Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
2000-12-04
2002-08-06
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S173000, C178S018010
Reexamination Certificate
active
06429857
ABSTRACT:
This invention generally relates to infrared (“IR”) enabled touch systems or touch screens. More particularly, the present invention is directed to an inventive system and method to improve the resolution of IR touch systems. The system and method provide a higher resolution for determining the location of a touch on the screen through the use of on-axis and off-axis IR transmitter-receiver detection. In one embodiment of the inventive method, the touch location is determined by a multiple-step process of first identifying a coarse touch location and then determining a finer location for the touch within the coarse location area. The increased resolution of touch location is achievable with the inventive system and method without the need for an increased density of IR transmitters and receivers or the need for increased processor speed.
BACKGROUND DESCRIPTION
Touch systems are becoming more prevalent in everyday activities. In addition to touch systems being used in money access centers, lobby directories, museum and entertainment kiosks, and automobile positioning system displays, miniaturized touch systems have become the technology medium of choice for pocket diaries and organizers. While IR touch systems may be used in these applications, in order to be successful in these and other emerging markets, the determination of touch location in touch systems, including IR touch systems, must be made quickly, accurately and precisely. This is especially the case for pocket diaries which may use a relatively small point stylus or pointer as the user's means of identifying a desired operation or system selection.
Generally, the location of a touch is identified through use of IR transmitters, typically light emitting diodes (“LEDs”), and IR receivers, typically phototransistors (“photos”). An example illustration of a prior art touch screen is shown in
FIG. 1. A
set of n IR transmitters
20
(
1
) to
20
(n) and another set of m IR transmitters
40
(
1
) to
40
(m), for example LEDs, are positioned along two adjacent edges of a touch screen
11
. A set of n IR receivers
30
(
1
) to
30
(n) and another set of m IR receivers
50
(
1
) to
50
(m), are positioned along the opposite edges of the touch screen
11
such that each receiver
30
(i) and
50
(i) is aligned on-axis with an opposing transmitter, respectively
20
(i) and
40
(i). As defined, transmitters
20
(i) and
40
(i) and receivers
30
(i) and
50
(i) mean each sequential transmitter and receiver where i=1, 2, 3, i, i+1, . . . , n−1, n, for the n transmitters and respective receivers, and where i=1, 2, 3, i, i+1, . . . , m−1, m, for the m transmitters and respective receivers.
In the conventional prior art touch system, the number of transmitters used along the screen perimeter equals the number of receivers positioned along the opposing screen edge, because the transmitters are each aligned on-axis with a receiver. As shown in
FIG. 1
, the typical touch screen
11
creates a Cartesian coordinate grid of x-coordinate transmitter-receiver pairs, for example x-coordinate pair
20
(
1
) and
30
(
1
), and y-coordinate transmitter-receiver pairs, for example y-coordinate pair
40
(
3
) and
50
(
3
). The detection pattern is accordingly an orthogonal grid of x and y coordinates.
The location of a touch is determined by scanning the x-coordinate pairs and y-coordinate pairs and identifying which transmitter-receiver pairs show a blockage of IR light. The scanning process entails activation of each receiver
30
(i) and
50
(i) and activating, or flashing, the opposing transmitter respectively
20
(i) and
40
(i), detecting whether the transmitter
20
(i) and
40
(i) IR signal is received by the respective on-axis receiver
30
(i) or
50
(i), and then deactivating each receiver
30
(i) and
50
(i). This receiver activation, on-axis transmitter flash, receiver deactivation process is repeated for each on-axis transmitter-receiver pair until all transmitter-receiver pairs are scanned.
The accuracy and precision of the location of a touch for a conventional touch system is dependent upon the density or number of transmitters and receivers positioned along the perimeter of the screen
11
. One problem with such an orthogonal detection pattern, as illustrated in
FIG. 1
, is that if a touch diameter 95 is less than the spacing of adjacent transmitters and adjacent receivers, a touch may go undetected as being in an area where no beam crosses.
Moreover, the time period required to make the touch location determination is dependent upon the speed of the processor used to activate and flash the transmitters and receivers, and to detect whether the emitted IR signal is received by the receiver. Obviously, unless the processing capability of the system is increased, as more transmitter-receiver pairs are included in the touch system, the time to identify a touch location will increase along with the time period to scan the complete set of transmitter-receiver pairs.
Because the IR transmitters and receivers, or system optoelectronics, comprise a significant portion of the overall cost of an IR touch system, an increase in the number of optoelectronic devices would result in a dramatic increase in the overall system cost. Similarly, because the processor electronics are another significant portion of the cost of an IR touch system, an increase in processing speed to maintain a maximum time period for touch identification, would likewise cause a substantial increase in the system cost.
In addition to the noted on-axis conventional touch systems, one device described in Japanese Patent Application No. TOKKAI HEI 11-232024 for an Optical Position Detection Device, owned by Alpine Electronics, Inc., provides for the detection of two or more adjacent phototransistors within the range of light emitted from an opposing light emitting diode. The object of the Alpine system is to eliminate the restrictions of the prior art with respect to the number, position and placement of LEDs and phototransistors that would allow for possible improvements in position detection accuracy. While apparently describing detection of LED output through the use of off-axis phototransistors, the Alpine system does not appear to describe or disclose any method for efficiently scanning the LED-phototransistor pairs. Indeed, the device operation description appears to call for the sequential cycling all LEDs and detecting multiple phototransistors for each of the LEDs activated. Such a device would require significantly increased computer processing capability to handle the increased information provided from detecting multiple phototransistors for every LED, and cycling through each LED along the perimeter of the touch screen.
Accordingly, there is a need for a IR touch system that has an improved resolution capability for accurately and precisely identifying the location of a touch, but that does not require significantly more IR transmitters and receivers, and does not require significantly increased computer processing requirements to control the transmitter and receivers and process the data resulting from the scanning operation. Such a system or method does not currently exist, but would greatly extend the utility and capability of IR touch screen systems.
SUMMARY OF THE INVENTION
In view of the shortcomings of the prior art, it is an object of the present invention to provide an improved resolution infrared touch system and method that provides an accurate and precise determination of the location of a touch without increasing the number of touch screen IR transmitters or IR receivers. It is a further object of the present invention that the improved touch position resolution does not necessitate extended or higher speed processing requirements to maintain system resolution and speed of operation.
To achieve this and other objects, and in view of its purposes, the present invention provides an infrared touch system having increased resolution for determining position of a touch on a touch screen, the infrared touch syste
Deacon John
Grice, Jr. Henry A.
Knetsch Robert W.
Masters Timothy E.
Elo Touchsystems, Inc.
Maier Christopher J.
Saras Steven
LandOfFree
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