JPH06194596A - Illuminator - Google Patents

Abstract

PURPOSE:To shorten a distance from a light source to an observed surface, to make an illuminator thin and to eliminate the unevenness of luminance on the observed surface, in the illuminator for obtaining a direct observation in such a manner that diffused light is transmitted from the rear of a transparent original. CONSTITUTION:The illuminator is composed of a box shaped device main body 7, a reflection plate 11 arranged on the bottom surface of the main body 7 and having a paraboloid, a fluorescent lamp 9 disposed in parallel with the direction of the long side of the main body 7 at the lowerest position on the reflection plate 11, a circuit 10 driving the fluorescent lamp 9 and a diffusion plate 13 arranged just above the fluorescent lamp 9 and having the observing surface 12 as the outside surface. Then, at a position nearest to the observing surface 12 on the outer periphery of the tube of the fluorescent lamp 9, a light shielding wire 9 made of a conductive coating material, etc., is provided along a longitudinal direction and constituted so as to intercept a part or the whole of a luminous flux emitted from the fluorescent lamp 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device for transmitting diffused light from the back surface of a transparent original so as to directly observe the transparent original.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, in order to directly observe a transparent original such as a color transmissive positive image such as a color reversal film or a color print film, or a color negative film, which can be observed only by transmitted light. As shown in the figure, a transparent original (not shown) placed on an observation surface 3 which is an outer surface of the diffusion plate 2 is used by using an illumination device having a light source 1 and a diffusion plate 2 which emits uniform diffused light. Irradiation of diffused light is performed from the back surface of the. Reference numeral 4 in the figure denotes a box-shaped device body that houses the light source 1.

In such an illuminating device, in order to eliminate the uneven brightness and obtain the observation surface 3 which emits a uniform diffused light, it is necessary to separate the observation surface 3 from the light source 1. When such a means is adopted, the device inevitably becomes thick, which is inconvenient for carrying around, and also the observation surface 3 becomes too high when used on a desk, so that the work posture becomes unnatural. I had no choice but to take.

Therefore, conventionally, various methods have been attempted in the illumination device for observing a transparent original in order to reduce the thickness and make the brightness of the observation surface 3 uniform. For example, as shown in FIG. 6, the thickness of the device body 4 is reduced to bring the light source 1 and the observation surface 3 closer to each other, and to prevent the luminance of the observation surface 3 from being bright when the light source 1 is close to the light source 1 and being dark from the light source. In order to protect the light, a spring 6 is provided between the light source 1 and the diffuser plate 2 forming the viewing surface 2, such as an exposed photographic film, having a light absorbing plate 5 having uneven light transmittance in each part.
The brightness of the observation surface 3 is made uniform by stretching the light transmittance at a position near the light source 1 and a light transmittance at a position far from the light source 1. Further, in recent years, instead of a photographic film, a light absorbing plate having a pattern such as a halftone dot pattern has been used so that its density increases as the distance from the light source 1 decreases.

[0005]

However, in the method using the exposed photographic film among such methods, not only the structure of the apparatus is complicated and the manufacturing cost is high, but also the light transmittance is uniform in each part. There is a problem that it is difficult to stably produce a non-photo film. Further, there is a technical problem that the performance of the manufactured photographic film changes with time due to ultraviolet rays emitted from a fluorescent lamp, heat rays, etc. and is unstable.

Further, in the case of a light absorbing plate having a halftone dot pattern, not only the manufacturing cost is high as in the case of the above-mentioned photographic film, but also dust on the surface of the light absorbing plate makes it look as if the halftone dot pattern is present. The effect is similar to that of changing the density, and there is a problem that the brightness of the observation surface is not uniform. Furthermore, it is possible to arrange multiple light sources side by side,
In that case, there are drawbacks such that the weight of the entire apparatus becomes extremely large and the manufacturing cost becomes high.

The present invention has been made to solve these problems. In an illuminating device for transmitting diffused light from the back surface of a transparent original for direct observation, the distance from the light source to the observation surface is short and thin. In addition, it is intended to make the diffused light emitted from the observation surface uniform and eliminate the uneven brightness.

[0008]

The illumination device of the present invention is a lighting device having a fluorescent lamp as a light source and having a flat surface for emitting diffused light from the back surface of a transparent original, on the outer peripheral surface of the tube of the fluorescent lamp. At the site closest to the plane,
It is characterized in that a light-shielding line that intercepts an appropriate amount of light flux is provided along the length direction.

