JPH097779A - Fluorescent lamp lighting control device - Google Patents

Abstract

(57) [Abstract] [Purpose] A fluorescent lamp lighting control device for preventing abnormal discharge from the filament of a fluorescent lamp, preventing scattering of electron emission material on the filament, and maintaining the life of the fluorescent lamp. provide. [Structure] The detection circuit 1-7 detects the current of each filament 2-7 of the fluorescent lamp 1-1, and the control circuit 1-3
When the detected current value is smaller than the predetermined value, the signal 1-5
Thus, the operation of the high frequency power supply 2-5 is stopped. In this way, when the preheating of the filament 2-7 is not sufficient, the energization of the fluorescent lamp 1-1 is stopped to prevent abnormal discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting control device for a fluorescent lamp.

[0002]

2. Description of the Related Art Conventionally, in a fluorescent lamp lighting device, in order to start lighting of a fluorescent lamp, electric power is applied to filaments at both ends of the fluorescent lamp to heat them (hereinafter, this is referred to as preheating), and thermoelectric In general, a method is used in which a voltage is applied between filaments in the state of being sufficiently discharged to cause discharge, and lighting is started.

[0003]

However, in the above-described conventional example, when there is an abnormality in the preheating circuit of the fluorescent lamp, when the power supply line to the fluorescent lamp is broken, or when the preheating time is exceeded. If the discharge is not performed for the time required to start the discharge, the discharge will start with the filament temperature low, and normal lighting will not be possible.If the lighting operation is repeated in this state, the electron emission material on the filament will scatter. However, there has been a problem that the life of the fluorescent lamp is extremely shortened.

The present invention has been made under such circumstances, and prevents abnormal discharge from the filament of the fluorescent lamp and prevents scattering of electron emission material of the filament, thereby shortening the life of the fluorescent lamp. Can hold,
An object of the present invention is to provide a fluorescent lamp lighting control device.

[0005]

In order to achieve the above-mentioned object, the present invention provides a fluorescent lamp lighting control device as follows.
Configure as in (7).

(1) First driving means for preheating the filament of the fluorescent lamp, detecting means for detecting that the filament is preheated, and a lamp current for flowing the fluorescent lamp. A fluorescent lamp lighting control device comprising a second drive means and a control means for controlling the operation of the second drive means based on the output of the detection means.

(2) The fluorescent lamp lighting control according to (1), wherein the control means prohibits the operation of the second driving means when the detecting means does not detect that the filament is preheated. apparatus.

(3) The fluorescent lamp lighting control device according to (1), wherein the detecting means is provided for each filament at both ends of the fluorescent lamp.

(4) The fluorescent lamp lighting control device according to any one of (1) to (3), wherein the detection means detects a current flowing through the filament.

(5) The fluorescent lamp lighting control device according to any one of (1) to (3), wherein the detection means is an optical sensor provided near the filament.

(6) The comparison means compares the filament current value detected by the detection means with a preset predetermined value, and the control means detects the filament detected by the detection means as a result of the comparison by the comparison means. The fluorescent lamp lighting control device according to (1), wherein when the current value is smaller than the predetermined value, the operation of the second drive means is prohibited.

(7) It has a measuring means for measuring the duration of the signal detected by the detecting means, and a comparing means for comparing the value measured by this measuring means with a preset predetermined value. As a result of comparison by the comparison means, when the value measured by the measurement means is smaller than the predetermined value, the operation of the second drive means is prohibited, and the fluorescent lamp lighting control device according to (1).

[0013]

With the configurations (1) to (7), the operation of the second drive means for flowing the lamp current is controlled according to the preheating state. Specifically, in the above configuration (2), when it is not detected that the filament is preheated,
That is, when preheating is not being performed, the control means is the second
The operation of the driving means is prohibited. In the configuration of (3) above,
Preheating is detected for each filament. In the configuration (4), residual heat is detected by the filament current, and in the configuration (5), preheating is detected by the optical sensor near the filament. In the configuration of (6), the operation of the second drive unit is prohibited when the filament current value does not reach the predetermined value. In the configuration of (7), the operation of the second driving unit is prohibited when the duration of the filament current does not reach the predetermined value.

