JP3279489B2 - LCD lighting system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device for a liquid crystal for illuminating a transmission type liquid crystal display panel from the rear.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have attracted attention for their characteristics of low power consumption, thinness and light weight. For example, instead of cathode ray tubes, they have been rapidly spreading to application fields such as monitors for consumer images and monitors for industrial equipment. A wide variety of products whose parts are liquid crystal have been developed.

There are two types of liquid crystal display devices: a reflection type liquid crystal display device which reflects natural light to view an image because the liquid crystal itself does not emit light, and a transmission type liquid crystal display device which illuminates an image with a backlight to view the image. Further, the backlight of the oversized liquid crystal display device is classified into an edge type (edge light type flat light) and a direct type backlight. The edge type is thin and has high luminance and high efficiency, and is therefore frequently used as a flat light source. .

FIG. 19 is a cross-sectional view showing the structure of a conventional liquid crystal lighting device. As shown in FIG. 19, the liquid crystal lighting device of Conventional Example 1 has a light guide plate 103 having a diffusion pattern formed or printed on the lower surface thereof, a reflection sheet 104 disposed below the light guide plate 103, and a light guide plate 103 above the light guide plate 103. Is provided with a diffusion plate 105. One fluorescent tube (cold-cathode tube) 101 is arranged near the light-entering portion on the end face of the light guide plate 103, a reflector 102 is arranged outside the fluorescent tube 101, and the transmission-type liquid crystal display panel 1
06 is arranged.

FIG. 20 is a front view showing the arrangement of a fluorescent tube and a light guide plate of the liquid crystal lighting device of the first prior art. As shown in FIG. 20, the light emitted from the fluorescent tube 101 is reflected by the reflecting plate 102 and is incident on the light incident portion on the end face of the light guide plate 103, and the light incident on the reflecting sheet 104 is perpendicular to the traveling direction. Then, the light is emitted from the light emitting surface as plane light, and is further converted into scattered light by the diffusion plate 105, and then the rear part of the transmission type liquid crystal display panel 106 is illuminated.

FIG. 21 is a distribution diagram showing a light emission distribution of the illumination device for a liquid crystal of the first conventional example. As shown in FIG. 21, when a fluorescent tube 101 shorter than the length of the light incident portion of the light guide plate 103 is disposed as a backlight of the transmission type liquid crystal display device, the light emission luminance at both ends near the light incident portion of the light guide plate 103. Is greatly reduced, and the uniformity of light emission luminance is impaired. For this reason, it is necessary to configure the light emission length of the fluorescent tube to be equal to the length of the light incident portion of the light guide plate.

FIG. 22 is a cross-sectional view showing the structure of a conventional example 2 of a liquid crystal lighting device. As shown in FIG. 22, the liquid crystal display device of Conventional Example 2 has a fluorescent tube 101 at the center of a reflection box 107.
Are disposed, a diffusion plate 105 is disposed thereon, and a transmission type liquid crystal display panel 106 is disposed thereon.

FIG. 23 is a front view showing an arrangement of a fluorescent tube and a box-shaped reflecting portion of the liquid crystal lighting device of the second prior art. As shown in FIG. 23, light emitted from the fluorescent tube 101 is reflected by the reflection box 107 and converted into scattered light by the diffusion plate 105, and illuminates the rear part of the transmission type liquid crystal display panel.

FIG. 24 is a distribution diagram showing a light emission distribution of the liquid crystal lighting device of the second conventional example. As shown in FIG. 24, when a fluorescent tube 101 shorter than one side is disposed at the center of a reflection box 107 as a backlight of a transmission type liquid crystal display device,
The distribution in which the light emission luminance is greatly reduced at both ends at the center of the reflection box 107 is reduced, and the uniformity of the light emission luminance is deteriorated. For this reason, the light emission length of the fluorescent tube needs to be set to the length of one side of the reflection box.

