JPH04106896A - Lighting device - Google Patents

Abstract

PURPOSE:To obtain a stable discharge start of a CFL even in the dark by providing an auxiliary light source near a discharge electrode of the CFL. CONSTITUTION:A miniature electric bulb 1 is provided as an auxiliary light source near a discharge electrode 2 of a cold cathode discharge tube (CFL) and the electric bulb 1 is lighted by impressing a DC voltage. Consequently, the CFL, which does not start discharge entirely or takes more than several seconds before a discharge start, instantly starts discharge. As the auxiliary light source, a light source such as a light emitting diode excluding the miniature electric bulb 1 can be used. Accordingly, a stable and instantaneous discharge start can be obtained even in the case where any factor to become a trigger for discharge start such as outer light can not be expected in the darkness.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a lighting device using cold cathode discharge tubes.

[Conventional technology]

An example of a lighting device using a conventional cold cathode discharge lamp (hereinafter referred to as CFL) is shown in FIG.

As shown in this figure, in the conventional lighting device, the periphery of the CFL 3 is covered with a reflector 6, a diffuser 4, etc.
It has a structure that is almost completely blocked from external light.

[Problem to be solved by the invention]

The discharge of a CFL starts when a voltage of several hundred volts is applied to the discharge electrodes at both ends of the CFL, and the initial electrons generated in the discharge tube move when triggered by external light, generating a current. However, as explained in the previous section, conventional lighting devices have a structure in which the CFL is surrounded by a reflector, etc., and as a result, external light, etc., which triggers the start of discharge, is becomes difficult to enter,
The problem was that the discharge did not start.

The present invention is intended to solve these problems, and its purpose is to enable CFLs to operate stably and instantaneously even in the dark and when elements such as external light that will trigger the start of discharge cannot be expected. An object of the present invention is to provide a lighting device that can initiate discharge.

[Means to solve the problem]

The lighting device of the present invention uses a cold cathode discharge tube as a means for illuminating an electro-optical element such as a liquid crystal display device, and is characterized in that an auxiliary light source is provided near the discharge electrode of the cold cathode discharge tube. .

[Effect]

By installing an auxiliary light source near the CFL discharge electrode, the CF
When L cannot obtain a trigger element such as external light at the time of starting discharge in the dark, the CFL uses the light from the auxiliary light source as a trigger.
starts discharging.

[Example 1] FIG. 1 is a diagram showing the structure of a lighting device in Example 1 of the present invention.

As shown in the figure, a miniature light bulb 1 is installed as an auxiliary light source near the CFL discharge electrode 2 (in this embodiment, approximately 6 mm away from the discharge electrode), and a voltage of 1.5 V DC is applied to the light bulb. and turned on the light.

As a result, CFLs that did not start discharging at all or took several seconds or more to start discharging started instantaneously (within 1 second).

Although a miniature light bulb is used as the auxiliary light source in this example,
It should be noted that the same effect can be obtained by using other light sources such as light emitting diodes.

[Example 2] In the above-mentioned Example 1, since the miniature light bulb serving as the auxiliary light source is always on, problems arise when commercializing the light bulb, such as an increase in the life span of the light bulb and an increase in power consumption.

Here, it is theoretically possible to predict that the auxiliary light source only needs to be turned on until the CFL starts discharging, and that the effect will not change even if the CFL starts discharging and then turns off.
In addition, it was confirmed that even if the auxiliary light source was turned off after the CFL started discharging, it had no effect on the CFL discharge.

Therefore, in the second embodiment, the lighting time of the miniature light bulb as the auxiliary light source was set to the minimum necessary period. The specific method is shown below.

In Example 2, the lighting time of the auxiliary light source was set to the moment the CFL started discharging.

FIG. 2 is a configuration diagram of a lighting device according to a second embodiment.

As shown in the figure, focusing on the fact that the input current of the CFL lighting device 11 increases when the CFL lights up, a signal 9 for controlling the lighting of the auxiliary light source is created by the input current sensing circuit 10 based on the change in the input current. , the drive circuit 12 that turns on and off the auxiliary light source is turned on and off using the control signal.

By lighting the auxiliary light source only during the necessary period in this manner, it was possible to suppress an increase in power consumption outside the necessary period and a reduction in the life of the auxiliary light source.

In this embodiment, the method of controlling the turning on and off of the auxiliary light source was performed by sensing the change in the input current of the CFL lighting device, but it is also possible to use a charging conversion element that senses the light when the CFL starts discharging, for example. Other methods may be used, such as creating a control signal.

〔Effect of the invention〕

As described above, according to the present invention, in a lighting device using a CFL, by providing an auxiliary light source near the discharge electrode of the CFL, stable discharge initiation of the CFL can be obtained even in darkness, and an auxiliary light source is not required. By setting the lighting period to a minimum, it is possible to extend the life of the auxiliary light source and achieve low power consumption.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a lighting device in Example 1 of the present invention. FIG. 2 is a configuration diagram of a lighting device according to a second embodiment of the present invention. FIG. 3 is a diagram showing the structure of a conventional lighting device. 1. Auxiliary light source (small light bulb) 2. CFL discharge electrode 3. CFL (cold cathode discharge tube) 4. Diffusion plate 5. Light guide 6. Reflection plate 7. Upper case lower case control signal Input current sensing circuit CFL lighting device auxiliary light source drive circuit Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki and 1 other person Figure 2 Figure 1

Claims (3)

[Claims] (1) A lighting device using a cold cathode discharge tube as a means for illuminating an electro-optical element such as a liquid crystal display device, characterized in that an auxiliary light source is provided near the discharge electrode of the cold cathode discharge tube. (2) Claim 1, wherein the auxiliary light source emits light at least for a period until the cold cathode discharge tube starts discharging.
Lighting device as described. (3) Claim 1 characterized in that the auxiliary light source detects that discharge of the cold cathode discharge tube has not started and emits light.
Lighting device as described.