JPH01292797A - Fluorescent lamp lighting device - Google Patents

Abstract

PURPOSE:To aim at improvement of reliability coupled with a reduction of power consumption by giving the alarm for a disconnection of a filament through a judgement based on the discrimination of the number of high frequency if it is the value obtained when a filament of a fluorescent lamp works normally or is the one obtained when it is disconnected. CONSTITUTION:Oscillating frequency of a high-frequency inverter circuit 1 is small when a fluorescent lamp 2 is burnt normally, whereas it becomes large in the anomalous case where a filament is disconnected. By discriminating a difference in frequency, a means of discrimination 5 judges whether the fluorescent lamp 2 is burning normally or not and outputs the signal that is an index of the discrimination to a means of annunciation 6. The means of annunciation 6 executes a burning or a putting off of a lamp or works as a display according to the input signal, in order to announce a disconnection of a filament of the fluorescent lamp 2. Thus an improvement of reliability and a reduction of superfluous power consumption are achieved at the same time.

Description

[Detailed Description of the Invention] [Field of Application] The present invention relates to a fluorescent lamp lighting device, and particularly to a liquid crystal display device.
The present invention relates to a fluorescent lamp lighting device for temporary lighting used in original binding for back lighting such as t.

[Conventional technology]

BACKGROUND ART Conventionally, a liquid crystal display type meter using a fluorescent lamp as a backlight has been proposed as a meter for the driver's seat of an automobile.

An example of a publication disclosing a technique related to a lighting device for a polar fluorescent lamp is described in Japanese Patent Application Laid-open No. 75597/1983. The lighting device for a fluorescent lamp disclosed in the publication includes a preheating circuit for preheating the filament of the fluorescent lamp in order to be able to detect at an early stage whether or not the filament of the fluorescent lamp is broken. The miniature light bulbs are connected in series.

According to this device, when the filament of the fluorescent lamp is normal, the miniature bulb lights up, and when the filament is VR-kneaded, the miniature bulb goes out. You can easily tell whether something is normal or not.

[Problem that the invention seeks to solve]

In the conventional device described above, since there are two filaments in the fluorescent lamp, it is necessary to provide a small bulb in both circuits, and there is a problem that the polarization is low, and even when the IR source lamp is lit normally, the two filaments are connected to each other. There was a problem in that miniature light bulbs required unnecessary electricity to be lit.

The purpose of the present invention is to eliminate the problems of the conventional device described above,
1! ! An object of the present invention is to provide a fluorescent lamp lighting device that is highly reliable and can reduce wasteful power consumption.

[Means for solving problems]

The above purpose is to monitor the transmission frequency IHL of a high frequency inverter circuit that lights a fluorescent lamp at high frequency, and to provide a discriminating means for determining whether the fluorescent lamp is normally lit or abnormally lit due to a filament break. This can be achieved by providing a warning means that notifies you when the lighting is abnormal.

[Effect]

The oscillation frequency of the Shima-Shusaka inverter circuit is low when the fluorescent lamp is normally lit, and becomes high when there is an abnormality due to filament breakage. The determining means determines whether or not the fluorescent lamp is normally lit by determining the difference in frequency. Further, the discrimination means outputs a signal indicating the discrimination result to the notification handout.

In accordance with the input signal, the notifying means notifies the filament breakage of a bamboo lamp or a fluorescent lamp that does not turn on, off, or displays a display.

〔Example〕

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

FIG. 1 shows a circuit diagram of an embodiment of the present invention.

In the figure, reference numeral 1 denotes a fluorescent lamp lighting circuit using a general two-channel push-nable inverter system.

2 is a fluorescent lamp connected to the secondary side of the transformer of the fluorescent lamp lighting circuit 1; 5 is a filament of the original lamp 2; Further, the (g circuit) consisting of the secondary winding #22, the capacitor C3, and the filament 6, and the circuit consisting of the &C secondary winding N22, the capacitor C4, and the filament 5 are preheating circuits for the filament 5.

4 is a disconnection detection circuit which is a main part of this embodiment. The disconnection detection circuit 4 includes resistors R4 to R9 and transistors 15 to
T5, monostable multivibrator 5, capacitor C5,
C6, a diode D1, and a monitor lamp 6, as shown in the drawing.

Next, the operation of this embodiment will be explained. The oscillation frequency of the fluorescent lamp lighting circuit 1 of this embodiment is as follows when the fluorescent lamp 2 is normally lit and when the filament 5 is broken.

Said 1! The oscillation frequency f of the original lamp lighting circuit 1 is determined by the following equation when the fluorescent lamp 2 is normally lit.

Here, L and C1 are the primary side inductance and capacitor capacity t of the oscillation transformer, C2#C5#C4 is the capacity weight of the secondary side current control capacitor, N1 is the number of turns on the primary side,
A'21 and N22 are the numbers of turns on the secondary side.

On the other hand, among the filaments 5 of the fluorescent lamp 2, for example, if the filament 3 connected to the capacitor C5 side is disconnected, the oscillation frequency j1 of the fluorescent lamp lighting circuit 1
is higher than the frequency j shown in equation (1) above.

Similarly, if the filament 3 connected to the capacitor C41111 is bent, the fluorescent lamp lighting circuit 1
The oscillation frequency j, is compared to the period γ inverse number f shown in equation (1) above, l−
te high (naru)

Further, the oscillation station r & ridge f of the fluorescent lamp lighting circuit 1 when both the filament 5 connected to C39111 and the filament 5 connected to C4* are disconnected,
, which is also higher than the frequency f indicated by (1+large).

