JP3278390B2 - Flat fluorescent lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat fluorescent lamp mainly used for a backlight of a liquid crystal display panel or the like.

[0002]

2. Description of the Related Art In recent years, liquid crystal panels have been used in electronic devices such as personal computers and liquid crystal televisions. However, since the liquid crystal panel itself is not a light emitting element, it is common to arrange a backlight behind the liquid crystal panel in order to brightly display an image on the liquid crystal panel. Such electronic devices are required to be thinner, and flat fluorescent lamps are attracting attention as backlights satisfying this requirement. FIG. 8 is a sectional view showing a general structure of a flat fluorescent lamp. The flat fluorescent lamp has a structure in which a glass box (2) having an open top surface is covered with a windshield (1) covering the top opening, and mercury and argon are contained in the box (2). An inert gas such as a gas is sealed. A pair of electrode pieces (4) and (5) are provided in the box (2), and a thin film of the phosphor (7) is formed on the inner bottom surface of the box (2). A conductive film (9) is formed on the upper surface of the windshield (1), and the electrode pieces (4) and (5) are close to the conductive film (9). A negative potential is applied to one electrode piece (4), and the other electrode piece (5) is connected to ground.

When a negative potential is first applied to the negative electrode piece (4) at the start of lighting, Coulomb repulsion between the negative electrode piece (4) and the electrons in the conductive film (9) causes the ground electrode piece (4) to be formed in the conductive film (9). An electron flow toward 5) occurs. Since the electrode pieces (4) and (5) and the conductive film (9) are close to each other, a discharge occurs due to a potential difference between the electrode pieces (4) and (5) and the conductive film (9). Once the discharge is thus induced, a direct discharge occurs between the two electrode pieces (4) and (5), and the discharge then becomes a steady state. Electrons from the electrode piece (4) excite mercury in the box (2), and the phosphor (7) emits light according to the excitation wavelength of the mercury.
Illuminate the area above (1).

In this case, since the pressure of the inert gas in the box (2) is lower than the atmospheric pressure, the windshield plate (1) and the box are set as shown by a dashed line in FIG. The bottom surface of the body (2) may be depressed inward by being pushed by the atmospheric pressure. That is, in the flat fluorescent lamp, the space through which electrons flow is narrower in the central portion than in the peripheral portion, and the discharge resistance is increased. For this reason, phosphor
(7) makes it difficult to emit light, and there is a problem that the luminance of the central part of the flat fluorescent lamp is lower than that of the peripheral part. In particular, in a thin flat fluorescent lamp, even a slight depression increases the discharge resistance, and the luminance at the center tends to decrease.

[0005] In view of this point, the applicant has previously proposed a flat fluorescent lamp shown in FIGS.
179470, unpublished invention). This is a box
Boxes (2) are provided with ridges (8) and (8) on the bottom of (2) in a grid pattern.
Is partitioned into a storage chamber (3) to which a liquid phosphor (7) is applied. Each ridge (8) is provided low at the center of the box (2) and high at the periphery, whereby the film of the phosphor (7) is formed at the center of the bottom of the box (2). Thin and thick at the periphery. That is, the film of the phosphor (7) on the bottom surface of the box (2) is formed to have a concave shape at the center, and when the front glass plate (1) is mounted in the box (2), the film becomes large. Even if the windshield plate 1 is depressed inward due to atmospheric pressure, the upper surface of the phosphor 7 is formed in a shape that allows for the depressed amount. Also, since the ridges (8) and (8) are provided on the bottom surface of the box (2),
The bottom surface of the box (2) is reinforced and hardly bent. Therefore,
The thickness of the discharge space, which is the distance between the bottom surface of the box (2) and the windshield (1), is kept substantially the same at the periphery and the center of the flat fluorescent lamp.

[0006]

The flat fluorescent lamp of this kind is:
It is used by being incorporated into an electronic device such as a digital still camera, and further thinning is required. However, even if the conventional shape shown in FIG. 10 and FIG. 11 is reduced in thickness, the measures against the bending deformation of the box body (2) cannot be said to be sufficient, and the luminance unevenness of the fluorescent lamp remains. As shown in FIG. 11, the flat fluorescent lamp has a flat rectangular shape. However, as the thickness of the flat fluorescent lamp decreases, the bending deformation along the long side of the box (2) becomes particularly large.
In addition, there is also a case where it is bent while being twisted around the long side direction.
On the other hand, such flat fluorescent lamps have a
It is known that the light travels along the inner surface of (2). In particular, in the case of a small-sized fluorescent lamp, the brightness gradually increases from the periphery to the center of the box (2). However, when a fluorescent lamp slightly larger than the small size is incorporated into an electronic device and turned on, a phenomenon occurs in which only the peripheral portion and the central portion of the fluorescent lamp become bright. This is probably because the power supplied from the electronic device is not more than a certain value, and the power supply is not sufficient for the fluorescent lamp.
The function as a fluorescent lamp cannot be fully exhibited. The present invention
It is an object of the present invention to reduce bending deformation and luminance unevenness in a thin fluorescent lamp.

