JPH11162690A - Dimmer device for rare-gas discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dimmer device for a rare-gas discharge lamp enabling sure lighting without being much affected by the ambient temperature and enabling preset and desired optical output to be obtained at an early stage after lighting. SOLUTION: In this device, a switching means 21 is connected in series to the input side of a high-frequency high-voltage generating circuit 30 generating high-frequency high voltage while a rare-gas discharge lamp DL, having a pair of strip-like external electrodes spaced apart and disposed to form a first and second opening part on an outer circumferential surface of an enclosure having a luminous layer on its inner surface and having rare gas filled in its internal space, is connected to the output side thereof, and the rare-gas discharge lamp DL is disposed to stand opposite to an end face of a light-guiding plate having a display part, brightness of the display part is dimmed together with optical output of the rare-gas discharge lamp DL by giving a control signal with frequency set up to be not less than 40 Hz to the switching means 21 and by changing its on-duty ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimming device for a rare gas discharge lamp, and more particularly to a dimming device for a rare gas discharge lamp. The present invention relates to an improvement of a light control device that controls light output of a rare gas discharge lamp using a switching circuit and a high-frequency high-voltage generation circuit.

[0002]

2. Description of the Related Art In general, an instrument panel (hereinafter, referred to as an instrument panel) having a display section of various kinds of meters is arranged in a front portion of an automobile using an instrument cluster. Therefore, by looking at the instrument panel while the vehicle is running, for example, the running speed, the number of revolutions of the engine, and the like can be easily confirmed, and safe running can be ensured.

Conventionally, a lighting device and a fluorescent lamp capable of dimming have been applied to the illumination of this kind of instrument panel, for example, as shown in FIGS. FIG. 8 shows the lighting device. For example, the frequency is 43 KHz and the voltage is 12 KHz.
An inverter circuit H which generates a high-frequency high voltage of about 00 V and whose output waveform is substantially a sine wave, and an inverter circuit H
The inverter circuit H includes a switching transistor Q for controlling the supply of DC power to the power supply and a smoothing capacitor C. The inverter circuit H includes, for example, a primary coil TR.
a and TRb, an oscillation transformer TR having a secondary coil TRc and an exciting coil TRd, and primary coils TRa and TRb.
An oscillation capacitor C ₁ connected in parallel to the primary coil T
A choke coil CH connected between the midpoint of Ra and TRb and the switching transistor Q;
a, the first and second transistors Q connected to TRb
a, Qb and a resistor R connected between the choke coil CH and the bases of the first and second transistors Qa, Qb.
a, Rb, and the exciting coil TRd of the oscillation transformer TR includes first and second transistors Qa, Qb.
And the base of the first transistor Qa. And the switching transistor Q
A battery (not shown) is provided on the input side (terminals T1 and T2), and a cold cathode fluorescent lamp L is provided on the output side of the inverter circuit H.
Is connected.

This cathode fluorescent lamp L is applied to an instrument panel IP as an illumination light source as shown in FIGS.
The instrument panel IP is configured by a rectangular light guide plate GP having, for example, a display unit D for displaying the engine speed and the traveling speed on one surface and a rough surface formed on the other surface corresponding to the display unit D. The light guide plate GP is provided with a lighting device. This illuminating device is composed of, for example, a cold cathode fluorescent lamp L and a reflector R. The cold cathode fluorescent lamp L is disposed so as to face the end surface of the light guide plate GP. The light from the cold cathode fluorescent lamp L efficiently covers the outer periphery of the lamp L and the light guide plate GP.
It is arranged so that it may be incident. In this cold cathode fluorescent lamp L, for example, as shown in FIG. 11, a light emitting layer PH is formed on the inner surface of an envelope GB made of a glass bulb, and electrodes E and E are arranged at both ends of the envelope GB. In addition, an inert gas and mercury are sealed in the inner space of the envelope GB.

