# US 12,000,687 B2 · Digital track recording device and coordinate calibration method

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- Number: US 12,000,687 B2
- Document ID: US12000687B2
- Status: Granted
- Kind: B2
- Application number: 17/610,953
- Filed: 2020-12-09
- Published: 2023-01-05
- Granted: 2024-06-04
- Earliest claimed: 2020-03-24
- Applicants: Qingdao Luobo Smart Education Technologies Co., Ltd; Qingdao Luobo Digital Technologies Co., Ltd
- Inventors: Shujun Yin
- Web page: https://patentgrep.com/patent/US12000687B2

## CPC

- G01B 11/002: {for measuring two or more coordinates}
- G06F 3/0321: {by optically sensing the absolute position with respect to a regularly patterned surface forming a passive digitiser, e.g. pen optically detecting position indicative tags printed on a paper sheet (constructional details of pen-shaped pointing devices G06F3/03545, G06F3/03542, G06F3/037)}
- G06F 3/03545: {Pens or stylus}
- G06F 3/038: Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
- G06F 3/0418: {for error correction or compensation, e.g. based on parallax, calibration or alignment}
- G06F 3/046: by electromagnetic means
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A coordinate calibrating method includes the steps of: (1) reading paper coordinates by adopting two OID sensors, comparing the coordinates read by the two OID sensors with pre-designed coordinates of paper to obtain coordinate deviation of positions of the two OID sensors, and according to the coordinate deviation, calculating an inclination angle value θ generated by the coordinates of the two OID sensors; and (2) according to the coordinate deviation and the inclination angle value, calibrating an actually read coordinate position of a pen by selecting the second OID sensor as a reference point, translating horizontally and vertically coordinates of the pen to be corrected first, and then rotating the coordinates by the angle θ with reference to the second OID sensor, so that the positions of the two OID sensors coincide with pre-designed standard positions, and the coordinate position of the pen is calibrated.

## Claims

### Claim 1

A coordinate calibrating method, comprising the following steps of: (1) reading paper coordinates with two Optical Identification (OID) sensors, comparing the coordinates read by the two OID sensors with pre-designed coordinates of paper to obtain coordinate deviation of positions of the two OID sensors, and according to the coordinate deviation, calculating an inclination angle value θ generated by the coordinates of the two OID sensors; and (2) according to the coordinate deviation and the inclination angle value, calibrating an actually read coordinate position of a pen by selecting the second OID sensor as a reference point, translating horizontally and vertically coordinates of the pen to be corrected first, and then rotating the coordinates by the angle θ with reference to the second OID sensor, so that the positions of the two OID sensors coincide with pre-designed standard positions, and the coordinate position of the pen is calibrated.

### Claim 2 (depends on 1)

The coordinate calibrating method according to claim 1, wherein sequences of the translating and the rotating during calibrating are capable of being exchanged, which means that the coordinates are rotated by the angle θ with reference to the second OID sensor first, and then points of the coordinates to be corrected are translated horizontally and vertically.

### Claim 3 (depends on 1)

A digital track recording device with the method according to any one of claim 1, comprising the two OID sensors, a device body and a page number recognition area, wherein the two OID sensors are arranged at an edge area of the device body and used for reading coordinates of paper, and the page number recognition area is arranged at a top end of the device body and used for recognizing a page number of the paper.

### Claim 4 (depends on 3)

The digital track recording device according to claim 3, wherein a face shell of the device body is provided with a groove structure with the same size as the paper.

### Claim 5 (depends on 3)

The digital track recording device according to claim 3, wherein the digital track recording device is a handwriting board adopting an electromagnetic induction technology.