JP2009230287A - Reading apparatus, written information processing system, controller for reading apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the degradation of reading precision in a code image associated with a posture change of a reading apparatus with respect to a medium. <P>SOLUTION: A digital pen includes the first infrared LED 63a and the second infrared LED 63b for irradiating a printed document formed with the code image, with a light, a light emission control part 612 for selecting the LED lighting on when performing a writing operation onto the printed document by a user, an infrared CMOS 64 for receiving a reflected light from the printed document irradiated with the light from the selected LED, and an image processing part 614 for image-processing photoreception results by the infrared CMOS 64, to obtain the code image, for decoding the obtained code image, to find identification information and positional information, for detecting a generation state of void in the photoreception results, and for determining the propriety of switching the lighting-on infrared LED 64, based on detection results. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reading device, a writing information processing system, a control device for the reading device, and a program.

  2. Description of the Related Art In recent years, for example, a pen-type input device used by a user in hand has attracted attention as an input device for a computer device. This type of pen-type input device includes a reading device that reads an image formed on a medium in addition to a recording device as a so-called pen that writes on a medium. Such a reading apparatus is realized by including a light source that irradiates light to a medium and a light receiving unit that receives reflected light from the medium (see, for example, Patent Document 1).

Special table 2004-527853 gazette

  By the way, in the pen-type input device, depending on the orientation of the reading device with respect to the medium, specularly reflected light that is irradiated from the light source and reflected by the medium enters the light receiving unit, and as a result, the reading accuracy of the code image is lowered. There was a thing.

  An object of the present invention is to suppress a decrease in reading accuracy of a code image accompanying a change in posture of a reading device with respect to a medium.

According to the first aspect of the present invention, when a plurality of irradiation means for irradiating light to the medium on which the code image is formed and any one of the plurality of irradiation means is turned on, the irradiation is performed. A light receiving means for receiving reflected light from the medium irradiated with light, an acquisition means for acquiring the code image from a light reception result of the reflected light by the light receiving means, and a reflection light of the reflected light by the light receiving means. The reading apparatus includes a switching unit that switches an irradiation unit to be turned on from among the plurality of irradiation units according to a whiteout occurrence state in a light reception result.
According to a second aspect of the present invention, the plurality of irradiation units include a first irradiation unit and a second irradiation unit that irradiate light toward a reading position of the medium by the light receiving unit, and the first irradiation unit. When the specularly reflected light that is irradiated by the irradiating means and reflected by the medium is incident on the reading means, the specularly reflected light that is irradiated by the second irradiating means and reflected by the medium is incident on the reading means. 2. The reading apparatus according to claim 1, wherein an irradiation direction of light of each of the first irradiation unit and the second irradiation unit is set so that the first irradiation unit and the second irradiation unit are not.
According to a third aspect of the present invention, the plurality of irradiation units include a first irradiation unit and a second irradiation unit that irradiate light toward a reading position of the medium by the light receiving unit, and the first irradiation unit. A first optical axis from the irradiation unit to the reading position and a second optical axis from the second irradiation unit to the reading position are the third light beams from the reading position to the light receiving unit. 3. The reading apparatus according to claim 1, wherein the reading apparatus has a symmetric positional relationship with respect to an axis.
According to a fourth aspect of the present invention, the switching unit detects the occurrence of the whiteout caused by an excessive amount of reflected light incident on the light receiving unit from the irradiation unit via the medium. A reading device according to any one of claims 1 to 3.
The invention according to claim 5 is characterized in that the switching means detects the occurrence of whiteout due to specularly reflected light entering the light receiving means from the irradiation means via the medium. The reading device according to claim 1.
According to a sixth aspect of the present invention, the light receiving means is configured by arranging a plurality of light receiving elements at a periphery of a first imaging area configured by arranging a plurality of light receiving elements and the first imaging area. A two-dimensional sensor having a second imaging region, wherein the acquisition unit acquires the code image from a light reception result received in the first imaging region of the two-dimensional sensor, and the switching unit includes the switching unit 6. The reading device according to claim 1, wherein the whiteout occurrence state is detected from a light reception result received in the second imaging region of a two-dimensional sensor.
According to a seventh aspect of the present invention, the switching means includes a whiteout occurrence state caused by reflected light from a drawing material constituting the code image on the medium or a whiteout caused by reflected light from the medium. The reading apparatus according to any one of claims 1 to 6, wherein at least one of the occurrence states is detected.
The invention according to claim 8 is the reading device according to any one of claims 1 to 7, further comprising writing means for writing on the medium.

The invention according to claim 9 is read by the medium on which the code image is formed, the electronic writing tool for reading the code image from the medium, and the electronic writing tool in accordance with a writing operation on the medium by a user. An information processing device that acquires information related to the code image and stores the writing content on the medium in association with the medium or an electronic document printed on the medium based on the acquired information; The writing instrument is a writing means for writing on the medium, a plurality of irradiation means for irradiating the medium with light, and when any of the irradiation means is turned on, A light receiving means for receiving reflected light from the medium irradiated with light by the irradiating means; an acquisition means for acquiring the code image from a light reception result of the reflected light by the light receiving means; and Transmission means for transmitting the information related to the acquired code image to the information processing apparatus, and the plurality of irradiation means according to the occurrence of whiteout in the light reception result of the reflected light by the light receiving means. A writing information processing system comprising switching means for switching irradiation means to be lit from inside.
According to a tenth aspect of the present invention, in the electronic writing instrument, the switching unit includes the white light caused by an excessive amount of reflected light incident on the light receiving unit from any one of the irradiation units via the medium. The handwritten information processing system according to claim 9, wherein a jump occurrence state is detected.
According to an eleventh aspect of the present invention, in the electronic writing instrument, the switching unit includes the occurrence of the whiteout caused by specularly reflected light entering the light receiving unit from any one of the irradiation units through the medium. The writing information processing system according to claim 9, wherein the writing information processing system is detected.
According to a twelfth aspect of the present invention, in the electronic writing instrument, the light receiving unit includes a first area configured by arranging a plurality of light receiving elements, and a plurality of light receiving elements arranged at a periphery of the first area. A two-dimensional sensor having a configured second region, wherein the acquisition unit acquires the code image from a light reception result received in the first region of the two-dimensional sensor, and the switching unit includes: 12. The writing information processing system according to claim 9, wherein the whiteout occurrence state is detected from a light reception result received in the second region of the two-dimensional sensor.
According to a thirteenth aspect of the present invention, the electronic writing instrument acquires the identification information of the medium or the position information in the medium as the information related to the code image from the code image acquired by the acquisition unit and transmits the information. The information processing apparatus reads out an electronic document associated with the identification information and superimposes a writing locus corresponding to the position information on the electronic document. The handwritten information processing system according to any one of claims 9 to 12.

  In the invention according to claim 14, light is emitted from the lighting instruction means for turning on any one of the plurality of light sources that emit light to the medium on which the code image is formed, and the light source that is turned on. A plurality of light receiving instructions for receiving reflected light from the medium; obtaining means for acquiring the code image from the light receiving result of the reflected light; and And a switching instructing unit that outputs an instruction to switch the light source to be lit to the lighting instructing unit.

According to the fifteenth aspect of the present invention, there is provided a function of causing a computer to turn on any one of a plurality of light sources that irradiates light onto a medium on which a code image is formed. A function of acquiring the code image from a light reception result of reflected light from the irradiated medium, and a function of switching a light source to be turned on from the plurality of light sources according to a whiteout occurrence state in the light reception result. This is a program to be realized.
The invention described in claim 16 is the program according to claim 15, further causing the computer to realize a function of acquiring predetermined information embedded in the code image from the acquired code image. .

