Patent Application
20230368655
The present invention relates to an apparatus and method for determining the validity of an infrared signal of a remote-control device.
An infrared (IR) remote-control device for wirelessly controlling an electronic appliance such as a television or air-conditioning unit comprises a plurality of buttons and various electronic components that are configured to generate and transmit an IR control signal to the electronic appliance upon pressing of one of the plurality of buttons. The transmitted IR control signal is encoded with data representing a specific command code that corresponds to the function associated with the pressed button. For example, pressing the volume “up” button of a television remote-control device causes the device to generate and transmit an IR control signal comprising a command code corresponding to the volume up instruction. Thus, when the television receives and decodes the IR signal, the television carries out the instruction to increase the volume.
Each button may be associated with a specific function of the electronic device so that the remote-control device is capable of transmitting multiple different IR control signals, each corresponding to a different function of the receiving electronic appliance.
An IR remote-control device typically comprises an elongate body that houses electronic components including an integrated circuit and near infrared diode. The plurality of buttons extend through a wall of the housing and are arranged, upon pressing of a button, to contact the integrated circuit via corresponding button contacts. When a button is pressed, the remote device uses an encoder to convert a binary signal (representing the function of the pressed button) into a modulated electrical signal which causes the transmitting diode to convert the modulated electrical signal into a modulated IR light signal comprising a series of IR light pulse bursts switched on and off at a high frequency (the carrier frequency).
The receiver diode of the target appliance detects the IR light pulses and permits the passage of IR at the carrier frequency so as to filter out unrelated IR light. The target appliance then amplifies the modulated signal with a pre-amplifier and converts it to a binary signal before sending it to an MCU to identify and implement the requested function.
The pattern in which the modulated IR signal is converted to binary is defined by a transmission protocol which varies by brand. For example, the IR light signal may implement Manchester encoding (used by the Philips® brand) or the more common pulse-distance coding (used by Japanese brands such as NEC® and Sony®).
In the case of a Manchester encoding implemented in the Philips® RC5 protocol, a binary code is achieved by encoding every data bit with a transition from a HIGH to LOW, or LOW to HIGH. A transition from a HIGH to LOW or falling edge may represent a logical “1” and a transition from LOW to HIGH or rising edge may represent a logical “0”.
In the case of a pulse-distance coding, the modulated IR signal comprises a series of pulse bursts of specific length each representing a single bit and comprising a HIGH “carrier” pulse and a LOW “no carrier” space. The combined length of the HIGH pulse and LOW space determines whether a single pulse burst represents a logical “1” or logical “0”. For example, a logical “1” may correspond to a pulse burst comprising a short HIGH pulse followed by a long LOW space, and a logical “0” may correspond to a pulse burst comprising a short HIGH pulse followed by a short LOW space that is half the time period of a long LOW space.
Many electronic appliances have their own dedicated remote-control device. For example, a television will typically have its own remote-control device and a DVD player or digital set top box may likewise have its own remote-control device. Consequently, there may be several remote-control devices in any one household. This is frustrating and inconvenient for the users because of the need to switch remote-control devices depending on the household appliance to be controlled.
This problem has been largely addressed by universal remote-control devices which are capable of controlling many different types and brands of household electronic appliances. Accordingly, multiple, standalone remote-control devices may be conveniently replaced by the single universal remote-control device.
However, there are no agreed standards for IR codes and their corresponding functions. For example, two brands may have their own bespoke protocols such that the on/off command code of one brand is different from the on/off command code of another brand. This is problematic for a universal remote-control device which is intended to control multiple different devices regardless of the manufacturer.
Universal remote-control device manufacturers have attempted to address this problem by reverse engineering the codes of different brands to build a library of IR codes. This library may be stored in the memory of the universal remote-control device so that the device can identify the correct set of IR codes for a given electronic appliance. The IR code identification process involves first transmitting an IR signal of a specific function from the relevant standalone remote-control device (the “transmitting device”) to the universal remote-control device (the “receiving device”) for receipt and decoding. Upon receipt and decoding of the IR signal, the receiving device compares the command code of the IR signal with the stored library of IR codes and, if a match is found, identifies the correct protocol required to replicate the IR codes of the transmitting device so that the receiving device can likewise control the corresponding electronic appliance.
