JP2005070944A - Pad for pen type input device, and information input system comprised of the pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a detection marker printed on the surface of a pad visually inconspicuous, in a pen type input device and the pad that is the writing object of the device, although the marker can be precisely detected by the pen type input device. <P>SOLUTION: The pad 11 comprises a tough board 17 poor in flexibility as a base body. The detection marker 14 is formed on the surface of the board 17 by use of infrared absorbing ink. Otherwise, a film 18 having the detection marker 14 printed thereon may be stuck to the board 17. The color difference between the printed part by ink (detection marker 14) and a non-printed part 15 (ΔE*<SB>ab</SB>(p-p)) is set to 60 or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pad for a pen-type input device capable of transmitting handwritten information such as characters and figures written on the surface of a pad to an electronic device such as a mobile phone, a PDA, or a personal computer, and the pad The present invention relates to an information input system including a pen-type input device as a constituent element.

  In Patent Document 1, when a dedicated attachment is attached to a sheet such as A4 and characters are written on the sheet with a dedicated pen, the attachment calculates the pen position based on the ultrasonic wave transmitted by the pen, and the sheet There is described an information input system capable of reading characters and the like written on the above and transmitting writing information related to the read characters and the like as digital data to a personal computer or the like at any time. However, this system can output handwritten information to a personal computer only in real time. That is, there is a disadvantage in that the writing information of characters previously written on the whiteboard with the dedicated pen cannot be output to the personal computer even if the attachment is attached to the board later.

  Patent Document 2 discloses an information input system using a pen-type input device. Such an information input system includes a writing unit for writing characters, a camera unit having infrared irradiation ability, a storage unit including a storage unit, and a pen-type input device including a communication unit including a Bluetooth transceiver or a USB port, A board for inputting written contents to the pen-type input device is a constituent element. The board here is a white board or a plastic film attached on the board, and a detection pattern made up of a large number of independent minute dots is printed on the surface thereof. Then, when characters or figures are written on the board or film using the writing unit of the pen-type input device, the camera unit specifies the writing content based on the detection marker and stores it in the storage unit. The writing information in the storage unit can be appropriately sent to other electronic devices such as a personal computer via the communication unit.

  Patent Documents 3 to 5 show a sheet on which a detection marker for detecting a written content such as a position of a written character and a writing direction by a camera unit of a pen-type input device is printed.

Japanese translation of PCT publication No. 2002-508101 (FIG. 1) JP-T-2003-508831 (Claims 1, 2, paragraph 0009, paragraph 0987, paragraph 0088, symbol 6 in FIG. 1, FIG. 6) Japanese translation of PCT publication No. 2003-500777 (paragraph number 0083-0087, FIG. 3) JP-T-2003-500778 (paragraph number 0057-0059, FIG. 1) Japanese translation of PCT publication No. 2003-503905 (paragraph number 0050-0051, FIG. 1)

  In the information input system described in Patent Document 2, since all information written on a board or the like is stored in the pen-type input device, information can be sent to the personal computer in a lump. Compared to the information input system according to Patent Document 1 described above, it is superior in practical convenience in that the output to the PC is not limited to real time and it is not necessary to always connect a personal computer or the like and a pen-type input device. ing. Further, as described in Patent Documents 3 to 5, in the form in which the paper on which the detection marker is printed is used as the writing target of the pen-type input device, these papers cannot be repeatedly used because they are disposable, and the running cost is very high. On the other hand, in the form in which a plastic board or film is used for writing as in Patent Document 2, the board or film can be used repeatedly, which is advantageous in that the running cost can be reduced.

  However, when the detection marker is provided on the surface of the board or film as described above, it is important that the detection sensitivity of the pen-type input device camera is ensured. For this reason, in the above-mentioned document 2, a black or dark blue detection marker is provided on the surface of a board or the like, and the infrared ray absorption by the dot is detected by the camera of the pen-type input device, so that the pen position and the written content can be determined Although identified, there is a problem in that detection markers such as black are abnormally conspicuous and give the writer a great sense of incongruity (see Patent Document 2, paragraph number 0088).

  In addition, when writing with a pen on the surface of this type of board or the like, it is inevitable that ink bleed will occur when characters and the like are erased with an eraser. For this reason, the camera unit may mistakenly identify the ink residue as a dot, and the written content may not be accurately specified. In the worst case, a read error may occur.

