Abstract:
A wireless control and pointer system for controlling electronic equipment. The system generally includes a hand held remote control comprising a first infrared signal emitter for use in transmitting a first infrared signal comprising a plurality of signal components each of which is transmitted at a first frequency but out of phase with respect to the other of the plurality of signal components and a receiver comprising an infrared signal sensor adapted to receive the infrared signal, a circuit connected to the infrared signal sensor for generating an orientation signal indicative of the orientation of the remote control as a function of the amplitude of each of the plurality of signal components of the infrared signal, and an interface circuit for transmitting a command signal indicative of the orientation signal to the electronic equipment.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to wireless control of electronic equipment and, more particularly, relates to a hand held remote control and pointer device capable of controlling the operation of an electronic component which may include the movement of a cursor displayed on a display screen of an electronic component such as a personal computer, a television receiver, or the like. 
     In the art, various systems for providing wireless control of electronic equipment have been proposed. An example of one such system may be seen in U.S. Pat. Nos. 4,745,402 and 4,796,019 to Auerbach. These patents both disclose a system using a remote control transmitter having the capability for controlling the movement of a cursor displayed on a display screen of an electronic device as well as the capability for controlling the operation of the device itself. The control of the cursor is disclosed to be a function of a perceived change in the angular position of the remote control while the control of the electronic device is disclosed to be a function of transmitted, dedicated, function data. More particularly, the angular position information is described as being a function of the phase angle and amplitude of the resultant of the combined signals transmitted from the energized LEDs of the remote control. 
     A further example of a wireless control and pointing system may be found in co-pending U.S. patent Ser. No. 08/605,546 entitled “System For Providing Wireless Pointer Control” filed on Feb. 26, 1996 in the name of Marcus Escobosa and assigned to the assignee of the subject invention. The &#39;546 application discloses a system including a remote control pointer device capable of generating a signal having multiple signal components with different frequencies and a base station capable of receiving and decoding the signal. The base station interprets the multiple signal components to determine the orientation of the remote control pointer device to properly generate a pointer control signal for properly selecting a particular piece of equipment to receive remote commands or data, and where appropriate, properly displaying and positioning a cursor displayed on the electronic equipment. To assist in an understanding of the subject invention, the full disclosure found in the &#39;546 patent application is hereby incorporated by reference in its entirety. 
     While the wireless command and pointing systems described above provide a means for controlling the operation of an electric appliance in conjunction with the ability to control the movement of a cursor displayed on a display screen, it is a general object of the present invention to provide an improved wireless command and pointer system having the capability to control the operation of an electric appliance in conjunction with the ability to control the movement of a cursor with a relatively higher degree of precision than found in the prior art. It is further object of the present invention to provide a wireless pointer capable of preventing a cursor from being vibrated due to unintentional movement of the hand of an operator. It is yet another object of the present invention to provide a wireless pointer system in which frequency interference resulting from electrical lighting is minimized. It is still a further object of the present invention to provide a wireless pointer in which a lens allows for the transmission of an improved radiation pattern. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a wireless control and pointer system for controlling electronic equipment is provided. The system generally includes a hand held remote control comprising a first infrared signal emitter for use in transmitting a first infrared signal comprising a plurality of signal components each of which is transmitted at a first frequency but out of phase with respect to the other of the plurality of signal components and a receiver comprising an infrared signal sensor adapted to receive the infrared signal, a circuit connected to the infrared signal sensor for generating an orientation signal indicative of the orientation of the remote control as a function of the amplitude of each of the plurality of signal components of the infrared signal, and an interface circuit for transmitting a command signal based upon the orientation signal to the electronic equipment. 
     In another embodiment of the invention, the system includes a hand held remote control comprising a plurality of LEDs for use in transmitting an infrared signal comprising a plurality of separately identifiable signal components and a lens for modifying the radiation pattern emitted by each of the plurality of LEDs where the intensity of the radiation pattern is seen to be a function of angle with respect to the central axis of each of the plurality of LEDs and a receiver comprising an infrared signal sensor adapted to receive the plurality of separately identifiable signal components, a circuit connected to the infrared signal sensor for generating an orientation signal indicative of the orientation of the remote control in response to a characteristic of the plurality of separately identifiable signal components, and an interface circuit for transmitting a command signal based upon the orientation signal to the electronic equipment. 
