POSITION SENSING CONTROLLER AND METHOD FOR GENERATING CONTROL SIGNALS

Abstract: An improved position sensing controller (40) allows a person to precisely control the movement of a remote object or device in one or two dimensions by simply tilting the hand-held controller (40) to generating control signals. A position sensor (48a) that includes a bubble (56) in a liquid is used to determine the angular position of the controller with respect to a horizontally level plane. A light source (64) emits light that is reflected by the bubble, into two opposing photodiodes (68a, 68b). A ratiometric amplifier (80) produces a signal corresponding to the ratio of the light incident on each of the photodiodes (68a, 68b) to provide a signal corresponding to the angle, relative to a horizontally level plane, by which the controller is tilted. The controller (40) can use a diffused laser light-emitting diode to transmit signals to the controlled device.

Description: POSITION SENSING CONTROLLER AND METHOD FOR GENERATING CONTROL SIGNALS CROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation-in-part of U.S. Patent Application Serial No. 08/076,032, filed June 15, 1993, which is a continuation-in-part of both U.S. Patent Application Serial No. 07/804,240, filed December 5, 1991 and issued as U.S. Patent No. 5,339,095 on August 16, 1994, and U.S. Patent Application Serial No. 07/868,835, filed April 15, 1992 and issued as U.S. Patent No. 5,218,771 on June 15, 1993. FIELD OF THE INVENTION This invention relates to an improved position sensing controller which allows a person to precisely control the movement of a remote object or device (such as a video game display character) in one or two dimensions, by simply tilting the hand-held controller. BACKGROUND OF THE INVENTION Video games are usually played with a video game controller called a "game pad," which is generally used to control operation of a game machine, i.e., a computing device dedicated to executing video games. Game controllers are also used to control personal computers and interactive television set tops. Pressing or releasing a direction key on the game controller has the effect of turning a switch on or off. For example, if the game controller is used in a racing car video game, pressing the left direction key makes the car turn to the left. The "all or nothing" action of the direction key, however, makes it difficult to control the video game. To understand the problem, it is only necessary to imagine driving a car that forces the driver to turn the steering wheel all the way in order to make even a slight turn, or to steer the car by pressing a push-button switch rather than by turning a steering wheel. U.S. Patent No. 5,059,958, issued October 22, 1991 on an application of Jacobs et al. and entitled "Manually Held Tilt Sensitive Non-Joystick Control Box" discloses the use of a control device having a box-like shaped enclosure held with both hands for tilting to produce corresponding tilt attitude control signals. A user holds the control device with both hands and presses finger-actuated "switches symmetrically disposed on the top section of the enclosure to produce auxiliary control signals." The actual circuitry within the box consists of a number of mercury switches which are either open or closed depending upon the tilt attitude of the control device. Thus, the Jacobs controller can provide a low-resolution control signal having a value selected from a limited number of discrete values. Wireless electronic controllers are used in nearly every facet of life today. Wireless controllers are used to control nearly all varieties of audio and video entertainment equipment including televisions, video cassette recorders (VCRs) , cable control boxes, stereo receivers, and compact disc players. Wireless controllers are also used to control lighting in a room, to control play of an electronic video game, and to control movement of a cursor on a computer screen. Primarily, two types of wireless communication are used between a controller and a controlled device, namely, infrared light signals and radio frequency signals. Infrared LEDs (light emitting diodes) used in such applications are typically focused and thus emit a narrow beam of infrared light. Controllers which transmit control signals through a focused infrared LED must generally be aimed at the controlled device and must generally have a clear line of sight between the controller and the controlled device for control signals transmitted by the controller to be received by the controlled device. A break in the line of sight between the controller and the controlled device, such as a person or other obstruction moving into the space between the controller and the controlled device, typically disrupts the transmission of control signals from the controller to the controlled device. Similarly, some controllers sense movement or orientation of the controller and accordingly transmit control signals. Such a controller is described, for example, in U.S. Patent Number 5,059,958 to Jacobs et al. It is generally difficult to move and orient such controllers as desired while continuously aiming the controller at a controlled device to avoid disruption in receipt of the control signal by the controlled device. In many applications, disruption in the transmission of control signals from the controller to the controlled device can have a substantial impact on the use of the controlled device. For example, disruption of a control signal from a wireless controller of a video game device can cause a player of a game to suffer the fate of a less-skilled player, including premature termination of the game. Similarly, disruption of a control signal from a locator device such as a mouse device to a computer implementing a "drag-and-drop" graphical user interface can inadvertently cause th° computer to act undesirably. Drag-and-drop graphical user interfaces are well-known and are used, for example, in Macintosh® computers available from Apple Computer, Inc. of Cupertino, California and in the Microsoft® Windows™ operating system available from Microsoft Corporation of Redmond, Washington. Focused LEDs generally focus and concentrate light energy into a conically-shaped beam, called an "aperture", and generally specify a half-angle, which is an angular measurement from the center of the aperture to the outer edge of the aperture. For example, focused LED 102 (Figure la) focuses infrared light into an aperture 106 which has a half-angle 108. When aperture 106 is aimed at a receiving photodiode 104, the intensity of the infrared light received by photodiode 104 is relatively high. However, when aperture 106 is aimed away from photodiode 104 as shown in Figure lb, the intensity of the infrared light received by photodiode 104 is relatively low and is more difficult to distinguish from background infrared light. To compensate for variations in the intensity of received light through photodiode 104, photodiode 104 is typically connected to automatic gain control ("AGC") circuitry (not shown). In controllers in which movement of the controller is likely, the intensity of the light received by a receiving photodiode such as photodiode 104 varies dramatically. When using such controller to transmit substantially continuous control information, e.g., to control a video game or to use a computer which implements a drag-and-drop graphical user interface, such AGC circuitry must quickly and accurately compensate for such intensity variations to avoid loss of control information. Most AGC circuitry currently used in controlled devices cannot compensate for such intensity variations in a received infrared control signal with sufficient quickness to avoid loss of control information. A diffused LED is not focused, i.e., has a half- angle of approximately 90° or more. Diffused LEDs can obviate the requirement of a clear line of sight between the controller and the controlled device. Similarly, since the intensity of the infrared signal does not change dramatically as a diffused LED is redirected, AGC circuitry currently used within most controlled devices can compensate for any slight variations in received infrared signals with sufficient quickness to avoid loss of control information. But to produce an infrared signal which is strong enough to be received by a controlled device at a useful distance, e.g., a distance of more than two (2) meters, a diffused LED requires more power than can be practically provided. The second type of wireless communication used between a controller and a controlled device are radio frequency (RF) signals. Controllers which transmit control signals to a controlled device by RF signals typically avoid many of the problems associated with focused infrared signals, but only with a substantial increase in cost and complexity. SUMMARY OF THE INVENTION In accordance with the present invention, an improved position sensing controller allows a person to precisely control the movement of a remote object or device (such as a video game display character) in one or two dimensions, by simply tilting the hand-held controller. In one embodiment, an improved controller senses its own angular position or orientation in two- dimensional space (relative to an X-axis and a Y-axis) . For example, when the player tilts the controller left, right, forward, or backward, the controller provides digital control signals corresponding to the new, tilted position of the controller. These digital control signals are equivalent to the control signals resulting from pressing the left, right, up, or down direction keys in a prior art game controller, so that the controller is fully compatible with existing video games. Unlike existing game controllers, however, a controller according to the present invention is simple and inexpensive, and yet provides a high-resolution control signal. In the illustrative racing car video game example described above, the "driver" is able to turn the steering wheel exactly the amount required to make a slight turn by a slight tilt of the controller, rather than having to turn the steering wheel all the way or not at all by use of a digital switch. The digital control signal can also control parameters other than the position of an object in two- dimensional space. For example, tilting the controller forward in the racing car video