JP2000113162A - Device and method for reading image and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read out images by exactly moving an image sensor to a reading start position by detecting a reference position even without the home position sensor of the image sensor concerning an image reader for reading the images of an original through the image sensor for each line. SOLUTION: An image sensor 1 is scanned in the main and the sub directions of the original, and the images of the original are read for each line. In that case, a black area 3 and a white area 4 on glass 2 for reading the original are detected by the image sensor 1, the reference position of the image sensor 1 is determined by these detecting signals, and the read of images is started. Besides, at the time of position initializing processing to the image sensor when a power source is turned on, the black area 3 and white area 4 are detected while defining all the main scanning areas as an object. After the images are read out, any arbitrary main scanning areas are selected and these areas 3 and 4 are detected.

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, an image reading method, and a storage medium for reading an image of an original document line by line using an image sensor.

[0002]

2. Description of the Related Art Conventionally, an image in which a document is read by an image sensor and converted into an electric image signal, and the analog image signal is converted into a digital signal by an A / D converter and transferred to an external device. Reading devices are known.

In such an image reading apparatus, when an image sensor for scanning a document is moved to a reading start position in order to determine a reading start position of an image,
A home position sensor that detects the position of the image sensor by turning on and off the output using a photodiode or the like is provided, thereby determining a reading start position.

In recent years, products that detect the reading start position without using the above-mentioned photodiode or the like have come to be seen from the viewpoint of cost reduction of such a scanner. In such products,
A specific pattern is provided at the reading start position of the scanner, and the reference position is determined based on the coincidence of the pattern.

[0005]

However, in the conventional low-cost scanner as described above, before providing a complicated pattern, the reference position is set based on only a simple black area in order to further reduce the cost. Must be detected and judged. In many cases, the performance of the processing unit (CPU) that performs the detection is also low, and it is impossible to judge pattern data coincidence at high speed. In addition, there is a limit in executing complicated processing. Therefore, there is a problem that erroneous detection occurs with a high probability depending on the document on the document table, and the image sensor may stop at a position other than the reference position.

In view of the above problems, an object of the present invention is to provide an inexpensive version without a home position sensor and without providing a complicated pattern near the reference position to determine the reference position. An image reading apparatus capable of detecting the reference position so that the image sensor does not return to the reference position, reducing erroneous detection of the reading start position, and accurately detecting the start position;
An object of the present invention is to provide an image reading method and a storage medium.

[0007]

An image reading apparatus, an image reading method, and a storage medium according to the present invention are configured as follows.

(1) An image reading apparatus for reading an image of a document line by line by conveying an image sensor in a sub-scanning direction, and detecting means for detecting a predetermined mark for reading an image by the image sensor; Control means for determining a reference position of the image sensor based on the detected mark and starting reading of an image, wherein the detection means targets the entire main scanning area before reading the image by the image sensor when power is turned on. A mark is detected, and after the image is read out by the image sensor, an arbitrary main scanning area is selected to detect the mark.

(2) In the configuration of (1), the mark is provided at or near the reading start position of the image sensor.

(3) In the configuration of the above (1) or (2), an A / D converter for converting an analog image signal read by the image sensor into a digital image signal;
There is provided a transfer means for transferring the converted digital image signal to an external device.

(4) In any one of the above constitutions (1) to (3), reading of an image is started from a predetermined position based on the reference position.

(5) In any one of the above constitutions (1) to (4), after the reference position of the image sensor is determined and the image sensor is moved to a predetermined position, the reference position is set within a predetermined range in the sub-scanning direction. The entire area of the main scan is selected, the mark is detected again, the reference position is determined again according to the detected mark, and the image sensor is moved.

(6) An image reading method for conveying an image sensor in a sub-scanning direction and reading an image of a document line by line, wherein a predetermined mark provided for image reading by the image sensor is detected, While determining the reference position of the image sensor based on the detected mark and starting reading of the image, the detecting means targets the entire main scanning area before reading the image by the image sensor when power is turned on. A mark is detected, and after the image is read out by the image sensor, an arbitrary main scanning area is selected to detect the mark.

(7) In the configuration of (6), the mark is provided at or near the reading start position of the image sensor.

(8) In the configuration of (6) or (7), reading of an image is started from a predetermined position based on the reference position.

(9) In any one of the above constitutions (6) to (8), after the reference position of the image sensor is determined and the image sensor is moved to a predetermined position, the reference position is set within a predetermined range in the sub-scanning direction. The entire area of the main scan is selected, the mark is detected again, the reference position is determined again according to the detected mark, and the image sensor is moved.

