JPH0642714B2 - Image reader - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and in particular, in a copying machine, a facsimile, or the like, a reflected light from an original is imaged on a light receiving element to obtain image information. The present invention relates to an image reading device for reading an image.

[Prior Art] Conventionally, in a reading device of a copying machine or a facsimile device,
A white reference plate of uniform density is provided in order to correct shading distortion caused by the influence of the optical system and the light source. However, this white reference plate has a problem that it is not exposed to the strong light of the light source during long-term use, and it is discolored or dust or dirt adheres to it, so that the initial density cannot be obtained.

An object of the present invention is to detect deterioration of a correction function when correcting a read image signal by using a reference signal obtained by reading a reference member having a uniform density in an image reading apparatus, and to correct the deterioration. An object of the present invention is to provide an image reading device that compensates for deterioration of function.

Embodiment of the Invention FIG. 1 is an explanatory view showing an embodiment of the present invention.

The original 7 is irradiated with light from the light source 3, and reflected light from the original 7 is received by the solid-state image sensor 1 as a light receiving element via the lens 2.

Further, a white original document holding means which is in contact with the back surface of the original document 7 and whose reading position is white is provided, and the white portion of the white original document holding means is the reading white background 4.

The moving white background member 5 moves only when a moving signal is received, contacts the front surface of the original 7, and moves to the upper part of the original reading position. The solenoid 6 moves the moving white member 5. It is one of the means. The A / D converter 8 converts the analog image information from the image sensor 1 into digital image information.

The storage device 9 stores the image information by the reflected light from the read white background 4 as a white document holding means. The binarization circuit 10 is a circuit that converts predetermined information into a binary signal. The comparison circuit 11 compares the image information by the reflected light from the moving white background member 5 with the image information stored in the storage circuit 11.

The control unit 12 is one of abnormality detecting means that detects an abnormality of the light source 3 or an abnormality of the shading waveform of the image information on the read white background 4 based on the output signal of the comparison circuit 11.

Next, the operation of the above embodiment will be described.

The image sensor 1, the lens 2, and the light source 3 are examples of a reading unit that reads an original image, and the read white background 4 is an example of a first reference member having a uniform density.
Is an example of a correction unit that corrects the image signal read by the reading unit based on the first reference signal obtained by reading the first reference member by the reading unit. The moving white background member 5 is an example of a second reference member having a uniform density, and the storage device 9, the comparison circuit 11, and the control unit 12 are examples of deterioration compensation means.
The deterioration compensating means compares the second reference signal obtained by reading the second reference member by the reading means with the first reference signal, so that the correcting means corrects the read image signal using the first reference member. Is used to detect deterioration of the correction function of the correction means using the second reference signal.

FIG. 2 is a diagram showing a signal waveform of a main part of FIG.
FIG. 3 is a diagram showing an abnormal state, and FIG. 3 is a flowchart showing the operation of the above embodiment.

First, the cueing of the original 7 is stopped (S1), and the read white background 4 is prescanned (S2). Then, the storage device 9 stores the image information at the time of the prescan.

Next, by operating the solenoid 6, the document 7
The moving white background member 5 that is in contact with the front side of is moved to the document reading position, and the moving white background member 5 is pre-scanned (S3).

Then, the comparison circuit 11 performs comparison (S4).
That is, the image information by the reflected light from the moving white background member 5 is compared with the image information stored in the storage device 9. If the control unit 12 does not detect an abnormality in the shading waveform of the image information on the read white background 4 (S
5) Using the data of the read white background 4 (S6), the document is moved to read the image (S7), and the image processing is performed (S8).

On the other hand, in S5, when the control unit 12 detects an abnormality in the shading waveform, the abnormality is displayed on the CRT or the like (S11), and instead of using the data from the read white background 4, the data from the moving white background member 5 is used. Is used (SI
2). After that, the same operations as S7 and S8 are performed, and the entire image processing is completed.

For example, the output signal of the storage device 9 when the read white background 4 is read is as shown in FIG. 2A, and the output signal of the A / D converter 8 when the moving white background member 5 is read. 2 (2), the comparison circuit 11 subtracts the waveform of FIG. 2 (1) from the waveform of FIG. 2 (2) and outputs the signal of the waveform of FIG. 2 (3). . Thus, when the output signal of the comparison circuit 11 is not 0, the control unit 12
However, it is determined that an abnormality has occurred in the shading waveform.

Instead of the abnormality display (S11), an abnormality output (S13) may be performed by a printer or the like.

EFFECTS OF THE INVENTION According to the present invention, in a reading device that corrects a read image signal by a reference signal obtained by reading a reference member having a uniform density, by comparing read signals of two reference members, Deterioration of the correction function of the read image signal is detected, and deterioration of the correction function of the read image signal using one reference signal is compensated for using the other reference signal, so that image reading using an appropriate reference signal is always performed. There is an effect that correction can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention. FIG. 2 is a diagram showing a main part waveform in the above-mentioned embodiment, and is a diagram showing an abnormal state. FIG. 3 is a flow chart showing the operation of the above embodiment. DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor, 3 ... Light source, 4 ... White reading background as white document holding means, 5 ... Moving white background member, 6 ... Solenoid as moving means, 9 ... Storage device, 11 ... Comparison circuit, 12 ... Abnormality detecting means As a control unit.

Claims (1)

[Claims] 1. A reading means for reading an original image; a first reference member having a uniform density; a reading means for reading the first reference member based on a first reference signal obtained by the reading means. A correction means for correcting the read image signal; a second reference member having a uniform density; and a second reference signal obtained by reading the second reference member by the reading means and the first reference signal. By
Deterioration compensation means for detecting deterioration of the correction function of the read image signal using the first reference member by the correction means, and compensating deterioration of the correction function of the correction means using the second reference signal; An image reading device having.