Patent Application
20150073741
The present invention relates to a portable electronic device including one or more environmental sensors and a method for measuring an environmental parameter using such a device.
Portable electronic devices for measuring specific environmental parameters such as temperature, pressure, humidity, gas concentrations in the ambient air etc. are well known. With the emergence of smart phones, however, a new class of devices has been more prevalent, which herein is referred to. These devices are characterized in that the measurement of an environmental parameter is not the sole purpose of the device and usually considered an additional or auxiliary task to a main function. The main function is typically a telecommunication function including the capability of communicating with public and private communication networks.
When an environmental sensor is thus integrated in such a general purpose portable device, its operation is subject to constraints very different from the operation of a specialist device for a measurement of the same parameter. In particular, the general purpose device may have to deliver a measurement of the environmental parameter, while positioned or handled in a way often not properly adapted or even detrimental to such a measurement. A typical example is the use of a mobile phone for the measurement of the ambient temperature, which without compensation can give different results depending on whether the phone is placed on a table, held in a hand or placed in a pocket. As during the usage these conditions can rapidly change, an environmental sensor is required to respond rapidly to the changing operational conditions.
It is known for example from the co-owned published United States patent application no. 2011/0307208 A1 that sensors respond to a sudden change with a change determined not only by the change itself but also by their own response function. The '208 application describes a dynamic compensation of this behaviour of the sensor in order to generate results of the measurements in shorter time than would be possible by simply waiting until the sensor reaches a new steady state.
Whilst accelerating the response time of an environmental sensor through a dynamic compensation process can alleviate some of the difficulties faced when operating such a sensor in a portable device, it is found that changes in the operating conditions are often too fast for dynamic compensation alone, which can become unstable or too slow.
Therefore it is seen as an object of the invention to further improve the operation of environmental sensors in portable electronic devices, particularly in general purpose electronic devices.
In accordance with an aspect of the invention there is provided a portable electronic device with one or more integrated environmental sensors for measuring an environmental or ambient parameter, a compensator generating a time sequence of values used as input to the compensator in a following time step for reducing the difference between the environmental sensor output and the actual value of the environmental parameter, and a context evaluator for determining a context of the device and a re-initializator reinitializing the compensator by changing the input from the calculated value to a value depending on a context of the device as determined by the context evaluator.
The value depending on the context can be a value as calculated at a time prior to a change in context or it can be an adapted value or a newly generated value. Independent of the type of change, the changed input is derived in accordance with the result of the evaluation of the context evaluator.
The re-initialization can be seen changing an input value for the compensator from a value as calculated in the normal operation of the compensator to a value as adapted or changed depending on a context of the device as determined by the context evaluator.
As the input for re-initialization when selected correctly reflects better the changed conditions, in which the device is found, the changed value of the environmental parameter can be displayed faster than using the compensator with its normal unchanged input value.
The environmental sensor can be a temperature, a humidity, a chemical, gas, or pressure sensor. It is generally designed to measure an ambient parameter relating to a condition exterior of the housing of the device. Most of these sensors require an opening or duct in the housing to allow for the exchange of air or other fluids between the exterior and the sensing elements of the sensor. The opening can be covered with a proactive mesh, grill or membrane.
The compensator can include a dynamic compensator used to apply a correction based on a model of the response function of the sensor during a change in the environmental parameter in order to accelerate the readout during such a change or a heat compensator used to apply a correction based on a model of the thermal propagation from heat sources in order to compensate for internal and external heat sources. More preferably the compensator operates under normal operating conditions recursively using state vectors generated at each time step as input for the next time step.
The changes in the environment and/or handling are generally caused by a corresponding change in the external or environmental conditions, also referred to as context conditions, under which the device is operated. Such changes can include a change of location such as a change from indoors (car, building) to outdoors (street), or between two locations with different ambient conditions (such as cellar vs. bathroom) or for example the exposure of the device to sun light, wind and other changing ambient conditions. The change can also be caused by the way the device is handled by a user such as a change from being held to being placed in a pocket or bag.
The change in the context condition is detected by the context evaluator, which typically resides as a programmed routine in part of general purpose computing units. However it can also include either parts of sensor processing units and via a communication links computing units at remote locations. The evaluator can be programmed to a varying degree of complexity or scenarios reflecting the diverse ways in which a portable device is typically used. The complexity can range from simple binary decisions based for example on whether a device is located within a building or outside (which in turn can be derived from a position measurement) to more complex model-based, or statistical evaluation of motion sensors, use pattern and the like to determine whether the device has been placed inside a pocket or bag. Other scenarios can be based on the current physical location (latitude, longitude) and/or semantical location (at home, at workplace) or depend for example on the current use (in communication, or play or video/music replay mode) of the device.
The context evaluator is therefore best linked to the output of sensors integrated into the device. These sensors can include the environmental sensor itself. It can however also include at least one further sensor integrated into the device. However, the change in environmental conditions can in principle also be detected by sensors external to the device and communicated to the device, such as prevalent wind strength and directions, cloud coverage and the like.