(10) A storage medium storing a program for reading an image of a document line by line by conveying the image sensor in the sub-scanning direction, and detecting a predetermined mark for reading the image of the image sensor. Then, the reference position of the image sensor is determined based on the detected mark, and reading of an image is started, and before the image is read by the image sensor at power-on, the mark is detected for the entire main scanning area, After the image was read by the image sensor, a program for selecting an arbitrary main scanning area and detecting the mark was stored.

(11) In the configuration of (10), a program for converting an analog image signal read by the image sensor into a digital image signal and transferring the converted digital image signal to an external device is stored.

(12) In the configuration of (10) or (11), a program for starting reading of an image from a predetermined position based on the reference position is stored.

(13) In any one of the above constitutions (10) to (12), after determining the reference position of the image sensor and moving the image sensor to a predetermined position, the image sensor is moved within a predetermined range in the sub-scanning direction. The entire area of the main scan was selected, the mark was detected again, and a program for determining the reference position again according to the detected mark and moving the image sensor was stored.

[0021]

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

[Embodiment 1] FIG. 1 is a diagram showing the internal structure of a document image reading apparatus according to an embodiment of the present invention, and shows the structure of a reference position detecting unit.

In FIG. 1, reference numeral 1 denotes a contact-type contact image sensor (hereinafter referred to as CIS), which comprises a photodiode, a selfoc lens, an LED array, and a contact glass (not shown). This C
An original table glass 2 is arranged on the IS 1 and is moved line by line by a drive motor (not shown) in a scanning direction (sub-scanning direction) shown in the figure to read an image.

Further, a black area 3 and a white area 4 are provided on the original surface side of the original platen glass 2 on the minus side in the sub-scanning direction from the reading start position B at which reading is started. The black area 3 and the white area 4 are used for detecting the reading start position B of the document and are also required for performing the calibration process. The detection of the reading start position and the calibration processing are both performed by reading this area from the CIS 1. Also, the home position A is set to CIS before reading is actually started.
1 is a standby position.

FIG. 2 is a block diagram showing the configuration of the control circuit in this embodiment. Hereinafter, the circuit operation of the present invention will be described with reference to FIG.

In FIG. 2, reference numeral 101 denotes the above-mentioned CIS (scan bar), which is a light source such as R (red), G (green),
The B (blue) LED 102 is also integrated, and this CI
While the S101 is being conveyed on the platen glass 2 in the scanning direction, the LED drive circuit 103 switches the LED 102 of each color for each line to light up.
It is possible to read RGB line sequential color images.

Reference numeral 104 denotes an amplifier (AMP) for amplifying the signal output from the CIS 101, and reference numeral 105 denotes an A / D converter for performing A / D conversion of the amplified output to obtain an 8-bit digital output, for example.

The shading RAM 106 stores the black area 3 and the white area 4 for the above-described calibration processing.
, And shading correction data obtained by arithmetically processing the data is stored. The shading correction circuit 107 performs shading correction of the image data read by the CIS 101 based on the data in the shading RAM 106. I do.

The peak detecting circuit 108 detects a peak value in the read image data line by line, and is used for detecting the reading start position B.

The gamma conversion circuit 109 performs gamma conversion of image data read in accordance with a gamma curve preset by a host computer described later.

The buffer RAM 110 is a memory for temporarily storing image data in order to match the timing of the actual reading operation with the communication with the host computer. The packing / buffer RAM control circuit 111
Are image output modes (binary, 4-bit multi-level, 8-bit multi-level, 24
After performing a packing process according to bit multi-values, a process of writing the data to the buffer RAM 110 and a process of transferring image data from the buffer RAM 110 to the interface circuit 112 and outputting the image data are performed.

The above-mentioned interface circuit (transfer means) 1
Numeral 12 receives a control signal and outputs an image signal between the image reading apparatus according to the present embodiment, such as a personal computer, and the external apparatus 113 serving as the above-described host apparatus (computer).

Reference numeral 115 denotes a CPU in the form of a microcomputer, for example, which has a ROM 115a storing a processing procedure and a working RAM 115b, and controls each section according to the procedure of a program stored in the ROM 115a.

Reference numeral 116 denotes, for example, a crystal oscillator, and a timing signal generation circuit 114 divides the output of the oscillator 116 in accordance with the setting of the CPU 115 to generate various timing signals serving as operation references.

