WO2009069849A1

WO2009069849A1 - Method of compensating keyboard template coordinates of projection keyboard

Info

Publication number: WO2009069849A1
Application number: PCT/KR2008/000167
Authority: WO
Inventors: Jai-Young Ahn
Original assignee: D & T. Inc.
Priority date: 2007-11-26
Filing date: 2008-01-10
Publication date: 2009-06-04
Also published as: KR20090054143A; KR100907287B1

Abstract

The present invention relates to a method of correcting keyboard template coordinates of a projection keyboard. The methodincludes a scan step of capturing the image of the keyboard template when power is on and generating a captured image frame, a distortion comparison step of determining whether a distortion existsin the captured image frame by comparing the captured image frame and a previously stored reference image frame, a corrected coordinate value generating step of, if, as a result of the determination, the distortion exists in the captured image frame, generating a corrected coordinate value according to thedistortion of the captured image frame, a coordinate value change step of updating a previously stored reference coordinate value table to the corrected coordinate value, and a key recognition stepof recognizing a key input event based on the corrected coordinate value.

Description

METHOF OF COMPENSATING KEYBOARD TEMPLATE COORDINATES OF PROJECTION KEYBOARD

Technical Field

[1] The present invention relates to a method of controlling a projection keyboard, and more particularly, to a method of correcting keyboard template coordinates of a projection keyboard, in which it can correct a distortion between a reference keyboard template and a projected keyboard template, which occurs as a result of comparison between them, using a coordinate value of the reference keyboard template on the basis of the projected keyboard template. Background Art

[2] The use of the keyboards of personal computers, which are generally used today, is limited to fixed places such as homes or offices. There is a tendency that input devices, such as PDAs, mobile phones and PMPs which are representative portable electronic devices developed and commercialized as a portable type, force users to use inconvenient input methods because of its limitation due to the size of the products.

[3] In order to address and solve this problem, a projection keyboard (or a virtual keyboard) has beendeveloped. The projection keyboard is an efficient interface machine, which is necessitated as the electronic devices are miniaturized and portable, is designed to use without limitations to the size or place, and can transfer intentions between the electronic devices and users.

[4] This projection keyboard is adapted to form a keyboard template (or a keypad) using a visible ray, determine a place where a user's hands are placed when the user's hands are placed at a specific area of the keyboard template, decide a character to be input by the user based on the determination result, and display a decided character.

[5] Referring to FIG. 1, a projection keyboard 10 includes a projection module 11, an

Infra Red (IR) module 13, a sensor module 15 and a controller 17.

[6] The projection module 11 projects a previously designed keyboard template 20 on a surface without having a flection. At this time, the projection module 11 projects the keyboard template 20, which is designed according to the use purpose, using a low output red laser light source with high optical efficiency.

[7] Then, the IR module 13 enables a boundary surface made of the IR light to horizontally scan a portion immediately on the surface on which the keyboard template 20 is projected, and filters and senses IR light reflected from the surface through an IF filter. The IR light is invisible to the human eye, but scans 2 to 3mm above the surface in short bursts. [8] The sensor module 15 is equipped with a CMOS camera for photographing and imaging the keyboard template 20.

[9] The controller 17 analyzes a sensing signal and an image input from the sensor module 15, recognizes a key input based on the analysis result, and transfers it to a display device.

[10] In the conventional projection keyboard, when the projection keyboard is placed on the horizontal plane, the keyboard template is formed accurately. However, if the projection keyboard is not placed on the horizontal plane and therefore a slope is generated, the keyboard template projected from theprojection module is distorted. Consequently, there occurs a problem in that the area of the keyboard template is expanded or reduced, and thus key inputs are not recognized. Disclosure of Invention Technical Problem

[11] Accordingly, the present invention has been made in view of the above problems occurring in the prior art, and an object of the present invention is to provide a method of correcting keyboard template coordinates of a projection keyboard, which can recognize key inputs accurately even when the keyboard template area is expanded or reduced by correcting distortion betweena reference keyboard template and a projected keyboard template, which occurs as a result of comparison between them, using a coordinate value of the reference keyboard template on the basis of the projected keyboard template.

Technical Solution

[12] To achieve the above object, according to the present invention, there is provided a method of correcting keyboard template coordinates of a projection keyboard, comprising a projection module that projects a keyboard template, an Infra Red (IR) module that horizontally scan a portion immediately on a surface on whichthe keyboard template is projected, a sensor module that captures an image of the keyboard template, and a controller that generates an input event based on the image input from the sensor module, the methodincluding a scan step of capturing the image of the keyboard template when power is on and generating a captured image frame, a distortion comparison step of determining whether a distortion existsin the captured image frame by comparing the captured image frame and a previously stored reference image frame, a corrected coordinate value generating step of, if, as a result of the determination, the distortion exists in the captured image frame, generating a corrected coordinate value according to thedistortion of the captured image frame, a coordinate value change step of updating a previously stored reference coordinate value table to the corrected coordinate value, and a key recognition step of recognizing a key input event based on the corrected coordinate value.

