JPH04141946A - Cold cathode fluorescent discharge tube - Google Patents

Abstract

PURPOSE:To shorten the length of a discharge tube, and to ensure a preset amount of equal lighting length by making the center part of the width of an aperture linearly provided in the longitudinal direction of the discharge tube relatively thin, and by making the vicinity of both ends thick. CONSTITUTION:An aperture (a window provided for removing a phosphor, and for effectively extracting the light) 3 is provided on the extraction side of quantity of light, while a reflecting part is provided on the reverse side. The aperture 3 can be provided linearly on the tube inner wall in the longitudinal direction of a fluorescent discharge tube 1, and the width of the center part can be thick while the vicinity of both ends is thick, or the aperture 3 can be provided only in the vicinity of the both ends, and not in the center. For example, the width d2 in the vicinity of both ends is 2-5, or preferably 3-4, when the width d1 in the center part is 1. The width in the vicinity of both ends can be equal or can be thicker in the front end. The length of the tube can be shortened without sacrificing an equal lighting length.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cold cathode fluorescent discharge tube, particularly to a cold cathode fluorescent discharge tube useful as a light source for a life-size scanner.

[Prior art]

A variety of light sources are used in life-size scanners, including fluorescent lamps, halogen lamps, discharge tubes, and LED arrays, and various technologies have been developed to uniformly illuminate the sensor with light from these light sources. There is.

Many methods have been introduced as means for dimming LED arrays, such as a method of individually controlling the resistance of each LED, and a method of providing a reflection means near the LED chip as shown in Japanese Patent Laid-Open No. 60-147177. ing.

This is because the LED array was considered to be effective in reducing size, which is one of the major advantages of full-size scanners.

However, a method for controlling the light intensity distribution when using a linear discharge tube such as a xenon lamp is disclosed in Japanese Patent Application Laid-Open No. 63-310.
No. 261, JP-A-63-310262, JP-A-63-
As shown in Japanese Patent No. 310263, only a few devices have a mesh-like light control member inserted between a light source and a light sensor, and the reality is that they have not been developed much.

In recent years, cold cathode xenon fluorescent discharge tubes have become smaller, with tube diameters of 41 mm or less, and can produce 5 to 10 times more light than LEDs, so they are being reconsidered as light sources for 1-magnification scanners. There is a problem in that the amount of light inevitably decreases near both ends. Therefore.

It was necessary to use a tube longer than the required tube length as a light source, and to use only the portion where the light intensity would not decrease. FIG. 1 shows the light intensity distribution in the tube length direction of a conventional cold cathode xenon fluorescent discharge tube 1, and shows that when the tube length is 260 m and the electrode length is 240 cm, the average illumination length is 2201 mm. Moreover, this FIG. 1 shows the light amount distribution necessary for a full-size scanner compatible with A4 paper. The size of A4 paper is approximately 2 in the width direction
1 Ona, and taking into account setting errors during paper feeding, paper feeding errors, etc., it is necessary to ensure an average illumination length of about 220 frames.

The method for measuring the amount of light is as shown in FIG. 3, by placing a light amount sensor 2 at a position 4N from the upper surface of a cannon tube 1 (hereinafter abbreviated as Xe tube) and observing its output. In FIG. 3, 3 is an aperture, 4 is a tube wall, 5 is a phosphor, and 6 is a back electrode. The back electrode usually has a width of about 1 mm and a thickness of 0.1 mm or less.

Pipe length of conventional cannon tube 1 shown in Figure 1 (260 m)
If you shorten it to 238■, the average lighting length will be about 200 kakus. Therefore, we wanted to ensure a uniform illumination length of 220 m, so the tube length remained at 238 nn and the electrode length was changed by 2.
Assuming 27 cabinets, the uniform lighting length can only be improved to 210cm. Figure 2 shows the results, and further improvements were needed.

Here, we will consider the fact that the average illumination length is shorter than the electrode length (emission length).

As shown in Figure 19, a normal cold cathode discharge tube is a uniform light source, and the amount of light emitted at each position (indicated by the length of the upward arrow in the figure) is the same, but the light receiving end The amount of light received differs between the LA area and the central LB area.