In this embodiment, the black area 3 and the white area 4 shown in FIG. 1 are predetermined marks for reading an image of the CIS 101. The CPU 115 is configured to control the reference position of the CIS 101 to start reading of an image. Then, before the image is read out by the CIS 101 when the power is turned on (at the time of the position initialization process), the mark is detected for the entire main scanning area,
After the image is read by the CIS 101, an arbitrary main scanning area is selected to detect a mark.

FIG. 3 is a diagram showing a read area of the CIS 101 of this embodiment. Here, a dummy pixel area from the start point SP to the zero point in the main scanning direction, a home position HP detection area from the start point SP to the α point, and an effective pixel area from which an image is read thereafter are shown.

Next, with reference to the flowcharts of FIGS. 4 and 5, a description will be given of the processing operation at the time of initialization after power-on according to the present embodiment, that is, the detection processing of the reading start position B.

After the power is turned on, the image reading apparatus performs a home position detecting process after a series of initialization operations (initialization) is completed.

In the home position detection process, first, in step S1, a mode setting for detecting the boundary between the black area 3 and the white area 4 shown in FIG. 1 is performed. At this time,
The CPU 115 in FIG. 2 performs settings for the CIS 101 and the peak detection circuit 108, and also sets the lighting timing for the LED drive circuit 103 in the CPU 115. At this time, the area for detecting the boundary designates the entire main scanning area.
Here, the entire main scanning area refers to a range from the start point (SP) shown in FIG. 3 to an effective pixel area after the dummy pixel area and thereafter (from zero point). That is, it is an area of an effective range that can be read as a signal.

Next, in step S2, a threshold value for detecting the boundary between the black and white areas is determined. This is the CPU 115
The processing is determined within. Subsequently, in step S3, the G LED 10 based on the set lighting timing is set.
2 is turned on, and boundary detection is started.

At this time, first, the peak value is read from the peak detection circuit 108, and it is checked whether or not the level is within a range in which the black level is equal to or less than the threshold value of the black area 3 (step S4). If the peak value is at the black level, the process jumps to step S10 of the black and white boundary detection process. If the peak value is not the black level, the process proceeds to step S5. At this time, since the scan bar has not returned to the home position A for some reason, a setting to enter a return process for returning the scan bar to the home position is performed.

At this time, the CPU 115 sends a signal to a motor drive circuit (not shown) to start returning the scan bar (step S6). During the return of the scan bar, the CPU 115 receives the signal from the peak detection circuit 108 and monitors that the level reaches the black level (step S7).

The return of the above-mentioned scan bar is set, for example, so as to limit the feed amount of the maximum scan width A4 size. During the return, monitoring within this range is performed (step S8), and the above-mentioned specified feed amount is returned. Continue monitoring the black level within the range not exceeding.

If a black area can be detected, the process proceeds to step S9, where the CPU 115 stops driving the motor, immediately stops the return of the scan bar, and proceeds to the next process.

After the black level is detected, step S
At 10, a black and white boundary detection process for detecting a more accurate boundary is performed. At this time, first, a mode setting for the boundary detection is performed. Also in this case, the reading selection of the entire effective range shown in FIG. 3 is performed. Then, the CPU 115 sets the peak detection of the white level this time as the setting to the peak detection circuit 108, and the LED drive circuit 1 in the CPU 115.
Set the lighting timing to 03.

Next, in step S11, the CP
U115 sends a lighting signal to the LED drive circuit 113 to start peak detection. Then, in step S12, the sub-scanning maximum feed amount for detection is set (for example, in a range of 1 to 2 mm that is considered to reach the white area), and the movement of the scan bar is started (step S13).

Next, in step S14, it is checked whether the peak value has reached the white level. If the level has not reached, the feed amount specified in step S15 is checked, and if the level does not exceed the white level threshold range, the process of step S14 is repeated. If the peak value has reached the white level, the process proceeds to step S16, where C
PU 115 immediately stops the scan bar.

If the scan bar feed amount exceeds the set range in step S15, step S16
Then, stop the scan bar similarly. At this time, the CPU 115 sets an error flag in step S17 and notifies the external device 113 via the interface circuit 112 of a home position detection error.

Next, the CPU 115 turns off the LED 102 (step S18), and moves the scan bar to the home position A shown in FIG. 1 in step S19. Then, this position is stored as a reference position in a data storage unit (for example, in the RAM 115b of the CPU 115) (step S20), the motor is turned off (step S21), and the process is terminated. After the end, a standby state, which is a scan standby state, is set.

