JP2002232653A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily perform highly accurate calibration with only one reference white plate. SOLUTION: A controlling part 117 moves an optical unit 108 to a prescribed reading operation start position, performs calibration by reading a horizontal reference white plate, also drives an optical unit drive motor 109 and sets the optical unit 108 at a prescribed position for reading an original from an ADF(automatic document feeder) 111. The original 101 fed at a constant speed by one piece at a time is made to pass through on the fixed optical unit 108 at a constant speed to be ejected to a prescribed paper ejecting opening. The optical unit 108 reads the entire image of the original 101 by generating image data in a horizontal scanning direction in every line of the original 101 made to move at the constant speed in a vertical scanning direction. When the controlling part 117 finishes reading one original, the controlling part 117 drives the motor 109 to set the optical unit 108 again at the prescribed position for reading an original from the ADF 111 and starts to feed the next original.

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 a flatbed type image scanner using a line sensor which has a sheet feed function and continuously reads an original. The present invention relates to a multifunction printer having an image scanner and an image scanner unit.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing the structure of a conventional image reading apparatus such as an image scanner.
Reference numeral 1 denotes a document, reference numeral 102 denotes a transparent document table using glass or the like for setting the document 101, reference numeral 103 denotes a light source for irradiating the document 101, reference numeral 104 denotes a reflection mirror, reference numeral 105 denotes a condenser lens, and reference numeral 106 denotes received light. And a photoelectric conversion circuit such as a CCD, which is arranged in the main scanning direction for converting the electric signal into an electric signal corresponding to the intensity. 107 is an image data generator for generating image data from the electric signal output from the photoelectric conversion circuit 106. Department.

Reference numeral 108 denotes a light source 103 and a reflection mirror 1
An optical unit 104 including a condenser lens 105, a photoelectric conversion circuit 106, an optical unit driving motor 109 for moving the optical unit 108 in the sub-scanning direction of the document 101, and an optical unit 108 capable of starting image reading A home position sensor 111 for detecting that the document is at a proper position (home position) is an automatic document feeder (ADF) 111 for automatically feeding a document in order to continuously read a plurality of documents.

Reference numeral 112 denotes an ADF drive motor for transporting the document 101 set on the ADF, 113 a document presence / absence detection sensor for detecting whether a document is set on the ADF, and 114 a reading operation by the ADF. A top sensor for detecting the leading edge and the trailing edge of the document being conveyed to determine the presence or absence of the document being read,
Reference numeral 15 denotes a horizontal reference white plate for detecting the intensity of light input to the photoelectric conversion circuit when reading a document set on the document table, and is disposed in the main scanning direction on the back side of the document table at the home position. I have.

Reference numeral 116 denotes a vertical reference white plate for detecting the intensity of light input to the photoelectric conversion circuit when the ADF is used, and is disposed on the back side of the document table outside the image reading range in the sub-scanning direction. Have been. Reference numeral 117 denotes a controller for controlling the entire image reading apparatus including the ADF 111.

[0006] The controller 117 in the image reading apparatus
Upon receiving an “image reading start” signal sent from an external host computer (not shown), the home position sensor 110 determines that the optical unit 108 is at a predetermined reading operation start position (home position).
Starts the image reading operation (when the optical unit 108 is not at the predetermined position,
Reference numeral 17 drives the optical unit drive motor 109 to set the optical unit 108 to the home position. ).

The controller unit 117 turns on the light source 103, and the light source 103 irradiates the horizontal reference white plate 115 with light. The light reflected by the horizontal reference white plate 115 is reflected by the reflection mirror 1.
After passing through 04, an image is formed by the condenser lens 105 and then enters the photoelectric conversion circuit 106. The light incident on the photoelectric conversion circuit 106 is converted into an electric signal corresponding to the intensity of the light, and is transmitted to the image data generation unit 107. Image data generator 10
In step 7, image data is generated at the time of reading a subsequent document using the level of the electric signal at this time as a reference white plate.

The operation of reading the reference white plate and determining the electric signal level of the reference white is hereinafter referred to as calibration. Next, the controller unit 117 drives the optical unit drive motor 109 to move the optical unit 108 at a constant speed in the sub-scanning direction. A light source 103 irradiates light to a document 101 set on a document table 102. The light reflected by the original 101 passes through a reflection mirror 104, is focused by a condenser lens 105, and then enters a photoelectric conversion circuit 106. Light incident on the photoelectric conversion circuit 106 is converted into an electric signal corresponding to the intensity of the light, and is converted into an image data generation unit 107.
Sent to

The image data generation unit 107 generates image data corresponding to one line in the main scanning direction of the document 101 based on the electric signal. Optical unit 10
8 while moving the document 8 at a constant speed in the sub-scanning direction.
An image of the entire document 101 is read by generating image data for each line of one main scanning direction. The image data generated by the image data generating unit 107 is sequentially transmitted to a host computer (not shown) via the controller 117.

