JPS5843656A - Light source for original sheet reader - Google Patents

Abstract

PURPOSE:To increase a binary-coded margin against a red original, and to improve quality, by simultaneously turning on and using 2 light emission diode arrays of green and yellow. CONSTITUTION:In original sheet reader light sources 10, 11 placed in 2 rows by placing a photoconductive system 8 between them, of an original sheet reader constituted by providing a light source, the photoconductive system and a photodetector array 9, one row of the light sources consists of a green light emission diode array 10, and the other row consist of a yellow light emission diode array 11. A binary-coded margin can be increased by adjusting an input current so as to make intensity of illumination from both the light sources 10, 11 the same, turning them on simultaneously, and illuminating an original.

Description

[Detailed description of the invention] The present invention relates to an improvement in a light source for a contact type N-reader.

The conventional contact type N-reader (Ijll
tl: Read with the size of 1 @) #il1 A brief explanation of the 0 diagram that has the structure shown in Figure 1 is where 1 and r are light sources, and 2 is a light guide using, for example, a 7-luffo or cleansing device. 3 is a light receiving element array, and 4 is an electric circuit. Then, the original 6, which is fed by the roller 6, is sent to the light source 1. The reflected light is guided to the light-receiving element array 3 by the light guide system 2, where it is photoelectrically converted and the original is read.

It has become.

In this way, the inventors proposed to use a yellow emitting diode array with a center wavelength of 560 to 580 nta as a light source in a document reading device for the purpose of simplifying the configuration, lowering the price, and reducing power consumption. .

The second one is the wavelength of 555am, which has high brightness currently on the market.
Green light emitting diode and wavelength 5701! This shows the dependence of luminous intensity on the input current of a 11O yellow light-emitting diode.The yellow light source (indicated by the curved line) is more than 5 times as bright as the green light source (indicated by -! mB). ,
Also, if the brightness is the same, a yellow light source is approximately 175 times brighter than a green light source.
It is possible to reduce the input current of this power consumption. When the reflected light from a white document is received by the light-receiving element, the bright resistance changes as shown in 3wJ, and the yellow light source (indicated by the hammer) is better than the green light source (indicated by the arrow). ,−
The resistance is lower than that shown by B). Yellow light sources like jin are excellent as light sources, but they also have the following drawbacks:
That is, as shown in Figure 114, the contrast of the original manuscript/red manuscript is smaller for the yellow light source (indicated by the curve B) than for the green light source (indicated by the curve B), and the limit contrast F level (chain @C
) is close to K, so the binary I/O margin is narrow. This narrow binarization margin is caused by the surrounding conditions (
(Most of the temperature) is strange? When the i-characteristics of the light-receiving element changes or the amount of light changes, there is a risk that binarization will not be possible.The present invention was devised to solve this problem. be.

ζ In the present invention, the light guide system of the document reader is configured to include a light source, a light guide system, and a light receiving element. , light source t
) One row uses a green dim light emitting diode array, and the other row uses a monochromatic emitting diode array.

'T'''+'@''iK*-bhr, square,,a''101!
jltllK) *Explain in detail.

FIG. 8 shows a configuration diagram of a document reading device using the light source of the embodiment.

10 and 11 are light sources of the present invention. The light sources 1G and ll#i self-occurring lenses r8t- are arranged in a 2^ arrangement, with the light source 10 in one row having a light center wavelength of 5.
A 55 mm green light emitting buoy array was used, and the light source 11 in the other row had I/'i emission with a center wavelength of 570 nt.
It is a good product using a yellow light emitting diode array of m.

In this embodiment configured as described above, the input current to each light source is adjusted so that the illuminance from both light sources 1G and 11 is the same, and the degree of illumination from the green light source 11 is slightly decreased. They light up simultaneously to illuminate the original. Note that when the green light source and the yellow light source have the same brightness, the input current has a relationship as shown in No. 6-. In this way, when both light sources are set to the same luminance, the contrast dependence for red originals and black originals is as shown in 11 and 2 in 711. For the limit contra trepel shown by the dashed line 0;
becomes large. Note that the plot line in the figure is the case when the green light source is used alone, and the curve B is when the yellow light source is used alone. From my point of view, if you use both green and yellow light sources and look at the large case (track 1!D) from the green light source (-tsum), the decrease in contrast is sufficiently larger than the limit of the average, so the decrease is not a problem. This results in a more stable operation. On the other hand, compared to the yellow light source (11111B), the power consumption is large (although it is possible to significantly improve the contrast and expand the margin of the Kuni value level to 1), making it easier to consider evening temperature fluctuations. , the question is whether there is a difference in the optimal distance between the original light-receiving elements in the light guiding system when two yellow lights are used for tttt.
It becomes a problem. 8th m! Is 1 a 4-'e line to the light source? (Spatial frequency characteristics) This shows the dependence of the OIIA product on the distance between light-receiving elements. This is the case when using the SELFOC lens of 4A, and the middle curve 4a is a green light source with a center wavelength of 555.1 curve B is a yellow light source with a center wavelength of 57G.-C is 1ffF when both light sources are turned on. The required condition for M'tr over 6 tatami, which shows dependence, is 50 hiss or more, but in any case, at 60%, the distance between the original photodetector and the original light receiving element is ±ls.
It can be seen that there is no problem in the case of the present invention since the width is larger than ag.

As explained above, in the light source for an original reading device of the present invention, it is possible to increase the binarization margin for red originals by using two light emitting diode arrays of green and yellow that are lit simultaneously. This greatly contributes to improving the quality of monograph reading 11L#I&.

[Brief explanation of the drawing]

Number 1- is a cross-sectional view of an example of a conventional calligraphy-type original handling device, and number ** is the dependence of the luminous intensity on the input current of the green and yellow luminescent images! 1. Showing the nine figures, 3. Showing the difference in light resistance of the light receiving element when changing the light source in the company's original manuscript.
Figures 1 and 4 are autograph manuscripts. For a red original: 2 y ) (D light) shows the dependence of the input voltage when changing the light source.
No. 61I shows the difference in the input current of the green and yellow light diode arrays for the same *t, ortholuminescence light emission, 9-1,
No. 781 is a diagram showing differences in contrast with respect to various light source input currents, and a diagram showing the dependence of W' on the distance between the s-th fused Fi manuscript light-receiving elements. 7...Original, 8... Light guide system, 9... Light receiving element array, lO... Green light emitting ion array, 11...
Yellow light emitting diode array. Patent Applicant: Fujitsu Limited, Patent Attorney: Patent Attorneys: Aoki and Akira, Patent Attorneys: Kazuyuki Nishidate, Patent Attorneys: 1) Kushio Patent Attorney: Akira Yamaguchi, Input Current (mA) Figure 3 Figure 4 Figure 6 yA Green array Input current (A)

Claims (1)

[Claims] 1. In a light source for a good document integration device arranged in two rows with the light guide system in between, in a document reading device configured with a light source, a light guide system, and a light receiving element, one row of light sources #: t #A light source for a document reading device that uses a color light emitting diode array and the other row uses a yellow light emitting diode array.