Scanning is possible from the above-mentioned standby state, and the scanning is started, and the scanning after the set number of lines is completed or the scanning is canceled, and the processing after image reading shown in the flowcharts of FIGS. Is started.

That is, when the task bar stops at the end of scanning, black area detection is set in step S31. Here, the area designated for detecting the black area is several points in the effective pixel area after the dummy area from the start point (SP) shown in FIG. 3, that is, between 0 point and α point shown in FIG. Indicates the range of the HP detection region.

The pixel area up to the α point is a portion where the document is not placed, and the reading range of the document image is actually from the α point. This is because if an entire valid image area is specified, it may be erroneously determined to be a black area depending on the original, so that it is a small number of pixels, and the detection accuracy is lowered, but it is taken as an area to avoid it. .

Next, in step S32, a threshold value for determining again as a black area is set, and the G LED 102 is set to L level.
It is driven by the ED drive circuit 103 to start detecting the black area 3 (step S33). Then, step S3
In step 4, a setting is made to enter a return process for returning the scan bar to the home position.

Next, the CPU 115 sends a motor drive signal to the motor, and starts moving the scan bar in the return direction (step S35). During the return of the scan bar, the CPU 115 inputs a signal from the peak detection circuit 108 and monitors that the level reaches the black level (step S36).

In the return of the scan bar, the feed amount of the scan width A4 size is set as a set value, and during return, the monitoring of the black level is continued within the range of the feed amount (step S37).

If a black area can be detected, the process proceeds to step S38, where the CPU 115 stops driving the motor and immediately stops the return of the scan bar.
Move to the next process. The CPU 115 also proceeds from step S37 to step S38 when the counting of the motor feed amount ends, and stops the motor drive signal.

Next, in step S39, in order to more accurately detect the reference position at the time of stopping the motor, the black-and-white boundary detection process is started again, and a white area is detected. At this time, the CPU 115 first sets a mode for boundary detection. In addition, as a setting for the peak detection circuit 108, a white level peak detection setting range is set to the entire effective area. In step S40, the maximum sub-scan feed amount for detection is set (for example, in the range of 1 to 2 mm), and the movement of the scan bar in the document scanning direction is started (step S40).
41).

Next, in step S42, it is checked whether the peak value has reached the white level. If the level has not reached, the feed amount specified in step S43 is checked. Step S
Repeat 42. If the peak value reaches the white level,
The process proceeds to step S44, and the CPU 115 immediately stops the scan bar.

If the feed amount of the scan bar exceeds the range also in step S43, the process proceeds to step S44, and the scan bar is similarly stopped. At this time,
The CPU 115 sets an error flag (step S4).
5) Informing the external device 113 via the interface circuit 112 as a home position detection error.

Next, the CPU 115 turns off the LED 102 (step S46), and moves the scan bar to the home position A shown in FIG. 1 in step S47. Then, this position is stored as a reference position in a data storage unit (for example, in the RAM 115b of the CPU 115) (step S48), the motor is turned off (step S49), and the process is terminated.

Thereafter, it is confirmed whether or not all the read image data has been sent to the external device 113 via the interface circuit 112 (step S50). Becomes

As described above, in the present embodiment, the initial reference position of the CIS 101 is detected in the entire area of the CIS 101 during the initial setting processing after the power is turned on, and a part of the CIS 101 is returned when returning after the image reading. And use it for detection.

For this reason, even in a low-cost scanner without a home position sensor and without providing a complicated pattern for determining the reference position near the reference position, the CIS 101 is prevented from returning to the reference position. The detection of the reference position can be performed quickly, the erroneous detection of the reading start position can be reduced, and the start position can be accurately detected.

The control processing shown in the flowcharts of FIGS. 4 to 7 is performed by the CPU 115 of FIG.
The program is executed according to the program stored in 15a. Further, the control processing program can be stored in a desired storage medium, and the processing operation can be performed by a computer.

[Other Embodiments] In the above embodiment,
Although the contact image sensor 101 is used as an image reading sensor, a sensor using a CCD image sensor is also an effective means.

After the reference position of the image sensor is determined and the image sensor is moved to a predetermined position, the entire area of the main scanning is selected within a predetermined range in the sub-scanning direction, and the mark is detected again. The reference position may be determined again according to the detected mark, and the image sensor may be moved.

