WO2008038670A1

WO2008038670A1 - Flashing fluorescent lamp, backlight device, and liquid crystal display device

Info

Publication number: WO2008038670A1
Application number: PCT/JP2007/068695
Authority: WO
Inventors: Tatsuya Ikeda; Naoki Tsutsui; Tomohiro Mizoguchi; Masahiko Tamai
Original assignee: Harison Toshiba Lighting Corporation
Priority date: 2006-09-27
Filing date: 2007-09-26
Publication date: 2008-04-03
Also published as: TW200822171A; KR20090055023A; JPWO2008038670A1

Abstract

Provided is a fluorescent lamp (2) including a fluorescent material layer (23) formed on the inner face of a glass container (21). The fluorescent material layer contains only the fluorescent material (as specified by a fluorescent material containing an activator selected from the group consisting of Sn2+, Pr3+, Eu2+, Eu3+, Ce3+ and Tb3+), which has a 90 % illumination rising time period of 5 milliseconds or less and a one-tenth residual time period of 5 milliseconds or less. This fluorescent lamp can flash quickly so that it can suppress the formation of a residual image if it is used as a backlight of the liquid crystal display device of the flashing type, in which the backlight is flashed in response to the drive of the liquid crystal.

Description

Specification

Fluorescent lamp for flashing, backlight device, and liquid crystal display device

Technical field

The present invention relates to a fluorescent lamp, a backlight device, and a liquid crystal display device used for blinking lighting.

Background art

[0002] Conventionally, as a lighting method of a backlight device used in a liquid crystal television or the like, a method of always lighting a lamp (hereinafter referred to as a conventional method) has been mainstream. The development of a method that illuminates (hereinafter referred to as a blinking illumination method) is underway.

[0003] The blinking lighting method includes a blinking lighting method that lights up in accordance with the on / off timing of a plurality of arranged lamps, a scanning lighting method that lights up while sequentially scrolling by shifting the lamp on / off timing, etc. Is generally known. In any of the methods, there is an advantage that motion blur caused when displaying a moving image can be prevented by combining with driving of a liquid crystal.

[0004] That is, these blinking lighting systems are attracting attention as a means for solving the problems of liquid crystal televisions that are generally said to be weak against moving images. Such a blinking backlight device is disclosed in International Publication No. 04/053826 pamphlet, Japanese Patent Application Laid-Open No. 2004-87489, Japanese Patent Application Laid-Open No. 20 '03 -84739, Japanese Patent Application Laid-Open No. 2002-6815, and the like. ing.

[0005] In a backlight device using such a flashing lighting method, the motion blur that occurs when displaying a moving image can be prevented to some extent, but it cannot be sufficiently prevented, and an afterimage still remains. Remains a big problem.

[0006] As a result of the inventors' investigation of this problem, it has been found that there is a cause in the response speed of the phosphor used in the fluorescent lamp constituting the backlight device. In other words, when the fluorescent lamp used in the conventional method is used in the blinking lighting method, the phosphor reacts with a delay with respect to the on / off input to the fluorescent lamp, so the above problem has occurred. Reached.

Disclosure of the invention

Corrected ^ paper (Rule 91) [0007] As a result of repeated research on the phosphor of the fluorescent lamp suitable for this blinking lighting method, it was possible to realize a blinking lighting fluorescent lamp, a backlight device, and a liquid crystal display device in which an afterimage is less likely to remain than before. The present invention has been proposed.

[0008] An object of the present invention is to provide a fluorescent lamp for blinking lighting, a backlight device, and a liquid crystal display device in which an afterimage hardly remains.

[0009] In order to achieve the above object, the flashing lighting fluorescent lamp of the present invention has a multi-wavelength phosphor composed of a plurality of types of phosphors having a 1/10 afterglow time of 5 msec or less on the inner surface of a glass container. It is formed!

[0010] Further, in the blinking lighting fluorescent lamp of the present invention, the phosphor has a 90% emission rising force S and a time force S5 msec or less.