[0010]

However, as the size of the liquid crystal display device increases, one side of the light-entering portion or the box-like reflecting portion of the light guide plate becomes longer, and a fluorescent tube having a longer light emission length has been designed. However, there has been a problem that the elongated tubular fluorescent tube is warped and difficult to manufacture in terms of strength, or lacks mass productivity. Further, when the light emission length of the fluorescent tube is increased, the inverter voltage for lighting the fluorescent tube increases, so that it is necessary to increase the voltage output of the inverter circuit. For this reason, it is necessary to configure the lighting device with high withstand voltage components, which causes a problem that the lighting device becomes large and hinders downsizing of the liquid crystal display device.

FIG. 25 is a circuit diagram showing a voltage supply to the fluorescent tube terminal of the liquid crystal lighting device of the third prior art. As shown in FIG. 25, for example, when a plurality of fluorescent tubes 101 are connected to the side surface of the light guide plate 103, the terminals 101 a of the fluorescent tubes 101
Has a low-voltage side inverter voltage (GND), and a terminal 101b.
Is supplied with an inverter voltage on the high voltage side via a DC cut capacitor 101c, and an inverter voltage supplied to each terminal of an adjacent fluorescent tube is supplied in order of a low voltage and a high voltage. The potential difference between the terminals 101a and 101b is always high, and there is a problem that light emission flicker occurs due to leakage current between the ends. In addition, since the insulation distance is provided, the distance between the terminals is widened and a dark portion is generated at the joint, so that a uniform high-luminance light emitting surface cannot be obtained.

As a large-sized liquid crystal lighting device, for example, two or more cold-cathode tubes (fluorescent tubes) are provided on the side surface of a light guide plate.
(See Japanese Patent Application Laid-Open No. 6-348213) has been proposed in which the cold-cathode tubes are joined in the longitudinal direction, and the angle between the cold cathode tubes is less than 180 degrees. However, in any case, a dark portion is generated at the joint of the cold cathode tubes, so that the light guide plate is formed in a rectangular shape by dividing the non-light emitting portion including the dark portion and the light emitting surface which emits light uniformly. Therefore, the light guide plate needs to be made larger than necessary, which hinders the miniaturization of the liquid crystal display device.

The present invention has been made in view of the above circumstances, and for example, as a backlight for a large liquid crystal display panel,
An object of the present invention is to provide a liquid crystal lighting device in which a plurality of fluorescent lamps having a short tube length with good productivity are connected in series in a row, and a uniform and high-luminance light-emitting surface can be efficiently and compactly formed over a wider range.

[0014]

SUMMARY OF THE INVENTION The present invention provides a plurality of fluorescent tubes, an end face serving as a light receiving portion for receiving the light emitted from the plurality of fluorescent tubes, and a light emitting surface for converting the received light into plane light and emitting light. And a plurality of fluorescent tubes connected in series in the longitudinal direction in the vicinity of the light incident portion in a plurality of rows , and the plurality of rows are connected in series.
When wiring the voltage supply line to each end of the
Alternately so that terminals are at low voltage or high voltage
A lighting device for a liquid crystal , wherein wiring is performed and terminals of adjacent fluorescent tubes are arranged in a staggered manner.

In the present invention, the fluorescent tube is a cold cathode tube utilizing a glow discharge with a high-voltage AC waveform,
Since the electrode is made of plate or cylindrical metal,
The pipe diameter can be reduced. The fluorescent tube has a tube diameter of, for example, 2 to 4 mm and a length of, for example, 200 to 4 mm.
It is formed of 500 mm, and is used for two or more types of fluorescent tubes, and the ends of adjacent fluorescent tubes are arranged in a staggered manner.
As a material of the light guide plate for introducing light, an acrylic polymer such as polymethyl methacrylate and methacryl styrene copolymer having high transmittance, polycarbonate, and the like are used.