[0005]

The lighting device of this lighting device operates as follows. First, terminals T1,
A DC power source (battery) including, for example, an automobile generator is connected between T2 and a drive signal is applied to a terminal T3 at appropriate intervals. The drive signal is applied to the base of the switching transistor Q, and the switching transistor Q is turned on in connection with the application of the drive signal. During the ON period of the switching transistor Q,
The second transistors Qa and Qb are alternately turned on at predetermined timing by the cooperation of the resistors Ra and Rb, the primary coils TRa and TRb of the oscillation transformer TR, and the exciting coil TRd.
By turning N and OFF, the high frequency high voltage described above is generated in the secondary coil TRc of the oscillation transformer TR and applied to the electrodes E and E of the cold cathode fluorescent lamp L. Thereby, the cold cathode fluorescent lamp L is turned on, and the light of which density has been increased by the reflector R is incident on the light guide plate GP of the instrument panel IP. The light incident on the light guide plate GP travels while being totally reflected between the front part and the back part of the light guide plate GP, but diffusely reflects on the back part where the rough surface part is formed, and a part of the light is The light is emitted toward the front surface that has been formed (edge light effect). Accordingly, the display unit D is illuminated by the light emitted to the outside based on the edge light effect, and the instrument panel I is driven when the vehicle is running.
By looking at P, for example, the traveling speed, the number of revolutions of the engine, and the like can be easily confirmed, and it is possible to secure safe traveling.

[0006] In particular, the instrument panel I
When it is desired to adjust the illuminance of the display surface of P to an appropriate value, the brightness of the cold cathode fluorescent lamp L is changed by appropriately changing the interval (ON duty ratio) of the drive signal applied to the switching transistor Q. For example, 0.2 to 100%
Light can be arbitrarily adjusted in the range of (all light state). Therefore, the display surface of the instrument panel IP can always maintain the most visible state, so that the display contents can be accurately recognized.

However, an automobile may be used in a severe environment having an ambient temperature of, for example, -10.degree. C. or lower, or 40.degree. C. or higher. The brightness of L is extremely reduced. This is because the cold cathode fluorescent lamp L has a mercury resonance line (25
(3.7 nm) to excite the light emitting layer PH. That is, the vapor pressure of mercury varies depending on the ambient temperature, and when the ambient temperature is around 20 ° C., 6 to 10 × 10 ⁻³ m
mHg. The brightness of the cold cathode fluorescent lamp L becomes almost maximum when the vapor pressure of mercury is in the range of 6 to 10 × 10 ⁻³ mmHg, and the brightness decreases even if the mercury vapor pressure becomes higher or lower than this range. ,Get dark. In particular, for example, when the ambient temperature becomes extremely low, such as −10 ° C. or less, the brightness of the cold cathode fluorescent lamp L is extremely lowered, and the instrument panel IP cannot be adjusted to a desired brightness.
Not only can P not function as a light source for illumination, but also the cold cathode fluorescent lamp L is difficult to light due to the extremely low partial pressure ratio of mercury vapor pressure to inert gas partial pressure. .

When the ambient temperature is low, for example, about 0 ° C., the cold cathode fluorescent lamp L is relatively easily lit, but the light output at the beginning of lighting is small (dark), and the lighting causes the envelope to be darkened. Since the light output gradually increases with an increase in the mercury vapor pressure due to an increase in the temperature of GB, it takes about 5 to 20 minutes to reach the desired brightness, during which time it cannot be used properly. There is also a problem.

Therefore, conventionally, a heater is arranged near the cold cathode fluorescent lamp L, or a linear heater is spirally wound around the envelope GB of the cold cathode fluorescent lamp L. When the ambient temperature falls below a certain temperature, a lighting device configured to heat the cold cathode fluorescent lamp L by automatically energizing the heater in conjunction with the closing of the ignition switch has been put into practical use. I have.

However, according to this apparatus, the cold cathode fluorescent lamp L can be reliably turned on regardless of the ambient temperature, and a desired brightness can be obtained. Can be appropriately illuminated, but in the case of extremely low temperatures, a large-capacity heater must be used and a large amount of power must be supplied. When the cold cathode fluorescent lamp L reaches a predetermined temperature by heating the heater, the lighting device operates so that the heater becomes energized and the heater is energized at the same time when the engine is started. Due to the configuration, the problem that it takes a long time for the cold cathode fluorescent lamp L to reach a desired light output remains unsolved.

[0011] Therefore, an object of the present invention is to provide a rare gas discharge lamp which can be lit reliably without being affected by the ambient temperature and can obtain a desired light output set at an early stage after lighting. To provide a light control device.

[0012]

SUMMARY OF THE INVENTION Accordingly, in order to achieve the above-mentioned object, the present invention provides a high-frequency high-voltage generating circuit for generating a high-frequency high voltage, wherein a switching means is serially connected to an input side of the high-frequency high voltage generating circuit, A pair of strip-shaped external electrodes are arranged on an outer peripheral surface of an envelope having a light emitting layer on an inner surface and a rare gas sealed in an inner space so as to form first and second openings. And a switching means for controlling the switching means based on a control signal having a frequency set to 40 Hz or more, and an ON duty of the switching means.
The light output of the rare gas discharge lamp is dimmed by changing the ratio.