game example can control acceleration (the gas pedal) , while tilting the controller backward can control deceleration (the brake) . In accordance with the present invention, a controller transmits to a controlled device a control signal using a diffused laser diode. DESCRIPTION OF THE DRAWINGS Figures la and lb are block diagrams of a focused infrared LED transmitting infrared light signals to a receiving photodiode in accordance with the prior art. Figure 2a is a top view of one embodiment of a controller according to the present invention. Figure 2b is a top view of an alternative embodiment of a controller according to the present invention. Figure 2c illustrates a pair of position sensor modules which sense the angular position or orientation of the controller relative to the X-axis and the Y- axis. Figure 3 is a cross-sectional top view of a position sensor module. Figures 4a, 4b, and 4c illustrate the back, top, and side views, respectively, of a position sensor module in a miniature plastic enclosure. Figure 5 is a block diagram illustrating one embodiment of a position sensor module interfacing with a ratiometric digital instrumentation amplifier. Figures 6a through 6d illustrate a trigger pulse and three different output signals of a ratiometric digital instrumentation amplifier. Figure 7 is a block diagram of one embodiment of the circuitry of a controller in accordance with the present invention. Figures 8a through 8e illustrate five different output control signals from the circuitry of a controller in accordance with the present invention. Figure 9 is a block diagram of another embodiment of the circuitry of a controller in accordance with the present invention. Figures 10a and 10b illustrate one embodiment of the transmission protocol and a data packet used to transmit position indicating data. Figure 11 is a block diagram of one embodiment of an infrared receiver. Figure 12 is a block diagram of another embodiment of the circuitry of a controller in accordance with the present invention. Figures 13a and 13b are cross-sectional top and side views, respectively, of a two-dimensional position sensor module. Figures 13c and 13d are cross-sectional top and side views, respectively, of another embodiment of a two-dimensional position sensor module. Figure 14 is a block diagram illustrating another embodiment of a position sensor module interfacing with a ratiometric digital instrumentation amplifier. Figure 15 is a block diagram of another embodiment of the circuitry of a controller according to the present invention. Figure 16 is a block diagram of a diffused laser diode transmitting infrared light signals to a receiving photodiode in accordance with the present invention. Figure 17 illustrates the transmission of infrared light signals from a diffused laser diode to a receiving photodiode in accordance with the present invention when the direct line of sight between the diffused laser diode and the photodiode is obstructed. DETAILED DESCRIPTION Figure 2a is a top view of one embodiment of a position sensing control device 40, herein called a controller 40, according to this invention. Controller 40 is used to control a game machine, a television, an interactive television set top, or any device electrically controllable by a user. On the left side of controller 40 are four direction keys 44a-d. Direction keys 44a-d are simple on/off switches. In addition to direction keys 44a-d, controller 40 includes four (4) control keys 44e-h. Figure 2b is a top view of an alternative embodiment of a controller, namely, controller 40-6 which includes control keys 44i-k in addition to the direction and control keys of controller 40 (Figure 2a) . Figure 2c illustrates a pair of position sensor modules 48a and 48b which sense the angular position or orientation of controller 40 in two-dimensional space relative to an X-axis and a Y-axis. Each of the position sensor modules 48a and 48b senses angular position relative to a single axis. In one embodiment, the axis corresponding to position sensor module 48a is substantially orthogonal to the axis corresponding to position sensor module 48b. Position sensor modules 48a and 48b are similar to the "position detector modules" shown in Figures 7 and 10 of copending U.S. Patent Application No. 08/076,032, filed June 15, 1993, which is incorporated by reference herein. Other embodiments of position sensor modules are disclosed in copending U.S. Patent Application Serial No. 07/804,240, filed December 5, 1991 and incorporated by reference herein, and in U.S. Patent No. 5,218,771, issued June 15, 1993 and incorporated by reference herein. The output of position sensor modules 48a and 48b is translated by the microcontroller described below into the equivalent of modulated closings of direction keys 44a-d (Figure 2a) . Tnus, controller 40 may be operated either (1) by using the four direction keys 44a-d in a manual operating mode similar to a currently available game controller, or (2) by tilting controller 40 and using one of several different operating modes of the microcontroller (e.g., the "digital mode", "sliding window mode", "proportional mode", "relative mode", or "absolute mode") as described below to provide various types of control signals suited to different applications. Figure 3 is a cross-sectional top view of position sensor module 48a. Position sensor modules 48a and 48b are, in this embodiment, identical and are each a TVI501 position Detector available from TV Interactive Data Corporation of San Jose, California. Figure 3 is therefore also accurately representative of position sensor module 48b (Figure 2c) . Position sensor module 48a (Figure 3) includes a transparent cylindrical container 52 with a reflector 56 suspended in a medium 60. In one embodiment, reflector 56 is formed of air, and medium 60 is 91% isopropyl alcohol. Alternatively, medium 60 can be a light oil. Reflector 56 can be gaseous, liquid, or solid. For example, reflector 56 can be a light oil suspended in water, which is used as medium 60. Alternatively, reflector 56 can be a solid, reflective ball bearing suspended in a medium 60, such as water, oil, or air. It is appreciated that other materials can be used to form reflector 56 and medium 60 so long as (i) reflector 56 and medium 60 remain separate, (ii) a signal transmitted from a signal source (described below) passes through medium 60, (iii) reflector 56 moves freely within medium 60 and (iv) reflects the signal to a signal receiver (described below) . The operation of position sensor module 48a is largely insensitive to the size of reflector 56. Satisfactory results have been obtained when reflector 56 is as little as less than 10%, or as much as greater than 90%, of the interior volume of cylindrical container 52. When the heavier of reflector 56 or medium 60 accounts for less than about 30% of the interior volume of cylindrical container 52, a minor delay in a signal response to a movement of position sensor module 48a is observed. Such is generally the case when using a small, reflective ball bearing as reflector 56, or when using a gas bubble occupying more than 70% of the interior volume of cylindrical container 52 as reflector 56. The minor delay is a result of the greater role played by the inertia of the heavier of medium 60 and reflector 56 in the movement of reflector 56. At one end of cylindrical container 52 is an infrared light-emitting diode ("LED") 64 which transmits a signal, which is in this case infrared light and which is reflected by reflector 56. Resistor Rl (Figure 5) sets the brightness of infrared LED 64 (Figure 3) and thus the intensity of the signal. On each side of cylindrical container 52 are photodiodes 68a and 68b which receive the signal reflected by reflector 56. When position sensor module 48a is in a horizontally level position, reflector 56 is centered between photodiodes 68a and 68b. Reflector 56 is a reflective lens which, in this position, reflects equal amounts of signal, e.g., infrared light, to each of photodiodes 68a and 68b. As position sensor module 48a is rotated about the longitudinal axis (represented by dashed arrow A) of cylindrical container 52, photodiodes 68a and 68b move relative to reflector 56, which remains stationary. The movement of photodiodes 68a and 68b relative to reflector 56 gradually redirects light, increasing the incident light on one of photodiodes 68a and 68B and decreasing the incident light on the other of photodiodes 68a and 68b. Each of photodiodes 68a and 68b acts like a current source, producing a current which is proportional to the amount of incident light on the photodiode. A plug 72 seals cylindrical container 52 which holds medium 60. Figures 4a, 4b, and 4c illustrate the back, top, and side views, respectively, of position sensor module 48a which is housed in a miniature plastic enclosure 76 in order to assure repeatable alignment of the infrared LED 64 and the two photodiodes 68a and 68b. Conductive leads 78 allow electrical connections to be made to the infrared LED 64 and the photodiodes 68a and 68b. Figure 5 is a block diagram illustrating one embodiment of a cylindrical position sensor module 48a interfacing with a "ratiometric digital instrumentation amplifier" 80 (referred to herein as a "ratiometric amplifier") according to this invention. Ratiometric amplifier 80 includes a CMOS 555 timer 84 (e.g. , the TLC555 timer available from Texas Instruments, Inc. of Dallas, Texas) configured as a one-shot monostable multivibrator. In an alternative embodiment, an astable multivibrator is used. Ratiometric amplifier 80 is a high-resolution analog-to-digital converter which converts the analog output current from photodiodes 68a and 68b in position sensor module 48a to a pulse-width modulated waveform, which is called an XY output signal and which is input to the microcontroller described below. The XY output signal indicates a position of controller 40 along the X-axis or Y-axis with respect to a reference plane (e.g., a horizontal plane) . Initially, the XY output signal, which is on pin 3 of timer 84, is low. A short, active-low trigger pulse (Figure 6a) on pin 2 causes the XY output signal on pin 3 of timer 84 to go high and stay high as capacitor C2 charges through resistor R2. When the voltage across C2 reaches two-thirds of the supply voltage Vcς, capacitor C2 is discharged