     In a further embodiment of the invention, the system generally comprises a hand held remote control comprising a infrared signal emitter for use in transmitting an infrared signal comprising a plurality of separately identifiable signal components and a means for synchronizing the transmission of the plurality of separately identifiable signal components to an external interference signal and a receiver comprising an infrared signal sensor adapted to receive the plurality of separately identifiable signal components, a circuit connected to the infrared signal sensor for generating an orientation signal indicative of the orientation of the remote control as a function of a characteristic of the plurality of separately identifiable signal components, and an interface circuit for transmitting a command signal based upon the orientation signal to the electronic equipment. 
     A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth an illustrative embodiment and are indicative of the various ways in which the principles of the invention may be employed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the invention, reference may be had to the preferred embodiment shown in the following drawings in which: 
     FIG. 1 illustrates a perspective view of a receiver which receives a pointer control signal which is supplied for the purpose of controlling an electric device and/or for controlling the movement of a displayed cursor; 
     FIG. 2 illustrates a perspective view of the hand held, remote control capable of generating the pointer control signal received by the receiver illustrated in FIG. 1; 
     FIG. 3 illustrates a ray tracing resulting from the use of one of the LED and lenses illustrated in FIG. 2; 
     FIG. 4 illustrates a radiation pattern emitted by one of the LEDs and lenses illustrated in FIG. 2; 
     FIG. 5 illustrates a block diagram schematic of the hand held, remote control of FIG. 2; 
     FIG. 6 illustrates a timing diagram of the signals which comprise the orientation determining signal emitted by the multiple LEDs of FIG. 3; 
     FIG. 7 illustrates a block diagram schematic of the receiver of FIG. 1; 
     FIG. 8 illustrates a block diagram schematic of the adaptive gesture filter of FIG. 7; 
     FIG. 9 illustrates a block diagram schematic of the movement thresholding comparator circuit of FIG. 7; 
     FIG. 10 illustrates a cross-sectional side view of one of the lenses illustrated in FIG. 2; 
     FIG. 11 illustrates a front plan view of one of the lenses illustrated in FIG. 2; and 
     FIG. 12 illustrates a bottom plan view of one of the lenses illustrated in FIG.  2 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to the figures, wherein like reference numerals refer to like elements, there is illustrated in FIG. 1 a perspective view of a receiver  10 . The receiver  10  is used to supply a control signal to a device, illustrated as a television set  12 , being pointed at and/or to control the movement of an electronically displayed cursor. The receiver  10  is preferably placed proximate to the screen  14  or display of the electronic device and includes a sensor  16  for receiving transmitted information from a remote control  18 , shown in FIG. 2, which includes user actuatable buttons  20 , 22 , 24  and  26 . While the user actuatable buttons  20 , 22 , 24 , and  26  are illustrated as relating to cursor control, e.g. select, drag, drop, etc., it will be understood that the user actuatable buttons may also be related to ordinary electronic appliance control functions, e.g. channel up, channel down, volume, mute, play, rewind, etc. As will be described in greater detail hereinafter, the control of the electronically displayed cursor and/or the control of the electronic device is a respective function of the perceived orientation of the wireless pointer or remote control  18  and/or the transmission of function data from the remote control  18  to the receiver  10 . 
     Positioned in the front  28  of the remote control  18  is a signal generating element  32  which is used to transmit the wireless positioning data to the receiver  10 . In the preferred embodiment, the signal generating element  32  comprises four infra-red light emitting diodes (LEDs)  34 ,  36 ,  38  and  40  over each of which is preferably fitted a lens  30  which is used to modify the radiation pattern. Specifically, as illustrated in FIG. 4, each of the lenses  30  function to modify the radiation pattern which is normally emitted by the LED so that intensity is a function of angle with respect to the LEDs central axis. In this manner, the intensity on one axis will vary with angle, while the intensity on the orthogonal axis remains nearly constant. Each of the four LED/lens combinations will have the radiation pattern illustrated in FIG. 4 excepting that each is rotated in increments of 90 degrees from the other diodes. 
