JPH01114259A - Lighting device - Google Patents

Abstract

PURPOSE:To make a light quantity distribution with respect to an original surface uniform and to improve efficiency by inadiating a light flex from both end parts of a lamp on the original surface as it is and diffusing a light flux except for both end parts on a diffusing member provided between the lamp and the original surface. CONSTITUTION:The diffusing member 5 is disposed between the lamp 1 and the original surface 4. A diffusing processing 51 such as a frosted glass processing is executed on a part of a transparent glass in the diffusing member 5, and the length of the glass on which the diffusing processing is executed is set to the part of a range K equivalent to light-emitting points 12-14. Consequently, both end parts of the original surface 4 are lighted by the direct light flux from the lamp 1, and a part except for both end parts is lighted by the diffused light flux which has been diffused in the diffusing member 5. Thus, a lighting device where the light quantity distribution with respect to the original surface is mostly uniform and which has high efficiency can be obtained.

Description

Detailed Description of the Invention A. Object of the Invention [Field of Application in Industry-1-] The present invention is intended for use as an illumination device, particularly as a light source, for use as document illumination means in office equipment such as copying machines and facsimile machines. The present invention relates to a lighting device using a multi-point luminescent tubular lamp (hereinafter referred to as a lamp).

[Conventional technology]

The following points should be considered when designing a lighting device.

(1) If the lighting device is small in size, especially in the height direction, the entire main device will become large.

(2) Ability to provide highly efficient lighting. If the lighting efficiency is low, it is necessary to increase the power consumption of the lamp itself in order to obtain the required amount of light, which increases the capacity of the lamp power supply, leading to higher costs. Furthermore, the amount of heat generated increases, which requires a cooling fan, which also increases the size and cost of the entire main unit.

(3) An illumination light amount distribution as uniform as possible can be obtained over the entire required illumination area. If the illumination light intensity distribution is uneven,
If the main body device is a copying machine, for example, image density unevenness corresponding to unevenness in illumination light amount distribution occurs in the copied image, resulting in deterioration of image quality.

FIG. 9 is a perspective view showing a conventional lighting device. In the figure, 1 is a lamp, which is composed of an elongated straight glass tube 2 and a filament 10 inserted into the tube. The filament 10 has a plurality of filament winding portions 11 to 15 as light emitting points at predetermined approximately equal intervals 4 along its length,
When energized, each of the light emitting points 11 to 15 emits light, and the entire lamp functions as a linear light source lamp.

Reference numeral 3 denotes a reflecting mirror shade for condensing the luminous flux emitted from the filament 10 between the slit illumination parts 41-42 on the document surface 4 as the illuminated member, and its cross-sectional shape is similar to that between the filament 10 and the slit illumination parts 41-42. It is an elliptical mirror with a focal point near 42 mm.

In designing this lighting device, first, the unevenness of the light amount of the lamp 1 is minimized and the amount of illumination light is increased.
The dimension from the lamp 1 to the document surface 4 is determined as shown in FIG. 10(C). The light intensity distribution on the document surface with this dimension is
As shown in Figure (C), the light amount distribution e by the light emitting points 11 to 15
A total light amount distribution E is obtained from 1 to e5.

The reason why the light h1 distribution corresponding to the light emitting points 11 and 15 at both ends is large is because the number of light emitting points is smaller at both ends of the document surface compared to other areas.In other words, the luminous flux from the light emitting points 12 to 14 is effectively used at both ends of the document surface. However, at both ends, the light emitting point 1
Since there are only 1 and 12 or 14 and 15, the lengths of the light emitting points 11 and 15 at both ends are made long in advance to increase the amount of light emitted.

[Problem that the invention seeks to solve]

The conventional illumination device is constructed as shown below, so if the lamp is brought close to the primordia as shown in Figure 10(b),
The light intensity distribution between the slit illumination parts 41 and 42 is shown in Figure 11 (
As shown in b), the image becomes wavy and the amount of light becomes uneven.

Furthermore, as shown in FIG. 10(d), if a diffuser plate 51 is installed between the lamp 1 and the document surface 4 in order to alleviate the unevenness in the amount of light, the effect of the diffuser plate 5 will cause the light flux to be too diffused. Therefore, there was a problem in that the light intensity distribution on the document surface 4 deteriorated as shown in FIG. 11(d).

The present invention has been made in order to solve the above-mentioned problems, and its ``first objective'' is to provide a highly efficient illumination device with less unevenness in the light amount distribution on the document surface.