As shown in FIGS. 21 and 22, in the L9 region, light comes from the left and right sides in addition to the downward direction, but in the LA region, light comes only from the right direction in addition to the downward direction. For this reason, the amount of light received in the LA area is less than the amount of light received in the area, resulting in a profile as shown in FIG. 20.

Generally, when a surface light source as shown in FIG. 25 exists, the illuminance E at a point P below the single surface light source can be expressed as shown in the following equation. Note that B in the formula represents brightness.

Therefore, if we increase the amount of light emitted at both ends as shown in FIG. 23, we can achieve L as shown in FIG. 19! l area (LD area in Figure 23)
The amount of light received in the LA area (in Figure 23, L
The present invention was completed based on the idea that the amount of light received in the c region could be increased and the profile shown in FIG. 24 could be achieved.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a cold cathode fluorescent discharge tube whose length is shorter than that of conventional cold cathode fluorescent discharge tubes and which ensures a predetermined uniform illumination length.

In other words, the present invention is characterized by relatively increasing the amount of light emitted at both ends, specifically.

■) Increase the light intensity by widening the apertures at both ends of the cold cathode fluorescent discharge tube, 2) Increase the light intensity by installing reflective paint or reflectors at both ends of the cold cathode fluorescent discharge tube. For example, even if the tube length of the Xs tube is 2401 or less, the average illumination length is 2
By carrying out the present invention, it is possible to provide a cold cathode fluorescent discharge tube exhibiting the profile shown in FIG. 4.

〔composition〕

The first aspect of the present invention is a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with a phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends. The present invention relates to a cold cathode fluorescent discharge tube characterized in that the width of the aperture linearly provided in the longitudinal direction of the fluorescent discharge tube is relatively narrow at the center and wide near both ends.

The second aspect of the present invention is a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends. The present invention relates to a cold cathode fluorescent discharge tube characterized in that an aperture is provided only near both ends of the fluorescent discharge tube.

The third aspect of the present invention is a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with a phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends. 6 books related to cold cathode fluorescent discharge tubes, characterized in that the width of the reflective part provided linearly on the outer wall of the tube in the longitudinal direction of the fluorescent discharge tube is relatively narrow in the center and thick in the vicinity of both ends. Fourth invention
is a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends. The present invention relates to a cold cathode fluorescent discharge tube characterized in that a reflective section is provided only on the outer wall of the tube near the section.

A fifth aspect of the present invention is a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with a phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends. an aperture that is linear in the longitudinal direction of the fluorescent discharge tube and whose width is relatively narrow in the center and thicker near both ends; and an aperture that is linear in the longitudinal direction of the fluorescent discharge tube and has a width thereof The present invention relates to a cold cathode fluorescent discharge lamp characterized in that it is provided with a reflecting portion that is relatively thin at the center and thick near both ends.

In the present invention, the aperture is provided on the light amount extraction section side, and the reflection section is provided on the opposite side to the light amount extraction section side. Further, the portions near both ends are 20% or less of the entire length of the pipe.

It usually means about 15 to 7%.

Regarding the widths of the aperture and the reflecting section, if the width at the center is 1, the width near both ends is 2 to 5, preferably 3 to 4. Further, the width near both ends may be uniform, or may become thicker toward the tip.

Examples of the rare gas include xenon, krypton, and argon, and the pressure inside the tube is preferably 1 atmosphere or less.

Next, the aperture and the reflection section will be explained with reference to the drawings.

1) Regarding the aperture (corresponding to claims 1 and 2) In a cold cathode fluorescent discharge tube, the aperture is formed in a straight line along the inner wall of the fluorescent discharge tube in the longitudinal direction of the fluorescent discharge tube, and is relatively narrow in the center and near both ends. Either it should be provided so that it is thicker, or it should not be provided in the center but only near both ends.

For example, as shown in the cross-sectional view of the Xe tube 1 in FIG. 3, in the Xe tube 1 in which a part of the phosphor 5 on the light output side is removed and an aperture 3 is provided, As shown in FIG. 7 when viewed from the input direction, a profile as shown in FIG. 4 can be obtained by gradually increasing the width of the aperture parts near both ends, which are narrow at the center and toward both ends.