[0007]

The flat fluorescent lamp is provided with a pair of discharge electrode pieces (4) and (5) in a box (2) whose upper surface is covered by a windshield (1). And inside the box (2),
A dried phosphor (7) film is formed. The inside of the bottom surface of the box (2) is a liquid phosphor by a plurality of ridges (8) and (8).
(7) is divided into storage rooms (3) and (3) where each storage room
In (3), the surface of the phosphor (7) adheres to the ridge (8) and rises, and the liquid surface is prevented from lowering under the influence of the surface tension with the ridge (8). Reservoir (3) located around the bottom of (2)
By the reinforcing rib (85) provided between the ridges (8) and (8),
The box (2) is partitioned into smaller sections than the storage chamber (3) at the center. In addition, reinforcing ribs are provided around the bottom of the box (2).
Instead of (85), a stepped surface (6) having a height equal to or greater than each protruding ridge (8) and on which the phosphor (7) is applied may be formed.

[0008]

[Operation and effect] By providing the reinforcing rib (85),
The strength of the peripheral portion of the box (2) can be further increased. Such fluorescent lamps are required to be further reduced in thickness as electronic devices to which the fluorescent lamps are attached are downsized. However, with the reduction in thickness, the amount of depression of the box (2) with respect to the overall thickness of the fluorescent lamps is increased. And the uneven brightness of the fluorescent lamp increases. For this reason, the box
By reinforcing the bottom surface of (2) with the reinforcing rib (85), bending deformation due to atmospheric pressure is reduced, and increase in luminance unevenness is prevented. In the case of a fluorescent lamp in which a step surface (6) higher than the ridge (8) is formed in the periphery of the box (2), the fluorescent material on the step surface (6)
The gap between (7) and the windshield (1) is reduced. Thereby, the peripheral part of the box (2) becomes darker than the central part, for example, because the discharge resistance becomes large in the peripheral part of the box (2), and can be suitable for an actual use state. Also, stepped surface
The formation of (6) naturally has the effect of reinforcing the box (2).

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An example of the present invention will be described below in detail with reference to the drawings. The same components as those of the related art are denoted by the same reference numerals, and detailed description thereof is omitted. The external configuration of the fluorescent lamp is the same as the conventional one. That is, as shown in FIG. 1, an inert gas such as mercury and argon gas is sealed in a glass box (2) whose upper surface is covered by a windshield plate (1), and a pair of inert gases is provided. Electrode pieces (4) (5)
Are arranged parallel to each other. The electrode pieces (4) and (5) are sandwiched between frit glasses (20) and (20). A conductive film (9) is formed on the upper surface of the windshield (1). The conductive film (9) may be formed on the back surface of the box (2). ) May be removed and a shield plate (not shown) covering the flat fluorescent lamp may be used instead. The discharging operation is the same as the conventional one, and a detailed description is omitted.

FIG. 2 is a cross-sectional view of the flat fluorescent lamp according to this embodiment taken along a vertical plane including the line BB of FIG. 1 and viewed in the direction of the arrow. FIG. 3 is a bottom view of the inside of the box (2). FIG. A plurality of elongated ridges (8) and (8) are arranged in a lattice on the bottom surface of the box (2), and the bottom surface of the box (2) is partitioned into a storage chamber (3) by the ridges (8). Can be Between adjacent ridges (8) and (8) constituting the storage chamber (3), a phosphor having a thickness of several μm to several tens μm is provided.
The film of (7) is formed. The phosphor (7) is a well-known substance that emits light in response to ultraviolet light having an excitation wavelength of mercury. The phosphor (7) is a viscous liquid at the beginning of coating, but is dried to form a film.