[0067]

As described above, according to the present invention,
Even in a device without a home position sensor, after reading a document, the home position is detected using a part of the effective area of the sensor, thereby reducing erroneous detection of the reading start position and accurately detecting the position. become able to.

[Brief description of the drawings]

FIG. 1 is a diagram showing an internal configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing an electric circuit configuration of the embodiment.

FIG. 3 is an explanatory diagram showing a read area according to the embodiment;

FIG. 4 is a flowchart illustrating a processing operation at the time of initial setting according to the embodiment;

FIG. 5 is a flowchart illustrating a processing operation at the time of initial setting according to the embodiment;

FIG. 6 is a flowchart illustrating a processing operation after image reading according to the embodiment;

FIG. 7 is a flowchart illustrating a processing operation after image reading according to the embodiment;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 contact image sensor 2 platen glass 3 black area 4 white area 101 contact image sensor 102 LED 103 LED drive circuit 104 amplifier 105 A / D conversion circuit 106 shading RAM 107 shading correction circuit 108 peak detection circuit 109 gamma conversion circuit 110 buffer RAM 111 packing / buffer RAM control circuit 112 interface circuit (transfer means) 113 external device 114 timing signal generation circuit 115 CPU (detection means, control means) 115a ROM 115b RAM 116 crystal oscillator A home position B reading start position

Claims (13)

[Claims] 1. An image reading apparatus for conveying an image sensor in a sub-scanning direction and reading an image of a document line by line, comprising: detecting means for detecting a predetermined mark for image reading by the image sensor; Control means for determining a reference position of the image sensor based on the mark and starting reading of an image, wherein the detecting means includes a mark on the entire main scanning area before image reading by the image sensor at power-on. An image reading device for detecting a mark after detecting an image by the image sensor and selecting an arbitrary main scanning area after the image is read by the image sensor. 2. The image reading apparatus according to claim 1, wherein the mark is provided at or near a reading start position of the image sensor. 3. An image processing apparatus comprising: an A / D converter that converts an analog image signal read by the image sensor into a digital image signal; and a transfer unit that transfers the converted digital image signal to an external device. The image reading device according to claim 1 or 2, wherein 4. The image reading apparatus according to claim 1, wherein reading of an image is started from a predetermined position based on a reference position. 5. After determining the reference position of the image sensor and moving the image sensor to a predetermined position, the entire main scanning area is selected within a predetermined range in the sub-scanning direction, and the mark is detected again. 5. The image reading device according to claim 1, wherein the reference position is determined again according to the detected mark, and the image sensor is moved. 6. An image reading method for reading an image of a document line by line by transporting an image sensor in a sub-scanning direction, wherein a predetermined mark provided for image reading by the image sensor is detected. While determining the reference position of the image sensor based on the detected mark to start reading the image, the detection means,
Before the image reading by the image sensor at the time of power-on, the detection of the mark is performed for the entire main scanning area, and after the image reading by the image sensor, an arbitrary main scanning area is selected to detect the mark. An image reading method, comprising: 7. The image reading method according to claim 6, wherein the mark is provided at or near a reading start position of the image sensor. 8. The image reading method according to claim 6, wherein reading of an image is started from a predetermined position based on a reference position. 9. After determining the reference position of the image sensor and moving the image sensor to a predetermined position, the entire main scanning area is selected within a predetermined range in the sub-scanning direction, and the mark is detected again. 9. The image reading method according to claim 6, wherein the reference position is determined again according to the detected mark, and the image sensor is moved. 10. A storage medium storing a program for reading an image of a document line by line by conveying an image sensor in a sub-scanning direction, and detecting a predetermined mark for reading the image of the image sensor. Determine the reference position of the image sensor based on the detected mark and start reading the image, and before the image is read by the image sensor when power is turned on, detect the mark for the entire main scanning area, A storage medium storing a program for selecting an arbitrary main scanning area and detecting the mark after image reading by an image sensor. 11. A program for converting an analog image signal read by the image sensor into a digital image signal, and storing a program for transferring the converted digital image signal to an external device. Storage medium. 12. The storage medium according to claim 10, wherein a program for starting image reading from a predetermined position based on a reference position is stored. 13. After determining the reference position of the image sensor and moving the image sensor to a predetermined position, the entire area of the main scanning is selected within a predetermined range in the sub-scanning direction, and the mark is detected again. A program for determining a reference position again according to the detected mark and moving the image sensor is stored.
2. The storage medium according to any one of the above.