JP2002218237A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need of providing a white reference board beforehand. SOLUTION: At the time of shipping from a plant or the like, by an image sensor 1, a white reference original 8 on which nothing is written is irradiated with light from a light source 9, reflected light from the white reference original 8 is received and white reference signals 13 which are the image signals 10 of the white reference original 8 are outputted. By a highest value detection part 3, the highest value of the white reference signals 13 outputted by the image sensor 1 is detected and the detected highest value is stored in a storage part 4 as a reference value 14. Under a user at the shipping destination of this image reader, by the image sensor 1, the reflected light from an original 7 is received and the image signals 10 of the original 7 are outputted. By an A/D conversion part 2, the image signals 10 outputted by the image sensor 1 are binarized by the reference value 12 for which the reference value 14 stored in the storage part 4 is corrected on the basis of the change rate of the irradiation light quantity of the light source 9 similarly stored in the storage part 4 beforehand and they are outputted as binary images 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus which irradiates light from a light source onto a document and outputs an image of the document as a binary image based on light reflected from the document.

[0002]

2. Description of the Related Art Conventionally, this type of image reading apparatus is used to binarize reflected light from a document to be read and read the document as a binary image.

[0003] Referring to FIG. 4 which is a block diagram of this conventional image reading apparatus, the conventional image reading apparatus comprises:
Before reading the original 7, the light from the light source 9 is irradiated on a white reference plate provided in advance to detect a change in the light amount of the light source 9 of the apparatus, and the reflected light from the white reference plate is reflected by the image sensor 1. A white reference signal, which is the image signal 10 of the white reference plate, is output, and the maximum value detection unit detects the maximum value of the white reference signal output from the image sensor 1, and outputs the detected maximum value from the image sensor 1. A / D converter 2 as a reference value for binarizing image signal 10
Then, when reading the original 7, the original 7 is irradiated with light from the light source 9, the image sensor 1 receives the reflected light from the original 7, and receives the image signal 1 of the original 7.
0, and the A / D converter 2 outputs the image sensor 1
Are binarized based on the reference value and output as a binary image 11.

[0004]

In the above-described conventional image reading apparatus, the light from the light source is applied to a white reference plate provided in advance to detect a change in the light amount of the light source of the apparatus before reading the original. Then, the image sensor receives the reflected light from the white reference plate and outputs a white reference signal. The maximum value detection unit detects the maximum value of the white reference signal, and determines the maximum value of the image signal from the image sensor. It is set in the A / D converter as a reference value for conversion into a value, and when reading the original, the original is irradiated with light from a light source.
The image sensor receives reflected light from the document and outputs an image signal of the document, and the A / D converter binarizes the image signal output by the image sensor based on a reference value and outputs it as a binary image. Since the highest value of the white reference signal detected based on the reflected light from the provided white reference plate is used as a reference value for binarizing the image signal of the document, it is necessary to provide a white reference plate in advance, There is a problem that it takes time to secure a mounting space for assembling the white reference plate to the present apparatus and to assemble the white reference plate.

An object of the present invention is to eliminate such a conventional drawback, and it is not necessary to provide a white reference plate in advance, and it is not necessary to secure a mounting space for assembling the white reference plate to the present apparatus. An object of the present invention is to provide an image reading apparatus that does not require assembling steps of a board.

[0006]

A first image reading apparatus of the present invention irradiates an original with light from a light source and outputs an image of the original as a binary image based on reflected light from the original. An image sensor that receives the reflected light from the document and outputs an image signal of the document, and a reference value obtained by correcting a predetermined reference value based on a predetermined change rate of the amount of light emitted from the light source. And an A / D converter for binarizing the image signal output from the image sensor and outputting the image signal as the binary image.

The first image reading device of the present invention irradiates the white reference document with light from the light source before receiving the reflected light from the document and outputting the image signal. An image sensor that receives reflected light from a white reference original and outputs a white reference signal that is an image signal of the white reference original; and detects the highest value of the white reference signal output by the image sensor, and detects the detected maximum value. A maximum value detection unit that sets a value to the predetermined reference value.

