JPS62234185A - Lighting apparatus for fluolescent lamp - 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] Ma3 Sat (') J! l]-Sat! The present invention relates to an illumination device mainly for a flat panel type fluorescent lamp used as a backlight for a liquid crystal display panel.

The backlight of the LCD panel used for image display in LCD TVs requires a surface-emitting light source with a uniform brightness distribution, and EL is commonly used for this type of light source. There are lighting bodies for lamps and flat panel fluorescent lamps. EL lamps have the advantage of low power consumption (and a uniform brightness distribution), but they have technical problems such as the brightness being much lower than fluorescent lamps and the inability to produce good white color, which is why recent LCD TVs At present, it is not possible to keep up with the demands for more color and larger sizes.On the other hand, the illumination body for fluorescent lamps is, for example, a flat container consisting of a diffusely reflecting surface and a diffusely transmitting plate facing each other. Because it is capable of emitting surface light with high brightness and a nearly uniform brightness distribution, it is widely used not only as a backlight for liquid crystal display panels, but also for other general indicator lights and illumination lights. In addition, this illumination body for fluorescent lamps uses fluorescent lamps with emission spectra in the three wavelength ranges of blue, green, and red, and selects the light from the fluorescent lamps with blue, green, and red light filters. By transmitting light, it can be effectively used as a backlight for color liquid crystal display panels, and research and development are underway to make color liquid crystal televisions a reality.

Such illumination bodies for fluorescent lamps have been put into practical use as backlights for liquid crystal display screens of about 2 to 3 inches, and examples are shown in Figures 5 and 6. To explain, (1) is a rectangular reflection plate made of resin or the like, and the bottom surface is formed as a diffuse reflection surface (2). (3) is a rectangular diffuse transmission plate fixed to the upper end opening of the reflection plate (1), and together with the reflection plate (1) forms a flat panel type container (4). (5) is a container (4)
A straight tube fluorescent lamp is housed in a tube, and its light emitting part is placed between a diffuse reflection surface (2) and a diffuse transmission plate (3).

When the fluorescent lamp (5) is turned on, a portion of the light is directly transmitted through the diffuse transmission plate (3) through repeated diffusion, and the remaining light is diffusely reflected on the diffuse reflection surface (2) and is diffusely transmitted. Board (
3), and as a result, the light that has passed through the diffuse transmission plate (3) has a nearly uniform brightness distribution, and the light that has passed through the diffuse transmission plate (3) has an almost uniform brightness distribution, and is displayed on a liquid crystal display panel (
6) Illumination.

A liquid crystal television equipped with a liquid crystal display panel (1) that uses the fluorescent lamp illumination body (7) as a backlight is small, lightweight, and convenient to carry, so a portable type that can be powered by dry batteries is preferred. It has been awarded a prize, and there,
The lighting circuit for the fluorescent lamp (5) of the illumination body (7) uses a low power consumption circuit that can be lit for a long time using dry batteries.
For example, an inverter circuit (8) as shown in FIG. 7 is used. This inverter circuit (8) includes an oscillation transformer (T), a resistor (Rt) (R
It consists of two transistors (Trl) (Tr2) connected in a push-pull manner via a capacitor (C) and a capacitor (C).

When the DC voltage of the dry battery (9) is applied to this inverter circuit (8), both transistors (Trl) (Tr2) alternately turn on and off, causing the oscillation transformer (T) to oscillate and A high frequency voltage is generated, which lights up the fluorescent lamp (5) in high Jm waves.

