JPH04324287A - Luminous radiation electron tube lighting device - Google Patents

Abstract

PURPOSE:To suppress a change of color temperature and shortness of a life generated by changing tube voltage between a filament and an accelerating electrode. CONSTITUTION:A luminous radiation electron tube 1 is provided with a bulb 1a sealed with luminous radiation gas excited by an impact by an accelerating electron to emit light and a pair of filaments 1b provided in the bulb 1a. Accelerating voltage is applied between both the filaments 1b by a lighting power feed source 2, and an electron emitted from the one filament 1b, is attracted to the other filament 1b and accelerated. In a filament heating circuit 3, power fed to the filaments 1b is adjusted in accordance with a high/low level of tube voltage between the filaments 1b so as to hold the tube voltage to almost a fixed value.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is characterized in that a filament serving as a cathode and an accelerating electrode that accelerates electrons emitted from the filament are filled with a light-emitting gas and a rare gas that emit light when excited by the collision of accelerated electrons. The present invention relates to a light-emitting electron tube lighting device for lighting a light-emitting electron tube disposed in a light-emitting bulb.

0002

2. Description of the Related Art Conventionally, a light emitting electron tube 1 having a structure as shown in FIG.
130364). The light-emitting electron tube 1 includes a filament 1b that serves as a thermionic-emitting cathode, and an accelerating electrode 1c that accelerates electrons emitted from the filament 1b, in a bulb 1 made of a transparent material such as glass. It has a configuration in which the two are placed opposite each other. The interior of the bulb 1a is filled with a mixed gas of a light emitting gas such as mercury vapor and neon, which is a rare gas, at a pressure of about several milliTorr, resulting in a low vacuum. Further, the inner peripheral surface of the bulb 1a is coated with a phosphor (not shown) that converts ultraviolet rays into visible light.

In order to light up the light emitting electron tube 1, electrons are emitted by supplying power between both ends of the filament 1b, and the filament 1b and the accelerating electrode are connected so that the filament 1b becomes the negative electrode and the accelerating electrode 1c becomes the positive electrode. Electrons are accelerated by applying an accelerating voltage between the electrode and the electrode 1c. Accelerated electrons ionize or excite gas atoms and molecules sealed in the bulb 1a by colliding with them, and if the light emitting gas is mercury vapor, mainly ultraviolet rays are emitted. become. This ultraviolet light is converted into visible light by the phosphor, and visible light is emitted from the bulb 1a. This light emitting electron tube 1
has the advantages of small size, light weight, low cost, and high efficiency.
Demand is expected to increase in the future.

By the way, as a light-emitting electron tube lighting device, the configuration shown in FIG. 14 has been considered. This light emitting electron tube lighting device has a DC power source E. A series circuit of a switching element Qa and an inductor L is connected between both ends of the DC power supply E. Further, one end of the parallel circuit of the switching element Qb and the capacitor Cb is connected to the connection point between the switching element Qa and one end of the inductor L via the diode D, and the other end of the parallel circuit is connected to the filament of the light-emitting electron tube 1. It is connected to the other end of the inductor L via 1b. Further, the acceleration electrode 1c of the light emitting electron tube 1 is connected to the connection point between the diode D and the switching element Qb. Each switching element Qa, Qb is controlled on/off by a control circuit S. The DC power source E is obtained by rectifying the AC power source AC (for example, obtained by stepping down a commercial AC power source) with a bridge rectifier RE made up of a diode bridge, and then smoothing it with a capacitor Ca.

In this light-emitting electron tube lighting device, before lighting the light-emitting electron tube 1 by applying an accelerating voltage between the filament 1b and the accelerating electrode 1c, the filament 1b is first preheated. That is, the switching element Qa is turned on and off while the switching element Qb is turned on. During the period when the switching element Qa is on, the current from the DC power supply E flows through the inductor L, and energy is accumulated in the inductor L, and during the period when the switching element Qb is off, the energy accumulated in the inductor L causes the current to flow through the inductor L. , a current flows through the path of diode D, switching element Qb, and filament 1b, and the filament 1b is heated. After the filament 1b is heated to a temperature at which the light-emitting electron tube 1 can be lit by such preheating, the switching element Qa is controlled to be turned on and off while the switching element Qb is turned off. At this time, the AC component of the current passing through the diode D flows to the filament 1b through the capacitor Cb, so the filament 1b is constantly heated, and the DC component causes an acceleration voltage to be applied between the filament 1b and the acceleration electrode 1c. Since the voltage is applied, the light-emitting electron tube 1 lights up.

