JPS59104620A - Collective optical system of copying machine - Google Patents

Abstract

PURPOSE:To eliminate an uneven intensity of illumination caused by the eccentricity of a lens at low cost by setting the position of a view field diaphragm hole in shifting in advance by a correcting quantity in the direction for offsetting an eccentric quantity of an image forming lens. CONSTITUTION:A collective optical system is constituted so that an original on an original platen 1 is irradiated by a light source 2, and its reflected light is made to form an image on a photosesntive body 6 through two image forming lenses 3, 4, view field lens 5, diaphragm 7 and a view field diaphragm 8. In case when a lens having an eccentric quantity DELTAXei is used as the image forming lens 4, when it is presumed that a diaphragm 8a of the view field diaphragm 8 positioned at (a) near the lens moves by DELTAfi at a position of a distance (b) (the photosensitive body 6), a position of the hole 8a is shifted in advance to the opposite side by interposing the moving extent DELTAfi of the distance (b) (the photosensitive body 6) and the optical axis by a correcting quantity DELTAXHi=(a+b). DELTAXei/b. In this way, the light forms an image on the photosensitive body 6, and an uneven illumination caused by eccentricity of the image forming lens is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is a method for directing reflected light from an original to be copied onto a photoreceptor.
The present invention relates to a collective optical system for correcting illuminance unevenness caused by eccentricity of the lens and fc copying in the collective optical system.

A strip lens as shown in FIG. 1 is known as a collective optical system conventionally used in copying machines. The above-mentioned collective optical system uses a light source 2 provided below the document table 1 to
A document (not shown) on a document table 1 is irradiated, and the reflected light from the document is imaged by two imaging lenses 3, 4.
The document image is guided onto a photoreceptor 6 by a field lens 5 provided between 4 and 4, and an image of the document is formed on the surface of the photoreceptor 6. Lens 5 is the same.
A lens array formed by a mold is used.

There is a brightness diaphragm Q on the top surface of the imaging lens 3 on the fcJQ Tachibanadai l side.
7, and a field stop g is provided on the field lens 5.
ing. The field stop '8 has a large number of hexagonal aperture holes 8α opened at equal intervals in the longitudinal direction.
It functions to deflect the reflected light that has been guided upward in the scanning direction. However, even if this field stop ε is provided, the uneven illuminance may not be resolved. The causes of uneven illuminance include pitch errors of each lens provided in the lens array, 1 difference in distance between lens arrays, aperture diameter and pitch error of brightness diaphragm 7, and aperture width and pitch error of field diaphragm 8. There are eccentricities such as and and/or. Among the above-mentioned causes, each error other than lens eccentricity has little effect on illuminance unevenness, and the variation itself is small, so it can usually be ignored. However, the influence of the eccentricity of the lens is large and cannot be ignored. The displacement is given by jI - CX Δxti, where jI is the illuminance unevenness and Δxgi is the relative eccentricity between adjacent lenses.

Note that C is a constant, and if the shape of the field stop is a regular hexagon with one blade on each side, the conjugate length is k 64 rus, and the number of lens rows is one, then C2 150 (%/f).

That is, when Δxti -0,1 ΔI-1.5% shows a very large value.

For example, when using an eccentric lens as shown in Fig. 2, the hexagonal aperture hole f3ct of the field diaphragm 8 located at a distance α will be 1xfi at a position a distance apart.
It causes a loss of consciousness.

α+b Also, the relationship between Δxti and 1xfi is Δxfi−Δxet
It becomes x-.

As is clear from the above, if the imaging lens is decentered, the aperture 8α of the field diaphragm 8 moves, causing uneven illuminance.

Therefore, in the future, we have attempted to correct the unevenness in illuminance due to lens eccentricity by arranging the perforations 8α of the field diaphragm 8 in advance according to the amount of eccentricity of the lens, so as to offset the amount of movement due to eccentricity. An example of this will be described in detail below with reference to FIG.

As mentioned above, when a lens with an eccentricity of Δxei is used as an imaging lens, the aperture hole 8α of the field stop 8 located at a position α from the lens moves by Δfi.
When using a lens having a similar eccentricity to this as the imaging lens 4, the position of the aperture hole 8α of the field diaphragm g combined with this imaging lens 4 is adjusted by a correction amount Δ
The optical axis 4I is shifted in advance to the opposite direction by 11tl between the amount of movement 1xfi on the X flood and the distance.

The correction amount 1x11i is 1xHt, -” Δxi I want to steal something from someone.

With this method, the aperture hole 8α at a distance α is aligned with the optical axis 4 of the imaging lens 4. The image is formed over the entire distance, and it becomes possible to correct uneven lighting due to eccentricity of the 7th lens 4.

As described in detail above, this invention eliminates the eccentricity of lenses that occur during manufacturing by shifting the position of the aperture hole of the optical aperture used in combination with these lenses in a direction that offsets the amount of eccentricity. By correcting this, it is possible to eliminate uneven illuminance due to eccentricity of the lens, and it can also be implemented at low cost since it can be corrected simply by changing the arrangement of the field stop.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the assembly optical system, FIG. 2 is an explanatory diagram of uneven illuminance caused by eccentricity of the lens, and FIG. 3 is an explanatory diagram illustrating the one-shot arrangement of the present invention. 3.4 is an imaging lens, 5 is a field lens, 8 is a field diaphragm, and 8α is an aperture hole. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Ryo Masaaki Ki Akira 9P Attorney Tadashi Hamamoto 1 Figure 2 Figure 3

Claims (1)

[Claims] A plurality of imaging lenses 3, 4 in which a plurality of lenses 31..., 41... are arranged on a straight line, and a field of view provided between the imaging lenses 3, 4. Provided on the lens 5 and the field lens 5, and each lens 3m..., 4□.
In a collective optical system consisting of a field diaphragm 8 with aperture holes 8α opened at an equal pitch of . . . 15 + .
A collective optical system for a copying machine whose aperture is shifted in advance by Ij positive desire ΔxHi in the direction of canceling i'fr.