According to the present invention, since the terminals (seam portions) of the fluorescent tubes are arranged in a staggered manner, the non-light-emitting portions of the fluorescent tubes are complemented by the light-emitting portions of the other fluorescent tubes, and the darkness of the light guide plate is reduced. The number of portions is reduced, and a uniform high-luminance light emitting surface can be formed over a wider range. In addition, fluorescent lamps
When wiring a voltage supply line to each end, connect each end of the fluorescent tube
Are alternately arranged so that the low voltage or high voltage
Leakage due to the potential difference at each end tube of the fluorescent tube
Current is reduced, flicker of light can be prevented, and
Since the insulation distance between the parts can be shortened,
The dark area becomes smaller and a light emitting surface with uniform brightness over a wider area
Can be formed.

The total length of a plurality of fluorescent tubes connected in series in the longitudinal direction in the vicinity of the light incident portion is configured to be the length of the light incident portion in the longitudinal direction. According to the above configuration, it is possible to manufacture a liquid crystal lighting device that matches the size of the transmission type liquid crystal display panel.

[0018] The light incident portion may be constituted by one or more end faces of the light guide plate. According to the configuration, by making the light incident portion of the light guide plate a plurality of end surfaces from one end surface,
The dark portion of the light guide plate is reduced, and a more effective uniform high-luminance light emitting surface can be formed.

[0019]

According to another aspect of the present invention, a plurality of fluorescent tubes, an end surface serving as a light receiving portion for receiving light emitted from the plurality of fluorescent tubes, and a light emitting surface for converting received light into plane light and emitting light are provided. A plurality of fluorescent tubes are connected in series in the longitudinal direction in the vicinity of the light-entering portion, and when wiring a voltage supply line to each terminal of the connected fluorescent tubes, A lighting device for a liquid crystal is provided, wherein each end is alternately wired so as to have a low voltage or a high voltage. According to the present invention, even if fluorescent tubes are arranged in a row on the end surface of the light guide plate, the insulation distance between the end portions can be reduced, so that the dark portion is reduced, and a light emitting surface with uniform luminance over a wider range is provided. Can be formed. In addition, flicker of light emission of the fluorescent tube can be prevented.

According to another aspect of the present invention, a plurality of fluorescent tubes for illuminating the rear portion of the transmissive liquid crystal display panel, the plurality of fluorescent tubes are housed, and the emission of the plurality of fluorescent tubes housed is totally reflected. A reflection box in the form of a box, and a diffusion plate that converts the light reflected from the entire surface into scattered light and emits light, and a plurality of fluorescent tubes are serially arranged in series at the center of the reflection box. ,
Wiring voltage supply lines to each end of multiple rows of fluorescent tubes
In this case, the terminals of adjacent fluorescent tubes are
A lighting device for a liquid crystal is provided , wherein the wirings are alternately arranged so as to be adjacent to each other , and the terminals of adjacent fluorescent tubes are arranged in a staggered manner.

In the present invention, in the center of the reflection box,
The total length of a plurality of fluorescent tubes arranged in series in a row is one of the reflector box.
It is preferable to configure the length of the side.

According to the present invention, since the joint portions of the fluorescent tubes are arranged in a staggered manner, the non-light-emitting portions of the fluorescent tubes are complemented by the light-emitting portions of the other fluorescent tubes, and the dark portions of the reflection box and the diffusion plate are darkened. Thus, a more effective uniform high-luminance light emitting surface can be formed. Further, since the insulation distance between the terminals of the fluorescent tube can be reduced, the dark portion of the joint is reduced accordingly. In addition, it is possible to manufacture a liquid crystal lighting device that matches the size of the transmission type liquid crystal display panel.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. Note that the present invention is not limited by this.

FIG. 1 is a sectional view showing the structure of a liquid crystal lighting device according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a fluorescent tube (cold-cathode tube) utilizing glow discharge with a high-voltage AC waveform, and its electrode is made of a plate-like or cylindrical metal, so that the tube diameter can be reduced. . The fluorescent tube has a tube diameter of, for example, 2 to 4 mm, and a length of, for example, 200 to 500 mm. Reference numeral 2 denotes a reflector for reflecting and condensing the light emitted from the fluorescent tube 1, and is made of, for example, white PET.