through pin 7 of timer 84 and the XY output signal on pin 3 of timer 84 returns to the low state. The resulting pulse-width modulated waveform, i.e., the resulting XY output signal, when controller 40 (Figure 2a) is level and reflector 56 (Figure 3) is in the center position is shown in Figure 6c. When controller 40 (Figure 2a) is tilted in one direction, causing one of position sensor modules 48a (Figure 2c) and 48b to rotate about its axis, the result is to increase the amount of incident light on one photodiode, e.g., photodiode 68a (Figure 5), and decrease the amount of incident light on the other photodiode, e.g., photodiode 68b. Position sensor module 48a is connected to timer 84 so that photodiode 68a supplies current to the control input (pin 5) of timer 84, and photodiode 68b takes away current from the control input. The control input (pin 5) of timer 84 is internally connected to a resistive voltage divider which converts the two photodiode currents of photodiodes 68a and 68b to a control voltage. The result is that the pulse width of the XY output signal on pin 3 of timer 84 is directly proportional to the ratio (rather than the difference) of the light incident on pnotodiodes 68a and 68b. When both photodiodes 68a and 68b receive equal illumination, i.e., when reflector 56 (Figure 3) is centered, photodiode 68b takes away exactly the same amount of current as photodiode 68a supplies, resulting in a zero net current at the control input (pin 5 — Figure 5) of timer 84. The resulting pulse-width modulated XY output signal on pin 3 of timer 84 is thus not affected and remains at center pulse width (Figure 6c) determined by resistor R2 (Figure 5) and capacitor C2. When photodiodes 68a and 68b receive unequal amounts of incident light, i.e., when reflector 56 (Figure 3) is not centered, a net current flows into or out of the control input (pin 5 — Figure 5) of timer 84, and changes the pulse width of the XY output signal. Figure 6d shows the resulting XY output signal on pin 3 (Figure 5) of timer 84 if photodiode 68a receives more incident light than photodiode 68b, and Figure 6b shows the resulting XY output signal if photodiode 68a (Figure 5) receives less incident light than photodiode 68b. A ratiometric amplifier, such as ratiometric amplifier 80, according to this invention provides the following advantages over a prior art analog-to-digital converter: (a) the XY output signal on pin 3 of timer 84 is proportional to the ratio (rather than the difference) of the incident light on photodiodes 68a and 68b, resulting in a circuit which is relatively independent of the power supply voltage V cc , and providing excellent noise immunity without a voltage reference, a voltage regulator, or a large filter capacitor; (b) the XY output signal is not affected by variations in the sensitivity of the analog transducers (e.g., photodiodes 68a and 68b) used to provide the input; (c) the XY output signal is not affected by variations in the absolute value of the signals that drive the analog transducers (e.g., infrared LED 64 which illuminates photodiodes 68a and 68b) ; and (d) ratiometric amplifier 80 is much less expensive than a conventional analog-to-digital converter with a differential input. Although ratiometric amplifier 80 is used in this embodiment to provide a digital output signal corresponding to the amount of incident light on photodiodes 68a and 68b, a ratiometric amplifier according to this invention can be used to provide a digital output corresponding to an analog input from a transducer sensing any measurable physical parameter such as temperature, pressure, or the like. Figure 7 is a block diagram of one embodiment of the circuitry of a controller according to the represent invention, namely, controller 40a. To simplify the drawing, direction keys 44a-d (Figure 2a) are not shown in Figure 7. Two position sensor modules 48a and 48b are connected to a single timer 84 in order to sense angular position relative to both the X-axis and the Y-axis. A microcontroller 88 configured as a transmitter provides multiplexing signals EX and EY which activate only one of position sensor modules 48a and 48b at a time to provide an input signal to timer 84. This is accomplished by selectively illuminating reflector 56 (Figure 3) in only one of position sensor modules 48a (Figure 7) and 48b at a time, e.g., when either the EX or the EY signal goes low. For example, microcontroller 88 activates the first position sensor module 48a by sending a low EX signal from pin 12 of microcontroller 88 to pin 8 of position sensor module 48a while signal EY is held high. Thus activated, position sensor module 48a senses the angular position of position sensor module 48a relative to a horizontal plane caused by rotation of position sensor module 48a about the X-axis. This angular position is referred to herein as the "X position". Microcontroller 88 then sends a trigger pulse to pin 2 of timer 84, and measures the resulting pulse width of the XY output signal on pin 3 of timer 84 which inputs to pin 4 of microcontroller 88. Next, microcontroller 88 uses a digital value representing the pulse width to generate a raw "X position value" corresponding to the X position, and digitally filters the raw X position value to eliminate hand jitter. In one embodiment, the raw X position value is filtered to produce an X position value by averaging the five (5) most recently measured X position values. After an X position value is produced, microcontroller 88 activates the second position sensor module 48b by sending a low EY signal from pin 11 of microcontroller 88 to pin 8 of position sensor module 48b while signal EX is held high, to produce a "Y position value" in a similar manner. Figures 8a-8e illustrate how the X and Y position values are converted by microcontroller 88 to pulse- width modulated output control signals on pins 7, 8, 9, and 10 of microcontroller 88 in a proportional mode, which is described below in greater detail. As described more completely below, proportional mode is used to transmit amplitude information according to a digital control protocol. Figures 8a through 8e illustrate the waveform of the output control signal on, for example, pin 9 of microcontroller 88 when controller 40a is first held in a horizontal position and is then tilted left. Figure 8a shows a high output produced when the top surface of controller 40a is horizontal. Figure 8b shows a single narrow, active-low pulse produced when controller 40a is tilted slightly to the left (e.g., a 10° tilt) . Figure 8c shows multiple narrow pulses produced when controller 40a is tilted further to the left (e.g., a 20° tilt). Figure 8d shows how the pulse width increases as the left tilt angle is increased even further (e.g., a 40° tilt). Figure 8d shows the low output produced when the left tilt angle is increased to the maximum angle (e.g., a 70° tilt). In one embodiment, the control signals are output on pins 7, 8, 9, and 10 (Figure 7) of microcontroller 88 to a controlled device (e.g., a prior art video game machine) through a 6-pin hard connector 90. Figure 9 is a block diagram of the circuitry of a controller 40b, which is a second embodiment of a controller according to the present invention and which simulates a "mouse" or other pointing device used with a personal computer ("PC") . For example, tilting controller 40b to the left moves the PC's on-screen cursor to the left. In this embodiment, controller 40b operates in the "relative mode" which is described more completely below; that is, controller 40b is a "relative" pointing device because the position of controller 40b does not map directly to a specific location on the PC screen. Instead, the angular position of controller 40b directs movement of the cursor relative to the cursor's previous position. In Figure 9, the resistances provided by the resistors R 2 and R 3 are selected to bias the control input (pin 5) of timer 84 at one-half of the supply voltage V cc . This configuration causes timer 84 to operate symmetrically on either side of "center position" (the horizontally level position of controller 40b) , and effectively increases the dynamic range of timer 84. In the embodiment of Figure 9, microcontroller 94 outputs the control signals through serial output port (pin 3) of microcontroller 94 to an infrared transmitter 100. Infrared transmitter 100 is a frequency shift key oscillator which is modulated by the control signal output on pin 3. The pulses produced by the frequency shift key oscillator are converted to infrared light by infrared LED D 2 . Switch S, is a cursor enable button which activates microcontroller 94 to select the position indicating function. Switches S 2 and S 3 , respectively, are left and right mouse buttons used to control the PC's on¬ screen cursor. Microcontroller 94 uses an infrared RS-232C serial link to communicate with the host PC (not shown), i.e., the PC to which controller 40b transmits data through infrared transmitter 100. For example, the infrared link transmits data serially at 1,200 baud, modulated with a 40 kHz carrier. An FSK (frequency shift key) format is used, where logical 1 is represented by a 40 kHz square wave, and logical 0 is represented by zero volts. Figure 10a illustrates the transmission protocol and Figure 10b illustrates a data packet typically used to transmit the position indicating data. Figure 11 is a block diagram of one embodiment of infrared receiving circuitry for use with controller 40b (Figure 9) . The infrared receiving circuitry includes an infrared receiver 110 (Figure 11) (e.g., the GP1U52X infrared receiver available from Sharp Electronics Corporation of Mahwah, New Jersey) which receives the infrared light signal transmitted by infrared transmitter 100 (Figure 9) . Power is supplied to infrared receiver 110 (Figure 11) from lines RTS and DTR of the serial port, and is regulated to five volts by voltage regulator 114 (e.g., the LP2950CZ voltage regulator available from National Semiconductor Corporation of Santa Clara, California) . Line DTR always carries a high signal (i.e., 5 to 12 volts) as controlled by the driver. Line RTS normally carries a high signal but is sometimes pulsed to momentarily carry a low signal (i.e., -5 to -12 volts) . A pulse of line RTS to momentarily carry a low signal requests an ID sequence. Diode D 3 prevents the