Further, as shown in FIG. 13, a profile as shown in FIG. 4 can be obtained even when the width of only a portion of the aperture near both ends is uniformly widened.

Another example is a shape in which the aperture is not provided in the center but only in the vicinity of both ends, as shown in FIG. 8, where the width gradually increases toward both ends; As shown, the profile shown in FIG. 4 can also be obtained by providing apertures of appropriate uniform width near both ends.

The shape of the aperture is not limited to the above example, but it is possible to take a profile as shown in FIG. 4 by considering the aperture dimensions.

2) Regarding the reflective part (corresponding to claims 3 and 4) In a cold cathode fluorescent discharge tube, the reflective part extends linearly along the outer wall of the fluorescent discharge tube in the long axis direction, and has a width that is relatively narrow at the center. It is provided so that it is thicker near both ends, or it is provided only near both ends without being provided in the center.

The reflectance of the reflective part should be 30% or more, preferably 5
It is preferably 0% or more, particularly preferably 70% or more.

a) When using paint as a reflecting means, for example, as shown in the cross-sectional view of the Xe tube 1 in FIG. As shown in Fig. 9 when viewed from the direction of arrow B in Fig. 5, the profile shown in Fig. 4 can be obtained by thinning the center part and gradually widening the paint near both ends toward both ends. . Further, as shown in FIG. 15, even if the width of the paint near both ends is uniformly widened, a profile as shown in FIG. 4 can be obtained.

Another example in which reflective paint is applied only near both ends without providing reflective paint in the center is a shape in which the width gradually increases toward both ends as shown in Figure 10, and as shown in Figure 16. As shown, a profile as shown in FIG. 4 can be obtained by applying paint to an appropriate uniform width near both ends.

The shape after the paint is applied is not limited to the above example, and various shapes can be adopted, and the important thing is to have a profile as shown in FIG.

The material used for the paint is preferably pigment-based, but examples include dye-based and silicone rubber-based.Also, white is desirable as the color of the paint, but white-based colors (e.g. cream, pale, etc.) are preferable. (e.g., gray) can be sufficiently effective. In addition to paints, metals (zinc,
Processes such as tin, nickel, chromium, etc.), vapor deposition (aluminum, chromium, silicon, gold, platinum, etc.) can be used.

b) When using a reflector as a reflection part, as an example of using a reflector, as shown in FIG. 6, in the Xe tube 1 in which a reflector 8 is provided on the outer wall of the tube 4, arrow B in FIG. As shown in Fig. 11 when viewed from the direction, the center part is narrow and the width of the reflector near both ends is uniformly widened, or as shown in Fig. 17, the reflector near both ends is gradually expanded toward both ends. When the width is widened, a profile as shown in Fig. 4 can be obtained.

As another example, a reflector is provided only near both ends without providing a reflector in the center, as shown in Fig. 12, with an appropriate uniform width provided near both ends, or as shown in Fig. 18. As shown, the reflective plates near both ends are gradually widened toward both ends, resulting in a profile as shown in FIG. 4.

The shape of the reflector is not limited to the above example, and various shapes can be adopted in consideration of the material, etc. For example, the reflector 8 may be placed in close contact with the outer wall of the pipe as in the case of the paint 7 in Fig. 5. The important thing is to take a profile as shown in Figure 4.

The materials used for the reflector include Teflon, polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyacetal (POM), engineered plastics such as liquid crystal polymers, metals such as aluminum and brass, or materials coated with paint. Examples include those processed by plating, and those processed by vapor deposition.

Further, it is preferable that the color of the reflector used is white, but a white-based color (for example, cream color, pale gray, etc.) can be sufficiently effective.

It goes without saying that the reflector described above can function not only as a reflector but also as a holder for the Xe tube.

3) Regarding the combination of the reflecting means and the aperture (corresponding to claim 5) Although the effect can be obtained by combining the shape of the aperture 3 and the shape and material of the reflecting means (the reflecting plate 8 and the paint 7) as they are, Sometimes the light intensity at both ends becomes too high. This can be handled by changing the shape of the aperture and the material and shape of the reflecting means.