In the coated state, the phosphor (7) is affected by the surface tension acting between the ridges (8) and (8), so that the liquid positioned between the adjacent ridges (8) and (8) is not affected. The amount of surface drop is small. Therefore, if the interval between the ridges (8) and (8) is reduced, the ridges (8)
(8) Variation in film thickness can be reduced. In addition, box (2)
Has a width of about 63.5 mm, a depth of about 48.5 mm, and a height of about 3.3 mm, and corresponds to a fluorescent lamp of about 2.5 inches. The height of the ridge (8) is formed to be about 0.15 mm to 0.2 mm. In addition, the storage chamber (3) is formed to have a lateral dimension and a depth dimension of about 5 mm as shown in FIG. 3, but it goes without saying that the size of the flat fluorescent lamp is not limited to this. In the flat fluorescent lamp of the above-mentioned size, six ridges (8) are provided horizontally and nine vertically, but in FIG. Is indicated by subtracting.

The box (2) has a rectangular bottom surface. Reinforcing ribs (85) are provided in the horizontal rows of the storage chambers (3) (3) located closest to the longest side. The pitch between the reinforcing ribs (85) is about 2.5 mm, and the reinforcing ribs (85) extend vertically toward the long side of the box (2). Due to the reinforcing ribs (85), each row of the collecting chambers (3) (3) located closest to the longest side is a box body.
It is divided into smaller sections than the storage chamber (3) located at the center of (2). By providing the reinforcing rib (85), the box body
The strength of the peripheral portion of (2) can be further increased. Such fluorescent lamps are required to be further reduced in thickness as electronic devices to which the fluorescent lamps are attached are downsized. However, with the reduction in thickness, the amount of depression of the box (2) with respect to the overall thickness of the fluorescent lamps is increased. And the uneven brightness of the fluorescent lamp increases. For this reason, box (2)
Is reinforced by a reinforcing rib (85) to reduce bending deformation due to atmospheric pressure and prevent an increase in luminance unevenness.

In this case, the amount of bending deformation along the long side of the box (2) is naturally larger than the amount of bending deformation along the short side.
Therefore, the horizontal row of storage chambers (3) located closest to the longest side
Reinforcing ribs (85) are provided in (3) to reduce the bending deformation along the long side of the box (2) and the torsional deformation around the long side direction. When the fluorescent lamp is turned on, the electron flow is a box (2).
As described later, in a fluorescent lamp slightly larger than a small lamp, the central portion and the peripheral portion of the box (2) tend to be brighter. In actual use of fluorescent lamps, the center of the box (2) may be brightest and the periphery may be slightly darker. Therefore, a reinforcing rib (85) is provided around the periphery of the box (2) to bend. By reducing the deformation, the uneven brightness at the periphery of the box (2) was reduced. In the above example, the reinforcing ribs (85) are provided in the horizontal rows of the storage chambers (3) (3) located closest to the longest side. Reinforcement ribs (8
5) may be provided (not shown). In this case, the reinforcing ribs (85)
Is parallel to the long side of the box (2). Further, in the above example, the reinforcing rib (85) extends in the vertical direction, but may extend obliquely toward the long side of the box (2).

(Second Embodiment) In this embodiment, the inside of the box (2) is characterized by a front glass plate (1) and an electrode piece (4).
The arrangement and shape of (5) are the same as in the first embodiment. FIG. 4 is a cross-sectional view of the flat fluorescent lamp according to the present embodiment, and FIG. 5 is a plan view of the box (2). On the bottom surface of the box (2), ridges (8) and (8) are arranged in a grid, and are partitioned into a pool chamber (3) to which a phosphor (7) is applied. At the periphery of the box (2), near the long side, there is formed a step surface (6) that is higher than the ridge (8), and a film of the phosphor (7) is also formed on the step surface (6). Is formed. By forming the stepped surface (6), the peripheral portion of the box (2) becomes darker than the central portion, and an optimal light emitting state can be obtained in use. This will be described in detail below.

In general, it is known that in such a flat fluorescent lamp, at the beginning of the operation, an electron flow travels along the inner surface of the box (2). It gradually becomes brighter from the periphery to the center. FIG. 6 is a plan view showing a luminance distribution at the time of completion of lighting, and the center is the brightest.
It gets darker toward the periphery. It is considered that this lighting state is desirable in actual use incorporated in an electronic device.