gate of transistor 0. ! from becoming negative when line RTS goes low. Diode D 2 buffers the input to voltage regulator 114 when line RTS goes low. Transistor Q, is part of a voltage shifter which isolates the input of microcontroller 118 from the large voltage swings of the signal on line RTS. In Figure 11, infrared receiver 110 senses the infrared light signal from infrared transmitter 100 (Figure 9) , demodulates the transmitted signal, and outputs the demodulated signal to pin 5 of microcontroller 118 (Figure 11) . Microcontroller 118 outputs the signal on pin 2 to transistor Q 2 . Transistor Q 2 is a loopback switch that forces line TXD high when transistor Q 2 is turned on, by connecting line TXD to line DTR which is always high. In some applications, it is advantageous to use a "diffused laser diode" (e.g., the SFH495P diffused laser diode available from Siemens Components, Inc. of Cupertino, California) in the infrared transmitter, rather than a conventional infrared LED, to produce the infrared light beam used to transmit the control signals to the infrared receiver. Conventional infrared LEDs emit low-intensity light which is focused by a lens to produce a directional light beam. When an infrared transmitter using a conventional infrared LED is rapidly moved in a direction which causes the infrared light beam to move past the infrared receiver, the infrared receiver receives an infrared light beam which varies in intensity. The infrared receiver must compensate for this variation by using "automatic gain control" to adjust the sensitivity of the infrared receiver. When the infrared transmitter is moved too rapidly, the automatic gain control is not able to respond quickly enough, so that part of the infrared transmission is lost. By contrast, the "diffused laser diode" produces a diffused beam which is not focused by a lens and is therefore non-directional. As a result, the same amount of diffused light reaches the infrared receiver even when the infrared transmitter is rapidly moved as described above, so that the infrared receiver does not have to use the automatic gain control and no part of the infrared transmission is lost. In addition, the diffused laser diode is more efficient than a conventional infrared LED, and produces a higher intensity of infrared light which is able to travel greater distances. Figure 12 is a block diagram of the circuitry of a controller 40c, which is a third embodiment of a controller of the present invention and which uses a multiplex button scanner. The values of resistors R 2 and R 3 are selected to bias the control input (pin 5) of timer 84 at one-half of the supply voltage Vcc. This configuration causes timer 84 to operate symmetrically on either side of "center position" (the horizontally level position of controller 40c) , and effectively increases the dynamic range of timer 84. In the embodiment of Figure 12, a microcontroller 122 implements a computer process which is defined by computer instructions stored in memory (not shown) in microcontroller 122. In one embodiment, microcontroller 122 is the XC68HC05KO microcontroller available from Motorola Inc. of Phoenix, Arizona. In this same embodiment, the computer source code for microcontroller 122 is assembled using the M68HC705KICS assembler available from Motorola Inc. and installed in microcontroller 122 using conventional techniques. The computer process implemented by microcontroller 122 begins when a controlled device (e.g., a prior art video game machine — not shown) polls microcontroller 122 for X and Y position values and button status. The controlled device can be, for example, a video game machine, an interactive television set top, or a personal computer. The computer process of microcontroller 122 generates a X position value and a Y position value in the manner described above with respect to microcontroller 88 (Figure 7). Microcontroller 122, by executing the computer process, transmits the X position value and Y position value to the controlled device through an 8- pin hard connector 132 (Figure 12) according to a protocol by which the controlled device accepts control information. This protocol is called herein the "control protocol." In one embodiment, the controlled device is the Sega Genesis game machine available from Sega of Redwood City, California, and the control protocol is a control device protocol defined for the Sega Genesis game machine and description of which is also available from Sega. The determination of X and Y position values and the processing of button actuations according to the computer process of microcontroller 122 is described below in greater detail. It is appreciated that the computer process of microcontroller 122 can transmit the X and Y position values to a controlled device according to any protocol by which control information is transmitted. For example, the following are three different protocols by which X and Y position values can be transmitted to the controlled device. A game controller generally uses an established six-state protocol to communicate with a game machine. A mouse device generally uses either an established 10-state protocol or an established 16- state protocol to communicate with a personal computer. Virtual reality user-interface devices use an established VR-state protocol to communicate with a game machine. Each of these protocols is defined by the manufacturer of the particular controlled device to which controller 40c is connected. After the control protocol is finished, i.e., once microcontroller 122 has transmitted X and Y position values to the controlled device, the computer process of microcontroller 122 enters a position sensor routine and a button status routine. In the position sensor routine of the computer process implemented by microcontroller 122, X and Y position values are determined as described below. The button status routine of the computer process implemented by microcontroller 122 determines which of buttons 44a-h (Figure 2a) , if any, are pressed. Buttons 44a-h correspond to buttons S1-S8 of controller 40c (Figure 12) . According to established protocols used by currently available game machines, controller 40c is typically polled for X and Y position values and button status every 10 ms. This provides controller 40c with sufficient time to determine such information through execution of the position sensor routine and the button status routine. The position sensor routine starts by changing lines EY/DN and EX/UP from output lines, which are used to transmit information according to the control protocol, to input lines each carrying a high signal. This turns off the position sensor LED's in position sensor modules 48a and 48b and allows each of position sensor modules 48a and 48b to be tested in sequence. The signal on line PB (i.e., pin 3 of microcontroller 122) to pin 2 of timer 84 is then toggled from high to low, setting the output (pin 3) of timer 84 to high and starting the timer. The position sensor routine invokes performance of a timer routine in the computer process implemented by microcontroller 122. In the timer routine, the current time as indicated by the timer clock (not shown) of microcontroller 122 is recorded as the beginning of the time period. The timer routine monitors line XY (i.e., pin 4) of microcontroller 122 either by interrupt or by polling until the state of the signal on line XY changes from high to low. The beginning time of timer 84 is subtracted from the ending time and the difference is the digital representation of the "absolute" position of the first position sensor module 48a. In this way, position sensor module 48a is measured to produce a position value. This sequence is then repeated with the second position sensor module 48b, by setting the EX line high to turn off the LED of the first position sensor 48a and setting the EY line low to turn on the LED of the second position sensor 48b. Timer 84 is again triggered and the timer period is again measured to derive the "absolute" position of the other sensor. For a three or four sensor configuration, this sequence is repeated for each sensor. After position sensor modules 48a and 48b are measured, the computer process of microcontroller 122 (Figure 12) enters the button status routine. In the button status routine, data lines R, L, EX/UP and EY/DN are configured as input lines each carrying a low signal and button enable lines (i.e., lines BEO and BE1) are each enabled, i.e., configured as an output line carrying a high signal. First, while line BEO is enabled and line BE1 is held low, data lines R, L, EX/UP, and EY/DN data lines are read to check for the state of buttons SI through S4. Second, while line BE1 is enabled and line BEO is held low, data lines R, L, EX/UP, and EY/DN data lines are read to check for the state of buttons S5 through S8. This allows each of buttons SI through S8 to be tested to determine whether the button is in an open state or a closed state. Control signals representing the respective states of buttons S1-S8 are formatted to be sent to the game machine in conformance with the control protocol. When the position sensor and button status routines have completed, the computer process implemented by microcontroller 122 places microcontroller 122 in a default ready state and the computer process waits for the game machine to again poll microcontroller 122. As described above, a controller 40 (Figure 2a) may be operated either (l) by using the four direction keys 44a-d in a manual operating mode similar to a currently available game controller, or (2) by tilting controller 40 and using one of several different operating modes of the microcontroller (e.g., the "digital mode", "sliding window mode", "proportional mode", "relative mode", or "absolute mode") to provide various types of control signals suited to different applications. In the digital mode, the proper data lines are turned on when the sensor produces a movement beyond a preset "window" . This mode of operation is analogous to prior art game controllers in which a direction button is either pressed (i.e., "on" or closed) or released (i.e., "off" or open) . During the power-on sequence, the position of a position sensor module is sampled and an absolute position, called the "origin", is recorded in memory. A positive and negative offset, which are relative to the origin and