# US 9,519,380 B2 · Handwriting systems and operation methods thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,519,380 B2 - Document ID: US9519380B2 - Status: Granted - Kind: B2 - Application number: 14/876,820 - Filed: 2015-10-07 - Published: 2016-01-28 - Granted: 2016-12-13 - Earliest claimed: 2011-12-22 - Assignees: Pixart Imaging Inc. - Applicants: PixArt Imaging Inc. - Inventors: Han-Ping Cheng; Shu-Sian Yang - Web page: https://patentgrep.com/patent/US9519380B2 ## CPC - G06F 3/0425: {using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected (tracking a projected light spot to determine a position on a display surface G06F3/0386)} - G06F 3/045: using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact - G06F 3/04883: for inputting data by handwriting, e.g. gesture or text - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A handwriting system includes a light source module, an image sensing apparatus and a processing circuit. The light source module is configured to provide a light source to illuminate an object on a plane. The image sensing apparatus is disposed on the plane and configured to capture an image of the object reflecting light emitted by the light source. The processing circuit is electrically connected to the image sensing apparatus and configured to receive the image captured by the image sensing apparatus, analyze the shape of each of light spot(s) in the captured image and screen out the light spot(s) not conforming to the shape of the object. Another handwriting system and two handwriting system operation methods are also provided. ## Claims ### Claim 1 A handwriting system, comprising: a light source module configured to provide a light source to illuminate an object on a plane; an image sensing apparatus disposed on the plane and configured to capture an image of the object reflecting lights emitted by the light source; and a processing circuit electrically connected to the image sensing apparatus and configured to receive the image captured by the image sensing apparatus, analyze a shape of at least one light spot in the captured image, and screen out at least one light spot not conforming to the shape of the object according to an aspect ratio of the at least one light spot in the captured image, wherein when a merged light spot having a width shorter than a threshold at a position is located, the processing circuit is configured to divide the merged light spot into two individual light spots at the position, and determine whether each of the two individual light spots has image characteristics conforming to the shape of the object. ### Claim 2 (depends on 1) The handwriting system according to claim 1, wherein the processing circuit is further configured to convert the captured image into a binary image and determine if the binary image has at least one light spot conforming to the shape of the object by using the Hough Transform. ### Claim 3 (depends on 1) The handwriting system according to claim 1, wherein the light source module comprises: a laser source configured to generate a spot light source; and an optical element configured to convert the spot light source into a linear light source serving as the light source. ### Claim 4 (depends on 3) The handwriting system according to claim 3, wherein the optical element comprises a cylindrical lens or a microelectromechanical system (MEMS) scanning mirror, the cylindrical lens is configured to convert the spot light source into the linear light source serving as the light source, the MEMS scanning mirror is configured to modulate the emission direction of the spot light source and thereby forming the light source. ### Claim 5 (depends on 1) The handwriting system according to claim 1, wherein the light source module comprises: a plurality of laser light sources arranged in parallel to each other and configured to emit light and thereby forming the light source. ### Claim 6 (depends on 1) The handwriting system according to claim 1, wherein the plane is a parallelogram. ### Claim 7 (depends on 1) The handwriting system according to claim 1, wherein the plane comprises a virtual panel. ### Claim 8 An operation method of a handwriting system, the handwriting system comprising a light source module and an image sensing apparatus, the light source module being configured to provide a light source to illuminate an object on a plane, the image sensing apparatus being disposed on the plane and configured to capture an image of the object reflecting lights emitted by the light source, the operation method comprising: obtaining the image captured by image sensing apparatus; analyzing a shape of at least one light spot in the captured image; dividing a merged light spot into two individual light spots at a position when the merged light spot having a width shorter than a threshold at the position is located; determining whether each of the two individual light spots has image characteristics conforming to a shape of the object; and screening out at least one light spot not conforming to the shape of the object according to an aspect ratio of the at least one light spot in the captured image. ### Claim 9 (depends on 8) The operation method according to claim 8, further comprising: converting the captured image into a binary image and determining if the binary image has at least one light spot conforming to the shape of the object by using the Hough Transform. ### Claim 10 A handwriting system, comprising: a light source module configured to provide a light source to illuminate an object on a plane; an image sensing apparatus disposed on the plane and configured to capture an image of the object reflecting lights emitted by the light source; and a processing circuit electrically connected to the image sensing apparatus and configured to receive the image captured by the image sensing apparatus, analyze a shape of at least one light spot in the captured image, and screen out at least one light spot not conforming to the shape of the object according to a size of the at least one light spot in the captured image on y-axis or on x-axis, wherein when a merged light spot having a width shorter than a threshold at a position is located, the processing circuit is configured to divide the merged light spot into two individual light spots at the position, and determine whether each of the two individual light spots has image characteristics conforming to the shape of the object. ### Claim 11 An operation method of a handwriting system, the handwriting system comprising a light source module and an image sensing apparatus, the light source module being configured to provide a light source to illuminate an object on a plane, the image sensing apparatus being disposed on the plane and configured to capture an image of the object reflecting lights emitted by the light source, the operation method comprising: obtaining the image captured by image sensing apparatus; analyzing a shape of at least one light spot in the captured image; dividing a merged light spot into two individual light spots at a position when the merged light spot having a width shorter than a threshold at the position is located; determining whether each of the two individual light spots has image characteristics conforming to a shape of the object; and screening out at least one light spot not conforming to the shape of the object according to a size of the at least one light spot in the captured image on y-axis or on x-axis.