JPH0583550A - Image input device - Google Patents

Abstract

PURPOSE:To correct dispersion in the sensitivity of a light source converting element, etc., to read the pictures of an original by a facsimile equipment or the like. CONSTITUTION:First of all, shading data obtained by picking the image of a blank screen are coded by an A/D converter 2 and stored in a memory 3 while using a photoelectric converter 1 composed of a CCD image sensor, etc., and next, the output of the photoelectric converter 1 from the original picture is similarly converted by the A/D converter 2. Both signals are compared by a comparator 5, and the output of a divider 4 dividing both signals is corrected by a correcting circuit 6 so as to obtain an output signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device used for a facsimile machine or the like, in which variations in sensitivity of light sources and photoelectric conversion elements are corrected.

[0002]

2. Description of the Related Art In recent years, various image input devices used in association with the demand for household facsimiles and DTP (desktop publishing) have been actively developed.

A conventional image input device will be described below with reference to the drawings. As shown in FIG. 3, an output signal from the photoelectric conversion unit 1 for reading a document is input to the A / D converter 2 and encoded into digital data, and then stored in the memory 3. Next, the output of the A / D converter 2 and the output from the memory 3 are added to the divider 4 and output.

The operation of the image input device configured as described above will be described below. First, before reading an original, a photoelectric conversion unit 1 captures an image using a blank screen, the output is encoded by an A / D converter 2, and stored in a memory 3 as shading data. Next, the original screen is similarly read by the photoelectric converter 1, the signal is digitally encoded by the A / D converter 2, the output signal is added to the divider 4, and the shading data previously stored in the memory 3 is used. By removing the difference, it is possible to correct the variation of the light source and the variation of the output of the photoelectric converter 1, and obtain the data corresponding to the density of the document.

[0005]

However, in the above-mentioned conventional configuration, when the data for reading the original becomes larger than the shading data, the division result becomes larger than 1. However, this integer part is not output and the data below the decimal point is output. To be done. Therefore, since the output of the divider rapidly changes from the maximum value to the minimum value, there is a problem that even if a white original is read, a black dot appears due to the influence of noise.

The present invention solves the above-mentioned conventional problems, and provides an image input device for forcibly correcting the output of a divider in order to prevent black and white inversion due to noise or the like input during shading correction. The purpose is to do.

[0007]

In order to achieve the above object, the image input apparatus of the present invention comprises a comparing means and a dividing means for comparing the data from the encoding means with the data stored in the storage means. And a means for correcting the output to the maximum value.

[0008]

With the above arrangement, the present invention can prevent the disturbance of the document due to noise or the like when the shading correction is performed using the divider.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an A / D converter 2 for digitally encoding an output from a photoelectric converter 1 using a CCD image sensor and a memory 3 as a storage means.
And the divider 4, the comparator 5, the correction circuit 6 and the like.

The operation of the image input device configured as described above will be described with reference to FIG. First, before reading an original, a blank screen is imaged by using the photoelectric converter 1 configured by a CCD image sensor or the like to obtain so-called shading data. The data is encoded by digital conversion using the A / D converter 2, and the data is stored as shading data in the memory 3 configured by SRAM or the like. Next, the original screen is read by the photoelectric converter 1 to read it, and its output is converted into digital data by the A / D converter 2 and input to the divider 4 together with the shading data stored in the memory 3. The divider 4 divides the read data by the shading data.

On the other hand, the output from the A / D converter and the output from the memory 3 are also input to the comparator 5 and are compared with each other. If the output is "1", it is smaller than the shading data read data. It corresponds.

Here, as shown in FIG. 2, by ORing each bit of the output from the divider 4 and the output from the comparator 5, all the output bits are corrected to "1" to obtain the output. ing.

[0014]

As can be seen from the above embodiments, the present invention can realize an excellent image input device capable of removing the influence of noise and the like with a simple circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of an image input device according to an embodiment of the present invention.

FIG. 2 is a correction circuit diagram of the embodiment.

FIG. 3 is a block diagram of a conventional image input device.

[Explanation of symbols]

 1 Photoelectric Converter 2 A / D Converter 3 Memory (SRAM) 4 Divider 5 Comparator 6 Correction Circuit

Claims (1)

[Claims] 1. A photoelectric conversion means comprising a plurality of photoelectric conversion elements, an encoding means for A / D converting a signal from the photoelectric conversion means into digital data, and the digital data corresponding to each photoelectric conversion element. And a memory of storage means to store,
A division means for dividing the data from the encoding means by the data stored in the storage means; and a comparison means for comparing the data from the encoding means with the data stored in the storage means, If the data from the encoding means is larger than the data stored in the storage means,
An image input device configured to correct the output from the dividing unit to a maximum value.