Presentation board digitizers

Details Presentation board digitizers Presentation board digitizers

2001-12-18

2004-04-20

Shankar, Vijay (Department: 2673)

Computer graphics processing and selective visual display system

Display peripheral interface input device

Touch panel

C345S176000, C178S018010, C178S018040, C178S019010, C178S019020

Reexamination Certificate

active

06724371

ABSTRACT:

FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to digitizers. More particularly, the present invention relates to devices for use with presentation boards and pens for digitizing lines drawn manually thereon.
Throughout the last decade the presentation of data in a group setting has become highly digitized, involving the use of technologically advanced audio-visual devices. As such, the use of a conventional drawing board, such as a whiteboard, in such presentations has rapidly declined.
Still, some presenters often prefer to use a marker and whiteboard to present and develop ideas during group sessions. To enable recording of information presented by such means, several digitized whiteboard systems have been developed.
Such systems typically employ a combination of transmitters and receivers for processing signals from a handheld device. The writing movements produced by these devices are traced and recorded, and as a result the textual and graphical content of a session can be digitized and ported to a computer.
Various techniques are used for determining the position of a handheld device or stylus on a flat surface. U.S. Pat. No. 4,564,928 to Glenn et al., U.S. Pat. No. 4,886,943 to Suzuki et al., U.S. Pat. Nos. 4,910,363 and 5,073,685 to Kobayashi et al. and U.S. Pat. No. 5,097,102 to Yoshimura et al. all disclose systems in which a vibrating element associated with a pen transmits vibrations through the material of a board. The vibrations are detected by transducers attached to the board and the position of the pen is calculated from the transmission time of the vibrations through the board. These systems inherently function exclusively when the pen is in contact with the board such that vibrations are transferred to the board. As a result, no special mechanism is required to distinguish writing from non-writing pen movements.
These systems are generally inaccurate due to non-uniform transmission times through the board. In fact, they typically require highly specialized board structures which renders them expensive and inconvenient.
An alternative approach is the use of air-borne ultrasound signals. Examples of such systems are described in U.S. Pat. No. 4,777,329 to Mallicoat, U.S. Pat. No. 4,814,552 to Stefik et al., U.S. Pat. No. 4,506,354 to Hansen U.S. Pat. No. 4,758,691 and to De Bruyne and PCT/IL98/00093, filed Feb. 25, 1998 by Pegasus Technologies Ltd., which is incorporated by reference as if fully set forth herein.
These systems employ various combinations of ultrasound transmitters and receivers arranged at two points fixed relative to a board and on a movable writing implement. The position of the movable implement is then derived by triangulation. These systems typically require an additional hard-wired or electromagnetic link, such as an infrared link, between the movable implement and a base unit to provide timing information for time-of-flight ultrasound calculations. An additional switch is also required to identify when the movable element is in contact with the board.
These systems are typically limited to relatively small boards. This is because of signal-to-noise ratio (SNR) limitations which interfere with obtaining accurate measurements. The volume of ultrasound used cannot be very high without causing bothersome accompanying whistling noises. Additionally, in a wireless system, power considerations severely limit the transmitted volume. In order to generate reliable position information, the transmitter-to-receiver distance must therefore be kept small. Attempts to use different sets of receivers for different regions of a large board generally result in discontinuities when the movable element travels from one region to another.
Another shortcoming of these systems is their inability to reproduce rapid interrupted pen strokes such as performed when drawing a dashed line. Typically, the transmitter or receiver element in the pen turns off when the pen is inactive and is re-activated each time the pen comes in contact with the board. The system then takes a fraction of a second to resynchronize before it responds correctly. In the case of short strokes, the length of the operative stroke may be comparable with the response time of the system, thereby giving very poor results.
An additional problem of some of the airborne ultrasound digitizer systems is that the ultrasound transmitter or receiver element is mounted asymmetrically to the side of the drawing implement or stylus. As a result, the measured position is offset from the true drawing position in a direction which changes with rotation of the drawing implement. This may result in discontinuities and illegible writing in the digitized image when the drawing implement position is changed between strokes.
Furthermore, conventional presentation board digitizer systems are typically limited to use with specially produced writing implements. This renders them expensive since pens have a very limited lifetime. Even where the ink cartridge is separately replaceable, the components used must be of a very specific design to be compatible.
Finally, styluses which employ a color writing tip are usually restricted to using a single color tip and cannot employ different colors or a tip of a different function, since the recordation system cannot distinguish between the different tips.
There is therefore a need for a reliable, low-cost, digitizer system which may be used with conventional presentation boards of all sizes for determining accurately the position of a drawing implement on the board. Additional needs and improvements provided by the present invention are described in the specification that follows.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a handheld device for use with a board supplemented with a processing system for digitizing operative strokes of the handheld device on the board, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving a portion of a body of a drawing implement with its drawing tip extending from the central orifice, the housing being formed with a plurality of openings being circumferencly arranged at the distal end of the housing and communicating with the bore; and (b) an ultrasonic receiver or transmitter device mounted within the housing, remote from the drawing tip, yet in close proximity with the bore, the device being for receiving or transmitting an intermittent ultrasound signal through the bore and the plurality of openings, thereby enabling triangulation of the drawing tip.
According to another aspect of the present invention there is provided a handheld device for use with a board supplemented with a processing system for digitizing operative strokes of the handheld device on the board, the handheld device comprising (a) a housing having a substantially cylindrical bore therein terminating at a distal end of the housing with a central orifice communicating with the bore, the housing receiving and releasing a portion of a body of a removably attachable drawing implement through the orifice with its drawing tip extending from the central orifice; (b) a retainer in the housing for releasably retaining the removably attached drawing implement within the housing; (c) an ultrasonic receiver or transmitter device being internally or externally connected to the housing for receiving or transmitting an intermittent ultrasound signal; (d) a microswitch in the housing being actuated when contacted by a proximal end of the body, so as to be responsive to a force exerted on the drawing tip of the drawing implement; and (e) an electronic circuitry being in the housing and electronically communicating with the microswitch for affecting operation of the device at least when the microswitch indicates that the force is exerted on the drawing tip of the drawing implement.
According to yet another aspect of the present invention there is provided a handheld d

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