[0011] Further, in the blinking lighting fluorescent lamp of the present invention, the phosphor includes an activator selected from Sn2 +, Pr3 +, Εu2 +, Eu3 +, Ce3 +, and Tb3 +. is there.

Furthermore, in the blinking lighting fluorescent lamp of the present invention, the phosphor is a multi-wavelength phosphor including red, green, and blue phosphors, and the red phosphor is Sn2 +, Pr3 +, EU2 +, EU3 +, green Phosphors include Eu2 +, Ce3 +, Tb3 +, and blue phosphors include an activator selected from Eu2 +! /.

[0013] In addition, the backlight device of the present invention includes a housing, the fluorescent lamp housed in the housing, and a lighting circuit capable of blinking and lighting the fluorescent lamp. It is.

[0014] Further, a liquid crystal display device of the present invention includes the above-described backlight device and a liquid crystal panel disposed on the light emitting surface side of the backlight device.

[0015] According to the present invention, it is possible to realize a blinking lighting fluorescent lamp, a backlight device, and a liquid crystal display device in which an afterimage hardly remains.

Brief Description of Drawings

FIG. 1 is a diagram for explaining a backlight device according to a first embodiment (embodiment) of the present invention.

2 is a diagram for explaining a cross section of the fluorescent lamp shown in FIG. FIG. 3 is a diagram for explaining the light emission characteristics of a fluorescent lamp coated with a Y203: Eu3 + phosphor.

[Fig. 4] A diagram for explaining the presence or absence of afterimages when moving images on a liquid crystal are projected by fluorescent lamps with different response speeds.

[Fig. 5] Example (a diagram for explaining the light emission characteristics when the lamp of Example ^ blinks by blinking lighting).

FIG. 6 is a diagram for explaining the light emission characteristics when the lamp of Comparative Example l is blinking and blinking.

FIG. 7 is a diagram for explaining a difference between Example 1 and Comparative Example 1.

[Fig. 8] A diagram for explaining the response speed of a fluorescent lamp when various phosphors are used.

FIG. 9 is a diagram for explaining the response speed of a fluorescent lamp when the phosphors of FIG. 8 are combined.

FIG. 10 is a diagram for explaining a backlight device according to a second embodiment of the present invention.

FIG. 11 is a diagram for explaining a liquid crystal display device according to a third embodiment of the present invention.

FIG. 12 is a diagram for explaining light emission obtained by the liquid crystal display device of the present invention.

Detailed Description of the Invention

Hereinafter, a backlight device using a blinking lighting fluorescent lamp according to an embodiment of the present invention will be described with reference to the drawings.

[0018] (First embodiment)

FIG. 1 is a diagram for explaining a backlight device according to a first embodiment of the present invention.

[0019] The backlight device BL of the present embodiment is a direct type. The casing of the knocklight BL is composed of a front frame la and a back frame lb. An opening surface is formed in the front frame 1a. The back frame lb has a bottomed opening shape, and a highly reflective reflecting surface is formed on the inner side.

[0020] A plurality of elongated fluorescent lamps 2 are arranged inside the knock frame lb so that their tube axes are substantially parallel to each other. In this embodiment, the cold cathode fluorescent lamp However, a hot cathode fluorescent lamp, an external electrode fluorescent lamp, a flat fluorescent lamp or the like may be used, and there is no limitation on the type, shape, size, and the like.

A specific structure of the fluorescent lamp 2 is shown in FIG.

The main part of the fluorescent lamp 2 is composed of a glass container 21 made of, for example, soft glass, and a mixed gas composed of Ne and Ar and mercury are enclosed therein. Electrode mounts 22 a and 22 b are sealed at both ends of the glass container 21. The electrode mounts 22a and 22b are composed of electrodes 22al and 22bl and bead glasses 22a2 and 22b2.

A phosphor 23 is formed on the inner surface of the glass container 21. In the present invention, it is desirable to use a phosphor having a high response speed. FIG. 3 is a diagram for explaining the light emission characteristics of a fluorescent lamp coated with a Y203: Eu3 + phosphor. In the figure, the horizontal axis represents time, and the vertical axis represents voltage or current value. Waveform (A) in the figure is an on / off signal that is a voltage waveform for on / off control of the fluorescent lamp, waveform (B) is the lamp voltage waveform, waveform (C) is the lamp current waveform, waveform is the lamp emission intensity. It is an output voltage waveform obtained by photoelectric conversion with a photodiode. These waveforms are measured with an oscilloscope.