As is clear from the above configuration, when the light emitting electron tube 1 is lit, if the on-duty and switching frequency for turning on and off the switching element Qa are changed by the control circuit S, the light emission can be stopped. electron tube 1
Since the amount of energy supplied to the light emitting electron tube 1 changes, the light output from the light emitting electron tube 1 can be changed to perform dimming.

However, in the above configuration, by reducing the on-duty of the switching element Qa, the filament 1b of the light-emitting electron tube 1 and the accelerating electrode 1c are
When the lamp current flowing between the filament 1b and the light output is reduced, the heating current flowing through the filament 1b also decreases, and the amount of electrons emitted decreases. As a result, a problem arises in that the lighting state cannot be maintained. That is, Figure 1
The light-emitting electron tube lighting device shown in No. 4 has a problem in that the light output is limited on the low output side and the light output cannot be dimmed in the range of 0 to 100%.

[0008] In order to solve this problem, it is conceivable to heat the filament 1b to an appropriate temperature even when the optical output is low. For example, a configuration as shown in FIG. 15 can be considered. Here, an inverter section I is provided as an alternating power generation section that converts a DC power source E into alternating power, and a part of the output of the inverter section I is configured to be used for heating the filament 1b. That is, the inverter section I is a power MOS connected between both ends of the DC power source E.
A pair of switching elements Qc and Qd consisting of FETs etc.
A series circuit of a capacitor Cc and a primary winding of a heating transformer Ta is connected between both ends of the switching element Qd. Further, a series circuit of a capacitor Cd and a primary winding of the output transformer Tb is connected in parallel to the primary winding of the heating transformer Ta. The alternating current output from the secondary winding of the output transformer Tb is rectified by the bridge rectifier REa via the inductor La, and then connected to the capacitor C.
smoothed by e. That is, the bridge rectifier R
A rectifying and smoothing section J is constituted by Ea and the capacitor Ce. The voltage across the capacitor Ce is the accelerating voltage,
A voltage is applied between one end of the filament 1b and the acceleration electrode 1c. Both ends of the secondary winding of the heating transformer Ta are connected to the filament 1b via a capacitor Cf, so that the filament 1b is heated by alternating current induced in the secondary winding. A switching element Qe is connected between the other end of the filament 1b and the acceleration electrode 1c. The switching elements Qc, Qd, and Qe are controlled to be turned on and off by the control circuit S, and the switching elements Qc and Qd are controlled to be alternately and selectively turned on.

In this configuration, the filament 1 is
To perform the preheating of step b, with switching element Qe turned on, switching elements Qc and Qd are alternately and selectively turned on. This operation causes the switching element Q
When c is on, capacitors Cc and Cd are charged, and when switching element Qd is on, capacitors Cc and C
Since d is discharged, alternating current is obtained in the secondary windings of the heating transformer Ta and the output transformer Tb, respectively. At this time, since the switching element Qe is on, a direct current flows through the filament 1b due to the output of the rectifying and smoothing section J, and at the same time, an alternating current flows through the filament 1b due to the output of the secondary winding of the heating transformer Ta.

When the filament 1b is heated to a temperature sufficient to light the light emitting electron tube 1, the switching elements Qe and Q are turned off with the switching element Qe turned off.
ON/OFF control of only d. At this time, no direct current flows through the filament 1b, and an accelerating voltage is applied between the filament 1b and the accelerating electrode 1c by the output of the rectifying and smoothing section J, and the light-emitting electron tube 1 is turned on. At this time, since a heating current flows through the filament 1b due to the alternating current induced in the secondary winding of the heating transformer Ta, the filament 1b is constantly heated.

