JPH06205173A - Picture reader - Google Patents

Abstract

PURPOSE:To quicken continuous reading speed by avoiding useless carriage feeding even when a size of an original placed on an original platen glass differs or the placing position of an original is deviated due to mis-feeding. CONSTITUTION:At application of power, a carriage 6 is moved up to a read start position and an original 1 is carried up to a prescribed position on an original platen glass 11 from an original placing plate 14. When a light source 2 is lighted, picture data of the original 1 are sequentially read while repeating of reading operation of picture data by one line located in the main scanning direction of the original 1 by each light receiving element of an image sensor 4 and moving operation of the carriage 6 in the subscanning direction by one line with a drive motor 7, and when an original detector 101 detects a tail end of the original 1 being a read end position, the picture read operation is stopped and the drive motor 7 is reversed to restore the carriage 6 up to the read start position immediately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for reading original image data, such as a facsimile, a digital copying machine, a scanner, etc., which is equipped with an automatic document feeder.

[0002]

2. Description of the Related Art In recent years, an image reading apparatus, such as a digital copying machine, which digitally reads and reproduces an original, is equipped with an automatic document feeder (ADF) and is generally used. It was

In such an automatic document feeder, a document size detection sensor for accurately reading the size of the document is installed on the lower surface of the document or on the paper feed section of the automatic document feeder.

FIG. 5 shows the structure of a conventional image reading apparatus. Reference numeral 1 is a document, 2 is a light source such as a fluorescent lamp, 3 is a lens, and 4 is a light source.
Is a self-scanning image sensor such as a line CCD solid-state imaging device in which light receiving elements (not shown) are arranged in a line in the main scanning direction of the original 1, 5 is a reflecting mirror, 6 is a light source 2, a lens 3, an image A carriage that holds an optical system composed of a sensor 4 and a reflection mirror 5, and this carriage 6 is the original 1
Can be moved in the sub-scanning direction (direction of arrow A in the figure). Reference numeral 7 is a drive motor having a drive pulley 8 attached to a rotary shaft. When the drive motor 7 rotates, the carriage 6 is driven by a drive wire 10 stretched between the drive pulley 8 and a driven pulley 9.
Moves in the sub-scanning direction of the document 1.

Reference numeral 11 is a platen glass, and 12 is an automatic document feeder.
(ADF), 13 is a conveyor belt of the automatic document feeder 12 that conveys the original 1, 14 is an original loading table for loading a plurality of originals 1,
Reference numeral 15 is a document size detector in which the sensors 15a to 15d are aligned in the main scanning direction of the document 1 (see FIG. 6), and 16 is a document deviation detector in which the sensors 16a to 16c are aligned in the sub scanning direction of the document 1 (see FIG. 6). 6) and 17 are document sensors arranged in the same direction as the document shift detector 16.

In the conventional example thus constructed, when the power is turned on, first, the drive motor 7 rotates and the carriage 6 moves to the reading start position. Next, the conveyance belt 13 and the like are driven, so that the original 1 is transferred from the original stack 14 to the original glass
It is conveyed in the arrow direction in FIG. 6 to a predetermined position of 11.

At this time, the width of the document 1 is determined by the document size detector.
If it is detected by 15, the signal output of each sensor 15a to 15d differs depending on the size of the original 1 as shown in FIG. 7, so that it is possible to detect which size of the original 1 is B5 to A3. .

Further, the passage time of the front end of the original 1 is detected by the original misregistration detector 16, and the time for the original 1 to pass between the sensor 16a and the sensor 16b is T ₁ , and between the sensors 16b and 16c. If the time when the document 1 passes through T is the same as T ₁ as shown in FIG. 8A, it is determined that the document 1 is normally conveyed by the automatic document feeder 12. However, the time T ₁ during which the document 1 passes between the sensor 16a and the sensor 16b and the sensor 16b
The time T ₂ required for the document 1 to pass between the sensor 16c and the sensor 16c is shown in FIG.
As shown in (b), if the original 1 is different, the original 1 is fed by the automatic original feeder 12
If the deviation amount is smaller than a predetermined value, the deviation amount is converted into a distance when the deviation amount is detected from the passage time of the document 1 detected by the sensors 16a to 16c. The carriage 6 feed amount, that is, the original 1
The folding position of the carriage 6, which is the reading end position of the image data, is adjusted, and if the deviation amount is larger than a predetermined value, the image reading operation is stopped.