[0024] As can be seen from the figure, the fluorescent lamp 2 responds to the on / off signal waveform (A) with the lamp voltage and lamp current waveforms (B) and (C) without delay, but the lamp emission waveform (D). The reaction tends to be delayed. This is a result of the response speed of the phosphor. Therefore, it is most desirable to use a phosphor whose response speed is the same as that of the on / off signal (A), but such a phosphor is difficult to realize.

[0025] Therefore, the inventor investigated the response speed of various phosphors, and 1/10 afterglow time (when the maximum brightness is A, the time from the brightness power of the lamp to 0.1A) A three-wavelength fluorescent lamp with a lmsec to 10 msc was made. Then, a moving image on the liquid crystal was projected with the fluorescent lamp, and a test was conducted on 10 subjects to see if there was an afterimage in the moving image.

The results are shown in FIG. As can be seen from Fig. 4, it was found that if the 1/10 afterglow time was 5 msec or less, it was hardly visible to the human eye as an afterimage, and if it was 3 msec or less, it could hardly be recognized as an afterimage. Incidentally, the Y203: Eu3 + phosphor shown in Fig. 3 has a 90% rise time and 1/10 afterglow time of about 2.5 msec. It is suitable as the phosphor of the present invention, which is fast. In most phosphors, it was found that the rise of light emission and the fall of light emission are correlated. For example, the phosphor in Fig. 3 has a 1/10 afterglow time power of ¾.5 msec, while the 90% light emission rise time (the time until the lamp brightness reaches 0 to 0.9 A) is also about 3 msec. In other words, 1/10 afterglow time and 90% emission rise time are almost the same result, so a phosphor with a fast emission fall has a fast emission rise! / / Yeah.

In FIG. 1, a diffusion plate 3 is arranged on the opening side of the back frame lb. Diffusion plate

As for 3, it is desirable to use one having a transmittance of 50% to 85% so that unevenness in light emission can be reduced and efficiency is not lowered excessively.

[0028] On the diffusing plate 3, an optical sheet 4 is disposed! As the optical sheet 4, one sheet or a plurality of sheets such as a diffusion sheet and a prism sheet can be used according to the purpose.

[0029] A lighting circuit 5 is arranged on the back side of the knock frame lb. The lighting circuit 5 is typically a PWM (Pulse Width Modulation) circuit as long as the fluorescent lamp 2 can be turned on and off. In the case of this PWM circuit, it is desirable to turn on the lamp with a frequency of 50 to 300 Hz and a duty ratio of 10 to 70%. In this case, as a matter of course, it is desirable to set the frequency and the duty ratio so that the lamp off period becomes longer than the 1/10 afterglow time from the viewpoint of afterimage suppression.

[0030] One specification of an example of the backlight device of the present invention and a comparative example is shown below.

[Example 1]

Backlight device BL; size = 32 inches (about 760mm X about 440mm),

Fluorescent lamp 2; cold cathode fluorescent lamp, inner diameter = 2.0 mm, outer diameter = 3.0 mm, lamp current = 6.0 mA, number of lamps used = 16, lamp pitch = 23.8 mm, distance between fluorescent lamp 2 and diffuser 3 = 14 mm , Phosphor 23; Y203: Eu3 + (R), Y2Si5: Tb3 + (G), BaMg2A110O17: Eu2 + (B),

Diffuser 3; transmittance = 60%,

Optical sheet ₄ ; diffusion sheet, prism sheet,

Lighting circuit 5: PWM circuit, frequency = 50Hz, duty ratio = 50%.

[0032] (Comparative Example 1)

Phosphor 23; Y203: Eu3 + (R), LaP04: Ce3 +, Tb3 + (G), BaMg2A110O17: Eu2 + (B), The configuration other than the phosphor 23 has the same specifications as in Example 1.