  An object of the present invention is to provide a pad for a pen-type input device mainly composed of a tough and flexible plastic board, and a detection formed on the surface of the pad in an information input system using the pad as a component. The purpose of the present invention is to make the marker for use inconspicuous while it can be accurately detected with a pen-type input device. SUMMARY OF THE INVENTION An object of the present invention is to provide an information input system in which a camera unit does not mistakenly distinguish ink residue as a dot, and therefore, the written content can be accurately specified and read.

The present invention is directed to a pad 11 for inputting writing content to a pen-type input device P (see FIG. 3) as shown in FIG. As shown in FIG. 2, the pad 11 is provided with a tough plastic board 17 made of poor flexibility, and on the surface of the board 17, a camera of a pen-type input device P as shown in FIG. The detection marker 14 for detecting the written content in the part 4 is formed. The detection marker 14 is printed with an ink containing an infrared absorbing dye / pigment, and the L of the printed portion (detection marker 14) and the non-printed portion 15 with the ink calculated by the following mathematical formula 1. ^* a ^* b ^{* The} color difference ΔE ^* _ab (pp) based on the color system is 60 or less.
[Formula 1]

  In the present invention, the “infrared absorbing dye / pigment” means a dye or pigment having infrared absorbing ability. “The detection marker for detecting the written content by the camera unit of the pen-type input device is formed on the surface of the board” only if the detection marker 14 is printed on the surface of the board 17 itself. As shown in FIG. 2, the concept includes a form in which a film 18 on which a detection marker 14 is printed is attached to the surface of the board 17.

  A specific example of the pen-type input device P is a digital pen developed by Anoto, Sweden. As shown in FIG. 1, the detection markers 14 are composed of a large number of independent dots 12, and are distributed and arranged within a writable range on the board. These dots 12 are arranged according to a predetermined rule, and the position (coordinates) on the pad 11 is specified from this arrangement relationship. That is, the dots 12 are formed in a pattern for indicating the position on the pad 11. A specific example of such a dot pattern is a so-called Anoto pattern according to the Anoto standard. Examples of the method for forming the detection marker 14 include various printing methods such as offset printing, screen printing, and ink jet printing. In FIG. 1, the dots 12 constituting the detection marker 14 are arranged in a matrix, but this schematically shows the Anoto pattern, and the actual pattern arrangement is slightly different from this. Different.

  Specific examples of the infrared absorbing dye / pigment include cyanine and phthalocyanine dyes and pigments. An ink containing this type of dye / pigment is advantageous in reducing the manufacturing cost of the pad 11 because a sufficient detection S / N ratio can be obtained even when the ink is diluted and printed. Since these dyes and pigments have an excellent infrared absorbing ability, even when the surface of the pad 11 is slightly soiled, the detection sensitivity of the pen-type input device can be kept good, which is also advantageous in that respect. is there.

  The resin constituting the board 17 and its thickness dimension are not particularly limited as long as the board 17 is strong and poor in flexibility. The color tone of the board 17 and the film 18 is preferably white, but is not limited thereto. The film 18 can be colorless and transparent or colored and transparent. The length and width dimensions of the board 17 and the film 18 can be standard dimensions such as A5, for example.

  The present invention also includes a pen-type input device P having a writing unit 2, a camera unit 4, a storage unit 6, and a communication unit 7 as shown in FIG. 3, and a pen-type input device P as shown in FIGS. The pad 11 for inputting written content is a constituent element, and the written content written on the surface of the pad 11 by the writing unit 2 is specified by the camera unit 4 and stored in the storage unit 6. The information input system which can send the electronic information concerning the written content memorize | stored in other electronic devices via the communication part 7 is made into object. The pad 11 is provided with a tough plastic board 17 made of plastic that lacks flexibility, and the surface of the board 17 is used for detection for detecting the written content by the camera unit 4 of the pen-type input device P. A marker 14 is formed. The pen-type input device P includes a pen ink for writing characters on the surface of the board 11, and is included in the maximum absorption wavelength of the dye contained in the pen ink and the ink forming the detection marker 14. The difference from the maximum absorption wavelength of the infrared absorbing dyed pigment is 80 nm or more. Here, “another electronic device” means a personal computer, a mobile phone, a PDA, or the like.