According to a second aspect of the present invention, there is provided a high-frequency high-voltage generating circuit for generating a high-frequency high voltage. A rare gas discharge lamp, in which a pair of band-shaped external electrodes are spaced apart from each other so as to form first and second openings, is connected to the outer peripheral surface of the envelope containing the rare gas. In addition, a rare gas discharge lamp is disposed so as to face an end face of a light guide plate having a display portion, and the switching means is controlled based on a control signal whose frequency is set to 40 Hz or higher, and its ON duty is controlled. The brightness of the display unit is dimmed together with the light output of the rare gas discharge lamp by changing the tee ratio.

Further, according to a third aspect of the present invention, the control signal of the switching means is a square wave, and the frequency of the control signal is four.
The fourth invention is characterized in that it is set to 0 Hz or more.
The control signal of the switching means is a square wave, and its frequency is 40 Hz to 5 kHz, preferably 50 Hz to 1 kHz.
Hz, the fifth invention is characterized in that:
An aperture portion having no light emitting layer is formed on an inner surface of the envelope substantially corresponding to the first opening of the rare gas discharge lamp. An aperture portion having no light-emitting layer is formed on the inner surface of the envelope substantially corresponding to the first opening portion, so that the rare gas discharge lamp faces the end face of the light guide plate such that the aperture portion faces the light guide plate. According to a seventh aspect of the present invention, the light guide plate is an instrument panel for a vehicle having a display unit on one surface.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a dimmer for a rare gas discharge lamp according to the present invention will be described with reference to FIGS. In FIG. 1, the dimmer includes a direct current source BA including, for example, a generator of an automobile, a DC-DC converter circuit 10 connected to the direct current source BA,
The switching circuit 20 connected to the output side of the C-DC converter circuit 10, the high-frequency high-voltage generating circuit (for example, an inverter circuit) 30 connected to the output side of the switching circuit 20, and the switching circuit 20 are controlled. And a rare gas discharge lamp DL connected to the output side of the high frequency high voltage generation circuit 30. The rare gas discharge lamp DL is incorporated in the instrument panel 50 as a light source for illumination. Have been.

The rare gas discharge lamp DL described above is configured, for example, as shown in FIG. In FIG. 1, reference numeral 1 denotes a straight tubular envelope which is hermetically sealed by a glass bulb, for example, and has a light emitting layer 2 made of a phosphor such as a rare earth phosphor or a halophosphate phosphor on the inner surface thereof. Is formed. In particular, the light emitting layer 2 is formed with an aperture 2a having a predetermined opening angle over substantially the entire length. The sealing structure of the envelope 1 is configured by sealing a disk-shaped sealing glass plate at the end of the glass bulb. For example, the glass bulb is simply heated without using the sealing glass plate. It is also possible to reduce the diameter while fusing it. still,
A rare gas such as xenon (Xe), krypton (Kr), neon (Ne), helium (He), which does not contain metal vapor such as mercury, is used alone or in a predetermined amount in the enclosed space of the envelope 1. It is enclosed.

A sheet structure 3 is wound around the outer peripheral surface of the envelope 1 so as to be in close contact therewith. This sheet structure 3
For example, an insulative translucent sheet 4 having a length substantially equal to the entire length of the envelope 1 and one surface of the translucent sheet 4 are spaced apart from each other by a predetermined distance. A pair of strip-shaped external electrodes 5 and 6 made of a bonded opaque metal member;
It is composed of terminals (not shown) led out from the ends of the external electrodes 5 and 6 and an adhesive layer (not shown) provided on one surface of the translucent sheet 4. In addition, the sheet structure 3
Of the external electrodes 5 and 6, a first opening 7 is formed between the other ends of the external electrodes 5 and 6, and a second opening 8 is formed between the other ends of the external electrodes 5 and 6. And the light emitting layer 2
Light is mainly emitted from the aperture 2a to the outside through the first opening 7. In the sheet structure 3, as the translucent sheet 4, for example, polyethylene terephthalate (PET) resin is suitable, but other resins such as polyester resin can also be used. Further, the external electrodes 5,
As 6, for example, an aluminum foil is preferable, but other metal members can be applied, and it is also possible to form by vapor deposition other than sticking.

