JP2008016317A - Backlight device, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight device allowing a fluorescent tube causing luminance degradation to be identified by uniformly measuring luminance values of a plurality of fluorescent tubes; and a liquid crystal display device. <P>SOLUTION: This backlight device includes the plurality of fluorescent tubes 13a-13e, and a rear chassis 11 housing the fluorescent tubes 13a-13e. The rear chassis 11 has openings 20a-20e in the vicinities of the fluorescent tubes 13a-13d, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a backlight device and a liquid crystal display device, and more particularly to a direct type backlight device having a light source directly under a diffusion plate, and a liquid crystal display device having such a backlight device.

  A backlight device is used as a unit that illuminates the liquid crystal display device. There are two types of backlight devices: a direct light method in which a plurality of light sources are arranged directly under a light emitting surface, and an edge light method that guides light from the light source to the light emitting surface using a light guide plate. Compared with edge-light type backlight devices, direct-type backlight devices have the advantage that the light-emitting surface can be easily enlarged and can easily achieve high brightness. It can be particularly preferably used.

  When a fluorescent tube is used as a light source of a backlight device in a liquid crystal display device, the fluorescent tube generally has a shorter life than other components. For this reason, technological development for extending the life of fluorescent tubes is being promoted. However, it is difficult to achieve the same life as other parts. When the life of the fluorescent tube is exhausted, the luminance is extremely lowered or the light is not lit. Leaving a fluorescent tube that has reached the end of its life may lead to a serious failure such as indistinguishable display characters. Therefore, in general, replacement of a fluorescent tube whose life has expired allows it to be used for a long time together with other components of the liquid crystal display device.

  Whether or not the life of the fluorescent tube has expired is detected by measuring the luminance with a luminance measuring sensor. 8 and 9 are diagrams schematically showing a conventional direct-type backlight device, respectively. 8 is a bottom view of the backlight device 100, and FIG. 9 is a cross-sectional view taken along the line I-I 'of FIG. As shown in the drawings, the backlight device 100 generally includes a rear chassis 101, fluorescent tubes 102a to 102e, a reflection sheet 103, and a diffusion plate 104. The fluorescent tubes 102 a to 102 e constitute a light source of the backlight device 100. The rear chassis 101 accommodates the fluorescent tubes 102a to 102e. The diffusion plate 104 is irradiated with direct light from the fluorescent tubes 102 a to 102 e or reflected light from the reflection sheet 103. The diffusion plate 104 is configured as a light emitting surface of the backlight device 100.

  As shown in FIGS. 8 and 9, in the conventional backlight device 100, an opening 110 is provided in the rear chassis 101. The opening 110 is a hole for installing a luminance measurement sensor for measuring the luminance of the backlight device 100, and is provided so as to penetrate the rear chassis 101 at a substantially central portion of the rear chassis 101. Conventionally, a luminance measuring sensor is installed in the opening 103 and the luminance of the backlight device 100 is constantly monitored to detect the state of the fluorescent tubes 102a to 102e, that is, the replacement time.

  The technique described above is disclosed in, for example, Patent Document 1. Patent Document 1 discloses a backlight unit including a double tube discharge lamp, a temperature sensor, a luminance sensor, a liquid crystal display unit, a light guide, and the like. In this backlight unit, an opening is provided in a casing which is a main body of the apparatus, and a luminance sensor is attached to the opening. The brightness sensor measures the brightness of the light guide, and the control means captures the measured value to detect an abnormal state of the arc tube.

JP2002-1000048

  However, in the conventional backlight device as shown in FIGS. 8 and 9 and Patent Document 1, since the luminance of the backlight device is measured only at one location near the opening 110, the fluorescent tube near the opening 110 is used. For example, even if one fluorescent tube other than the vicinity of the opening 110 is cut, it is difficult to detect it. Therefore, there has been a problem that a serious failure may occur, for example, a display tube cannot be distinguished by leaving a fluorescent tube whose life has expired.

