JPH02121562A - Close-contact type image sensor - Google Patents

Abstract

PURPOSE:To read out only the character symbols of desired colors by performing the switch between the LEDs having different peak light emission wavelengths. CONSTITUTION:A lens array 2 contains many refractive index distribution type fiber lenses and forms an erecting lifesize image of a reading form 5 on the photoelectric conversion surface of a 1-dimensional image sensor 1. Then the image formed on the photoelectric conversion surface is converted into the electric signals by the sensor 1. A red LED array 4 has its peak wavelength approximate to 660nm and serves as a red light source to reflect satisfactorily the reddish colors. In other words, a red color is defined as a drop-out color. In such a way, two LEDs having different peak light emission wavelengths are switched with each other. That is, the yellow and green colors are dropped out and the print of a red color is read when a yellow/green LED array 3 is turned on. Then the print of a red color is dropped out when the array 4 is turned on. For instance, it is possible to read the red seal impressions, etc., while dropping out the red character entry frames via an optical character reader.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device, and particularly to a contact type image sensor in which spectral sensitivity characteristics can be selected.

[Conventional technology]

Conventionally, this type of image reading device has used a filter to change the spectral sensitivity characteristics.

[Problem to be solved by the invention]

In the case of the conventional method of changing spectral sensitivity characteristics using filters described above, in the case of a close-contact type, the sensor is large, so it is difficult to install a plurality of filters that cover the entire surface in a limited space. In addition, there are so-called color sensors that have filters attached to each different photocell and change the spectral sensitivity characteristics through electrical scanning.

The drawback is that the main drive circuit is expensive and complex.

[Issues to solve problems]

The contact image sensor of the present invention has a function of switching light sources with different emission wavelengths and changing the overall spectral sensitivity characteristics without using a filter.

That is, according to the present invention, a lens array is provided relatively close to the reading paper, a one-dimensional image sensor is arranged in parallel above the lens array, and a light source is placed on the side of the lens array. In the contact image sensor, the light source is configured by arranging a plurality of LED arrays with different output wavelength characteristics in parallel, and these L
By switching the ED array, the overall spectral sensitivity characteristic can be changed and a dropout color can be selected.A contact type image sensor is obtained.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows that the overall spectral sensitivity characteristics according to the embodiment of the present invention are 2.
FIG. 2 is a schematic perspective view of a contact type image sensor from which types can be selected. In FIG. 1, a lens array 2 is a lens array formed by arranging a large number of gradient index fiber lenses.
Connect to the photoelectric conversion surface. The image connected to the photoelectric conversion surface is converted into an electrical signal by the one-dimensional image sensor 1.

The red LED array 4 is an array of LEDs having a peak wavelength around 660 nm and provides a red light source.

Red colors reflect well. In other words, red is the dropout color.

The yellow-green LED array 3 is an array of LEDs with a peak wavelength around 570 nm, and provides yellow-green light TTi, and yellow-green colors are well reflected. Namely.

All dropout colors will be yellow-green.

As explained above, by switching between LED-i with two different peak emission wavelengths, when the yellow-green LED array is turned on, the yellow-green color is missed.

Read the red print. Also, when all red LED arrays are lit, red printing will be missed. For example, as an optical character reading device, it is possible to read the whole red stamp etc. while overlooking the written red characters.

In the above description, two types of LED arrays are used, but three or more types may be arranged symmetrically or close to it. However, in reality, if there are more than 5 types, LED
Since a part of the array is separated from the reading paper 5, its sensitivity is reduced.

〔Effect of the invention〕

As explained below, the present invention makes it possible to read out only characters and symbols of a desired color by using a plurality of LEDs having different peak emission wavelengths.

Figure 1 Beam 7c1 Meji Niza

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of the invention. Explanation of symbols 21...-dimensional image sensor, 2...
Lens array, 3... Yellow-green LED array, 4...
Red LED array, 5...reading paper.

Claims (1)

[Claims] 1. A lens array is provided relatively close to the reading paper, a one-dimensional image sensor is arranged parallel to the top of this lens array, and a light source is placed on the side of the lens array. In a close-contact image sensor that irradiates the reading paper directly below the array, the light source includes a plurality of LEs having different output wavelength characteristics.
A light source configured by arranging D arrays in parallel with each other,
This contact type image sensor is characterized in that by switching these LED arrays, the overall spectral sensitivity characteristics can be changed and a dropout color can be selected.