JP2006059590A - Ccfl illumination device, and backlight device using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CCFL illumination device and a backlight device using this, wherein it is arranged that uniformity of brightness can be retained regardless of non-uniformity of parts or the like, structure of various constituting members, or assembly tolerance. <P>SOLUTION: This is the CCFL illumination device and the backlight device using this wherein they are actuated by a leakage type transformer without using a ballast capacitor, and wherein the center part of the tubular CCFL main body to which a high voltage is applied between electrodes to emit light is made to have GND or a nearly low pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel CCFL (Cold Cathode Fluorescent Lamp) illumination device and a backlight device using the same.

  As a backlight using this type of CCFL, a backlight having the structure shown in FIGS. 4A, 4B, and 4C is known (for example, see Patent Document 1).

  1a is a CCFL, 2a and 2a are lighting devices provided at both ends of the CCFL 1a, and are provided with a voltage and an oscillation function necessary for lighting the CCFL 1. 3 is a bending prevention support provided at a location necessary to prevent the bending of the CCFL 1, 4 is a reflector, 5 is a diffusion sheet provided on the surface, 6 is a member for fixing the CCFL 1, and the CCFL 1 emits light Light is reflected by the reflector 4 and can be irradiated through the diffusion sheet 5. And since the display screen becomes large recently, the length of CCFL1 also becomes long and the tube voltage and the lighting start voltage have become high.

For this reason, the lighting devices 2a and 2a mainly use leakage type transformers that do not use ballast capacitors, as shown in FIGS. 5A and 5B, at both ends of CCFLs 1a and 1a of straight tubes or U-shaped tubes. The lighting device 2 provided is turned on by applying alternating voltages having a phase difference of 180 °.
JP 2004-127538 A

  By the way, in such a conventional backlight, the center of the CCFL can be regarded as a virtual GND if all the conditions such as the component variation structure and the assembly tolerance are the same, and the luminance is uniform. However, in reality, not all conditions are met due to component variations and the backlight structure. In such a case, the center of the CCFL is not in the GND state and has a potential difference, so that the uniformity of luminance is impaired.

  The present invention has been made paying attention to the above points, and uses a CCFL illumination device capable of maintaining luminance uniformity regardless of component variations or the structure and assembly tolerance of various components. An object is to provide a backlight device.

  This invention can solve the said subject by providing the following structures.

  (1) A CCFL lighting device that operates with a leaky transformer that does not use a ballast capacitor, and the central portion of the tubular CCFL body that emits light by applying a high voltage between the electrodes is configured to be close to GND or low pressure. CCFL lighting device characterized.

  (2) A backlight device using the CCFL illumination device of (1) as a light source.

  Since the present invention can maintain brightness uniformity regardless of component variations and various structural members and assembly tolerances, a high-quality CCFL illumination device and a backlight device using the same can be provided.

  An embodiment of the present invention will be described below with reference to the drawings.

  In addition, before describing an Example, the theoretical basis of this invention is demonstrated based on FIG.

  FIG. 1 shows a simple test method of the CCFL potential difference confirmation test in (a) and the results in (b) and (c).

  FIG. 1 is an explanatory diagram of measuring applied voltage by connecting two CCFLs a and a having a length of about 1/2 of a straight pipe CCFL. An alternating voltage having a phase difference of 180 ° was applied to the lighting device 2 for both electrodes. However, in order to generate a voltage difference, the load conditions of the left and right CCFLs a and a were slightly changed.

  In addition, the lighting device 2 used for this test is applied using a leaky transformer that does not use a ballast capacitor.

  As a result, a voltage of about 90 Vrms was confirmed with the left and right CCFLs a, a connected. This graph is shown in FIG.

  Next, when an aluminum foil was wound around a portion close to the end face where the left and right CCFLs a, a were connected, the voltage difference was 30 Vrms, which was improved to a potential difference of about 1/3. The state is shown in FIG.

  Further, when both ends of the left and right CCFLs a and a are connected to GND, the potential difference is naturally 0 Vrms.

  As a result of the above test, it has been found that the luminance is uniform because the center of the CCFL is in the GND state or has a low potential difference close thereto.

  FIG. 2 shows an embodiment in which the CCFL illumination device according to the present invention and the CCFL illumination device are used as a light source of a backlight device, wherein (a) is an explanatory view of a slope of a backlight incorporating the CCFL, and (b) (A) The expanded sectional explanatory drawing of the principal part, (c) is a slope explanatory drawing of CCFL which deform | transformed.

  In the figure, 1 indicates three CCFLs arranged in parallel, 2 and 2 indicate lighting devices provided at both ends of the CCFL 1, and a leakage type transformer not using a ballast capacitor is used in FIGS. 2 (a) and 2 (b). Illumination is performed by applying alternating voltages having a phase difference of 180 ° to the lighting devices 2 and 2 of a straight tube or a U-shaped tube as shown.

  Reference numeral 7 denotes a bar-shaped conductive spacer brought into contact with the central portion P of each CCFL 1 (see FIGS. 2A and 2B). In FIG. 2C, the conductive spacer 7 may be replaced with a conductive band 7a such as an aluminum foil wound around the central portion P of the CCFL 1.

  Then, the conductive spacer 7 and the conductive band 7a are connected to the GND, or the GND is in the vicinity.

  In the figure, the same or equivalent parts as those of the conventional structure of FIG.

  With the above configuration, when the lighting device 2 emits light by applying an AC voltage using a leaky transformer without using a capacitor to each CCLF 1, the central portion P of each CCLF 1 has a conductive spacer 7 or a conductive band. Since the conductive processing is performed at 7a and connected to GND, the potential difference becomes zero or close to zero, and the luminance difference can be reduced.

  Therefore, a high-brightness illumination effect can be achieved as a backlight.

  As a means for conducting the conductive processing at the central portion P of the CCFL 1, it is naturally possible to use a structure in which the CCFL is connected to or close to the GND by sheet metal or the like.

BRIEF DESCRIPTION OF THE DRAWINGS The simple test method for the potential difference confirmation test of CCFL which shows the theoretical basis of this invention is shown, (a) is the explanatory drawing, (b), (c) is a graph which shows two examples of a test result, respectively. 1 shows a CCFL illumination device according to an embodiment of the present invention and a backlight device using the same, wherein (a) is an explanatory diagram of the entire slope, (b) is an enlarged sectional explanatory diagram of the main part, and (c) is an explanatory diagram of the main part. Explanation of slopes of CCFLs with other modified configurations A circuit configuration diagram of the CCFL is shown, in which (a) is a straight pipe, and (b) is a U-shaped pipe. The conventional example of CCFL is shown, (a) is the explanatory view of the slant of the backlight showing the whole structure, (b) is a side view of (a), (c) is a partially enlarged cross-sectional explanation of the main part of (a). Figure In the circuit configuration diagram of FIG. 4, (a) shows a case where a straight pipe is used, and (b) shows a case where a U-shaped pipe is used.

Explanation of symbols

1 CCFL (corresponding to CCFL main unit)
2 Lighting device 1a Conventional CCFL
2a Conventional lighting device 3 Bending prevention support 4 Reflector 5 Diffusion sheet 7 Conductive spacer 7a Conductive band

Claims (2)

  A CCFL lighting device that operates with a leaky transformer that does not use a ballast capacitor, and is characterized in that a central portion of a tubular CCFL body that emits light by applying a high voltage between electrodes is configured to be close to GND or low pressure. CCFL lighting device.   A CCFL illumination device according to claim 1 is used as a light source.

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