JPH02151985A - Image pickup device - Google Patents

Abstract

PURPOSE:To improve interchangeability between business form drop-out color machines to be operated and an S/N by determining the output of each picture element based upon a result obtained by comparing and computing video signal data obtained while irradiating an object to be pickup up with light beams having respectively different wavelength bands in each scanning. CONSTITUTION:After ending the writing of video signal data 1 for one scanning in a memory 106, a timing circuit 110 turns off a red LED 101, turns on a green LED 102 having a different wavelength band, switches a multiplexer 105 to the memory 107 side and writes the video signal output data 1 in the memory 107. The signal data are read out from the memories 106, 107 by successively counting up the contents of a memory address counter 108. The read video signal data 2, 3 are computed by a comparing arithmetic circuit 109 and the output of the image pickup device is determined and successively outputted. Consequently, interchangeability between the machines and the S/N can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an imaging device, and particularly to an imaging device for an optical character reader (hereinafter referred to as OCR).

[Conventional technology]

Conventionally, an OCR imaging device includes a light source that illuminates the surface of a document, an image sensor that converts the document image into a video signal, and a reflecting mirror, lens, etc. that forms the document image on the image sensor. Each component has its own spectral radiation characteristics, spectral reflection characteristics, and spectral sensitivity characteristics, and the spectral sensitivity characteristics of the imaging device are the overall characteristics of these components.

[Problem to be solved by the invention]

As mentioned above, since the spectral sensitivity of the imaging device differs depending on its components, the types of dropout colors that can be used differ depending on the OCR model, and there is a disadvantage that there is no compatibility between the dropout color models that can be used. be.

Also, in order to specifically drop out only certain colors,
When using an optical filter, the S/
There is a drawback that the N ratio becomes poor and the image for OCR recognition may become defective.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, significantly improve the compatibility between models of dropout colors of operational forms, and significantly improve the deterioration of the S/N ratio due to dropout of only specific colors. An object of the present invention is to provide an imaging device that achieves the following.

[Means to solve the problem]

The imaging device of the present invention includes: a light-emitting device that sequentially and repeatedly emits light in at least two different wavelength bands ranging from the visible region to the near-infrared region; and an imaging device whose field of view is an object illuminated by the light-emitting device; storage means for storing at least one scanning period of video signal data output from the imaging means during each light emission period in each wavelength band of the light emitting means, and corresponding to the same pixel of the video signal data stored in the storage means; and comparison calculation means for comparing the magnitudes of data in each wavelength band of the light emitting means, determining an output for each of the same pixels based on the comparison result, and sequentially outputting the determined output.

〔Example〕

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

FIG. 1 is a block diagram of an embodiment of the present invention. The embodiment shown in FIG. 1 includes a red LEDIO1, a green LEDIO2. L
ED drive circuit 103. Imaging circuit 104 including an image sensor. Multiplexer 105, memory 106, 10
7. Memory address counter 108. Comparison calculation circuit 10
9. Timing circuit 110. Motor drive circuit 111. It is configured with a motor 112 and a form conveyance system 113, and a form 5 is also shown.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

When the form 5 to be read enters the field of view of the imaging circuit 104, the timing circuit 110 outputs an LED switching signal 115.
The LED drive circuit 103 is driven by the red LED.
101 and sends a multiplexer switching signal 117 to switch the multiplexer 105 to the memory 106.
Switch to the side.

When the light emission of the LED 101 becomes stable, the imaging circuit 104
In synchronization with the synchronization signal 116 output from the imaging circuit 10
4 is written into the memory 106 for one scanning line period.

Video signal data 1 is digital data whose white level is normalized to 100%.

Writing to the memory 106 is performed by counting up the address counter 108 using the count up signal 118 output from the timing circuit 110, sequentially updating the memory address using the memory address signal 119, and activating the memory write signal 120. conduct.

- When the writing of the video signal data 1 for the scanning line into the memory 106 is completed, the timing circuit 110 turns on the red LED.
101 is turned off, the green LED 102 is turned on, the multiplexer 105 is switched to the memory 107 side, and video signal output data 1 is written to the memory 107 in the same manner as above.

When writing to the memories 106 and 107 is completed, the timing signal 121 opens the multiplexer 105 output, and the address counter 108 is opened as in the case of writing.
The video signal data is read from the memories 106 and 107 by sequentially counting up j times.

The video signal data 2 and 3 that have been read out are subjected to the following computations by a comparison arithmetic circuit, and the output of the image pickup apparatus is determined and sequentially output.

The output is determined by (video signal data 2) - (video signal data 3) l with K as a constant.
>K, output - white level (100%) (video signal data 2) - (video signal data 3)]
If ≦K, the average value of output-video signal data 2 or 3 is determined.

The above timing is illustrated in FIG.