FIG. 5 is a diagram for explaining the light emission characteristics when the lamp of Example 1 and FIG. 6 are turned on by blinking lighting of the lamp of Comparative Example 1. In these figures, the horizontal axis represents time, and the vertical axis represents voltage or current value. Waveform (A) in the figure is an on / off signal that is a voltage waveform for controlling on / off of the fluorescent lamp, waveform (B) is the lamp voltage waveform, waveform (C) is the lamp current waveform, and waveform (D) is the lamp waveform. It is an output voltage waveform obtained by photoelectrically converting the emission intensity with a photodiode.

[0034] Comparing the light emission waveforms of FIGS. 5 and 6, it can be seen that in Example 1, the response speed of the comparative example beam is faster. Specifically, the 1/10 afterglow time of Example 1 is about 3 mse _C , and Comparative Example 1 is about 7 msec. Example 1 is turned off earlier. Also, regarding the 90% light emission rise time, Example 1 is less than 3 msec, while Comparative Example 1 is less than 8 msec.

[0035] It should be noted that when each lamp is mounted on a liquid crystal display device and a moving image is taken, the force that Example 1 hardly left as an afterimage is comparatively clear in Example 1 that an afterimage remains and the moving image appears blurred. there were. In addition, in order to further eliminate the afterimage, the brightness was compared when the liquid crystal was closed at the lamp turn-off timing, that is, when the lamp brightness was obtained only during the lamp on-time. As a result, when the duty ratio was 100%, the luminance of both lamps relative to the luminous flux was about 95% in Example 1 and about 70% in Comparative Example 1. That is, the liquid crystal display device using Example 1 was clearly felt brighter.

[0036] The reason for such a result is presumed as follows.

The difference between Example 1 and Comparative Example 1 is only that a green phosphor having a different response speed with respect to the on / off signal is used as shown in FIG. However, as can be seen from FIGS. 5 and 6, when a three-wavelength phosphor is used, there is a large difference in the rise and afterglow of the lamp. From this, when flashing with the fluorescent lamp 2 coated with a three-wavelength phosphor, if one of the phosphors of R (red), G (green), and B (blue) has a slow response speed, It was speculated that the response speed of fluorescent lamps would slow down.

[0038] Therefore, when a three-wavelength phosphor combining various phosphors was formed on a lamp and tested, all of them were the slowest in response speed, and the phosphor was a three-wavelength phosphor. It was confirmed that the response speed was determined. Therefore, with a three-wavelength fluorescent lamp for blinking lighting, For all RGB! /, The response speed is fast! / And it is necessary to use a combination of phosphors. Even in the case of a four-wavelength phosphor mixed with phosphors such as red, green, blue, and crimson, or a multi-wavelength phosphor mixed with more phosphors, only when the response speed of all the phosphors is high. The response speed of light emission is fast! / A fluorescent lamp can be realized.

[0039] Here, further research by the inventors discovered that the response speed of the phosphor is mainly related to the activator of the phosphor. In other words, the composition of the phosphor is expressed as Y203: Eu3 +, the force S that generally calls Y203 as the matrix and Eu3 + as the activator S, as can be seen from FIG. It was found that it was almost dependent on the drug. Therefore, when a test was conducted by paying attention to the phosphor activator, a phosphor composed of an activator selected from Sn2 +, Pr3 +, EU2 +, EU3 +, Ce3 +, Tb3 + would be 1/10 of 5 msec or less. It turned out that it was easy to realize the afterglow time. However, since Eu3 + and Tb3 + activators have a response speed of several msec, there are phosphors whose 1/10 afterglow time exceeds 5 msec depending on the combination with the base material. Therefore, in these cases, only phosphors with 1/10 afterglow time of 5 msec or less are suitable for blinking lighting. On the other hand, Sn2 +, Pr3 +, EU2 +, and Ce3 + activators have 90% emission rise time and 1/10 afterglow time of about 0.1 msec, and the phosphor responds almost without delay to the on / off signal. In particular, it can be said that it is suitable for flashing lighting applications. Incidentally, when a plurality of activators are used, the characteristics of the activator having the slowest response speed tend to be obtained as the response speed of the phosphor. For example, in the case of LaP04: Ce3 +, Tb3 +, which is the green phosphor of Comparative Example 1, the response speed of Ceb + containing Ce3 + with a high response speed is obtained, and the response speed of Tb3 + with a slower response speed is obtained. That is, in the case of a plurality of activations, if one of them includes an activation agent having a slow response speed, it is not suitable as a phosphor used for blinking lighting.