In the present invention, the preferable thickness of the light-shielding line that partially or wholly blocks the light flux depends on the output of the fluorescent lamp and the distance from the fluorescent lamp to the diffusion plane (observation surface) that emits the diffused light. When a 10 W fluorescent lamp is used and the distance to the observation surface (the thickness of the device) is 50 mm, the thickness of the wire is preferably 3 mm ± 0.5 mm. Further, the number of such light-shielding lines is not limited to one, and a plurality of lines may be arranged on the outer peripheral surface of the tube at equal intervals.

Further, in the present invention, as a means for forming a light-shielding line at a predetermined portion on the tube of a fluorescent lamp, a light-shielding property including a conductive paint or a diffuse reflector such as magnesium oxide, titanium oxide or zinc oxide is used. There is a method of printing the paint by silk printing, a method of adhering a light-shielding member having a constant light transmittance, a method of vapor deposition of a metal such as aluminum, etc., and there is no particular limitation.

[0011]

In the illuminating device of the present invention, the light-shielding line is provided on the outer peripheral surface of the fluorescent lamp incorporated as the light source, at the portion closest to the diffusion plane (observation surface) for emitting the diffused light.
Since the light flux emitted from the fluorescent lamp in this direction is partially blocked, the part of the observation surface closest to the fluorescent lamp has a proper amount of light blocked by the light-shielding line. Receive. Therefore, even in a thin illumination device in which the distance from the light source to the viewing surface is short, uniform diffused light is emitted without uneven brightness on the viewing surface.

In addition, since the light source itself is provided with the light-shielding line having the function of assisting the diffusion ability of the diffusion plane and eliminating the uneven brightness, it is possible to secure a sufficient distance from the diffusion plane. Even if the light-shielding diffusiveness and positional precision of the line are low, a sufficient effect is exhibited and an observation surface having uniform brightness can be obtained.

Further, particularly when the light-shielding line is formed of a conductive material such as a conductive paint or an aluminum mylar film, this functions as a starting auxiliary conductor of the fluorescent lamp, and the resistance value of the glass tube wall is sufficiently increased. It keeps it small and has the effect of accelerating the lighting start time of the fluorescent lamp.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a thin lighting device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA.

As shown in these figures, the lighting device of the embodiment has a box-shaped device body 7, a fluorescent lamp 9 having a light-shielding line 8 formed on its outer peripheral surface by a conductive paint or the like, and this fluorescent lamp. It is composed of a circuit 10 for driving 9, a reflection plate 11, and a diffusion plate 13 having an observation surface 12 as an outer surface.
The device body 7 is thin (thin) corresponding to the distance from the light source to the observation surface 12, and its bottom surface efficiently reflects light other than the light flux that directly reaches the observation surface 12 and makes it uniform. For projection, a reflective plate 11 having a paraboloid is arranged with its curved inner surface facing upward. Here, as the reflection plate 11, an aluminum plate, a tin plate or the like having a high light reflectance is used, and in order to diffuse and reflect the light to make the brightness on the observation surface 12 more uniform, a satin pattern or the like is formed on the surface. Is preferably formed. In addition, such a reflector 11
Is preferably sized to cover the entire observation surface 12. A fluorescent lamp 9 is arranged at the lowest position on the reflection plate 11 in parallel with the long side direction of the reflection plate 11, and the diffusion plate 13, that is, the observation surface 12 is provided on the outer peripheral surface of the glass tube. A light-shielding line 8 that partially blocks a light beam is provided along the length direction at the closest position. Also,
Above the fluorescent lamp 9 at an appropriate distance, a diffusion plate 1 made of a diffusion and transmission member such as an opalescent resin plate.
3 is arranged and fixed to the upper edge of the device body 7.

In the illuminating device of the embodiment constructed as described above, uniform diffused light is radiated without causing uneven brightness at each position on the observation surface 12. That is, the luminance at each position on the observation surface 12 is measured in the illumination device of the embodiment, and the measurement result is plotted on the abscissa indicating the position on the observation surface 12 at the coordinates orthogonal to the fluorescent lamp 9, and the ordinate indicates the measurement result. The brightness (illuminance) at the position is shown by the solid line in FIG. For comparison, the luminance distribution at each position of the observation surface in the conventional thin illumination device is shown by a broken line in the figure.