Now, as an example, the form 5 is a form on which a character frame is printed using the spectral reflection characteristics 303 of the green dropout color shown in FIG.
1 is entered as shown in FIG.

As shown in FIG. 4, in the video signal in which the portion indicated by the arrow 51 is illuminated and scanned with a red LED, that is, the video signal data 2 in FIG. 1, the character frame portion appears dark.

Furthermore, in the video signal 404 obtained by illuminating and scanning the portion indicated by the arrow 51 with a green LED, that is, the video signal data 3 in FIG. 1, the character frame portion appears relatively faint.

That is, video signal data 2 and 3 have different densities of character frames.

On the other hand, since the spectral reflection characteristics of the black color of a pencil have the 300 characteristics shown in Figure 3, the density of the text written in the pencil on the video signal will be affected regardless of whether the red or green LED is lit. There is no big difference.

By appropriately selecting the value of K in consideration of these conditions, only the portions of the video signal data 23 that have approximately the same density, that is, the portions of the handwritten characters 401 written in pencil, appear on the output signal. The characters appear, and the parts with different densities, ie, the character frame parts, disappear.

In addition, red dropout color spectral reflection characteristics 304
In the case of , the relationship between the video signals 2.3 is reversed as shown in parentheses in FIG. 4, but only the character frame portion disappears in the same way as above.

In this way, even if the character frame is printed in a dropout color such as edge thread or red, it is possible to erase it from the video signal.

As described above, writing to the memories 106 and 107 is performed using the red L
One scan of this imaging device is performed by sequentially scanning with the ED 101 and the colorless LED 102 lit, then reading out these memories, performing calculations, and reading out the video signal data 4 from which dropout colors have been removed. ends.

After this, in order to perform the next scan, the timing circuit 110
drives the motor drive circuit 1]1, and drives the motor 112
is rotated, and the above-described process is then repeated.

In this way, it becomes possible to carry out imaging processing in which the constraints of one drop-out color are significantly relaxed.

In addition, in the above-mentioned embodiment, the case where video signal data of the investigation period was handled using light of two wavelength bands was explained as an example, but when the light of two or more wavelength bands is used or - It is clear that the same process can be easily carried out by repeating the same process even when dealing with video signal data for a period longer than that.

[Effects of the Invention] As explained above, according to the present invention, at least one video signal data obtained while illuminating an object to be imaged with light in at least two different wavelength bands from the visible region to the near-infrared region is By determining the output for each pixel based on the results of comparative calculations for each investigation period, it significantly improves the compatibility between models of dropout color of operational forms, and also allows only specific colors to be dropped out depending on the model. This has the effect of significantly improving the deterioration of the S/N ratio caused by this.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is an operation timing diagram of the embodiment of Fig. 1, and Fig. 3 is a spectral characteristic of the light source and dropout of a form in the embodiment of Fig. 1. A color spectral reflection characteristic diagram, FIG. 4, is an explanatory diagram showing the content of dropout of the character frame in the embodiment of FIG. 1. 1... Video signal output data, 2.3... Video signal data, 4... Video signal output data, 5... Form, 101... Red LED, 102... Green LED, 1
03... LED) Nilive circuit, 104... Imaging circuit, 105... Multiplexer, 106, 107...
...Memory, 108...Memory address counter, 1
09... Comparison daily calculation circuit, 110... Timing circuit,
111...Motor drive circuit, 112...Motor, 1
14... Form transport system, 115... LED switching signal,
116... Synchronization signal, 117... Multiplexer switching signal, 118... Count up signal, 119...
Memory address signal, 120...Memory write signal, 2
00...Investigation calculation output-cycle, 201...Red LED
Input period of video signal data by green LED, 202... Input period of video signal data by green LED, 203...
- Calculation result output period, 300... Spectral reflection characteristics of black pencil, 301... Spectral characteristics of optical system determined by colored LEDs and image sensor, 302... Green L E D
and the spectral characteristics determined from the image sensor, 303... The spectral reflection characteristics of the green dropout color, 304...
・Spectral reflection characteristics of red dropout color, 401
...Handwritten characters with a pencil, 402...Character frame printed with dropout color, 403...Form 5
Illuminate the part indicated by the arrow with a red (or green) LED.
Video signal at the time of Ih, 404... Video signal at noon when illuminated with green (or red) LED, 405
;...Video signal after comparison calculation.

Claims (1)

[Claims] a light-emitting means that sequentially and repeatedly emits light in at least two different wavelength bands ranging from a visible region to a near-infrared region; an imaging means whose field of view is an object illuminated by the light-emitting means; and each wavelength band of the light-emitting means. storage means for storing at least one scanning period of video signal data output from the imaging means during each light emission period;
Comparing the magnitude of data in each wavelength band of the light emitting means corresponding to the same pixel of the video signal data stored in the storage means, determining the output for each of the same pixels based on the comparison result, and sequentially outputting the determined output. An imaging device comprising a calculation means.