JPS5848663Y2 - lighting equipment - Google Patents

Description

[Detailed description of the invention] This invention relates to a lighting device incorporated into a copying machine, etc.
In particular, the present invention relates to an illumination device that exposes a document placed on a document table to slit light.

This type of lighting device, which is generally incorporated into copying machines,
It is configured as shown in the figure, with a light source 1 and an elliptical reflector 2.
The illumination optical system 3, in which the
The upper document is scanned with slit exposure.

This illumination device can obtain high illuminance because the illumination optical system 3 is close to the document surface on the document table 4, but when moving and scanning the illumination optical system 3, the movement stroke is large and the copying speed is It was difficult to improve.

When the copying speed is increased, the moving speed of the illumination optical system is also high, and the light source is likely to be damaged or disconnected, which may significantly shorten its lifespan.

For this reason, as shown in FIG. 2, there is an illumination device in which the illumination optical system 5 is fixed and the scanning reflection mirror 6 is moved to scan the document on the document table 7 by slit exposure scanning.

In this type of illumination device, the movement stroke of the scanning reflector 6 is as small as 4-L (L is the total length of the document table), and it is suitable for high-speed illumination scanning and even high-speed copying, but the distance from the illumination optical system 5 to the document surface is small. is large, and when exposing the document surface to slit light,
In some cases, the amount of light is insufficient, or in order to obtain a sufficient amount of light, a large-capacity light source must be used in the illumination optical system 5.

This invention takes the above-mentioned points into account, and aims to provide an illumination device that can perform slit exposure scanning with a sufficient amount of light without impairing the life of the light source and is suitable for high-speed illumination scanning.

Embodiments of the lighting device according to this invention will be described below with reference to the accompanying drawings.

In FIG. 3, reference numeral 10 indicates a lighting device incorporated into a copying machine or the like.

This lighting device 10 includes a light source 11 and a main elliptical reflecting mirror 12.
The main illumination optical system 13 has a main illumination optical system 13 that integrally incorporates the main illumination optical system 13, and an exposure illumination optical system 15 that slit-exposes the illumination light from the main illumination optical system 13 onto a document (not shown) on a document table 14.

The main illumination optical system 13 is linked with the exposure illumination optical system 15 and is provided movably along a common inclined line (2) forming an angle θ with respect to the horizontal direction.

The exposure illumination optical system 15 includes a scanning reflector 16.

On the other hand, the light source 11 of the main illumination optical system 13 is arranged at one focal point of the elliptical reflector 12, while the scanning reflector is arranged so that the other focus of the elliptical reflector 12 is located on the document surface on the document table 14. Adjustments are made at 16.

Therefore, the illumination light from the light source 11 is reflected by the elliptical reflecting mirror 12, then passes through the scanning reflecting mirror 16, and is focused onto the document surface on the document table 14, where it is scanned with slit exposure.

Next, the lighting principle of this lighting device 10 will be explained.

As shown in FIG. 4, the total length of the document table 14 is L, the angle of incidence of illumination light on the document table 14 is α, and the distance from the light source 11 to the scanning reflector 16 at the initial illumination position is C1. Let S be the optical path length from 16 to a predetermined point P.

At this predetermined point P, the reflected light from the scanning reflector 16
This is the point where it intersects with L.

This straight line SL is a straight line that passes through the center of the scanning reflecting mirror 16 and is parallel to the document table 14 when the scanning reflecting mirror 16 assumes the illumination end position.

The distance from the document table 14 to the straight line SL is d.

Thus, the moving speed ratio of the main reflecting mirror 12 of the main illumination optical system 13 and the scanning reflecting mirror 16 of the exposure illumination optical system 15, which move in conjunction, is determined.

First, when the illumination light from the main illumination optical system 13 scans the document surface on the document table 14 with slit exposure from A to B, let the moving amounts of the main reflecting mirror 12 and the scanning reflecting mirror 16 be LMI and M2. LMl−LM2 10 −(c + e) =−・
-(i) (where t is the vertical distance from the initial illumination position of the scanning reflector 16 to the document table 14.

).

The moving amounts LMI and LM2 of both reflecting mirrors 12 and 16 are generally smaller than the length of the document table.

On the other hand, since LM2Sinθ=td, equation (2) is derived.

Furthermore, the moving speed ratio between the main reflecting mirror 12 (main illumination optical system 13) and the scanning reflecting mirror 16 (exposure illumination optical system 15) is expressed by the ratio of the moving amounts LMI and LM2 of both reflecting mirrors 12.16. , becomes.

Here, since S is (t d)/cos α, substituting equation (3) into equation (4) gives the following equation, and the moving speed ratio becomes constant and is expressed as a function of angles θ and α.

From equation (5), it can be seen that the moving speed and amount of movement of the main reflecting mirror 12 are smaller than those of the scanning reflecting mirror 16.

Furthermore, the optical path length (constant) of the illumination light from the light source 11 of the main illumination optical system 13 to the document surface on the document table 14 is shorter than the optical path length shown in FIG. Can be scanned.

At this time, since the amount and speed of movement of the light source 11 of the main illumination optical system 13 are small, it is possible to prevent the light source 11 from being damaged or disconnected, and to effectively prevent its lifespan from being shortened.

Furthermore, since the main illumination optical system 13 and the exposure illumination optical system 15 can be reciprocated and scanned with a stroke smaller than the length L of the document table 14, it is suitable for high-speed illumination scanning.

As described above, in the illumination device according to this invention, the movement stroke of the main illumination optical system and the exposure illumination optical system that move in conjunction is small, so it is suitable for high-speed illumination scanning, and even when high-speed illumination scanning is performed. Damage to the light source and disconnection can be effectively prevented, and reduction in its lifespan can be reliably prevented.

Furthermore, since the optical path length of the illumination light from the light source of the main illumination optical system to the document surface on the document table is short, it is possible to perform slit exposure scanning of the document surface with a sufficient amount of light.

[Brief Description of the Drawings] Figures 1 and 2 are schematic diagrams showing a conventional lighting device, Figure 3 is a diagram showing an embodiment of the lighting device according to this invention, and Figure 4 is a diagram showing an embodiment of the lighting device according to this invention. FIG. 3 is a diagram showing the lighting principle of the lighting device. 10...Lighting device, 11...Light source, 1
2...Main elliptical reflecting mirror, 13...Main illumination optical system, 14...Document stand, 15...Exposure illumination optical system, 16... ...Scanning reflector.

Claims (1)

[Scope of utility model registration request] 1. It has a main illumination optical system that combines a light source and a main reflection mirror, and an exposure illumination optical system that includes a scanning reflection mirror for scanning the illumination light from the main illumination optical system onto a document on a document table by slit exposure. In the illumination device, the main illumination optical system and the exposure illumination optical system are provided so as to be movable in conjunction with each other in an oblique direction forming a predetermined angle with respect to the horizontal direction, and the amount of movement of the main illumination optical system is equal to the movement of the exposure illumination optical system. A lighting device characterized by being smaller than the amount of light. 2. When the main illumination optical system and the exposure illumination optical system move along a common inclined line that forms an angle θ with the horizontal direction, the incident angle of the illumination light on the document table is α, and the movement is constant. The illumination device according to claim 1, which is configured to move in conjunction while maintaining a speed ratio of 5 int)' ccsα. 3. The main reflecting mirror of the main illumination optical system is an elliptical mirror, and the light source is placed at one focal point, while the exposure illumination optical system scans so that the other focal point is located on the document surface on the document table. The illumination device according to claim 1 of the utility model registration, in which the reflecting mirror is adjusted and set.