According to the first aspect of the present invention, it is possible to suppress a decrease in the reading accuracy of the code image due to a change in the posture of the reading device with respect to the medium.
According to the invention described in claim 2, when switching from the first irradiation means to the second irradiation means and when switching from the second irradiation means to the first irradiation means, the medium The direction of the regular reflection light from the light receiving means can be shifted from the light receiving means.
According to the third aspect of the present invention, when switching from the first irradiation means to the second irradiation means and when switching from the second irradiation means to the first irradiation means, the medium The direction of the regular reflection light from the light receiving means can be shifted from the light receiving means.
According to the fourth aspect of the present invention, it is possible to detect whiteout caused by an excessive amount of reflected light incident on the light receiving means.
According to the fifth aspect of the present invention, it is possible to detect whiteout caused by specular reflection light from the medium entering the light receiving means.
According to the sixth aspect of the present invention, the irradiation means can be switched before the light receiving result of the first imaging region is affected by the whiteout.
According to the seventh aspect of the present invention, it is possible to detect whiteout caused by the code image formed on the medium or whiteout caused by the medium itself.
According to the eighth aspect of the present invention, it is possible to acquire a writing trajectory with respect to a medium using a code image acquisition result.
According to invention of Claim 9, the fall of the reading accuracy of the code | symbol image accompanying the change of the attitude | position of the electronic writing instrument with respect to a medium can be suppressed.
According to the tenth aspect of the present invention, it is possible to detect whiteout caused by an excessive amount of reflected light incident on the light receiving means.
According to the eleventh aspect of the present invention, it is possible to detect whiteout caused by specularly reflected light from the medium entering the light receiving means.
According to the twelfth aspect of the present invention, it is possible to switch the irradiating means before the influence of whiteout appears on the light reception result of the first imaging region.
According to the thirteenth aspect of the invention, it is possible to improve the accuracy of the writing locus when the writing locus is added to the electronic document.
According to the fourteenth aspect of the present invention, it is possible to suppress a decrease in the reading accuracy of the code image due to a change in the posture of the reading device with respect to the medium.
According to the fifteenth aspect of the present invention, it is possible to suppress a decrease in the reading accuracy of the code image accompanying a change in the posture of the reading device with respect to the medium.
According to the sixteenth aspect of the present invention, information can be acquired from the code image.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
First, the overall configuration of the handwriting information management system in the present embodiment will be described.
FIG. 1 is a diagram showing an example of the configuration of the handwriting information management system of the present embodiment. This handwriting information management system is configured by connecting a terminal device 10, a document server 20, an identification information server 30, an image forming device 40, and a terminal device 50 to a network 80. A digital pen 60 is connected to the terminal device 50 via a communication device 70.

The terminal device 10 is used to output an electronic document print request. As such a terminal device 10, for example, a personal computer (PC) is used.
The document server 20 stores an electronic document. When there is a print request for the electronic document, the document server 20 instructs the formation of a superimposed image in which an image of the electronic document, that is, a document image and a code pattern image described later are superimposed. As such a document server 20, for example, a general-purpose server computer is used.
The identification information server 30 as an example of the information processing apparatus issues identification information to be given to the medium. Then, the identification information server 30 manages the issued identification information in association with the electronic document printed on the medium. In the present embodiment, the identification information server 30 also has a function of specifying an electronic document that associates the pull information. As such an identification information server 30, for example, a general-purpose server computer is used.

The image forming apparatus 40 forms a superimposed image including a document image and a code pattern image on a medium and outputs it as a printed document 90. Here, an electrophotographic system is used as an image forming system in the image forming apparatus 40, but any other system such as an ink jet system may be employed. In this embodiment, the document image is formed using cyan, magenta, and yellow toners, and the code pattern image is formed using black toner. This is because the black toner has more infrared light absorption than the cyan, magenta, and yellow toners, and the digital pen 60 can read the code pattern image. However, the present invention is not limited to this, and the document image may be formed using cyan, magenta, and yellow toners, and the code pattern image may be formed using special toner. Here, examples of the special toner include invisible toner having a maximum absorption rate of 7% or less in the visible light region (400 to 700 nm) and an absorption rate of 3% or more in the near infrared region (800 to 1000 nm). . Here, “visible” and “invisible” are not related to whether or not they can be recognized visually. Specifically, “visible” and “invisible” are distinguished based on whether or not an image formed on a printed medium can be recognized by the presence or absence of color development due to absorption of a specific wavelength in the visible light region. . Also, “invisible” includes those that have some color developability due to absorption of a specific wavelength in the visible light region but are difficult to recognize with human eyes.
A digital pen 60 as an example of a reading device or an electronic writing instrument is a reading device having a function of recording (writing) characters and figures on a printed document 90. In the present embodiment, the digital pen 60 also has a function of transmitting information acquired from the code pattern image formed on the print document 90 to the terminal device 50. For example, a personal computer is used as the terminal device 50.

Next, the operation in this handwriting information management system will be described.
First, an operation when outputting the print document 90 in the handwriting information management system will be described.
When a print request for an electronic document is made from the terminal device 10, the document server 20 receives the print request from the terminal device 10 and instructs the image forming apparatus 40 to print the electronic document that is the target of the print request. As a result, the image forming apparatus 40 prints the document image of the electronic document on a medium such as paper. At this time, the image forming apparatus 40 prints a code pattern image on the medium in addition to the document image. Document 90 is output.
Here, the code pattern image is an image of the identification code and position code obtained by encoding the identification information and position information. The identification information is information for uniquely identifying a medium, and is issued by the identification information server 30 in the present embodiment. The position information is information for specifying the coordinate position on the medium, and is generated by the document server 20 in the present embodiment. Note that the identification information may uniquely identify a document image printed on a recording medium, for example, in addition to uniquely identifying a medium.

Next, an operation when writing is performed on the print document 90 using the digital pen 60 will be described.
When the user writes with the digital pen 60 on the printed document 90 on which the document image and the code pattern image are printed, the digital pen 60 writes handwritten information (handwriting information) based on the position information included in the code pattern image. Generate. At the same time, the digital pen 60 recognizes the identification information included in the code pattern image. The recognized identification information and the generated handwriting information are sent to the document server 20 via the terminal device 50. The document server 20 that has received the identification information and the handwriting information specifies the electronic document corresponding to the print document 90 based on the identification information, and stores the specified electronic document and the handwriting information in association with each other.

In this specification, electronic data that is the basis of an image recorded on a medium is expressed as “electronic document”. However, this does not mean only data obtained by digitizing a “document” including text. For example, "electronic document" including image data such as pictures, photos, figures (regardless of raster data or vector data), data recorded by database management software or spreadsheet software, and other printable electronic data It is said.
In the present specification, the “medium” may be any material as long as it can print an image. A typical example is paper, but it may be a plastic sheet such as an OHP sheet or a metal plate.

Next, a code pattern image as an example of a code image used in the present embodiment will be described in detail.
The code pattern image is an image of a code obtained by encoding predetermined information. In this example, both the identification information and the position information are included, but only one of the information is included. For example, it may include other information such as a synchronization code described later. In the present embodiment, a code block that is a constituent unit of information included in a code pattern image is configured by a plurality of unit code patterns. The unit code pattern is the minimum unit of information embedding, and is represented by forming a unit image at a predetermined position. Here, a unit image having any shape may be used. In the present embodiment, a dot image (hereinafter simply referred to as “dot”) is used as an example of a unit image, but an image having another shape such as a hatched pattern may be used.

(Unit code pattern)
FIG. 2 is an explanatory diagram showing an example of a unit code pattern constituting a code pattern image. In this example, as an example of a predetermined section, two places are selected from the places where a total of nine dots in three places in the vertical direction (hereinafter referred to as 3 × 3 places) can be arranged, and the dots are arranged. To do. In this case, there are 36 dot arrangement combinations of unit code patterns (36 = ₉ C ₂ ) (where _m C _n = m! / {(Mn)! × n!}). When recording at a resolution of 600 dpi, one dot size (square size) in FIG. 2 is 2 pixels in the vertical direction and 2 pixels in the horizontal direction (hereinafter referred to as 2 × 2 pixels). Note that 2 × 2 pixels are rectangular with a side length of 84.6 μm in the calculation, but the recorded toner image has a circular shape of about φ100 μm. Accordingly, the unit code pattern is a rectangle (0.5076 × 0.5076 mm) having a side length of 0.5076 mm.