[0040] In addition, since the characteristics of the phosphor vary depending on the type and valence of the activator, there are an activator that can be used for each desired emission color and an activator that cannot be used. Sn2 +, Pr3 +, Εu2 +, Eu3 +, Ce3 +, Tb3 + activators, Sn2 +, Pr3 +, Eu2 +, Eu3 + are red phosphors, Eu2 +, Ce3 + are green phosphors, Tb3 +, Eu2 + are blue phosphors Can be used.

[0041] Next, as shown in Fig. 9, three-wavelength fluorescent lamps using various RGB phosphors were created and the response speed was tested. As a result, the 90% emission rise time is about 3 ms in Examples 2, 3, and 5. ec, Example 4 was lmsec or less, and Comparative Examples 2 and 3 were 10 msec or more. The 1/10 afterglow time was about 3 msec in Examples 2, 3, and 5, lmsec or less in Example 4, about 6 msec in Comparative Example 2, and 10 msec or more in Comparative Example 3. From the above, it was confirmed that any combination of phosphors with a fast response speed can be applied to a flashing lighting type backlight device with a fast response speed.

[0042] The fluorescent lamp of the present invention is also effective when dimming by the PWM method.

In other words, dimming is performed mainly for the purpose of adjusting the contrast, but as a result, it is difficult to leave afterimages!

Therefore, in the first embodiment, blinking lighting is performed using a fluorescent lamp in which an RGB phosphor 23 having a 1/10 afterglow time force of ^ msec or less is applied to the inner surface of the glass container 21. Thus, it is possible to provide a backlight device in which an afterimage hardly remains. Also, in most cases, such phosphors have a 90% emission rise time of 5 msec or less. Therefore, when the liquid crystal display device is configured by synchronizing the lamp and liquid crystal on / off, the luminance loss of the lamp is small. High brightness can be realized.

[0044] Specifically, the red phosphor is Sn2 +, Pr3 +, Eu2 +, Eu3 +, the green phosphor is Eu2 +, Ce3 +, Tb3 +, the blue phosphor is a lamp with a three-wavelength phosphor containing an activator selected from Eu2 +. If configured, the above effect can be reproduced.

In the above embodiment, the blinking lighting method is used as the backlight device lighting method, but the present invention can also be effectively applied to a scanning lighting type backlight device.

FIG. 10 is a diagram for explaining a scanning lighting type backlight device. In this backlight unit, each of the 12 lamps is divided into 2 lamps to form 6 lamp groups, and each lamp group is input with an on / off signal that is shifted by 1/6 time, and the scanning lights up. Is doing. The on / off signal has a frequency of 60 Hz and a duty ratio of 50%, and is generated by the PWM method. This scanning lighting method is different from the blinking lighting method in that one or more of the lamp groups are always turned on in the lighting state. A light device can be realized. [0047] (Second Embodiment)

FIG. 11 is a diagram for explaining an embodiment of a liquid crystal display device using the fluorescent lamp of the present invention.

[0048] In the liquid crystal display device, a housing is constituted by a front case FC and a back case BC. A liquid crystal panel LCP is disposed on the opening surface of the front case FC. The back case BC has a shape of a bottomed opening, and a backlight device BL is disposed therein.