which collectively define a window, are calculated and recorded in memory. Each time controller 40 is polled by the controlled device to which controller 40 is connected, position sensor modules 48a and 48b (Figure 2c) are checked as described above to determine a sensed position and the offsets are checked. If the sensed position is between the positive and negative offsets, i.e., within the window, the two associated lines (e.g., Right and Left) are turned off as if neither the right of left direction key is pressed. If controller 40 (Figure 2a) is tilted to the left so that the sensed position is outside (e.g., to the left of) the window formed by the positive and negative offsets, the Left sensor line is turned on during the polling by the game machine as if the left direction key is pressed (i.e., closed or "actuated") . Moving the position sensor back inside the window causes the Left sensor line to be reset to an off state as if the left direction key is released (i.e. open or "deactuated") . In the sliding window mode, as in the digital mode described above, positive and negative offsets are used for turning on and off associated data lines. However, in the sliding window mode, the positive on and off edges of the window are dynamically set. For example, if controller 40 is tilted to the left, a new or "current" origin is recorded in memory, and the window is adjusted by adding the positive and negative offsets to the current origin. In effect, the window is moved to the left, allowing the user to turn on and off the Right or Left sensor lines with only a relatively slight movement of controller 40. In the proportional mode, the sensed position is used to create an "on" period during which controller 40 simulates actuation of a direction key and an "off" period during which controller 40 simulates deactuation of the direction key. Some games implemented by a game machine allow a user to simulate an amplitude of an analog control signal using only a digital, i.e., "on/off", switch. In the car racing video game example given above, a greater amplitude can indicate a sharper turn of a steering wheel. A greater amplitude of an analog control signal is simulated by a user of existing game controllers by either actuating a switch with greater frequency or holding the switch in an actuated state for a greater time period. In proportional mode, controller 40 simulates an analog control signal including amplitude information to control a controlled device by transmitting to the controlled device control signals corresponding to a digital switch, e.g., any of direction keys 44a-d (Figure 2a) . The amplitude information is included as (i) a frequency of transitions from a deactuated state to an actuated state of the switch, (ii) a percentage of the time the switch is in an actuated state (i.e., the "duty cycle" of the switch) , (iii) a length of time the switch is held in an actuated state, or (iv) a combination of any of (i) through (iii) . The amplitude information represented by the simulated analog control signal is proportional to the difference between the sensed position and the origin. In other words, the further controller 40 is tilted, a signal representing a more frequently actuated switch or a switch which is held in an actuated state for a longer period of time is emulated. Different representations of amplitude information can be used to more accurately communicate the amplitude information to a particular game. For example, one game may determine amplitude of a control signal by counting the number of actuations of a switch within a given period of time and another game may determine amplitude of a control signal by measuring the length of time a switch is held in an actuated state. To cause controller 40 to properly represent amplitude information to a particular game executing within a controlled device, the controlled device can preload a response table into a microcontroller of controller 40, e.g., microcontroller 122 (Figure 12). The response table specifies, for each of a number of amplitudes, a pattern of "on" and "off" signals which correspond to a digital switch and by which a specific amplitude is represented. Each time controller 40 is polled, a sensed position of a position sensor module, such as position sensor modules 48a and 48b, is determined and a pattern corresponding to an amplitude equal to the difference between the sensed position and the origin is retrieved. The retrieved pattern is then used to transmit control signals representing actuations and deactuations of a control switch to transmit the amplitude information to the controlled device. In the relative mode, each time a position sensor is polled, the difference between the current sensed position and a previous sensed position is measured and transmitted according to the control protocol. The previous sensed position is subtracted from the current sensed position to derive a relative movement measurement. This relative movement measurement is typically used to simulate control by a mouse device and is therefore typically transmitted to a controlled personal computer according to an established mouse control protocol. In the absolute mode, the sensed position of the position sensor is assembled into a packet and transmitted to the controlled device according to the control protocol. The controlled device uses the sensed position to control the position of, for example, a cursor on a screen. In the absolute mode, the position of the cursor on the screen corresponds directly to the sensed position of the position sensor. Absolute mode is well-suited to virtual reality applications in which the control protocol is a virtual reality control protocol, e.g., the VR-state control protocol described above. Figures 13a and 13b are cross-sectional top and side views, respectively, of a two-dimensional position sensor module 150a. In one embodiment, two-dimensional position sensor module 150a includes a transparent spherical container 154a with a reflector 158, e.g., a bubble of air, suspended in a medium 162, e.g., isopropyl alcohol. It is appreciated that other reflectors and media are suitable for use in two- dimensional position sensor 150a as discussed above with respect to reflector 56 (Figure 3) and medium 60 of position sensor module 48a. An infrared light- emitting diode ("LED") 166 (Figure 13a) located underneath container 154a illuminates reflector 158, which reflects the infrared light to four photodiodes 170a-d positioned as shown in Figures 13a and 13b. When two-dimensional position sensor module 150a is in a horizontally level position (as in Figures 13a and 13b) , reflector 158 is centered between photodiodes 170a-d and reflects equal amounts of light to each of photodiodes I70a-d. As two-dimensional position sensor module 150a is rotated, for example, about the X-axis (Figure 13a) , reflector 158 remains stationary and gradually redirects light between the first opposing pair of photodiodes 170a and 170b, increasing the incident light on one photodiode (e.g. , photodiode 170a) and decreasing the incident light on the other photodiode (e.g., photodiode 170b) . Tilting two- dimensional position sensor module 150a about the Y- axis similarly redirects light between the second opposing pair of photodiodes 170c and 170d. In other respects, the operation of two- dimensional position sensor module 150a is similar to the operation of cylindrical position sensor modules 48a and 48b (Figure 2c) . However, a single two- dimensional position sensor such as two-dimensional position sensor module 150a (Figures 13a and 13b) is capable of sensing the angular position or orientation of controller 40 in two-dimensional space relative to both the X-axis and the Y-axis. By comparison, two cylindrical position sensor modules 48a and 48b (Figure 2c) are required to sense angular position relative to both the X-axis and the Y-axis. For most applications, it is less expensive to use a single two-dimensional position sensor such as two-dimensional position sensor module 150a (Figures 13a and 13b) than a pair of cylindrical position sensors such as position sensor modules 48a and 48b (Figure 2c) . Figures 13c and 13d are cross-sectional top and side views, respectively, of another embodiment of a two-dimensional position sensor, namely, two- dimensional position sensor module 150b. Two- dimensional position sensor module 150b uses a hemispherical container 154b instead of a spherical container. For some applications, a hemispherical container may have the advantage of being more compact or more easily manufactured. The operation of two- dimensional position sensor module 150b is analogous to the operation of two-dimensional position sensor module 150a (Figures 13a and 13b) as described above. Figure 14 is a block diagram illustrating one embodiment of a two-dimensional position sensor module 150 (e.g., either two-dimensional position sensor module 150a of Figures 13a and 13b or two-dimensional position sensor module 150b of Figures 13c and 13d) interfacing with a ratiometric digital instrumentation amplifier 174 (referred to herein as a "ratiometric amplifier") according to this invention. Ratiometric amplifier 174 is a CMOS 555 timer 84 (e.g., the TLC555 timer available from Texas Instruments, Inc. of Dallas, Texas) configured as a one-shot monostable multivibrator, and the operation of ratiometric amplifier 174 includes analogous to the operation of ratiometric amplifier 80 (Figure 5) described above. In an alternative embodiment, timer 84 (Figure 14) is configured as an astable multivibrator as described above with respect to ratiometric amplifier 80 (Figure 5) . Figure 15 is a block diagram of the circuitry of a controller 40d, which is a fourth embodiment of a controller in accordance with the present invention. Two-dimensional position sensor module 150, which can be two-dimensional position sensor module 150a (Figures 13a and 13b) or two-dimensional position sensor module 150b (Figure 13c and 13d) , is connected to timer 84 in order to sense angular position relative to both the X- axis and the Y-axis. A microcontroller 180 configured as a transmitter provides multiplexing signals EXC, EXA and EYC, EYA which activate only one opposing pair of the photodiodes 170a-d at a time. For example, microcontroller 180 activates the first opposing pair of photodiodes 