In the configuration of FIG. 15, the switching element Qc
, if the switching frequency of Qd is changed, the frequency of the alternating current induced in the secondary winding of the output transformer Tb changes, so the impedance of the inductor La changes and the filament 1b of the light-emitting electron tube 1 and the accelerating electrode 1c can be changed. In other words, the light output of the light emitting electron tube 1 can be adjusted to achieve dimming. Furthermore, even if the switching frequencies of the switching elements Qc and Qd are changed, the power supplied to the filament 1b by the heating transformer Ta does not change much, so the heating current to the filament 1b can be kept almost constant. . As a result, if the heating current is set so that a sufficient amount of electrons are emitted from the filament 1b, a sufficient amount of electrons can be emitted from the filament 1b even if the optical output becomes low. Therefore, the optical output can be controlled within the range of 0 to 100%.

0012

[Problems to be Solved by the Invention] With the above configuration, it is possible to adjust the light output so that it is in the range of 0 to 100%, but in a specific region where the tube current is relatively low, the rare gas A problem arises in that light emission occurs. For example, when the rare gas is neon, it emits red light. Let's consider this phenomenon.

When the voltage applied to both ends of the filament 1b is kept constant, the optical output is approximately proportional to the tube current, as shown in FIG. In addition, the tube voltage is shown in Figure 1.
7, it changes depending on the tube current. That is,
The tube voltage is almost constant in a region where the tube current is relatively large, but becomes high in a region where the tube current is around 30%. On the other hand, there is a relationship between the tube voltage and the color temperature of the light output as shown in FIG. 18, and as the tube voltage increases, the color temperature tends to decrease. Therefore, red light emission occurs in specific regions where the tube current is relatively low.

[0014] In addition to the problem that the color temperature decreases as the tube voltage increases, the following problems occur. That is, the main cause of the increase in tube voltage is due to the increase in cathode drop, and when the tube voltage increases, the strength of the electric field around the filament 1b is greater than when the tube voltage is low. Therefore, the ions of the light emitting gas are accelerated with a large force and collide with the filament 1b. As a result, a sputtering phenomenon occurs with the filament 1b as a target, causing the problem that the electron emitting material attached to the filament 1b is scattered. When the electron emitting material scatters, the life of the bulb 1a is shortened, and the inner circumferential surface of the bulb 1a becomes black, resulting in a decrease in luminance.

[0015] The tube voltage varies not only when dimming is performed, but also due to ambient temperature and changes over time, causing the above-mentioned problems. The present invention aims to solve the above-mentioned problem, which occurs when the tube voltage between the filament and the accelerating electrode changes due to the amount of dimming, ambient temperature, changes over time, etc. when lighting a light-emitting electron tube. The present invention aims to provide a light emitting electron tube lighting device that suppresses changes in color temperature and shortening of life.

[0016]

[Means for Solving the Problems] In order to achieve the above object, in the invention of claim 1, a filament serving as a cathode and an accelerating electrode for accelerating electrons emitted from the filament are arranged so that collision of accelerated electrons causes In a light-emitting electron tube lighting device that lights a light-emitting electron tube placed oppositely in a bulb filled with a light-emitting gas that emits light when excited, an acceleration device that accelerates electrons emitted from the filament is placed between a filament and an acceleration electrode. By detecting the tube voltage between the lighting power supply means that applies voltage, the filament and the accelerating electrode, and increasing or decreasing the heating power supplied to the filament from the filament heating means according to the level of the tube voltage. The tube is equipped with filament heating means for keeping the tube voltage approximately constant.

[0017] In the invention of claim 2, the lighting power supply means includes:
The filament heating means includes an alternating power generation section that generates alternating power, and the filament heating means includes a heating transformer that supplies part of the output of the alternating power generation section to the filament, and a switch element that turns on and off the power supply from the heating transformer to the filament. , and a heating period control circuit that adjusts the on time of the switch element according to the tube voltage of the light emitting electron tube.

In the third aspect of the invention, the filament heating means includes a high frequency generating circuit which is powered by the tube voltage of the light emitting electron tube and outputs high frequency power, and a high frequency generating circuit which outputs high frequency power according to the tube voltage of the light emitting electron tube. The filament is supplied with high-frequency power through a heating transformer provided at the output section of the high-frequency generating circuit.

[0019]

[Operation] According to the structure of claim 1, even if the tube current changes, the tube voltage is kept almost constant by adjusting the power supplied to the filament, so the tube voltage changes as the tube current changes. This makes it possible to suppress changes in the color temperature of the emitted light due to this. Furthermore, it is possible to suppress the sputtering phenomenon that targets the filament due to an increase in tube voltage, and it is possible to suppress blackening of the bulb and shortening of the life of the filament.

