JPS6128260B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document reading device that can read calligraphy and drawings of several different colors printed on the surface of a document by color separation.

2. Description of the Related Art Conventional document reading devices such as facsimile and OCR devices have the configuration shown in FIG. In the figure 1
2 is a driving roller for conveying the original 1, 3 is a fluorescent lamp for illuminating the original, 4 is a lens, and 5 is a solid-state imaging device such as a CCD imaging device.

The calligraphic image of the original document 1 is imaged by the lens 4 on the light receiving surface of the solid-state image sensor 5 and photoelectrically converted. In this case, the horizontal reading scan (main scan) of the document surface 1a
This is electronically performed by a shift register built into the solid-state image sensor 5, and the vertical scanning (sub-scanning) of the document surface is performed by the driving roller 2.
This is carried out by conveying it continuously or intermittently in the direction of arrow A. As a result, the original surface 1a is read line by line. The spectral sensitivity characteristics of the photoelectric conversion system are roughly matched to the specific luminous efficiency characteristics of the eye.
Therefore, the level of the photoelectric conversion signal is proportional to the density of the original. By converting this photoelectric conversion signal into a binary signal using a predetermined threshold value, information consisting of characters and images can be read.

Since the conventional document reading device is configured as described above, reading is performed that is related only to the density of the calligraphy and strokes on the document surface 1a, and is unrelated to the color of the calligraphy and strokes. Generally, in order to read color images faithfully, a complex color separation optical system and multiple image sensors, such as those used in television cameras, are required, but in document reading devices such as facsimile and OCR, Since it targets manuscripts written in red and black or manuscripts marked in a specific color, there is little need for faithful color reproduction. Therefore, a device that can discriminate colors using a simple device is desired.

An object of the present invention is to provide a document reading device that can separate and read a plurality of colors on a document using an optical system as simple as that of the conventional reading device shown in FIG.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, 6 is a red fluorescent lamp and 7 is a blue fluorescent lamp. Portions indicated by other symbols indicate the same portions as in FIG.

In this invention, the document 1 is conveyed intermittently in synchronization with the main scanning of the solid-state image sensor 5, and the red fluorescent lamp 6 and the blue fluorescent lamp 7 are sequentially turned on during the period when the document 1 is stopped. illumination light is alternately emitted onto the document surface, a red signal and a blue signal, which are photoelectrically converted electrical color signals, are taken out from the solid-state image sensor 5, and a predetermined calculation is performed on the red signal and the blue signal, A red part signal, a blue part signal, a black part signal, and a white part signal indicating the respective color parts are separately formed.

Next, the operation of the configuration shown in FIG. 2 will be explained with reference to the time chart shown in FIG.

The solid-state image sensor 5 continuously scans as shown in FIG. 3A. As is well known, a solid-state image sensor operates in an accumulation mode. That is, the signal accumulated in the n ₀ scanning period is output in the next n ₀₁ scanning period, and the signal accumulated in the n ₀₁ scanning period is output in the next n ₀₂ scanning period. In this way, signals are accumulated and output simultaneously during one scanning period, and photoelectric conversion is performed sequentially. Therefore, as shown in FIG. 3B and C, the red fluorescent lamp is turned on during the scanning periods n ₀ , n ₁ , n _{2 .} . . and the blue fluorescent lamp is turned on during the scanning periods n ₀₁ , n ₁₁ , n ₂₁ . When the fluorescent lamp is turned on, a red signal is obtained during scanning periods n ₀₁ , n ₁₁ , n _{21 .} . . and a green signal is obtained during scanning periods n ₀₂ , n ₁₂ , n ₂₂ . At this time, as shown in FIG. 3E, if the original is transported so that the original moves by one line while the red fluorescent lamp 6 and the blue fluorescent lamp 7 are off, and the original stops while the red fluorescent lamp 6 and blue fluorescent lamp 7 are turned on. , a pair of red and blue signals is obtained for every scanning line on the document surface, that is, for each line.

Next, a method of separating and forming color portion signals, namely, a red portion signal, a blue portion signal, a black portion signal, and a white portion signal, from the red signal and the blue signal will be explained.

FIG. 4 shows the spectral reflectance characteristics for each color of red, blue, black printed on the original surface, and white of the background of the original surface. Now, a fluorescent lamp having a radiation wavelength band of 600 to 650 nm as shown in FIG. 5 is used as the red fluorescent lamp 6, and a fluorescent lamp having a radiation wavelength band of 400 to 500 nm is used as the blue fluorescent lamp 7. use. This is convenient because there is a large difference in reflectance between red and blue in each wavelength band (see FIG. 4). The red signal (denoted as Vr) and the blue signal (denoted as Vb) at this time are subjected to signal processing by the color separation circuit 15 shown in FIG.