Further, the color difference ΔE ^* _ab (p) based on the L ^* a ^* b ^* color system between the printed portion (detection marker 14) of the pad 11 and the non-printed portion 15 of the pad 11 calculated by Equation 1 below. -P) is preferably 60 or less.
[Formula 1]

  In the present invention, the detection marker 14 printed on the surface of the board 17 constituting the pad 11 is replaced with the conventional black or dark blue ink, and the good sensitivity (by the camera unit 4 of the pen type input device P) ( It is formed using an ink containing an infrared absorbing dye / pigment having a (S / N ratio). Therefore, by adjusting the color tone and density of the infrared absorbing dye pigment itself so that the detection marker 14 is not conspicuous, it is possible to detect the conventional black color while ensuring good detection sensitivity by the pen-type input device P. The sensory discomfort experienced by the writer due to the marker being abnormally conspicuous, which is inevitable with the marker for use, can be minimized.

  In other words, in the embodiment provided with the detection marker made of the conventional black or dark blue ink, the marker 14 is detected from the S / N ratio based on the brightness difference between the non-printed portion 15 on the board 17 and the detection marker 14. Therefore, the ink for forming the marker 14 must be black, and it is inevitable that it is noticeable. On the other hand, in the pad 11 of the information input system according to the present invention, the infrared absorption dye is included in the ink forming the detection marker 14, and the difference in the infrared absorption amount between the non-printed portion 15 of the pad 11 and the marker 14. Since the detection by the camera unit 4 is performed based on the S / N ratio based thereon, the ink forming the marker 14 may not be black. Accordingly, the color tone and density of the infrared absorbing dye itself can be adjusted, and the color tone of the ink can be appropriately changed in accordance with the color tone of the board 17 and the film 18 so that the detection marker 14 is not noticeable. Specifically, for example, when the board 17 is white, if the detection marker 14 is formed of white, yellow, green, or transparent ink, the marker 14 is not noticeable. can do. Further, it is advantageous in that good detection sensitivity can be secured by the camera unit 4 of the pen-type input device regardless of the color tone of the ink. However, since the color tone of the ink depends on the ink thickness, basis weight and the like, the color tone of the ink itself is not limited to the above in the present invention.

If the color difference ΔE ^* _ab (pp) between the printed portion (dot 12 portion of the detection marker 14) and the non-printed portion 15 is digitized using the L ^* a ^* b ^* color system, it is originally written. The sense of discomfort experienced by the writer due to the presence of the detection marker 14 on the board 17 that is influenced by the taste (main feeling) of the person can be defined quantitatively. Specifically, if the color difference ΔE ^* _ab (pp) is 60 or less, the dots 12 of the detection marker 14 formed of ink are not conspicuous uniformly, and the sense of discomfort experienced by the writer can be reduced. That is, if the color difference ΔE ^* _ab (pp) is 60 or less, the writer can use it without inconvenience without feeling uncomfortable. When the color difference ΔE ^* _ab (pp) is about 40, it becomes difficult to visually recognize the dots 12 of the detection marker 14 and the writer feels no sense of incongruity. Further, when the color difference ΔE ^* _ab (pp) is about 20, the dots 12 of the detection marker 14 cannot be seen with the naked eye, and the writer does not even recognize the presence of the detection marker 14. On the other hand, when the color difference ΔE ^* _ab (pp) exceeds 60, the detection marker 14 is abnormally conspicuous and hesitates to use it as a writing target. From the above, the color difference ΔE ^* _ab (pp) is preferably 60 or less, more preferably 40 or less, and most preferably 20 or less. Note that the lower limit value of the color difference ΔE ^* _ab (pp) is zero, which means that the dot 12 portion and the ground portion of the board 17 are completely the same color.

  The size of each dot 12 constituting the detection marker 14 is several μm, and it is almost impossible to measure the dot 12 itself using a color difference meter. Therefore, in practice, as shown in FIG. 1, the solid printing unit 13 is formed with the ink constituting the detection marker 14, and the measurement value by the color difference meter of the solid printing unit 13 is printed according to the detection marker 14. The brightness and chromaticity of the part. However, it goes without saying that the ink thickness of the dots 12 and that of the solid printing unit 13 are completely matched. The solid printing unit 13 is provided for convenience in measuring the color tone of the dot 12 portion, and it goes without saying that the solid printing unit 13 is not an essential component of the invention.