According to the second aspect of the present invention, a part of the output of the lighting power supply means is used for heating the filament via the heating transformer, so that the structure of the filament heating means is simplified. According to the configuration of claim 3, since the tube voltage of the light emitting electron tube is used as the power source for the filament heating means, there is an advantage that the power supply route to the filament heating means and the tube voltage detection route can be shared. Moreover, when the tube voltage is high and the power supplied to the filament is increased, the power supply voltage of the filament heating means is high, making it easier to obtain the necessary power.

[0021]

【Example】

(Example 1) In this example, as shown in FIG.
Unlike the light-emitting electron tube 1 shown in FIG. 1, a pair of filaments 1b are placed opposite each other in a bulb 1a. That is, this light-emitting electron tube 1 is used when the accelerating voltage is alternating current, and both filaments 1b are also used as accelerating electrodes. As a result, electrons are emitted from the filament 1b which is a negative electrode at each time point, and the filament 1b which is a positive electrode functions as an accelerating electrode.

A lighting power supply 2, which is a lighting power supply means for applying an accelerating voltage between both filaments 1b, is connected to one end of each filament 1b.
A filament heating circuit 3, which is filament heating means for supplying heating power between both ends of each filament 1b, is connected to the filament heating circuit 3. The lighting power source 2 is powered by an AC power source AC such as a commercial AC power source, and is configured to provide an alternating output with adjustable output current. The tube voltage between both filaments 1b of the light-emitting electron tube 1 is input to the filament heating circuit 3, and the filament 1 is adjusted according to the tube voltage.
It is configured to change the heating power supplied to b. That is, as shown in FIG. 2, in this type of light-emitting electron tube 1, the heating power is controlled based on the knowledge that the tube voltage changes depending on the heating power to the filament 1b. Therefore, the filament 1b is heated according to the level of the tube voltage detected by the filament heating circuit 3.
By controlling the tube voltage by increasing or decreasing the heating power supplied to the tube, the tube voltage is kept within a substantially constant appropriate range. In short, if the tube voltage increases, filament 1b
If the tube voltage decreases, the power supplied to the filament 1b is decreased. Here, in the filament heating circuit 3 of FIG. 1, the tube voltage of the light emitting electron tube 1 is detected by one line, but the ground sides of the lighting power supply 2 and the filament heating circuit 3 are commonly connected. The railway line is omitted as it is assumed that there is a line.

The circuit shown in FIG. 3 is a specific circuit corresponding to the configuration shown in FIG. The lighting power supply 2 includes a DC power supply unit 2c that obtains DC power from an AC power supply AC, an inverter unit 2a that is an alternating power generation unit that converts the DC output of the DC power supply unit 2c into alternating power, and an output of the inverter unit 2a. and a control circuit 2b that controls the frequency and on-duty of. The DC power supply unit 2c rectifies the AC input from the AC power supply AC with a bridge rectifier RE1 made of a diode bridge, and then smoothes it with a capacitor C1. The inverter section 2a includes a series circuit of a pair of switching elements Q1 and Q2 connected between both ends of a DC power supply section 2c, and a capacitor C2 and a primary winding of a heating transformer T1 are connected between both ends of one switching element Q2. A series circuit of the line and switching element Q3 is connected. Furthermore, one end of one filament 1b is connected to the connection point between the capacitor C2 and the primary winding of the heating transformer T1 via the inductor L1, and the other filament 1b is connected to the connection point between the switching element Q2 and the switching element Q3. One end of 1b is connected. Switching elements Q1, Q
2 are controlled to be alternately and selectively turned on by the control circuit 2b. In short, the inverter section 2b is composed of switching elements Q1, Q2, a capacitor C2, and an inductor L1, and the control circuit 2
b, the capacitor C2 is charged when the switching element Q1 is on, and the capacitor C2 is discharged when the switching element Q2 is on, so that both filaments 1b of the light-emitting electron tube 1 are An alternating current voltage can be applied between them. Since an accelerating voltage is applied to the light emitting electron tube 1 via the inductor L1, the switching element Q
By controlling the switching frequency and on-duty of the light-emitting electron tube 1 and Q2, the tube current of the light-emitting electron tube 1 can be controlled and dimmed.