170a and 170b in order to sense the X position. Microcontroller 180 activates photodiodes 170a and 170b by applying a high-level voltage (logic 1) to signal EXC and a low-level voltage (logic 0) to signal EXA. During sensing of the X position, signals EYC and EYA are held in a high-impedance input state. Microcontroller 180 then (i) triggers timer 84 to produce an XY output signal on pin 3 of timer 84, (ii) generates a corresponding digitally filtered X position value, and (iii) converts the X position value to a pulse-width modulated output signal. The operation of microcontroller 180 is analogous to that of microcontroller 88 (Figure 7) described above. Next, microcontroller 180 (Figure 15) activates multiplexed signals EYC and EYA in a manner analogous to the activation of signals EXC and EXA above to activate the second opposing pair of photodiodes 170c and 170d to thereby sense the Y position. During sensing of the Y position, signals EXC and EXA are held in a high-impedance input state. The control signals are output on pin 3 of microcontroller 180 to a conventional infrared transmitter 190 which transmits the control signals to a conventional infrared receiver, such as infrared receiver 110 (Figure 11) . The operation of infrared transmitter 190 is analogous to the operation of infrared transmitter 100 (Figure 9) as described above. The demodulated control signals are then used to drive four direction key inputs on a prior art video game machine (not shown) . As described above, it is advantageous to use a "diffused laser diode" (e.g., the SFH495P diffused laser diode available from Siemens Components, Inc. of Cupertino, California) , rather than a conventional infrared LED, to produce the infrared light beam used to transmit the control signals to the infrared receiver. Computer programs for microcontroller 122 can be assembled, in one embodiment, using the M68HC705KICS assembler available from Motorola Inc. of Phoenix, Arizona. When assembled and installed in microcontroller 122 (Figure 12) , various computer programs can form computer processes which operate controller 40c according to the above-described digital mode, relative mode, and absolute mode, respectively. The particular computer language and the particular microcontroller used are not an essential aspect of this invention. In view of this disclosure, those skilled in the art can implement the invention using a different computer language and/or a different microcontroller. According to the present invention, a controller (not shown) uses a diffused laser diode 202 (Figure 16) to transmit control signals to a controlled device 204. Controlled device 204 includes an infrared receiver 206 for receiving the control signals. Diffused laser diode 202 is shown in two alternate positions 202A and 202B, which correspond to two alternate positions of a controller and in which diffused laser diode 202 is not aimed in the direction of receiver 206. Since diffused laser diode 202 does not produce a focused beam of infrared light, the signal received by receiver 206 is substantially as strong as if diffused laser diode 202 were aimed directly at receiver 206. Accordingly, the intensity of the infrared signal recaived by receiver 206 is substantially constant irrespective of the direction in which diffused laser diode 202 is aimed. As a result, any AGC circuitry (not shown) in controlled device 204 is needed only to make minor adjustments to compensate for variations in the intensity of the received signal and, in some instances, can be omitted altogether. Since only minor adjustments in the intensity of the received signals are needed, AGC circuitry in controlled device 204 can typically make such adjustments with sufficient quickness to avoid loss of control information in the received signals. A diffused laser diode such as diffused laser diode 202 produces an infrared light of substantially greater intensity than infrared light produced by non¬ laser LEDs. As a result, che infrared signal transmitted by diffused laser diode 202 is received by controlled device 206 despite the diffused, unfocused nature of the infrared light emitted by diffused laser diode 202. Diffused laser diode 202 effectively transmits control signals to controlled device 206 from distances from which conventional controllers transmit control signals to controlled device 206. Figure 17 shows a second use of a diffused laser diode 304 in a controller 302. Diffused laser diode 304 is used by controller 302 to transmit an infrared signal to controlled device 306, which receives the infrared signal through receiver 308. As shown in Figure 17, an obstruction 310 is positioned between diffused laser diode 304 and receiver 308 such that infrared light emitted by diffused laser diode 304 cannot directly pass to receiver 308. However, since infrared light emitted by diffused laser diode 304 is not focused, infrared light is transmitted in the direction of arrow Al at about the same intensity as infrared light transmitted directly toward receiver 308. The light transmitted in the direction of arrow Al is reflected by an object, e.g., a ceiling (not shown) , and is received by receiver 308 as represented by arrow A2. In one embodiment, diffused laser diode 304 and diffused laser diode 202 (Figure 16) are the SFH495P diffused laser diode available from Siemens Components, Inc. of Cupertino, California. Diffused laser diodes 202 and 304 can generally be directly substituted for conventional infrared LEDs used in conventional controllers without requiring any changes to the circuitry therein. The circuitry (not shown) which encodes and transmits control signals as infrared signals through diffused laser diodes 202 and 304 is conventional and generally known. Similarly, the circuitry (not shown) by which control signals are received as and decoded from infrared signals in receivers 206 and 308 is also conventional and generally known. The above description is illustrative only and is not limiting. The present invention is limited only by the claims which follow. It is to be understood that the above description is intended to be illustrative and not restrictive. Many variations of the invention will become apparent to those of skill in the art upon review of this disclosure. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents. COMPONENT RATINGS IN ONE EMBODIMENT FIG. 5 Rl 680 FIG. 5 R2 47K FIG. 5 C2 0.1 FIG. 5 U3 TLC555 FIG. 7 Cl 0.1 RC0805 FIG. 7 C2 0.1 RC0805 FIG. 7 Jl 6PCON FIG. 7 Rl 680 RC0805 FIG. 7 R2 47K RC0805 FIG. 7 U3 TLC3555 FIG. 7 Ul TV1501 FIG. 7 U2 TV1501 FIG. 7 U4 TV1609 FIG. 7 Yl KBR3.58MKS RESON3 FIG. 9 BT1 3V FIG. 9 Cl 0.1 RC0805 FIG. 9 C2 0.1 RC0805 FIG. 9 C3 22 SIZEC FIG. 9 D2 NEC-SE1003 DIODEO.l FIG. 9 Ql MMBT3904 SOT23 3 FIG. 9 Q2 MMBT4401 SOT235 FIG. 9 Rl 680 FIG. 9 R2 73K RC0805 FIG. 9 R3 270K RC0805 FIG. 9 R4 0.8 RC0805 FIG. 9 Ul TVI501 FIG. 9 U2 TVI501 FIG. 9 U3 TLC555 FIG. 9 U4 TVI603S FIG. 9 Yl KBR3.58MKS RESON3 FIG. 11 Cl 2.2 FIG. 11 Dl LDH1113 FIG. 11 D2 1N914 FIG. 11 D3 1N914 FIG. 11 Jl 6PCON FIG. 11 Ql VN0300L FIG. 11 Q2 VN0300L FIG. 11 Rl 24K FIG. 11 R2 2K FIG. 11 Ul GP1U52X FIG. 11 U2 TV1701 SOL-16 FIG. 11 U3 TO-92 LP2950CZ-5 FIG. 11 Yl KBR3.58MKS RES0N3 FIG. 12a Cl 0.1 RC0805 FIG. 12a C2 0.1 RC0805 FIG. 12a Dl 1N914 FIG. 12a D2 1N914 FIG. 12a Rl 680 RC0805 FIG. 12a R2 120K RC0805 FIG. 12a R3 270K RC0805 FIG. 12a R4 680 FIG. 12a Ul TVI501 FIG. 12a U2 TVI501 FIG. 12a U3 TLC555 FIG. 12a Yl KBR3.58MKS RES0N3 FIG. 12b C3 22 UF SIZE C FIG. 12b D3 1N914 FIG. 12b Jl 9PC0N FIG. 12b U4 TVI609 FIG. 14 C2 0.1 FIG. 14 Rl 680 FIG. 14 R2 47K FIG. 14 U3 TLC555 FIG. 15 C2 0.1 FIG. 15 Rl 680 FIG. 15 R2 47K FIG. 15 Ul TVI610 FIG. 15 U2 TLC555 FIG. 15 Yl KBR3.58MKS

Claims: CLAIMS What is claimed is: 1. A position sensor module comprising: a signal source for emitting a signal; first and second signal sensors; and a reflector movably positioned relative to first and second signal sensors; wherein the first and second signal sensors are positioned to receive the signal reflected from the reflector; further wherein the first signal sensor and the second signal sensor are coupled to provide a sensor output signal indicative of the position of the reflector relative to the first and second signal sensors. 2. The position sensor module of Claim 1 wherein the first and second signal sensors define a reference axis; and further wherein the sensor output signal is related to an angle between the reference axis and a reference plane. 3. The position sensor module of Claim 1 wherein the reflector is movably positioned within a container. 4. The position sensor module of Claim 3 wherein the container is cylindrical. 5. The position sensor module of Claim 3 wherein the container defines a longitudinal axis; and further wherein rotation of the container about the longitudinal axis causes relative movement between the reflector and the first and second signal sensors. 6. The position sensor of Claim 1 wherein the reflector is spherical in shape. 7. The position sensor of Claim 1 wherein the reflector comprises a bubble in a liquid. 8. The position sensor of Claim 7 wherein the bubble is a gas bubble. 9. The position sensor of Claim 7 wherein the bubble is a second liquid, which is different from the first-mentioned liquid; further wherein the first liquid has a first density and the second liquid has a second density, which is different than the first density; and further wherein the first and second liquids remain substantially separate within the container. 10. The position sensor module of Claim 1 wherein the sensor output signal is proportional to the ratio of the strength of signal received by the first signal sensor and the strength of signal received by the second signal sensor. 11. A controller comprising: a position sensor module according to Claim 1; and a signal conditioner, operatively coupled to the first position sensor module, for converting the sensor output signal to a control signal. 12. The controller of Claim 11 wherein the signal conditioner converts the sensor output signal to a conditioned output signal. 13. The controller of Claim 12 wherein the conditioned output signal has a pulse width which is proportional to the strength of signal received by the first signal sensor and the strength of signal received by the second signal sensor. 