A second image reading apparatus according to the present invention is an image reading apparatus which irradiates light from a light source onto a document and outputs an image of the document as a binary image based on reflected light from the document. An image sensor that receives the reflected light from the image sensor and outputs an image signal of the original; and a storage unit that stores in advance a reference value used when binarizing the image signal and a change rate of the amount of light emitted from the light source. Binarizing the image signal output by the image sensor with a reference value obtained by correcting the reference value stored in the storage unit based on the change rate of the light amount stored in the storage unit in advance. And an A / D converter that outputs the value image.

A third image reading apparatus according to the present invention is directed to an image reading apparatus which irradiates light from a light source onto a document and outputs an image of the document as a binary image based on reflected light from the document. An image sensor that receives the reflected light from the image sensor and outputs an image signal of the original; and a storage unit that stores in advance a reference value used when binarizing the image signal and a change rate of the amount of light emitted from the light source. A reference value setting unit that reads the reference value and the change rate of the light amount from the storage unit, corrects the reference value based on the change rate of the light amount, and outputs the corrected reference value, and a reference value setting unit. An A / D conversion unit that binarizes the image signal output by the image sensor based on the output reference value and outputs the image signal as the binary image. .

The second and third image reading devices of the present invention apply the light from the light source to a white reference document before receiving the reflected light from the document and outputting the image signal. The image sensor that irradiates and receives reflected light from the white reference document and outputs a white reference signal that is an image signal of the white reference document; and detects and detects the maximum value of the white reference signal output by the image sensor. A maximum value detection unit that stores the maximum value obtained as the reference value in the storage unit.

In the first to third image reading apparatuses of the present invention, the rate of change of the light amount is determined by a first change rate of the light amount based on deterioration of the light source due to aging, and the light source by heat generated by the light source. And the second rate of change of the light quantity based on the temperature of the light.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the image reading apparatus of the present invention.

In the present embodiment shown in FIG. 1, a light source 9 (LE
D, cold-cathode tube, etc.) to the original 7
The image of the original 7 is converted to a binary image 1 based on the reflected light from
In an image reading apparatus that outputs the image signal 1 as an image reading signal, an image sensor 1 that receives reflected light from the original 7 and outputs an image signal 10 of the original 7,
A storage unit 4 that previously stores a reference value 14 used when binarizing 0 and a change rate of the amount of light emitted from the light source 9, and reads out the reference value 14 and a change rate of the light amount from the storage unit 4. The reference value setting unit 5 that corrects the value 14 based on the change rate of the light amount and outputs the corrected value as the reference value 12
And an A / D conversion unit 2 that binarizes the image signal 10 output from the image sensor 1 based on the reference value 12 output from the reference value setting unit 5 and outputs it as a binary image 11.

The image sensor 1 irradiates light from a light source 9 to a white white reference original 8 in which nothing is described before receiving the reflected light from the original 7 and outputting an image signal 10. It receives the reflected light from the white reference document 8 and outputs a white reference signal 13, which is the image signal 10 of the white reference document 8, and detects the maximum value of the white reference signal 13 output by the image sensor 1 by a peak hold circuit or the like. The present embodiment further includes a maximum value detection unit 3 that stores the detected maximum value as the reference value 14 in the storage unit 4.

The change rate of the amount of light stored in advance in the storage unit 4 is
It includes a first rate of change 15 in the amount of light based on the deterioration of the light source 9 due to aging and a second rate of change 16 in the amount of light based on the temperature of the light source 9 due to the heat generated by the light source 9.

The first change rate 15 of the light amount is determined by the present image reading device after the maximum value detection unit 3 detects the maximum value of the white reference signal 13 and stores it in the storage unit 4 as the reference value 14. When reading the document 7, the light amount of the light source 9 when the light source 9 is turned on in order to generate light to irradiate the document 7 is set as a reference and is determined according to the total lighting time from when the light is turned on.

The second rate of change 16 of the light amount is based on the light amount of the light source 9 when the light source 9 is turned on to generate light to irradiate the original 7 when the image sensor 1 outputs the image signal 10. The lighting time from when this was lit (hereinafter,
Described as individual lighting time. ).

FIG. 1 shows an original 7 and a white reference original 8.
To the original reading position, original 7 or white reference original 8
Out of the original reading position, turning on / off the light source 9,
The control unit 6 also controls the timer A and the timer B for measuring the total lighting time and the individual lighting time, and instructs the timer B to start measurement, and the like.

Next, the operation of the image reading apparatus according to the present embodiment will be described in detail with reference to FIGS.