On the other hand, the heating transformer T1 includes a pair of secondary windings connected to each filament 1b. Further, the switching element Q3 is controlled on and off by the heating period control circuit 3a. That is, the filament heating circuit 3 includes a heating transformer T1, a switching element Q3 which is a switching element, and a heating period control circuit 3a.

The heating period control circuit 3a includes a light emitting electron tube 1
When the tube voltage is equal to or higher than a preset voltage, the switching element Q3 is turned on to supply electric power to the filament 1b and heat the filament 1b. That is, as the tube voltage increases, the power supplied to the filament 1b is increased to lower the tube voltage. Further, if the tube voltage is less than the set voltage, the switching element Q3 is turned off and power supply to the filament 1b is stopped. That is, when the tube voltage decreases, the power supplied to the filament 1b is reduced to increase the tube voltage. By performing such control, the tube voltage can be kept almost constant. Here, before the light-emitting electron tube 1 is turned on, the amount of electrons emitted from the filament 1b is insufficient and the tube voltage is higher than the set voltage, so the switching element Q3
is turned on, power is supplied to the filament 1b, and preheating is performed. When the filament 1b is heated and a sufficient amount of electrons are emitted, the light emitting electron tube 1 is automatically turned on.

With the above configuration, for example, when the ambient temperature changes, control as shown in FIG. 4 is performed. That is, if the ambient temperature rises from a low ambient temperature as shown in the left half of FIG. 4(a) to as shown in the right half, the power for heating the filament 1b is not controlled. In this case, the tube voltage will decrease in stages as shown in FIG. 4(b). On the other hand, in the case of this embodiment, when the ambient temperature is low and the amount of electron emission is insufficient and the tube voltage is higher than the set reference voltage SL as shown in FIG. 4(e), the heating period control circuit 3a generates a control voltage as shown in FIG. 4(c), turning on the switching element Q3. That is, for the filament 1b in FIG.
A large amount of power will be supplied as shown in d). Therefore, the tube voltage gradually decreases and reaches the reference voltage SL. At this time, the switching element Q3 is controlled to alternately turn on and off as shown in FIG. 4(c), and the heating power is maintained at an appropriate state as shown in FIG. 4(d). Here, as the ambient temperature rises, the amount of electrons emitted from the filament 1b increases, so as shown in FIG. 4(e)
As shown in FIG. 4(
As shown in c), switching element Q3 is turned off,
As shown in FIG. 4(d), the power supply to the filament 1b is stopped. Therefore, the tube voltage gradually increases and stabilizes around the reference voltage SL again. In this way, since the tube voltage is kept almost constant, changes in color temperature and shortening of lifespan are suppressed.

(Embodiment 2) As shown in FIG. 5, in comparison with Embodiment 1, this embodiment omits the switching element Q3 connected in series with the primary winding of the heating transformer T1, and replaces it with The difference is that a filament 1b is connected to the secondary winding of the heating transformer T1 via switching elements Q31 and Q32, respectively. Both switching elements Q31 and Q32 are controlled on and off by the heating period control circuit 3a, and when they are on, heating power is supplied to the filament 1b, so they perform the same operation as in the first embodiment. . This embodiment differs from Embodiment 1 only in the insertion points of switching elements Q31 and Q32, and the other configurations and operations are the same as in Embodiment 1, so explanations thereof will be omitted.