As described above, the fluorescent lamp lighting circuit 1 The +6 vibration frequency rfL numbers are different.

The oscillation output of the fluorescent lamp lighting circuit 10 having the MIJ oscillation frequency j, ji-j4, or j is input to the base of the transistor T5 via the resistor R4, and is waveform-shaped by the transistor T3. The M-waveform shaped signal is input to the input terminal A of the monostable Kelch biprator 5.

Here, the output monostable pulse width T of the monostable multivibrator 5 is determined by the time constant of the external resistor R6 and capacitor C5. In this practical example, as shown in FIG. 2, the oscillation frequency of the fluorescent lamp lighting circuit 1 is set to f (cycle T, ) when the fluorescent lamp 2 is normally lit, When one filament 5 is I#r line &cf4 (peripheral IJAT, ), the output monostable pulse width T of the monostable multivibrator 5 is TI>
The temperature is set so that T > T.

As a result, when the fluorescent lamp 2 is lit normally,
The output pulse of pulse @T is monostable multivibrator 5
is output from the output terminal Q of the transistor T4, and the transistor T4 is turned on.
Turns off. The collector voltage of the transistor T4 has a waveform as shown in FIG. Once this occurs, charge is stored in the capacitor C6 via the resistor R8 and the diode D1, and the potential 6 on the cathode side of the diode D1 becomes high level. Therefore, the transistor T5 is turned on, and the monitor lamp 6 (incandescent light bulb or light emitting diode) can be turned on.

Next, in the fluorescent lamp lighting circuit I, if either one of the filaments 5 of the fluorescent lamps 2 becomes unstable, the output from the output terminal Q of the monostable multivibrator 5 will be as shown in FIG. As shown in FIG. Therefore, the capacitor C6 is not charged and remains discharged, so that the voltage 4 on the cathode side of the diode D1 becomes a level, and the transistor T5 is turned off. ℃, the monitor lamp 6 is turned off, and it is possible to detect that the filament 5 of the fluorescent lamp 2 is disconnected.

In this embodiment, the transistor T5 is PN.
P) If a transistor is used instead, it would be possible to turn off the monitor lamp 6 when the fluorescent lamp 2 is normally lit, and turn on the lamp 6 when the filament 5 is broken.

FIG. 3 shows another embodiment of the disconnection detection circuit 4 shown in FIG. 1. In this example, the oscillation frequency of a fluorescent lamp lighting circuit 10 using a high frequency inverter is inputted to a microcomputer 7 shaped by a transistor T3. Based on the frequency or period of the input signal, the microcomputer 7 determines whether the fluorescent lamp 2 is lighting normally or whether the filament 3 is
Determine whether the person is present or not.

As a result, if the fluorescent lamp 2 is normally lit, the micro combinator 7 does not output any output signal. - If one of the filaments 5 of the fluorescent lamp 2 is exposed to W'r radiation, the transistor T6 from the micro combinator 7 is turned on to light the monitor lamp 8, and the fluorescent lamp Make them aware that it is the filament cut edge of No. 2.

Note that instead of the monitor lamp 8, a liquid crystal display element or a device that outputs a sound may be used to display a monitor indicating that the filament 5 of the fluorescent lamp 2 is at the @ line. .

As described above, according to the above-mentioned practical example, since only one monitor lamp is required, compared to the conventional one, the monitor lamp is disconnected and the fluorescent lamp Q) filament normality,
This has the effect of greatly improving the probability that an abnormality cannot be detected.Also, according to the first and second embodiments of BA, when the fluorescent lamp is normally lit, the monitor lamp of Since the light is on or off, wasteful power consumption can be reduced.

〔Effect of the invention〕

According to the present invention, the oscillation frequency of a high-frequency inverter circuit that lights a fluorescent lamp at high frequency is different between when the fluorescent lamp is normally lit and when the fluorescent lamp is abnormally lit due to a break in the filament. Since it is possible to detect whether the filament of the fluorescent lamp is normal or abnormal, only one lamp is required for monitoring, and the probability of misjudgment due to failure of the monitoring lamp can be halved. For this reason, it has a long history of being highly reliable.

Further, when the fluorescent lamp is normally lit, one monitor lamp (noted separately) is lit or is in a white-lit state, which has the effect of reducing wasteful power consumption.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a fluorescent lamp lighting device according to an embodiment of the present invention, FIG. 2 is a time chart showing the operating waveforms of the main signals in FIG. 1, and FIG. 3 is a circuit diagram of a fluorescent lamp lighting device according to an embodiment of the present invention. It is a circuit diagram of an example. 1...Fluorescent lamp lighting circuit 2...*Original lamp 5...
・Filament 4...Disconnection detection circuit 5...Monostable multivibrator 7...Microcomputer 6.8...Monitor lamp agent

Claims (1)

[Scope of Claims] 1. In a fluorescent lamp lighting device for lighting a fluorescent lamp at high frequency, means for determining whether the frequency of the high frequency is a value when the filament of the fluorescent lamp is normal or a value when the filament of the fluorescent lamp is broken. . A fluorescent lamp lighting device comprising: warning means for warning of breakage of the filament based on the determination result of the means. 2. The fluorescent lamp lighting device according to claim 1, wherein the alarm means is one monitor lamp that is turned on or off when the filament is broken.