[13] The distortion comparison step includes treating the captured image frame as errorwhen the captured image frame is deviated from a minimum scan area and a maximum scan area.

[14] The reference image frame includes a keyboard template image captured on a horizontal plane.

[15] Thecorrected coordinate value generating step includes checking a reduction / magnification ratio of the captured image frame on the basis of the reference image frame, expanding the reference coordinate value according to the reduction/magnification ratio, and generating the corrected coordinate value.

[16] The method further includes a reset step of resetting the reference coordinate value table when power is on after power is off.

Advantageous Effects

[17] In accordance with the method of correcting keyboard template coordinates of the projection keyboard constructed above, the coordinate value of a keyboard template is corrected according to the slope of the projection keyboard. Accordingly, there isan advantage in that key inputs can be recognized accurately irrespective of a variation in the size of the keyboard template. Brief Description of the Drawings

[18] Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

[19] FIG. 1 is a conceptual view illustrating the construction of a general projection keyboard;

[20] FIG. 2 is a schematic block diagram of a projection keyboard for implementing a method of correcting keyboard template coordinates of the projection keyboard according to the present invention;

[21] FIG. 3 is a flowchart illustrating the method of correcting keyboard template coordinates of the projection keyboard according to the present invention;

[22] FIGS. 4 to 6 illustrate a variation in the keyboard template according to the slope of the projection keyboard; and

[23] FIGS. 7 and 8 illustrate a reference image frame and a captured image frame.

[24] <Explanation of reference numerals of main elements in the drawings>

[25] 11: projection module 13: IR module

[26] 15: sensor module 20: keyboard template

[27] 110: memory 120: controller

[28] F: reference image frame F': captured image frame Mode for the Invention

[29] The construction of a projection keyboard enabling keyboard template correction according to the present invention will now be described in detail with reference to the accompanying drawings.

[30] In describing the present invention hereinafter, if it is determined that detailed description of the related functions or constructions make the gist of the present invention unnecessarily vague, the detailed description will be omitted. Further, terms to be described later on are terms that have been defined in consideration of the functions in the present invention and may be varied according to a user, an operator's intention, customs, etc. Thus, the definitions should be given on the basis of overall contents of the specification.

[31] FIG. 2 is a schematic block diagram of a projection keyboard for implementing a method of correcting keyboard template coordinates of the projection keyboard according to the present invention.

[32] Referring to FIG. 2, a projection keyboard 100 for implementing a methodof correcting keyboard template coordinates of a projection keyboard according to the present invention includes a projection module 11, an IR module 13, a sensor module 15, memory 110 and a controller 120.

[33] The projection module 11, the IR module 13 and the sensor module 15 are operated in the same manner as those of the conventional projection keyboard described with reference to FIG. 1, and are therefore assigned the same reference numerals and redundant description thereof is omitted. In addition, constituent elementssuch as an on/off switch, a speaker, a radio communication module and a battery are known in the art and are described for simplicity.

[34] The memory 110 stores various data necessary for system driving, a reference image frame and a reference coordinate value table.

[35] The controller 120 controls an overall operation of the system. The controller 120 determines distortion of a keyboard template 20 by employing an image frame of the keyboard template 20, which is captured by the sensor module 15 when power is on, and expands a coordinate value according to distortion when the distortion is generated so that the IR module 13 and the sensor module 15 can recognize key inputs. Meanwhile, the controller 120 resets a reference coordinate value table when power is on after power was off. In other words, the controller 120 restores a coordinate value table, which is updated to a corrected coordinate value, to an original reference coordinate value.

[36] Hereinafter, the method of correcting keyboard template coordinates of the projection keyboard according to the present invention is described in detail with reference to the accompanying drawings.

[37] FIG. 3 is a flowchart illustrating the method of correcting keyboard template coordinates of the projection keyboard according to the present invention. FIGS. 4 to 6 illustrate a variation in the keyboard template according to the slope of the projection keyboard. FIGS. 7 and 8 illustrate a reference image frame and a captured image frame.

[38] The size of the keyboard template when the projection keyboard is in an upright position to the horizontal plane accurately, as shown in FIG. 4, differs from the size of the keyboard template when the projection keyboard is inclined, as shown in FIGS. 5 and 6. In other words, whenthe projection keyboard has an acute angle, the size of the keyboard template is small, and when the projection keyboard has an obtuse angle, the size of the keyboard template is large.