When the document 1 is placed on the document table glass 11, the light source 2 is turned on to illuminate the surface of the document 1 and the image sensor 4 is driven. Then, the light reflected on the surface of the original 1 is condensed by the lens 3 and then is incident on the light receiving portion of the image sensor 4, and the image data for one line (each pixel ) Is converted into an image signal proportional to black and white gradation by each light receiving element of the image sensor 4 and output, and then the carriage 6 is moved by one line in the sub-scanning direction by the drive motor 7. Such an operation is sequentially repeated until the reading end position of the size of the original 1 detected by the original size detector 15 is read, and when the carriage 6 reaches the reading end position after all the image data of the original 1 is read. The carriage 6 is driven to reverse and the carriage 6 is returned to the reading start position.

As described above, in the conventional image reading apparatus, the document size detector 15 detects the size of the document 1 and a feed error, and the document misalignment detector 16 places the document placed on the platen glass 11. Detecting the deviation amount of 1
The folding-back position of the carriage 6 which is the reading end position of the image data is determined.

[0011]

However, the position of the document 1 on the platen glass 11 is displaced from a predetermined position due to a feed error of the automatic document feeder 12, or the size of the document 1 in the sub scanning direction is the document size. Even if the standard size detected by the detector 15 is longer than the specified size in the sub-scanning direction, the carriage 6 will not detect the original size detector 15
Since only the specified distance corresponding to the size of the original document 1 detected by the above-mentioned method is sent, there is a problem in that a reading error occurs in which the image data of the original document 1 in a portion outside the moving distance of the carriage 6 cannot be read.

In order to solve this problem, some sensors are provided to detect the presence / absence of the document 1 in the sub-scanning direction, but there is a problem in that the manufacturing cost is high, and these sensors are used. As long as the interval is not so narrow, the above-mentioned reading error occurs, so that the carriage 6 must be additionally fed to the position of the sensor which is one sensor ahead of the sensor detecting the document 1. When continuously reading the image data, the continuous reading speed of the image data is reduced by the amount of the extra carriage 6.

The present invention has been made in view of such a problem, and detects the presence or absence of an original document on the original platen glass in the sub-scanning direction to mix original documents having different lengths or cause misfeeds. Even in such a case, it is an object of the present invention to provide an image reading apparatus which can increase the continuous reading speed and reduce the manufacturing cost by eliminating unnecessary carriage feeding.

[0014]

According to the present invention, light from a light source reflected by a document placed on a document table glass is made incident on an image sensor, and image data in the main scanning direction of the document is read by the image sensor. Optical means for moving the image sensor, moving means for moving the optical means by one line in the sub-scanning direction each time the image sensor reads image data for one line of the original, and moving when the optical means detects the rear end of the original. And a document detection unit that immediately returns the unit to the document reading start position.

[0015]

According to the present invention, the operation of reading the image data is performed from the reading start position until the trailing edge of the document at the reading end position is detected by the document detector. Even if the original is placed at a position displaced from the position in the sub-scanning direction, or the size of the document in the sub-scanning direction is longer than the specified size in the sub-scanning direction of standard size paper,
Within the range where the image can be read by the carriage, all the image data of the original can be surely read, the re-reading work of the image data of the original is reduced, and the continuous reading speed becomes high.

When the document detector detects the reading end position, the carriage is immediately returned to the reading start position, so that the carriage does not move excessively and the continuous reading speed becomes higher.