Since the IR library may not include all known IR codes and protocols, the receiving device may also be equipped with a learning function, whereby the receiving device can be programmed to store the IR code of a received IR signal in memory and associate that code with a button and a corresponding function of the relevant electronic appliance.
However, a problem with using infrared for wireless communication and control is that the received IR signal can be tainted by noise or noise-like artifacts. This “noise” may be due to background white noise emitted by other IR devices, warm bodies, or sunlight. Alternatively, or additionally, movement of the transmitting device relative to the receiving device during transmission can introduce noise-like artifacts into the IR signal. This creates difficulties in determining whether a received IR signal is valid and can be stored as a command code for subsequent use.
Consequently, a learning procedure by a universal remote-control device should preferably be conducted indoors without direct sunlight and without other IR transmitting devices in proximity, and also with a fixed distance between the transmitting and receiving devices without any relative movement.
In practice, though, users tend to hold one or both devices when implementing the IR learning mode and this inherently leads to unwanted noise or noise-like artifacts in the received IR signal. This creates difficulties in determining whether a received IR signal is a valid signal whose corresponding code may be stored for subsequent performance of the corresponding function by the target appliance.
It is an object of the present invention to mitigate the above identified problems and to improve the ability of a receiving control device to determine the validity of a received IR signal despite the presence of noise or noise like artifacts.
In accordance with a first aspect of the present invention, there is provided a method of determining the validity of an infrared signal of a remote-control device comprising the steps of:
Advantageously, by comparing the discharge sequence associated with the infrared signal with pre-determined discharge patterns it is possible to determine whether the received IR signal is valid and, hence, suitable for storage or locating a code match in a code library for subsequent control of a target electronic device.
The method may further comprise the steps of decoding the infrared signal and storing the decoded data of the infrared signal in memory upon finding a match between the established discharge sequence and a pre-determined valid discharge pattern of the plurality of pre-determined valid discharge patterns.
The method may further comprise the step of prompting a user to retransmit the infrared signal of the remote-control device upon failing to find a match between the discharge sequence and a pre-determined valid discharge pattern of the plurality of pre-determined valid discharge patterns.
The method may further comprise the step of demodulating the infrared signal before passing the infrared signal through the capacitor.
Each pre-determined valid discharge pattern of the plurality of pre-determined valid discharge patterns may comprise a range of valid discharge times corresponding to each pulse of the received infrared signal, and wherein the step of determining the validity of the received infrared signal comprises comparing each discharge time of the established discharge sequence with the range of valid discharge times of the corresponding pulse of each pre-determined valid discharge pattern of the plurality of pre-determined valid discharge patterns.
According to a second aspect of the present invention, there is provided an apparatus for determining the validity of an infrared signal of a remote-control device comprising
The processor may be further configured to decode the infrared signal and store the decoded data of the infrared signal in memory upon finding a match between the established discharge sequence and a pre-determined valid discharge pattern of the plurality of pre-determined valid discharge patterns.
The processor may be further configured to prompt a user to retransmit the infrared signal of the remote-control device upon failing to find a match between the discharge sequence and a pre-determined valid discharge pattern of the plurality of pre-determined valid discharge patterns.
The apparatus may further comprise a demodulator configured to demodulate the infrared signal before passing the infrared signal through the capacitor.
According to a third aspect of the present invention, there is provided a method of storing a valid discharge sequence related to an infrared signal transmitted by a remote-control device, the infrared signal comprising a plurality of pulses representing data corresponding to a function of a controllable target device, the method comprising the steps of:
The method may further comprise the step of storing one or more additional discharge sequences for the same infrared signal.
The method may further comprise the step of establishing a valid discharge pattern based on the or each stored sequence of discharge times.
A valid discharge pattern may comprise a range of valid discharge times associated with each pulse of the infrared signal.
The method may be repeated for one or more different infrared signals to build a database of valid discharge patterns.