  The present invention has been made to solve the above-described problems, and provides a backlight device and a liquid crystal display device that can uniformly detect the occurrence of abnormality in a fluorescent tube by uniformly measuring the luminance of a plurality of fluorescent tubes. The purpose is to do.

  The backlight device according to the configuration of the present invention is a backlight device including a plurality of light sources and a housing member that houses the light sources. The housing member includes openings in the vicinity of at least two of the plurality of light sources. It is characterized by that.

  The opening may be provided in the vicinity of each light source. Further, the opening may be provided immediately below each light source. Each light source may be constituted by a fluorescent tube. Moreover, an opening part may be provided along the direction orthogonal to the longitudinal direction of each light source. The opening may be provided in the vicinity of one end side of each light source. The opening may be provided in the vicinity of the same end side of each light source. The opening may be provided in the vicinity of the end on the side where the adjacent light sources alternate.

  A liquid crystal display device according to a configuration of the present invention includes a liquid crystal panel, a plurality of light sources, and a housing member that houses the light sources, and the housing member includes openings in the vicinity of at least two of the plurality of light sources. With.

  The opening may be provided in the vicinity of each light source. In addition, a luminance measurement sensor that measures the luminance of each light source may be attached to the opening. You may provide the control means which detects abnormality of a light source based on the measured value from each luminance measurement sensor.

  According to this invention, the backlight device includes a plurality of light sources and a housing member that houses the light sources, and the housing member includes openings in the vicinity of at least two of the plurality of light sources. There is an effect that the luminance of a plurality of light sources can be uniformly measured to reliably detect the occurrence of an abnormality in the fluorescent tube.

Embodiment 1 FIG.
Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded perspective view of a backlight device 10 according to Embodiment 1 of the present invention. As shown in FIG. 1, the backlight device 10 includes a rear chassis (housing member) 11, a reflection sheet 12, fluorescent tubes 13 a to 13 e, a lamp support base 14, and a diffusion plate 15. A reflective sheet 12 is disposed on the rear chassis 11, and fluorescent tubes 13 a to 13 e are disposed on the reflective sheet 12. The fluorescent tubes 13a to 13e are supported and fixed from above by the lamp support base 14. A diffusion plate 15 is disposed on the lamp support 14.

  The fluorescent tubes 13 a to 13 e are configured as a light source of the backlight device 10. An AC voltage generally called a lighting start voltage is applied by an inverter 17 to one input terminal of each of the fluorescent tubes 13a to 13e. The other input terminal of each of the fluorescent tubes 13 a to 13 e is grounded by a return board 18 and a return cable 19. The diffuser plate 15 constitutes a light emitting surface of the backlight device 10 and is irradiated with direct light from the fluorescent tubes 13a to 13e or reflected light from the reflection sheet 12. The rear chassis 11 constitutes a casing of the backlight device 10 and accommodates the fluorescent tubes 13a to 13e and the like.

  FIG. 2 is a bottom view of the backlight device 10 of FIG. 3 is a cross-sectional view taken along the line II-II ′ of FIG. As shown in FIGS. 1 to 3, the rear chassis 11 of the backlight device 10 according to the first embodiment is arranged along the direction orthogonal to the longitudinal direction of the fluorescent tubes 13 a to 13 e and the fluorescent tubes 13 a to 13 a. Openings 20a to 20e for installing the luminance measurement sensors are provided directly below 13e.

  When attaching the backlight device 10 to an information device or the like, an information device manufacturer or the like attaches a luminance measurement sensor to each of the openings 20a to 20e. Each luminance measurement sensor always measures luminance while the attached information device is in use.