(Embodiment 3) As shown in FIG. 6, this embodiment uses the light emitting electron tube 1 shown in FIG. There is. Therefore, the output of the inverter section 2a is stepped down by the output transformer T2, and the output voltage of the inverter section 2a is stepped down by the output transformer T2.
After being rectified by C2 and smoothed by a capacitor C3, it is applied between the filament 1b of the light-emitting electron tube 1 and the accelerating electrode 1c. Here, both ends of the secondary winding of a coupling transformer T3 are connected to both ends of the filament 1b, and one end of a capacitor C3 is connected to a center tap provided on the secondary winding via a switching element Q4. One end of the secondary winding of the heating transformer T1 that supplies power for heating the filament 1b is connected to one end of the primary winding of the coupling transformer T3, and the other end of the secondary winding of the heating transformer T1 is connected to the control transformer. 1 of T4
It is connected to the other end of the primary winding of the coupling transformer T3 via the secondary winding. The secondary winding of the control transformer T4 is connected to the heating period control circuit 3a. The heating period control circuit 3a includes a comparator CP that compares the tube voltage of the light emitting electron tube 1 with a predetermined set voltage, and a reference power supply SV that generates a reference voltage for the comparator CP. The output of this comparator CP causes a bridge rectifier RE2 consisting of a diode bridge.
The switching element Q3 connected between the DC terminals of the switching element Q3 is controlled to be turned on or off. In addition, the comparator CP has hysteresis, so that when the tube voltage of the light emitting electron tube 1 exceeds the upper limit of the setting range and the switching element Q3 is turned on, the state remains until the tube voltage falls below the lower limit. maintain. The secondary winding of the control transformer T4 is connected to the bridge rectifier RE.
When the switching element Q3 is on, the inductance of the primary winding of the control transformer T4 becomes small, and the heating transformer T1
The power supplied to the coupling transformer T3 increases. Conversely, when the switching element Q3 is off, the power supplied to the coupling transformer T3 decreases. In short, if the tube voltage increases, the tube voltage is lowered by increasing the power supplied to the filament 1b, and if the tube voltage decreases, the tube voltage is increased by reducing the power supplied to the filament 1b. Here, the switching element Q4 is provided to perform preheating without applying an accelerating voltage by turning off the light-emitting electron tube 1 before lighting it, and is always turned on after lighting. The other configurations and operations are the same as those in the first embodiment, so their explanations will be omitted.

(Embodiment 4) In each of the above embodiments, a part of the output of the inverter section 2a was used for heating the filament 1b, but in this embodiment, as shown in FIG. The filament heating circuit 3 is operated using the tube voltage of 1 as a power source. Further, the filament heating circuit 3 is constituted by an inverter circuit. That is, since the power for the filament heating circuit 3 is obtained from the tube voltage of the light emitting electron tube 1, the line for detecting the tube voltage is also used as a power supply line, and moreover, the high tube voltage is used during preheating. By obtaining this, it becomes easier to obtain electric power for preheating. Furthermore, even when the tube voltage increases and it is necessary to increase the power supplied to the filament 1b, it becomes easier to obtain heating power. As the light-emitting electron tube 1, an alternating current tube having filaments 1b at both poles is used. Note that the power source for the filament heating circuit 3 may be provided separately. The other configurations and operations are the same as those in the first embodiment, so their explanations will be omitted.

(Embodiment 5) This embodiment is a specific example of the filament heating circuit 3 in Embodiment 4, and the lighting power source 2 is constructed so as to obtain a DC output. Therefore, as shown in FIG. 8, a light emitting electron tube 1 having the configuration shown in FIG. 13 is used. Also, filament 1b
One end opposite to the one end connected to the negative electrode of the lighting power supply 2 is grounded, and a smoothing capacitor C4 is connected between the ground electrode and the acceleration electrode 1c. The voltage across this capacitor C4 becomes the power source for the filament heating circuit 3.

The filament heating circuit 3 is a switching regulator integrated circuit IC1 (for example, NEC
The main component is μPC494) manufactured by
A rectangular wave is output from the 8th terminal and the 11th terminal. The frequency of the output signal is determined by the capacitor C6 and the resistor R6, and the on-duty is 0 to 1.
It can be controlled within a range of 0.00%. Terminal 8 and 11
The rectangular wave output from the number terminal and the inverting circuit IC2 (
For example, the signal is inverted and waveform-shaped through a μPC4049 (manufactured by NEC), and a switching element Q5 made of a MOSFET is controlled on and off. The switching element Q5 is connected in series with the primary winding of the heating transformer T1 via a diode D5, and this series circuit is connected across the capacitor C4. In addition, a capacitor C is connected to the primary winding of the heating transformer T1.
5 are connected in parallel. When the switching element Q5 is turned on, current flows through the primary winding of the heating transformer T1 and at the same time the capacitor C5 is charged. When the switching element Q5 is turned off, the energy stored in the primary winding is released and the capacitor C5 is charged. The charge accumulated in C5 is released. Therefore, an alternating current voltage is induced in the secondary winding of the heating transformer T1. That is, the heating transformer T1, the switching element Q5, the diode D5, and the capacitor C5 constitute a high frequency generation circuit 3b consisting of a single-stone inverter circuit.
The output of the high frequency generation circuit 3b is a power control circuit 3c whose main components include an integrated circuit IC1 and an inverting circuit IC2.
It is controlled by the output of Here, the longer the on-time of the switching element Q5, the greater the output power from the secondary winding of the heating transformer T1.