14. The controller of Claim 13 wherein the signal conditioner further comprises: a microcontroller for converting the conditioned output signal into the control signal. 15. The controller of Claim 14 further comprising: an infrared transmitter for transmitting the control signals to a receiver. 16. The controller of Claim 15 wherein the infrared transmitter further comprises: a diffused laser diode. 17. The controller of Claim 14 further comprising: a radio frequency transmitter for transmitting the control signals to a receiver. 18. The controller of Claim 14 further comprising: an ultrasonic transmitter for transmitting the control signals to a receiver. 19. The controller of Claim 14 wherein the microcontroller uses a digital mode interface to communicate with a controlled device. 20. The controller of Claim 14 wherein the microcontroller uses a sliding window mode interface to communicate with a controlled device. 21. The controller of Claim 14 wherein the microcontroller uses a proportional mode interface to communicate with a controlled device. 22. The controller of Claim 14 wherein the microcontroller uses a relative mode interface to communicate with a controlled device. 23. The controller of Claim 14 wherein the microcontroller uses an absolute mode interface to communicate with a controlled device. 24. The controller of Claim 11 further comprising: an infrared transmitter for transmitting the control signals to a receiver. 25. The controller of Claim 24 wherein the infrared transmitter further comprises: a diffused laser diode. 26. The controller of Claim 11 further comprising: a radio frequency transmitter for transmitting the control signals to a receiver. 27. The controller of Claim 11 further comprising: an ultrasonic transmitter for transmitting the control signals to a receiver. 28. The controller of Claim 11 wherein the signal conditioner uses a digital mode interface to communicate with a controlled device. 29. The controller of Claim 11 wherein the signal conditioner uses a sliding window mode interface to communicate with a controlled device. 30. The controller of Claim 11 wherein the signal conditioner uses a proportional mode interface to communicate with a controlled device. 31. The controller of Claim 11 wherein the signal conditioner uses a relative mode interface to communicate with a controlled device. 32. The controller of Claim 11 wherein the signal conditioner uses an absolute mode interface to communicate with a controlled device. 33. The controller of Claim 11 further comprising: a second position sensor module, which is different from the first-mentioned position sensor module and which is operatively coupled to the signal conditioner, the second position sensor module comprising: a second signal source, which is different from the first-mentioned signal source, for emitting a second signal, different from the first-mentioned signal; third and fourth signal sensors; and a second reflector, which is different from the first-mentioned reflector and which is movably positioned relative to third and fourth signal sensors; wherein the third and fourth signal sensors are positioned to receive the second signal reflected from the second reflector; further wherein the third signal sensor and the fourth signal sensor are coupled to provide a second sensor output signal, which is different from the first-mentioned sensor output signal and which is indicative of the position of the second reflector relative to the third and fourth signal sensors; wherein the signal conditioner converts the second sensor output signal into a second control signal, which is different from the first- mentioned control signal. 34. The controller of Claim 33 wherein the first and second signal sensors define a first reference axis and the third and fourth signal sensors define a second reference axis; further wherein the first sensor output signal is related to an angle between the first reference axis and a reference plane; and further wherein the second sensor output signal is related to an angle between the second reference axis and the reference plane. 35. The controller of Claim 34 wherein the first reference axis is substantially orthogonal to the second reference axis. 36. The controller of Claim 33 wherein the first reflector is movably positioned within a first container; and further wherein the second reflector is movably positioned within a second container. 37. The controller of Claim 36 wherein the first and second containers are cylindrical. 38. The controller of Claim 36 wherein the first container defines a first longitudinal axis and the second container defines a second longitudinal axis; further wherein rotation of the first container about the first longitudinal axis causes relative movement between the first reflector and the first and second signal sensors; and further wherein rotation of the second container about the second longitudinal axis causes relative movement between the second reflector and the third and fourth signal sensors. 39. The controller of Claim 33 wherein the first sensor output signal is proportional to the ratio of the strength of the first signal received by the first signal sensor and the strength of the first signal received by the second signal sensor; and further wherein the second sensor output signal is proportional to the ratio of the strength of the second signal received by the third signal sensor and the strength of the second signal received by the fourth signal sensor. 40. The controller of Claim 39 wherein the signal condition converts the first and second sensor output signals to first and second conditioned output signals, respectively. 41. The controller of Claim 40 wherein the first conditioned output signal has a pulse width which is proportional to the ratio of the strength of the first signal received by the first signal sensor and the strength of the first signal received by the second signal sensor; and further wherein the second conditioned output signal has a pulse width which is proportional to the ratio of the strength of the second signal received by the third signal sensor and the strength of the second signal received by the fourth signal sensor. 42. The controller of Claim 39 wherein the signal conditioner further comprises: a microcontroller for converting the first and second conditioned output signals into the first and second control signals. 43. The controller of Claim 33 wherein the signal conditioner alternately activates the first and second position sensor modules by alternately activating the first and second signal sources, respectively. 44. A position sensor module comprising: a signal source for emitting a signal; first, second, third, and fourth signal sensors; and a reflector movably positioned relative to the first, second, third, and fourth signal sensors; wherein the first, second, third, and fourth signal sensors are positioned to receive the signal reflected from the reflector; further wherein the first signal sensor and the second signal sensor are coupled to provide a first sensor output signal indicative of the position of the reflector relative to the first and second signal sensors; and further wherein the third signal sensor and fourth signal sensor are coupled to provide a second sensor output signal indicative of the position of the reflector relative to the third and fourth signal sensors. 45. The position sensor module of Claim 44 wherein the first sensor output signal is proportional to the ratio of the strength of the signal received by the first signal sensor and the strength of the signal received by the second signal sensor; and further wherein the second sensor output signal is proportional to the ratio of the strength of the signal received by the third signal sensor and the strength of the signal received by the fourth signal sensor. 46. The position sensor module of Claim 44 wherein the first and second signal sensors define a first reference axis and the third and fourth signal sensors define a second reference axis; and further wherein the rotation of the position sensor module about the first or second axis causes movement of the reflector relative to the first and second signal sensors or relative to the third and fourth signal sensors, respectively. 47. The position sensor module of Claim 44 wherein the reflector is spherical in shape. 48. The position sensor module of Claim 44 wherein the reflector is non-spherical in shape. 49. The position sensor module of Claim 44 wherein the reflector comprises a bubble in a liquid. 50. The position sensor module of Claim 49 wherein the reflector comprises a gas bubble. 51. The position sensor of Claim 49 wherein the bubble is a second liquid, which is different from the first-mentioned liquid; further wherein the first liquid has a first density and the second liquid has a second density, which is different than the first density; and further wherein the first and second liquids remain substantially separate. 52. The position sensor module of Claim 44 wherein the first and second signal sensors define a first reference axis and the third and fourth signal sensors define a second reference axis; further wherein the first sensor output signal is related to an angle between the first reference axis and a reference plane; and further wherein the second sensor output signal is related to an angle between the second reference axis and the reference plane. 53. The position sensor module of Claim 52 wherein the first reference axis is substantially orthogonal to the second reference axis. 54. The position sensor module of Claim 44 wherein the reflector is movably positioned within a container. 55. The position sensor module of Claim 54 wherein at least a part of an inner surface of the container is spherical. 56. The position sensor module of Claim 52 wherein the reflector is movably positioned within the container; further wherein rotation of the container about a first longitudinal axis, which is substantially orthogonal to the first reference axis, causes relative movement between the reflector and the first and second signal sensors; and further wherein rotation of the container about a second longitudinal axis, which is substantially orthogonal to the second reference axis, causes relative movement between the second reflector and the third and fourth signal sensors. 