Reference numeral 3 denotes a light guide plate for introducing light, which is composed of an end face of a light entering portion for introducing light and a light emitting surface for emitting plane light. As a material of the light guide plate, for example, acrylic, polycarbonate, or the like having a high transmittance is used. Reference numeral 4 denotes a reflection sheet that reflects light emitted from the light guide plate 3 toward the light emitting surface, and is made of, for example, PET in which a white pigment is dispersed.
Reference numeral 5 denotes a diffusion plate for diffusing light emitted from the light-emitting surface of the light guide plate 3.
T, composed of polycarbonate. Reference numeral 6 denotes a transmission type liquid crystal display panel for illuminating an image with a backlight and viewing the image.

In the illumination device for a liquid crystal according to the first embodiment, a reflection sheet 4 is arranged below a light guide plate 3, and a plurality of fluorescent tubes 1 shorter than the length of the light entrance portion are serially arranged near the light entrance portion of the light guide plate 3. The reflection plate 2 is arranged outside the plurality of connected fluorescent tubes 1, and the diffusion plate 5 is arranged on the light guide plate 3. The transmission type liquid crystal display panel 6 is disposed thereon.

FIG. 2 is a front view showing the arrangement of the fluorescent tube and the light guide plate of the liquid crystal lighting device of the first embodiment. As shown in FIG. 2, light emitted from the fluorescent tube 1 is reflected by the reflector 2 and is incident on the light incident portion on the end face of the light guide plate 3. First, the light is emitted from the light emitting surface as plane light, and is further converted into scattered light by the diffusion plate 5, and then the rear part of the transmission type liquid crystal display panel 6 is illuminated. Here, the total length of the fluorescent tubes connected in a row to the end face of the light guide plate 3 is adjusted to be the length of the light incident portion.

FIG. 3 is a circuit diagram showing voltage supply to the fluorescent tube terminal of the liquid crystal lighting device of the present invention. As shown in FIG. 3, when wiring the voltage supply lines to the terminals 1a and 1b of the plurality of fluorescent tubes 1 connected in series, the terminals of the adjacent fluorescent tubes are alternately set to have a low voltage or a high voltage. Wired. Thereby, between the terminals 1a-1a 'of the fluorescent tube or 1b-
The potential difference between 1b 'can be reduced.

The voltage supplied to the terminal of the fluorescent tube is, for example,
Inverter circuit, frequency 30-50KHz, voltage 60
An inverter voltage A of 0 to 1000 Vrms and 1.5 to 3 KVp-p is generated. The side where one voltage supply line of this inverter circuit is short-circuited to the ground (GND) or the liquid crystal drive power supply (Vdd) is called a low voltage supply line. The high voltage supply line is supplied with the inverter voltage A via the DC cut capacitor 1c (see FIG. 4). Further, the low voltage is not limited to 0 V and may be 0 V to several V as viewed from GND (leakage current of about several V can be ignored).

FIG. 4 is a diagram showing a voltage waveform of an inverter supplied to a fluorescent tube terminal of the liquid crystal lighting device of the present invention. FIG. 4A shows a high-voltage side voltage waveform, and the inverter voltage A shown in FIG. 4A is supplied to, for example, the terminals 1b and 1b 'of the fluorescent tube shown in FIG. FIG. 4B shows a low-voltage side voltage waveform, and the inverter voltage C (GN) shown in FIG.
D voltage) are, for example, the terminals 1a and 1 of the fluorescent tube shown in FIG.
a '.

FIG. 5 is a diagram showing voltage waveforms of inverter voltages having different frequencies. As shown in FIG. 5, although the frequencies of the inverters A and B supplied to the fluorescent tube are usually different due to the variation of the fluorescent tube and the inverter, the terminal 1a- of the fluorescent tube is always synchronized by synchronizing the oscillation of the inverter.
The potential difference between 1a 'and 1b-1b' can be reduced. Similarly, the voltage (amplitude) of the inverter may be different, but the instantaneous potential difference is reduced by synchronizing the oscillation.