Of the 36 combinations, 4 (4 = 2 ² ) are used as synchronization codes for detecting a code block (described later) and detecting a rotation angle. At this time, in order to detect the rotation angle of the code block in units of 90 degrees, the four patterns are selected to be 90-degree rotationally symmetrical patterns. That is, if any one of the four patterns is embedded as a synchronization code at the time of image generation, the rotation angle of the code block (the code synchronized on the two-dimensional array) depends on the angle at which the synchronization code is detected at the time of decoding. Which direction of 0/90/180/270 degrees of the block is facing) can be determined and corrected.

The remaining 32 combinations (32 = 2 ⁵ ) of the 36 combinations are used for embedding information of 5 bits per unit code pattern. Here, FIG. 3 shows 36 dot arrangements that can be taken by the unit code pattern of FIG. 2 described above. In FIG. 3, a space between dots is omitted for simplification of display.
Note that the unit code pattern is not limited to the method of arranging dots in two of the nine locations as shown in the figure, and may be three or four. That is, it should be smaller than nine. For example, the combination of dot arrangement with the configuration of placing dots in positions 3 of 9 points becomes 84 kinds (84 = 9 _{C 3).} Further, the number of places where dots can be arranged is not limited to nine (3 × 3), but may be other numbers, for example, four (2 × 2) or 16 (4 × 4).

(Synchronous code combination)
FIG. 4 shows combinations of synchronization codes that can be selected from 36 dot arrangements that the unit code pattern of FIG. 2 can take. All the combinations shown in FIG. 4 are 90-degree rotationally symmetric. Any combination is used as four code patterns used for the synchronization code.

(Code block)
FIG. 5 shows an example of a code block for embedding a synchronization code, a position code, and an identification code. In this example, 5 × 5 unit code patterns shown in FIG. 2 are arranged to form a code block.

(Synchronous code)
The synchronization code shown in FIG. 4 is arranged at the upper left position of the code block shown in FIG. That is, one of the synchronization codes shown in FIGS. 4A to 4H is selected, and one selected from the four unit code patterns included in the selected synchronization code is arranged at the upper left of the code block. To do.

(Position code)
In the code block shown in FIG. 5, an X position code obtained by encoding information unique to the position in the X direction is arranged using four unit code patterns adjacent to the right side of the synchronization code. In the code block shown in FIG. 5, a Y position code obtained by encoding information unique to a position in the Y direction is arranged using four unit code patterns adjacent to the lower side of the synchronization code. Since each of the X position code and the Y position code uses four unit code patterns, each can store information of 20 bits (5 bits / unit code pattern × 4 pieces).
It should be noted that instead of using 32 types of information embedding patterns (32 = 2 ⁵ ) as position codes, only 16 types of patterns may be used. In this case, since the amount of information per unit code pattern is 4 bits (16 = 2 ⁴ ), the position code is 16 bits (4 bits / unit code pattern × 4 pieces) of information.

In this embodiment, M sequences are used as such position codes. For example, if a 12th-order M sequence is used, the sequence length of the M sequence is 4095 (= 2 ¹² −1). When 16 types of patterns are selected as the unit code pattern of the position code, information of 4 bits is stored in each unit code pattern, so that information of 16 bits (4 bits × 4 pieces) is stored in one code block. Accordingly, the M sequence having a sequence length of 4095 is divided and stored in 255 (= 4095 ÷ 16) code blocks. Since the width of one code block is 2.538 mm (= 0.5076 mm / unit code pattern width × 5), the length of 255 consecutive code blocks is 647.19 mm, and the length of 647.19 mm is the code. It becomes. That is, even A2 size (420 × 594 mm) paper is encoded.

  In addition, although the example which encoded the position with one M series was shown here, you may further increase the position encoded by concatenating several M series. For example, even when an 11th-order M series is used, A4 size paper is encoded by connecting four of them.

(Identification code)
In the code block shown in FIG. 5, identification codes are arranged in the remaining areas, that is, positions where no synchronization code or position code exists. Since 16 unit code patterns (4 × 4) are arranged in this area, 80 bits (5 bits / unit code pattern × 16) of information can be stored. Since the unit code pattern of the present embodiment is a multi-level code, errors that occur during reading and the like also occur in units of the unit code pattern. Accordingly, it is desirable that the error correction code be a system that can perform error correction in units of blocks. If an RS code, which is a known block error correction code system, is used for the identification code, the block length of the RS code becomes 5 bits, which is the information amount of the unit code pattern. In this case, the code length of the RS code is 16 blocks (= 80 bits / 5 bits / block). For example, if the correction capability of 3 blocks is provided, the information code length is 10 blocks (= 16 blocks−3 blocks × 2). It becomes. In this case, information of 50 bits (= 5 bits / block × 10 blocks) is embedded in the identification code area.

(Position code arrangement)
FIG. 6 shows an example in which position codes are arranged in a code pattern image. As described above, the M-sequence is divided into blocks each having 4 bits, which is the number of unit code pattern bits of the position code, and the divided blocks are sequentially arranged in a region sandwiched between synchronization codes. Although only the X position code is shown in FIG. 6, the same applies to the Y position code.
Since each code block has a synchronization code, the X position code and the Y position code are not arranged consecutively, and a synchronization code is arranged every four unit code patterns of the X position code and the Y position code. Will be.

(Distribution of identification codes)
FIG. 7 shows an example in which identification codes are arranged in a code pattern image. The identification code is arranged, for example, in the lower right quadrant of the synchronization code. Further, unlike the position code, the same information is always embedded in the identification code regardless of the image position.

Next, the digital pen 60 used for writing on the print document 90 and reading the writing locus will be described.
FIG. 8 is a diagram illustrating an outline of the configuration of the digital pen 60. The digital pen 60 detects the writing operation by the control unit 61 that controls the operation of the entire pen and the digital pen 60 by the pressure (writing pressure) applied to the pen tip 69 as an example of writing means, and puts the digital pen 60 into an operating state. The pen pressure detection switch 62 to be set, the first infrared LED (Light Emitting Diode) 63a that irradiates the medium with infrared light, and the second infrared LED 63b (in the following description, these are collectively referred to simply as the infrared LED 63). An infrared CMOS (Complementary Metal Oxide Semiconductor) 64 that captures an image is provided. Here, the first infrared LED 63a and the second infrared LED 63b are arranged so that their optical axes intersect with the print document 90 at different angles, details of which will be described later. The digital pen 60 includes an information memory 65 for storing identification information and position information, a communication circuit 66 as an example of a transmission unit for communicating with an external device (terminal device 50), and a battery for driving the digital pen 60. 67, a pen ID memory 68 for storing identification information (pen ID) of the digital pen 60 is further provided. These units are connected to the control unit 61.
In the digital pen 60 shown in FIG. 8, the direction from the near side to the far side in the figure is defined as the U direction. A direction from the right side to the left side in the figure is defined as a V direction. Furthermore, the direction from the lower side to the upper side in the figure is defined as the W direction. Here, the U direction, the V direction, and the W direction are orthogonal to each other. The U direction and the V direction correspond to the paper surface of the print document 90.

Next, the arrangement of the first infrared LED 63a and the second infrared LED 63b in the digital pen 60 will be described. Here, in the present embodiment, the first infrared LED 63a and the second infrared LED 63b function as a plurality of irradiation means, and the first infrared LED 63a serves as the first irradiation means. Each of the two infrared LEDs 63b functions as a second irradiation unit.
FIG. 9 is a view of the first infrared LED 63a, the second infrared LED 63b, and the infrared CMOS 64 constituting the digital pen 60 as seen from the IX direction shown in FIG. Therefore, in FIG. 9, the direction from the right side to the left side in the drawing is the U direction, and the direction from the back side to the near side in the drawing is the V direction.
In the present embodiment, the first infrared LED 63a and the second infrared LED 63b are respectively arranged so as to irradiate infrared light to the reading position R set in the vicinity of the writing position on the print document 90 by the pen tip 69. Is done. Further, the first infrared LED 63a and the second infrared LED 63b are symmetrical with respect to the light receiving axis (third optical axis) from the reading position R toward the infrared CMOS 64 when viewed from the IX direction shown in FIG. Be placed. Therefore, the first angle θ1 formed by the first illumination optical axis (first optical axis) from the first infrared LED 63a toward the reading position R and the light receiving axis and the second angle from the second infrared LED 63b toward the reading position R. The second angle θ2 formed by the second illumination optical axis (second optical axis) and the light receiving axis is equal. In the present embodiment, the sum of the first angle θ1 and the second angle θ2 is set to be 10 degrees or more. However, from the viewpoint of reducing the size of the digital pen 60, it is preferable that the sum of the first angle θ1 and the second angle θ2 is not large, for example, 30 degrees or less.
In the infrared CMOS 64, an infrared CMOS chip 641 (see FIG. 10 described later) is disposed so as to face the reading position R. In the digital pen 60, an optical system (not shown) such as a lens is provided between the reading position R and the infrared CMOS 64.