Summary: Structure of the Invention [Means for Solving the Problems] The present invention provides that the luminous flux from the light emitting parts at the ends of a multi-point luminescent tubular lamp is directed directly toward the surface of the member to be illuminated, and is shielded from the light emitting parts other than the ends. The lighting device is characterized in that a diffusion member that diffuses a light beam directed toward a surface of the lighting member is disposed between the multi-point emitting tubular lamp and the member to be illuminated.

[For production]

The illumination device according to the present invention irradiates the light beams from both ends of the lamp directly onto the document surface, and diffuses the light beams from other than both ends with a diffusion member provided between the lamp and the document surface. On the other hand, it is possible to obtain almost the same amount of light evenly.

〔Example〕

1 to 4 show a first embodiment of the present invention in which the same parts as in FIG. 9 are given the same reference numerals, and FIG. 1 is a perspective view, FIG. 2 is a front view, and FIG. is a side view, and FIG. 4 is a front view of the diffusion member.

1 to 4, reference numeral 5 denotes a diffusion member disposed between the lamp 1 and the document surface 4, and this diffusion member 5 has a part of transparent glass subjected to a diffusion treatment 51 such as frosted glass treatment. It is something. The length of this diffusion treatment is
As shown in FIG. 2, this is a portion corresponding to light emitting points 12 to 14.

Further, as shown in FIG. 3, the width of the diffusion process is the portion where the line connecting the light emitting points 11 to 15 of the lamp 1 and the document surface 4 penetrates the glass plate, and the virtual image of the lamp 1 reflected on the reflective mirror shade 3. The size may be such that it does not invade the area connecting 1 and the document surface 4.

The distance from the virtual image position of the lamp l reflected on the reflector shade 3 to the document surface 4 is as shown in FIG. 10(a).
The dimensions may be the same as those shown in Figure (C).

With the above configuration, both ends of the document surface 4 are illuminated with the direct light beam from the lamp l, and areas other than both ends are illuminated with the diffused light beam diffused by the diffusion member 5, so that the document surface 4 is almost uniform over its entire width. - Evenly illuminated at the tip.

FIGS. 5 and 6 show an example in which a diffusion member 52 having a shape in which both ends of the undiffused portion of the diffusion member 5 used in the embodiments of FIGS. 1 to 41Δ are cut off is used. The lighting system has been changed to R41, and the opening RJ area has increased, so the cooling effect has also been improved.

7 and 8 show an embodiment in which all the light beams from the lamp l and the light beams from the reflective mirror strip 3 are irradiated onto the document surface 4 via the reflective mirror strip 54. A diffuse reflection process 55 is applied to the range corresponding to the light emitting points 12 to 14. In the wooden embodiment, there is no need to provide a new diffusion member for diffusion, and by applying diffusion treatment to an aluminum plate to form the reflective mirror stripes 54, it is safe and will not break.

C. Effects of the Invention As described in -1-, according to the present invention, the light flux from the end of the multi-point luminous tube lamp is directly diffused, or the light flux from other than the end is diffused by the diffusing member, so that the original F. Since the illumination device is configured so that the illumination device 4j is irradiated with a substantially uniform amount of light on the document surface, it is possible to obtain a highly efficient illumination device.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a lighting device according to the piS1 embodiment of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a side view thereof.
Figure 4 is a front view of the diffusion member, Figure 5 is a perspective view showing the second example, Figure 6 is a front view of the diffusion member used in the second embodiment, and Figure 7 is the third embodiment. A perspective view, FIG. 938 is a front view of a diffusion member used in the third embodiment, FIG. 9 is a perspective view showing a conventional lighting device, FIGS. 1111(a) to 1111(d) are graphs showing the optical forgery distribution on the document surface for each lamp position in FIGS. 10(a) to 1111(d). 1...Multi-point luminous tubular lamp, 4...Document surface, 5.5
2.54... Diffusion member, 51.54... Diffusion treatment. Patent applicant Canon Co., Ltd. JP-A-114259 (4)

Claims (1)

[Claims] 1. A diffusing member that directs the light flux from the light emitting parts at the ends of the multi-point luminescent tubular lamp directly toward the surface of the illuminated member and diffuses the light flux from the light emitting parts other than the ends toward the surface of the illuminated member. is disposed between the multi-point luminous tubular lamp and the member to be illuminated. 2. The illumination device according to claim 1, wherein the diffusion member is a reflection member partially subjected to a diffuse reflection treatment. 3. The illumination device according to claim 1, wherein the diffusion member is a transmissive member partially subjected to a diffusion treatment.