[0049] In the case of a liquid crystal display device, it is possible to combine the blinking lighting of the backlight device BL and the operation of opening and closing the liquid crystal panel LCP. FIG. 12 is a diagram for explaining the light emission characteristics when the lamp of the backlight device BL is turned on and off. In the figure, the horizontal axis represents time, and the vertical axis represents voltage or current value. In addition, waveform (A) in the figure is an on / off signal that is a voltage waveform for controlling on / off of the fluorescent lamp, waveform (B) is the lamp voltage waveform, waveform (C) is the lamp current waveform, and waveform (D) is the lamp waveform. It is an output voltage waveform obtained by photoelectrically converting the emission intensity with a photodiode. Furthermore, the waveform) is a signal for opening and closing the liquid crystal forming the liquid crystal panel LCP, the waveform) is the emission waveform obtained by the liquid crystal panel LCP, and the waveform (G) is the emission waveform that cannot be obtained by the liquid crystal panel LCP. is there.

[0050] As shown in FIG. 12, since the afterglow of the lamp can be cut by closing the liquid crystal panel LCP at the same time when the OFF signal is input to the backlight device BL, the motion blur is caused by the combination of both. Can be almost completely prevented. However, since the cut light cannot be used as liquid crystal light, the brightness is reduced accordingly. For example, in Comparative Example 1, the luminance is reduced by about 30%. In that respect, in the backlight device using the fluorescent lamp of the present invention, since the response speed of the lamp is fast, the light to be cut is reduced, and high luminance can be achieved.

Therefore, in the second embodiment, it is possible to realize a liquid crystal display device with high luminance and little afterglow even when flashing.

Claims

The scope of the claims

[1] A glass container in which a discharge medium is enclosed, a discharge electrode provided at an end of the glass container, and multi-wavelength fluorescence composed of a plurality of types of phosphors formed on the inner surface of the glass container, These phosphors have a 1/10 afterglow time of 5 msec or less.

[2] The phosphor is characterized in that a 90% emission rise time force is 5 msec or less.

1. A fluorescent lamp for blinking lighting according to 1.

[3] The flashing fluorescent lamp according to claim 1, wherein the phosphor includes an activator selected from Sn2 +, Pr3 +, EU2 +, EU3 +, Ce3 +, and Tb3 +.

[4] The fluorescent lamp for flashing lighting according to claim 2, wherein the phosphor includes an activator selected from Sn2 +, Pr3 +, EU2 +, EU3 +, Ce3 +, and Tb3 +.

[5] The phosphor is a multi-wavelength phosphor including red, green, and blue phosphors. The red phosphor is Sn2 +, Pr3 +, EU2 +, EU3 +, the green phosphor is EU2 +, Ce3 +, Tb3 +, and the blue phosphor is The fluorescent lamp for flashing lighting according to claim 1, characterized in that it contains a selected activator.

[6] The phosphor is a multi-wavelength phosphor including red, green, and blue phosphors. The red phosphor is Sn2 +, Pr3 +, EU2 +, EU3 +, the green phosphor is EU2 +, Ce3 +, Tb3 +, and the blue phosphor is The fluorescent lamp for flashing lighting according to claim 2, comprising a selected activator.

[7] The phosphor is a multi-wavelength phosphor including red, green, and blue phosphors. The red phosphor is selected from Sn2 +, Pr3 +, EU2 +, the green phosphor is selected from EU2 +, Ce3 +, and the blue phosphor is selected from Eu2 +. The fluorescent lamp for blinking lighting according to claim 1, further comprising an activator.

[8] The phosphor is a multi-wavelength phosphor including red, green, and blue phosphors. The red phosphor is selected from Sn2 +, Pr3 +, EU2 +, the green phosphor is selected from EU2 +, Ce3 +, and the blue phosphor is selected from Eu2 +. The fluorescent lamp for blinking lighting according to claim 2, further comprising an activator.

[9] A backlight device comprising: a casing; the fluorescent lamp according to claim 5 housed in the casing; and a lighting circuit capable of blinking and lighting the fluorescent lamp.

[10] The casing, the fluorescent lamp according to claim 6 accommodated in the casing, and the fluorescent lamp And a lighting circuit capable of blinking lighting.

[11] The backlight device according to claim 9,

And a liquid crystal panel disposed on the light emitting surface side of the backlight device.

[12] The backlight device according to claim 10,