FIG. 10A is a diagram illustrating an example of the configuration of the infrared CMOS 64 provided in the digital pen 60.
An infrared CMOS 64 as an example of a light receiving means includes an infrared CMOS chip 641, a lead frame 642 electrically connected to the infrared CMOS chip 641, and the infrared CMOS chip 641 and the lead frame 642 in a resin mold. Package portion 643 integrated.

FIG. 10B is a diagram illustrating an example of a configuration of a light receiving surface in an infrared CMOS chip 641 as an example of a two-dimensional sensor.
In the infrared CMOS chip 641, a large number of phototransistors as light receiving elements are arranged in a matrix in the horizontal direction (referred to as the reference axis X direction) and the vertical direction (referred to as the reference axis Y direction). 8 and 9, in the state where the digital pen 60 is set upright in the W direction with respect to the print document 90, the X direction coincides with the U direction and the Y direction coincides with the V direction. ing. The infrared CMOS chip 641 outputs the received light data by a so-called XY address method that selects the output of the received light data for each cell. Further, since the infrared CMOS chip 641 adopts the XY address system, the light reception data of all the lines constituted by the cells, or the light reception data of half the lines thinned out every other line, for example, can be arbitrarily selected. Selected and output. In this case, if the output resolution of the former is 600 dpi, for example, the output resolution of the latter light reception data is half of the output resolution of the former, that is, 300 dpi. In this embodiment, the infrared CMOS chip 641 operates in a so-called global shutter system in which all cells are exposed at the same timing.

  In the present embodiment, on the light receiving surface of the infrared CMOS chip 641, 150 photocells in the X direction and 150 cells in the Y direction are arranged in a total of 22500 cells. As a result, in the entire imaging region S of the infrared CMOS chip 641, code image data having the number of pixels of 150 pixels × 150 pixels = 22500 pixels is acquired. However, as will be described later, in the detection of identification information and position information, code image data having the number of pixels of 100 cells × 100 cells = 10000 cells, that is, 10000 pixels, present in the center of the imaging region S is used. In the following description, an area of 100 cells × 100 cells existing in the center of the imaging area S is referred to as a first imaging area S1, and another area existing in the periphery thereof is referred to as a second imaging area S2. I will call it. Each cell constituting the infrared CMOS chip 641 outputs 8-bit data (256 levels from 0 to 255). This data approaches 0 as the amount of received light decreases (darker). The larger the amount (the brighter it is), the closer to 255.

  The imaging area S of the infrared CMOS chip 641 is configured to read an image of an area of about 4 mm × about 4 mm at the reading position R (see FIG. 9). For this reason, in the first imaging region S1, an image of an area of about 2.6 mm × about 2.6 mm is read. One cell constituting the infrared CMOS chip 641 reads an area of about 26 μm × about 26 μm. In addition, in the entire imaging region S of the infrared CMOS 641, about 64 unit code patterns (0.5076 mm × 0.5076 mm) constituting the code pattern image formed on the print document 90 are simultaneously read. In the first imaging region S1, about 25 unit code patterns are read simultaneously. That is, the first imaging area S1 is slightly wider than the code block shown in FIG. 5, and almost one code block is read by one imaging. In the following description, data obtained by reading a code pattern image with the infrared CMOS 64 is referred to as code image data.

FIG. 11 is a block diagram illustrating an example of the configuration of the control unit 61 provided in the digital pen 60.
The control unit 61 includes an overall control unit 611, a light emission control unit 612, a light reception control unit 613, and an image processing unit 614.
The overall control unit 611 controls the light emission control unit 612, the light reception control unit 613, and the image processing unit 614 based on a signal input from the writing pressure detection switch 62. The overall control unit 611 controls the light emission control unit 612 based on switching information (described later) input from the image processing unit 614. The light emission control unit 612 as an example of the switching unit and the lighting instruction unit controls the light emission operation of the first infrared LED 63a and the second infrared LED 63b constituting the infrared LED 63 based on an instruction received from the overall control unit 611. . Specifically, based on switching information input via the image processing unit 614, control is performed to selectively turn on either the first infrared LED 63a or the second infrared LED 63b. The light reception control unit 613 as an example of the light reception instruction unit controls the light reception operation of the infrared CMOS 64 based on the instruction received from the overall control unit 611. The image processing unit 614 performs image processing on the code image data input from the infrared CMOS 64 based on the instruction received from the overall control unit 611, and outputs the obtained result to the communication circuit 66 and the overall control unit 611. .
In the present embodiment, the infrared CMOS 64 performs imaging at a frame rate of 60 to 100 times / sec. Further, the first infrared LED 63a or the second infrared LED 63b constituting the infrared LED 63 blinks at 60 to 100 times / sec in synchronization with the imaging timing of the infrared CMOS 64. The encoded image data acquired at each imaging timing is sent to the image processing unit 614 one by one.

  FIG. 12 is a block diagram illustrating an example of the configuration of the image processing unit 614 of the control unit 61 illustrated in FIG. An image processing unit 614 as an example of an acquisition unit includes an image acquisition unit 91, a noise removal unit 92, a binarization processing unit 93, a dot position detection unit 94, a reference dot pair detection unit 95, and an angle detection unit. 96, a decoding unit 97, and a whiteout detection unit 98. Here, the reference dot pair detection unit 95 includes a proximity dot pair detection unit 95a and a dot pair selection unit 95b. The decoding unit 97 includes a synchronization unit 97a, a unit code pattern boundary detection unit 97b, a synchronization code detection unit 97c, an identification code detection unit 97d, an RS code decoding unit 97e, a position code detection unit 97f, A position code decoding unit 97g. Further, the whiteout detection unit 98 includes a dot whiteout detection unit 98a, a background whiteout detection unit 98b, and a light source switching determination unit 98c.

The image acquisition unit 91 acquires code image data obtained by reading a code pattern image with the infrared CMOS 64 (see FIG. 8). In the present embodiment, the image acquisition unit 91 acquires code image data of the entire imaging region S (see FIG. 10).
And the noise removal part 92 extracts while extracting the code image data imaged in 1st imaging area S1 (refer FIG. 10) among the code image data of the whole imaging area S which the image acquisition part 91 acquired. Processing for removing noise (variation in sensitivity of the infrared CMOS 64 (imaging device) and noise generated by an electronic circuit) included in the encoded image data is performed. In addition, examples of the noise removal processing include sharpening processing such as blurring processing and unsharp masking.

  The binarization processing unit 93 separates the code image data into a dot image and a background image by binarization processing. Then, the dot position detection unit 94 detects a dot formation position (hereinafter referred to as a dot position) in the code pattern image from the binarized individual dot images. However, since a binarized dot image may contain many noise components, it is determined whether the dot image is a dot image based on the area and shape of the binarized dot image before detecting the dot position. It is preferable to combine the filtering processes to be performed.

The proximity dot pair detection unit 95a in the reference dot pair detection unit 95 refers to the dot position detected by the dot position detection unit 94, for example, and forms a pair (proximity dot pair) with the closest dot position from each dot position. .
Further, the dot pair selection unit 95b selects a reference dot pair from among a plurality of generated adjacent dot pairs, for example. Here, the reference dot pair refers to a dot pair having a particularly short inter-dot distance among a plurality of adjacent dot pairs.
Then, the angle detector 96 detects the rotation angle of the code pattern image based on the selected reference dot pair, for example.

