JPH05268476A - Original reader - Google Patents

Abstract

PURPOSE:To eliminate the noise of an original carrying stepping motor from an original read signal. CONSTITUTION:A noise waveform in each exciting pattern of an original carrying stepping motor 11 to which an exciting pulse is outputted synchronously with an original read period in a CCD 5 is detected and stored in a memory 7. Then the noise waveform is read from the memory 7 in matching with the original read synchronization and a subtractor circuit 9 takes a difference between the noise waveform and a picture signal for each exciting pattern outputted from the CCD 5 to eliminate the noise from the picture signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device applied to a facsimile device, a scanner device or the like.

[0002]

2. Description of the Related Art Conventionally, in order to reduce the size of a facsimile machine, it is necessary to integrate the electronic circuit boards for controlling the system into one small one. Generally, a digital circuit, an analog circuit, a power circuit for mechanical control of a motor and the like are mixed and mounted on the electronic circuit board.

[0003]

However, in the above-mentioned prior art, there arises a problem that noise is easily induced in the operation of each circuit in the electronic circuit board which is integrated into a small size.

In particular, the image signal read by the document information reading means such as a CCD (charge coupled device) is an analog signal, and noise on the image signal causes image contamination.

An object of the present invention is to provide an original reading device capable of removing noise of an original feeding stepping motor from an original reading signal.

[0006]

In order to achieve the above object, the present invention provides a document information reading means and a stepping motor for feeding a document in which an excitation pulse is issued in synchronization with a reading cycle of the document information reading means. And detecting noise waveforms in each excitation pattern of the stepping motor, and removing noise from the document reading signal read by the document information reading unit based on the noise waveforms in accordance with the reading cycle. It is characterized by comprising means for

In addition, a difference signal between a read signal when the stepping motor is not operating and a read signal in each excitation pattern when the stepping motor is operating for each reading cycle by the document information reading means is a noise waveform. Characterize.

Further, the noise waveform is stored in a memory as a digital value, the nozzle waveform is read out in accordance with the reading cycle and converted into an analog signal, and the noise in each excitation pattern is removed from the original reading signal.

[0009]

According to the above means, each excitation pattern in the stepping motor and the reading cycle of the document information reading means are synchronized with each other. Therefore, by detecting the noise waveform in the stepping motor in each excitation pattern. , Noise can be removed from the original reading signal based on the noise waveform in accordance with the reading cycle.

Further, a read signal (white waveform) obtained by reading a reference image (for example, a white surface) without operating the stepping motor by the document information reading means and a read signal obtained by operating the stepping motor to read the reference image This difference signal can be used as the noise waveform by taking the difference with

Further, the noise waveform which is an analog waveform is converted into a digital signal and stored, and the noise waveform is read out in accordance with the reading cycle of the document information reading means and converted into an analog signal. By removing the noise in the excitation pattern, the noise is accurately removed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a schematic structure of an embodiment of the present invention, in which 1 is an original, 2 is an original 1 pressed to a predetermined position, and the surface is white-painted so that the original 1 is white. A pressure plate serving as a level reference member, 3 is a light source for illuminating the original 1, 4
Is a focusing lens for forming an image of the document 1 on the CCD 5 which is the document information reading means.

Further, 6 is an A / D (analog / digital) conversion circuit, 7 is a non-volatile memory, 8 is a D / A conversion circuit,
Reference numeral 9 is a subtraction circuit, 10 is a binarization circuit, 11 is a stepping motor for conveying originals, 12 is a motor driver, 13 is a CPU (central processing unit) for controlling the above-mentioned units, and 14 is a data bus.

In FIG. 1, at the time of reading the original, the reading surface of the original 1 is illuminated by the light source 3 and an image is formed on the light receiving surface of the CCD 5 by the focusing lens 4. The CCD 5 photoelectrically converts and outputs an image signal. The image signal is subjected to noise removal processing, which will be described later, and then subjected to known shading, shading adjustment, and halftone processing in the binarization circuit 10 and output as a binary signal.