  The backlight device 10 includes a luminance measurement unit (control unit) that detects an abnormality of the fluorescent tube based on the luminance measured by the luminance measurement sensor. FIG. 4 is a block diagram of the luminance measuring unit 21 of the backlight device 10. As illustrated in FIG. 4, the luminance measurement unit 21 of the backlight device 10 includes luminance measurement sensors 22 a to 22 e, an abnormality detection unit 23, and an abnormality notification unit 24. The luminance measurement sensors 22a to 22e are attached to the openings 20a to 20e of the rear chassis 11, respectively, and constantly measure the luminance of the fluorescent tubes 13a to 13e and notify the abnormality detection unit 23 of the measured values. The abnormality detection unit 23 monitors the abnormality of each received measurement value. For example, the received measurement value is compared with a predetermined value, and if there is a measurement value lower than the predetermined value, it is determined that an abnormality has occurred in the fluorescent tube. When an abnormality occurs, the abnormality detection unit 23 notifies the abnormality notification unit 24 to that effect. The abnormality notification unit 24 notifies the user that an abnormality has occurred in the fluorescent tube. For example, the fact that an abnormality has occurred in the fluorescent tube may be displayed on the liquid crystal panel attached to the backlight device 10, or the occurrence of the abnormality may be notified from an information device or the like to which the backlight device 10 is attached.

  FIG. 5 is a cross-sectional view of a liquid crystal display device using the backlight device 10 shown in FIG. As shown in FIG. 5, a liquid crystal display device is configured by installing a liquid crystal panel 16 on the upper surface of the diffusion plate 15 of the backlight device 10.

  As described above, according to the first embodiment, the rear chassis 11 of the backlight device 10 is arranged in the vicinity of the fluorescent tubes 13a to 13e along the direction orthogonal to the longitudinal direction of the fluorescent tubes 13a to 13e. In addition, openings 20a to 20e for installing the luminance measuring sensors are provided, and the luminance measuring unit 21 constantly monitors the measured values from the respective luminance measuring sensors, so that the luminance of the backlight device 10 is made uniform. By measuring, it is possible to reliably detect the abnormality of each fluorescent tube, and to obtain an effect that it is possible to determine the replacement time of the fluorescent tube or the backlight device before a serious failure occurs.

The opening provided in the rear chassis 11 is not limited to being provided along the direction orthogonal to the longitudinal direction of each fluorescent tube, but may be a position where each installed luminance measurement sensor can measure the luminance of each fluorescent tube. That's fine. Further, the opening may be provided at a position where the luminance measuring sensor can measure the luminance even if it is not directly under each fluorescent tube.
Embodiment 2. FIG.
FIG. 6 is a bottom view of the backlight device 30 according to the second embodiment of the present invention. In FIG. 6, elements common to those in FIG. As shown in FIG. 6, in the backlight device 30 according to the second embodiment, openings 31a to 31e are provided in the vicinity of the same end side of the fluorescent tubes 13a to 13e. As in the first embodiment, when an information equipment manufacturer or the like attaches the backlight device 30 to an information equipment or the like, the brightness measurement sensor is attached to the openings 31a to 31e. The abnormality detection unit 23 of the luminance measurement unit 21 captures the luminance value measured by the luminance measurement sensor, and constantly monitors to detect abnormality of the fluorescent tube. When an abnormality is detected, the abnormality notification unit 24 notifies the user of the occurrence of the abnormality.

A decrease in the brightness of a fluorescent tube generally occurs first at the end of the tube. Therefore, according to the second embodiment, since it is possible to measure the luminance of the tube end portion where the luminance reduction of the fluorescent tube first occurs, the effect that the abnormality of the fluorescent tube can be detected quickly can be obtained.
Embodiment 3 FIG.
FIG. 7 is a bottom view of the backlight device 40 according to the third embodiment of the present invention. In FIG. 7, elements common to those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 7, in the backlight device 40 according to the third embodiment, the openings 41a to 41e are in the vicinity of one end side of the fluorescent tubes 13a to 13e and on the side where the adjacent fluorescent tubes alternate. It is provided in the vicinity.