By the way, in the integrated circuit IC1, a reference voltage of 5V is outputted from the reference terminal which is the 14th terminal, and a voltage obtained by dividing the tube voltage of the light emitting electron tube 1 by the variable resistor VR is outputted to the 2nd terminal. Input the reference voltage to 1
By inputting the signal to the terminal No. 1, the on-duty of the output signal is controlled according to the difference in input voltage between the No. 1 terminal and the No. 2 terminal. That is, the voltage divided by the variable resistor VR is higher than the reference voltage, and the larger the difference, the smaller the on-duty becomes. Since this output is inverted by the inverting circuit IC2,
As the tube voltage increases, the on time of the switching element Q5 becomes longer, and as a result, the filament 1
This increases the amount of power used to heat b. That is, when the tube voltage of the light-emitting electron tube 1 increases, the electric power for heating the filament 1b increases, thereby lowering the tube voltage. Conversely, if the tube voltage decreases, the heating power decreases and the tube voltage increases. A voltage obtained by dividing the reference voltage by resistors R7 and R8 is applied to the No. 4 terminal of the integrated circuit IC1, and by limiting the lower limit of the on-duty of the output signal of the integrated circuit IC1, the filament 1
This prevents the power supplied to b from becoming excessive.

According to the above configuration, the tube voltage of the light-emitting electron tube 1 can be kept substantially constant, and changes in color temperature can be suppressed, as well as shortening of the life span. In addition, the power source for the single-stone inverter section can be obtained from the tube voltage of the light emitting electron tube 1, and this tube voltage is a relatively low voltage (usually set to 41 V or less, preferably 20 V or less). , switching element Q5
There is no need to use one with high breakdown voltage.

(Embodiment 6) In Embodiment 5, the filament heating circuit 3 was constructed using a single-stone type inverter section, but in this embodiment, as shown in FIG. 9, a half-bridge type inverter section was used. This is the one using the part. The light-emitting electron tube 1 used is one for AC lighting, in which a pair of filaments 1b are placed opposite each other.

That is, the filament heating circuit 3 uses the tube voltage of the light emitting electron tube 1 as a power source, and converts the tube voltage into a bridge rectifier RE3 consisting of a diode bridge.
After full-wave rectification by C8, DC power is obtained by smoothing by capacitor C8. A series circuit of a pair of switching elements Q6 and Q7 is connected between both ends of the capacitor C8, and each switching element Q6 and Q7 is controlled to be alternately and selectively turned on by the power control circuit 3c. A capacitor C7 is connected between both ends of the switching element Q7.
, an inductor L2, and a series circuit of the primary winding of the heating transformer T1 are connected. The heating transformer T1 includes a pair of secondary windings, each of which is connected to each filament 1b of the light-emitting electron tube 1, respectively. Power control circuit 3c
The tube voltage of the light-emitting electron tube 1 is detected by the voltage across the capacitor C8, and as in each of the above embodiments, when the tube voltage increases, the tube voltage is increased by increasing the power supplied to the filament 1b. control to lower it. The power supplied to the filament 1b is supplied to the switching element Q6.
, Q7 by controlling the switching frequency and on-duty. Here, the power for the filament heating circuit 3 is obtained from the tube voltage of the light emitting electron tube 1, so when the tube voltage is high and it is necessary to increase the power supplied to the filament 1b, it is easier to obtain heating power. It is.

Control signals to both switching elements Q6 and Q7 can be input directly to switching elements Q6 and Q7 without providing electrical insulation via a transformer or the like. Note that although a half-bridge type inverter section is disclosed in this embodiment, a full-bridge type inverter section in which four switching elements are connected to form a bridge circuit may be used to operate in the same manner.