FIG. 2 is a flowchart showing an example of the operation of the embodiment of the present invention.

FIG. 3 is a diagram showing an example of the relationship between the lighting time of the light source and the rate of change of the light amount, and the total lighting time (unit, hour).
And the relationship between the timer value A indicating the light amount and the first change rate 15 of the light amount, and the timer value B indicating the individual lighting time (unit: minute) and the relation between the timer value B and the second change rate 16 of the light amount. This relationship is obtained in advance through experiments or the like.

In FIG. 1, when this apparatus is shipped from a factory, for example, the control unit 6 conveys and sets the white reference original 8 to the original reading position by, for example, a roller (not shown) based on an instruction from the operator. Then, the light source 9 is turned on to irradiate the white reference document 8 with light from the light source 9. The image sensor 1 receives the reflected light from the white reference document 8, and outputs a white reference signal 13 which is an image signal 10 of the white reference document 8.
The maximum value detection unit 3 detects the maximum value of the white reference signal 13 output from the image sensor 1 by a peak hold circuit or the like, and stores the detected maximum value as the reference value 14 in the storage unit 4. Also, based on the instruction of the operator, FIG.
The first change rate 15 of the light quantity corresponding to the timer value A and the second change rate 16 of the light quantity corresponding to the timer value B are stored in the storage unit 4 in advance (S1).
The timer A, which is a timer for the total lighting time, and the timer B, which is a timer for the individual lighting time, which are provided at 0 are cleared to 0 (S
2).

When the apparatus is shipped to a user, for example, and the user reads an original 7 over several pages, for example, the controller 7 moves the original 7 to the original reading position based on the user's instruction. The document is conveyed and set by rollers (not shown) or the like (S3), and it is checked whether or not this document 7 is the first page document 7 (S4).
If it is not the page, the process continues to step 6 (S6).
When the original 7 is the first page, the light source 9 is turned on to irradiate the original 7 with light from the light source 9, and the timer A and the timer B start measuring time, and the measurement result (timer value A and timer The storage of the value B) in the storage unit 4 is started (this storage is performed in parallel with the time measurement of the timer A and the timer B) (S5). The reference value setting unit 5 includes a storage unit 4
A timer value A and a timer value B are read out from the storage unit, and a first change rate 15 of the light amount corresponding to the timer value A and a second change rate 16 of the light amount corresponding to the timer value B shown in FIG. 4 and a reference value 1 also read from the storage unit 4.
4 is multiplied by the first rate of change 15 and the second rate of change 16, and the multiplied value is output as the reference value 12 and set in the A / D converter 2 (here, the reference value setting unit 5). As shown in FIG. 3, the first change rate 15 is 1.0 when the timer value A is 0 or more and less than 50, and the first change rate 15 when the timer value A is 50 or more and less than 100, as shown in FIG.
Is read as 0.962... And the timer value B is 0
When the above is less than 0.2, the second change rate 16 is set to 1.0,
When 0.2 or more and less than 1.0, the second change rate 16 is set to 0.1.
970... ) (S6). The image sensor 1 receives reflected light from the document 7 and outputs an image signal 10 of the document 7, and the A / D converter 2 outputs an image signal output by the image sensor 1 based on the reference value 12 output by the reference value setting unit 5. 10 is binarized into a binary image 11
It is output as (image reading signal) (S7). next,
The control section 6 unloads the read original 7 with a roller or the like (S8) and checks whether there is the next page original 7 (S9). If there is the next page original 7, the next page original 7 is removed. The process continues to step 3 in order to convey the document to the original reading position by using rollers or the like. Manuscript 7 of the next page
If there is no light, the light source 9 is turned off and the timer B is cleared to 0 (S10).

[0025]

As described above, according to the image reading apparatus of the present invention, the image sensor receives the reflected light from the original and outputs an image signal of the original, and the A / D converter determines the image signal in advance. In order to binarize the image signal output by the image sensor based on the reference value corrected based on the predetermined change rate of the light amount irradiated by the light source, and output the image signal as a binary image, the predetermined reference value Since a binary image is obtained by binarizing the image signal with a reference value corrected based on a predetermined change rate, a white reference plate for detecting a change in the light amount of the light source of the apparatus before reading the original is used. There is no need to prepare in advance, so there is no need to secure a mounting space for assembling the white reference plate to the present apparatus, and the number of steps for assembling the white reference plate can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of an image reading apparatus according to the present invention.

