JP2546319Y2 - Optical character reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to an optical character reader, in particular, irradiates a document as a document with a light source such as a fluorescent lamp, and photoelectrically converts light / dark information based on characters on the document. The present invention relates to an optical character reader for obtaining a video signal.

[Conventional technology]

On a form to be read by an optical character reading device (hereinafter abbreviated as OCR), a character frame and the like as a guide of a character size and an entry position are printed. These printing colors are called dropout colors and are irrelevant to the original reading of the OCR, so it is desirable that these dropout colors do not appear on the video signal obtained from the image sensor. For this reason, a fluorescent lamp having the same emission color as the dropout color is used. However, when the dropout color is diversified, a fluorescent lamp having a different emission color is switched and used.

Conventionally, in an optical system of this type of device, light sources having different emission colors face each other as shown in FIG.

FIG. 9 is a perspective view showing a first example of a conventional OCR.
FIG. 9 shows an example in which a form is optically read using a CCD image sensor by line scanning, and a common visual field is used for a green fluorescent lamp 3 and a near-infrared fluorescent lamp 4 as light sources of different wavelength bands. (Irradiation field) Irradiate 6 and optical lens 20
The optical image formed by is photoelectrically converted by an image sensor 21 using a CCD to produce a video signal.

[Problems to be solved by the invention]

Conventionally, in this type of OCR, a CCD image sensor or the like is frequently used as a photoelectric conversion element for converting light / dark information on a form into an electric signal.However, in order to improve the reading speed of a document, a CCD image sensor is required. Need to shorten the scanning time. Even if the scanning time of the CCD image sensor is shortened, it is necessary to increase the amount of light incident on the CCD image sensor in order to obtain a video signal output level with a good S / N ratio. That is, it is necessary to irradiate the original with a high-luminance light source.

However, when the above-described fluorescent lamp is used as a light source, it consumes less power, but it is difficult at present to obtain a sufficient luminance compared with an incandescent lamp such as a halogen lamp.

In order to increase the brightness, it is conceivable to mount a plurality of fluorescent lamps of the same color, but the device becomes large-scale.

For this reason, conventionally, as shown in FIG. 10, the reflectors 13a and 13b are positioned close to the form 5 and not blocking the visual field 6.
The method of providing is taken. According to this method, the reflected light from the paper surface and the direct light from the fluorescent lamp are reflected toward the original by the reflectors 13a and 13b, and are used for illumination to increase the illuminance of the field of view 6.

However, in this method, if the width of the reflectors 13a and 13b is increased to increase the reflection effect, the illumination light from the two fluorescent lamps to the document surface is blocked, so that the width of the reflectors is limited. However, there is a problem that a sufficient reflection effect cannot be expected.

[Means for solving the problem]

The optical character reading device according to the present invention includes a pair of two light sources that are adjacently arranged in parallel and emit light of different wavelength bands to irradiate a common irradiation area of a document to be optically read; A pair of two light sources disposed between the respective light sources of the light sources and the irradiation region, transmitting light beams in the wavelength band of the corresponding light source and reflecting light beams in the wavelength band of the light source that do not correspond to the respective light sources. Comprising an optical filter, reflected by the optical filter corresponding to the other light source, the reflected light from the irradiation region by the light of one of the light sources that irradiate the irradiation region, the irradiation region again by the reflected light Irradiating, and reflecting light reflected from the irradiation area by the light beam of the other light source irradiating the irradiation area by the optical filter corresponding to the one light ray, So that again irradiating the irradiation region by light.

〔Example〕

Next, the present invention will be described with reference to the drawings. First
FIG. 2 is a perspective view showing the configuration of the first embodiment of the present invention. The embodiment shown in FIG. 1 comprises optical filters 1 and 2, a green fluorescent lamp 3, a near-infrared fluorescent lamp 4, an optical lens 20 and an image sensor 21, and FIG. And the field of view 6 formed on the form 5 are also shown.

The green fluorescent lamp 3 and the near-infrared fluorescent lamp 4 are
And illuminates the field of view 6 from a target position with respect to the field of view 6. The optical filter 1 is disposed at a position where the illumination light from the green fluorescent lamp 3 to the visual field 6 is blocked, and the optical filter 2 is disposed at a position where the illumination light from the near-infrared fluorescent lamp 4 to the visual field 6 is blocked. ing. FIG. 2 shows the positional relationship between the two fluorescent lamps, the two optical filters, and the document as a document as viewed from the direction of the arrow in FIG.

The optical lens 20 forms an optical image of the illuminated field of view 6 on the original 5 by line scanning on a light receiving surface of an image sensor 21 using a CCD.

FIG. 3 shows an example of the emission wavelength band of each fluorescent lamp.
Here, the green fluorescent lamp 3 emits green light, and the near-infrared fluorescent lamp 4 emits near-infrared light.

An example of the transmission and reflection characteristics of the optical filters 1 and 2 is shown in FIG. Here, the optical filter 1 transmits visible light including green light, and reflects light having a longer wavelength than the near infrared region. In addition, the optical filter 2 transmits light having a wavelength longer than the near-infrared region and reflects visible light.