Further, if the image reading device or the automatic document feeding device is stopped when it is detected that the document is out of the image readable range by the carriage, the re-reading operation of the document image data is reduced. , Continuous reading speed becomes high.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a structure of an embodiment of the present invention, and FIG. 2 shows a structure of a carriage in an embodiment of the present invention. The same reference numerals as those in FIGS. The reference numeral 101 designates a manuscript detector comprising a light emitting element 102, a spectral prism 103 and a light receiving element 104. The manuscript detector 101 has an optical axis which corresponds to that of the image sensor 4 as shown in FIG. It is arranged so as to be parallel to each other and to face the reflection mirror 5.

In this embodiment thus constructed, when the power is turned on, the drive motor 7 rotates and the carriage 6
When the document is moved to the reading start position, the conveyor belt 13 and the like are driven, and the document 1 is conveyed from the document stacking table 14 in the direction of the arrow in FIG. 6 and placed on the document table glass 11 at a predetermined position. . Then, the light source 2 is turned on, and the original table glass is turned on.
Since the surface of the original 1 above 11 is illuminated and the image sensor 4 is driven, the light reflected by the surface of the original 1 is condensed by the lens 3 and enters the light receiving portion of the image sensor 4. .

Then, one line of image data in which each light receiving element of the image sensor 4 is positioned in the main scanning direction of the original 1
While repeating the image reading operation of converting (each pixel) into an image signal proportional to the black and white gradation and outputting the image signal and the carriage moving operation of moving the carriage 6 by one line in the sub-scanning direction by the drive motor 7, The image data of 1 is sequentially read.

When the document detector 101 detects the rear end of the document 1 at the reading end position, for example, from the difference between the color of the document 1 and the color of the surface of the conveyor belt 13 (see FIG. 3), the image sensor 4 is detected. While the image reading operation by the is stopped, the drive motor 7 is reversely driven, and the carriage 6 returns to the reading start position. After that, every time the original 1 is placed on the original glass 11 at a predetermined position, the above operation is repeated.

Even when the document 1 is placed on the platen glass 11 at a position deviated from a predetermined position, the image data of the document 1 is repeated by repeating the image reading operation and the carriage moving operation from the reading start position. When the document detector 101 detects the rear end of the document 1 at the reading end position, the image reading operation by the image sensor 4 is stopped, and the drive motor 7 is reversely driven to read the carriage 6. Return to the start position. After that, every time the original 1 is placed on the original glass 11 at a predetermined position, the above operation is repeated.

As described above, according to the present embodiment, even if the document 1 is placed on the document table glass 11 at a position deviated from the predetermined position in the sub-scanning direction, the reading start position is changed to the reading end position. When the document detector 101 detects the rear end of the document 1 and the image data of the document 1 is read, and when the document detector 101 detects the reading end position,
The carriage 6 is immediately returned to the reading start position.

Even if the size of the original document 1 in the sub-scanning direction is longer than the specified size of the standard size paper in the sub-scanning direction, the rear end of the original document 1 from the reading start position to the reading end position is detected. The image data of the original 1 is read until the device 101 detects it, and when the document detector 101 detects the reading end position, the carriage 6 is immediately returned to the reading start position.

In the present embodiment, when the document 1 is placed on the platen glass 11 at a position deviated from a predetermined position in the sub-scanning direction, the document from the reading start position to the reading end position is read. The example in which the reading operation of the image data of the misaligned portion and the original 1 is performed until the original detector 101 detects the trailing edge of the original 1 has been described, but the original detector 101 does not detect the original 1 at the reading start position. Occasionally, a process of deleting image data of a misaligned portion read from the reading start position until the document detector 101 detects the front edge of the document 1 is performed,
Until the document detector 101 detects the front end of the document 1 from the reading start position, the image data of the document 1 may not be read and only the image data of the document 1 may be read.