According to a fourth aspect of the present invention, there is provide an apparatus for determining one or more valid discharge sequences associated with an infrared signal comprising a plurality of pulses representing data corresponding to a function of a controllable target device, the apparatus comprising
The computing device may be configured to process and store multiple discharge sequences of an infrared signal.
The computing device may be configured to control the means for producing the relative movement to produce a known relative movement pattern between the transmitting device and the infrared receiver.
The apparatus may further comprise means for measuring the distance between the transmitting device and the infrared receiver. The means for measuring the distance may comprise a LiDAR sensor. The computing device may be configured to store the location of the transmitting device for each measured discharge time associated with each pulse of the demodulated infrared signal.
In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which:
Referring to the drawings there is shown a schematic representation of elements of a universal remote-control device 1 that is programmable to transmit wireless command signals in the form of infrared (IR) light to a plurality of different target controllable electronic appliances (not shown) such as a television, DVD player, digital set-top box, or air conditioning unit. The universal remote-control device 1 comprises a processor 3, memory 5, a plurality of buttons 7, and circuitry 9 forming a button matrix in relation to the plurality of buttons 7.
Each of the buttons 7 may be associated with a function of the target controllable device and data of the command code for the desired function may be stored in the memory 5 so that, when a particular button is pressed by a user, the appropriate command code is encoded onto the IR light signal and transmitted to the target device for implementation.
Referring to
To enable wireless communication between devices, the universal remote-control device 1 comprises a wireless communications interface 11 for transmitting and receiving IR signals with the data representing command codes for the target controllable device. The wireless communications interface comprises a diode 13 capable of transmitting data in the form of IR light, an encoder 15 for encoding the IR light with data of a command code, an IR sensor 17 for detecting and receiving wirelessly transmitted IR signals, and a decoder 19 for decoding a received IR signal for subsequent processing by the processor 3.
The memory 5 stores an IR library that comprises multiple sets of commands codes for different brands and appliances. Accordingly, the universal remote-control device 1 may be configured to operate different target appliances by identifying the appropriate set of command codes for a given target device and loading the data set into the working RAM memory of the remote-control device 1 such that the buttons 7 trigger the correct command for subsequent wireless control of the target appliance.
Referring to
To improve the ability of the receiving controller 1 to determine the validity of a received IR signal and, hence, whether to conduct a match routine or to store the command code as a valid code for subsequent control of the target appliance, the wireless communications interface 11 comprises an AC coupling circuit 23 with a capacitive element coupled to the processor and arranged between the IR sensor 17 and the processor 3 so that the demodulated IR signal and, hence, each pulse of a received IR signal is routed through, and charges, the capacitive element of the AC coupling circuit 23 in sequence. The size of the capacitive element is chosen to be sufficiently small such that the capacitive element has fully discharged between each consecutive pulse. Accordingly, the required size of the capacitive element is determined by the sensitivity of the IR sensor 17 and the transmission power of the IR transmitter of the transmitting controller 21. In the present embodiment the capacitive element is chosen to have a capacitance of 470 pF but could be in the range between 20 pF and 500 pF depending on the aforementioned variables.
The capacitive element of the AC coupling circuit 23 has the effect of removing the DC component of the IR signal, which typically contains the majority of the background noise, and of identifying each discrete binary pulse as a charge/discharge cycle. As shown in
When the distance between the transmitting controller 21 and the receiving controller 1 is constant and a good IR signal is received by the receiving controller 1, the charge/discharge cycle associated with each pulse is stable and consistent. Accordingly, the discharge time D1, D2, D3, D4 of the capacitive element for each pulse is substantially the same. Referring to
Since the IR reception power increases as the distance between the transmitting and receiving controllers decreases, the discharge time of the capacitive element increases as the distance between the transmitting and receiving controllers decreases. Consequently, the charge/discharge cycle associated with each pulse varies with relative separation between the transmitting and receiving controllers.