  When writing on the board 17 with a pen-type input device and then erasing characters or the like written with an eraser, pen “ink residue” tends to remain on the surface of the pad 11. Then, when characters and the like are entered again in the same place with the “ink residue” remaining in this way, the camera unit 4 of the pen-type input device recognizes the “ink residue” as the dot 12 and erroneously writes the written contents. May be identified. In the worst case, a read error occurs. Therefore, as in the present invention, the maximum absorption wavelength difference between the dye that is the main component of the pen ink contained in the writing unit 2 of the pen-type input device and the infrared absorbing dye pigment contained in the ink forming the detection marker 14 is calculated. When the thickness is 80 nm or more, it is possible to prevent the “ink residue” from being mistaken as the dot 12, and thus it is possible to reliably prevent misrecognition of written content and reading errors.

  1 and 2 show a pad for a pen-type input device according to the present invention, and FIG. 3 shows a pen-type input device. As shown in FIG. 3, the pen-type input device P includes a case 1 having an outer shape similar to that of a general pen, a writing unit 2 including a writing pen provided at the tip of the case 1, A camera unit 4 facing the tip of the writing unit 2 through the opening 3 provided at the tip, a processor 5 for determining a handwriting in the writing unit 2 based on a detection data value from the camera unit 4, and handwriting data A storage unit 6 including a memory for storage, a communication unit 7 for communicating with an external device (another electronic device), a battery 8 as a power source, and the like are provided. The battery 8 corresponds to a small lithium ion battery or the like. The external device corresponds to a personal digital assistant (PDA), a computer, a mobile phone, or the like.

  The writing unit 2 includes a pen tip including pen ink, and can write characters, figures, and the like on the pad 11 as shown in FIG. The writing unit 2 includes a pressure sensor that detects pen pressure, and outputs the pen pressure data to the processor 5. As shown in FIG. 1, a detection marker 14 detected by the camera unit 4 is printed on the surface of the pad 11.

  The camera unit 4 includes a light emitting unit 9 including an LED that irradiates infrared light toward the pad 11, and an imaging element 10 such as a CCD or CMOS sensor that receives reflected light from the pad 11. When writing, the detection marker 14 located around the pen tip of the writing unit 2 is detected. The communication unit 7 communicates with an external device using radio waves, infrared rays, or the like, and is specifically a Bluetooth transceiver. The processor 5 binarizes the shooting screen of the camera unit 4 based on the infrared absorption level.

  As shown in FIG. 2, the pad 11 includes a flexible thin resin film 18 on which the detection marker 14 is printed, and a tough and poorly flexible wall bonded to the lower surface of the film 18. Board 17. Specifically, the board 17 is a flat molded product having a thickness of about 1 to 20 mm made of various resins such as hard vinyl chloride resin and polycarbonate. Therefore, it exhibits good rigidity. The film 18 is made of various resins such as soft vinyl chloride resin, PET film, silicon rubber, etc., and has a thickness dimension of about 50 to 200 μm. Prior to application to the board 17, the film 18 is used for detection. A marker 14 is printed. With the configuration as described above, since characters and the like can be written on the film 18 in a posture supported by the board 17, the pad 11 and the information input system are excellent in practical convenience.

  The detection marker 14 is composed of a large number of independent dots 12 and is distributed within the writable range of the pad 11, in this embodiment, within the writable range of the film 18. Each dot 12 is arranged according to a pattern (Anoto pattern) determined by Anoto Co., which is a manufacturer of a pen-type input device, and the position (coordinates) on the pad 11 is specified from the arrangement relationship of these dots 12. Is done. That is, the detection marker 14 is formed in a pattern for specifying the position on the pad 11. The diameter of each dot 12 is about 8 μm.

  The detection marker 14 is printed with an ink containing an infrared absorbing dye / pigment, that is, an ink containing a dye and / or a pigment having infrared absorbing ability. By including an infrared absorbing dye / pigment in the ink and optimizing the blending ratio, good sensitivity (S / N ratio) of the detection marker 14 to the camera unit 4 can be ensured. In particular, by using a white, yellow, or colorless dye / pigment, the color difference between the background color of the pad 11 (non-printed portion 15) and the detection marker 14 can be reduced, making the marker 14 inconspicuous. Therefore, the sense of incongruity felt by the writer can be kept as small as possible.

