JPS6059699A - Fluorescent lamp unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fluorescent lamp device, and more particularly to a fluorescent lamp device for controlling the luminance of a fluorescent lamp.

BACKGROUND TECHNOLOGY The luminance of conventional fluorescent lamps varies greatly depending on the temperature of the tube wall, so when these fluorescent lamps are used, for example, to illuminate automobile meters, the luminance is low at low temperatures, making it difficult to see the meter display. There was a problem. Also, if you leave this fluorescent lamp on for a long time, the luminance will increase due to the rise in tube wall temperature due to self-heating, and the meter display may become dazzling, especially at night.
・There was a problem.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems.The purpose of the present invention is to variably control the tube current of a fluorescent lamp depending on the tube wall temperature of the fluorescent lamp. It is an object of the present invention to provide a fluorescent lamp device that can eliminate temperature dependence and maintain the luminance within an appropriate range.

Structure of the Present Invention In order to achieve the above objects, the present invention includes a temperature detection means for detecting the temperature of the tube wall surface of a fluorescent lamp, and a variable control of the tube current of the fluorescent lamp based on the detection result of the temperature detection means. The present invention is characterized by comprising tube current control means.

Embodiments Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 1 is a circuit diagram of a first embodiment in which the fluorescent lamp device of the present invention is applied to a meter display of a vehicle.

In FIG. 1, the positive side of a power source 10 is connected to the input side of an inverter circuit 14 as a tube current control means via an ignition switch 12, and this in/seater circuit 1
A fluorescent lamp 16 is connected to the output side of 4. A temperature sensor 2° serving as a temperature detecting means is fixed to the surface of the fluorescent lamp 16 via a heat transfer material 18.

The inverter circuit 14 includes a temperature-voltage conversion circuit 22 which inputs the detection signal of the temperature sensor 20, and a voltage output from the /ξ pulse oscillation circuit 24 corresponding to the output voltage 100 of the temperature-voltage conversion circuit 22. Guls's duty ratio (hereinafter abbreviated as τ/T).

where τ: pulse width, ']': ,Ii' pulse period)
A τ/T control circuit 26 that controls the τ/T control circuit 26, a transistor 28 that receives the output 102 of the τ/T control circuit 26 and becomes conductive, and a primary winding 30a connected to the ignition switch 1.
2 and a transformer 3o which is connected between the collector of the transistor 28 and whose secondary winding 30b is connected to the fluorescent lamp 16 via a capacitor 34.

The first embodiment of the present invention has the above configuration, and its operation will be explained below. When a power supply voltage is applied from the power supply lO to the primary winding 308 of the tiger 77300 via the ignition switch 12, the output 102 of the τ/T control circuit 26 causes the transistor 28 to turn ON-OF'F. A current is intermittently applied to the secondary winding 30a, and a high frequency voltage induced in the secondary J@ line 30bK is supplied to the fluorescent lamp 16.

The fluorescent lamp 16 has mercury sealed inside the tube, but since the mercury vapor pressure inside the tube changes depending on the temperature, the efficiency of generating ultraviolet rays for excitation of the fluorescent substance also changes. For this reason, as shown in FIG. 2, especially at low temperatures, the luminance of the fluorescent lamp 16 is low (as the temperature increases, the degree of °ChL increases).

However, the present invention detects the tube wall temperature which is correlated with the temperature inside the fluorescent lamp tube as described above, and inputs this detection result to the τ/T control circuit 26 via the temperature-voltage conversion circuit 22. . This τ/T flilJ control circuit 26 is the pulse oscillation circuit 2
The τ/T ratio of the pulse output from 4 is controlled in accordance with the output voltage 100 of the temperature-voltage conversion circuit 22, and this τ
In order to turn on and off the transistor 28 with the pulse signal 102 whose /T ratio is controlled, the transformer 30 generates the high frequency voltage 104 required for the fluorescent lamp 16, and
The tube current 106 flowing through the tube 6 is controlled to a large amount when the temperature is low and to a small amount when the temperature is high. As a result, as shown in FIG.
．． It is possible to automatically correct the characteristic that the 0 emission luminance changes significantly depending on the temperature to within a predetermined appropriate range.

FIG. 4 is a circuit diagram showing a second embodiment of the present invention, in which the same parts as in FIG. 1 are denoted by the same reference numerals. A voltage power supply 32 is provided, and the output of the constant voltage power supply 32 is variably controlled via the temperature-voltage conversion circuit 22 in accordance with the tube wall temperature of the fluorescent lamp 16, so that the temperature characteristics of the luminance of the fluorescent lamp 16 are adjusted to the third temperature. The correction is made as shown in the figure.

Effects of the Present Invention As described above, according to the present invention, the dependence of the luminance of the fluorescent lamp on the ambient temperature is eliminated. For example, when the fluorescent lamp device of the present invention is applied to a vehicle meter display, Since it is possible to estimate i% of the luminescence of the fluorescent lamp when the engine is started, the readability of the display can be improved when a fluorescent lamp is used as the light source for illuminating the meter. In addition, when a fluorescent lamp is turned on for a long time, the luminance increases due to the fluorescent lamp's self-heating, but since the luminance can be precisely controlled, effects such as being able to adjust the display brightness at night to an appropriate value can be obtained. .

Although the illustrated example shows the fluorescent lamp device of the present invention applied to a vehicle meter display, it can also be applied to a case where a fluorescent lamp is used as a narrow light source such as an indoor light, a headlamp, etc. Characteristics can be improved.

[Brief explanation of the drawing]

Figure 81!1 is a circuit diagram showing the 1''A embodiment of the fluorescent lamp device of the present invention, Figure 2 is a diagram showing the relationship between temperature and luminance due to the tilting of a conventional fluorescent lamp installation, and Figure 3 is a diagram showing the relationship between temperature and luminance according to the conventional fluorescent lamp installation tilt. FIG. 4 is a diagram showing the relationship between temperature and luminance of light emitted by the fluorescent lamp device of the invention, and FIG. , 10... Power source, 12.°° ignition switch, 14... Innovative circuit, 16... Fluorescent lamp, 18... Heat transfer material, 20... Temperature sensor, 22... - Temperature-voltage conversion circuit, 24... Pulse oscillation circuit, 26... Duty ratio control circuit, 28... Transistor, 30... Transformer, 32... Constant voltage power supply, 34... Capacitor. Agent: Patent attorney Yoshi 1) Kenji (1 other person) Figure 1 Figure 2

Claims (1)

[Claims] (1) Temperature detection means for detecting the tube wall surface temperature of the fluorescent lamp;
A fluorescent lamp device comprising: tube current control means for variably controlling the tube current of the fluorescent lamp based on the detection result of the temperature detection means.