An example of the optical system when only the green fluorescent lamp 3 is turned on is shown in FIG. Since the emission wavelength of the green fluorescent lamp 3 is in the transmission region of the optical filter 1, the green light 7 emitted from the green fluorescent lamp 3 passes through the optical filter 1 and proves the field of view 6. The reflected light 8 is light reflected by the visual field 6.

On the other hand, the emission wavelength of the green fluorescent lamp 3 is
In the reflection area. For this reason, the reflected light 8 from the paper surface is reflected by the filter 2, and becomes a light beam 9 again proving the visual field 6.

Similarly, when the near-infrared fluorescent lamp is turned on, the reflected light from the paper surface illuminates the field of view 6 again by the optical filter 1.

 As described above, the illuminance of the visual field can be increased.

FIG. 6 is a perspective view showing the configuration of the second embodiment of the present invention. In the second embodiment shown in FIG. 6, a curved surface formed so that the center of the radius of curvature coincides with the center of the field of view 6 instead of the optical filters 1 and 2 of the first embodiment shown in FIG. The difference is that optical filters 1a and 1b are used, and other configurations are the same.

FIG. 7 is a side view of the fluorescent lamp and the optical filter when the embodiment of FIG. 6 is viewed from the direction of the arrow.

The state when the green fluorescent lamp 3 is turned on is shown in FIG. The optical filters 1a and 2a have the same transmission and reflection characteristics as the optical filters 1 and 2. As in the description of FIG. 5, the reflected light from the paper of the form 5 is an optical filter.
Although reflected by 2a and used again as illumination light on the paper surface, since the optical filter 2a has a cylindrical curved surface,
Since the light beams in different directions as shown by the light beams 10 to 12 are reflected and condensed to illuminate the visual field 6, the illuminance of the visual field 6 is increased as compared with the case of FIG. Similarly, when the near-infrared fluorescent lamp 4 is turned on, the amount of light in the visual field 6 increases.

In this manner, by irradiating a common field of view (irradiation field) with light sources of different wavelength bands through an optical filter that transmits only the wavelength band of each light source, the illuminance of the field of view can be significantly increased.

In the above-described embodiment, a fluorescent lamp is used as a light source. However, it is apparent that the present invention can be similarly implemented using another low-luminance light source.

[Effect of the invention]

As described above, the present invention illuminates the field of view of an original to be read in an optical character reader with two light sources having different wavelength bands, and separates only the light in the wavelength band of the corresponding light source between the two light sources and the field of view. An optical filter that transmits light is provided, and the reflected light from the light field of one light source that illuminates the visual field indicating the illumination area is reflected by the optical filter corresponding to the other light source, and the light field is similarly illuminated. The reflected light from the field of view by the light source of the other light source is reflected by the optical filter corresponding to the one light source, and the field of view is again illuminated by the reflected light, so that the illuminance of the field of view can be significantly increased, There is an effect that a video signal output with a sufficiently high S / N ratio can be obtained even if the scanning time of an image sensor using a CCD is reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the configuration of the first embodiment of the present invention, FIG. 2 is a side view of the optical filter and the fluorescent lamp viewed from the direction of the arrow in the embodiment of FIG. 1, and FIG. FIG. 4 shows the emission wavelength characteristics of the fluorescent lamp in the embodiment shown in FIG. 4, FIG. 4 shows the transmission and reflection characteristics of the optical filter in the embodiment shown in FIG. 1, and FIG. 5 shows the operation of the optical filter in the embodiment shown in FIG. ,
FIG. 6 is a perspective view showing the configuration of the second embodiment of the present invention, FIG. 7 is a side view of the optical filter and the fluorescent lamp viewed from the direction of the arrow in the embodiment of FIG. 6, and FIG. 9 is a perspective view showing a first example of a conventional optical character reading device, and FIG. 10 is a perspective view showing a second example of a conventional optical character reading device. is there. 1,2,1a, 2a …… Optical filter, 3… Green fluorescent lamp,
4 ... Near-infrared fluorescent lamp, 5 ... Form, 6 ... Field of view, 7
… Green light, 8… reflected light, 9… ray, 10-12… reflected light, 13a, 13b… reflector, 20… optical lens, 21…
Image sensor.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiro Neo 5-7-15 Shiba, Minato-ku, Tokyo NEC Robot Engineering Co., Ltd. (56) References JP-A-60-146567 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A pair of two light sources which are adjacently arranged in parallel and emit light of different wavelength bands to irradiate a common irradiation area of an original to be optically read, and a pair of two light sources. A pair of two optical filters disposed between each light source and the irradiation area, and transmitting light beams in the corresponding wavelength band of the light source and reflecting light beams in the corresponding wavelength band of the light source. The reflected light from the irradiation area by the light of one of the light sources that irradiates the irradiation area is reflected by the optical filter corresponding to the other light source, and the reflected light is again irradiated on the irradiation area, The reflected light from the irradiation area by the light beam of the other light source irradiating the irradiation area is reflected by the optical filter corresponding to the one light source, and the reflected light again An optical character reading device characterized by irradiating an irradiation area.