     The LEDs/lenses are further grouped into pairs wherein LED  34  is paired with LED  40  and LED  36  is paired with LED  38 . More specifically, one pair of LEDs is provided to allow the tracking of the orientation of the remote control  18  moving up or down while the other pair of LEDs is provided to allow the tracking of the orientation of the remote control  18  moving side to side. In the preferred embodiment, the up and down LEDs have their radiation patterns of FIG. 4 orientated at 0 and 180 degrees respectively while the left and right LEDs have their radiation patterns of FIG. 4 orientated at 90 and 270 degrees respectively. Angular position is determined by the relative intensities of the LEDs as received by the receiver  10 . When transmitting position data, which may be continuous or in response to activation of a button/switch on the keypad  44 , each LED  34 , 36 , 38  and  40  transmits a signal which is split into four phases among each of the LEDs. By way of example, the up and down LEDs transmit the signal with phase shifts of 0 degrees and 180 degrees respectively while the right and left LEDs transmit the signal with phase shifts of 90 degrees and 270 degrees respectively. Since each of the LEDs is differentiated from the other by phase, both amplitude and phase carry the positioning information. 
     The desired intensity curve of the radiation pattern is generated by causing most of the light emitted from the LED to cluster toward one end, with a nearly linear intensity fall off occurring as the lens  30  is viewed from the other end. A ray tracing of this intensity pattern may be seen in FIG.  3 . As illustrated, the area with the closest spaced light rays will be the brightest area while the area with the farthest spaced light rays will be the least brightest area. In order to achieve these approximate radiation patterns from the LEDs, the lens  30  is generally curved in one direction and is generally flat in the other. The flatness allows the radiation pattern to be stable given variations in diode manufacturing and lens manufacturing. This stability is not presently available in those lenses currently utilized which are generally described as being curved in both directions. 
     In the preferred embodiment of the invention, the lens  30  is constructed from a plastic material such as clear acrylic or clear polyurethane (e.g. Synclair Corporation&#39;s polyurethane sold under the trademark “CLEARCAST”) while each of the LEDs is preferably mounted within a lens  30  using an adhesive having substantially the same index of refraction as the material from which the lens is constructed. The lens  30  is shown in greater detail in FIGS. 10-12. It is to be understood that the four lenses  30  may be manufactured as a unitary piece or as four separate pieces without departing from the spirit of the subject invention. Similarly, the lenses need not be arranged in the linear orientation shown and the positioning of each of the lenses may be interchanged while maintaining the desired radiation patterns. 
     Turning to FIG. 5, the electrical components from which the remote control  18  is comprised are illustrated in greater detail. As illustrated, the remote control  18  comprises a CPU  42  having a storage device for storing program instructions and program data, a keypad  44  (supporting buttons  22 ,  24 ,  26  and  28 ), positioning LEDS  34 , 36 , 38 , and  40 , command data LED  46 , and driver circuits  48 ,  50 ,  52 ,  54 , and  56 . In addition, the remote control  18  is preferably equipped with an optional, optical sensor  57  that allows the remote control  18  to detect and ultimately synchronize to the interference signal that typically comes from florescent lights. Specifically, the interference is generated when florescent lights turn on and off at twice the rate of the electrical power. In the U.S., where the wall power frequency is 60 Hz, the florescent lights will turn on and off at a rate of 120 Hz while in other European/Asian countries, where the wall power frequency is 50 Hz, the florescent lights will turn on and off at a rate of 100 Hz. If there exists such an interference signal, the output of the sensor  57 , typically a photo diode, is fed to the CPU through an amplifier and low pass filter so that the CPU will see the interfering 100 Hz or 120 Hz signal. The CPU then utilizes a 2nd order DSP phase locked loop (PLL) to synchronize to the interfering signal. In this way, the positioning signal and position reference signal may also be phase locked to the interference signal such that position updates occur on integer multiples of the 50 Hz or 60 Hz periods. For this purpose, the frequency of the positioning signal and position reference signal are preferably selected to be multiples of one another and the two typical interference signals. While not limiting, the frequencies selected were 2400 Hz and 1200 Hz for the positioning and position reference signals respectively. 