The decoding unit 97 as an example of an output unit outputs predetermined information (identification information and position information) included in the code pattern image based on, for example, information such as the received dot position and rotation angle.
In the decoding unit 97, the synchronization unit 97a synchronizes the dot position on the two-dimensional array with reference to, for example, the detected dot position, the rotation angle, and the inter-dot distance of the reference dot pair. Here, “synchronize” means, for example, a process in which a position where a dot is present on a two-dimensional array is replaced with 1 and a position where a dot is not present is replaced with 0, etc. I mean.

Then, the unit code pattern boundary detection unit 97b detects the boundary of the unit code pattern constituting the code block from the dot positions synchronized on the two-dimensional array, for example. Specifically, for example, on the two-dimensional array output by the synchronization unit 97a, a rectangular separation position having the same size as the unit code pattern is appropriately moved, and the position where the number of dots included in the separation becomes equal is a unit. It is detected as the boundary position of the code pattern. Also, if the number of equalized dots is 2, a code pattern in which information is embedded with a unit code pattern of ₉ C ₂ , and if the number of dots is 3, information is embedded in a unit code pattern of ₉ C ₃ An information embedding method may be determined such as a code pattern.

  In addition, the synchronization code detection unit 97c detects the synchronization code with reference to the type of each unit code pattern detected from the two-dimensional array, for example. The synchronization code detector 97c detects the direction of the code pattern (in units of 90 degrees) and corrects it depending on which of the four types of synchronization codes (see FIG. 4) is detected.

Furthermore, the identification code detection unit 97d acquires the identification code from the code pattern whose angle is corrected with reference to the position of the synchronization code.
Furthermore, the RS code decoding unit 97e decodes the identification code detected using the same parameters (such as the number of blocks) used in the RS code encoding process, and outputs the obtained identification information.

On the other hand, the position code detection unit 97f acquires a position code from the code pattern whose angle is corrected with reference to the position of the synchronization code.
Then, the position code decoding unit 97g extracts the M series partial sequence from the position code acquired by the position code detection unit 97f, refers to the position of the detected partial sequence with respect to the M sequence used for image generation, The position offset information is corrected as position information (because the synchronization code is arranged between the position codes) and is output as position information.

The whiteout detection unit 98 detects, for example, the occurrence of whiteout in the code image data of the entire imaging region S acquired by the image acquisition unit 91 and turns on the infrared LED 63 (first infrared light) according to the detection result. Switching information for instructing switching of the LED 63a and the second infrared LED 63b) is output.
The dot whiteout detection unit 98a of the whiteout detection unit 98 uses the code image data of the entire imaging region S to detect whiteout (“dots” caused by regular reflection light from dots formed on the medium constituting the print document 90. The occurrence state of whiteout) is detected.
Similarly, the background whiteout detection unit 98b generates whiteout (referred to as “background whiteout”) caused by specularly reflected light from the medium constituting the print document 90, that is, the background, from the code image data of the entire imaging region S. Is detected.
The light source switching determination unit 98c is turned on based on the dot whiteout occurrence state detected by the dot whiteout detection unit 98a and the background whiteout occurrence state detected by the background whiteout detection unit 98b. The switching information (first infrared LED 63a or second infrared LED 63b) is determined and output.

  These functions are realized by cooperation between software and hardware resources. Specifically, the CPU (not shown) of the image processing unit 614 reads a program that realizes the function of each unit constituting the image processing unit 614 from, for example, a storage device such as an EEPROM into the information memory 65 and executes the program. The function of is realized. Further, the program and data stored in the EEPROM or the like may be loaded from a recording medium such as a CD or downloaded via a network such as the Internet.

Here, “dotted whiteout” and “background whiteout” described above will be described in more detail.
FIG. 13 is a diagram illustrating an example of the relationship between the infrared LED 63 to be lit and the distribution of reflected light from the print document 90 when the axis of the digital pen 60 is inclined at a predetermined angle in the α direction with respect to the print document 90. is there. Here, FIG. 13A shows a case where the first infrared LED 63a is turned off and the second infrared LED 63b is turned on, and FIG. 13B shows that the first infrared LED 63a is turned on and the second red LED 63b is turned on. A case where the outer LED 63b is turned off is shown.

  In the present embodiment, the printed pattern 90 is irradiated with infrared light by the first infrared LED 63a or the second infrared LED 63b, and the reflected light is received by the infrared CMOS 64, thereby reading the code pattern image. ing. Here, the reflected light from the printed document 90 includes regular reflected light reflected at the same reflection angle as the irradiation angle (incident angle) of infrared light with respect to the printed document 90 and diffuse reflection reflected at various reflection angles. There is light. At this time, the intensity of the regular reflection light from the printed document 90 tends to be higher than that of the diffuse reflection light.

For example, in the state shown in FIG. 13A, the specularly reflected light that is emitted from the second infrared LED 63 b and reflected by the print document 90 is incident on the infrared CMOS 64. In such a case, in the infrared CMOS chip 641 that has received the specularly reflected light, the output of the cell is saturated due to an excessive amount of light, and “whiteout” occurs in the obtained code image data. As a result, it becomes difficult to acquire identification information and position information from code image data obtained by reading a code pattern image. At this time, when the specularly reflected light from the dots formed on the printed document 90 is incident on the infrared CMOS 64, the dot whiteout occurs, and the specularly reflected light from the medium constituting the printed document 90 is incident on the infrared CMOS 64. When incident, background whiteout occurs. These may occur independently or in combination of both.
On the other hand, for example, in the state shown in FIG. 13B, diffused reflected light that is emitted from the first infrared LED 63 a and reflected by the print document 90 is received by the infrared CMOS 64. In such a case, the above-described whiteout is unlikely to occur, and therefore it becomes easy to obtain identification information and position information from the code pattern image.

  Further, according to the experiment by the present inventor, it has been found that the intensity of specularly reflected light increases within an angle range of ± 5 degrees. For this reason, in the present embodiment, as described with reference to FIG. 9, the first angle θ <b> 1 formed by the first illumination optical axis and the light receiving axis from the first infrared LED 63 a toward the reading position R and the second angle are set. The sum of the second angle θ2 formed by the second illumination optical axis and the light receiving axis from the infrared LED 63b toward the reading position R is set to 10 degrees or more. Thus, for example, as shown in FIG. 13B, even when the first infrared LED 63a is turned on with the axis of the digital pen 60 tilted in the α direction, the regular reflected light from the printed document 90 is not generated. It does not enter the infrared CMOS 64.

  FIG. 14A shows an example of code image data when dot whiteout occurs, and FIG. 14B shows an example of code image data when background whiteout occurs. The actual code image data is a numerical string in which each pixel is represented by an output value of 8 bits (0 to 255), but here, it is shown in two dimensions and light and dark for easy understanding.

  As shown in FIG. 14A, when dot whiteout occurs, the output value corresponding to such a dot is higher (brighter) than the background. Here, FIG. 14A also shows dots where no whiteout occurs, but the output value corresponding to such dots is lower (darker) than the background. In this embodiment, since dots are formed using black toner, the infrared light irradiated on the print document 90 is absorbed by the dots, and as a result, the output value corresponding to the dots is the background. Should be lower. However, when the infrared CMOS 64 receives regular reflection light from a dot, the output value corresponding to the dot is higher than the background. Such dot whitening is likely to occur when a code pattern image is formed using toner with high glossiness.

  On the other hand, as shown in FIG. 14B, when background whiteout occurs, the output value corresponding to the background becomes significantly higher (brighter) than the example shown in FIG. The output value corresponding to the dot is slightly lower (darker) than the background, but the difference between the output value of the background and the dot is small and the dot is buried in the background. Note that such background whiteout tends to occur when a medium having high glossiness such as coated paper is used.