By alternately arranging the terminals of adjacent fluorescent tubes so that the terminals have low voltage or high voltage, the potential difference between the terminals is small, so that the fluorescent tube current becomes stable.
Leakage current between the terminals is reduced, and flickering of light emission of the fluorescent tube can be prevented. Further, since the insulation distance between the terminals can be reduced, the dark portion of the joint is reduced accordingly.

FIG. 6 is a distribution diagram showing a light emission distribution of the liquid crystal lighting device according to the first embodiment of the present invention. As shown in FIG. 6, even if the fluorescent tubes are arranged in a row on the end face of the light guide plate 3, the insulation distance between the terminals can be reduced, so that the dark portion of the joint of the fluorescent tubes is reduced and the uniformity over a wider area is reduced. It is possible to form a light emitting surface having a high luminance. According to the first embodiment, as the backlight of the large liquid crystal display panel, a plurality of fluorescent lamps having a short tube length with good productivity are used, and there is no flickering of the light emission of the fluorescent tube, and a uniform high-luminance light emitting surface over a wide range. It is possible to provide a liquid crystal lighting device that can be efficiently and compactly configured.

FIG. 7 is a sectional view showing the structure of a liquid crystal lighting device according to Embodiment 2 of the present invention. As shown in FIG. 7, a plurality of fluorescent tubes 1 are arranged in series in the longitudinal direction near the light incident portion. Here, two rows of fluorescent tubes are connected in parallel to the end face. The width of the end face of the light guide plate 3 is formed to be several times or more the width of the light guide plate 103 shown in FIG. Also,
The components are the same as those in FIG.

FIG. 8 is a front view showing the arrangement of a fluorescent tube and a light guide plate of a liquid crystal lighting device according to a second embodiment of the present invention. As shown in FIG. 8, a configuration is shown in which a plurality of fluorescent tubes are serially arranged in a plurality of rows in the longitudinal direction near the light incident portion, and terminals of adjacent fluorescent tubes are arranged in a staggered manner. Therefore, since the terminals of the fluorescent tubes are arranged in a staggered manner, the total length of the fluorescent tubes connected in series is adjusted to the length of the light guide plate 3 by using two types of fluorescent tubes. The inverter voltage is also adjusted by the length of the fluorescent tube. The length of the fluorescent tube may be two or more.

Also, in the front view of FIG. 8, two rows of fluorescent tubes are actually shown in an overlapping manner, but in order to show that the terminals of the fluorescent tubes are staggered, the fluorescent tubes are used here. Are shown shifted. Further, although not shown, similarly to the first embodiment, the terminals of the adjacent fluorescent tubes are alternately wired so that the low voltage or the high voltage is applied. The oscillation of the inverter is also synchronized.

FIG. 9 is a distribution diagram showing the light emission distribution of the liquid crystal lighting device according to the second embodiment of the present invention. As shown in FIG. 9, since the terminals (seam portions) of the fluorescent tubes are arranged in a staggered manner, the non-light emitting portions of the fluorescent tubes are complemented by the light emitting portions of the other fluorescent tubes, and the dark portions of the light guide plate are Thus, a uniform, high-luminance light emitting surface can be formed over a wider area. Example 2
According to this, a plurality of fluorescent lamps of short tube length with good productivity are used as the backlight of a large liquid crystal display panel, and there is no flickering of the light emission of the fluorescent tube, and a uniform, high-luminance light-emitting surface over a wide area is efficiently compacted. And a liquid crystal lighting device that can be configured as described above.

FIG. 10 is a sectional view showing the structure of a liquid crystal lighting device according to Embodiment 3 of the present invention. As shown in FIG. 10, the light incident portion is constituted by one or more end faces of the light guide plate, a plurality of fluorescent tubes are serially arranged in a plurality of rows in the longitudinal direction near the plurality of light incident portions, and adjacent fluorescent tubes are arranged. Are arranged in a zigzag pattern. Here, two rows of fluorescent tubes are connected in parallel to a plurality of end faces. The width of the end face of the light guide plate 3 is formed to be several times or more the width of the light guide plate 103 shown in FIG. The components are the same as those in FIG.