The first and second external electrodes 5 and 6 described above
The opening angles θ ₁ and θ ₂ of the openings 7 and 8 are set to satisfy the relationship θ ₁ > θ ₂ , but the opening angle θ ₁ of the first opening 7 is 6
The range of 0 to 90 ° is that the opening angle θ ₂ of the second opening 8 is 5
About 5 ° is desirable. However, the opening angle θ ₁ of the first opening 7 can be set outside the above range depending on the application, and the second opening 8 is desirably narrow enough not to cause dielectric breakdown, for example, at least about 2 mm. It is recommended that the separation distance be maintained. The opening angle of the aperture 2a is set substantially equal to the opening angle θ1 of the _first opening 7.

The above-mentioned sheet structure 3 is mounted (wound) on the outer peripheral surface of the envelope 1 so that the external electrodes 5 and 6 are located between the envelope 1 and the translucent sheet 4. ) Has been. To mount the sheet structure 3 on the envelope 1, first, the sheet structure 3 is arranged in a deployed state on a stage having a flat upper surface. Next, the envelope 1 is disposed at one end 4a of the translucent sheet 4 in the sheet structure 3, and the envelope 1 is moved by a pair of driven rollers. The stage is moved in a predetermined direction after being set so as to be pressed against the stage. Then, the envelope 1 relatively rolls on the translucent sheet 4, and the sheet structure 3 is wound around the outer peripheral surface of the sheet 1 for mounting. In the sheet structure 3, the external electrodes 5, 6
Is adhered to the outer peripheral surface of the envelope 1 using an adhesive layer formed on the surface thereof, and the translucent sheet 4 is wound using the adhesive layer formed on one of the surfaces. It is bonded to the outer peripheral surface of the envelope 1 and each end 4a, 4b is
Are superimposed and adhered at the opening 8.

In the dimming device described above, the DC-DC converter circuit 10 has a function of outputting a substantially constant DC voltage even if the DC supply BA fluctuates. Series circuit of a coil 11 and switching means (for example, a field-effect transistor) 12 which are electrically connected, a series circuit of a diode 13, a resistor 14 and a resistor 15 connected in parallel to the switching means 12, and a resistor 14 And a capacitor 16 connected in parallel to a series circuit of a resistor 15 and a resistor 15. This DC-DC converter
The switching circuit 20 is connected to the output side of the switching circuit 10. The switching circuit 20 comprises, for example, a switching means (for example, a transistor) 21 and a base resistor 22 connected to the base of the switching means 21.
A high frequency high voltage generating circuit 30 for generating a high frequency high voltage of about 50 to 50 KHz and a voltage of about 1000 to 2500 V is connected.

The high-frequency high-voltage generating circuit 30 includes, for example, an oscillation transformer 31 having primary coils 31a and 31b, a secondary coil 31c and an exciting coil 31d, and a switching means 21 and a middle point between the primary coils 31a and 31b. The connected choke coil 32, the primary coil 31a,
31b, the first and second transistors 33, 3
4, an oscillation capacitor 35 connected in parallel to the primary coils 31a and 31b, and a resistor 36 connected between the input side of the switching means 21 and the first transistor 33. Excitation coil 31
d is connected to the bases of the first and second transistors 33 and 34. The secondary coil 31 of the oscillation transformer 31
The rare gas discharge lamp DL is connected to c.

In the above-mentioned light control device, a control signal generation circuit 40 is connected to the switching circuit 20, and the switching means 21 of the switching circuit 20 is turned on by a square wave control signal output from the control signal generation circuit 40.・ OFF control is performed. This control signal has a frequency of 40
Although it is set to be equal to or higher than 40 Hz, for example, when an extremely wide dimming range (for example, 0.2 to 100%) is required in instrument panel illumination, 40 to 100 Hz, preferably 50 to 100 Hz.
It is recommended to set it in the range of -75 Hz. If a very wide dimming range is not required, it is set to 40 Hz or more (100 KHz can be used). When the frequency of the control signal is set to 1 KHz, up to almost 2%,
When the frequency is set to 5 KHz, dimming can be performed up to approximately 9%. The above-described control signal generating circuit 40 includes, for example, an oscillator 41 for generating a sawtooth wave, a comparator 42, a control voltage source 43 which can be set to an arbitrary DC voltage, a resistor 44, and a switching means (for example, a transistor) 45. The collector of the switching means 45 is connected to the base of the switching means 21 via the base resistor 22. The switching means 21 is controlled based on the ON / OFF operation of the switching means 45 by the output signal from the comparator 42.