  In each fluorescent tube, a decrease in luminance occurs from either one end. Therefore, if the luminance can be measured at a position closer to all the tube ends, a decrease in the luminance of each fluorescent tube can be detected more accurately. Therefore, according to the third embodiment, the openings 41a to 41e are provided in the vicinity of the end portions on the side where the adjacent fluorescent tubes are alternated, and therefore, on the same end side of each fluorescent tube as in the second embodiment. As compared with the case where the opening is provided, it is possible to more accurately detect the decrease in luminance, that is, the occurrence of abnormality in the fluorescent tube.

  In addition, each opening part is not limited to being provided in the vicinity of an end portion that is alternated between adjacent fluorescent tubes as shown in FIG. 7, and may be provided in the vicinity of one end side. Further, it may be provided in the vicinity of the tube ends of all the fluorescent tubes. Furthermore, it is not necessary to provide an opening in the vicinity of all the fluorescent tubes, and an opening may be provided in the vicinity of at least two or more fluorescent tubes.

1 is an exploded perspective view of a backlight device according to Embodiment 1 of the present invention. FIG. 2 is a bottom view of the backlight device of FIG. 1. FIG. 3 is a cross-sectional view taken along the line II-II ′ of FIG. 2. It is a block diagram of the brightness | luminance measurement part of the backlight apparatus of FIG. It is sectional drawing of the liquid crystal display device using the backlight apparatus of FIG. It is a bottom view of the backlight apparatus by Embodiment 2 of this invention. It is a bottom view of the backlight apparatus by Embodiment 3 of this invention. It is a bottom view of a conventional direct-type backlight device. It is sectional drawing in I-I 'of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30, 40 Backlight apparatus 11 Rear chassis 12 Reflection sheet 13a-13e Fluorescent tube 14 Lamp support stand 15 Diffuser plate 16 Liquid crystal panel 17 Inverter 18 Return board 19 Return cable 20a-20e, 31a-31e, 41a-41e Opening part 21 Luminance Measurement Units 22a to 22e Luminance Measurement Sensor 23 Abnormality Detection Unit 24 Abnormality Notification Unit

Claims (18)

In a backlight device including a plurality of light sources and a housing member that houses the light sources,
The backlight device according to claim 1, wherein the housing member includes openings in the vicinity of at least two of the plurality of light sources. The backlight device according to claim 1, wherein the opening is provided in the vicinity of each of the light sources. The backlight device according to claim 1, wherein each of the light sources includes a fluorescent tube. The backlight device according to claim 2, wherein the opening is provided directly under each of the light sources. The backlight device according to claim 3, wherein the opening is provided along a direction orthogonal to a longitudinal direction of each light source. The backlight device according to claim 3, wherein the opening is provided in the vicinity of one end side of each of the light sources. The backlight device according to claim 3, wherein the opening is provided in the vicinity of the same end of each of the light sources. 4. The backlight device according to claim 3, wherein the opening is provided in the vicinity of an end portion on the side where the adjacent light sources alternate. LCD panel,
A liquid crystal display device comprising: a plurality of light sources; and a housing member that houses the light sources, wherein the housing member includes a backlight device including openings in the vicinity of at least two of the plurality of light sources. The backlight device according to claim 9, wherein the opening is provided in the vicinity of each of the light sources. The liquid crystal display device according to claim 9, wherein a luminance measurement sensor for measuring the luminance of each light source is attached to the opening. The liquid crystal display device according to claim 9, wherein the opening is provided directly under each of the light sources. The liquid crystal display device according to claim 9, wherein each of the light sources includes a fluorescent tube. 12. The liquid crystal display device according to claim 11, further comprising control means for detecting an abnormality of the light source based on a measurement value from each of the luminance measurement sensors. The liquid crystal display device according to claim 13, wherein the opening is provided along a direction orthogonal to a longitudinal direction of each light source. The liquid crystal display device according to claim 13, wherein the opening is provided in the vicinity of one end side of each of the light sources. The liquid crystal display device according to claim 16, wherein the opening is provided in the vicinity of the same end of each of the light sources. The liquid crystal display device according to claim 16, wherein the opening is provided in the vicinity of an end portion on the side where the adjacent light sources alternate.

Images