[0014]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 is a block diagram of a "fluorescent lamp lighting control device" according to the first embodiment. In FIG. 1, 1-1 is a fluorescent lamp, 1-2 is a drive circuit for preheating the filament of the fluorescent lamp 1-1, and a lamp current is supplied to the fluorescent lamp 1-1 when the fluorescent lamp 1-1 is turned on. It is a drive circuit for flowing. Reference numeral 1-3 is a control circuit for controlling the drive circuit 1-2, 1-4 is a control signal for switching the lamp current to the fluorescent lamp 1-1 and preheating of the filament, and 1-5 is a lamp. It is a control signal for turning on / off the high-frequency power supply for current and preheating, and is controlled by the control circuit 1-3.

The control circuit 1-3 includes a fluorescent lamp 1-1.
While detecting the amount of light by the light amount sensor 1-6 placed in the vicinity of, and changing the duty of the above-mentioned lighting control signal 1-4 based on the value, while keeping the amount of light of the fluorescent lamp 1-1 constant. It controls to turn on.

FIG. 2 is a circuit diagram showing details of the drive circuit 1-2 shown in FIG. 1. 1-1 is a fluorescent lamp, 2-5 is a high frequency power source, and 2-6 is an oscillation circuit. In this embodiment, an inverter circuit for converting the DC power supply V into a high frequency is used, and a high frequency is generated by switching the transistor 2-9 at a frequency of several tens of kilohertz, and is boosted by the transformer 2-2. Use a high frequency power supply. Fluorescent lamp 1-
The current when 1 is lit flows from the transformer 2-2 through the choke coil 2-3 between the filaments 2-7 of the fluorescent lamp 1-1 and returns to the transformer 2-2. Is called a lamp current, and the brightness of the fluorescent lamp 1-1 is controlled by this current. Also, the brightness can be controlled by turning on / off the transistor 2-4, performing PWM control, and controlling the duty of the lamp current.

Next, as a preparatory step of lighting the fluorescent lamp 1-1, preheating of the filament of the fluorescent lamp 1-1 will be described.

The fluorescent lamp is generally lit by the discharge between the filaments at both ends, and in order to carry out this discharge, an electric current is passed through the filament to cause it to glow red, and the electrons processed on the filament surface are treated. After the thermoelectrons are sufficiently emitted from the emissive material, lighting is started by applying a voltage between the filaments. At this time, if the filament is not sufficiently heated and the lighting is started, the number of thermoelectrons is insufficient and sufficient discharge is not performed between the filaments at the start of the lighting, so that the lighting may not be appropriately performed.

Not only at the start of lighting but also during lighting, particularly when the duty of the lamp current is controlled to be low, the effective temperature of the lamp current is small and the filament temperature becomes low, resulting in sufficient discharge. Is not performed and it is necessary to preheat the filament when the lamp current is off.

Next, in the above-mentioned configuration, the control circuit 1-3
From the fluorescent lamp 1 before turning on the fluorescent lamp 1-1
In order to preheat the filament No. 1, the oscillation circuit 2-6 is operated by the signal 1-5 for operating the high frequency power source 2-5, and the high frequency output voltage is generated at the output of the transformer 2-2. . At the same time, the transistor 2-4 is operated by the signal 1-4, and the output of the above-mentioned transformer 2-2 passes through the choke coil 2-3 and the one filament 2-7 of the fluorescent lamp 1-1 to the diode bridge 2
Both filaments 2-7 are heated by flowing through -8, through the transistor 2-4, through the diode bridge 2-8 and through the other filament 2-7. When the filament 2-7 is heated, a large amount of thermoelectrons are emitted from the thermoelectron emitting substance (not shown) attached to the filament surface. Transistor 2-in this state
4 is turned off, a voltage is applied between the filaments 2-7 at both ends of the fluorescent lamp 1-1.
Due to the thermoelectrons from the above, discharge is started between the filaments 2-7 and the fluorescent lamp 1-1 is turned on.