[39] Due to this, in the prior art, when the projection keyboard is inclined and, therefore, the size of the keyboard template is changed, key inputs are not recognized.

[40] In order to solve this problem, in the present invention, a coordinate value of the keyboard template is corrected by changing the coordinate value according toa slope so that key inputs are recognized.

[41] To be more specific, when power is turned on (SlOl), the controller 120 controls the CMOS camera of the sensor module 15 to capture an image of the keyboard template 20 projected from the projection module 11, creates a captured image frame F' as shown in FIG. 8, and stores the generated image frame F' in the memory 110 (S 102). At this time, the controller 120 may preferably create the captured image frame F' only when any object does not exist through the input of the IR module 13 in order to obviate error of the captured image frame F'.

[42] The controller 120 determines whether a distortion exists in the captured image frame F' by comparing the captured image frame F' stored in the memory 110 and a reference image frame F, which is previously stored as shown I FIG. 7, (Sl 10). At this time, the reference image frame F is defined as a keyboard template image captured on the horizontal plane. Further, when the captured image frame F' is deviated from a minimum scan area and a maximum scan area (that is, key inputs are impossible since the slope is sharp and therefore the keyboard template is very small, and a recognition area is exceed since the slope is too great), the controller 120 treats it as error.

[43] If, as a result of the determination, the distortion exists in the captured image frameF' (S 121), the controller 120 checks a reduction/magnification ratio of the captured image frame F' on the basis of the reference image frame F (S 122) and generates a corrected coordinate value by expanding the reference coordinate value according to the checked reduction/magnification ratio (S 123). That is, in the case where the captured image frame F' is expanded 1.5 times from the reference image frame F, the controller 120 expands the corrected coordinate value by 1.5 times from the reference coordinate value. However, if, as a result of the determination, the reduction/magnification ratio of the reference image frame F is identical to that of the captured image frame F' (that is, distortion does not exist in the captured image frame F'), the controller 120 recognizes a key input according to the reference coordinate value and generates a key event (S 124).

[44] The controller 120 then updates the previously stored reference coordinate value table using each generated corrected coordinate value (S 130). That is, the controller 120 changes a reference coordinate value of each key area to a corrected coordinate value, such as by changing the reference coordinate value of a key area "A" to a corrected coordinate value of "1-1" when the reference coordinate value is " 1".

[45] In this state, if a user performs a key input, the controller 120 recognizes the key input through a signal and an image, whichare input from the IR module 13 and the sensor module 15, according to the corrected coordinate value, and generates a key event (S 140).

[46] Meanwhile, when power is on after power was off, the controller 120 resets the reference coordinate value table. That is, the controller 120 restores the coordi- natevalue table updated to the corrected coordinate value to an original reference coordinate value.

[47] Although distortion of the keyboard template exists as a result of sensing the slope of the projection keyboard when power is on, an accurate key input is made possible by taking the distortion into consideration. Accordingly, the keyboard template of the present invention can be used without restriction to the place.

[48] Although the specific embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Industrial Applicability

[49] The projection keyboard according to the present invention can be used as an input unit of a portable electronic device.

Claims

[1] A method of correcting keyboard template coordinates of a projection keyboard, comprising a projection module that projects a keyboard template, an Infra Red (IR) module that horizontally scan a portion immediately on a surface on which the keyboard template is projected, a sensor module that captures an image of the keyboard template, and a controller that generates an input event based on the image input from the sensor module, the method comprising: a scan step of capturing the image of the keyboard template when power is on and generating a captured image frame; a distortion comparison step of determining whether a distortion existsin the captured image frame by comparing the captured image frame and a previously stored reference image frame; a corrected coordinate value generating step of, if, as a result of the determination, the distortion exists in the captured image frame, generating a corrected coordinate value according to the distortion of the captured image frame; a coordinate value change step of updating a previously stored reference coordinate value table to the corrected coordinate value; and a key recognition step of recognizing a key input event based on the corrected coordinate value.

[2] The method of claim 1, wherein the distortion comparison step comprises treating the captured image frame as errorwhen the captured image frame is deviated from a minimum scan area and a maximum scan area.

[3] The method of claim 1, wherein the reference image frame comprises a keyboard template image captured on a horizontal plane.

[4] The method of claim 1, wherein the corrected coordinate value generating step compriseschecking a reduction /magnification ratio of the captured image frame on the basis of the reference image frame, expanding the reference coordinate value according to the reduction/magnification ratio, and generating the corrected coordinate value.

[5] The method of claim 1, further comprising a reset step of resetting the reference coordinate value table when power is on after power is off.