Next, a case where a plurality of originals are continuously read using the ADF will be described. Controller unit 11
7 fixes the optical unit 108 at a predetermined position and performs calibration using the vertical reference white plate 116. As shown in FIG. 4, the vertical reference white plate 116 is arranged outside the image reading area of the document table 102 in the sub-scanning direction. Therefore, in the image data generation unit 107, the photoelectric conversion circuit 10
Calibration is performed using the electric signal of the vertical reference white plate 116 among the electric signals for one line in the main scanning direction input from 6.

When the calibration is completed, the controller 117 drives the ADF drive motor 112 to
The document 101 set on the DF 111 is transported one by one at a constant speed. The original 101 is fixed on an optical unit 108.
The paper passes through the upper portion at a constant speed and is discharged to a predetermined discharge port. The optical unit 108 reads an image of the entire document 101 by generating image data for each line in the main scanning direction of the document 101 moving at a constant speed in the sub-scanning direction.

When the reading of one document is completed, the controller 117 starts feeding the next document, and performs calibration with the vertical reference white plate 116 before the next document reaches the optical unit 108. The reason why the calibration is performed for each sheet is to correct the influence because the light amount of the light source 103 decreases due to the temperature rise mainly due to the heat generation of the light source 103 itself.

[0013]

However, in the above conventional example, the reference white plate is an automatic document feeder (ADF).
Two plates are required: a vertical reference white plate for use and a horizontal reference white plate for reading a document set on a document table.

Further, the light amount of the light source is smaller at the end portion than in the central image reading region. In addition, since the amount of change in the amount of light due to a rise in temperature is also different, it is very difficult to detect the amount of light in the central image reading area with high accuracy by calibration using the vertical reference white plate at the end of the document table. there were.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an image reading apparatus capable of easily performing high-accuracy calibration with only one reference white plate. Is to provide.

[0016]

According to the present invention, in order to achieve the above object, an invention according to claim 1 comprises: a platen; a light source for illuminating a document image on the platen; Photoelectric conversion means for receiving reflected light in the main scanning direction from a document image and converting the reflected light into an electric signal; document conveyance means for conveying the document image in the sub-scanning direction;
A sheet feeding unit for continuously feeding sheets one by one, a moving unit for moving the light source and the photoelectric conversion unit in the sub-scanning direction, and the light source and the photoelectric conversion unit in a state where a document is fixed on the platen. A first reading operation for reading a document by moving the document in the sub-scanning direction, and transporting the document image in the sub-scanning direction with the light source and the photoelectric conversion unit fixed at a predetermined position in the reading area of the document, and transporting the document. Reading means capable of performing two types of image reading operations of a second reading operation for reading;
A white plate long in the main scanning direction for detecting a reference white level disposed outside the reading area of the document, wherein when reading in the second image reading operation, And moving the light source and the photoelectric conversion means to detect a reference white level.

Further, the invention described in claim 2 is the first invention.
In the invention described in the above, when continuously reading a plurality of originals in the second image reading operation, the light source and the photoelectric conversion means is moved to the white plate between the originals every time the specified number of readings, It is characterized by detecting a reference white level.

Further, the invention according to claim 3 provides the invention according to claim 1.
In the invention described in the above, when reading a plurality of documents continuously in the second image reading operation, the light source and the photoelectric conversion means are moved to the white surface plate between the documents at regular time intervals, and It is characterized by detecting a white level.

According to the present invention, an automatic document feeder (AD)
F) By periodically moving the optical unit during use and performing calibration using the horizontal reference white plate, it is possible to perform highly accurate calibration when using the ADF with an inexpensive configuration that does not use the vertical reference white plate. .

[0020]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the image scanner when reading an ADF image according to the present embodiment. FIG. 2 is a cross-sectional view of the image scanner during calibration according to the present embodiment. Since the basic configuration and operation of the image scanner are the same as those described in the related art, the description of the overlapping parts will be omitted. Also, the numbers of the respective parts used in the figures are the same.

The operation of continuously reading a plurality of documents using the ADF will be described. First, similarly to the operation of reading an original set on the original platen, the controller 117
The optical unit 108 moves to a predetermined reading operation start position (home position) and performs calibration by reading the horizontal reference white plate 115. The controller unit 117 drives the optical unit drive motor 109 to set the optical unit 108 at a predetermined position for reading a document from the ADF 111.

