JPH0284866A - Adhesive type image sensor - Google Patents

Abstract

PURPOSE:To attain the deflection correction of a rod lens array by providing an adjusting means to adjust the rod lens array in a direction where the rod lens array is separated/closed from/to a linear image sensor, in three spots in the longitudinal direction of the rod lens array at least. CONSTITUTION:A rod lens array 25 is provided as a image formation optical system in the lower direction of a reading position P on an original D. For the array 25, refraction factor distribution type rod lenses, whose refraction factor is gradually and continuously decreased from a center to a circumferential edge, are arranged so that an optical axis can be parallel in a vertical direction. Then, an unmagnified normal image is formed in the symmetrical position of a focusing point to a midpoint in the longitudinal direction. Supporting members 26 are provided on the three spots to include both edges of the array 25. Since an eccentric circular cam 28 is engaged to this member 26, the cam 28 is turned and the member 26 can be respectively adjusted in the vertical direction. Then, the vertical position of both edge parts and central part of the array 25 can be independently adjusted. Accordingly, the deflection of the array 25 can be corrected and resolution can be uniformly adjusted over the whole width of reading original.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a contact type image sensor having a linear image sensor and a rod lens array.

(Prior Art) Generally, in devices that read and input image information, such as facsimiles, image scanners, and digital copying machines, light from an illumination light source is irradiated onto a document, the reflected light is guided to a linear image sensor, and a photoelectric Conversion is being done. Some of the above-mentioned methods have a structure in which a reflected light image of a document is reduced and formed on a light receiving element of an IC type, for example, a COD image sensor using a spherical lens. In addition, the document is illuminated with a solid-state light source such as an LED array, and a reflected light image is generated on the light receiving element of a linear image sensor arranged in the same length as the width of the document using a 1-magnification imaging optical system such as a rod lens array. There is also a method of forming an image at a ratio of 1:1 and performing reading scanning. This latter method is called a contact image sensor, and is gradually being used because it improves the long optical path length caused by the lens optical system of the former and allows the device to be made more compact.

As such a contact type image sensor, for example, the one shown in FIG. 3 is known.

This factor indicates its cross-sectional structure, and the reference numeral 11
indicates a frame. An LED array 12 is arranged on this frame 11. This LED array 12 is formed to be slightly longer than the document reading width, and has a width of approximately 45 mm.
A rod lens array 13 as a coupling optical system is provided on the frame 11 below the document reading position P. The lens array 13 is formed into a rod shape in the width direction of the document, and is made up of a large number of rod lenses arranged in one or two rows so that their optical axes are vertical and parallel.Rod lens array 13 A linear image sensor 14 is fixed to the frame 11 and arranged below the frame 11 .

Then, the irradiated light from the LED array 12 travels in the direction of the arrow shown in the figure, and after being reflected at the reading position P of the document, the rod lens array 13 forms an image on the light receiving element of the linear image sensor 14. ing.

In such a contact type image sensor, a rod lens array support and adjustment mechanism as shown in FIG. 4 is used in order to improve the resolution during reading. That is, on both sides of the rod lens array 13, there are side frames 15.
15 are provided, and these side frames 15.1
5 is provided with a support part 16.16 which projects inwardly.

These supports 16.16 have helical compression springs 17.1
7 are provided, and both ends of the rod lens array 13 are placed on these compression coil springs 17 and 17. on the other hand,
Support body 1 provided inside the side frame 15°15
A set screw 19.19 is screwed into 8.18,
The setscrews 19, 19 are disposed with their lower ends in contact with the upper surfaces of both ends of the rod lens array 13.

In such a support structure, when the set screw] 9 is rotated, the rod lens array 13 moves up and down against the pressing force of the compression coil spring 17. In this way, the rod lens array 13 is positioned at the midpoint between the document tray and the light receiving element of the linear image sensor 14, and adjusted to obtain the best resolution.

(Problems to be Solved by the Invention) Generally, the long rod lens array 13 is
Due to manufacturing errors, it is often slightly bent in the vertical direction in FIG. On the other hand, in the above contact type image sensor, only both ends of the rod lens array are held in an adjustable manner. Therefore, the vertical position of the rod lens array cannot be adjusted over the entire length of the document, that is, the entire width of the document, and the best resolution cannot be obtained over the entire width of the document.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a contact image sensor that can obtain optimal resolution over the entire width of a document.

