JPH0533268U - Optical character reader - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] Two dropout colors can be used with one fluorescent lamp. [Structure] The form 8 is illuminated with a red fluorescent lamp 3. On the form 8, pencil characters are described in a character frame displayed with red and blue as dropout colors. The optical filter 1 has a transmission characteristic in which the emission wavelength band of the red paint of the fluorescent lamp 3 is a transmission band, and the optical filter 2 has a transmission characteristic in which the emission wavelength band of the mercury gas enclosed in the fluorescent lamp 3 is a transmission band. The signal input to the optical image processing unit 7 through the optical lens 5 in which the optical filter 1 and the fluorescent lamp 3 are combined and the photoelectric conversion element 6 has a significantly small pencil character level when the character frame is red. The slice level is set so that only the level of the pencil character is extracted, and the character frame is binarized so that the character frame becomes the white level and the pencil character becomes the black level. By combining the optical filter 2 and the fluorescent lamp 3, the blue character frame is dropped out, and one fluorescent lamp can use two dropout colors.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical character reader, and in particular, an original document surface (hereinafter, simply referred to as a “form”) surface is illuminated by a fluorescent lamp and an optical image of the form surface is formed on a photoelectric conversion element to form an image on the form surface. The present invention relates to an optical character reader that recognizes by inputting and extracting only character images from this input.

[0002]

[Prior Art]

 Conventionally, in this type of optical character reading device, a character frame for writing characters on a form has been printed as a guide for specifying the character writing position.

These character frames are necessary as a guide for writing characters, but are unnecessary for character recognition.

When the image of the character frame itself appears in the character image, the character recognition is adversely affected.

Therefore, when the document surface is illuminated by the fluorescent lamp, it is necessary to drop out these character frames so that they cannot be distinguished from the white background of the document. For this reason, the print color of these character frames is generally the same as the color of the light source that illuminates the form, and these print colors are called dropout colors.

The dropout color is also used for color coding of forms when there are various forms, and it is desirable for the optical character reader to be able to drop out various types of dropout colors.

In addition, as a light source of an optical character reading device of this type, a fluorescent lamp of monochromatic light such as red or yellow-green is generally used as a light source in order to obtain small size, low power consumption and high illuminance.

[0008]

[Problems to be solved by the device]

 However, when using the above-mentioned single-color fluorescent lamps as a light source, for each single-color fluorescent lamp, when using a dropout color of the same color as the fluorescent lamp, for example, a red fluorescent lamp, only the red-based dropout color is dropped out. There is a problem that you cannot do it.

Therefore, in order to drop out two or more dropout colors such as red and blue, it is necessary to use a plurality of these monochromatic fluorescent lamps and sequentially switch the lamps according to the form color. There is an annoyance.

Further, since a plurality of types of fluorescent lamps are used, the mounting space for these fluorescent lamps becomes large and it is difficult to downsize the device.

An object of the present invention is to solve the above-mentioned problems and to provide an optical character reader capable of using a plurality of dropout colors with one fluorescent lamp.

[0012]

[Means for Solving the Problems]

 The device of the present invention is an optical character reading device for illuminating a document by a fluorescent lamp and forming an optical image of the document surface on a photoelectric conversion element to obtain a character image described in a character frame on the document surface. , A fluorescent lamp that illuminates the original surface, a first optical filter that transmits only the light source in the wavelength band emitted by fluorescent paint among the light rays emitted from this fluorescent lamp, and the light rays emitted from the fluorescent lamp The second optical filter that transmits only the light in the wavelength band emitted by the enclosed gas in the tube and either the first or the second optical filter are kept at a position that limits the incident light of the photoelectric conversion element. It has a filter switching unit that it has, and an optical image processing unit that eliminates the output of the character frame from the optical image obtained through the first or second optical filter.

In addition, the device of the present invention is a binarized slice level for discriminating between the characters described in the character frame and the character frame with respect to the light output output through the first or second optical filter. Is set, and the described character is set to the black level and the character frame is set to the white level, and the binarization is performed to eliminate the output of the character frame represented by the white level.

[0014]

【Example】

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

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention.

In this embodiment, a fluorescent lamp 3 for irradiating a form surface, an optical filter 1 as a first optical filter, an optical filter 2 as a second optical filter, an optical filter 1 and an optical filter 2 are used. The filter switching unit 4, which holds any one of them in a position to limit the incident light of the photoelectric conversion element, the optical lens 5, the photoelectric conversion element 6, and the optical image obtained through the optical filter 1 or the optical filter 2, It is provided with an optical image processing unit 7 for eliminating the output of the character frame, and the form 8 is also shown in FIG.

Next, the operation of this embodiment will be described.