The further sensors within the meaning of the present invention can be selected from a group including picture or video cameras, IR sensors, acoustic microphones, location sensors and providers (GPS, Location fingerprinting (WiFi, GSM, network-based)), brightness sensors, ultrasound sensors, proximity sensors, acceleration sensors, Bluetooth receivers, EM wave antennae and orientation sensors, whereby these sensors are preferably integrated into the same housing as the environmental sensor or, alternatively or in addition, sensors which can communicate directly or indirectly, i.e. over a common server, with the portable device, such as external sensors in close proximity, in other mobile devices, consumer electronics and appliances, network connected sources such as internet based weather information, server based information or, alternatively or in addition, be indicators of the state of the device (stand-by, calling, gaming). Sensors to detect the handling can include a touch sensitive surface or screen of the portable device.
The portable electronic device can preferably be a mobile phone, a handheld computer, an electronic reader, a tablet computer, a game controller, a pointing device, a photo or a video camera, a digital music player, a wrist watch, a key fob, a head set, a digital photo frame and a computer peripheral, glasses, a wristband.
Other advantageous embodiments are listed in the dependent claims as well as in the description below. The described embodiments similarly pertain to the device, the method, and any computer program elements. Synergetic effects may arise from different combinations of the embodiments although they might not be described in detail. In particular, a further aspect of the present invention includes a method of determining a context representing the mobile device being in a pocket.
Further all embodiments of the present invention concerning a method might be carried out in the order of the steps as described. Nevertheless this has not to be the only essential order of steps but all different orders of the method steps where technically feasible shall be comprised in the scope of the claims and be disclosed by the method claims.
The detailed description refers to examples of the present invention making reference to the annexed drawings, wherein:
The device of
Another opening 107 is located at the lower side wall. As shown in
In addition to these sensors or alternatively other environmental sensors can be used such as a gas sensors as for example proposed in: M. Afridi et. al. “MEMS-based embedded sensor virtual components for system-on-a-chip (SoC)” Solid-State Electronics 48 (2004) 1777-1781, and can be mounted within the housing 10. The actual size and shape of the duct 11 depends on the volume available and the nature of the temperature sensor 12 and the humidity sensor 13 can vary, but given the physical constraints of portable mobile devices the area of the opening is typically in the range of less than 10 square millimeters and in the present example actually about less than 3.1 square millimeters.
The temperature or other environmental sensors can also be mounted flush with the housing of the phone or even without connection to the exterior.
Further control and read-out function can also be performed by a central processing unit (CPU) 25 of the portable device, which in turn has read/write access to a memory 26, which can include static or volatile memory or both as known in the art. The memory 26 typically stores the operating system of the device and can also be used to store application programs specific to the operation of the sensors of the portable device. The functions performed by the sensor hub 23 and the sensor specific programs and program libraries as stored and executed by the CPU 25 form a temperature processing unit capable of transforming the measurements of the sensor into a result which can be displayed or otherwise communicated to the user of the portable device.
The components and executable code required to perform a dynamic compensation as described for example in the above cited '208 application can reside in the memory 26 and be executed by the CPU 25.
The memory 26 and the CPU 25 can also be used to store and run executable code for a heat compensator applied to the sensor signals to correct the temperature as directly measured to compensate for effects of the surrounding of the sensor inside the portable device or external to it.
Such a compensator includes typically a representation of a model which takes into account heat sources, heat capacities and heat conduction of elements inside the device, its housing and other factors. Based on this model and measurements relating to a present status of the elements, the measured temperature value is corrected before being displayed.
In the present example the CPU 25 and the memory 26 further include and execute a system to determine whether a change in temperature is influenced by a change in the environment or handling of the mobile device. Functions of such a system are described in more detail below while making reference to
In addition to the specific sensors as described above, the CPU is also connected to one or more sensors, for example a camera 271 or a microphone 272 also shown as the camera 106 and the microphone 104 of
The device includes further well known input/output units 281 such as a touch sensitive display, virtual or physical keyboards and gesture tracking devices etc. The portable device as shown has a telecommunication circuit 282 comprising an antenna, driver circuits and encoding and decoding units as are well known in the art. Using such a telecommunication circuit, the device can connect to a public voice and date network and remote locations 29 as shown.
The diagrams of
The block diagram of
The compensation unit 35 as described in the following example performs a dynamic and heat compensation based on a model of the response function of the temperature sensor 31 and thermal propagation from heat sources to the sensor 31. It can be described as a program residing in the memory 26 and using the processing unit 25 of the device. The compensator can generate an estimate of the ambient temperature Ta using a suitable implementation of the following equations [1]:
x(k+1)=Ax(k)+Bu(k)
y(k)=Cx(k)+Du(k)
with u(k) denoting a representation of the reading of the temperature Ts as provided by the sensor 31 at time step k, y(k) denoting the output Ta, and x(k) denoting an internal state vector of the compensator. A is an n-by-n matrix, B an n-by-m matrix, C an 1-by-n matrix and D an 1-by-m matrix, where n is the number of states that depends on the complexity of the underlying model of the response function and m the number of inputs.