     The type of interference that the PLL helps to eliminate is a very slow cursor rocking action. Specifically, if there is a small difference between the update rates and the 50 Hz or 60 Hz noise signal, there will result a small but noticeable noise difference that is not constant from position update to position update. This small difference will manifest itself as unwanted cursor movement. Since the PLL causes the 50 Hz or 60 Hz noise to be synchronized to the 1200 Hz and 2400 Hz signals, the 50 Hz or 60 Hz periods will not move in time relative to the cursor update rate. The result is an interference which is considered to be constant and, as such, will not result in the differences above-noted which result in unwanted cursor movement. Furthermore, as the base will be seen to be synchronized to the 1200 Hz signal, the base will also be synchronized to the 50 Hz or 60 Hz interference signals. 
     During operation, the CPU generates the orientation determining signal which is comprised of a phase unshifted 1200 Hz square wave (the position reference signal) which is added to each of four phase shifted 2400 Hz square waves ( the phase components of the positioning signal). In other words, the signal on the LEDs is the sum of a 2400 Hz signal at 0, 90, 180 and 270 degrees and the 1200 Hz position reference signal. This addition is performed in the LED drivers  48 ,  50 ,  52 , and  54  which function to amplify the sum of the signals and modulate the directional LEDs. (Reference may be had to FIG. 6 for an illustration of the timing of the signals which comprise the orientation determining signal). It will be understood by those skilled in the art that the reference signal may also be generated utilizing a separate LED. 
     Additionally, for use in transmitting function or command data, typically in response to the activation of a keypad button or switch, the CPU preferably generates a continuous 38.4 KHz signal and a base band button data signal. The button data signal is normally high but is adapted to go low when button data is being transmitted while in the pointing mode. Specifically, the button data is modulated with the 38.4 KHz sub-carrier signal by means of an AND gate which is, in turn, fed to the driver circuit  56  which modulates the command data LED  46 . For the sake of brevity, the specific method by which function data is transmitted will not be discussed further herein. For a complete discussion pertaining to the transmission of function data, the reader is referred to U.S. Pat. No. 4,959,810 which is assigned to the assignee of the subject invention and which is incorporated herein by reference in its entirety. 
     Turning to FIG. 7, the electrical components which comprise the receiver  10  are illustrated. Specifically, the receiver  10  includes a photo diode  60  which is used to receive both the orientation determining signal and button data signal transmitted by the remote control  18 . It will be understood that the button data signal may be sent directly to the electric appliance itself and, in such an arrangement, the photo diode  60  need only receive the orientation determining signal. The signal from the photo diode  60  is preferably amplified and band passed filtered for the purpose of separating the individual 38.4 KHz, 1200 Hz, and the 2400 Hz signals. More specifically, the 1200 Hz and 2400 Hz band pass filters  62 , 64  act as anti-aliasing filters and pre-filters before the 1200 Hz reference signal and 2400 Hz positioning signal are passed to an analog to digital converter (ADC)  66 . Meanwhile, the amplifier  68  is linked to an automatic gain controller (AGC)  70  which monitors the output of the ADC  66 , determines if the signal the ADC  66  sees needs to be amplified or attenuated as compared to a reference, and feeds back to the amplifier  68  a signal which sets the gain of the programmable gain amplifier  68  so that the ADC  66  receives a signal with an optimum amplitude. While the area enclosed in the “analog section” of FIG. 5 are seen to be physical analog circuitry and the functions outside the “analog section” are performed by DSP code residing in the CPU, it is to be understood that this configuration is not meant to be limiting and that those skilled in the art will understand that various other configurations are available to perform the functions described herein. For example, the DSP functions could also be performed by equivalent analog, digital, or switched capacitor circuitry without departing from the spirit of the subject invention. 