Next, the controller 117 drives the ADF drive motor 112 to convey the documents 101 set on the ADF 111 one by one at a constant speed. The document 101 passes over the fixed optical unit 108 at a constant speed and is discharged to a predetermined discharge port. The optical unit 108 reads an image of the entire document 101 by generating image data for each line in the main scanning direction of the document 101 moving at a constant speed in the sub-scanning direction.

When reading of one document is completed, the controller unit 117 moves the optical unit 108 to the home position and performs calibration by reading the horizontal reference white board 115. When the calibration is completed, the controller unit 117 drives the optical unit drive motor 109 to cause the optical unit 108 to return to the ADF 11.
The original is set at a predetermined position for reading the original, and the ADF starts feeding the next original. Repeat the above operation,
A continuous image reading operation is performed.

In the above description, the calibration is performed for each sheet. However, the calibration may be performed for each job with several sheets as one job. Also,
The present invention can also be used for, for example, a multifunction printer or the like having an image reading device.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIGS. Since the operation is basically the same as that of the first embodiment, only the parts different from the first embodiment will be described.

In the operation of continuously reading a plurality of originals by using the ADF 111, the controller 117 performs the operation after the home position calibration is completed.
Timer (not shown) built in controller unit 117
Start. ADF 111 for the optical unit 108
The original is set at a predetermined position where the original is read, and the ADF is driven to perform image reading. When the timer reaches a predetermined time, the controller unit 117 performs calibration by moving the optical unit 108 to the home position and reading the horizontal reference white board 115.
If the image reading operation is being performed when the timer reaches the specified time, the calibration is performed after the reading of the page is completed.

[0027]

As described above, according to the present invention, an original image is conveyed in the sub-scanning direction while the light source and the photoelectric conversion means are fixed at predetermined positions in the original reading area, and the original is read. When reading is performed in the second image reading operation, the light source and the photoelectric conversion unit are moved to a long white plate in the main scanning direction before the reading operation is started, and Since the white level is detected, even a flatbed type image scanner equipped with an ADF can easily perform high-precision calibration with only one reference white plate, thereby simplifying the structure and reducing costs. Become.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image scanner when reading an image using an ADF according to first and second embodiments of the present invention.

FIG. 2 is a schematic diagram of an image scanner at the time of calibration according to the first and second embodiments of the present invention.

FIG. 3 is a schematic diagram of calibration between image pages according to the first and second embodiments of the present invention.

FIG. 4 is a schematic sectional view of a conventional image scanner.

[Explanation of symbols]

 101 Document 102 Document Plate 103 Light Source 104 Reflecting Mirror 105 Condensing Lens 106 CCD 107 Image Data Generator 108 Optical Unit 109 Motor 110 Home Position Sensor 111 Automatic Document Feeder (ADF) 112 ADF Drive Motor 113 Paper Presence Sensor 114 Top Sensor 115 Horizontal reference white plate 116 Vertical reference white plate 117 Controller

Claims (3)

[Claims] 1. A document table, a light source for illuminating a document image on the document table, photoelectric conversion means for receiving reflected light in a main scanning direction from the document image and converting the reflected light into an electric signal, Document feeding means for feeding in the sub-scanning direction, sheet feeding means for continuously feeding a plurality of documents one by one to the document feeding means, and moving means for moving the light source and the photoelectric conversion means in the sub-scanning direction; A first reading operation of reading the original by moving the light source and the photoelectric conversion unit in the sub-scanning direction while the original is fixed on the original platen, and reading the light source and the photoelectric conversion unit to an original reading area; A reading unit capable of performing two types of image reading operations of a second reading operation of transporting the document image in the sub-scanning direction and reading the document in a state where the document image is fixed at a predetermined position inside the document; Detects the reference white level located at A white surface plate that is long in the main scanning direction for reading, and when reading is performed in the second image reading operation, the light source and the photoelectric conversion unit are moved to the white surface plate before the reading operation starts, and a reference white level is set. An image reading device characterized by detecting the following. 2. When reading a plurality of originals continuously in the second image reading operation, the light source and the photoelectric conversion means are moved to the white surface plate between the originals each time a prescribed number of originals are read. The image reading apparatus according to claim 1, wherein a white level is detected. 3. When reading a plurality of documents continuously in the second image reading operation, the light source and the photoelectric conversion unit are moved to the white surface plate between the documents at regular time intervals,
The image reading apparatus according to claim 1, wherein a reference white level is detected.