In FIG. 6, 8 is a delay circuit, 9 is a subtraction circuit, 10, 11 and 12 are value converting circuits, 13 is a gate circuit, and each of the circuits 9 to 13 is an arithmetic circuit 14.
It consists of The operation of the color separation circuit 15 in FIG. 6 will be explained with reference to the signal waveform diagram in FIG. 7.
Now, as shown in Figure 7A, the document surface is scanned in the direction of the arrow to detect the red light based on the light from the red fluorescent lamp.
Obtain Vr and Vb based on the light from the blue fluorescent lamp. The red signal Vr and the green signal Vb are shown in Figure 7 B and C, respectively.
Shown below. Next, after delaying the red signal Vr by one scanning period in the delay circuit 8, the red signal Vr is
A difference signal Vr-b is generated by subtracting the green signal Vb from the signal Vb.
As shown in FIG. 7D, the difference signal Vr-b is a positive signal in the red portion, a negative signal in the blue portion, and a signal level close to zero in the black and white portions. Now, when the difference signal Vr-b is converted into a binary signal by the binarization circuits 10 and 11 having threshold values indicated by y and z in the figure, the binarization circuit 10 outputs a red part signal V _R consisting of a binary signal. However, from the binarization circuit 11, a blue part signal V _B consisting of a binary signal is obtained at the respective output terminals 21 and 22. The red part signal V _R and the blue part signal V _B are shown in FIG. 7F, respectively.
and shown in G.

Next, since the red signal Vr has a large positive level in the red part and the sun-colored part, the red signal Vr is converted into a binarization circuit 12 having a threshold value shown at x in FIG. 7B.
When a binary signal _{is converted with}
V _BK is obtained. Therefore, when the blue part signal V _B is removed from the mixed signal V _B +V _BK by the gate circuit B, the black part signal V _BK is obtained at the output terminal 23. Further, a portion where the red portion signal V _R , the blue portion signal V _B and the black portion signal U _BK do not exist becomes a white portion signal (referred to as V _W ).

The multicolor original reading device according to the present invention is based on a sequential reading method and uses only one solid-state image sensor. Therefore, compared to a television camera or the like that uses a color separation filter and a plurality of image pickup elements, there is no need to adjust the optical system with extremely high precision. Furthermore, there is basically no deterioration in color separation due to variations in the characteristics of the solid-state image sensor or poor adjustment of the optical system, which is very advantageous in terms of high resolution.

In the above embodiment, an example has been described in which the red fluorescent lamp 6 and the blue fluorescent lamp 7 are used to separate the red part, blue part, and black part on the document surface 1a and take it out as a signal. It is also possible to realize this by changing the color. For example, if a red fluorescent lamp and a green fluorescent lamp are used as the fluorescent lamps, the red, green, and black parts of the document surface can be separated and extracted. Furthermore, the configuration of the color separation circuit shown in FIG. 6 can be realized by various modifications.

Furthermore, the present invention can also be applied to reading surface information by arranging solid-state image sensors two-dimensionally. That is, the entire surface of the document is sequentially illuminated with two fluorescent lamps that emit illumination light with different spectral radiation distributions, and the resulting photoelectric conversion signal (color signal) is processed using a circuit configuration similar to that shown in Figure 6. By doing so, color separation is possible.

As described above, according to the present invention, by alternately illuminating a document with two colors of illumination light having different radiation characteristics and processing the obtained two color signals with a simple circuit, white and black can be included. can be separated into four color signals and extracted. In other words, color signals can be separated with high accuracy by simply making some modifications to a normal black-and-white document reading device, making it inexpensive and easy to use.
It has great practical effects, such as excellent resolution.

Furthermore, since the four color signals are completely separated and output in this way, by using these color signals, colors can be easily reproduced in a reproduction device.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the optical system of a conventional document reading device, and FIG.
Schematic configuration diagram showing the optical system of the color original reading device, Part 3
The figure is a timing chart for explaining the operation of the four-color document reading device shown in FIG. 2, FIG. 4 is a diagram showing the spectral reflection characteristics of a four-color document, and FIG. 5 is a diagram showing the spectral radiation intensity characteristics of a fluorescent lamp. 6 is a circuit showing an example of a color separation circuit, and FIG. 7 is a signal waveform diagram of each part of the color separation circuit shown in FIG. 1... Original document, 1a... Document surface, 2... Drive roller, 4... Lens, 5... Solid-state image sensor, 6...
Red fluorescent lamp (light source), 7... Blue fluorescent lamp (light source),
8...Delay circuit, 14...Arithmetic circuit, 15...Color separation circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A light source that alternately emits two colors of illumination light having different spectral radiation distributions onto the same document surface, and a light source that scans the same part of the document surface twice to reflect light from the document surface. A solid-state image sensor receives light and performs photoelectric conversion, and outputs two color signals corresponding to the two colors of illumination light. and a color separation circuit that separates and outputs color part signals indicating respective color parts of two colors, and this color separation circuit outputs one color signal corresponding to the previously emitted illumination light for one scanning period. a delay circuit that delays one color signal and the other color signal,
A four-color original reading device comprising an arithmetic circuit that generates color portion signals representing the black portion and the two color portions and outputs them to different output terminals. 2 During the stop period of the document that is intermittently transported, 2
Claim 1: Colored illumination light is emitted onto the document surface, and information is read line by line on the document surface.
4-color document reading device described in Section 1. 3. The four-color document reading device according to claim 1, wherein two-color illumination light is emitted over the entire document surface, and information on the entire document surface is read by a two-dimensionally arranged solid-state image sensor.