Patent number 8610009 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a capacitive touch sensor for detecting proximity and location of a body, more especially to a one- or two-dimensional capacitive sensor.
"There are various forms of touch sensitive controls which use a capacitive sensor to sense the presence of a body such as a user's finger. A form of touch sensitive control is disclosed in WO-00/44018. In this example a pair of electrodes are provided which act as a key so that the presence of a body such as a user's finger is detected as a result of a change in an amount of charge which is transferred between the two electrodes. With this arrangement, one of the electrodes (labeled X) is driven with a drive circuit and the other of the pair of electrodes (labeled Y) is connected to a charge measurement circuit which detects an amount of charge present on the Y plate when driven by the X plate. As disclosed in WO-00/44018 several pairs of electrodes can be arranged to form a matrix of sensing areas which can provide an efficient implementation of a touch sensitive two-dimensional position sensor. Such two dimensional capacitive transducing (2DCT) sensors are typically used with devices which include touch sensitive screens or touch sensitive keyboards/keypads which are used in, for example, consumer electronic devices and domestic appliances.
"Devices employing 2DCT sensors have become increasingly popular and common not only in conjunction with personal computers but also in all manner of other appliances such as personal digital assistants (PDAs), point of sale (POS) terminals, electronic information and ticketing kiosks, kitchen appliances and the like. 2DCT sensors are frequently preferred to mechanical switches for a number of reasons. For example, 2DCT sensors require no moving parts and so are less prone to wear than their mechanical counterparts. 2DCT sensors can also be made in relatively small sizes so that correspondingly small, and tightly packed keypad arrays can be provided. Furthermore, 2DCT sensors can be provided beneath an environmentally sealed outer surface/cover panel. This makes their use in wet environments or where there is a danger of dirt or fluids entering a device being controlled attractive. In addition, manufactures often prefer to employ interfaces based on 2DCT sensors in their products because such interfaces are often considered by consumers to be more aesthetically pleasing than conventional mechanical input mechanisms (e.g. push-buttons).
"Other devices which may incorporate 2DCT sensors include pen-input tablets and encoders used in machinery for feedback control purposes, for example 2DCT sensors are capable of reporting at least a 2-dimensional coordinate, Cartesian or otherwise, related to the location of an object or human body part by means of a capacitance sensing mechanism.
"As the size of touch sensor arrays increases, it takes longer and longer to acquire a signal value from each of the sensing nodes in the sensor array, which is not desirable. Moreover, it is usually a requirement that the signal acquisition and low level signal processing is carried out with a microcontroller, and it is not desirable to increase the specification of the microcontroller to reduce the data acquisition time."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "A capacitive sensor device may include a capacitive sensor array having a plurality of sensing nodes and a controller operable to acquire touch data from each of the sensing nodes. The capacitive sensor device may be operable to detect the presence and location of a touch from the touch data. The controller may be operable to acquire sets of touch data in a succession of sampling periods such that touch data sets are acquired that include signals from each of the sensing nodes when presence of a touch is absent in a preceding sampling period. The touch data sets may be acquired and may be limited to a subset of the sensing nodes when presence of a touch is detected in a preceding sampling period, each subset being located at and adjacent to the touch location determined in the preceding sampling period.
"In a further embodiment, a corresponding method of operating a capacitive sensor array having a plurality of sensing nodes may detect presence and location of a touch in a succession of sampling periods. A touch data set is acquired with signals from each of the sensing nodes. Touch presence and location is determined on the array from the touch data set. In subsequent sampling periods while presence of a touch continues to be detected, touch data sets may be acquired from respective subsets of the sensing nodes, each subset being located at and adjacent to the touch location determined in the preceding sampling period. Once a touch is no longer detected, the process flow may return to acquiring signals from all of the sensing nodes until such time as presence of another touch is determined.
"In yet a further embodiment, acquisition of frames of touch data may be sped up by limiting the number of sensing nodes sampled to those situated around a touch registered in the previous sample. Time saving may be based on the assumption that the change in touch state from sample to sample is very often that the same touch has persisted and remains at the same location or an adjacent location. The time gained in data acquisition by making this assumption outweighs the time lost in data acquisition as a result of failing to follow touches that persist but move outside the limited sampling area from one sample to the next as a result of rapid motion. In some embodiments, the time gained may become proportionally greater the larger the sensor array, so if the trend to larger sensor arrays continues various embodiments may become more and more useful. This is because the fraction obtained by dividing the total number of sensing nodes of the device by the number of sensing nodes in the defined subset will tend to get larger as the number of sensing nodes in the device increases.
"The capacitive sensor array may be a two-dimensional array of sensing nodes comprising a plurality of first lines and a plurality of second lines, and wherein the subsets of the sensing nodes involve a subset of the first lines. The subsets of the sensing nodes may additionally involve a subset of the second lines. If the subsets are restricted in respect of both the first and second lines, then the sensing nodes sampled are limited to an area in the vicinity of the previously determined touch location. On the other hand, if the subsets are restricted in only in respect of the first lines, then all the sensing nodes along the second lines are sampled, but only a limited number of the sensing nodes along the first lines.
"The first and second lines may be the drive and sense lines of an active or transverse type capacitive sensor, referred to as the X and Y lines in the following, or may be lines relating to a passive or single ended type capacitive sensor. Some embodiments may therefore be applied to active or transverse type capacitive touch sensors in which the sensing nodes are formed by coupling capacitances between respective ones of the X and Y lines, the X lines being driven and the Y lines being connected to at least one charge measurement capacitor for measuring the coupling capacitances. Some embodiments may also be applied to passive or single ended type capacitive touch sensors.
"Various embodiment may be used in a capacitive sensor array with one-dimensional arrays of sensing nodes, such as sliders and scroll wheels, as well as to two-dimensional arrays.
"In one embodiment, the subset of sampled sensing nodes may be restricted to the sensing node at which the touch has been determined to be present and immediately adjacent sensing nodes in at least one dimension, i.e. nearest neighbors. In other embodiments, in particular if the array has a larger number of sensing nodes, the subset may also be extended to more distant neighbors, for example next nearest neighbors, either in one dimension only or in two dimensions in the case of a two-dimensional sensor array."
URL and more information on this patent, see: Yilmaz, Esat; Sleeman, Peter. Capacitive Touch Sensors. U.S. Patent Number 8610009, filed
Keywords for this news article include: Electronics, Microcontroller,
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