At each time step the system takes as input the current sensor reading Ts or u(k) and the internal state vector generated in the previous iteration. Based on the model as represented by the matrix elements A-D the compensator generates at each time step a representation of an estimate of the ambient temperature Ta or y(k) and a new internal state vector x(k+1) which in turn is used as an input for the compensator 35 at the next time step. In effect, the compensator generates a time sequence of internal state vectors x(k+1), represented in
In the example a context evaluator 36 monitors both the context in which the portable device is handled and this sequence of internal state vectors. Based on a relevant change in the context to be described in several examples below, the context evaluator 36 selects or flags an internal state vector effectively resetting the selected state vector to x(k+1), i.e., the input to the compensator.
When the context evaluator 36 later determines that the relevant change to the portable device has been reversed, a re-initializator 37 selects a state vector or recalculates a state vector based on the selected state vector and input signal (371, 372 and 373). The changed state vector is used as input vector x(k+1) (replacing the actual vector as generated by the compensator 35 in the time step) in the following time step. This operation can be regarded effectively as a reinitialization of the compensator 36 with the state vector as determined during the normal operation of the compensator replaced by a changed state vector. This operation of the context evaluator 36 and the re-initializator 37 and the resulting acceleration of the dynamic compensation is described in the following using several examples.
The context evaluator can be based on the past and/or current behaviour of the environmental sensor it controls. By tracking the changes and applying threshold or gradient tests, the context evaluator can select a state vector after registering a significant or steep change in the reading of the environmental sensor. The state vector selected form the stored state vectors can for example be a state vector prior to the occurrence of the change. When the context evaluator registers the onset of a change in the reverse direction the selected state vector can be used in the compensation as described above.
This self-referential control of the environmental sensor can work for changes between indoors and outdoor and the change in for example temperature, humidity, and air composition which can go along with stepping from an indoor location onto a street or into or out of an automobile.
In
However in case that the context evaluator registers the sudden change in temperature, which in the example is assumed to have occurred around a time step t(−5) and flags or selects the state vector at this time step, this value can be reapplied at time t(0), when the reverse step occurs and is again registered by the context evaluator. Using this modified initialization or reset of the compensator the displayed temperature follows curve Ta′ which effectively re-sets the compensator with a state vector representing an ambient temperature of 35° C. (as before the change to the indoor temperature). As a result the re-set compensation Ta′ converges faster towards the real outdoor temperature T(out) of 36° than the normal compensation Ta.
In addition or instead of a self-referential operation the context evaluator 36 can receive inputs from other sensors 371, 372, 373 or other components of the portable device, for example CPU usage or telecommunication activity. Taking for example the change from indoor and outdoor, a GPS or a network enhanced location signal can be used by a suitable indoor/outdoor test of the context evaluator to anticipate a change in the environmental parameter measured and trigger the selection of the state vector valid prior to the change in location. When the location sensor triggers a return to initial location the compensator 35 is reset to the selected state vector.
In further examples the context evaluator can test conditions based on a multitude of sensor readings and activity indicator. To detect for example whether a mobile phone is placed in a pocket or a bag, a combination of proximity sensors, motion sensors, CPU activity, brightness detection, temperature and touch input can be combined in a statistical model predicting whether or not this scenario is true.
To detect for example whether the device is located in a pocket, the proximity sensor can be used to check on a barrier in the immediate proximity of the phone, the light or brightness sensor can be checked for reduced brightness or darkness, the display can be tested for being switched off and a temperature sensor reading can be tested for resulting in a reading close to the surface temperature of the skin (28° C.-40° C.) The upper limit of the temperature takes heating from other (internal and external) sources into account. More specifically a context evaluation as to whether a device is inside or outside a user's pocket can include the following conditions:
If during the period of 10 s the following conditions are true:
These basic conditions can be additionally accompanied by a further test to render the pocket recognition more robust. Such further test can include a temperature measurement or a test on whether the display is switched off. The temperature measurement can use the uncompensated temperature as measured by a temperature sensor in the device and a test on whether this raw temperature is between 28° C. and 40° C. and whether it is rising or at least stable. If these conditions are found to hold, the device is assumed to be in an “in-pocket” mode and the context evaluator initiates the adaptations to the compensator as associated with such a mode.
It should however be understood that such a context test is a probability test and not deterministic as one can never expect to recognize the true context of the device under all circumstances unless making use of direct user feedback in form of for example a direct user selection of a context.
As shown in
It should be noted that for the working of the above example, only those of the state vector or initial conditions selected by the context evaluator need to be stored.
It should be further noted that the state vector or initial condition to reset the compensator can be derived synthetically, i.e., without reference to previous values of the state vector or initial condition as used by the compensator or by using an adapted or modified version of the stored value. Given for example that the outdoor temperature at a given location is approximately known or can be extracted from remote sources such as online providers, the context evaluator can be programmed to request such information and together with the re-initializator generate a corresponding state vector or initial condition for the compensator.
While there are shown and described presently preferred embodiments of the invention, it is to be understood that the invention is not limited thereto but may be otherwise variously embodied and practised within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1564/13 | Sep 2013 | CH | national |
