Picture reading apparatus

Abstract

In an image sensor which has a photoelectric conversion element group, an illumination device having light sources of at least three emission colors R, G, and B, an imaging lens, and the like, moire noise in a color output image is eliminated, the original reading time is shortened, and a cost reduction is attained. For this purpose, a sensor array including a linear array of a plurality of photoelectric conversion elements, a lens array for imaging an original image on the sensor array, an illumination device using LEDs having emission colors R, G, and B, and a cover glass are supported by and fixed to a frame. The conjugate length of the lens array is set to fall within the range between the R and G emission wavelengths. An original pressed against the cover glass is illuminated by the illumination device, and light reflected by the original is converted into electrical signals by the sensor array, thereby reading the original image.

Description

[0001] This application is a divisional application of the application titled "Image Reading Device and Image Reading System", the filing date is August 1, 1997, and the application number is 97115314.0. technical field [0002] The present invention relates to an image reading device for reading an image of a color original in particular and an image reading system using the image reading device. Background technique [0003] Figure 13 is a cross-sectional view showing an example of an image sensor. The sensor comprises a sensor array 1 made by mounting sensor ICs 101 on a sensor board 102, a lens group 2, an LED array 6 with three different LEDs 301, 302 and 303 serving as a reference to the original The light source for the illumination, the cover glass 4, and the frame 5, are used to hold these elements in place. The LED array 6 is constructed by mounting a plurality of different types of LED elements 301, 302, and 303 on one board, for example, 20 or more elements are...

AI Technical Summary

Problems solved by technology

[0008] However, since the above-mentioned conventional image sensor uses a lens group with a small aperture angle, the light transmission efficiency is low, and the reading speed of the original is limited.

[0009] In addition, in a lens group with a small aperture angle, the distance from the original surface to the sensor is large, so that the size of the image sensor using this lens group becomes large

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