     The output of the ADC  66  is fed to a 2400 Hz infinite impulse response (IIR) band pass filter (BPF)  72  and a 1200 Hz IIR BPF  74 . The 2400 Hz filter  72  is very narrow and only passes the positioning signal. As discussed, the 2400 Hz positioning signal is encoded in phase (up, left, down, right) and amplitude (how much up, left, down, right) and, therefore, the signal needs to be split into its four phase components. For this purpose, a phase splitter  76  is linked to the 2400 Hz filter  72  which is adapted to separate the 2400 Hz signal into its 0,90,180, and 270 degree phase components. The 0 and 180 degree phase components are fed to a left/right accumulator  78  while the 90 and 270 degree phase components are fed to a up/down accumulator  80  wherein the phase components are summed. The outputs of the accumulators  78 , 80 , which are a function of the amplitude of the phase signals, are fed to an amplitude normalizer  81  which functions to normalize the outputs of the accumulators  78 , 80  according to the level of the 1200 Hz reference signal which is also fed the amplitude normalizer  81  from the 1200 Hz filter  74 . This is done to ensure that the sensitivity of the receiver  10  to the angular motion of the remote control  18  will be the same as the remote control  18  moves closer or farther from the receiver  10 . 
     The 1200 Hz filter  74  is similarly a narrow filter that only passes the reference signal. However, since the 2400 Hz positioning signal is sent as phase and amplitude relative to the 1200 Hz reference signal, the 1200 Hz signal is preferably phase locked to ensure that the 1200 Hz can be properly used as a reference. Accordingly, the clean, filtered 1200 Hz signal is fed to a 2nd order PLL  82  that is used to accurately track the phase and frequency of 1200 Hz signal transmitted from the remote control  18 . Due to the filter  74  positioned in front of the PLL  82 , the PLL has a 4th order stability function. The PLL  82  is linked to the ADC  60  and is used to regulate the sample timing of the ADC  60 . This regulated timing allows the position processing componentry to extract meaningful phase information. 
     More specifically, the PLL  82  is comprised of a phase error detector  84 , frequency error estimator  86  and a sample clock  88 . The phase error detector  84  determines if there is a phase difference between the internal clock and the reference signal. The phase error detector  84  outputs the direction of this error to the frequency error detector  86  which uses the phase tracking information received from the phase error detector  84  to determine if a frequency correction is necessary. In particular, if the phase error detector  84  outputs a net phase lag error, the frequency error detector  86  will function to increase the tracking frequency. If the phase error detector  84  outputs a net phase lead error, the frequency error detector  86  will function to decrease the tracking frequency. Linked to both the phase error detector  84  and the frequency error detector  86  is the sample clock  88  which takes the outputs from the phase error detector  84  and the frequency error detector  86  to determine the correct tracking frequency and phase of a 9600 Hz sampling clock. As discussed, the output of the sample clock  88  is fed back to the ADC  60  for use in timing the sampling of the positioning and reference signals. 
     The output of the amplitude normalizer  81  comprises an X component (indicative of right left orientation) and a Y component (indicative of up-down orientation). This orientation information is fed to an adaptive gesture filter  90  for further processing. In particular, the adaptive gesture filter  90  is adapted to provide maximal low pass filtering when the user is making relatively small and slow orientation changing movements of the remote control  18  and minimal low pass filtering when the user is making relatively large and fast orientation changing movements of the remote control  18 . This adaptive filtering allows the X and Y orientation components to approximately linearly track the orientation of the remote control when such small and slow movements are being made and allows the X and Y orientation components to non-linearly track the orientation of the remote control when such large and fast movements are being made. In other words, this adaptive filtering allows a cursor shown on the display  14  to linearly track small movements of the remote control  18  thereby providing the user with the ability to precisely position a cursor shown on the display  14 . Meanwhile, fast sweeping movements of the remote control  18  will cause the cursor shown on the display  14  to move over a somewhat larger line than that actually experienced by the remote control  18  thereby providing the user with the ability to imprecisely but quickly move the cursor over large distances about the display  14 . 
     Turning to FIG. 8, the adaptive gesture filter  90  is shown in greater detail. As discussed, the input of the adaptive gesture filter  90  is the raw X and Y orientation data received from the amplitude normalizer  81 . This raw X and Y orientation data is further filtered utilizing a pair of self adaptive, variable IIR low pass filters  92 , 94  which are utilized to provide the aforementioned user comfort. Specifically, when relatively fast/large movements of the remote control  18  are detected the filters are set to have a wide bandwidth and when relatively slow/small movements of the remote control  18  are detected the filters are set to have a narrow bandwidth. It is preferred that the switching between large and narrow bandwidths be done with a delay to avoid cursor skipping which tends to result if immediate switching between narrow and wide bandwidth low pass filtering is done. 