Further, the rare gas discharge lamp DL in the above-described light control device is arranged on the instrument panel 50 as an illumination light source, for example, as shown in FIGS. The instrument panel 50 is formed on, for example, a square light guide plate 51, a rare gas discharge lamp DL in which the first opening 7 is arranged to face an end face 51 a of the light guide plate 51, and a front surface 51 b of the light guide plate 51. The first and second display units 52 and 53 are provided, and a rough surface 54 formed on the back surface 51c of the light guide plate 51 corresponding to the first and second display units 52 and 53. In addition, the first,
The second display units 52 and 53 indicate, for example, the engine speed,
It is applied as a display unit of the traveling speed.

Next, the operation of the light control device thus configured will be described with reference to FIGS. First, the DC-DC converter circuit 10 is operated by a switch operation or the like.
Is connected to the control signal generator 17.
The switching means 12 is ON / OFF controlled at an appropriate timing by a signal from the controller 11, a predetermined voltage is generated in the coil 11, and a desired DC voltage is obtained based on the diode 13 and the capacitor 16. This output voltage (terminal voltage of the capacitor 16) is maintained at a substantially constant voltage by feeding back the distribution voltage by the resistors 14 and 15 to the control signal generation unit 17. For example, DC source B
When the voltage of A decreases, the ON / OFF timing of the switching means 12 is set short to increase the voltage generated in the coil 11, and conversely, when the voltage of the DC supply source BA increases, ON / OF of switching means 12
By setting the F timing to be long and reducing the voltage generated in the coil 11, the output voltage is controlled to be substantially constant. This DC output is input to the switching circuit 20. In this state, when a square wave control signal from the control signal generation circuit 40 is applied to the switching means 21 via the base resistor 22 (ON / OFF operation of the switching means 45 by the output signal of the comparator 42) When a control signal is applied in relation to
5A is ON / OFF controlled as shown in FIG. 5A, DC power is supplied to the high frequency high voltage generation circuit 30 only during the ON period (T _ON ), and the high frequency high voltage generation circuit 30 oscillates and outputs. A high-frequency high voltage as shown in FIG.

In the high frequency high voltage generating circuit 30,
Regarding the base of the second transistors 33 and 34, regardless of the ON / OFF control of the switching means 21, the driving signal is applied from the input side of the switching circuit 20 via the resistor 36. Immediately in response to the ON operation of 21, the high-frequency high-voltage generating circuit 30 starts the oscillating operation based on the cooperative action of the oscillating transformer 31, the first and second transistors 33 and 34, the oscillating capacitor 35 and the like. The oscillation operation is maintained during the period (T _ON ). Then, a high-frequency high voltage is output to the secondary coil 31c of the oscillation transformer 31, applied to the external electrodes 5 and 6 of the rare gas discharge lamp DL, and the rare gas discharge lamp DL is turned on. Since the rare gas discharge lamp DL does not contain a metal vapor such as mercury in the inner space of the envelope 1, the rare gas discharge lamp DL is turned on almost simultaneously with application of a high-frequency high voltage to the external electrodes 5 and 6, and almost turned on. At the same time, the set light amount is reached.

The light of the rare gas discharge lamp DL is transmitted to the aperture 2a.
And is released to the outside through the first opening 7 and
The light enters the light guide plate 51 of the instrument panel 50 from the end face 51a. The incident light is guided forward while being totally reflected by the inner surfaces of the front surface 51b and the back surface 51c of the light guide plate 51. When the totally reflected light reaches the rough surface portion 54 of the back surface 51c, the light is irregularly reflected and a part of the light is emitted to the outside from the front surface 51b. With this light, the first and second display units 5
2,53 are illuminated.