  15A shows an example of dots for one line in the X direction formed on the print document 90. FIGS. 15B to 15D show red dots for one line in the X direction shown in FIG. Coded image data obtained by reading with the outer CMOS 64 is shown. However, FIG. 15B shows a case where no dot whiteout and background whiteout occur, FIG. 15C shows a case where dot whiteout occurs, and FIG. 15D shows a case where background whiteout occurs. Are illustrated respectively. 15B to 15D, the horizontal axis is the pixel number in the X direction, and the vertical axis is the output value at each pixel. Here, in FIGS. 15B to 15D, the output value corresponding to the background has an arcuate shape. This is the amount of infrared light emitted from the digital pen 60 to the print document 90. However, it is because it is large at the center in the X direction and small at the end. However, the digital pen 60 performs level correction so that the output value from the background is in the vicinity of the median value of 128 by executing so-called automatic exposure before starting the reading operation of the code pattern image. Yes.

  As shown in FIG. 15B, when whiteout does not occur, in the obtained code image data, the output value corresponding to each dot is lower than the background. In the present embodiment, binarization is performed by the binarization processing unit 93 (see FIG. 12) as preprocessing for decoding the identification information and position information from the encoded image data by the decoding unit 97 (see FIG. 12). . When such code image data is obtained, the background image and the dot image are favorably separated by performing binarization processing using a threshold value indicated by a one-dot chain line in the drawing, for example.

  On the other hand, as shown in FIG. 15C, when dot whiteout occurs, the output value corresponding to the dot where whiteout does not occur in the obtained code image data is lower than the background, but whiteout occurs. The output value corresponding to the dot where the occurrence has occurred becomes higher than the background. When such dot whiteout occurs, even if binarization processing is performed using the threshold value indicated by the alternate long and short dash line in the figure, the background image and the dot image cannot be separated in the right region in the figure, All of this area will be recognized as a background image.

  On the other hand, as shown in FIG. 15D, when background whiteout occurs, in the obtained code image data, the output values corresponding to the background and dots are almost saturated in the area where background whiteout occurs. End up. When such background whiteout occurs, even if binarization processing is performed using the threshold shown in the figure, the background image and the dot image cannot be separated in the right area in the figure. All will be recognized as a background image.

Here, in the present embodiment, an error occurring when reading a code pattern image is assumed, and an error correction code is included in the unit code pattern in advance. For this reason, even if the above-described dot whiteout or background whiteout occurs at a rate of about several percent in the code image data, for example, there is no particular problem in decoding of identification information and position information. However, for example, when whiteout occurs at a higher rate, decoding may be difficult.
Therefore, in the present embodiment, the whiteout detection unit 98 detects the occurrence state of such dot whiteout and background whiteout, and switches the infrared LED 63 to be turned on as necessary, thereby correcting the normality of the infrared CMOS 64. The incidence of reflected light and the occurrence of whiteout associated therewith are avoided.

Now, various processes executed by the whiteout detection unit 98 of the image processing unit 614 shown in FIG. 12 will be described in detail.
FIG. 16 is a flowchart showing a flow of processing executed by the dot whiteout detection unit 98a of the whiteout detection unit 98.
In this process, first, the dot whiteout detection unit 98a acquires code image data of the entire imaging region S from the image acquisition unit 91 (step 101). Next, the pixel number N is set to 1 (step 102), and the output average value S _NAve of the peripheral pixels including the output value S _N of the _Nth pixel (referred to as the _target pixel _PN ) is obtained (step 103). Note that the output value _SN has 8 bits, that is, any value from 0 to 255 as described above. Then, it is determined whether or not the output value S _N of the _target pixel P _N is equal to or _larger than the value obtained by adding 20 to the output average value S _NAve obtained in Step 103 (S _N ≧ S _NAve +20) (Step S 104). Note that “S _NAve +20” is a threshold for determination in dot _whiteout detection (referred to as dot _whiteout threshold). If an affirmative determination is made, the pixel of interest _PN is stored in a memory (not shown) as an overexposed pixel, that is, an abnormal pixel (step 105). On the other hand, if a negative determination is made, the process proceeds to step 106 as it is. Then, it is determined whether or not the processing has been completed for all pixels, that is, 22,500 pixels (step 106). If the processing has not been completed, N is set to N + 1 (step 107), and the processing returns to step 103 for the next attention. to continue the above-described process on the pixel P _N.
If it is determined in step 106 that the processing for all the pixels has been completed, then the abnormal pixels stored in step 105 are read from a memory (not shown), and this is two-dimensionally matched to the cell arrangement in the infrared CMOS chip 641. Arrange (step 108). Then, abnormal dots are detected from abnormal pixels arranged two-dimensionally (step 109), the number of detected abnormal dots is counted (step 110), and the obtained abnormal dot count value C is switched to the light source. An output is made toward the determination unit 98c (step 111), and a series of processing is completed.

FIG. 17 is a flowchart showing the flow of processing executed by the background whiteout detection unit 98b of the whiteout detection unit 98.
In this process, first, the background blanking detection unit 98b acquires code image data of the entire imaging region S from the image acquisition unit 91 (step 201). Next, the pixel number N is set to 1 (step 202), and the output value S _N of the pixel of interest _PN which is the _Nth pixel is extracted (step 203). Then, it is determined whether or not the output value S _N of the target pixel P _N is equal to or greater than the background whiteout threshold S _Th read from a memory (not shown) (S _N ≧ S _Th ) (step 204). If an affirmative determination is made, the target pixel _PN is counted as an abnormal pixel (step 205) and written in a memory (not shown). On the other hand, if a negative determination is made, the process proceeds directly to step 206. Then, it is determined whether or not the processing has been completed for all pixels, that is, 22,500 pixels (step 206). If the processing has not been completed, N is set to N + 1 (step 207), and the processing returns to step 203 for the next attention. to continue the above-described process on the pixel P _N.
If it is determined in step 206 that the processing for all the pixels has been completed, then the abnormal pixel count value D counted in step 205 is read from the memory and output to the light source switching determination unit 98c (step 208). Complete the process.

FIG. 18 is a flowchart showing a flow of processing executed by the light source switching determination unit 98c.
In this process, first, the light source switching determination unit 98c acquires the abnormal dot count value C from the dot whiteout detection unit 98a (step 301), and also obtains the abnormal pixel count value D from the background whiteout detection unit 98b. Obtain (step 302). The abnormal dot count value C and the abnormal pixel count value D acquired at this time are obtained from the same code pattern image. Subsequently, it is determined whether or not the abnormal dot count value C acquired in step 301 is equal to or greater than the threshold C _{0 of the} number of abnormal dots read from a memory (not shown) (C ≧ C ₀ ) (step 303). Note that the threshold C ₀ for the number of abnormal dots is set to 6, for example. As described above, the number of unit code patterns that can be imaged at one time in the imaging region S of the infrared CMOS chip 641 is about 64, and the number of unit images included in each unit code pattern is two. Therefore, the number of unit images that can be imaged at one time in the imaging region S is about 128, and when the rate of hindrance to decoding is 5% or more, the number corresponding to 5% is about 6. Because.

If a negative determination is made in step 303, then the abnormal pixel count value D acquired in step 302 is equal to or greater than the threshold D _{0 of the} number of abnormal pixels read from a memory (not shown) (D ≧ D ₀ ). It is determined whether or not (step 304). Note that the threshold D ₀ of the number of abnormal pixels is set to 1125, for example. This is because the number of pixels that can be imaged at one time in the imaging region S of the infrared CMOS chip 641 is 22500, and when the rate of hindrance to decoding is 5% or more, the number corresponding to 5% is 1125. This is because it becomes an individual. If a negative determination is made in step 304, the process proceeds to step 306.

On the other hand, when an affirmative determination is made in step 303 or step 304, the infrared LED 63 that is currently lit in the digital pen 60 (for example, the first infrared LED 63a) is replaced with the other (in this case, the second infrared LED 63a). A lighting switching instruction for switching to the LED 63b is output as switching information (step 305). In response to this, for example, the light emission control unit 612 performs control to turn off the first infrared LED 63a that is currently turned on and turn on the second infrared LED 63b that is currently turned off. When the second infrared LED 63b is turned on, the light emission control unit 612 performs control to turn off the second infrared LED 63b that is currently turned on and turn on the first infrared LED 63a that is currently turned off. Do.
Thereafter, it is determined whether or not the writing operation is finished (step 306). When the writing operation is finished, a series of processing is completed. On the other hand, when the writing operation is continued, the process returns to step 301 to continue the processing.

