influence on the fluctuation of the resonance frequency of the part 9 can be made very small. Therefore, the resonance frequency of the resonance circuit unit 9 can be determined by the constants of the inductor 7 and the resonance capacitor 8 even when the shunt circuit 17 is involved. Of course, the resonant circuit unit 9 can supply a stable resonance voltage to the cold cathode discharge tube 11 at a stable resonance frequency because it is hardly affected by the stray capacitance 15 of the cold cathode discharge tube 11.

  From the above, in the second embodiment and the third embodiment, in addition to the effect of suppressing the variation in the lighting state of the cold cathode discharge tube 11 between sets, a plurality of cooling by the balancer which is the shunt circuit 17 is performed. A very stable lighting state can be obtained by a synergistic effect with the effect of averaging the lighting state of the cathode discharge tube 11.

  Also, here, a control voltage dividing capacitor 20 connected in series to the resonant capacitor 8 and a series resistor 21 are provided for the forward-connected diodes 12 in the capacitance canceling unit 13 on the low potential side. One terminal of the control circuit 23 is connected to the connection point between the resonant capacitor 8 and the control voltage dividing capacitor 20, and the other terminal of the control circuit 23 is connected to the connection point between the diode 12 and the resistor 21. . This further stabilizes the lamp current in the cold cathode discharge tube 11 and compensates for stabilization when the resonance voltage obtained at the specified resonance frequency changes as the resonance frequency varies. In addition to the stabilization of the lighting state by the capacity cancellation unit 13 described above, further stabilization is possible. Further, since the fluctuation level is suppressed to be small by the capacity cancellation unit 13, sufficient stabilization can be achieved even with control having a stabilization function in a relatively small region.

  As an example of the above-mentioned stabilization compensation, as shown in FIG. 5, the capacitance canceling unit 13 on the low potential side of the cold cathode discharge tube 11 is connected to the cold cathode discharge tube 11 by connecting a resistor 21 to the ground side. It is used to detect the flowing current. In this case, since the non-detection current is a portion directly connected to the low potential side of the cold cathode discharge tube 11, the grounding portion EL of the capacitance canceling unit 13 on the low potential side of the cold cathode discharge tube 11 and the inductor of the transformer 6 are used. The current can be detected in a state where it is difficult to be affected by the distortion of the current waveform due to the impedance between grounds (not shown) generated between the grounding part ET and the grounding part 7. This enables accurate current detection. In particular, when the cold cathode discharge tube 11 is large and has a large current value and accuracy of current detection is required, it is effective in that accurate current detection is possible.

  Further, the resistor 21 for current detection may correspond to each cold cathode discharge tube 11, but the resistor 21 is made to function for one cold cathode discharge tube 11. It doesn't matter.

  As described above, by using the diode 12 in the capacitance canceling unit 13, it is possible to prevent the stray capacitance on the circuit, particularly in the lamp, from affecting the resonance frequency in a state where a large current flows through the lamp. Is.

  Here, the discharge tube in the discharge lamp unit 19 has been described by taking a cold cathode discharge tube as an example, but can be applied to various discharge tubes such as a hot cathode discharge tube and an external cathode discharge tube.

  The discharge lamp device according to the present invention has the effect of being able to ensure a stable lighting state that is hardly affected by the characteristic difference of each cold cathode discharge tube and the distribution capacity related thereto, and is useful in various electronic devices. is there.

Connection diagram of discharge lamp apparatus in first embodiment of the present invention (A) 1st circuit diagram of the discharge lamp apparatus in 1st embodiment of this invention, (b) 2nd circuit diagram of the discharge lamp apparatus in 1st embodiment of this invention. Connection diagram of discharge lamp device in second embodiment of the present invention The circuit diagram of the discharge lamp apparatus in 2nd embodiment of this invention The circuit diagram of the discharge lamp apparatus in 3rd embodiment of this invention Circuit diagram of conventional discharge lamp device

Explanation of symbols

6 Transformer 7 Inductor 8 Resonant capacitor 9 Resonant circuit unit 10 Discharge lamp unit 11 Cold cathode discharge tube 12 Diode 13 Capacitance cancellation unit 14 Ground 15 Floating capacitance

Claims (6)

A resonant circuit unit comprising an inductor and a resonant capacitor;
A discharge lamp unit connected to the resonance circuit unit,
The discharge lamp unit is a discharge lamp device comprising a cold cathode discharge tube and a capacity cancellation unit composed of two diodes arranged in reverse parallel and connected to both sides thereof. The withstand voltage of the first capacity cancellation unit connected to the high potential side with respect to the cold cathode discharge tube is:
The discharge lamp device according to claim 1, wherein the withstand voltage of the second capacity canceling unit connected to the low potential side is larger than the withstand voltage. A resonant circuit unit comprising an inductor and a resonant capacitor;
A discharge lamp unit connected to the resonance circuit unit,
The discharge lamp unit is a discharge lamp device comprising a cold cathode discharge tube and a capacity cancellation unit composed of two diodes arranged in reverse parallel connected to the high potential side. A resonant circuit unit comprising an inductor and a resonant capacitor;
A plurality of discharge lamp parts connected to the resonant circuit part via a shunt circuit,
The discharge lamp unit is a discharge lamp device comprising a cold cathode discharge tube and a capacity cancellation unit composed of two diodes arranged in reverse parallel and connected to both sides thereof. A resonant circuit unit comprising an inductor and a resonant capacitor;
The resonance circuit unit includes a first capacity cancellation unit configured by two diodes arranged in antiparallel and a plurality of discharge lamp units connected via a shunt circuit,
The discharge lamp unit is a discharge lamp device including a cold cathode discharge tube and a second capacity cancellation unit configured by two diodes arranged in reverse parallel and connected to a low potential side thereof. A controlled voltage dividing capacitor connected in series to the resonant capacitor;
Provide a resistor in series with the forward-connected diode of the low-potential side capacitance cancellation unit,
Connecting one terminal of a control circuit to a connection point between the resonant capacitor and the control voltage dividing capacitor;
The discharge lamp device according to any one of claims 1, 2, 4, and 5, wherein the other terminal of the control circuit is connected to a connection point between the diode and the resistor.

Images