For example, as shown in FIG. 26, the aperture 3 is made longer than the reflector 8 (or the paint 7), and there are areas without an aperture, areas with only an aperture, and areas with an aperture plus reflector (
It is a good idea to adjust the light intensity on the part (or paint).

In addition, as shown in FIG. 27, the reflector 8 (or paint 7)
be longer than aperture 3, and include areas without a reflector (or paint), areas with only a reflector (or paint), and areas with a reflector (
Or paint) + aperture to adjust the light intensity. 28(a) to (C) show an example in which the length of the aperture 3 and the reflecting plate 8 (or paint 7) are the same, where (a) is a cross-sectional view, (b) is an arrow A, and (c) is a cross-sectional view. shows the state seen from the direction of arrow B.

〔Example〕

In the following embodiments, the average illumination length is set to be 220 m or more since it is compatible with A4 paper, but the present invention is applicable not only to a full-size scanner that can handle A4 paper, but also to 260 m if it is compatible with 84 paper.
It is compatible with all sizes, such as 7OS and above, and 307- and above for A3 paper.

The Xe tubes used in the experiment had a diameter of 4 mφ and a length of 2.
It has a length of 38 m and an electrode length of 227 square meters.

Example 1 The one with the aperture shape shown in Figure 7.

Example 2 The one with the aperture shape shown in Figure 8.

Example 3 The paint has the shape shown in Figure 9.

Paint used: Pigment margin paint Paint reflectance = 70% Example 4 The paint has the shape shown in Figure 10.

Paint used: Pigment margin paint Paint reflectance near 0% Example 5 The shape of the reflector plate shown in FIG.

Reflector material: Teflon Reflectance of reflector: 50% Example 6 The shape of the reflector plate shown in FIG.

Material of reflector: Teflon Reflectance of reflector: 50% Based on the results, it was possible to obtain an average illumination length of 220 cm or more with cold cathode xenon fluorescent discharge tubes with a tube length of 238 cm and an electrode length of 227 cm.

〔effect〕

In the cold cathode fluorescent discharge tube according to claims 1 and 2, the width of the aperture provided linearly on the inner wall of the tube in the longitudinal direction is relatively narrow in the center and wide in the vicinity of both ends, or By having no aperture in the center and providing apertures only near both ends, the length of the tube can be shortened without compromising the uniform illumination length. In the cold cathode fluorescent discharge tube according to claims 3 and 4, the width of the reflecting means such as reflective paint or reflecting plate provided in a straight line on the outer wall of the tube in the longitudinal direction is relatively narrow in the center and wide in the vicinity of both ends. Or, by providing reflective means only near both ends without providing reflective means in the center,
The tube length can be shortened without compromising the uniform illumination length.

[Brief explanation of drawings]