Specifically, the color difference ΔE ^* _ab (pp) between the marker 14 and the non-printing portion 15 obtained by using Equation 1 is set to be 60 or less. If it is less than the value, the detection marker 14 is not conspicuous, and the uncomfortable appearance can be made relatively small. If the color difference ΔE ^* _ab (pp) is 40 or less, it can be used without a sense of incongruity, and if it is 20 or less, its presence is hardly recognized. On the other hand, when the color difference ΔE ^* _ab (pp) exceeds 60, a certain habit is remembered for use as a writing target.

  There is a difference of at least 80 nm or more between the maximum absorption wavelength of the dye of the pen ink contained in the writing part 2 of the pen-type input device and the maximum absorption wavelength of the infrared absorption dye contained in the ink forming the detection marker 14 It is said. Thus, if the maximum absorption wavelength of both infrared rays is 80 nm or more, the camera unit 4 can discriminate the ink residue as the dot 12 and reliably prevent writing contents from being erroneously recognized or causing a reading error. Can do.

  The pad 11 can be a so-called tablet type as shown in FIG. Specifically, in FIG. 4, the board 17 is composed of a flat bottom surface portion to which the film 18 is attached and a frame portion formed on the periphery of the bottom surface portion, and a stepped square having a recessed central portion. It has a dish shape. The pad 11 of this form is superior in design and portability to the flat pad 11 as shown in FIG. 1, and is advantageous in that respect. In this embodiment as well, it goes without saying that the detection marker 14 may be directly printed on the portion exposed on the surface of the bottom surface of the board 17 without using the film 18.

  EXAMPLES Next, an Example is given and this invention is demonstrated in detail. However, the present invention is not limited to these examples.

<Example 1>
(Preparation of pad) Infrared absorbing pigment YKR-5010 (maximum absorption wavelength 850 nm) manufactured by Yamamoto Kasei Co., Ltd. and a printing varnish were dispersed with two rolls, and an offset ink containing 25% by weight of this pigment was prepared. In addition to this ink, UV curable printing resin (Medium S, T & K
TOKA) was added to adjust the pigment to 1.3% by weight to prepare a UV curable ink. This ink was offset printed on a soft vinyl chloride film 18 (A5 size), and a detection marker 14 was formed on the film 18. The arrangement pattern of the dots 12 constituting the detection marker 14 was specified by Anoto. At the same time, a solid printed portion 13 of 2 cm × 2 cm was formed in the margin on the film using such ink. The ink thickness of the dots 12 and the solid printing portion 13 was about 1 μm. After printing, the ink was cured with UV light having a wavelength of 255 nm using a UV lamp (manufactured by USHIO, UVH-800H). The film 18 on which the dots 12 were printed was pasted on the surface of a board 17 made of hard vinyl chloride having a thickness of 2 mm and A5 size, thereby producing a pad 11.

(Preparation of pen-type input device) A BX132 pigment (maximum absorption wavelength 700 nm) manufactured by Dainippon Ink & Chemicals, Inc. was dispersed in isopropanol, and a pen ink containing 50% by weight of this pigment was prepared. Using this pen ink, a pen-type input device P as shown in FIG. 3 was created. The camera unit 4 of the pen-type input device P includes a camera unit (part No. 965102-2-0100-2) of a personal digital pen manufactured by US Logitech Co., manufactured in accordance with the standard of Anoto. The maximum wavelength of the light emitting unit 9 is 850 nm.

<Example 2>
A pad 11 and a pen-type input device P were produced in the same manner as in Example 1 except that the pigment concentration of the infrared absorbing organic material YKR-5010 used in Example 1 was changed to 5% by weight.

<Example 3>
A pad 11 and a pen-type input device P were produced in the same manner as in Example 1 except that the pigment concentration of the infrared absorbing organic material YKR-5010 used in Example 1 was set to 10% by weight.

<Comparative example 1>
Using a black UV curable offset ink (“Toyo Ink Co., Ltd., FD Carton P Black)” generally called “black”, this is applied to a soft vinyl chloride film in the same manner as in Example 1. The offset marker 14 and the solid printing unit 13 were formed by offset printing. Other than that was carried out similarly to Example 1, and obtained the pad 11 and the pen-type input device P which concern on the comparative example 1. FIG.