Where the relative separation between the transmitting and receiving controllers increases during transmission of the IR signal, the charge/discharge cycle for each consecutive pulse decreases. As shown in
It will be appreciated that different relative movement patterns between the transmitting and receiving controllers will produce different discharge sequences. For example, an increasing slope followed by a decreasing slope or an approximately “n” shaped slope will correspond to an initial decrease in distance followed by an increase in distance between the transmitting and receiving controllers. Conversely, in another example, a decreasing slope followed by an increasing slope or an approximately “u” shaped slope will correspond to an initial increase in distance followed by a decrease in distance between the transmitting and receiving controllers.
By obtaining discharge sequences for different relative movement patterns between the transmitting and receiving controllers, it is possible to build a library of pre-determined discharge patterns that can be used when analysing a received IR signal and establishing its validity for further processing and storage. Accordingly, the receiving controller 1 stores a discharge pattern library in memory 5 to enable the processor 3 to determine whether noise or noise-like artifacts present in the IR signal are due to the relative movement between transmitting and receiving controllers or due to other background noise such as sunlight and/or other nearby IR devices.
The discharge pattern library may be populated with different pre-determined discharge patterns that have been pre-captured in a testing environment. The testing environment may comprise a test jig for securing a test transmitting controller and allowing adjustment of the 3D spatial position of the test transmitting controller relative to an IR receiver. In the present example, the test jig comprises three motors for automatically moving the test transmitting controller in 3D space according to movement commands from a test computing device.
The test jig includes a LiDAR sensor to continuously measure the distance between the test transmitting controller and the IR receiver so that the position of the test transmitting controller relative to the IR receiver can be measured in real-time and fed back to the test computing device. The test transmitting controller is set to transmit with an IR transmission power that is typical for IR remote control devices. The test transmitting controller and test jig are set within an enclosure having walls coloured in grey, black, and white to emulate the IR reflections of a typical room environment. The test computing device is connected to the IR receiver and capacitor and is configured to demodulate the IR signal and measure the capacitor discharge time associated with sequential pulses of the demodulated IR signal.
Referring to
Accordingly, a first test discharge sequence may be obtained by first positioning the test transmitting controller at a starting 3D coordinate of the test jig i.e., [0, 0, 0]. The test transmitting controller is then activated to transmit an IR signal of a specific command of a target device such as the on/off command. Simultaneously, the test jig is instructed by the test computing device to automatically move the test transmitting controller through different 3D coordinates so that the IR signal is transmitted during relative movement conditions. In the example of
The analysing computing device receives the demodulated IR signal via the IR receiver and capacitor and measures the discharge time, 3D coordinate, and discharge count for the sequential pulses of the IR signal. Since the command associated with a button is transmitted three times in succession for each button press, the testing environment captures a further two consecutive sequences of discharge counts of the IR signal during further relative movement between the test transmitting controller and the IR receiver. Using the three captured sequences of discharge counts it is possible to construct a pre-determined discharge pattern for the IR signal of a given button command comprising a range of valid discharge counts for each pulse of the IR signal with a count minimum and a count maximum.
Referring to
In the example depicted, the count_minmax for each pulse of an IR signal is established using the lowest discharge count and highest discharge count of the three consecutive IR signals of a given button press. It will be appreciated also that a pre-determined discharge pattern may also be constructed by averaging the discharge count of each common pulse of the three consecutive IR signals of a button press and creating upper and lower bounds by adding, for example, ±5% to the average discharge count associated with each pulse. The established pre-determined discharge pattern for the specified button command may be depicted graphically over time with upper and lower range bounds in the form of a chart as shown in
By repeating the above process for different button commands across through different relative movement patterns between the transmitting and receiving controllers, it is possible to build a library of valid pre-determined discharge patterns. In the present example, it is deemed sufficient to repeat the test process for a given controller three times with different button commands in order to establish a library with sufficient discharge patterns for IR signal validity matching. However, it will be appreciated that more or less discharge patterns may be captured as desired, but at least three is preferable.
The library of discharge patterns may be subsequently used when conducting a pattern match routine by the receiving controller to determine the validity of a received IR signal. Referring to
Referring to
Referring to
The above embodiment is described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 32022053446.7 | May 2022 | HK | national |