When the document detector 101 does not detect the document 1 at the reading start position, the carriage 6 may be fast-forwarded from the reading start position until the document detector 101 detects the front end of the document 1.

Further, in the present embodiment, an example has been described in which the light from the light emitting element 102 is applied to the original 1 to detect the reading start position and the reading end position of the original 1, but the light is reflected on the surface of the original 1. By detecting the light of the light source 2 by the light receiving element 104 to detect the presence or absence of the document 1, the document detector 101 can be manufactured in a small size, light weight and at low cost.

Further, in the present embodiment, the image reading apparatus with the automatic document feeder is described as an example, but the document table glass
Even if the document 1 manually placed at a predetermined position above 11 is displaced in the sub-scanning direction when pressed by the automatic document feeder 12 or a pressure plate (not shown), the reading start position is changed to the reading end position. The image data of the document 1 can be read until the document detector 101 detects the trailing edge of the document 1.

[0030]

As described above, according to the present invention,
Since the image data reading operation is performed from the reading start position until the document detector detects the trailing edge of the document at the reading end position, the document is deviated from the predetermined position on the platen glass in the sub-scanning direction. Even if the document is placed in a position or the size of the document in the sub-scanning direction is longer than the specified size of the standard size paper in the sub-scanning direction, all the image data of the document can be guaranteed within the image readable range of the carriage. The effect of being able to read the image is reduced, and the work of re-reading the image data of the original is reduced,
This has the effect of increasing the continuous reading speed.

Further, when the document detector detects the reading end position, the carriage is immediately returned to the reading start position, so that the carriage does not move excessively and the continuous reading speed becomes higher.

Further, if the image reading device or the automatic document feeding device is stopped when it is detected that the document is out of the image readable range by the carriage, the work of re-reading the document image data is reduced. The effect of increasing the continuous reading speed is achieved.

Further, since there is only one sensor for detecting the presence / absence of a document in the sub-scanning direction, and a means for calculating the position of the document is not required, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a plan view of a carriage equipped with a document detector according to an embodiment of the present invention.

FIG. 3 is a diagram showing a state in which a trailing edge of a document is detected by a document detector according to an embodiment of the present invention.

FIG. 4A is a timing chart when a document is normally conveyed by an automatic document feeder in one embodiment of the present invention, and FIG. 4B is a timing chart when the document is automatically conveyed in one embodiment of the present invention. 6 is a timing chart when a feed error occurs by the device.

FIG. 5 is a side view showing an outline of a configuration of a conventional image reading device.

FIG. 6 is a layout diagram of sensors in a conventional image reading apparatus.

FIG. 7 is an example of detecting a document size in a conventional image reading apparatus.

FIG. 8A is a timing chart when a document is normally conveyed by the automatic document feeder in the conventional image reading apparatus, and FIG. 8B is a timing chart when the document is conveyed by the automatic document feeder in the conventional image reading apparatus. It is a timing chart at the time of a feed mistake.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original document, 2 ... Light source (optical means), 3 ... Lens (optical means), 4 ... Image sensor, 5 ... Reflection mirror (optical means), 6 ... Carriage (moving means), 7 ... Drive motor, 8 ... Drive Pulley 9 Driven pulley 10 Drive wire 11 Platen glass 12 Automatic document feeder
(ADF), 13 ... Conveyor belt, 14 ... Original stacking table, 15
... Document size detector, 15a-15d, 16a-16c ... Sensor,
16 ... Document misalignment detector, 17 ... Document sensor, 101 ... Document detector.

Claims (1)

[Claims] 1. Optical means for causing light of a light source reflected by a document placed on a platen glass to be incident on an image sensor, and causing the image sensor to read image data of the document in a main scanning direction, Every time the image sensor reads the image data of one line of the original, the moving unit moves the optical unit by one line in the sub-scanning direction; and when the optical unit detects the rear end of the original, the moving unit moves the image. An image reading apparatus comprising: a document detecting unit that immediately returns the unit to a document reading start position.