Next, a method of extracting a noise waveform will be described with reference to the waveform diagram of FIG. 2 and the flowchart of FIG.

[0017]

[Outer 1]

It is issued in synchronization with the reading cycle of the CCD 5.
In this embodiment, there are two types of excitation patterns from the state of pulse output.
(A pattern, B pattern) can be distinguished.

In each of the excitation patterns A and B, the white coating surface of the pressure plate 2 is read while the stepping motor 11 is not operated, and the white waveform Y is obtained from the CCD 5 (S1-1). The white waveform Y is converted into a digital signal by the A / D conversion circuit 6 and stored in the memory 7 (S1-2). Next, the stepping motor 11 is operated to read the white coated surface of the pressure plate 2, and the white waveform X with noise is obtained from the CCD 5 (S1-3).

Here, the data of the white waveform Y is read from the memory 7 and converted into an analog signal by the D / A conversion circuit 8 to reproduce the white waveform Y (S1-4), and the subtraction circuit 9 outputs the white waveform. The noise waveform Z is extracted by taking the difference between X and the white waveform Y.
(S1-5). This noise waveform Z is returned to the A / D conversion circuit 6 again.
Is converted into a digital signal by and stored in the memory 7 (S1
-6).

Next, the noise removal method will be described with reference to the waveform chart of FIG. 4 and FIG.
This will be described with reference to the flowchart in FIG.

At the time of reading the original, the image signal W containing noise is output from the CCD 5 in synchronization with the excitation patterns A and B of the stepping motor 11 (S2-1). Corresponding to each excitation pattern A, B of the image signal W, noise waveform data is read from the memory 7, converted into an analog signal by the D / A conversion circuit 8, and the noise waveform Z is reproduced (S2- 2).
By subtracting the image signal W and the noise waveform Z in the subtraction circuit 9 (S2-3), the noise-removed image signal V is output to the binarization circuit 10 (S2-4).

As described above, the noise generated during the operation of the stepping motor 11 can be removed from the image signal,
It is possible to prevent the output image based on this image signal from being adversely affected by noise such as dirt, black-and-white inversion, and false gradation.

[0024]

As described above, according to the present invention,
The noise waveform detected for each excitation pattern of the stepping motor enables noise removal from the image signal (original reading signal), so noise removal can be ensured with a simple configuration. It can be easily extracted from the difference between the read signals during operation and during operation, and the noise waveform can be accurately removed by storing the noise waveform in memory and reading the noise waveform in accordance with the read cycle. Therefore, it is possible to provide a document reading apparatus capable of eliminating the noise of the stepping motor.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of a document reading apparatus of the present invention.

FIG. 2 is a waveform diagram for explaining a noise waveform extraction method.

FIG. 3 is a flowchart of a noise waveform extraction method.

FIG. 4 is a waveform diagram for explaining a noise removal method.

FIG. 5 is a flowchart of a noise removing method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original, 2 ... Pressure plate, 5 ... CCD (original information reading means), 6 ... A / D conversion circuit, 7 ... Memory, 8 ... D
/ A conversion circuit, 9 ... Subtraction circuit, 10 ... Binarization circuit,
11 ... Stepping motor, 12 ... Motor driver,
13 ... CPU.

Claims (3)

[Claims] 1. An original reading device comprising an original information reading means and a stepping motor for feeding an original which outputs an exciting pulse in synchronization with a reading cycle of the original information reading means. Each exciting pattern of the stepping motor. The document reading apparatus further comprises means for detecting a noise waveform in the document and removing noise from a document reading signal read by the document information reading unit based on the noise waveform in accordance with a reading cycle. 2. A noise waveform is a difference signal between a read signal when the stepping motor is not operating and a read signal in each excitation pattern when the stepping motor is operating for each reading cycle by the document information reading means. The document reading apparatus according to claim 1, wherein: 3. The noise waveform is stored in a memory as a digital value, the nozzle waveform is read out in accordance with the reading cycle and converted into an analog signal, and the noise in each excitation pattern is removed from the original reading signal. The document reading device according to claim 1 or 2.