JP2004094735A - Optical character recognizing device and method for retaining image data of image buffer in same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical character recognizing device having a form transport-type scanner capable of constantly retaining the optimum form image even if the transport speed of the form is accelerated and the plurality of forms having different sizes and paper thicknesses are mixed and a method for retaining the image data of an image buffer in the same. <P>SOLUTION: A histogram creation section 23 creates a histogram in the transport direction of the slip P on the basis of the image data of white pixels when the image data (the white pixels) of the form is contained in the image data supplied to the image buffer 22. A form end detection section 24 detects the tip of the form P from the histogram. A buffer control section 25 instructs the ring type image buffer 22 to start writing upon receiving the detection signal of the form end from the slip end detection section 24 to write the image data of the form P to be read on the image buffer 22. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical character recognition device provided with a form transport type scanner, and a method for holding image data in an image buffer in the optical character recognition device.
[0002]
Further, the present invention relates to an optical character recognition device and an optical character recognition device which are suitably applied to realize a scanner mechanism for transporting and reading a plurality of types of forms having different sizes of paper at high speed. The present invention relates to a method for holding image data in an image buffer.
[0003]
[Prior art]
2. Description of the Related Art An optical character recognition device provided with a form transport type scanner for reading an image of a form to be read on a form transport path has an image buffer for storing image data of a form image read by the scanner. In this image buffer, a form transport control device for controlling the transport of the form controls a start address and an end address for storing image data.
[0004]
FIG. 3 is a block diagram showing a configuration of a conventional image data holding mechanism of a scanner unit in the optical character recognition device. In FIG. 3, an image sensor (CCD) 31 for reading an image of a form (P) conveyed on a conveyance path, and a leading end and a rear end of the form (P) in the conveying direction are detected by a form conveying mechanism of the scanner unit. A form detection sensor 32, a form transport motor 33 for transporting the form (P) on the transport path in a predetermined transport direction (the direction of the arrow in the drawing) at a predetermined transport speed, and the like are provided, and the form transport motor 33 is controlled to A form transport control device 34 for controlling the image sensor 31 and an image buffer described later based on the detection signal of the detection sensor 32 is provided.
[0005]
Further, the scanner unit includes an A / D conversion / image processing unit 35 that converts a signal (analog signal) of a form image read by the image sensor 31 into a digital image, and an A / D conversion / image processing unit 35. An image buffer 36 for holding image data of the processed form image is provided.
[0006]
Here, the form (P) sent out on the transport path of the form transport mechanism is transported in the direction of the arrow, and the leading end thereof is detected by the form detection sensor 32 before the image sensor 31. The form transport control unit 34 controls the writing of the image sensor 31 based on the detection signal. For example, a few mm before the form (P) arrives at the image sensor 31, the image buffer 36 is instructed to start writing image data. In accordance with this instruction, the image buffer 36 starts writing image data of the form image read by the image sensor 31.
[0007]
When the writing of the image data is completed, the form detection sensor 32 detects the trailing end of the form (P) or writes the form data from the form transport control device 34 to the image buffer 36 after a predetermined form length has elapsed. Termination is instructed. At this time, when the conveyance speed of the form (P) is constant, the distance between the detection position (P1) of the form detection sensor 32 and the reading position (P2) of the image sensor 31 is appropriately maintained, so that the image buffer 36 holds the entire form image (from the front end to the rear end).
[0008]
However, in the image data holding mechanism in the above-described conventional scanner unit, as the transport speed of the form (P) is increased, the size of the form and the thickness of the form are mixed. Depending on the form transport state, the form transport control device 34 may not be able to appropriately instruct the start or end of writing the image data to the image buffer 36.
[0009]
As a result, the image of the entire form is not correctly written on the image buffer 36, the position of the form image is not fixed, an image with a cut or missing upper or lower end is written, or in an extreme case, the entire image is written. It may not be written.
[0010]
For example, if the write start timing to the image buffer 36 is delayed, as shown in FIG. 4, the image buffer 36 holds the form image with the trailing end missing, and the entire form image cannot be correctly held. There is. In particular, in a system that allows a mixture of a plurality of types of forms having different sizes and paper thicknesses, the conveyance speed of the form (P) is accelerated before the image sensor 31 provided on the conveyance path of the form conveyance mechanism to increase the speed. When the document is transported and the form image is read, the above-described problem becomes conspicuous.
[0011]
[Problems to be solved by the invention]
As described above, in the related art, in the image data holding mechanism in the scanner unit, when increasing the transport speed of a form, and when allowing the mixture of the form size and the form paper thickness, the form The transfer control device cannot appropriately instruct the start or end of writing the image data to the image buffer, and thus the image position of the form image held in the image buffer is not constant, or the top or bottom of the form image is not There has been a problem that defects such as dropout and not writing of the entire form image occur.