The optical filter 1 has a transmission characteristic of transmitting a light ray having a long wavelength of 600 nm or more as shown by a transmission characteristic 23 of the optical filter 1 shown in FIG. 2B. On the other hand, the optical filter 2 has a characteristic of transmitting a light ray having a short wavelength of 600 nm or less, as shown by the transmission characteristic 24 of the optical filter 2 shown in FIG.

The fluorescent lamp 3 is a red fluorescent lamp having the emission intensity characteristic shown in FIG. As shown in the emission wavelength characteristic 21 of the red fluorescent paint, the light ray of the fluorescent lamp 3 is the light ray component emitted by the red fluorescent paint, and the light ray of the mercury gas itself inside the tube shown in the emission wavelength characteristic 22 of the mercury gas. Composed of ingredients.

The optical filters 1 and 2 are attached to the filter switching unit 4, and either the optical filter 1 or 2 can be placed on the optical path by moving the lever in the direction of the arrow.

The optical lens 5 and the photoelectric conversion element 6 have the same functions as those in a normal optical character reading device, and the fluorescent lamp 3 illuminates the visual field of the photoelectric conversion element 6 on the form 8. The optical lens 5 forms an optical image of the field of view of the photoelectric conversion element 6 on the light receiving surface of the photoelectric conversion element 6.

Now, it is assumed that the form 8 has a character frame 32 printed in red and a character 33 written with a pencil, as shown in FIG. 3A.

First, the content of the red character frame 32 being dropped out will be described.

In FIG. 1, the lever is moved to position the optical filter 1 on the optical path, and the fluorescent lamp 3 is turned on.

Since the optical filter 1 has the transmission characteristic shown by the transmission characteristic 23 of the optical filter 1 in FIG. 2B, the light ray incident on the photoelectric conversion element 6 is the component shown in FIG. Then, it is only the component shown by the emission wavelength characteristic 21 by the red fluorescent paint. Therefore, the video signal obtained from the photoelectric conversion element 6 is determined by the size of the light rays in the combined wavelength band 29 of the fluorescent lamp 3 and the optical filter 1 in FIG.

In general, the reflectance of black with a pencil is very small regardless of the wavelength, and is incident on the photoelectric conversion element 6, as shown in the reflectance characteristic 28 of the pencil of FIG. 2C. There are few rays. Therefore, when looking at the combined band 29 of the fluorescent lamp 3 and the optical filter 1 in FIG. 2 (c), the pencil character portion is significantly smaller than the reflectance 25 of the white background of the form. Even in the video signal obtained from the photoelectric conversion element 6, the signal is remarkably reduced as compared with the white background of the form. The pencil character part level 35 in FIG. 3B shows this state.

On the other hand, the reflectance of the red ink in the character frame 32 generally shows a characteristic as shown in the reflection characteristic 26 of the red ink in FIG. The reflectance is large at wavelengths of 600 nm or more, but in the combined wavelength band 29 of the optical filter of the optical lamp 3, the difference between the reflectance of the white background and the reflectance of the red character frame portion of the form 8 is very small. Therefore, the difference between the two is very small even for the light beam incident on the photoelectric conversion element 6, and the same is true for the video signal of the photoelectric conversion element 6. This state is shown in FIG. 3B as a red character frame portion level when the fluorescent lamp 3 and the optical filter 1 are used and a blue character frame portion 34 when the fluorescent lamp 3 and the optical filter 2 are used.

In the optical character reader, a slice level is set for the video signal obtained as described above to obtain a binary image. In FIG. 1, this processing is expressed as being performed by the optical image processing unit 7.

The slice level may be set so that the image of the character frame disappears and a binary image of an appropriate pencil character is obtained. For example, the binarized slides shown in (b) and (c) of FIG. Level 37 is set.

If the signal level is lower than the binarized slice level 37, it is black, and if it is high, it is white. In the case of FIG. 3B, since the pencil character part level 35 is lower than the binarized slice level 37, it is all black, and the character frame 32 part is higher than the slice level. It becomes white. As a result, the red character box part is dropped out.

Next, consider the case where the character frame 32 in FIG. 3A is blue.

When the character frame 32 is blue, if the combination wavelength band 29 of the fluorescent lamp 3 and the optical filter 1 shown in FIG. 2C is used, the white background of the form indicated by the reflection characteristic 25 of the white background of the form is displayed. Since the reflectance of the blue ink, which is represented by the reflection characteristic 27 of the blue ink, is significantly lower than that of the reflectance, the video signal of the photoelectric conversion element 6 is a blue signal when the fluorescent lamp and the optical filter 1 of FIG. As shown in the character box level 36, the level of the character box part is lowered, and it becomes indistinguishable from the written characters of the pencil, and the character box cannot be dropped out.

Therefore, the filter switching unit 4 in FIG. 1 is switched to place the optical filter 2 on the optical path.