The light of the rare gas discharge lamp DL is dimmed by the ON duty ratio of a square wave control signal having a frequency output from the control signal generation circuit 40 of 40 Hz or more. In the control signal generation circuit 40, the oscillator 17 outputs the signal shown in FIG.
A voltage Vs of a sawtooth wave as shown in FIG. 6 is output, and an arbitrary DC voltage Vc is output from the control voltage source 43 as shown in FIG. 6B, and each output voltage is a comparator. 42. In the comparator 42, the voltage Vs of the sawtooth wave is compared with the voltage Vc, and the voltage Vs
Is output only in a range higher than the voltage Vc as shown in FIG. 6C. That is, the control voltage source 43
When the set voltage is V _C1, V _C2, V _C3, respectively, during the period in which the voltage Vs of the sawtooth wave exceeds these set voltage _{V C1, V C2, V C3} (T ON1, T ON2, T ON3), Control signals having different ON duty ratios are output. Figure (d)
FIG. 4E shows a square wave signal having an ON _duty ratio T _ON1 when the set voltage of the control voltage source 43 is V _C1 , and FIG.
The square wave signal having the _{ON duty} ratio T _ON2 is output when the set voltage of _No. 3 is V _C2 . Therefore, when a square wave signal set to an appropriate ON duty ratio is applied to the switching means 45 via the resistor 44, the switching means 45 turns ON only during this ON duty period, and the switching means 21 also operates. O only during that period
N operations are performed. Then, during the period in which ON operation _{(T ON1, T ON2, T} ON3), high-frequency high-voltage generating circuit 3
0 oscillates, and during the corresponding period, the rare gas discharge lamp DL is turned on at a predetermined dimming rate corresponding to the ON duty ratio.
FIG. 7 shows the relationship between the ON duty ratio of the control signal and the dimming rate.
(Solid line). Note that, in the same figure, the hatched portions represent the extinguished regions of the rare gas discharge lamp DL. Therefore, by changing the set voltage of the control voltage source 43 in the control signal generation circuit 40 in this manner, the ON duration of the control signal is changed.
Since the tee ratio can be set to an arbitrary value, the brightness of the rare gas discharge lamp DL can be adjusted in an arbitrary range excluding the extinguished region.

The above-mentioned rare gas discharge lamp DL is different from a discharge lamp using a hot cathode or a cold cathode, which is lit by one discharge path along the longitudinal direction of the envelope. (In a direction substantially perpendicular to the longitudinal direction of the envelope 1), an infinite number of discharge paths are formed, so that the light is emitted in a striped state, and the light emitting layer 2 is excited by a rare gas excitation line to emit light. In a normal lighting state, a striped discharge state cannot be visually observed. Accordingly, in such a dimmer, even if the frequency of the control signal applied from the control signal generation circuit 40 to the switching means 21 of the switching circuit 20 slightly changes, the high frequency high voltage generation circuit 30
Does not significantly affect the oscillating operation, the high-frequency high voltage applied to the external electrodes 5 and 6 is also substantially constant.

By the way, if the frequency of the control signal of the control signal generation circuit 40 is set to 40 Hz, preferably 50 Hz or more, even if the frequency is increased to about 50 KHz, for example, the control signal is in the range of 25 to 100%. In this case, the dimming can be performed, and it can be further increased to about 100 KHz. When the frequency is 1 KHz, dimming from 100% to about 2% is possible, and when it is 5 KHz, dimming from 100% to about 9% is possible. However, in the instrument panel lighting of a car, for example, 0.2 to
When an extremely wide dimming range is required, such as 100%, the frequency of the control signal of the control signal generation circuit 40 is 40
It is recommended to set the range to 100 Hz, preferably 50 to 75 Hz, and more preferably about 65 Hz. In such a frequency range, the above-described extremely wide range of dimming can be achieved. However, if the frequency is 5
When the duty ratio is less than 0 Hz, especially less than 40 Hz, as the ON duty ratio decreases, not only flickering occurs in the light emitted from the first opening 7 but also the discharge state becomes unstable and the stripes become unstable. As a result, a flickering state can be seen on the display surfaces of the first and second display sections 52 and 53 of the instrument panel 50. If the frequency exceeds 75 Hz, especially 100 Hz, the dimming range is narrowed, for example, as indicated by the dotted line in FIG. Therefore, it becomes difficult to apply to an application that requires an extremely wide dimming range in the instrument panel lighting of an automobile.

According to this embodiment, since the rare gas discharge lamp DL is applied as a light source for illumination of the instrument panel 50, even if the use environment of the automobile becomes extremely low, for example, -10 ° C. or less, it is not By applying a high-frequency high voltage to the external electrodes 5 and 6, it is possible to easily light up, not only to light up at a desired brightness, but also to start up to a preset light amount almost simultaneously with lighting. . Therefore, there is no need to dispose a heater near the cold cathode fluorescent lamp as in the prior art, and the apparatus configuration can be simplified.