[0012]
The present invention has been made in view of the above circumstances, and always maintains an optimal form image even when a form is transported at a high speed and a plurality of forms having different sizes and paper thicknesses are mixed. It is an object of the present invention to provide an optical character recognizing device provided with a form-conveying type scanner and a method for holding image data in an image buffer in the optical character recognizing device.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, an optical character recognition device according to the present invention includes a form reading unit that reads a form to be read on a form transport path, and an image to start capturing from the first image data read by the form reading unit. The image processing apparatus further includes a tip detection unit that detects a tip of data, and a ring-type image buffer that stores the image data based on a detection signal of the tip detection unit.
[0014]
Further, the optical character recognition device of the present invention is a form reading unit that reads a form to be read on a form transport path, a ring-type image buffer that stores image data read by the form reading unit, and a form reading unit. Histogram generating means for generating a histogram in the transport direction from the read image of the leading image data; andcontrol means for instructing a start of writing the image data to the image buffer based on the histogram generated by the histogram generating means. It is characterized by having.
[0015]
As described above, according to the present invention, the image buffer is formed into a ring buffer format, and the leading end of the image data to be taken into the image buffer is detected from the leading image data supplied to the image buffer. With this configuration, the input form image can be held and output in an appropriate state within a limited image buffer capacity regardless of the form transport state.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a block diagram illustrating a configuration of an image data holding mechanism of a scanner unit of an optical character recognition device according to an embodiment of the present invention.
[0018]
In FIG. 1, a form transport mechanism of a scanner unit includes an image sensor (CCD) 11 for reading an image of a form (P) to be read conveyed on a transport path, and a predetermined form on the form (P) to be read on the transport path. A form transport motor 12 and the like for transporting the document at a predetermined transport speed in the transport direction (the direction of the arrow shown in the figure) are provided, and a form for controlling each mechanism such as the image sensor 11 and the form transport motor 12 provided in the form transport mechanism. A transfer control device 13 is provided.
[0019]
Further, the scanner unit includes an A / D conversion / image processing unit 21, a ring-type image buffer 22, a histogram creation unit 23, a form edge detection unit 24, a buffer control unit 25 including a read address conversion mechanism 25a, and the like. Can be
[0020]
The A / D conversion / image processing unit 21 converts the signal (analog signal) of the form image read by the image sensor 11 into a digital image, and outputs image data of the form to be read. The ring type image buffer 22 stores the image data of the form processed by the A / D conversion / image processing unit 21.
[0021]
The histogram creating unit 23 creates a histogram of the image data of the form to be read (P) in the transport direction from the image data supplied to the image buffer 22. The form edge detection unit 24 detects the leading edge and the trailing edge of the image data of the form to be read (P) to be loaded into the image buffer 22 based on the histogram created by the histogram creating unit 23.
[0022]
The buffer control unit 25 controls writing / reading of the ring type image buffer 22 based on the detection signal of the form edge detection unit 24. When reading out the image data held in the ring type image buffer 22, the read address conversion mechanism 25 a provided in the buffer control unit 25 reads the physical address of the leading end of the form of the image data held in the image buffer 22, Alternatively, the physical address (for example, address A0000 in the example shown in FIG. 2) a predetermined amount before the form leading end (for example, 10 mm before the form leading end) is converted to an address 0 for starting reading.
[0023]
FIG. 2 is an operation explanatory diagram of the image data holding mechanism according to the embodiment.
[0024]
2A is a diagram showing a relationship between image data of a form to be read (P) stored in the ring-type image buffer 22 and a physical address of the image buffer 22. FIG. Here, the image buffer 22 is configured in a 1-Mbyte ring buffer format having a 20-digit address range (0000 to FFFFF), and stores (circulates) image data continuously starting from an arbitrary address. It has a configuration that can be used.
[0025]
FIG. 2B is a diagram showing a histogram in the transport direction of the image data of the form to be read (P) created by the histogram creating unit 23 based on the image data written into the image buffer 22 in the ring format. FIG. 2C is a diagram illustrating a leading edge detection signal in the transport direction of the image data detected by the form edge detecting unit 24 based on the histogram created by the histogram creating unit 23.
[0026]
FIG. 2D shows a read address conversion mechanism for reading the image data held in the ring type image buffer 22 based on the detection signal of the leading end in the transport direction of the image data detected by the form edge detection unit 24. It is a figure which shows the example of address conversion of 25a. Here, in consideration of the skew amount of the form, the physical address (address A0000) on the memory (image buffer 22) a predetermined amount (for example, 10 mm before the form front) from the top of the form detected by the form end detection unit 24. Is converted to a read start address (address 0).
[0027]
Here, the operation in the embodiment of the present invention will be described with reference to FIGS.
[0028]
The form to be read (P) sent out on the conveyance path of the form conveyance mechanism is conveyed to the reading position of the image sensor (CCD) 11 by the conveyance path, and the form image of the form to be read (P) is read. The form image (analog signal) of the form to be read (P) read by the image sensor (CCD) 11 is digitized by the A / D conversion / image processing unit 21 to obtain an image of the form to be read (P). The data is supplied to the ring-type image buffer 22 as data.
