EP0270909A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Contact sensor for computer input stylus device
Assignee: International Business Machines Corp
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Filing: 1987-11-24
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Granted: —
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Expires: 2007-11-24
Abstract
Abstract An acoustic contact sensor for handwritten computer input is disclosed. The contact sensor comprises ultrasonic sending transducer means (7) coupled to a writing surface (5) or display screen, receiving transducer means (9, 11) provided with the stylus (3), and circuit means (13) for providing a logic signal to a computer (17) when contact is made, in particular when the acoustic signal transferred along the writing surface and received in the stylus exceeds a given threshold. In an alternative embodiment, an ultrasonic sender is provided in the stylus, with the acoustic receiver being connected to the writing surface or display screen.
Inventors
- 👤 Richard Lawrence Garwin
- 👤 James Lewis Levine
- 👤 Michael Alan Schappert
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 19:38
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/033; G06F3/0354; G06F3/03545; Y; Y10; Y10S; Y10S367/00; Y10S367/907
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
94 words
Apparatus for sensing contact between a pen type stylus device for computer data input and a writing surface, characterized by: a) ultrasonic sending transducer means (7) coupled to the writing surface (5) for projecting acoustic waves to said writing surface; b) receiving transducer means (9) coupled to said stylus (3) for reception of said acoustic waves from said sending transducer means, and conversion of said acoustic waves to an electrical signal; and c) circuit means (13) for providing a logic signal to the computer (17) whenever the acoustic signal exceeds a predetermined threshold value.
Claim 2
Dependent Claim
94 words
Apparatus for sensing contact between a pen type stylus device for computer data input and a writing surface, characterized by: a) ultrasonic sending transducer means (7) coupled to the writing surface (5) for projecting acoustic waves to said writing surface; b) receiving transducer means (9) coupled to said stylus (3) for reception of said acoustic waves from said sending transducer means, and conversion of said acoustic waves to an electrical signal; and c) circuit means (13) for providing a logic signal to the computer (17) whenever the acoustic signal exceeds a predetermined threshold value.
Claim 3
Dependent Claim
88 words
Apparatus for sensing contact between a pen type stylus device for computer data input and a writing surface, characterized by: a) ultrasonic sending transducer means coupled to said stylus for projecting acoustic waves to the writing surface; b) receiving transducer means coupled to the writing surface for reception of said acoustic waves from said sending transducer means, and conversion of said acoustic waves to an electrical signal; and c) circuit means for providing a logic signal to the computer whenever the acoustic signal exceeds a predetermined threshold value.
Claim 4
Dependent Claim
88 words
Apparatus for sensing contact between a pen type stylus device for computer data input and a writing surface, characterized by: a) ultrasonic sending transducer means coupled to said stylus for projecting acoustic waves to the writing surface; b) receiving transducer means coupled to the writing surface for reception of said acoustic waves from said sending transducer means, and conversion of said acoustic waves to an electrical signal; and c) circuit means for providing a logic signal to the computer whenever the acoustic signal exceeds a predetermined threshold value.
Claim 5
Dependent Claim
23 words
An apparatus according to claim 1 or 2 wherein said stylus is linked to the computer device by a battery operated wireless transmitter.
Claim 6
Dependent Claim
34 words
An apparatus according to claim 1 or 2 wherein said ultrasonic sending transducer means transmits short pulses approximately 50 microseconds in length of duration with delays of approximately 500 microseconds in length between pulses.
Claim 7
Dependent Claim
25 words
An apparatus according to claim 1 or 2 wherein said writing surface has acoustic absorbers or scatterers located at the edges of said writing surface.
Claim 8
Dependent Claim
22 words
An apparatus according to claim 1 or 2 wherein said ultrasonic sending transducer means repetitively sweeps the frequency of said acoustic waves.
Claim 9
Dependent Claim
76 words
An apparatus according to claim 6 wherein said ultrasonic sending transducer means (7) comprises: a) digital oscillator means (32) for operation at some multiple times the desired ultrasonic frequency; b) divider means (34) for reducing the output of said digital oscillator means by the said multiplication factor; c) amplifier means (36) for driving said transducer; and d) low-frequency sweep generator means (30) for modulating the frequency of said digital oscillator means to provide a frequency sweep.
Claim 10
Dependent Claim
74 words
An apparatus according to claim 1 or 2 wherein said receiving transducer means (9) comprises: a) pre-amplifier means (40) for amplifying the signal picked up by a receiving transducer; b) switched capacitor tracking filter means (42) for tracking the transmitted frequency; c) rectifier means (44) for rectifying the output of said tracking filter means; d) low-pass filter means (46); and e) comparator means (48) for comparing said received signal with a predetermined threshold signal.
Claim 11
Dependent Claim
64 words
An apparatus according to claim 8 wherein said receiving transducer means (9) further comprises: a) second rectifier means (52) connected to the output of said pre-amplifier means (40); b) second low-pass filter means (54) for filtering the output of said second rectifier means; and c) second comparator means (56) for comparing the output of said second low-pass filter means to a predetermined threshold signal.
Claim 12
Dependent Claim
36 words
An apparatus according to claim 8 or 9 wherein the output of each of said respective comparator means (48, 56) is connected to an OR gate (58) to form a composite contact signal for the computer.
Claim 13
Dependent Claim
57 words
Apparatus for sensing contact between a pen type stylus device for computer data input and a writing surface, characterized by: battery powered electrical oscillation circuit means for resonance of stylus transducer means such that upon contact of said stylus (3) to said writing surface (5) there is a change in the amplitude or frequency of the oscillation.
Claim 14
Dependent Claim
57 words
Apparatus for sensing contact between a pen type stylus device for computer data input and a writing surface, characterized by: battery powered electrical oscillation circuit means for resonance of stylus transducer means such that upon contact of said stylus (3) to said writing surface (5) there is a change in the amplitude or frequency of the oscillation.
Claim 15
Dependent Claim
40 words
An apparatus according to claim 11 wherein a signal indicating a contact signal between said stylus and said writing surface is sent to the computer by a wireless link between said stylus and the computer in the infra-red frequency range.
References Cited (Backward Citations)
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