As shown by the transmission characteristic 24 of the optical filter 2 in FIG. 2B, the optical filter 2 has the emission wavelength characteristic 22 of the mercury gas shown in FIG. Since only the light rays shown can be transmitted, the light rays incident on the photoelectric conversion element 6 are only the combined wavelength band of the fluorescent lamp 3 and the optical filter 2 in FIG. Therefore, it is only this band that affects the video signal of the photoelectric conversion element 6.

Even in this band, the reflectance of the pencil character portion indicated by the reflection characteristic 28 of the pencil is significantly different from the reflectance of the white background of the form 8 indicated by the reflection characteristic 25 of the white background of the form, and thus (b) of FIG. Alternatively, the level is the same as the pencil character part level 35 shown in (c).

On the other hand, since the reflection characteristic of the blue ink in the character frame portion with respect to the wavelength is as shown by the reflection characteristic 27 of the blue ink in FIG. 2C, the combination wavelength band of the fluorescent lamp 3 and the optical filter 2 is shown. Comparing No. 30 with the reflection characteristic 25 on the white background of the form, the difference between both is small. Therefore, the waveform of the video signal obtained from the photoelectric conversion element 6 becomes as shown in FIG. 3B, and the level of the portion of the blue character frame 32 increases. Therefore, when the binarization is performed by the binarization slice level 37, the image of the portion of the blue character frame 32 is dropped out.

By switching the optical filters 1 and 2 as described above, it is possible to drop out any of the red and blue character frames.

[0038]

[Effect of the device]

 As described above, the present invention provides one of two optical filters having a transmission band of the emission wavelength of the fluorescent paint and the emission wavelength of the enclosed gas of the fluorescent lamp that illuminates the form surface in which the characters are written in the character frame. By combining with a fluorescent lamp, the light is received so that the character frame level is larger than the written characters, and the binarized slice level is set in the photoelectric conversion output to extract only the written characters as a black level. The dropout color of the character frame can use not only the emission color of fluorescent paint but also the emission color of the enclosed gas. Only one fluorescent lamp is required for the use of two dropout colors. This has the effect of ensuring downsizing and reduction in maintenance man-hours for fluorescent lamps.

[Brief description of drawings]

FIG. 1 is a perspective view showing a partial block of an embodiment of the present invention.

FIG. 2 is a diagram showing an emission intensity characteristic (a) of a fluorescent lamp, a transmission characteristic (b) of an optical filter, and a reflection characteristic (c) of each part of a form with respect to an incident light wavelength in one embodiment of the present invention.

FIG. 3 shows a layout (a) of a form, a first example (b) and a second example (c) of a character frame level of a photoelectric conversion element output by a combination of a fluorescent lamp and an optical filter in one embodiment of the present invention. It is a figure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical filter 2 Optical filter 3 Fluorescent lamp 4 Filter switching unit 5 Optical lens 6 Photoelectric conversion element 7 Optical image processing unit 8 Form 21 Emission wavelength characteristic of red fluorescent paint 22 Emission wavelength characteristic of mercury gas 23 Transmission characteristic of optical filter 1 24 Transmission characteristics of the optical filter 25 Reflection characteristics of white paper on the form 26 Reflection characteristics of red ink 27 Reflection characteristics of blue ink 28 Reflection characteristics of pencil 29 Combination wavelength band of fluorescent lamp 3 and optical filter 30 Fluorescent lamp 3 and optical filter 2 Combination wavelength band 31 Field of view of photoelectric conversion element 32 Character frame 33 Pencil character 34 Red character frame part level when fluorescent lamp 3 and optical filter 1 are used and blue character frame part level when fluorescent lamp 3 and optical filter 2 are used 35 Pencil character Frame level 36 Blue character frame when fluorescent lamp 3 and optical filter 1 are used Min level 37 binarization slice level

Continued Front Page (72) Inventor Yoshiro Neo 1-1, Shinurashima-cho, Kanagawa-ku, Yokohama-shi, Kanagawa 25 NEC Electric Robot Engineering Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. An optical character reading apparatus for illuminating a document by a fluorescent lamp and forming an optical image of the document surface on a photoelectric conversion element to obtain a character image described in a character frame of the document surface. A fluorescent lamp for illuminating the light source, and a first optical filter for transmitting only a light source in a wavelength band of light emitted from the fluorescent lamp by the fluorescent paint,
A second optical filter that transmits only a light beam in a wavelength band emitted by the sealed gas in the tube among the light beams generated from the fluorescent lamp, and one of the first and second optical filters is incident on the photoelectric conversion element. It is characterized by comprising a filter switching unit for holding the light at a position for limiting the light and an optical image processing unit for eliminating the output of the character frame from the optical image obtained through the first or second optical filter. Optical character reader. 2. A binarized slice level for discriminating a character described in the character frame from the character frame is set with respect to a light reception output that has passed through the first or second optical filter,
The optical character reading device according to claim 1, wherein binarization is performed in which the written character is set to a black level and the character frame is set to a white level, and the output of the character frame represented by the white level is eliminated.