In the rare gas discharge lamp DL, when the output voltage of the high-frequency high-voltage generating circuit 30 becomes low, the discharge state becomes unstable and the striped discharge state becomes visible. When the light is incident on the light guide plate 51 of the instrument panel 50, flicker caused by the striped discharge state is less likely to be felt when the first and second display units 52 and 53 are illuminated, and a good display is obtained. . However, when the frequency of the control signal of the control signal generation circuit 40 is less than 40 Hz, as the ON duty ratio decreases, the light emitted from the first opening 7 of the rare gas discharge lamp DL has a high frequency high voltage. The flicker caused by the shortened oscillation operation period of the generation circuit 30 occurs, and the display quality of the first and second display units 52 and 53 of the instrument panel 50 also deteriorates.

The control signal of the switching circuit 20 is
Since the frequency is set to 40 Hz or more, the brightness of the rare gas discharge lamp DL can be adjusted in a wide range by appropriately changing the ON duty ratio. In particular, if the frequency is set in the range of 40 to 100 Hz, preferably in the range of 50 to 75 Hz, and more preferably in the range of about 65 Hz, the instrument panel 50 is in the range of 0.2 to 100%.
Can be adjusted without deteriorating the display quality. However, depending on the required dimming range, the frequency can be appropriately set to 1 KHz, 5 KHz, or the like.

The rare gas discharge lamp DL applied to the instrument panel 50 has an aperture 2 on the end face 51a of the light guide plate 51.
a, since the first openings 7 are arranged so as to face each other, light emitted to the outside through the first openings 7 can be efficiently incident on the light guide plate 51. Therefore,
The first and second display units 52 and 53 of the instrument panel 50 can be appropriately illuminated.

Further, the bases of the first and second transistors 33 and 34 in the high-frequency high-voltage generating circuit 30 include:
Regardless of the ON / OFF operation of the switching circuit 20,
Since a drive signal is applied from the input side of the switching circuit 20 via the resistor 36, the O
The high-frequency high-voltage generating circuit 30 immediately starts oscillating based on the N operation. Therefore, even if the ON duty ratio decreases, the light can be appropriately adjusted.

In the present invention, the DC-DC converter circuit can be omitted depending on, for example, the voltage fluctuation of the DC supply source without being limited only to the above embodiment.
As the switching means of the switching circuit, a thyristor, a field effect transistor or the like can be used in addition to the transistor. The high-frequency high-voltage generation circuit can use various oscillation circuits, in addition to the single- and double-stone self-excited and separately-excited inverter circuits, and the switching elements thereof are transistors, thyristors, and field-effect types. Transistors and the like can also be used. The output waveform of the high-frequency high-voltage generating circuit may be a sine wave, a pulse wave, a rectangular wave, or the like. Further, in the rare gas discharge lamp, the light-emitting layer can be formed on the entire inner surface of the envelope by omitting the aperture portion, and a triangular shape, a semicircular shape, a rectangular shape, etc. Or a translucent sheet can be replaced with a heat-shrinkable resin tube. In particular, in the form of the external electrode, the “strip” means that the overall form is a strip, and not only those having a deformed portion on the side edge as described above, but also a portion other than the side edge. It is also assumed that holes or the like are present or meshes are included. Further, the light control device of the present invention can be applied to uses other than the instrument panel.

[0036]

As described above, according to the present invention, the switching means is connected to the input side of the high-frequency high-voltage generating circuit, and the rare gas discharge lamp is connected to the output side. ON by the control signal of
Since it is configured to be controlled to be OFF, a wide range of dimming is possible by changing the ON duty ratio of the control signal. In particular, when applied to instrument panel lighting, since the brightness and starting characteristics of the rare gas discharge lamp are not significantly affected by the ambient temperature, even when the ambient temperature of the vehicle is as low as -10 ° C. or less, for example. By applying a high-frequency high voltage to the external electrodes, not only the lighting can be easily performed, but also it is possible to start up to a preset light amount almost simultaneously with the lighting. Therefore, there is no need to dispose a heater near the cold cathode fluorescent lamp as in the prior art, and the apparatus configuration can be simplified.

When applied to instrument panel lighting, the frequency of the control signal applied to the switching means is 40 Hz.
As described above, by appropriately setting the ON duty ratio, light control can be performed at a level that does not impair display quality due to flicker over a wide range.

Further, when a rare gas discharge lamp is used as a light source for illuminating the instrument panel, even if the discharge state is unstable and a striped discharge is slightly visually observed in the rare gas discharge lamp alone, When the light is incident on the light guide plate of the instrument panel, flicker caused by a striped discharge state is less likely to be perceived when the display unit is illuminated, and a good display is obtained.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a light control device showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the rare gas discharge lamp shown in FIG.