However, if a fluorescent lamp slightly larger than the small size is incorporated into an electronic device and turned on, a phenomenon occurs in which only the peripheral portion and the central portion of the fluorescent lamp become bright as shown in FIG. This is probably because the power supplied from the electronic device is less than a certain value, and the power supply is not sufficient for the fluorescent lamp. Can not be demonstrated. According to the experiments conducted by the applicant, a small fluorescent lamp of about 0.5 inch has a central portion of 6 inches when incorporated in an electronic device and turned on.
Illuminance of about 000 candela, but slightly larger 2.5
For fluorescent lamps of about inches, the center is 2000-3.
It was about 000 candela. The applicant has set a stepped surface on the periphery of the box (2) so that the periphery of the box (2) will not be brighter than the center of the fluorescent lamp slightly larger than the small size.
By forming (6), the gap with the front glass plate (1) was reduced. Thereby, the peripheral part of the box (2) becomes darker than the central part because of a large discharge resistance and the like, and can be suitable for an actual use state.

In the above example, the vertical and horizontal widths of the storage chambers (3) are the same, but the vertical and horizontal widths of the storage chamber (3) located at the center of the box (2) are large. Chamber located in the area
The vertical and horizontal widths of (3) may be set narrow.

The description of the above embodiments is for the purpose of illustrating the present invention and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a perspective view of a flat fluorescent lamp.

FIG. 2 is a cross-sectional view of FIG. 1 cut along a vertical plane including a line BB and viewed in a direction of an arrow.

FIG. 3 is a plan view of a box.

FIG. 4 is a sectional view of a box in another embodiment.

FIG. 5 is a plan view of the box of FIG. 4;

FIG. 6 is a plan view showing a luminance distribution at the time of lighting inside the box.

FIG. 7 is a plan view showing an undesired luminance distribution.

FIG. 8 is a cross-sectional view of a conventional flat fluorescent lamp.

FIG. 9 is a front view showing a state in which the flat fluorescent lamp is depressed at atmospheric pressure.

FIG. 10 is a front view of another conventional flat fluorescent lamp.

FIG. 11 is a plan view of the box of FIG. 10;

[Explanation of symbols]

 (1) Windshield plate (2) Box (3) Reservoir chamber (4) Electrode piece (5) Electrode piece (6) Step surface (7) Phosphor (8) Ridge (85) Reinforcing rib

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasu Nobuyasu 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Inside Sanyo Electric Co., Ltd. (72) Inventor Hiroshi Kudo 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture No. 5 Sanyo Electric Co., Ltd. (72) Inventor Masahiro Iwashita 3816, Okubo, Takaono-cho, Izumi-gun, Kagoshima 23 Inside Yamato Electronics Co., Ltd. (56) References JP-A-10-199481 (JP, A) JP-A-8 -124524 (JP, A) Hikaru 1-126053 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 61/30 H01J 61/44

Claims (3)

(57) [Claims] 1. A pair of discharge electrode pieces (4) and (5) are provided in a box (2) whose upper surface is covered with a windshield (1), and the inside of the box (2) is disposed inside the box (2). Is a flat fluorescent lamp on which a film of a dried phosphor (7) is formed. The inside of the bottom surface of the box (2) is a liquid phosphor (8) In each of the chambers (3), the surface of the phosphor (7) adheres to the ridge (8) and rises, and is separated from the ridge (8). The liquid surface is prevented from lowering under the influence of the surface tension of the container, and the reservoir chamber (3) located around the bottom of the box (2) is
(8) The box is formed by the reinforcing ribs (85) and (85) provided between (8) and (8).
A flat fluorescent lamp characterized by being partitioned into smaller sections than the storage chamber (3) in the center of (2). 2. The bottom surface of the box body (2) has a substantially rectangular shape, and the reinforcing ribs (85) are provided at least in a row of pool chambers (3) (3) located closest to the longest side. The flat fluorescent lamp according to claim 1, wherein the flat fluorescent lamp extends toward. 3. A pair of discharge electrode pieces (4) and (5) is provided in a box (2) whose upper surface is covered with a windshield (1), and is provided inside the box (2). Is a flat fluorescent lamp on which a film of a dried phosphor (7) is formed. The inside of the bottom surface of the box (2) is a liquid phosphor (8) In each of the chambers (3), the surface of the phosphor (7) adheres to the ridge (8) and rises, and is separated from the ridge (8). The liquid surface is prevented from lowering under the influence of the surface tension of the box, and the height of each ridge (8) or more is provided around the bottom of the box (2), and the phosphor (7) is provided on the top. A flat fluorescent lamp, characterized in that a step surface (6) to which is applied is formed.