[Structure of the invention]

(Means for Solving the Problems) The present invention has been made to solve the above problems, and includes a linear image sensor and a rod lens array arranged parallel to the linear image sensor. In the linear image sensor, adjusting means for adjusting the position of the rod lens array in a direction toward and away from the linear image sensor is provided at at least three locations in the longitudinal direction of the rod lens array.

(Function) In the present invention, adjustment means for adjusting the rod lens array in the direction toward and away from the linear image sensor are provided at at least three locations in the longitudinal direction of the rod lens array. Therefore, the resolution can be uniformly and optimally adjusted over the entire width of the document to be read.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of a contact type image sensor according to the present invention, and reference numeral 21 in the figure indicates a frame. The upper surface of this frame 21 is used as a document sliding surface 22, and a window portion 23 is provided in the center thereof. This window part 23
An LED array 24 is provided diagonally below. This LED array 24 has a rod lens for condensing light on its upper part, and is formed to be slightly longer than the width of the original so that the effective illumination length is approximately equal to the width of the original. Then, the reading position P of the document is irradiated linearly.

Further, the LED array 24 is attached to the frame 21 at an angle of approximately 45@ to illuminate the document obliquely.

A rod lens array 25 as an imaging optical system is provided below the document reading position P.

This rod lens array 25 consists of rod lenses of a refractive index distribution type in which the refractive index continuously decreases from the center to the periphery, and are arranged so that their tip axes are parallel to each other in the vertical direction.
A large number of lenses are arranged in a row or two rows, and a life-size statue is focused at a focal point symmetrical to the midpoint in the length direction. This rod lens array 25 is held by support members 26 at its side edge portions, excluding the front axis.

As shown in FIG. 2, the support members 26 are provided at three locations at both ends and the center of the rod lens array 25, and are attached to the side surface of the frame 21. This support member 26 is provided with an oblong hole 27 that serves as a cam follower. A disk-shaped eccentric cam 28 is fitted into this oval hole 27, and a male threaded portion 29 is fitted into this eccentric cam 28.
is provided. The center of the eccentric cam 28 is eccentric with respect to the axis of the male threaded portion 29. The male threaded portion 29 is screwed into the side wall portion of the frame 21, and has a slot 30 formed in its head.

By engaging a driver or the like with the slot and rotating the eccentric cam 28, the support member can be adjusted in the vertical direction.

A linear image sensor 31 is fixedly provided to the frame 21 below the rod lens array 25 . This linear image sensor 31 has a width of 1 which is approximately equal to the width of the document.
:1 to read the image information on the document, the light receiving element array 3
It has 2.

In this way, in the above embodiment, the support members 26 are provided at three locations including both ends of the rod lens array 25, and the eccentric cam 28 is engaged with the support members 26.
By rotating the eccentric cam 28, the support member 26 can be adjusted individually in the vertical direction, and the vertical positions of both ends and the center of the rod lens array 25 can be adjusted independently. Therefore, the rod lens array 25
The deflection of the image can be corrected, and the resolution can be uniformly and optimally adjusted over the entire width of the document to be read.

〔Effect of the invention〕

As described above, according to the present invention, the deflection of the rod lens array can be corrected, and therefore the resolution can be uniformly and optimally adjusted over the entire width of the document to be read.

1 is a cross-sectional view thereof, FIG. 2 is a front view showing vertical adjustment means for a rod lens array, and FIGS. 3 and 4 are views showing a conventional contact type image sensor. FIG. 3 is a sectional view thereof, and FIG. 4 is a front view showing the means for adjusting the rod lens array in the vertical direction.

・25...Rod lens array, 28...Eccentric cam, 31...Linear image sensor.

Claims (1)

[Claims] A contact type image sensor comprising a linear image sensor and a rod lens array disposed parallel to the linear image sensor between the linear image sensor and the document surface, at least three positions in the longitudinal direction of the rod lens array. A contact type image sensor, further comprising an adjusting means for adjusting the position of the rod lens array in a direction toward and away from the linear image sensor.