FIG. 3 is a schematic front view showing a state where a rare gas discharge lamp is arranged on an instrument panel.

FIG. 4 is a sectional view of a main part of FIG. 3;

5A and 5B are explanatory diagrams of the operation of the high-frequency high-voltage generating circuit shown in FIG. 1, wherein FIG. 5A is an input current waveform diagram of the high-frequency high-voltage generating circuit, and FIG. The secondary voltage waveform diagram.

6A and 6B are explanatory diagrams of the operation of the control signal generation circuit shown in FIG. 1, wherein FIG. 6A shows an output waveform diagram of the oscillator, and FIG. 6B shows a relationship between the control voltage and the output voltage of the oscillator. Figure, FIG. (c) is ON du by the magnitude of the control voltage in FIG (b) - the square wave output at a drawing showing a state where the duty ratio is changed, FIG. (d) shows the control voltage V _C1 ( 7 (e) is a waveform diagram of a square wave output at the time of the control voltage V _C2 .

FIG. 7 is a diagram showing a relationship between an ON duty ratio and a dimming rate.

FIG. 8 is an electric circuit diagram of a conventional cold cathode fluorescent lamp lighting device.

FIG. 9 is a schematic front view showing a state where a cold cathode fluorescent lamp is arranged on the instrument panel.

FIG. 10 is a sectional view of a main part of FIG. 9;

FIG. 11 is a sectional view of a cold cathode fluorescent lamp.

[Explanation of symbols]

 BA battery DL rare gas discharge lamp 1 envelope 2 light emitting layer 2a aperture 3 sheet structure 4 translucent sheet 5, 6 external electrode 7 first opening 8 second opening 10 DC -DC converter 20 Switching circuit 21 Switching means 30 High frequency high voltage generating circuit 40 Control signal generating circuit 41 Oscillator 42 Comparator 43 Control voltage source 44 Resistance 45 Switching means 50 Instrument panel 51 Light guide plate 51a End face 51b Front face 51c Back face 52, 53 Display 54 Rough surface

Claims (7)

[Claims] 1. An envelope in which a switching means is serially provided on an input side of a high-frequency high-voltage generating circuit for generating a high-frequency high voltage, and an output side has a light-emitting layer on an inner surface and a rare gas enclosed in an inner space. A pair of strip-shaped external electrodes are connected to a rare gas discharge lamp arranged on the outer peripheral surface so as to be spaced apart from each other so that first and second openings are formed. Dimming the light output of the rare gas discharge lamp by controlling based on a control signal set to 40 Hz or more and changing the ON duty ratio of the rare gas discharge lamp. apparatus. 2. An envelope in which a switching means is serially connected to an input side of a high-frequency high-voltage generating circuit for generating a high-frequency high voltage, and an output side has a light-emitting layer on an inner surface and a rare gas sealed in an inner space. A rare gas discharge lamp, in which a pair of band-shaped external electrodes are spaced apart from each other so as to form first and second openings, is connected to the outer peripheral surface, and the rare gas discharge lamp is connected to the display unit. The switching means is controlled based on a control signal whose frequency is set to 40 Hz or more, and is turned on.
A dimming device for a rare gas discharge lamp, wherein the brightness of a display section is dimmed together with the light output of the rare gas discharge lamp by changing a duty ratio. 3. The dimming device for a rare gas discharge lamp according to claim 1, wherein the control signal of the switching means is a square wave, and the frequency is set to 40 Hz or more. 4. The control of a rare gas discharge lamp according to claim 2, wherein the control signal of the switching means is a square wave, and the frequency is set in a range of 40 Hz to 5 KHz, preferably 50 Hz to 1 KHz. Light device. 5. The rare gas discharge lamp according to claim 1, wherein an aperture portion having no light emitting layer is formed on an inner surface of the envelope substantially corresponding to the first opening of the rare gas discharge lamp. A dimmer for a rare gas discharge lamp as described in the above. 6. An aperture portion having no light-emitting layer formed on an inner surface of the envelope substantially corresponding to the first opening of the rare gas discharge lamp, and the rare gas discharge lamp is connected to an end face of a light guide plate. 3. The dimmer of a rare gas discharge lamp according to claim 2, wherein the apertures are arranged so as to face each other. 7. The dimmer of a rare gas discharge lamp according to claim 2, wherein the light guide plate is an instrument panel for a vehicle having a display unit on one surface.