<Comparative example 2>
40 parts by weight of UV curable printing resin (Medium S, manufactured by T & K TOKA) was added to 60 parts by weight of the black UV curable ink used in Comparative Example 1 to prepare an ink. Thereafter, in the same manner as in Example 1, the pad 11 and the pen-type input device P according to Comparative Example 2 were obtained.

<Comparative Example 3>
20 parts by weight of UV curable printing resin (Medium S, manufactured by T & K TOKA) was added to 80 parts by weight of the black UV curable ink used in Comparative Example 1 to prepare an ink. Thereafter, in the same manner as in Example 1, the pad 11 and the pen-type input device P according to Comparative Example 3 were obtained.

The colors of the solid printed portion 13 on the pad 11 and the non-printed portion 15 without the detection marker 14 produced in the above examples and comparative examples were measured with a color difference meter Gardner 680U manufactured by BYK, Germany. ^* a ^* b ^* Specified based on the color system. Further, the color difference ΔE ^* _ab (pp) between the two portions was calculated using the above-described Equation 1.

  In both the example and the comparative example, the characters written on the pad 11 could be easily erased with a tissue or the like. Therefore, after erasing the written character with the eraser, the character was written again in the portion where the character was erased on the pad 11, and it was investigated whether the pen-type input device P could identify and read the written character. This operation was repeated several times, and the number of reading errors that occurred was examined. Table 1 shows the above measurement results, color difference values, and test results.

In the forms of Examples 1 to 3, the detection marker 14 was hardly visually recognized on the pad 11, and the sensory discomfort was hardly felt. This is because it is preferable that the color difference (ΔE ^* _ab (pp)) between the printed portion (detection marker 14) and the non-printed portion 15 with the ink obtained from Equation 1 is 60 or less. The numerical significance of the invention (see claims 1 and 3) is also completely consistent. On the other hand, in the forms of Comparative Examples 1 to 3, the detection marker 14 on the pad 11 was noticeable abnormally and felt uncomfortable. This is the numerical significance of the present invention that the color difference (ΔE ^* _ab (pp)) between the printed portion (detection marker 14) and the non-printed portion 15 with ink exceeds 60 (claim). (See item 2 and claim 4).

  As shown in Table 1, in the forms of Comparative Examples 1 to 3, a reading error occurred from the fifth time. It is considered that the pen ink residue remaining on the pad 11 was mistakenly recognized as the dot 12.

Pad top view Pad profile side view Schematic configuration diagram of pen-type input device The perspective view of the pad concerning another embodiment

Explanation of symbols

2 Writing part 4 Camera part 6 Storage part 7 Communication part 11 Pad 12 Dot 14 Detection marker 15 Non-printing part 17 Board 18 Film

Claims (3)

A pad for inputting writing content to a pen-type input device,
This pad is provided with a tough and flexible plastic board, and on the surface of the board is formed a detection marker for detecting written contents with the camera part of the pen-type input device. And
The detection marker is printed with an ink containing an infrared absorbing dye / pigment,
The color difference ΔE ^* _ab (pp) based on the L ^* a ^* b ^* color system between the printed part and the non-printed part of the ink calculated by the following mathematical formula 1 is 60 or less. Pad for pen-type input device.
[Formula 1]

A pen-type input device including a writing unit, a camera unit, a storage unit, and a communication unit, and a pad for inputting writing content to the pen-type input device are constituent elements,
The writing content written on the surface of the pad by the writing unit is specified by the camera unit and stored in the storage unit, and the electronic information related to the writing content stored in the storage unit is transmitted to another electronic device via the communication unit. An information input system that can be sent to a device,
The pad is provided with a tough and flexible resin board, and on the surface of the board is formed a detection marker for detecting written contents with a camera unit of a pen-type input device. And
The pen-type input device includes pen ink for writing characters on the surface of the board,
An information input system, wherein a difference between a maximum absorption wavelength of a dye contained in the pen ink and a maximum absorption wavelength of an infrared absorbing dye / pigment contained in the ink forming the detection marker is 80 nm or more. The color difference ΔE ^* _ab (pp) based on the L ^* a ^* b ^* color system between the printed portion of the pad and the non-printed portion of the pad, calculated by the following formula 1, is 60 or less. Item 3. The information input system according to Item 2.
[Formula 1]

Images