[0029]
If the top image data supplied to the image buffer 22 includes the image data of the form (white pixels obtained from the top margin of the form), the histogram creating unit 23 uses the image data of the white pixels as a basis. Then, a histogram in the transport direction is created and sent to the form edge detection unit 24. The form edge detection unit 24 detects the leading end of the image data of the read form (P) to be taken into the image buffer 22 from the histogram created by the histogram creating unit 23, and sends a detection signal of the leading end of the form to the buffer control unit 25. Send out.
[0030]
When receiving the detection signal of the leading end of the form from the form end detecting section 24, the buffer control section 25 instructs the ring-type image buffer 22 to start writing and outputs the image buffer 22 from the A / D conversion / image processing section 21. The image data of the read form (P) to be read is written. FIG. 2A shows an example of the state of writing image data to the image buffer 22 at this time. Here, the image data of the form to be read (P) is written between the physical addresses A0000 to 30000 (A0000 to FFFFF, 0000 to 30000) of the ring-type image buffer 22. Similarly, when the form detection unit 24 detects the trailing end of the image data of the form to be read (P), the buffer control unit 25 instructs the end of writing to the ring-type image buffer 22 and completes the storage of the image data. I do.
[0031]
At this time, since the image buffer 22 has a ring format, when the write address of the image data reaches the physical address FFFFF, the subsequent image data is written from the physical address 00000. As a result, the image data of the form to be read (P) is stored in the limited memory capacity (1 Mbytes in this example) without any loss.
[0032]
On the other hand, when reading the image data of the form to be read (P) stored in the ring-type image buffer 22, the read address conversion mechanism 25 a provided in the buffer control unit 25 uses the form detected by the form end detection unit 24. The physical address (address A0000) on the image buffer 22 that is a predetermined amount before the leading edge (for example, 10 mm before the leading edge of the form) is converted into a read start address (address 0). Thus, when the buffer control unit 25 receives an instruction to read the image buffer 22 from the recognition processing unit, the buffer control unit 25 starts reading image data with the physical address A0000 as the starting point of the read address. FIG. 2D shows an example of address conversion at this time. Therefore, when the recognition processing unit reads the image data of the form to be read (P) from the image buffer 22, if the recognition processing unit always reads the form image from the address 0, the recognition processing unit does not have a missing part several mm before the leading end of the form. Image data can be obtained.
[0033]
【The invention's effect】
As described above in detail, according to the present invention, in an optical character recognition device equipped with a form transport type scanner, a form transport speed is increased, and a plurality of types of forms having different sizes and thicknesses are used. It is possible to always keep the optimal form image even for the mixture or the like.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image data holding mechanism of a scanner unit of an optical character recognition device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of an operation of the image data holding mechanism according to the embodiment.
FIG. 3 is a block diagram showing a configuration of a conventional image data holding mechanism of a scanner unit in the optical character recognition device.
FIG. 4 is a diagram showing an example of missing image data by a conventional image data holding mechanism.
[Explanation of symbols]
11 ... Image sensor (CCD)
Reference numeral 12: a form transport motor 13 ... a form transport control device 21 ... an A / D conversion / image processing unit 22 ... a ring-type image buffer 23 ... a histogram creation unit 24 ... a form end detection unit 25 ... a buffer control unit 25a ... a read address conversion mechanism P ... read form

Claims (7)

A form reading unit that reads a form to be read on a form transport path;
From the leading image data read by the form reading unit, a leading edge detecting means for detecting a leading edge of image data to start capturing,
An optical character recognition device, comprising: a ring-type image buffer that stores the image data based on a detection signal of the tip detection unit. A form reading unit that reads a form to be read on a form transport path;
A ring-type image buffer for storing the image data read by the form reading unit,
Histogram generation means for generating a histogram in the transport direction from the image of the leading image data read by the form reading unit,
An optical character recognition device, comprising: control means for instructing the start of writing of the image data into the image buffer based on the histogram generated by the histogram generation means. The control means includes:
Tip detection means for detecting the tip of the image data based on the histogram generated by the histogram generation means,
3. The optical character recognition device according to claim 2, further comprising: a buffer control unit that controls writing and reading of the image buffer based on a detection signal of the tip detection unit. 2. The image processing apparatus according to claim 1, wherein the buffer control unit includes a read address conversion mechanism that performs a relative address conversion between a write start address and a read start address of the image buffer during read control of the image buffer. 3. The optical character recognition device according to 3. In a method of holding image data in an image buffer in an optical character recognition device,
The image buffer is constituted by a ring buffer,
From the top image data read by the form reading unit, the leading end of the image data to start loading is detected,
And storing the image data in the ring buffer based on the detection of the leading edge. In a method of holding image data in an image buffer in an optical character recognition device,
The image buffer is constituted by a ring buffer,
Generate a histogram in the transport direction from the image of the first image data read by the form reading unit,
Detecting the tip of the image data based on the generated histogram,
A method for holding image data in an image buffer in an optical character recognition device, wherein the timing of writing the image data to the ring buffer is controlled based on the detection of the leading end. 7. The image forming apparatus according to claim 6, wherein when reading the image data stored in the ring buffer, reading is started from a storage position that is a predetermined amount before a leading end position of the image data stored in the ring buffer. A method for holding image data in an image buffer in an optical character recognition device.

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