Here, 1-7 is a means for detecting a current,
It is a detection circuit for detecting a current flowing when the filament 2-7 is preheated. As described above, when the filament 2-7 before lighting the fluorescent lamp 1-1 is preheated, the output from the transformer 2-2 passes through the filament 2-7 of the fluorescent lamp 1-1 and the diode bridge 2 Since it flows to the transistor 2-4 via −8, if it is detected whether or not a current flows in the portion 1-7,
It is possible to detect whether the filament 2-7 has been preheated. Further, in order to detect whether or not the filament 2-7 has been sufficiently preheated, this detection signal is sent to the control circuit 1.
-3, the timer (not shown) in the control circuit 1-3 measures the time during which preheating is performed, and by comparing the measured value with a predetermined value of the preset time, When the measured value is shorter than the predetermined value, it is determined that the temperature of the filament 2-7 does not rise sufficiently and the amount of thermionic emission is insufficient to start lighting, and the fluorescent lamp 1-1 The operation of the oscillation circuit 2-6 is stopped by the signal 1-5 without starting the lighting and the lighting of the fluorescent lamp 1-1 is stopped. If the measured value is equal to or more than the predetermined value, it is determined that the preheating is sufficiently performed, and the transistor 2-4 is turned off by the signal from the control circuit 1-3, whereby the filament 2-7 of the fluorescent lamp 1-1. A voltage is applied between them, and discharge is started and lighting is performed.

Instead of using the timer as described above, by comparing the filament current value detected by the detection circuit 1-7 with a predetermined current value preset in the control circuit 1-3, When the detected current value is less than the predetermined value, the fluorescent lamp 1
The lighting of -1 may be stopped, and the lighting may be started if it is equal to or more than a predetermined value.

The above-described operation is performed not only at the start of lighting but also during lighting, as described above, when the transistor 2-4 is lit by duty control by the PWM signal, the transistor 2-4 is lit. When is on, the preheating current flows through the filament, and when it is off, the lamp current flows, and it is possible to detect whether or not the current is flowing through the filament 2-7 during lighting. When the preheating is not performed, the detection circuit 1-7 can determine whether or not the preheating is performed. Therefore, if the preheating is not performed, the lighting can be stopped.

Further, the detection circuit 1-for detecting the above-mentioned preheating.
By providing 7 on both sides of the filament 2-7 of the fluorescent lamp 1-1 as shown in FIG. 2, it is possible to stop the lighting if either one of them is not preheated.

As means for detecting the preheating of the filament 2-7, in addition to detecting the current flowing through the filament, for example, as shown in FIG. 1, optical sensors 1-8 are provided in the vicinity of the filaments at both ends. Alternatively, it may be possible to detect whether or not the preheating is performed by detecting that the filament is red-heated during the preheating.

As described above, when the preheating of the filament is not sufficient, it is possible to prohibit energization of the discharge lamp, prevent abnormal discharge from the filament, and prevent scattering of the electron emitting substance on the filament. The life of the fluorescent lamp can be maintained.

[0028]

As described above, according to the present invention,
It is possible to prevent abnormal discharge of the fluorescent lamp, prevent scattering of the electron emitting material on the filament, and maintain the life of the fluorescent lamp.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment.

FIG. 2 is a circuit diagram of a drive circuit according to an embodiment.

[Explanation of symbols]

 1-1 Fluorescent lamp 1-2 Drive circuit 1-3 Control circuit 1-7 Detection circuit

Claims (7)

[Claims] 1. A first drive means for preheating a filament of a fluorescent lamp, a detection means for detecting that the filament is preheated, and a first means for supplying a lamp current to the fluorescent lamp. 2. A fluorescent lamp lighting control device comprising: a second driving means; and a control means for controlling the operation of the second driving means based on the output of the detecting means. 2. The fluorescence according to claim 1, wherein the control means prohibits the operation of the second drive means when the detection means does not detect that the filament is preheated. Lighting control device. 3. The detecting means is provided for each filament at both ends of the fluorescent lamp.
The fluorescent lamp lighting control device described. 4. The fluorescent lamp lighting control device according to claim 1, wherein the detection means detects a current flowing through the filament. 5. The fluorescent lamp lighting control device according to claim 1, wherein the detection means is an optical sensor provided near the filament. 6. A filament current detected by the detection means is provided as a result of the comparison means comparing the filament current value detected by the detection means with a preset predetermined value. 2. The fluorescent lamp lighting control device according to claim 1, wherein when the value is smaller than the predetermined value, the operation of the second drive means is prohibited. 7. The measuring means for measuring the duration of the signal detected by the detecting means, and the comparing means for comparing the value measured by the measuring means with a predetermined value set in advance, the control means comprising: The fluorescent lamp lighting control device according to claim 1, wherein when the value measured by the measuring means is smaller than the predetermined value as a result of comparison by the means, the operation of the second driving means is prohibited.