FIG. 11 is a front view showing an arrangement of a fluorescent tube and a light guide plate of a liquid crystal lighting device according to a third embodiment of the present invention. FIG.
As shown in FIG. 2, a plurality of fluorescent tubes are serially arranged in a plurality of rows in the longitudinal direction near a plurality of light entrance portions, and terminals of adjacent fluorescent tubes are arranged in a staggered manner. Therefore, since the terminals of the fluorescent tubes are arranged in a staggered manner, the total length of the continuous fluorescent tubes is adjusted to the length of each end surface of the light guide plate 3 by using fluorescent tubes of several lengths. . The inverter voltage is also adjusted by the length of the fluorescent tube. Furthermore, the oscillation of the inverter is also synchronized.

Also, in the front view of FIG.
Although the fluorescent tubes in the rows are shown in an overlapping manner, the rows of the fluorescent tubes are shifted to show that the terminals of the fluorescent tubes are staggered. Further, although not shown, similarly to the first embodiment, the terminals of the adjacent fluorescent tubes are alternately wired so that the low voltage or the high voltage is applied.

FIG. 12 is a distribution diagram showing a light emission distribution of the liquid crystal lighting device according to the third embodiment of the present invention. As shown in FIG. 12, the terminals (seam portions) of the fluorescent tube are arranged in a staggered manner, and the light incident portion is formed by a plurality of end faces of the light guide plate. Complemented by the light emitting portion of the fluorescent tube, the dark portion of the light guide plate becomes smaller, and a more effective uniform high-luminance light emitting surface can be formed. According to the third embodiment, as a backlight of a large liquid crystal display panel,
By using a plurality of fluorescent tubes having short tube lengths with good productivity, it is possible to provide a liquid crystal lighting device in which the fluorescent tubes do not flicker and the light emitting surface with high luminance that is uniform over a wide area is efficiently and compactly configured. .

FIG. 13 is a sectional view showing the structure of a liquid crystal lighting device according to Embodiment 4 of the present invention. As shown in FIG. 13, a plurality of fluorescent tubes are housed, and a box-shaped reflecting box 7 formed so as to totally reflect the light emitted from the plurality of housed fluorescent tubes, and converts the light totally reflected to scattered light. A plurality of fluorescent tubes 1 are arranged in series at the center of a reflection box 7, a diffusion plate 5 is arranged thereon, and a transmissive liquid crystal display panel 6 is arranged thereon. Is done. Note that in Example 4,
The reflection box 7 can be made of the same material as the reflection plate 2. The other components are the same as those in FIG.

FIG. 14 is a front view showing an arrangement of a fluorescent tube and a box-shaped reflecting portion of a liquid crystal lighting device according to a fourth embodiment of the present invention. In FIG. 14, light emitted from a plurality of fluorescent tubes 1 is reflected by a reflection box 7.
Then, the light is reflected by the diffusing plate 5 and converted into scattered light, and the rear part of the transmissive liquid crystal display panel 6 is illuminated. Here, the total length of the fluorescent tubes provided in a row at the center of the reflection box 7 is adjusted to be the length of one side of the reflection box. Further, although not shown, similarly to the first embodiment, the terminals of the adjacent fluorescent tubes are alternately wired so that the low voltage or the high voltage is applied.

FIG. 14 is a distribution diagram showing a light emission distribution of the liquid crystal lighting device according to the fourth embodiment of the present invention. As shown in FIG. 14, even if fluorescent tubes are arranged in a row in the center of the reflective box 7, the fluorescent tubes are reflected on each surface of the reflective box 7, and the voltage supply shown in FIG. The portion becomes smaller, and a light emitting surface with uniform luminance can be formed over a wider range. According to the fourth embodiment, as the backlight of the large-sized liquid crystal display panel, a plurality of fluorescent tubes having a short tube length with good productivity are used, and there is no flickering of the light emission of the fluorescent tubes, and a uniform, high-luminance light-emitting surface is obtained over a wide range. An efficient and compact liquid crystal lighting device can be provided.