(Embodiment 7) As shown in each of the above embodiments, a heating transformer T1 is required to heat the filament 1b. In order to downsize the heating transformer T1 and obtain high power transmission efficiency, it is desirable to configure the heating transformer T1 for high frequency use. Therefore, high frequency power is used to heat the filament 1b, and if the current waveform supplied to the filament 1b is distorted, radiation noise will occur. Therefore, in this embodiment, as shown in FIGS. 10 to 12,
The noise filter NF is inserted in the path from the filament heating circuit 3 to the filament 1b. This noise filter NF is configured to pass the fundamental wave component of the electric power for heating the filament 1b, but to block the harmonic wave component. By using such a noise filter NF, radiation noise is reduced.

[0038]

As described above, according to the structure of claim 1, even if the tube current changes, the tube voltage is kept almost constant by adjusting the power supplied to the filament. Accordingly, there is an advantage that a change in the color temperature of the emitted light color due to a change in the tube voltage can be suppressed. Furthermore, it is possible to suppress the sputtering phenomenon that targets the filament due to an increase in tube voltage, and has the effect of suppressing blackening of the bulb and shortening of the life of the filament.

According to the second aspect of the present invention, a part of the output of the lighting power supply means is used for heating the filament via the heating transformer, so that the structure of the filament heating means is simplified. According to the configuration of claim 3, since the tube voltage of the light emitting electron tube is used as the power source for the filament heating means, there is an advantage that the power supply route to the filament heating means and the tube voltage detection route can be shared. Moreover, when the tube voltage is high and the power supplied to the filament is increased, the power supply voltage of the filament heating means is high, making it easier to obtain the necessary power.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment.

FIG. 2 is an explanatory diagram regarding the operating principle of the first embodiment.

FIG. 3 is a circuit diagram showing the first embodiment.

FIG. 4 is an explanatory diagram of the operation of the first embodiment.

FIG. 5 is a circuit diagram showing a second embodiment.

FIG. 6 is a circuit diagram showing a third embodiment.

FIG. 7 is a block diagram showing a fourth embodiment.

FIG. 8 is a circuit diagram showing a fifth embodiment.

FIG. 9 is a circuit diagram showing a sixth embodiment.

FIG. 10 is a circuit diagram showing a seventh embodiment.

FIG. 11 is another circuit diagram showing Example 7.

FIG. 12 is yet another circuit diagram showing Example 7.

FIG. 13 is a perspective view showing a light-emitting electron tube according to the present invention.

FIG. 14 is a circuit diagram showing a conventional example.

FIG. 15 is a circuit diagram showing another conventional example.

FIG. 16 is an explanatory diagram showing operating characteristics of a light-emitting electron tube.

FIG. 17 is an explanatory diagram showing operating characteristics of a light-emitting electron tube.

FIG. 18 is an explanatory diagram showing operating characteristics of a light-emitting electron tube.

[Explanation of symbols]

1. Light-emitting electron tube 1a Valve 1b Filament 1c Acceleration electrode 2 Power supply for lighting 3 Filament heating circuit

Claims (3)

[Claims] Claim 1: A light emitting device in which a filament serving as a cathode and an acceleration electrode that accelerates electrons emitted from the filament are placed opposite each other in a bulb filled with a light emitting gas that emits light when excited by collisions with the accelerated electrons. In a light-emitting electron tube lighting device for lighting an electron tube, a lighting power supply means for applying an acceleration voltage for accelerating electrons emitted from the filament between a filament and an acceleration electrode; The filament heating means detects the tube voltage and keeps the tube voltage substantially constant by increasing or decreasing the heating power supplied to the filament from the filament heating means in accordance with the level of the tube voltage. Light emitting electron tube lighting device. 2. The lighting power supply means includes an alternating power generation section that generates alternating power, and the filament heating means comprises:
A heating transformer that supplies part of the output of the alternating power generator to the filament, a switch element that turns on and off the power supply from the heating transformer to the filament, and an on-time adjustment of the switch element according to the tube voltage of the light-emitting electron tube. 2. The light emitting electron tube lighting device according to claim 1, further comprising a heating period control circuit. 3. The filament heating means comprises a high-frequency generation circuit that is powered by the tube voltage of the light-emitting electron tube and outputs high-frequency power, and a power control circuit that adjusts the output power of the high-frequency generation circuit according to the tube voltage of the light-emission electron tube. 2. The light-emitting electron tube lighting device according to claim 1, further comprising: a heating transformer provided at the output section of the high-frequency generating circuit to supply high-frequency power to the filament.