FIG. 2 is a flowchart illustrating an example of an operation according to the exemplary embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a relationship between a lighting time of a light source and a change rate of a light amount.

FIG. 4 is a block diagram of a conventional image reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image sensor 2 A / D conversion part 3 Maximum value detection part 4 Storage part 5 Reference value setting part 6 Control part 7 Original 8 White reference original 9 Light source 10 Image signal 11 Binary image 12 Reference value 13 White reference signal 14 Reference value 15 First rate of change 16 Second rate of change

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (9)

[Claims] 1. An image reading apparatus which irradiates light from a light source onto a document and outputs an image of the document as a binary image based on reflected light from the document, wherein the document receives the reflected light from the document. An image sensor that outputs an image signal of the image signal, and binarizes the image signal output by the image sensor with a reference value obtained by correcting a predetermined reference value based on a predetermined change rate of the amount of light emitted from the light source. An image reading apparatus comprising: an A / D converter that outputs a binary image. 2. A method for irradiating a white white reference original with light from the light source and receiving reflected light from the white reference original before receiving the reflected light from the original and outputting the image signal. The image sensor that outputs a white reference signal that is an image signal of the white reference document; and detecting the highest value of the white reference signal output by the image sensor, and determining the detected highest value as the predetermined reference value. The image reading device according to claim 1, further comprising: a maximum value detection unit that: 3. An image reading apparatus which irradiates light from a light source onto a document and outputs an image of the document as a binary image based on reflected light from the document, wherein the document receives the reflected light from the document. An image sensor that outputs an image signal of the following; a storage unit that stores in advance a reference value used when binarizing the image signal and a rate of change in the amount of light emitted from the light source; and a storage unit that is stored in the storage unit in advance. A / D which binarizes the image signal output by the image sensor based on a reference value obtained by correcting the reference value based on the change rate of the light amount stored in the storage unit in advance, and outputs the image signal as the binary image.
An image reading device, comprising: a conversion unit. 4. An image reading apparatus which irradiates light from a light source onto a document and outputs an image of the document as a binary image based on reflected light from the document, wherein the document receives the reflected light from the document. An image sensor that outputs an image signal of: a storage unit that stores in advance a reference value used when binarizing the image signal and a rate of change in the amount of light emitted by the light source; A reference value setting unit that reads a change rate from the storage unit and corrects the reference value based on the change rate of the light amount and outputs the reference value as a reference value; and the image sensor based on the reference value output by the reference value setting unit. An A / D conversion unit that binarizes the image signal output by the A / D converter and outputs the binarized image signal as the binary image. 5. A method of irradiating a white white reference original with light from the light source and receiving reflected light from the white reference original before receiving the reflected light from the original and outputting the image signal. The image sensor that outputs a white reference signal that is an image signal of the white reference document; and a storage unit that detects a maximum value of the white reference signal output by the image sensor and uses the detected maximum value as the reference value. The image reading apparatus according to claim 3, further comprising: a maximum value detection unit that stores the maximum value in the image reading unit. 6. The change rate of the light amount is a first change rate of the light amount based on deterioration of the light source due to aging, and a second change of the light amount based on a temperature of the light source due to heat generated by the light source. Claim 1, characterized in that:
6. The image reading device according to 2, 3, 4, or 5. 7. The image reading apparatus according to claim 1, wherein the first rate of change of the light amount is first determined by the maximum value detection unit after detecting the maximum value of the white reference signal and storing the same in the storage unit as the reference value. When reading the original, the light source is turned on in order to generate light to irradiate the original, and the amount of light of the light source is used as a reference, and the light source is determined according to the total lighting time from when the light is turned on. The image reading device according to claim 6, wherein 8. The second rate of change of the light amount is a light amount of the light source when the light source is turned on to generate light for irradiating the document when the image sensor outputs the image signal. The image reading device according to claim 6, wherein the image reading device is determined based on a lighting time from when the light is turned on based on a reference. 9. The method according to claim 6, wherein the reference value is a value obtained by multiplying the reference value, the first change rate of the light quantity, and the second change rate of the light quantity. An image reading device according to claim 1.