     To control the delay in switching between the narrow and wide bandwidths, the output of the filters  92 , 94  are passed to summers  96 , 98  which determine the difference between the filtered X or Y orientation data and the raw X or Y orientation data. The absolute value of the differences between the filtered X and Y orientation data and the corresponding raw X and Y orientation data are further passed to a summer  100  and fed to a IIR low pass filter  102  which filters and removes any noise or spike differences. The output of the low pass filter  102  is a true delay value which is comprised of the combined, filtered differences between the filtered X and Y orientation data and the corresponding raw X and Y orientation data. This true delay value is fed into a movement threshold comparator  104  where the true value delay is compared against at least one predetermined threshold delay. A relatively small difference in the true value delay as compared to a predetermined threshold delay is indicative that the filtered X or Y orientation data is tracking the remote control  18  correctly while a relatively large difference in the true value delay as compared to a predetermined threshold delay is indicative that the filters  92 , 94  are delaying the output by an unacceptable amount. If the delay is determined to be to relatively large, the movement threshold comparator  104  causes the X and Y IIR lowpass filters  92 , 94  to switch to a wide bandwidth. If the delay is determined to be relatively small, a span of time will pass in the delay function  106  before the X and Y IIR lowpass filters  92 , 94  are set to a narrow bandwidth. 
     The filtered X and Y orientation data are next processed by a movement thresholding circuit  108 . The movement thresholding circuit  108 , seen in FIG. 9, functions to keep minor movements due to noise or shaky hands to be ignored. Specifically, the newly filtered X and Y orientation data are each compared against their respective currently held X and Y orientation data the absolute value differences of which are each summed and compared in a second movement threshold comparator  110  against at least one second predetermined movement threshold value. If the comparison indicates that the position difference is greater than the second predetermined movement threshold value the currently held X and Y orientation data in the holding registers  112 , 114  is changed to the newly filtered X and Y orientation data. However, if the comparison indicates that the position difference is less than the second predetermined movement threshold value the currently held X and Y orientation data will remain unchanged in the holding registers  112 , 114 . The values thus stored in the holding registers  112 , 114 , along with the button press/function data, is thereafter formatted and sent to the electronic device  12  via a RS232 formatter  116  which functions to break the final X orientation, Y orientation, and function data into blocks of bytes which are transmitted by toggling an I/O pin on the CPU  42 . 
     In an alternative embodiment of the subject invention, a sub-carrier may be used on either or both of the 1200 Hz and 2400 Hz signals. In this embodiment, the remote control is modified so that the 1200 Hz and 2400 Hz signals are and-gated with a higher frequency signal such as a 38 KHz or 455 KHz signal while the base is modified to have an appropriately tuned front end, high frequency receiver and a demodulator for use in recovering the 1200 Hz and 2400 Hz baseband signals. This approach allows the signaling to occur in a frequency spectrum that has far less florescent light interference. 
     In a further embodiment of the signaling method undersampling may be utilized. In this embodiment, the remote control is modified to allow for the transmission of a reference and/or positioning signal which has been sub-carrier modulated to a higher frequency. Meanwhile the front end of the receiver is adapted to receive the higher frequency transmission. The received signal is then fed directly to the ADC without demodulation. Since the ADC samples the signal at a rate below the sub-carrier, the sub-carrier and reference and/or positioning signals are aliased back in band. Again, such an approach allows the signaling to occur in a frequency spectrum that has far less florescent light interference while eliminating the costs associated with the use of a demodulator circuit. 
     In another embodiment of the subject invention, the lens  30  is replaced with a ground glass and smoked glass arrangement which is adapted to generate the radiation pattern described previously. Since LEDs have some undesirable radiation pattern attributes which include unit to unit variations in radiation pattern and intensity, a sheet of ground glass and smoked glass, having a varying amounts of absorption in one direction and a constant amount of absorption in the orthogonal direction, are placed in front of the LED to fix the patterns. Specifically, the ground glass is used to scatter the light emitted by the LED evenly in all directions whereafter the smoked glass sheet functions to generate the desired radiation intensity pattern. 
     While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any equivalent thereof.