The dry cell batteries used as a power source for portable LCD televisions that can be powered by dry cell batteries are equivalent to about six 1.5 V 11 batteries. Fluorescent lamps (5
) for a long time, the total power consumption of the fluorescent lamp (5) and the inverter circuit (8) is required to be less than, for example, IW/H. This requirement applies if the display surface of the LCD TV is as small as 2 inches.
Relatively easy to achieve. However, the display surface of recent LCD TVs is becoming increasingly larger from 2 inches to 3 inches to 4.5 inches, and in response to this trend, larger lighting bodies for flat panel fluorescent lamps are being used. requested. Therefore, as a way to meet this demand, it is possible to use curved fluorescent lamps with long arc lengths such as S-shaped fluorescent lamps, and to use multiple straight tube fluorescent lamps with short arc lengths arranged in parallel. It is possible that However, fluorescent lamps have a long arc length (which increases power consumption, making it difficult to run on batteries for long periods of time), and when multiple fluorescent lamps are used to light the lamp, power consumption increases significantly. Therefore, there is a problem in that dry cell battery operation cannot be expected for a long time, and this is one of the factors that makes it difficult to commercialize large-sized portable liquid crystal televisions.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a lighting device for a fluorescent lamp of a low power consumption type capable of being driven by a dry battery for a long time and which can sufficiently cope with the increase in the size of a portable liquid crystal television.

11　　　　to do.

The present invention has achieved the above object by providing an illumination body in which a plurality of fluorescent lamps are arranged on the non-liquid crystal panel side of a diffuser-transmitting plate, and in which the plurality of fluorescent lamps are selectively turned on in sequence, and the emission intensity of the lit fluorescent lamps is reduced. This is achieved by a lighting device for a fluorescent lamp that includes a lighting circuit including a sequential lighting control unit that lights the next fluorescent lamp scheduled to be lit at a timing when the fluorescent lamp is in a decay state.

By selecting the number of fluorescent lamps in the rough illumination body, it is possible to sufficiently cope with the increase in the size of the liquid crystal display panel, and by turning on multiple fluorescent lamps in sequence, a low IR power type can be realized. be done. In addition, by sequentially lighting a plurality of fluorescent lamps and partially overlapping the lighting start-up period of the next fluorescent lamp with the light emission decay period of the lit fluorescent lamp, the illumination body emits light from a surface without flickering.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3. In FIGS. 1 and 2, (10) is a flat panel type container, and a rectangular diffuse-transmitting plate (13) is placed on a rectangular dish-shaped reflector plate (12) having a diffuse-reflecting surface (11) on the inner surface. It is covered and fixed. (Ll) (Lx)
. . . are a plurality of, for example, four, first to fourth straight tube fluorescent lamps housed in a container (10), each of which has a diffuser transmission plate (1
3) are arranged parallel to each other at regular intervals on a plane parallel to . Both ends of each fluorescent lamp (Ll) to (L4) are electrode housing parts that hardly contribute to light emission, and these ends are removed from the required light emitting part [main reflective surface part of the diffuse reflective surface] of the container (10). A flat panel illumination body (14) is configured by housing the fluorescent lamps (Ll) to (L4) in a container (10).
(15) is a lighting circuit for blinking each fluorescent lamp (Ll) to (L4), which includes the first to fourth fluorescent lamps (Lt) to
Sequential lighting 1i1 that selectively controls blinking of (L4) sequentially
1fa! 1 part (16).

The illumination body (14) is used, for example, as a backlight for a liquid crystal display panel (17) of a liquid crystal television shown by the chain line in FIG. By using four first to fourth fluorescent lamps (Ll) to (L4), such an illumination body (14) has an increased light emitting area, which makes it possible to increase the size of the liquid crystal display panel (17). be able to cope with it adequately. It is also possible to light the first to fourth fluorescent lamps (Ll) to (I, 4) using a commercial AC power supply; )～(L
By sequentially turning on the lights 4), less power is required, and therefore, it is also possible to turn on the lights using an inverter using a DC power source from a dry battery.A specific example of this will be described below.