Figure 1 shows the light intensity distribution in the tube length direction of a conventional cold cathode xenon discharge tube. 260mm, electrode length 2
When it is 40■, it means that the length of the uniform is 220. Figure 2 shows the tube length of a conventional cold cathode xenon discharge tube of 238 mm.
-, and shows the light amount distribution when the electrode length is widened as much as possible to 227 cm. FIG. 3 shows a cross section of the Xe tube, and the light amount sensor is installed at a distance of 4 cm from the surface of the Xe tube. FIG. 4 shows the light intensity distribution of the cold cathode xenon discharge tube according to the present invention, and the light intensity at both ends is higher than that of the conventional tube. FIG. 5 shows the position of the reflective paint (reflector plate) in a cross-sectional view of the Xe tube. FIG. 6 shows the position of the reflector in a cross-sectional view of the Xe tube. FIG. 7 shows an example of the Xe tube of the present invention, in which the center part is narrow and the apertures near both ends gradually widen toward both ends, as viewed from the direction of arrow A in FIG. 3. There is. FIG. 8 shows another example of the Xe tube of the present invention, which does not have an aperture in the center but has apertures only near both ends, and the apertures gradually widen toward both ends. It shows the state seen from six directions of arrows. Figures 9 and 10 show Xe of the present invention with paint applied to the outer wall of the tube.
The example of a tube is shown in the direction of arrow B in Figure 5. Figure 9 shows the paint near both ends gradually increasing in width as it goes towards both ends, and Figure 10 shows the paint in the center. This figure shows one in which no reflective paint is provided, and the reflective paint is provided only near both ends, and the width gradually increases toward the WJ ends. 11 and 12 show an example of the Xe tube of the present invention in which a reflector is provided on the outer wall of the tube, as seen from the direction of arrow B in FIG. FIG. 12 shows a structure in which only the reflector plate is expanded, and the reflector plate is not provided in the center, but only in the vicinity of both ends. 13 to 18 show examples of Xe tubes according to the present invention that are different from those shown in FIGS. 7 to 12, and only one side of the Xe tube is shown. is shown in Fig. 8, and Fig. 15
The figure is shown in Fig. 9, Fig. 16 is shown in Fig. 1O, and Fig. 17 is shown in Fig. 1.
1, and FIG. 18 correspond to FIG. 12, respectively. Figures 19 and 20 show the characteristics of conventional cold cathode discharge tubes, where the length of the arrow represents the amount of light emitted, and the LA area in the top view and the position represented by the area correspond to each other. Figure 19 shows a uniform amount of light emitted from a cold cathode discharge tube, which is a uniform light source, and is received by a light amount sensor, and Figure 20 shows the distribution of the amount of light. be. Figures 21 and 22 show the state in which the sensor receives light from a uniform light source, and the arrows indicate the direction of the light.
Figure 21 shows the light reception state of the sensor located in the LA area in Figure 19. Since the uniform light source exists only below and on one side, the amount of light received is lower than that of the sensor located in the Lll area in Figure 19. It shows that there are few
Figure 22 shows the light reception state of the sensor located at the Ls area position in Figure 19. Since the uniform light source is below and on both sides, the amount of light received is greater than that of the sensor located at the LA area position in Figure 19. It shows. Figures 23 and 24 show the characteristics of a light source with increased light intensity at the surface edge. The length of the arrow represents the amount of light emitted, and the positions of the Lc region and LD region in the surface view correspond to each other. FIG. 23 is a diagram in which a light amount sensor receives the amount of light from a light source with increased light amount at both ends, and FIG. 24 shows the distribution of the amount of light. FIG. 25 is a diagram showing a state in which light emitted from an aXb surface light source is received at a position P vertically spaced apart by d from the end of the surface light source. FIG. 26 shows a combination of an aperture and a reflector (or paint), FIG. 27 shows another combination, and FIGS. 28(a) to (C) show other combinations. (a) is a cross-sectional view, (b) is an arrow A,
(c) shows the state seen from the direction of arrow B. 1...Cold cathode xenon fluorescent discharge tube 2...Light level sensor 3...Aperture 4...
・Tube wall 5...phosphor 6...back electrode
7...Paint 8...Reflector

Claims (1)

[Scope of Claims] 1. In a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with a phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends, The width of the aperture (window provided to remove the phosphor and efficiently extract light) provided linearly in the long axis direction of the fluorescent discharge tube is relatively narrow in the center and wide in the vicinity of both ends. A cold cathode fluorescent discharge tube characterized by: 2. In a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends, both ends of the fluorescent discharge tube A cold cathode fluorescent discharge tube characterized by having an aperture only in the vicinity of the tube. 3. In a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends, the length of the fluorescent discharge tube is 1. A cold cathode fluorescent discharge tube, characterized in that the width of the reflecting section provided linearly on the outer wall of the tube in the axial direction is relatively narrow at the center and wide near both ends. 4. In a cold cathode fluorescent discharge tube in which a part or all of the tube wall inside the transparent tube is coated with phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends, both ends of the fluorescent discharge tube A cold cathode fluorescent discharge tube characterized in that a reflective section is provided only on the outer wall of the tube near the section. 5. In a cold cathode fluorescent discharge tube in which part or all of the tube wall inside the transparent tube is coated with phosphor, a rare gas is sealed in the tube, and electrodes are sealed at both ends, the length of the fluorescent discharge tube is an aperture that is linear in the axial direction and whose width is relatively thin at the center and thick near both ends; and an aperture that is linear in the outer wall of the fluorescent discharge tube in the longitudinal direction of the tube and whose width is relatively central 1. A cold cathode fluorescent discharge tube, characterized in that it has a reflecting section that is thinner at the end and thicker near both ends.