As is clear from these brightness distribution graphs, in the conventional thin illumination device, a steep peak is formed at the center of the observation surface 12 located directly above the fluorescent lamp,
It can be seen that the brightness of this portion is remarkably increased, but in the illumination device of the embodiment, the brightness of the central portion of the observation surface 12 is suppressed by the light-shielding line 8 formed on the outer peripheral surface of the fluorescent lamp 9. In the luminance distribution, the central portion has a gentle curve, and the uneven luminance on the observation surface 12 is eliminated.

Further, in the lighting device of the embodiment, since the light-shielding line 8 is made of a conductive paint, it functions as a starting auxiliary conductor for the fluorescent lamp 9, and the lighting start of the fluorescent lamp 9 is started for the following reason. Time is accelerated. That is, in the fluorescent lamp lighting circuit 10 shown in FIG. 4, when the power supply 14 is turned on, a voltage of about 4 V is applied to the filament 17 of the fluorescent lamp 9 through the filament transformer 16 attached to the ballast 15. And filament 1
At the same time as 7 is heated, a starting voltage is applied to both ends of the fluorescent lamp 9, and a potential difference of approximately the same level is also generated between the high voltage side filament 17 and the light shielding wire 8 as a starting auxiliary conductor, and the filament 17 As the thermionic emission from the filament advances, a slight discharge is initiated between the filament 17 and the starting auxiliary conductor, and the glow discharge rapidly transitions to a complete discharge. In this way, the time required for lighting is about one second, which is much shorter than the case without the starting auxiliary conductor.

Further, conventionally, a conductive material has been used for a device for holding the fluorescent lamp 9, and this has served as a starting auxiliary conductor. In recent years, however, a non-conductive material such as synthetic resin has been used for the holding device. However, in the lighting device of the embodiment, the light-shielding wire 8 having conductivity has a start-up assisting function, so that the start-up time for lighting can be shortened. Therefore, without limiting the material of the holding device of the fluorescent lamp 9 to the conductive material, it is possible to select and design a free member.

[0020]

As described above, in the illuminating device of the present invention, even if the distance from the light source to the observation surface is small and thin, it is possible to radiate uniform diffused light without unevenness in the brightness of the observation surface. . Therefore, by transmitting such diffused light from the back side, direct observation of a transparent manuscript can be favorably carried out, and the standard as "standard illumination for color evaluation in plate making and printing" of the Japan Printing Society is Can be fully satisfied.

Further, the illuminating device of the present invention has a simple structure and can be obtained only by forming a light-shielding line on the outer peripheral surface of the fluorescent lamp, which is a light source, so that it is extremely easy to assemble and manufacture. And at no cost.

Further, when a conductive material is used as a material for forming such a light-shielding line, the light-shielding line functions as a starting auxiliary conductor of the fluorescent lamp, and has an effect of accelerating the lighting start time. .

[Brief description of drawings]

FIG. 1 is a perspective view showing a thin lighting device according to an embodiment of the present invention.

2 is a sectional view taken along line AA in the embodiment of FIG.

FIG. 3 is a graph showing the luminance distribution at each position on the observation surface in the illumination device of the example.

FIG. 4 is a diagram showing a lighting circuit of a fluorescent lamp used in the lighting apparatus of the embodiment.

FIG. 5 is a cross-sectional view showing an example of a conventional lighting device.

FIG. 6 is a cross-sectional view showing another example of a conventional lighting device.

[Explanation of symbols]

 1 ... Light source 2, 13 ... Diffusion plate 3, 12 ... Observation surface 4, 7 ... Device body 5 ... Light absorption plate 6 ... Spring 8 ... Light-shielding line 9 ... Fluorescent lamp 10 ... Drive circuit 11 Reflector 14 Power supply 15 Ballast 16 Filament transformer 17 Filament

Claims (1)

[Claims] 1. A lighting device having a fluorescent lamp as a light source and having a flat surface for radiating diffused light from the back surface of a transparent original, wherein a luminous flux is emitted to a portion of the tube outer peripheral surface of the fluorescent lamp closest to the flat surface. An illuminating device comprising a light-shielding line for blocking an appropriate amount along the length direction.