FIG. 19 is a diagram illustrating an example of processing in the dot whiteout detection unit 98a illustrated in FIG. Here, FIG. 19A is for explaining the processing in steps 103 to 105 shown in FIG. FIG. 19B is for explaining the processing in steps 108 to 109 shown in FIG. FIGS. 19A and 19B show a part (100 pixels: X _{a to} X _{a + 9} , Y _{b to} Y) of the obtained code image data (22500 pixels) of the entire imaging region S. _{b + 9} ). And the numerical value displayed on each square represents the output value of each cell.

In step 103, the dot _whiteout detection unit 98a obtains the output average value S _NAve of the peripheral pixels including the output value S _N of the _target pixel P _N. For example, assume that the pixel of interest P _N is a pixel (output value S _N : 241) located at the coordinates of (X _{a + 4} , Y _{b + 6} ). In the figure, the pixel of interest _PN is surrounded by a thick frame. Then, the dot overexposure detection unit 98a calculates an average output value S _Nave of 5 × 5 = 25 pieces of peripheral pixels around the pixel of interest P _N. In the figure, it indicated surrounded by a thin bold frame than the peripheral pixels a target pixel P _N. In this example, the output average value S _NAve is about 137. Subsequently, in step 104, the dot _whiteout detection unit 98a determines that the output value S _N = 241 of the pixel of interest P _N is obtained by adding 20 to the obtained output average value S _NAve = 137. It is judged whether it is above. In this case, since the output value S _N of the target pixel P _N is equal to or greater than the dot whiteout threshold, it is determined in step 105 that the pixel is an abnormal pixel. Incidentally, for example, the lower of _{(X a + 4, Y b} + 6) (X a + 4, Y b + 5) pixel located at (output value S _N: 140) when the pixel of interest P _N, since the output value S _N of the target pixel P _N is less than the dot overexposure threshold, the pixel will be determined not to be abnormal pixel.
Incidentally, it is shown in the determination of the detection skipping dots white, you are creating an average output S _Nave jumping dot white threshold value using the peripheral pixels around the pixel of interest P _N also for example FIG. 15 (c) As described above, the output value from the background region varies depending on the position of the cells constituting the infrared CMOS chip 641.

In step 108, the abnormal pixels obtained by the above-described procedure are two-dimensionally arranged. Then, as shown in FIG. 19B, a place where a plurality of abnormal pixels are arranged adjacent to each other occurs. In FIG. 19B, abnormal pixels are indicated by halftone dots. In step 109, a location where a plurality of abnormal pixels are arranged adjacent to each other is detected as one abnormal dot. In the present embodiment, this is because one dot (φ about 100 μm) formed in the printed document 90 is set larger than the reading area (about 26 μm × about 26 μm) of one cell constituting the infrared CMOS chip 641. This is because one dot is actually read by a plurality of cells. In this embodiment, abnormal pixels that are not adjacent to other abnormal pixels (for example, pixels located at the coordinates of (X _{a + 3} , Y _{b + 4} )) are not detected as abnormal dots. This takes into account errors in reading. Accordingly, in the example shown in FIG. 19 (b), the portion surrounded by the broken line, that is, three abnormal dots are detected and counted.

FIG. 20 is a diagram illustrating an example of processing in the background whiteout detection unit 98b illustrated in FIG. Here, FIG. 20A shows a part (100 pixels: X _{a to} X _{a + 9} , Y) of the code image data (22500 pixels) of the entire imaging region S acquired in step 201 shown in FIG. _{b to} Y _{b + 9} ). FIG. 20B is for explaining the processing in steps 204 to 205 shown in FIG.

In step 204, the background white skipping detecting section 98b is, the output value S _N of the target pixel P _N is determined whether the background overexposed threshold S _Th or more. In the above-described dot _whiteout determination process, the dot _whiteout threshold is determined from the output average value S _{NAve for} each pixel, but here, a uniform value is used, and the background _whiteout threshold S _Th is, for example, 220.
In step 205, the target pixel _PN determined to be an abnormal pixel is counted as an abnormal pixel. Here, in FIG. 20B, abnormal pixels are indicated by halftone dots. Thus, in the example shown in FIG. 20B, a total of 11 abnormal pixels are detected and counted.
In the determination of the background whiteout detection, the background whiteout threshold value S _Th is set to a constant value. For example, as shown in FIG. This is because the output value due to background whiteout becomes large to such an extent that the variation in output value from can be ignored.

  By the way, in this embodiment, code image data imaged in the first imaging region S1 of the infrared CMOS chip 641 is used for decoding identification information and position information, and red for detecting dot whiteout and background whiteout. Coded image data imaged in the imaging area S (first imaging area S1 + second imaging area S2) of the outer CMOS chip 641 is used. Next, the reason will be described.

  FIG. 21 is a diagram for explaining the relationship between the tilt of the digital pen 60 with respect to the print document 90 and the incidence of specularly reflected light on the infrared CMOS 64. 21A shows a state in which the axis of the digital pen 60 is in the W direction, that is, perpendicular to the print document 90, and FIG. 21B shows the digital pen 60 from the state shown in FIG. 21 (c) shows a state where the axis of the digital pen 60 is further inclined in the α direction from the state shown in FIG. 21 (b). In this example, it is assumed that the first infrared LED 63a is turned off and the second infrared LED 63b is turned on.

In the state shown in FIG. 21A, the specularly reflected light emitted from the second infrared LED 63b and reflected by the print document 90 is not directed toward the infrared CMOS 64, and the infrared CMOS 64 is not transmitted from the print document 90. Diffuse reflected light is incident. On the other hand, in the state shown in FIG. 21B, as the axis of the digital pen 60 is tilted in the α direction, the specularly reflected light from the print document 90 is changed to the X direction end portion side of the infrared CMOS 64 (FIG. 10). (Refer to Ref.) In the state shown in FIG. 21 (c), as the axis of the digital pen 60 is further tilted in the α direction, the specularly reflected light from the print document 90 is centered in the X direction of the infrared CMOS 64 (see FIG. 10). Is incident.
From the above, it can be seen that as the axis of the digital pen 60 is tilted in one direction with respect to the print document 90, the specularly reflected light from the print document 90 begins to enter from the end side of the infrared CMOS 64. Here, the case where the axis of the digital pen 60 is inclined in the α direction with respect to the print document 90 has been described as an example. However, for example, the axis of the digital pen 60 is inclined in the direction opposite to the α direction, or Even when the axis of the digital pen 60 is inclined toward the front side or the back side in the figure, the specularly reflected light from the printed document 90 starts to enter from the end side of the infrared CMOS 64 in the same manner.

Therefore, in the imaging region S of the infrared CMOS chip 641 shown in FIG. 10B, the specularly reflected light first enters the second imaging region S2 existing on the end side, and then exists in the center. The regularly reflected light is incident on the first imaging region S1.
For this reason, in the present embodiment, the dot whiteout and background whiteout are detected from the code image data acquired from the image pickup area S including the first image pickup area S1 and the second image pickup area S2. The infrared LED 63 to be lit is switched before whiteout occurs in the first imaging region S1 used for acquiring information and position information. Thereby, the whiteout is prevented from affecting the code image data acquired from the first imaging region S1.
In the present embodiment, detection of dot whiteout and background whiteout detection is performed from the code image data acquired in the imaging region S. For example, code image data acquired in the second imaging region S2 It is also possible to perform detection of dot whiteout and background whiteout only from the above.

  In the present embodiment, the digital pen 60 having the first infrared LED 63a and the second infrared LED 63b as the infrared LED 63 has been described. However, the present invention is not limited to this, and three or more infrared LEDs are used. Of course, it may be provided. In the case where three or more infrared LEDs are provided, for example, two infrared LEDs out of three may be controlled to be lit.