FIG. 15 is a sectional view showing the structure of a liquid crystal lighting device according to Embodiment 5 of the present invention. In FIG. 15, a plurality of fluorescent tubes 1 are connected in series at a central portion of a reflection box 7 in a plurality of rows, a diffusion plate 5 is disposed thereon, and a transmissive liquid crystal display panel 6 is disposed thereon.
Is arranged. In the fifth embodiment, the reflection box 7 can be made of the same material as the reflection plate 2. The other components are the same as those in FIG.

FIG. 16 is a front view showing an arrangement of a fluorescent tube and a box-shaped reflecting portion of a liquid crystal lighting device according to a fifth embodiment of the present invention. In FIG. 16, a plurality of fluorescent tubes are serially arranged in series at the center of the reflection box, and terminals of adjacent fluorescent tubes are arranged in a staggered manner. Here, the total length of the fluorescent tubes connected in a plurality of rows at the center of the reflection box 7 is adjusted to be the length of one side of the reflection box. Although not shown, the first embodiment
Similarly to the above, the terminals of the adjacent fluorescent tubes are alternately wired so as to be at low voltage or at high voltage.

FIG. 17 is a distribution diagram showing the light emission distribution of the liquid crystal lighting device according to the fifth embodiment of the present invention. As shown in FIG. 17, since the terminals (seam portions) of the fluorescent tubes are arranged in a staggered manner, the non-light-emitting portions of the fluorescent tubes are complemented by the light-emitting portions of other fluorescent tubes, and the dark portions of the light guide plate are It is possible to form a light emitting surface with a high luminance and a wider range and more uniformly. According to the fifth embodiment, as the backlight of the large liquid crystal display panel, a plurality of fluorescent lamps having a short tube length with good productivity are used, and there is no flickering of the light emission of the fluorescent tube, and a uniform high-luminance light emitting surface over a wide range. It is possible to provide a liquid crystal lighting device that can be efficiently and compactly configured.

[0049]

According to the present invention, as a backlight of a large liquid crystal display panel, a plurality of fluorescent lamps having a short tube length with good productivity are connected in series in a row, so that a uniform, high-luminance light-emitting surface can be efficiently obtained over a wide range. It is possible to provide a lighting device for a liquid crystal that can be configured well and compactly.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal lighting device according to a first embodiment of the present invention.

FIG. 2 is a front view showing an arrangement of a fluorescent tube and a light guide plate of the liquid crystal lighting device according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a voltage supply to an end portion of a fluorescent tube of the liquid crystal lighting device of the present invention.

FIG. 4 is a diagram showing a voltage waveform of an inverter supplied to a fluorescent tube terminal of the liquid crystal lighting device of the present invention.

FIG. 5 is a diagram showing voltage waveforms of inverters having different frequencies.

FIG. 6 is a distribution diagram illustrating a light emission distribution of the liquid crystal lighting device according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a configuration of a liquid crystal lighting device according to a second embodiment of the present invention.

FIG. 8 is a front view showing an arrangement of a fluorescent tube and a light guide plate of the liquid crystal lighting device according to the second embodiment of the present invention.

FIG. 9 is a distribution diagram illustrating a light emission distribution of the liquid crystal lighting device according to the second embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a configuration of a liquid crystal lighting device according to a third embodiment of the present invention.

FIG. 11 is a front view illustrating an arrangement of a fluorescent tube and a light guide plate of a liquid crystal lighting device according to a third embodiment of the present invention.

FIG. 12 is a distribution diagram illustrating a light emission distribution of the liquid crystal lighting device according to the third embodiment of the present invention.

FIG. 13 is a cross-sectional view illustrating a configuration of a liquid crystal lighting device according to a fourth embodiment of the present invention.

FIG. 14 is a front view showing an arrangement of a fluorescent tube and a box-shaped reflecting portion of a liquid crystal lighting device according to a fourth embodiment of the present invention.

FIG. 15 is a distribution diagram showing a light emission distribution of the liquid crystal lighting device according to the fourth embodiment of the present invention.