57. A controller comprising: a position sensor module as in Claim 44; and a signal conditioner, operatively coupled to the position sensor module, for converting the first and second sensor output signals into control signals. 58. The controller of Claim 57 wherein the signal conditioner converts the first sensor output signal into a first conditioned output signal having a pulse width proportional to the ratio of the strength of the signal received by the first signal sensor and the strength of the signal received by the second signal sensor; and further wherein the signal conditioner converts the second sensor output signal into a second conditioned output signal having a pulse width proportional to the ratio of the strength of the signal received by the third signal sensor and the strength of the signal received by the fourth signal sensor. 59. The controller of Claim 58 wherein the signal conditioner comprises: a microcontroller for converting the first and second conditioned output signals into control signals. 60. The controller of Claim 59 wherein the microcontroller uses a digital mode interface to communicate with a controlled device. 61. The controller of Claim 59 wherein the microcontroller uses a sliding window mode interface to communicate with a controlled device. 62. The controller of Claim 59 wherein the microcontroller uses a proportional mode interface to communicate with a controlled device. 63. The controller of Claim 59 wherein the microcontroller uses a relative mode interface to communicate with a controlled device. 64. The controller of Claim 59 wherein the microcontroller uses an absolute mode interface to communicate with a controlled device. 65. The controller of Claim 57 wherein the signal conditioner controls the position sensor module to multiplex the first and second sensor output signals by alternately activating (i) the first and second signal sensors and (ii) the third and fourth signal sensors. 66. The controller of Claim 57 further comprising an infrared transmitter for transmitting the control signals to a receiver. 67. The controller of Claim 66 wherein the infrared transmitter further comprises a diffused laser diode . 68. The controller of Claim 57 further comprising a radio frequency transmitter for transmitting the control signals to a receiver. 69. The controller of Claim 57 further comprising an ultrasonic transmitter for transmitting the control signals to a receiver. 70. The controller of Claim 57 wherein the signal conditioner uses a digital mode interface to communicate with a controlled device. 71. The controller of Claim 57 wherein the signal conditioner uses a sliding window mode interface to communicate with a controlled device. 72. The controller of Claim 57 wherein the signal conditioner uses a proportional mode interface to communicate with a controlled device. 73. The controller of Claim 57 wherein the signal conditioner uses a relative mode interface to communicate with a controlled device. 74. The controller of Claim 57 wherein the signal conditioner uses an absolute mode interface to communicate with a controlled device. 75. A method comprising the steps of: emitting a signal from a signal source; reflecting the signal from a reflector movably positioned relative to first and second signal sensors; receiving the signal with the first and second signal sensors; coupling the first and second signal sensors to provide a sensor output signal indicative of the position of the reflector relative to the first and second signal sensors. 76. The method of Claim 75 further comprising: converting the sensor output signal into a control signal. 77. The method of Claim 75 wherein the first sensor output signal is directly related to an angle between a first reference axis, which is defined by the first and second signal sensors, and a reference plane. 78. The method of Claim 75 wherein the sensor output signal is proportional to the ratio of the strength of the signal received by the first signal sensor and the strength of the signal received by the second signal sensor. 79. The method of Claim 78 further comprising: generating a conditioned signal whose pulse width is proportional to the ratio of the strength of the signal received by the first signal sensor and the strength of the signal received by the second signal sensor. 80. The method of Claim 75 further comprising the steps of: emitting a second signal, which is different from the first-mentioned signal, from a second signal source, which is different from the first- mentioned signal source; reflecting the signal from a second reflector, which is different from the first- mentioned reflector and which is movably positioned relative to third and fourth signal sensors; receiving the second signal with the third and fourth signal sensors; and coupling the third and fourth signal sensors to provide a second sensor output signal, which is different from the first-mentioned sensor output signal and which is indicative of the position of the second reflector relative to the third and fourth signal sensors. 81. The method of Claim 80 further comprising: converting the second sensor output signal into an additional control signal. 82. The method of Claim 80 wherein the first sensor output signal is related to an angle between a first reference axis, which is defined by the first and second signal sensors, and a reference plane; and further wherein the second sensor output signal is related to an angle between a second reference axis, which is defined by the third and fourth signal sensors, and the reference plane. 83. The method of Claim 80 wherein the first sensor output signal is proportional to the ratio of the strength of the first signal received by the first signal sensor and the strength of the first signal received by the second signal sensor; further wherein the second sensor output signal is proportional to the ratio of the strength of the second signal received by the third signal sensor and the strength of the second signal received by the fourth signal sensor. 84. The method of Claim 83 further comprising: generating a first conditioned signal whose pulse width is proportional to the ratio of the strength of the first signal received by the first signal sensor and the strength of the first signal received by the second signal sensor; and generating a second conditioned signal whose pulse width is proportional to the ratio of the strength of the second signal received by the third signal sensor and the strength of the second signal received by the fourth signal sensor. 85. A method comprising the steps of: emitting a signal from a signal source; reflecting the signal from a reflector movably positioned relative to first, second, third, and fourth signal sensors; receiving the signal with the first, second, third, and fourth signal sensors; coupling the first and second signal sensors to provide a first sensor output signal indicative of the position of the reflector relative to the first and second signal sensors; and coupling the third and fourth signal sensors to provide a second sensor output signal indicative of the position of the reflector relative to the third and fourth signal sensors. 86. The method of Claim 85 further comprising: converting the first and second sensor output signals into control signals. 87. The method of Claim 85 wherein the first sensor output signal is related to an angle between a first reference axis, which is defined by the first and second signal sensors, and a reference plane; and further wherein the second sensor output signal is related to an angle between a second reference axis, which is defined by the third and fourth signal sensors, and the reference plane. 88. The method of Claim 85 wherein the first sensor output signal is proportional to the ratio of the strength of the signal received by the first signal sensor and the strength of the signal received by the second signal sensor; and further wherein the second sensor output signal is proportional to the ratio of the strength of the signal received by the third signal sensor and the strength of the signal received by the fourth signal sensor. 89. The method of Claim 88 further comprising: generating a first conditioned signal whose pulse width is proportional to the ratio of the strength of the signal received by the first signal sensor and the strength of the signal received by the second signal sensor; and generating a second conditioned signal whose pulse width is proportional to the ratio of the strength of the signal received by the third signal sensor and the strength of the signal received by the fourth signal sensor. 90. A controller comprising: position indicating circuitry which produces a position signal representative of a position of the controller; and a wireless transmitter connected to the position sensing circuitry so as to transmit the position signal to a wireless receiver operatively to a controlled device, the wireless transmitter comprising a diffused laser diode. 91. A position sensing circuit comprising: a first sensor which receives a first signal; a second sensor which receives a second signal; and a ratiometric amplifier for generating a ratiometric output signal which is proportional to the ratio of the strength of the first signal received by the first sensor and the strength of the second signal received by the second sensor. 92. The position sensing circuit of Claim 91 wherein the ratiometric output signal is a digital signal whose pulse width is proportional to the ratio of the strength of the first signal received by the first sensor and the strength of the second signal received by the second sensor. 93. A controller for transmitting to a controlled device control signals encoded in a light signal, the controller comprising a diffused laser diode. 94. The controller of Claim 93 wherein the light signal is an infrared signal. 95. A method of transmitting a control signal to a controlled device, the method comprising: using a diffused laser diode to transmit a light signal. 96. The method of Claim 95 wherein the light signal is an infrared signal. 97. The method of Claim 95 further comprising: receiving within the controlled device a light signal

Inventors: REDFORD PETER M, STERN DONALD S, REDFORD, PETER, M., STERN, DONALD, S.
Applicants: TV INTERACTIVE DATA CORP, TV INTERACTIVE DATA CORPORATION
Application year: 1995
Main classification: G09G5
IPC codes: A63F13, G01C9, G06F3