JPS605934B2 - Original illumination method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to illumination systems and specifically to slit exposure document illumination systems.

Conventionally, the following two methods have been used to illuminate the document surface using slit exposure.
Two methods are commonly used. That is, 'a) A method in which a light source and a reflector are moved parallel to the document surface to scan the entire scanning range to illuminate the document surface (see FIG. 1). In the figure, 1 is a light source, 2 is a reflector, 1' is a light source at a moved position, 2' is a reflector at a moved position, and 3 is a document surface.

'b} A method of illumination scanning by fixing the light source and reflector and swinging the other reflecting mirror (see Figure 2).

In the figure, 4 represents a reflecting mirror, and 4' represents a swung reflecting mirror.

However, in method [a], it is difficult to increase the speed because the light source and reflector are moved and scanned over the entire area of the document.

The reason for this is that a driving source with a large output is required.In addition, in method [b--, the light source and Because the reflector is fixed (although the drawbacks of method a) are avoided), because the reflecting mirror oscillates, the distances from the center of oscillation to each layer on the document surface are different. As a result, the illuminance and its distribution change depending on the position of the document surface, and there is a drawback that the document information cannot be faithfully exposed.The present invention was made to overcome the above-mentioned drawbacks of the conventional illumination method of this type. It is something.

An object of the present invention is to provide a high-speed exposure illumination method by fixing the light source and reflector and reducing the moving distance and speed of the moving part.

Another object of the present invention is to provide an illumination method in which the distance from the light source is the same at any position on the document surface, and the light condensing conditions are constant. The above object of the present invention is achieved by positioning the reflecting mirror on the perpendicular bisector of a straight line connecting the document reading position and the light source convergence point and causing the reflecting mirror to move linearly and swing. The invention will now be described with reference to the accompanying drawings, in which preferred embodiments thereof are shown.

FIG. 3 is a schematic diagram for explaining the principle of this system.

In the figure, 1 is a light source, 2 is a reflector, 3 is a document surface,
4 is a reflecting mirror, 5 is an imaging lens, and 6 is a photosensitive drum. The focal point of the light source when there is no reflection mirror 4 is o
, the manuscript reading start point is o', the manuscript reading end point is o'',
The perpendicular bisector of the straight line connecting points o and o' is p'm', and point o
, o'' is the perpendicular bisector of the straight line p″m″,
△oo′m′ and △oo″m′′ are oo′ and oo, respectively.
The base is an isosceles triangle, and the points o and o' are p
There is a relationship of line symmetry with 'm' as the axis of symmetry, and the points o and o
'' have a line-symmetrical relationship with p''m'' as the axis of symmetry. Therefore, if the reflecting mirror 4 is placed on the straight lines Pm' and p''m'', the condensing points of the light source 1 will be o' and o'', respectively. This allows the light source to be focused at the reading position. By maintaining the same relationship at the reading position between points o' and o'', the light source light can be focused on the document surface.
Exposure in which document information is exposed onto the photoconductor drum by moving the imaging lens 5 parallel to the document surface 3 and scanning the photoconductor drum 6 placed at the imaging position in synchronization with the imaging lens 5. A scanning method is achieved. A specific embodiment in which the reflecting mirror 4 is caused to perform linear motion and oscillating motion is shown in FIG.

In the figure, 7 is a guide surface, 8 is a guide rod, 9 is a moving body, 1
0 is a guide roller and 11 is a spring. A guide bar 8 arranged parallel to the center line of the east illumination light, a movable body 9 guided by the guide rod 8, a reflecting mirror 4 rotatably mounted on the movable body 9, and a reflecting mirror 4 that is rotatably mounted on the movable body 9. A guide held integrally with the mirror 4. -La 10 and
As the movable body 9 moves while contacting this guide roller, the distance from the guide group changes, and the guide surface 7 and the guide roller 1 give a swinging motion to the reflecting mirror 4 according to the moving distance.
0 is always in contact with the guide surface 7, and by moving the movable body 9 while maintaining the above-mentioned relationship, it is possible to concentrate the light source light at the reading position. . In addition, the reflected light can be best focused by making the optical path length from the light source 1, through the reflecting mirror 4, to the kendori starting position o' equal to the distance between the focal points of the reflector 2, and by making it different to some extent. It is also possible to provide a suitable slit inside, thereby facilitating adjustment of other optical systems.

In either case, it is possible to layout the slit so that it does not change during scanning or changes as desired. In summary, according to the present method, an illumination method that requires only a small moving distance and can always focus light on the document collection position can be obtained, and moreover, it is possible to perform high-speed and faithful exposure scanning.

In the embodiment shown in FIG. 4, the guide rod 8 is arranged parallel to the main light from the light source, but it goes without saying that the same relationship can be maintained even if the guide rod 8 is not particularly parallel.

Further, the guiding means for the reflecting mirror 4 is not limited to the one shown in FIG. 4, but may be a conventionally known guide means that gives the reflecting mirror an inclination of an amount corresponding to its linear momentum, that is, the amount of movement while making a linear movement. A similar effect can be achieved by using means such as a cam mechanism, link mechanism, gear mechanism, or electrical control method that detects the amount of movement and changes the magnetic field to change the momentum according to the magnetic flux to swing the reflecting mirror. I can do it.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams for explaining the conventional document surface illumination method, FIG. 3 is a schematic diagram for explaining the principle of the illumination method according to the present invention, and FIG. 4 is a schematic diagram for explaining the principle of the illumination method according to the present invention. FIG. 2 is a schematic diagram showing an embodiment of the invention. 1... light source, 2... reflector (reflector)
, 3... Original surface, 4... Reflecting mirror,
5... Imaging lens, 6... Photosensitive drum, 7... Guide surface, 8... Guide bar, 9
...Moving body, 10...Guide roller, 11...
...Spring. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. Making a reflecting mirror move linearly and oscillatingly while maintaining a relationship such that the reflecting surface lies on the perpendicular bisector of a straight line connecting the document reading position and the light source convergence point. A manuscript illumination method featuring 2. The document illumination method according to claim 1, further characterized in that the optical path length from the linear light source to the document surface via the reflection mirror is made equal to the focal length of an ellipse including the reflection surface of the light source reflector. . 3. The document illumination method according to claim 1, further characterized in that the optical path length from the linear light source to the document surface is slightly shifted from the focal length of an ellipse including the reflective surface of the light source reflector.