FIG. 16 is a cross-sectional view illustrating a configuration of a liquid crystal lighting device according to a fifth embodiment of the present invention.

FIG. 17 is a front view showing an arrangement of a fluorescent tube and a box-like reflecting portion of a liquid crystal lighting device according to a fifth embodiment of the present invention.

FIG. 18 is a distribution diagram illustrating a light emission distribution of the liquid crystal lighting device according to the fifth embodiment of the present invention.

FIG. 19 is a cross-sectional view showing a configuration of a liquid crystal lighting device of Conventional Example 1.

FIG. 20 is a front view showing the arrangement of a fluorescent tube and a light guide plate of the liquid crystal lighting device of Conventional Example 1.

FIG. 21 is a distribution diagram illustrating a light emission distribution of the liquid crystal lighting device of Conventional Example 1.

FIG. 22 is a cross-sectional view illustrating a configuration of a liquid crystal lighting device of Conventional Example 2.

FIG. 23 is a front view showing an arrangement of a fluorescent tube and a box-shaped reflecting portion of the liquid crystal lighting device of Conventional Example 2.

FIG. 24 is a distribution diagram showing a light emission distribution of the liquid crystal lighting device of Conventional Example 2.

FIG. 25 is a circuit diagram showing voltage supply to a fluorescent tube terminal of the conventional liquid crystal lighting device of the third example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluorescent tube 2 Reflection plate 3 Reflection sheet 4 Light guide plate 5 Diffusion plate 6 Liquid crystal display panel 7 Reflection box

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Claims (6)

(57) [Claims] 1. A light guide plate comprising: a plurality of fluorescent tubes; an end surface serving as a light receiving portion for receiving light emitted from the plurality of fluorescent tubes; and a light emitting surface for converting received light into plane light and emitting light. A plurality of fluorescent tubes connected in series in the longitudinal direction in the vicinity of the light incident portion, and a voltage supply line is provided at each end of the fluorescent tubes connected in a plurality of columns.
When connecting, the terminals of adjacent fluorescent tubes are
A lighting device for a liquid crystal display , wherein wirings are alternately arranged so as to have a high voltage, and terminals of adjacent fluorescent tubes are arranged in a staggered manner. 2. The liquid crystal device according to claim 1, wherein the total length of the plurality of fluorescent tubes connected in series in the longitudinal direction near the light incident portion is the longitudinal length of the light incident portion. Lighting equipment. 3. A light guide plate comprising: a plurality of fluorescent tubes; an end surface serving as a light incident portion for receiving light emitted from the plurality of fluorescent tubes; and a light emitting surface for converting the received light into plane light and emitting light. A plurality of fluorescent tubes are connected in series in the longitudinal direction near the light incident portion,
When arranging voltage supply lines at each end of the fluorescent tubes connected in series, the terminals of the adjacent fluorescent tubes are alternately wired so that low voltages or high voltages are connected. . 4. The illumination device for a liquid crystal according to claim 3, wherein the total length of the fluorescent tubes connected in series in the longitudinal direction near the light incident portion is the length in the longitudinal direction of the light incident portion. . 5. A plurality of fluorescent tubes for illuminating a rear part of a transmissive liquid crystal display panel, and a box-like shape formed to house the plurality of fluorescent tubes and to reflect light emitted from the stored plurality of fluorescent tubes over the entire surface. fluorescence and reflection box, and a diffuser which emits light by converting the light entirely reflected scattered light, a plurality of rows communicating with set in series a plurality of fluorescent tubes in the center of the reflector box, in which a plurality of columns continuously provided in Each of the tubes
When wiring the voltage supply line to the end, each terminal of the adjacent fluorescent tube
Are alternately wired so that they are low voltage or high voltage
And the terminals of adjacent fluorescent tubes are arranged in a zigzag pattern. 6. The liquid crystal lighting device according to claim 5, wherein the total length of the plurality of fluorescent tubes connected in series in the central portion of the reflection box is one side of the reflection box. .