It is the figure which showed an example of the structure of the handwriting information management system of this Embodiment. It is an explanatory view of an example of a unit code pattern of the code pattern image _{(9 C 2).} It is a view showing a dot arrangement of the 36 types that can take the unit code pattern of ₉ C _2. It is a diagram showing a combination of synchronization code that can be selected from the dot arrangement of 36 types that can take the unit code pattern of ₉ C _2. It is the figure which showed an example of the code block for embedding a synchronous code, a position code, and an identification code. It is the figure which showed an example by which the position code is arrange | positioned in the code pattern image. It is the figure which showed an example by which the identification code is arrange | positioned in the code pattern image. It is a figure explaining the outline of a structure of a digital pen. It is the figure which looked at 1st infrared LED, 2nd infrared LED, and infrared CMOS which comprise a digital pen from the IX direction shown in FIG. It is a figure which shows an example of a structure of the infrared CMOS provided in the digital pen. It is the block diagram which showed an example of the structure of the control part provided in the digital pen. It is the block diagram which showed an example of the structure of the image process part of a control part. It is a figure for demonstrating the relationship between the inclination of the digital pen with respect to a printing document, the infrared LED to light, and the reflected light from a printing document. (A) is a figure which shows the example of the code image data in which the dot whiteout occurred, and (b) is the figure which shows the example of the code image data in which the background whiteout has occurred. (A) shows dots formed in a printed document, (b) shows code image data when no whiteout occurs, (c) shows code image data when a dot whiteout occurs, (d) shows It is a figure which respectively shows the code | cord | chord image data when a background whiteout arises. It is a flowchart which shows the flow of the process performed in the dot whiteout detection part of a whiteout detection part. It is a flowchart which shows the flow of the process performed in the background whiteout detection part of a whiteout detection part. It is a flowchart which shows the flow of the process performed in the light source switching determination part of a whiteout detection part. It is a figure which shows an example of the process in a dot white-out detection part. It is a figure which shows an example of the process in a background white-out detection part. It is a figure for demonstrating the relationship between the inclination of the digital pen with respect to a printing document, and incidence | injection of the regular reflection light to infrared CMOS.

Explanation of symbols

60 ... Digital pen, 61 ... Control unit, 611 ... Overall control unit, 612 ... Light emission control unit, 613 ... Light reception control unit, 614 ... Image processing unit, 62 ... Pen pressure detection switch, 63 ... Infrared LED, 63a ... No. 1 infrared LED, 63b ... 2nd infrared LED, 64 ... infrared CMOS, 91 ... image acquisition unit, 92 ... noise removal unit, 93 ... binarization processing unit, 94 ... dot position detection unit, 95 ... reference dot Pair detection unit, 96 ... angle detection unit, 97 ... decoding unit, 98 ... whiteout detection unit, 98a ... dot whiteout detection unit, 98b ... background whiteout detection unit, 98c ... light source switching determination unit

Claims (16)

A plurality of irradiation means for irradiating the medium on which the code image is formed;
A light receiving unit that receives reflected light from the medium irradiated with light by the irradiation unit when any of the plurality of irradiation units is turned on;
Obtaining means for obtaining the code image from a result of receiving the reflected light by the light receiving means;
A reading apparatus comprising: a switching unit that switches an irradiating unit that is turned on from the plurality of irradiating units according to a whiteout occurrence state in the light reception result of the reflected light by the light receiving unit. The plurality of irradiation means includes a first irradiation means and a second irradiation means for irradiating light toward the reading position of the medium by the light receiving means,
When the specularly reflected light that is irradiated by the first irradiating unit and reflected by the medium is incident on the reading unit, the specularly reflected light that is irradiated by the second irradiating unit and reflected by the medium is The reading apparatus according to claim 1, wherein an irradiation direction of light of each of the first irradiation unit and the second irradiation unit is set so as not to enter the reading unit. The plurality of irradiation means includes a first irradiation means and a second irradiation means for irradiating light toward the reading position of the medium by the light receiving means,
A first optical axis from the first irradiation means to the reading position and a second optical axis from the second irradiation means to the reading position are directed from the reading position to the light receiving means. 3. The reading apparatus according to claim 1, wherein the reading apparatus has a symmetrical positional relationship with respect to the third optical axis.   The switching unit detects the occurrence of the whiteout caused by an excessive amount of reflected light incident on the light receiving unit from the irradiation unit through the medium. 4. The reading device according to any one of items 3.   The switching means detects the occurrence of whiteout caused by specularly reflected light entering the light receiving means from the irradiation means via the medium. The reading device according to claim 1. The light receiving means includes a first imaging area configured by arranging a plurality of light receiving elements, and a second imaging area configured by arranging a plurality of light receiving elements on the periphery of the first imaging area. With a two-dimensional sensor,
The acquisition means acquires the code image from a light reception result received in the first imaging region of the two-dimensional sensor,
6. The reading according to claim 1, wherein the switching unit detects the occurrence of the whiteout from a light reception result received in the second imaging region of the two-dimensional sensor. apparatus.   The switching means is at least one of a whiteout occurrence state caused by reflected light from an image forming material constituting the code image on the medium and a whiteout occurrence state caused by reflected light from the medium. The reading apparatus according to claim 1, wherein:   The reading apparatus according to claim 1, further comprising writing means for writing on the medium. A medium on which a code image is formed;
In response to a user's writing operation on the medium, an electronic writing instrument that reads the code image from the medium;
Information for acquiring information related to the code image read by the electronic writing instrument and storing the writing content on the medium in association with the medium or an electronic document printed on the medium based on the acquired information A processing device,
The electronic writing instrument is:
Writing means for writing on the medium;
A plurality of irradiation means for irradiating the medium with light;
A light receiving unit that receives reflected light from the medium irradiated with light by the irradiation unit when any of the plurality of irradiation units is turned on;
Obtaining means for obtaining the code image from a result of receiving the reflected light by the light receiving means;
Transmitting means for transmitting the information related to the code image acquired by the acquiring means to the information processing apparatus;
A writing information processing system comprising: switching means for switching an irradiating means to be turned on from among the plurality of irradiating means in accordance with a whiteout occurrence state in the light reception result of the reflected light by the light receiving means. In the electronic writing instrument,
The switching means detects the occurrence of the whiteout caused by an excessive amount of reflected light incident on the light receiving means from any one of the irradiation means via the medium. Item 9. The written information processing system according to Item 9. In the electronic writing instrument,
The said switching means detects the generation | occurrence | production state of the said white-out resulting from specular reflection light injecting into the said light-receiving means via the said medium from any one of said irradiation means. Written information processing system. In the electronic writing instrument,
The light receiving means has a first area configured by arranging a plurality of light receiving elements and a second area configured by arranging a plurality of light receiving elements on the periphery of the first area. With
The acquisition means acquires the code image from a light reception result received in the first region of the two-dimensional sensor,
The writing information according to any one of claims 9 to 11, wherein the switching means detects the occurrence of the whiteout from a light reception result received by the second region of the two-dimensional sensor. Processing system. The electronic writing instrument further includes an output unit that acquires identification information of the medium or position information in the medium as the information related to the code image from the code image acquired by the acquisition unit and outputs the information to the transmission unit. Including
13. The information processing apparatus according to claim 9, wherein the information processing apparatus reads out an electronic document associated with the identification information and superimposes a writing locus corresponding to the position information on the electronic document. The writing information processing system according to claim 1. A lighting instruction means for lighting one of the light sources among a plurality of light sources that emit light to the medium on which the code image is formed;
A light receiving instruction means for receiving reflected light from the medium irradiated with light from the light source that is lit;
An acquisition means for acquiring the code image from a light reception result of the reflected light;
A control device for a reading apparatus, comprising: a switching instruction means for outputting an instruction to switch a light source to be turned on from among the plurality of light sources according to a state of occurrence of whiteout in the reflected light reception result. On the computer,
A function of turning on one of the light sources among a plurality of light sources that irradiate the medium on which the code image is formed;
A function of obtaining the code image from a light reception result of reflected light from the medium irradiated with light from the light source that is lit;
A program for realizing a function of switching a light source to be turned on from among the plurality of light sources according to a whiteout occurrence state in the light reception result. In the computer,
The program according to claim 15, further realizing a function of acquiring predetermined information embedded in the code image from the acquired code image.

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