The lighting circuit (15) includes first to fourth fluorescent lamps (Ll) to (
The first to fourth inverter circuits (11) to (I4) that independently light up L4) at high frequency, and each inverter circuit (11)
~ (I4) consists of a sequential lighting control section (16) that sequentially applies a DC voltage from a dry battery (18) at a fixed cycle, and the sequential lighting control section (16) is configured to apply the DC voltage of a dry battery (18) to (I4) sequentially at a constant cycle. As shown in the figure, the first to fourth fluorescent lamps (LL) to (L4)
The lights are controlled to turn on one by one by partially overlapping their emitting magnetism. That is, the sequential lighting control unit (16) first sends a lighting signal to the first inverter circuit (11) to light the first fluorescent lamp (Ll) for a predetermined short time T, and the first fluorescent lamp (Ll) lights up. do. At a predetermined time 11 of the decay period from when the emission intensity of the first fluorescent lamp (Ll) starts to decay until it is completely turned off, the lighting control section (16) sequentially switches the light emission intensity of the first fluorescent lamp (Ll) to the second
A lighting signal is output to the inverter circuit (I2), and the second
The fluorescent lamp (Ll) is lit for a predetermined time T from time 11, and the lighting startup period of the second fluorescent lamp (Ll) and the lighting M decay period of the first fluorescent lamp (Lt) overlap. Similarly, the second
During the lighting decay period of the fluorescent lamp (Ll), the third fluorescent lamp (L
3) is lit, the fourth fluorescent lamp (L4) is lit at time L2 during the lighting capital reduction period of the third fluorescent lamp (L8), and,
The first fluorescent lamp (Ll) is turned on during the lighting decay period of the fourth fluorescent lamp (L4), and thereafter the above-described blinking operation is repeated. Therefore, the light emission waveform on the light emitting surface of the illumination body (14) becomes a continuous waveform as shown in waveform (a) in Fig. 3, and the first to fourth fluorescent lamps (Ll) to (L4) are sequentially Even when blinking, a good surface-emitting light source with no flicker can be obtained.

Incidentally, it is possible to sequentially turn on the first to fourth fluorescent lamps (Lr) to (L4) by turning on the next one at the timing when one lamp is turned on and turned off, but as mentioned above, each fluorescent lamp Sequential lighting in which the phases of the emission waveforms are overlapped little by little allows for a lighting object that emits surface light with higher brightness and less flicker.

Furthermore, the fluorescent lamp used in the present invention is not limited to the straight tube type, and for example, as shown in FIG.
U-shaped fluorescent lamps (Ls) and (La) may be housed, and these two lamps may be sequentially turned on by a lighting circuit (15°) with the phases of their emission waveforms slightly overlapping. in this way,
When U-shaped fluorescent lamps (Ls) (La) are used, the number of fluorescent lamps used for a container of a predetermined size can be reduced, which is advantageous in terms of cost.

Further, the present invention is not limited to being driven by dry batteries.

Further, in the present invention, the illumination body is not limited to a diffuse transmitting plate, a diffuse reflecting surface, and a fluorescent lamp, but can also be composed of a diffuse transmitting plate and a fluorescent lamp, and its form is not limited to a flat panel type container.

According to the present invention, it is possible to fully cope with the increase in the size of the liquid crystal display panel, and by sequentially lighting up a plurality of fluorescent lamps of the illumination body with the phases of their emission waveforms slightly overlapping. A high brightness, low power consumption type surface light source can be obtained, and a lighting device can be provided which is particularly effective as a backlight for a liquid crystal display panel of a portable liquid crystal television.

[Brief explanation of drawings]

Fig. 1 is a schematic plan view showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, and Fig. 3 shows the light emission of the fluorescent lamp and illumination body in the device shown in Fig. 1. FIG. FIG. 4 is a schematic plan view showing another embodiment of the present invention. FIG. 5 is a plan view of an illumination body in a conventional fluorescent lamp illumination device, FIG. 6 is a sectional view taken along line B-B in FIG. 5, and FIG.
This figure is a lighting circuit diagram of a fluorescent lamp in the illumination body of FIG. 5. (10)・-Container, (Lri~(La)...-Fluorescent lamp, (14)・-・
Illumination body, (15) --- lighting circuit.

Claims (1)

[Claims] (1) An illumination body in which a plurality of fluorescent lamps are arranged on the non-liquid crystal panel side of a diffuse transmission plate, and a timing when the plurality of fluorescent lamps are selectively turned on in sequence and the emission intensity of the lit fluorescent lamps is in an attenuated state. 1. A lighting device for a fluorescent lamp, comprising: a lighting circuit including a sequential lighting control unit that lights the next fluorescent lamp scheduled to be lit.